Bump version: v2.0.0b1

ci: fix circle ci image (#750 )
* ci: fix circle min image * Apply suggestions from code review Co-authored-by: Joe Rickerby <joerick@mac.com> Co-authored-by: Joe Rickerby <joerick@mac.com>
2021-07-09 18:56:12 +01:00 · 2021-07-09 13:30:06 -04:00 · 2021-07-09 12:23:06 -04:00 · 2021-07-09 09:16:20 -04:00 · 2021-07-08 09:03:35 +01:00 · 2021-07-06 00:48:50 +02:00
116 changed files with 4901 additions and 25638 deletions
@@ -3,7 +3,7 @@ version: 2
 jobs:
  osx-python3.6:
    macos:
-      xcode: 9.4.1
+      xcode: 12.5.1
    environment:
      PYTHON: python3
    steps:
@@ -1,7 +0,0 @@
-# config file for https://github.com/bobvanderlinden/probot-auto-merge
-
-# no approvals required, just the label is enough
-minApprovals: {}
-
-requiredLabels:
- merge when green
@@ -0,0 +1,10 @@
+version: 2
+updates:
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    ignore:
+      - dependency-name: "actions/*"
+        update-types: ["version-update:semver-minor", "version-update:semver-patch"]
@@ -3,7 +3,7 @@ name: Test
 on:
  push:
    branches:
-      - master
+      - main
  pull_request:
    paths-ignore:
      - 'docs/**'
@@ -17,7 +17,7 @@ jobs:
    steps:
    - uses: actions/checkout@v2
    - uses: actions/setup-python@v2
-    - uses: pre-commit/action@v2.0.0
+    - uses: pre-commit/action@v2.0.3

  test:
    name: Test cibuildwheel on ${{ matrix.os }}
@@ -37,14 +37,10 @@ jobs:

    - name: Install dependencies
      run: |
-        python -m pip install -e ".[dev]"
-
-    - name: Get PR labels
-      id: pr-labels
-      uses: joerick/pr-labels-action@v1.0.6
+        python -m pip install ".[test]"

    - name: Sample build
-      if: contains(steps.pr-labels.outputs.labels, ' ci-sample-build ')
+      if: "contains(github.event.pull_request.labels.*.name, 'CI: Sample build')"
      run: |
        python bin/sample_build.py

@@ -74,7 +70,7 @@ jobs:
    - uses: actions/setup-python@v2
    - name: Install dependencies
      run: |
-        python -m pip install -r requirements-dev.txt
+        python -m pip install ".[test]"

    - name: Set up QEMU
      id: qemu
@@ -11,19 +11,25 @@ jobs:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
-    - uses: actions/setup-python@v2
-      name: Install Python 3.9
-      with:
-        python-version: 3.9
-        architecture: x64
-    - name: Install dependencies
-      run: python -m pip install ".[dev]"
+    - uses: excitedleigh/setup-nox@v2.0.0
+
    - name: "Run update: dependencies"
-      run: python ./bin/update_dependencies.py
+      run: nox --force-color -s update_constraints
    - name: "Run update: python configs"
-      run: python ./bin/update_pythons.py --force
+      run: nox --force-color -s update_pins
+    - name: "Run update: docs user projects"
+      run: nox --force-color -s update_proj
+
+    # we use this step to grab a Github App auth token, so that PRs generated by this workflow
+    # run the GHA tests.
+    - uses: tibdex/github-app-token@v1
+      id: generate-token
+      with:
+        app_id: ${{ secrets.CIBUILDWHEEL_BOT_APP_ID }}
+        private_key: ${{ secrets.CIBUILDWHEEL_BOT_APP_PRIVATE_KEY }}
+
    - name: Create Pull Request
-      if: github.ref == 'refs/heads/master' && github.repository == 'joerick/cibuildwheel'
+      if: github.ref == 'refs/heads/main' && github.repository == 'pypa/cibuildwheel'
      uses: peter-evans/create-pull-request@v3
      with:
        commit-message: Update dependencies
@@ -33,4 +39,5 @@ jobs:

          PR generated by "Update dependencies" [workflow](https://github.com/${{github.repository}}/actions/runs/${{github.run_id}}).
        branch: update-dependencies-pr
+        token: ${{ steps.generate-token.outputs.token }}
        delete-branch: true
@@ -114,3 +114,6 @@ site/

 # Virtual environments
 venv*
+
+# PyCharm
+.idea/
@@ -1,7 +1,7 @@
 repos:

 - repo: https://github.com/pre-commit/pre-commit-hooks
-  rev: v3.4.0
+  rev: v4.0.1
  hooks:
  - id: check-case-conflict
  - id: check-merge-conflict
@@ -13,38 +13,8 @@ repos:
  - id: mixed-line-ending
  - id: trailing-whitespace

- repo: https://github.com/PyCQA/isort
-  rev: 5.8.0
-  hooks:
-  - id: isort
-
- repo: https://github.com/psf/black
-  rev: 21.4b1
-  hooks:
-  - id: black
-    files: ^bin/update_pythons.py|setup.py$
-
- repo: https://github.com/asottile/setup-cfg-fmt
-  rev: v1.17.0
-  hooks:
-  - id: setup-cfg-fmt
-    stages: [manual]
-
- repo: https://github.com/pre-commit/mirrors-mypy
-  rev: v0.812
-  hooks:
-  - id: mypy
-    exclude: ^(bin/|cibuildwheel/resources/).*py$
-    additional_dependencies: [packaging]
-    args: ["--python-version=3.6", "--ignore-missing-imports", "--scripts-are-modules"]
-  - id: mypy
-    name: mypy 3.7+ on bin/
-    files: ^bin/.*py$
-    additional_dependencies: [packaging]
-    args: ["--python-version=3.7", "--ignore-missing-imports", "--scripts-are-modules"]
-
 - repo: https://github.com/asottile/pyupgrade
-  rev: v2.13.0
+  rev: v2.20.0
  hooks:
  - id: pyupgrade
    name: PyUpgrade 3.6+
@@ -55,8 +25,48 @@ repos:
    exclude: ^(cibuildwheel|unit_test|test)/
    args: ["--py37-plus"]

+- repo: https://github.com/PyCQA/isort
+  rev: 5.9.1
+  hooks:
+  - id: isort
+
+- repo: https://github.com/psf/black
+  rev: 21.6b0
+  hooks:
+  - id: black
+
+- repo: https://github.com/asottile/setup-cfg-fmt
+  rev: v1.17.0
+  hooks:
+  - id: setup-cfg-fmt
+    stages: [manual]
+
+- repo: https://github.com/pre-commit/mirrors-mypy
+  rev: v0.910
+  hooks:
+  - id: mypy
+    exclude: ^(bin|cibuildwheel/resources|docs)/.*py$
+    args: ["--python-version=3.6", "--scripts-are-modules"]
+    additional_dependencies:
+      - packaging
+      - types-jinja2
+      - types-certifi
+      - types-toml
+  - id: mypy
+    name: mypy 3.7+ on bin/
+    files: ^(bin|docs)/.*py$
+    args: ["--python-version=3.7", "--scripts-are-modules"]
+    additional_dependencies:
+      - packaging>=21.0
+      - rich
+      - types-jinja2
+      - types-pyyaml
+      - types-click
+      - types-requests
+      - types-toml
+
 - repo: https://github.com/PyCQA/flake8
-  rev: 3.9.1
+  rev: 3.9.2
  hooks:
  - id: flake8
    exclude: cibuildwheel/resources/
@@ -1,36 +1,36 @@
-language: minimal
+os: linux
+dist: focal
+language: python

 branches:
  only:
-  - master
+  - main

 jobs:
  include:
    - name: Linux | x86_64 + i686 | Python 3.6
-      language: python
      python: 3.6
      services: docker
      env: PYTHON=python

    - name: Linux | arm64 | Python 3.6
-      language: python
      python: 3.6
      services: docker
-      arch: arm64
+      arch: arm64-graviton2
+      group: edge
+      virt: vm
      env: PYTHON=python

    - name: Linux | ppc64le | Python 3.6
-      language: python
      python: 3.6
      services: docker
      arch: ppc64le
-      env: PYTHON=python
-
-    - name: macOS | x86_64 | Python 3.x
-      os: osx
+      allow_failure: True
      env:
-        - PYTHON=python3
-        - PYTEST_ADDOPTS='-k "unit_test or test_0_basic" --suppress-no-test-exit-code'
+        - PYTHON=python
+        # skip test_manylinuxXXXX_only, it uses too much disk space
+        # c.f. https://travis-ci.community/t/running-out-of-disk-space-quota-when-using-docker-on-ppc64le/11634
+        - PYTEST_ADDOPTS='-k "not test_manylinuxXXXX_only"'

    - name: Windows | x86_64 | Python 3.6
      os: windows
@@ -42,18 +42,12 @@ jobs:
      env:
        - PYTHON=C:\\Python36\\python

-    - &linux_s390x_36
-      name: Linux | s390x | Python 3.6
-      language: python
+    - name: Linux | s390x | Python 3.6
      python: 3.6
      services: docker
      arch: s390x
      env: PYTHON=python

-  allow_failures:
-    # must repeat the s390x job above exactly to match
-    - *linux_s390x_36
-
 install: $PYTHON -m pip install -e ".[dev]" pytest-custom-exit-code

 script: $PYTHON ./bin/run_tests.py
@@ -1,12 +1,11 @@
 This is a summary of the Python versions and platforms covered by the different CI platforms:

-|          | 3.6                          | 3.7                                      | 3.8              |
-|----------|------------------------------|------------------------------------------|------------------|
-| Linux    | Travis CI / CircleCI         | AppVeyor² / GitHub Actions               | Azure Pipelines  |
-| macOS    | CircleCI                     | AppVeyor² / Travis CI¹ / GitHub Actions  | Azure Pipelines  |
-| Windows  | Travis CI / Azure Pipelines  | AppVeyor² / GitHub Actions               | Azure Pipelines  |
+|          | 3.6                          | 3.7                         | 3.8              |
+|----------|------------------------------|-----------------------------|------------------|
+| Linux    | Travis CI / CircleCI         | AppVeyor¹ / GitHub Actions  | Azure Pipelines  |
+| macOS    | CircleCI                     | AppVeyor¹ / GitHub Actions  | Azure Pipelines  |
+| Windows  | Travis CI / Azure Pipelines  | AppVeyor¹ / GitHub Actions  | Azure Pipelines  |

-> ¹ Python version not really pinned, but dependent on the (default) version of image used.
-> ² AppVeyor only runs the "basic" test to reduce load.
+> ¹ AppVeyor only runs the "basic" test to reduce load.

 Non-x86 architectures are covered on Travis CI using Python 3.6.
@@ -1,46 +0,0 @@
-# Contributor Covenant Code of Conduct
-
-## Our Pledge
-
-In the interest of fostering an open and welcoming environment, we as contributors and maintainers pledge to making participation in our project and our community a harassment-free experience for everyone, regardless of age, body size, disability, ethnicity, gender identity and expression, level of experience, nationality, personal appearance, race, religion, or sexual identity and orientation.
-
-## Our Standards
-
-Examples of behavior that contributes to creating a positive environment include:
-
-* Using welcoming and inclusive language
-* Being respectful of differing viewpoints and experiences
-* Gracefully accepting constructive criticism
-* Focusing on what is best for the community
-* Showing empathy towards other community members
-
-Examples of unacceptable behavior by participants include:
-
-* The use of sexualized language or imagery and unwelcome sexual attention or advances
-* Trolling, insulting/derogatory comments, and personal or political attacks
-* Public or private harassment
-* Publishing others' private information, such as a physical or electronic address, without explicit permission
-* Other conduct which could reasonably be considered inappropriate in a professional setting
-
-## Our Responsibilities
-
-Project maintainers are responsible for clarifying the standards of acceptable behavior and are expected to take appropriate and fair corrective action in response to any instances of unacceptable behavior.
-
-Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct, or to ban temporarily or permanently any contributor for other behaviors that they deem inappropriate, threatening, offensive, or harmful.
-
-## Scope
-
-This Code of Conduct applies both within project spaces and in public spaces when an individual is representing the project or its community. Examples of representing a project or community include using an official project e-mail address, posting via an official social media account, or acting as an appointed representative at an online or offline event. Representation of a project may be further defined and clarified by project maintainers.
-
-## Enforcement
-
-Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by contacting the project team at joerick@mac.com. The project team will review and investigate all complaints, and will respond in a way that it deems appropriate to the circumstances. The project team is obligated to maintain confidentiality with regard to the reporter of an incident. Further details of specific enforcement policies may be posted separately.
-
-Project maintainers who do not follow or enforce the Code of Conduct in good faith may face temporary or permanent repercussions as determined by other members of the project's leadership.
-
-## Attribution
-
-This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4, available at [http://contributor-covenant.org/version/1/4][version]
-
-[homepage]: http://contributor-covenant.org
-[version]: http://contributor-covenant.org/version/1/4/
@@ -22,7 +22,3 @@ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-
-Get-pip and Pip (bundled in cibuildwheel/resources) are licensed under the MIT
-license. See https://github.com/pypa/get-pip/blob/master/LICENSE.txt
@@ -3,11 +3,11 @@ cibuildwheel

 [![PyPI](https://img.shields.io/pypi/v/cibuildwheel.svg)](https://pypi.python.org/pypi/cibuildwheel)
 [![Documentation Status](https://readthedocs.org/projects/cibuildwheel/badge/?version=stable)](https://cibuildwheel.readthedocs.io/en/stable/?badge=stable)
-[![Actions Status](https://github.com/joerick/cibuildwheel/workflows/Test/badge.svg)](https://github.com/joerick/cibuildwheel/actions)
-[![Travis Status](https://img.shields.io/travis/joerick/cibuildwheel/master?logo=travis)](https://travis-ci.org/joerick/cibuildwheel)
-[![AppVeyor status](https://ci.appveyor.com/api/projects/status/wbsgxshp05tt1tif/branch/master?svg=true)](https://ci.appveyor.com/project/joerick/cibuildwheel/branch/master)
-[![CircleCI Status](https://img.shields.io/circleci/build/gh/joerick/cibuildwheel/master?logo=circleci)](https://circleci.com/gh/joerick/cibuildwheel)
-[![Azure Status](https://dev.azure.com/joerick0429/cibuildwheel/_apis/build/status/joerick.cibuildwheel?branchName=master)](https://dev.azure.com/joerick0429/cibuildwheel/_build/latest?definitionId=2&branchName=master)
+[![Actions Status](https://github.com/pypa/cibuildwheel/workflows/Test/badge.svg)](https://github.com/pypa/cibuildwheel/actions)
+[![Travis Status](https://img.shields.io/travis/com/pypa/cibuildwheel/main?logo=travis)](https://travis-ci.com/pypa/cibuildwheel)
+[![Appveyor status](https://ci.appveyor.com/api/projects/status/gt3vwl88yt0y3hur/branch/main?svg=true)](https://ci.appveyor.com/project/joerick/cibuildwheel/branch/main)
+[![CircleCI Status](https://img.shields.io/circleci/build/gh/pypa/cibuildwheel/main?logo=circleci)](https://circleci.com/gh/pypa/cibuildwheel)
+[![Azure Status](https://dev.azure.com/joerick0429/cibuildwheel/_apis/build/status/pypa.cibuildwheel?branchName=main)](https://dev.azure.com/joerick0429/cibuildwheel/_build/latest?definitionId=4&branchName=main)


 [Documentation](https://cibuildwheel.readthedocs.org)
@@ -23,24 +23,23 @@ What does it do?
 ----------------

 |   | macOS Intel | macOS Apple Silicon | Windows 64bit | Windows 32bit | manylinux x86_64 | manylinux i686 | manylinux aarch64 | manylinux ppc64le | manylinux s390x |
-|---|---|---|---|---|---|---|---|---|---|
-| CPython 2.7     | ✅ |   | ✅¹ | ✅¹ | ✅ | ✅ |    |    |   |
-| CPython 3.5     | ✅ |   | ✅  | ✅  | ✅ | ✅ | ✅ | ✅ | ✅ |
-| CPython 3.6     | ✅ |   | ✅  | ✅  | ✅ | ✅ | ✅ | ✅ | ✅ |
-| CPython 3.7     | ✅ |   | ✅  | ✅  | ✅ | ✅ | ✅ | ✅ | ✅ |
-| CPython 3.8     | ✅ |   | ✅  | ✅  | ✅ | ✅ | ✅ | ✅ | ✅ |
-| CPython 3.9     | ✅ | ✅ | ✅  | ✅  | ✅ | ✅ | ✅ | ✅ | ✅ |
-| PyPy 2.7 v7.3.3 | ✅ |    |    | ✅  | ✅ |    |    |    |   |
-| PyPy 3.6 v7.3.3 | ✅ |    |    | ✅  | ✅ |    |    |    |   |
-| PyPy 3.7 (beta) v7.3.3 | ✅ | |  | ✅  | ✅ |    |    |   |    |
+|---------------|----|-----|-----|-----|----|-----|----|-----|-----|
+| CPython 3.6   | ✅ | N/A | ✅  | ✅  | ✅ | ✅  | ✅ | ✅  | ✅  |
+| CPython 3.7   | ✅ | N/A | ✅  | ✅  | ✅ | ✅  | ✅ | ✅  | ✅  |
+| CPython 3.8   | ✅ | ✅  | ✅  | ✅  | ✅ | ✅  | ✅ | ✅  | ✅  |
+| CPython 3.9   | ✅ | ✅  | ✅  | ✅  | ✅ | ✅  | ✅ | ✅  | ✅  |
+| CPython 3.10¹ | ✅ | ✅  | ✅  | ✅  | ✅ | ✅  | ✅ | ✅  | ✅  |
+| PyPy 3.7 v7.3 | ✅ | N/A | ✅  | N/A | ✅ | ✅  | ✅ | N/A | N/A |

-<sup>¹ Only using a workaround with a newer compiler; Microsoft removed the 2008 compiler for Python 2.7 in April 2021.</sup><br>
+<sup>¹ Available as a prerelease under a [flag](https://cibuildwheel.readthedocs.io/en/stable/options/#prerelease-pythons)</sup><br>

 - Builds manylinux, macOS 10.9+, and Windows wheels for CPython and PyPy
 - Works on GitHub Actions, Azure Pipelines, Travis CI, AppVeyor, CircleCI, and GitLab CI
 - Bundles shared library dependencies on Linux and macOS through [auditwheel](https://github.com/pypa/auditwheel) and [delocate](https://github.com/matthew-brett/delocate)
 - Runs your library's tests against the wheel-installed version of your library

+See the [cibuildwheel 1 documentation](https://cibuildwheel.readthedocs.io/en/1.x/) if you need to build unsupported versions of Python, such as Python 2.
+
 Usage
 -----

@@ -48,9 +47,9 @@ Usage

 |                 | Linux | macOS | Windows | Linux ARM |
 |-----------------|-------|-------|---------|--------------|
-| GitHub Actions  | ✅    | ✅    | ✅      | ✅¹           |
+| GitHub Actions  | ✅    | ✅    | ✅      | ✅¹          |
 | Azure Pipelines | ✅    | ✅    | ✅      |              |
-| Travis CI       | ✅    | ✅    | ✅      | ✅           |
+| Travis CI       | ✅    |       | ✅      | ✅           |
 | AppVeyor        | ✅    | ✅    | ✅      |              |
 | CircleCI        | ✅    | ✅    |         |              |
 | Gitlab CI       | ✅    |       |         |              |
@@ -86,7 +85,7 @@ jobs:
      - uses: actions/setup-python@v2

      - name: Install cibuildwheel
-        run: python -m pip install cibuildwheel==1.10.1
+        run: python -m pip install cibuildwheel==2.0.0b1

      - name: Build wheels
        run: python -m cibuildwheel --output-dir wheelhouse
@@ -99,7 +98,7 @@ jobs:
          path: ./wheelhouse/*.whl
 ```

-For more information, including building on Python 2, PyPI deployment, and the use of other CI services or the dedicated GitHub Action, check out the [documentation](https://cibuildwheel.readthedocs.org) and the [examples](https://github.com/joerick/cibuildwheel/tree/master/examples).
+For more information, including PyPI deployment, and the use of other CI services or the dedicated GitHub Action, check out the [documentation](https://cibuildwheel.readthedocs.org) and the [examples](https://github.com/pypa/cibuildwheel/tree/main/examples).

 Options
 -------
@@ -108,13 +107,15 @@ Options
 |---|--------|-------------|
 | **Build selection** | [`CIBW_PLATFORM`](https://cibuildwheel.readthedocs.io/en/stable/options/#platform)  | Override the auto-detected target platform |
 |   | [`CIBW_BUILD`](https://cibuildwheel.readthedocs.io/en/stable/options/#build-skip)  <br> [`CIBW_SKIP`](https://cibuildwheel.readthedocs.io/en/stable/options/#build-skip)  | Choose the Python versions to build |
-|   | [`CIBW_ARCHS`](https://cibuildwheel.readthedocs.io/en/stable/options/#archs)  | Change the architectures built on your machine by default |
+|   | [`CIBW_ARCHS`](https://cibuildwheel.readthedocs.io/en/stable/options/#archs)  | Change the architectures built on your machine by default. |
 |   | [`CIBW_PROJECT_REQUIRES_PYTHON`](https://cibuildwheel.readthedocs.io/en/stable/options/#requires-python)  | Manually set the Python compatibility of your project |
-| **Build customization** | [`CIBW_ENVIRONMENT`](https://cibuildwheel.readthedocs.io/en/stable/options/#environment)  | Set environment variables needed during the build |
+|   | [`CIBW_PRERELEASE_PYTHONS`](https://cibuildwheel.readthedocs.io/en/stable/options/#prerelease-pythons)  | Enable building with pre-release versions of Python |
+| **Build customization** | [`CIBW_BUILD_FRONTEND`](https://cibuildwheel.readthedocs.io/en/stable/options/#build-frontend)  | Set the tool to use to build, either "pip" (default for now) or "build" |
+|   | [`CIBW_ENVIRONMENT`](https://cibuildwheel.readthedocs.io/en/stable/options/#environment)  | Set environment variables needed during the build |
 |   | [`CIBW_BEFORE_ALL`](https://cibuildwheel.readthedocs.io/en/stable/options/#before-all)  | Execute a shell command on the build system before any wheels are built. |
 |   | [`CIBW_BEFORE_BUILD`](https://cibuildwheel.readthedocs.io/en/stable/options/#before-build)  | Execute a shell command preparing each wheel's build |
 |   | [`CIBW_REPAIR_WHEEL_COMMAND`](https://cibuildwheel.readthedocs.io/en/stable/options/#repair-wheel-command)  | Execute a shell command to repair each (non-pure Python) built wheel |
-|   | [`CIBW_MANYLINUX_X86_64_IMAGE`](https://cibuildwheel.readthedocs.io/en/stable/options/#manylinux-image)  <br> [`CIBW_MANYLINUX_I686_IMAGE`](https://cibuildwheel.readthedocs.io/en/stable/options/#manylinux-image)  <br> [`CIBW_MANYLINUX_PYPY_X86_64_IMAGE`](https://cibuildwheel.readthedocs.io/en/stable/options/#manylinux-image)  <br> [`CIBW_MANYLINUX_AARCH64_IMAGE`](https://cibuildwheel.readthedocs.io/en/stable/options/#manylinux-image)  <br> [`CIBW_MANYLINUX_PPC64LE_IMAGE`](https://cibuildwheel.readthedocs.io/en/stable/options/#manylinux-image)  <br> [`CIBW_MANYLINUX_S390X_IMAGE`](https://cibuildwheel.readthedocs.io/en/stable/options/#manylinux-image)  | Specify alternative manylinux docker images |
+|   | [`CIBW_MANYLINUX_*_IMAGE`](https://cibuildwheel.readthedocs.io/en/stable/options/#manylinux-image)  | Specify alternative manylinux Docker images |
 |   | [`CIBW_DEPENDENCY_VERSIONS`](https://cibuildwheel.readthedocs.io/en/stable/options/#dependency-versions)  | Specify how cibuildwheel controls the versions of the tools it uses |
 | **Testing** | [`CIBW_TEST_COMMAND`](https://cibuildwheel.readthedocs.io/en/stable/options/#test-command)  | Execute a shell command to test each built wheel |
 |   | [`CIBW_BEFORE_TEST`](https://cibuildwheel.readthedocs.io/en/stable/options/#before-test)  | Execute a shell command before testing each wheel |
@@ -123,6 +124,7 @@ Options
 |   | [`CIBW_TEST_SKIP`](https://cibuildwheel.readthedocs.io/en/stable/options/#test-skip)  | Skip running tests on some builds |
 | **Other** | [`CIBW_BUILD_VERBOSITY`](https://cibuildwheel.readthedocs.io/en/stable/options/#build-verbosity)  | Increase/decrease the output of pip wheel |

+These options can be specified in a pyproject.toml file, as well; see [configuration](https://cibuildwheel.readthedocs.io/en/stable/options/#configuration).

 Working examples
 ----------------
@@ -146,48 +148,55 @@ Here are some repos that use cibuildwheel.
 | [websockets][]                    | ![travisci icon][] | ![apple icon][] ![linux icon][] | Library for building WebSocket servers and clients. Mostly written in Python, with a small C 'speedups' extension module.  |
 | [pyzmq][]                         | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Python bindings for zeromq, the networking library. Uses Cython and CFFI.  |
 | [aiortc][]                        | ![github icon][] | ![apple icon][] ![linux icon][] | WebRTC and ORTC implementation for Python using asyncio. |
-| [numexpr][]                       | ![github icon][] ![travisci icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Fast numerical array expression evaluator for Python, NumPy, PyTables, pandas, bcolz and more |
-| [coverage.py][]                   | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | The coverage tool for Python |
-| [h5py][]                          | ![azurepipelines icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | HDF5 for Python -- The h5py package is a Pythonic interface to the HDF5 binary data format. |
 | [River][]                         | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | 🌊 Online machine learning in Python |
-| [PyAV][]                          | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Pythonic bindings for FFmpeg's libraries. |
+| [coverage.py][]                   | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | The coverage tool for Python |
+| [numexpr][]                       | ![github icon][] ![travisci icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Fast numerical array expression evaluator for Python, NumPy, PyTables, pandas, bcolz and more |
+| [h5py][]                          | ![azurepipelines icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | HDF5 for Python -- The h5py package is a Pythonic interface to the HDF5 binary data format. |
 | [Dependency Injector][]           | ![travisci icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Dependency injection framework for Python, uses Windows TravisCI |
+| [PyAV][]                          | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Pythonic bindings for FFmpeg's libraries. |
 | [PyTables][]                      | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | A Python package to manage extremely large amounts of data |
 | [ruptures][]                      | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Extensive Cython + NumPy [pyproject.toml](https://github.com/deepcharles/ruptures/blob/master/pyproject.toml) example. |
 | [aioquic][]                       | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | QUIC and HTTP/3 implementation in Python |
-| [google neuroglancer][]           | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | WebGL-based viewer for volumetric data |
 | [pikepdf][]                       | ![azurepipelines icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | A Python library for reading and writing PDF, powered by qpdf |
+| [google neuroglancer][]           | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | WebGL-based viewer for volumetric data |
+| [DeepForest][]                    | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | An Efficient, Scalable and Optimized Python Framework for Deep Forest (2021.2.1) |
 | [AutoPy][]                        | ![travisci icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Includes a Windows Travis build. |
 | [Parselmouth][]                   | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | A Python interface to the Praat software package, using pybind11, C++17 and CMake, with the core Praat static library built only once and shared between wheels. |
 | [python-rapidjson][]              | ![travisci icon][] ![gitlab icon][] ![appveyor icon][] | ![windows icon][] ![linux icon][] | Python wrapper around rapidjson |
 | [Rtree][]                         | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Rtree: spatial index for Python GIS ¶ |
 | [python-snappy][]                 | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Python bindings for the snappy google library |
 | [markupsafe][]                    | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Safely add untrusted strings to HTML/XML markup. |
+| [H3-py][]                         | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Python bindings for H3, a hierarchical hexagonal geospatial indexing system |
+| [pybind11 cmake_example][]        | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Example pybind11 module built with a CMake-based build system |
 | [KDEpy][]                         | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Kernel Density Estimation in Python |
 | [cyvcf2][]                        | ![github icon][] | ![apple icon][] ![linux icon][] | cython + htslib == fast VCF and BCF processing |
-| [pybind11 cmake_example][]        | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Example pybind11 module built with a CMake-based build system |
 | [pybind11 python_example][]       | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Example pybind11 module built with a Python-based build system |
-| [sourmash][]                      | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Compute and compare MinHash signatures for DNA data sets. |
+| [sourmash][]                      | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Quickly search, compare, and analyze genomic and metagenomic data sets. |
 | [dd-trace-py][]                   | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Uses custom alternate arch emulation on GitHub |
 | [iminuit][]                       | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Jupyter-friendly Python interface for C++ MINUIT2 |
-| [jq.py][]                         | ![travisci icon][] | ![apple icon][] ![linux icon][] | Python bindings for jq |
 | [time-machine][]                  | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Time mocking library using only the CPython C API. |
-| [matrixprofile][]                 | ![travisci icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | A Python 3 library making time series data mining tasks, utilizing matrix profile algorithms, accessible to everyone. |
 | [CTranslate2][]                   | ![github icon][] | ![apple icon][] ![linux icon][] | Includes libraries from the [Intel oneAPI toolkit](https://software.intel.com/content/www/us/en/develop/tools/oneapi/base-toolkit.html). The Linux wheels also include CUDA libraries for GPU execution. |
+| [matrixprofile][]                 | ![travisci icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | A Python 3 library making time series data mining tasks, utilizing matrix profile algorithms, accessible to everyone. |
+| [jq.py][]                         | ![travisci icon][] | ![apple icon][] ![linux icon][] | Python bindings for jq |
 | [Tokenizer][]                     | ![github icon][] ![travisci icon][] | ![apple icon][] ![linux icon][] | Fast and customizable text tokenization library with BPE and SentencePiece support |
+| [PyGLM][]                         | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Fast OpenGL Mathematics (GLM) for Python |
 | [bx-python][]                     | ![travisci icon][] | ![apple icon][] ![linux icon][] | A library that includes Cython extensions. |
+| [iDynTree][]                      | ![github icon][] | ![linux icon][] | Uses manylinux_2_24 |
 | [boost-histogram][]               | ![github icon][] ![travisci icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Supports full range of wheels, including PyPy and alternate archs. |
-| [pybase64][]                      | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Fast Base64 encoding/decoding in Python |
 | [TgCrypto][]                      | ![travisci icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Includes a Windows Travis build. |
+| [pybase64][]                      | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Fast Base64 encoding/decoding in Python |
 | [etebase-py][]                    | ![travisci icon][] | ![linux icon][] | Python bindings to a Rust library using `setuptools-rust`, and `sccache` for improved speed. |
+| [fathon][]                        | ![travisci icon][] | ![apple icon][] ![linux icon][] | python package for DFA (Detrended Fluctuation Analysis) and related algorithms |
 | [pyjet][]                         | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | The interface between FastJet and NumPy |
 | [numpythia][]                     | ![github icon][] | ![apple icon][] ![linux icon][] | The interface between PYTHIA and NumPy |
-| [fathon][]                        | ![travisci icon][] | ![apple icon][] ![linux icon][] | python package for DFA (Detrended Fluctuation Analysis) and related algorithms |
-| [Imagecodecs (fork)][]            | ![azurepipelines icon][] | ![apple icon][] ![linux icon][] | Over 20 external dependencies in compiled libraries, custom docker image, `libomp`, `openblas` and `install_name_tool` for macOS. |
-| [pyinstrument_cext][]             | ![travisci icon][] ![appveyor icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | A simple C extension, without external dependencies |
 | [polaroid][]                      | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Full range of wheels for setuptools rust, with auto release and PyPI deploy. |
-| [xmlstarlet][]                    | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Python 3.6+ CFFI bindings with true MSVC build. |
+| [GSD][]                           | ![github icon][] | ![apple icon][] ![linux icon][] ![windows icon][] | Cython and NumPy project with 64-bit wheels. |
 | [pybind11 scikit_build_example][] | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | An example combining scikit-build and pybind11 |
+| [pyinstrument_cext][]             | ![travisci icon][] ![appveyor icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | A simple C extension, without external dependencies |
+| [Imagecodecs (fork)][]            | ![azurepipelines icon][] | ![apple icon][] ![linux icon][] | Over 20 external dependencies in compiled libraries, custom docker image, `libomp`, `openblas` and `install_name_tool` for macOS. |
+| [xmlstarlet][]                    | ![github icon][] | ![windows icon][] ![apple icon][] ![linux icon][] | Python 3.6+ CFFI bindings with true MSVC build. |
+| [CorrectionLib][]                 | ![github icon][] | ![apple icon][] ![linux icon][] | Structured JSON powered correction library for HEP, designed for the CMS experiment at CERN. |
+| [SiPM][]                          | ![github icon][] | ![apple icon][] ![linux icon][] | High performance library for SiPM detectors simulation using C++17, OpenMP and AVX2 intrinsics. |

 [scikit-learn]: https://github.com/scikit-learn/scikit-learn
 [Matplotlib]: https://github.com/matplotlib/matplotlib
@@ -198,48 +207,55 @@ Here are some repos that use cibuildwheel.
 [websockets]: https://github.com/aaugustin/websockets
 [pyzmq]: https://github.com/zeromq/pyzmq
 [aiortc]: https://github.com/aiortc/aiortc
-[numexpr]: https://github.com/pydata/numexpr
-[coverage.py]: https://github.com/nedbat/coveragepy
-[h5py]: https://github.com/h5py/h5py
 [River]: https://github.com/online-ml/river
-[PyAV]: https://github.com/PyAV-Org/PyAV
+[coverage.py]: https://github.com/nedbat/coveragepy
+[numexpr]: https://github.com/pydata/numexpr
+[h5py]: https://github.com/h5py/h5py
 [Dependency Injector]: https://github.com/ets-labs/python-dependency-injector
+[PyAV]: https://github.com/PyAV-Org/PyAV
 [PyTables]: https://github.com/PyTables/PyTables
 [ruptures]: https://github.com/deepcharles/ruptures
 [aioquic]: https://github.com/aiortc/aioquic
-[google neuroglancer]: https://github.com/google/neuroglancer
 [pikepdf]: https://github.com/pikepdf/pikepdf
+[google neuroglancer]: https://github.com/google/neuroglancer
+[DeepForest]: https://github.com/LAMDA-NJU/Deep-Forest
 [AutoPy]: https://github.com/autopilot-rs/autopy
 [Parselmouth]: https://github.com/YannickJadoul/Parselmouth
 [python-rapidjson]: https://github.com/python-rapidjson/python-rapidjson
 [Rtree]: https://github.com/Toblerity/rtree
 [python-snappy]: https://github.com/andrix/python-snappy
 [markupsafe]: https://github.com/pallets/markupsafe
+[H3-py]: https://github.com/uber/h3-py
+[pybind11 cmake_example]: https://github.com/pybind/cmake_example
 [KDEpy]: https://github.com/tommyod/KDEpy
 [cyvcf2]: https://github.com/brentp/cyvcf2
-[pybind11 cmake_example]: https://github.com/pybind/cmake_example
 [pybind11 python_example]: https://github.com/pybind/python_example
 [sourmash]: https://github.com/dib-lab/sourmash
 [dd-trace-py]: https://github.com/DataDog/dd-trace-py
 [iminuit]: https://github.com/scikit-hep/iminuit
-[jq.py]: https://github.com/mwilliamson/jq.py
 [time-machine]: https://github.com/adamchainz/time-machine
-[matrixprofile]: https://github.com/matrix-profile-foundation/matrixprofile
 [CTranslate2]: https://github.com/OpenNMT/CTranslate2
+[matrixprofile]: https://github.com/matrix-profile-foundation/matrixprofile
+[jq.py]: https://github.com/mwilliamson/jq.py
 [Tokenizer]: https://github.com/OpenNMT/Tokenizer
+[PyGLM]: https://github.com/Zuzu-Typ/PyGLM
 [bx-python]: https://github.com/bxlab/bx-python
+[iDynTree]: https://github.com/robotology/idyntree
 [boost-histogram]: https://github.com/scikit-hep/boost-histogram
-[pybase64]: https://github.com/mayeut/pybase64
 [TgCrypto]: https://github.com/pyrogram/tgcrypto
+[pybase64]: https://github.com/mayeut/pybase64
 [etebase-py]: https://github.com/etesync/etebase-py
+[fathon]: https://github.com/stfbnc/fathon
 [pyjet]: https://github.com/scikit-hep/pyjet
 [numpythia]: https://github.com/scikit-hep/numpythia
-[fathon]: https://github.com/stfbnc/fathon
-[Imagecodecs (fork)]: https://github.com/czaki/imagecodecs_build
-[pyinstrument_cext]: https://github.com/joerick/pyinstrument_cext
 [polaroid]: https://github.com/daggy1234/polaroid
-[xmlstarlet]: https://github.com/dimitern/xmlstarlet
+[GSD]: https://github.com/glotzerlab/gsd
 [pybind11 scikit_build_example]: https://github.com/pybind/scikit_build_example
+[pyinstrument_cext]: https://github.com/joerick/pyinstrument_cext
+[Imagecodecs (fork)]: https://github.com/czaki/imagecodecs_build
+[xmlstarlet]: https://github.com/dimitern/xmlstarlet
+[CorrectionLib]: https://github.com/cms-nanoAOD/correctionlib
+[SiPM]: https://github.com/EdoPro98/SimSiPM

 [appveyor icon]: docs/data/readme_icons/appveyor.svg
 [github icon]: docs/data/readme_icons/github.svg
@@ -251,61 +267,68 @@ Here are some repos that use cibuildwheel.
 [apple icon]: docs/data/readme_icons/apple.svg
 [linux icon]: docs/data/readme_icons/linux.svg

-<!-- scikit-learn: 44749, last pushed 0 days ago -->
-<!-- Matplotlib: 13218, last pushed 0 days ago -->
-<!-- MyPy: 10122, last pushed 0 days ago -->
-<!-- psutil: 7128, last pushed 7 days ago -->
-<!-- scikit-image: 4220, last pushed 0 days ago -->
-<!-- twisted-iocpsupport: 4184, last pushed 0 days ago -->
-<!-- websockets: 3217, last pushed 13 days ago -->
-<!-- pyzmq: 2707, last pushed 13 days ago -->
-<!-- aiortc: 2244, last pushed 0 days ago -->
-<!-- numexpr: 1548, last pushed 0 days ago -->
-<!-- coverage.py: 1515, last pushed 1 days ago -->
-<!-- h5py: 1485, last pushed 0 days ago -->
-<!-- River: 1428, last pushed 0 days ago -->
-<!-- PyAV: 1182, last pushed 2 days ago -->
-<!-- Dependency Injector: 1163, last pushed 0 days ago -->
-<!-- PyTables: 1005, last pushed 18 days ago -->
-<!-- ruptures: 637, last pushed 1 days ago -->
-<!-- aioquic: 587, last pushed 15 days ago -->
-<!-- google neuroglancer: 568, last pushed 5 days ago -->
-<!-- pikepdf: 548, last pushed 0 days ago -->
-<!-- AutoPy: 519, last pushed 175 days ago -->
-<!-- Parselmouth: 471, last pushed 0 days ago -->
-<!-- python-rapidjson: 415, last pushed 80 days ago -->
-<!-- Rtree: 388, last pushed 69 days ago -->
-<!-- python-snappy: 386, last pushed 6 days ago -->
-<!-- markupsafe: 365, last pushed 2 days ago -->
-<!-- KDEpy: 242, last pushed 16 days ago -->
-<!-- cyvcf2: 242, last pushed 17 days ago -->
-<!-- pybind11 cmake_example: 239, last pushed 77 days ago -->
-<!-- pybind11 python_example: 235, last pushed 22 days ago -->
-<!-- sourmash: 235, last pushed 0 days ago -->
-<!-- dd-trace-py: 217, last pushed 0 days ago -->
-<!-- iminuit: 172, last pushed 20 days ago -->
-<!-- jq.py: 147, last pushed 7 days ago -->
-<!-- time-machine: 139, last pushed 4 days ago -->
-<!-- matrixprofile: 138, last pushed 36 days ago -->
-<!-- CTranslate2: 133, last pushed 0 days ago -->
-<!-- Tokenizer: 126, last pushed 0 days ago -->
-<!-- bx-python: 97, last pushed 2 days ago -->
-<!-- boost-histogram: 69, last pushed 0 days ago -->
-<!-- pybase64: 56, last pushed 1 days ago -->
-<!-- TgCrypto: 52, last pushed 106 days ago -->
-<!-- etebase-py: 46, last pushed 58 days ago -->
-<!-- pyjet: 27, last pushed 7 days ago -->
-<!-- numpythia: 25, last pushed 7 days ago -->
-<!-- fathon: 22, last pushed 31 days ago -->
-<!-- Imagecodecs (fork): 16, last pushed 4 days ago -->
-<!-- pyinstrument_cext: 10, last pushed 19 days ago -->
-<!-- polaroid: 9, last pushed 0 days ago -->
-<!-- xmlstarlet: 7, last pushed 1 days ago -->
-<!-- pybind11 scikit_build_example: 4, last pushed 40 days ago -->
+<!-- scikit-learn: 46313, last pushed 0 days ago -->
+<!-- Matplotlib: 13847, last pushed 0 days ago -->
+<!-- MyPy: 10969, last pushed 0 days ago -->
+<!-- psutil: 7454, last pushed 4 days ago -->
+<!-- scikit-image: 4405, last pushed 0 days ago -->
+<!-- twisted-iocpsupport: 4293, last pushed 8 days ago -->
+<!-- websockets: 3442, last pushed 8 days ago -->
+<!-- pyzmq: 2832, last pushed 16 days ago -->
+<!-- aiortc: 2457, last pushed 23 days ago -->
+<!-- River: 1722, last pushed 5 days ago -->
+<!-- coverage.py: 1639, last pushed 11 days ago -->
+<!-- numexpr: 1600, last pushed 123 days ago -->
+<!-- h5py: 1533, last pushed 6 days ago -->
+<!-- Dependency Injector: 1422, last pushed 10 days ago -->
+<!-- PyAV: 1286, last pushed 28 days ago -->
+<!-- PyTables: 1037, last pushed 101 days ago -->
+<!-- ruptures: 749, last pushed 6 days ago -->
+<!-- aioquic: 693, last pushed 20 days ago -->
+<!-- pikepdf: 671, last pushed 4 days ago -->
+<!-- google neuroglancer: 655, last pushed 3 days ago -->
+<!-- DeepForest: 627, last pushed 34 days ago -->
+<!-- AutoPy: 544, last pushed 17 days ago -->
+<!-- Parselmouth: 524, last pushed 11 days ago -->
+<!-- python-rapidjson: 423, last pushed 9 days ago -->
+<!-- Rtree: 412, last pushed 106 days ago -->
+<!-- python-snappy: 405, last pushed 129 days ago -->
+<!-- markupsafe: 402, last pushed 2 days ago -->
+<!-- H3-py: 397, last pushed 22 days ago -->
+<!-- pybind11 cmake_example: 285, last pushed 9 days ago -->
+<!-- KDEpy: 280, last pushed 31 days ago -->
+<!-- cyvcf2: 265, last pushed 66 days ago -->
+<!-- pybind11 python_example: 255, last pushed 12 days ago -->
+<!-- sourmash: 252, last pushed 0 days ago -->
+<!-- dd-trace-py: 251, last pushed 3 days ago -->
+<!-- iminuit: 181, last pushed 0 days ago -->
+<!-- time-machine: 178, last pushed 1 days ago -->
+<!-- CTranslate2: 170, last pushed 3 days ago -->
+<!-- matrixprofile: 167, last pushed 9 days ago -->
+<!-- jq.py: 159, last pushed 12 days ago -->
+<!-- Tokenizer: 147, last pushed 9 days ago -->
+<!-- PyGLM: 105, last pushed 54 days ago -->
+<!-- bx-python: 103, last pushed 20 days ago -->
+<!-- iDynTree: 82, last pushed 19 days ago -->
+<!-- boost-histogram: 81, last pushed 4 days ago -->
+<!-- TgCrypto: 66, last pushed 35 days ago -->
+<!-- pybase64: 65, last pushed 0 days ago -->
+<!-- etebase-py: 50, last pushed 181 days ago -->
+<!-- fathon: 32, last pushed 32 days ago -->
+<!-- pyjet: 29, last pushed 46 days ago -->
+<!-- numpythia: 28, last pushed 11 days ago -->
+<!-- polaroid: 18, last pushed 6 days ago -->
+<!-- GSD: 16, last pushed 3 days ago -->
+<!-- pybind11 scikit_build_example: 14, last pushed 12 days ago -->
+<!-- pyinstrument_cext: 10, last pushed 4 days ago -->
+<!-- Imagecodecs (fork): 10, last pushed 9 days ago -->
+<!-- xmlstarlet: 7, last pushed 76 days ago -->
+<!-- CorrectionLib: 6, last pushed 12 days ago -->
+<!-- SiPM: 4, last pushed 1 days ago -->

 <!-- END bin/projects.py -->

-> Add your repo here! Let us know on [GitHub Discussions](https://github.com/joerick/cibuildwheel/discussions/485), or send a PR, adding your information to `docs/data/projects.yml`.
+> Add your repo here! Let us know on [GitHub Discussions](https://github.com/pypa/cibuildwheel/discussions/485), or send a PR, adding your information to `docs/data/projects.yml`.
 >
 > <sup>I'd like to include notes here to indicate why an example might be interesting to cibuildwheel users - the styles/technologies/techniques used in each. Please include that in future additions!</sup>

@@ -325,8 +348,48 @@ Changelog

 <!--changelog-start-->

+### v2.0.0 (prerelease)
+
+_This release is currently in prerelease. The below release notes will be condensed into a single entry when we do a final release._
+
+_v2.0.0b1 (9 July 2021)_
+
+- 🐛 Bug fixes & docs improvements
+
+_v2.0.0a4 (25 June 2021)_
+
+- 🌟 Added support for building wheels with [build](https://github.com/pypa/build), as well as pip. This feature is controlled with the [`CIBW_BUILD_FRONTEND`](https://cibuildwheel.readthedocs.io/en/latest/options/#build-frontend) option.
+
+_v2.0.0a3 (22 June 2021)_
+
+- 🌟 You can now configure cibuildwheel options inside your project's `pyproject.toml`! Environment variables still work of course. Check out the [documentation](https://cibuildwheel.readthedocs.io/en/latest/options/#setting-options) for more info.
+
+_v2.0.0a2 (1 June 2021)_
+
+- 🌟 Added the ability to test building wheels on CPython 3.10! Because CPython 3.10 is in beta, these wheels should not be distributed, because they might not be compatible with the final release, but it's available to build for testing purposes. Use the flag [`--prerelease-pythons` or `CIBW_PRERELEASE_PYTHONS`](https://cibuildwheel.readthedocs.io/en/latest/options/#prerelease-pythons) to test. (#675)
+- ✨ Added the ability to build CPython 3.8 wheels for Apple Silicon. (#704)
+- 🛠 Update to the latest build dependencies, including auditwheel 4. (#633)
+- 🛠 Use the unified pypa/manylinux images to build PyPy (#671)
+- ⚠️ Removed support for building Python 2.7 and Python 3.5 wheels, for both CPython and PyPy. If you still need to build on these versions, please use the latest v1.x version. (#596)
+
+### v1.12.0
+
+_22 June 2021_
+
+- ✨ Adds support building macOS universal2/arm64 wheels on Python 3.8.
+
+### v1.11.1
+
+_28 May 2021_
+
+- ✨ cibuildwheel is now part of the PyPA!
+- 📚 Minor docs changes, fixing links related to the above transition
+- 🛠 Update manylinux pins to the last version containing Python 2.7 and 3.5. (#674)
+
 ### v1.11.0

+_1 May 2021_
+
 - 📚 Lots of docs improvements! (#650, #623, #616, #609, #606)
 - 🐛 Fix nuget "Package is not found" error on Windows. (#653)
 - ⚠️ cibuildwheel will no longer build Windows 2.7 wheels, unless you specify a custom toolchain using `DISTUTILS_USE_SDK=1` and `MSSdk=1`. This is because Microsoft have stopped distributing Visual C++ Compiler for Python 2.7. See [this FAQ entry](https://cibuildwheel.readthedocs.io/en/stable/faq/#windows-and-python-27) for more details. (#649)
@@ -374,7 +437,7 @@ _5 February 2021_

  ```yaml
  - name: Build wheels
-    uses: joerick/cibuildwheel@version # e.g. v1.9.0
+    uses: pypa/cibuildwheel@version # e.g. v1.9.0
    with:
      output-dir: wheelhouse
    # env:
@@ -702,7 +765,7 @@ _26 May 2019_
 - 🌟 Add support for building on Azure pipelines! This lets you build all
  Linux, Mac and Windows wheels on one service, so it promises to be the
  easiest to set up! Check out the quickstart in the docs, or
-  [cibuildwheel-azure-example](https://github.com/joerick/cibuildwheel-azure-example)
+  [cibuildwheel-azure-example](https://github.com/pypa/cibuildwheel-azure-example)
  for an example project. (#126, #132)
 - 🛠 Internal change - the end-to-end test projects format was updated, so we
  can more precisely assert what should be produced for each one. (#136, #137).
@@ -857,6 +920,8 @@ Contributing

 For more info on how to contribute to cibuildwheel, see the [docs](https://cibuildwheel.readthedocs.io/en/latest/contributing/).

+Everyone interacting with the cibuildwheel project via codebase, issue tracker, chat rooms, or otherwise is expected to follow the [PSF Code of Conduct](https://github.com/pypa/.github/blob/main/CODE_OF_CONDUCT.md).
+
 Maintainers
 -----------

@@ -876,9 +941,9 @@ Credits

 Massive props also to-

- @zfrenchee for [help debugging many issues](https://github.com/joerick/cibuildwheel/issues/2)
- @lelit for some great bug reports and [contributions](https://github.com/joerick/cibuildwheel/pull/73)
- @mayeut for a [phenomenal PR](https://github.com/joerick/cibuildwheel/pull/71) patching Python itself for better compatibility!
+- @zfrenchee for [help debugging many issues](https://github.com/pypa/cibuildwheel/issues/2)
+- @lelit for some great bug reports and [contributions](https://github.com/pypa/cibuildwheel/pull/73)
+- @mayeut for a [phenomenal PR](https://github.com/pypa/cibuildwheel/pull/71) patching Python itself for better compatibility!
 - @czaki for being a super-contributor over many PRs and helping out with countless issues!
 - @mattip for his help with adding PyPy support to cibuildwheel

@@ -19,10 +19,12 @@ runs:

    # This needs powershell-core because github.action path is a Windows-style
    # path on Windows.  Powershell-core understands both types of paths.
+    # Redirecting stderr to stdout to fix interleaving issue in Actions.
    - run: >
        pipx run
        --spec ${{ github.action_path }}
        cibuildwheel
        ${{ inputs.package-dir }}
        --output-dir ${{ inputs.output-dir }}
+        2>&1
      shell: pwsh
@@ -15,19 +15,19 @@ init:
 - cmd: set PATH=C:\Python37;C:\Python37\Scripts;%PATH%
 - ps: |
      $BRANCH = if ($env:APPVEYOR_PULL_REQUEST_HEAD_REPO_BRANCH) { $env:APPVEYOR_PULL_REQUEST_HEAD_REPO_BRANCH } else { $env:APPVEYOR_REPO_BRANCH }
-      if (-not ($BRANCH -eq 'master' -or $BRANCH.ToLower().StartsWith('appveyor-'))) {
+      if (-not ($BRANCH -eq 'main' -or $BRANCH.ToLower().StartsWith('appveyor-'))) {
        $env:PYTEST_ADDOPTS='-k "unit_test or test_0_basic" --suppress-no-test-exit-code'
      }

 install: python -m pip install -e ".[dev]" pytest-custom-exit-code

 # the '-u' flag is required so the output is in the correct order.
-# See https://github.com/joerick/cibuildwheel/pull/24 for more info.
+# See https://github.com/pypa/cibuildwheel/pull/24 for more info.
 test_script: python -u ./bin/run_tests.py

 branches:
  only:
-    - master
+    - main

 skip_commits:
  files:
@@ -17,14 +17,14 @@ import cibuildwheel

 config = [
    # file path, version find/replace format
-    ('README.md', "cibuildwheel=={}"),
-    ('cibuildwheel/__init__.py', "__version__ = '{}'"),
-    ('docs/faq.md', "cibuildwheel=={}"),
-    ('docs/faq.md', "cibuildwheel@v{}"),
-    ('docs/setup.md', "cibuildwheel=={}"),
-    ('examples/*', "cibuildwheel=={}"),
-    ('examples/*', "cibuildwheel@v{}"),
-    ('setup.cfg', "version = {}"),
+    ("README.md", "cibuildwheel=={}"),
+    ("cibuildwheel/__init__.py", '__version__ = "{}"'),
+    ("docs/faq.md", "cibuildwheel=={}"),
+    ("docs/faq.md", "cibuildwheel@v{}"),
+    ("docs/setup.md", "cibuildwheel=={}"),
+    ("examples/*", "cibuildwheel=={}"),
+    ("examples/*", "cibuildwheel@v{}"),
+    ("setup.cfg", "version = {}"),
 ]

 RED = "\u001b[31m"
@@ -37,27 +37,34 @@ def bump_version() -> None:
    current_version = cibuildwheel.__version__

    try:
-        commit_date_str = subprocess.run([
-            'git',
-            'show', '--no-patch', '--pretty=format:%ci',
-            f'v{current_version}^{{commit}}',
-        ], check=True, capture_output=True, encoding='utf8').stdout
-        cd_date, cd_time, cd_tz = commit_date_str.split(' ')
+        commit_date_str = subprocess.run(
+            [
+                "git",
+                "show",
+                "--no-patch",
+                "--pretty=format:%ci",
+                f"v{current_version}^{{commit}}",
+            ],
+            check=True,
+            capture_output=True,
+            encoding="utf8",
+        ).stdout
+        cd_date, cd_time, cd_tz = commit_date_str.split(" ")

-        url_opts = urllib.parse.urlencode({'q': f'is:pr merged:>{cd_date}T{cd_time}{cd_tz}'})
-        url = f'https://github.com/joerick/cibuildwheel/pulls?{url_opts}'
+        url_opts = urllib.parse.urlencode({"q": f"is:pr merged:>{cd_date}T{cd_time}{cd_tz}"})
+        url = f"https://github.com/pypa/cibuildwheel/pulls?{url_opts}"

-        print(f'PRs merged since last release:\n  {url}')
+        print(f"PRs merged since last release:\n  {url}")
        print()
    except subprocess.CalledProcessError as e:
        print(e)
-        print('Failed to get previous version tag information.')
+        print("Failed to get previous version tag information.")

-    git_changes_result = subprocess.run(['git diff-index --quiet HEAD --'], shell=True)
+    git_changes_result = subprocess.run(["git diff-index --quiet HEAD --"], shell=True)
    repo_has_uncommitted_changes = git_changes_result.returncode != 0

    if repo_has_uncommitted_changes:
-        print('error: Uncommitted changes detected.')
+        print("error: Uncommitted changes detected.")
        sys.exit(1)

    # fmt: off
@@ -69,7 +76,7 @@ def bump_version() -> None:
        Version(new_version)
    except InvalidVersion:
        print("error: This version doesn't conform to PEP440")
-        print('       https://www.python.org/dev/peps/pep-0440/')
+        print("       https://www.python.org/dev/peps/pep-0440/")
        sys.exit(1)

    actions = []
@@ -86,11 +93,15 @@ def bump_version() -> None:
        found_at_least_one_file_needing_update = False

        for path in paths:
-            contents = path.read_text(encoding='utf8')
+            contents = path.read_text(encoding="utf8")
            if find_pattern in contents:
                found_at_least_one_file_needing_update = True
                actions.append(
-                    (path, find_pattern, replace_pattern,)
+                    (
+                        path,
+                        find_pattern,
+                        replace_pattern,
+                    )
                )

        if not found_at_least_one_file_needing_update:
@@ -103,44 +114,52 @@ def bump_version() -> None:

    for action in actions:
        path, find, replace = action
-        print(f'{path}  {RED}{find}{OFF} → {GREEN}{replace}{OFF}')
+        print(f"{path}  {RED}{find}{OFF} → {GREEN}{replace}{OFF}")

-    print(f'Then commit, and tag as v{new_version}')
+    print(f"Then commit, and tag as v{new_version}")

-    answer = input('Proceed? [y/N] ').strip()
+    answer = input("Proceed? [y/N] ").strip()

-    if answer != 'y':
-        print('Aborted')
+    if answer != "y":
+        print("Aborted")
        sys.exit(1)

    for path, find, replace in actions:
-        contents = path.read_text(encoding='utf8')
+        contents = path.read_text(encoding="utf8")
        contents = contents.replace(find, replace)
-        path.write_text(contents, encoding='utf8')
+        path.write_text(contents, encoding="utf8")

-    print('Files updated. If you want to update the changelog as part of this')
-    print('commit, do that now.')
+    print("Files updated. If you want to update the changelog as part of this")
+    print("commit, do that now.")
    print()

-    while input('Type "done" to continue: ').strip().lower() != 'done':
+    while input('Type "done" to continue: ').strip().lower() != "done":
        pass

-    subprocess.run([
-        'git', 'commit',
-        '--all',
-        f"--message='Bump version: v{new_version}'",
-    ], check=True)
+    subprocess.run(
+        [
+            "git",
+            "commit",
+            "--all",
+            f"--message=Bump version: v{new_version}",
+        ],
+        check=True,
+    )

-    subprocess.run([
-        'git', 'tag',
-        '--annotate',
-        f"--message='v{new_version}'",
-        f'v{new_version}',
-    ], check=True)
+    subprocess.run(
+        [
+            "git",
+            "tag",
+            "--annotate",
+            f"--message=v{new_version}",
+            f"v{new_version}",
+        ],
+        check=True,
+    )

-    print('Done.')
+    print("Done.")


-if __name__ == '__main__':
+if __name__ == "__main__":
    os.chdir(Path(__file__).parent.parent.resolve())
    bump_version()
@@ -17,63 +17,66 @@ def shell(cmd, **kwargs):


 def git_repo_has_changes():
-    unstaged_changes = shell('git diff-index --quiet HEAD --').returncode != 0
-    staged_changes = shell('git diff-index --quiet --cached HEAD --').returncode != 0
+    unstaged_changes = shell("git diff-index --quiet HEAD --").returncode != 0
+    staged_changes = shell("git diff-index --quiet --cached HEAD --").returncode != 0
    return unstaged_changes or staged_changes


@click.command()
 def main():
-    project_root = Path(__file__).parent / '..'
+    project_root = Path(__file__).parent / ".."
    os.chdir(project_root)

    if git_repo_has_changes():
-        print('Your git repo has uncommitted changes. Commit or stash before continuing.')
+        print("Your git repo has uncommitted changes. Commit or stash before continuing.")
        sys.exit(1)

-    previous_branch = shell('git rev-parse --abbrev-ref HEAD',
-                            check=True,
-                            capture_output=True,
-                            encoding='utf8').stdout.strip()
+    previous_branch = shell(
+        "git rev-parse --abbrev-ref HEAD", check=True, capture_output=True, encoding="utf8"
+    ).stdout.strip()

-    shell('git fetch origin', check=True)
+    shell("git fetch origin", check=True)

-    timestamp = time.strftime('%Y-%m-%dT%H-%M-%S', time.gmtime())
-    branch_name = f'update-constraints-{timestamp}'
+    timestamp = time.strftime("%Y-%m-%dT%H-%M-%S", time.gmtime())
+    branch_name = f"update-constraints-{timestamp}"

-    shell(f'git checkout -b {branch_name} origin/master', check=True)
+    shell(f"git checkout -b {branch_name} origin/main", check=True)

    try:
-        shell('bin/update_dependencies.py', check=True)
+        shell("bin/update_dependencies.py", check=True)

        if not git_repo_has_changes():
-            print('Done: no constraint updates required.')
+            print("Done: no constraint updates required.")
            return

        shell('git commit -a -m "Update dependencies"', check=True)
-        body = textwrap.dedent(f'''
-                    Update the versions of our dependencies.
+        body = textwrap.dedent(
+            f"""
+            Update the versions of our dependencies.

-                    PR generated by `{os.path.basename(__file__)}`.
-                ''')
+            PR generated by `{os.path.basename(__file__)}`.
+            """
+        )
        run(
            [
-                'gh', 'pr', 'create',
-                '--repo=joerick/cibuildwheel',
-                '--base=master',
-                "--title='Update dependencies'",
+                "gh",
+                "pr",
+                "create",
+                "--repo=pypa/cibuildwheel",
+                "--base=main",
+                "--title=Update dependencies",
                f"--body='{body}'",
            ],
-            check=True
+            check=True,
        )

-        print('Done.')
+        print("Done.")
    finally:
        # remove any local changes
-        shell('git checkout -- .')
-        shell(f'git checkout {previous_branch}', check=True)
-        shell(f'git branch -D --force {branch_name}', check=True)
+        shell("git checkout -- .")
+        shell(f"git checkout {previous_branch}", check=True)
+        shell(f"git branch -D --force {branch_name}", check=True)


-if __name__ == '__main__':
+if __name__ == "__main__":
    main.main(standalone_mode=True)
@@ -62,7 +62,7 @@ class Project:
                print(f"Broken: {self.stars_repo}")
                raise

-            self.num_stars = repo.stargazers_count
+            self.num_stars: int = repo.stargazers_count
            self.pushed_at = repo.pushed_at
            if not self.notes:
                notes = repo.description
@@ -83,9 +83,11 @@ class Project:

    @classmethod
    def header(cls) -> str:
-        return textwrap.dedent(f"""\
+        return textwrap.dedent(
+            f"""\
                | {'Name':{cls.NAME}} | CI | OS | Notes |
-                |{'':-^{cls.NAME+2  }}|----|----|:------|""")
+                |{'':-^{cls.NAME+2  }}|----|----|:------|"""
+        )

    @property
    def namelink(self) -> str:
@@ -108,7 +110,7 @@ class Project:
        return " ".join(f"![{icon} icon][]" for icon in self.os)

    def table_row(self) -> str:
-        notes = self.notes.replace('\n', ' ')
+        notes = self.notes.replace("\n", " ")
        return f"| {self.namelink: <{self.NAME}} | {self.ci_icons} | {self.os_icons} | {notes} |"

    def links(self) -> str:
@@ -120,29 +122,32 @@ class Project:


 def fetch_icon(icon_name: str) -> None:
-    url = f'https://cdn.jsdelivr.net/npm/simple-icons@v4/icons/{icon_name}.svg'
+    url = f"https://cdn.jsdelivr.net/npm/simple-icons@v4/icons/{icon_name}.svg"
    with urllib.request.urlopen(url) as f:
        original_svg_data = f.read()

    document = xml.dom.minidom.parseString(original_svg_data)
    svgElement = document.documentElement
-    assert svgElement.nodeName == 'svg'
-    svgElement.setAttribute('width', '16px')
-    svgElement.setAttribute('fill', '#606060')
+    assert svgElement.nodeName == "svg"
+    svgElement.setAttribute("width", "16px")
+    svgElement.setAttribute("fill", "#606060")

    icon_path = path_for_icon(icon_name)
    icon_path.parent.mkdir(parents=True, exist_ok=True)

-    with open(path_for_icon(icon_name), 'w') as f:
+    with open(path_for_icon(icon_name), "w") as f:
        f.write(svgElement.toxml())


 def path_for_icon(icon_name: str) -> Path:
-    return Path('.') / 'docs' / 'data' / 'readme_icons' / f'{icon_name}.svg'
+    return Path(".") / "docs" / "data" / "readme_icons" / f"{icon_name}.svg"


 def str_projects(
-    config: list[dict[str, Any]], *, online: bool = True, auth: str | None = None,
+    config: list[dict[str, Any]],
+    *,
+    online: bool = True,
+    auth: str | None = None,
 ) -> str:
    io = StringIO()
    print = functools.partial(builtins.print, file=io)
@@ -180,7 +185,10 @@ def str_projects(
@click.option("--auth", help="GitHub authentication token")
@click.option("--readme", type=click.File("r+"), help="Modify a readme file if given")
 def projects(
-    input: TextIO, online: bool, auth: str | None, readme: TextIO | None
+    input: TextIO,
+    online: bool,
+    auth: str | None,
+    readme: TextIO | None,
 ) -> None:
    config = yaml.safe_load(input)
    output = str_projects(config, online=online, auth=auth)
@@ -192,7 +200,7 @@ def projects(
        start_str = "<!-- START bin/projects.py -->\n"
        start = text.find(start_str)
        end = text.find("<!-- END bin/projects.py -->\n")
-        generated_note = f'<!-- this section is generated by bin/projects.py. Don\'t edit it directly, instead, edit {input.name} -->'
+        generated_note = f"<!-- this section is generated by bin/projects.py. Don't edit it directly, instead, edit {input.name} -->"
        new_text = f"{text[:start + len(start_str)]}\n{generated_note}\n\n{output}\n{text[end:]}"

        readme.seek(0)
@@ -21,99 +21,98 @@ def shell(cmd, **kwargs):


 def git_repo_has_changes():
-    unstaged_changes = shell('git diff-index --quiet HEAD --').returncode != 0
-    staged_changes = shell('git diff-index --quiet --cached HEAD --').returncode != 0
+    unstaged_changes = shell("git diff-index --quiet HEAD --").returncode != 0
+    staged_changes = shell("git diff-index --quiet --cached HEAD --").returncode != 0
    return unstaged_changes or staged_changes


 def generate_basic_project(path):
-    sys.path.insert(0, '')
+    sys.path.insert(0, "")
    from test.test_projects.c import new_c_project

    project = new_c_project()
    project.generate(path)


-CIService = namedtuple('CIService', 'name dst_config_path badge_md')
+CIService = namedtuple("CIService", "name dst_config_path badge_md")
 services = [
    CIService(
-        name='appveyor',
-        dst_config_path='appveyor.yml',
-        badge_md='[![Build status](https://ci.appveyor.com/api/projects/status/wbsgxshp05tt1tif/branch/{branch}?svg=true)](https://ci.appveyor.com/project/joerick/cibuildwheel/branch/{branch})',
+        name="appveyor",
+        dst_config_path="appveyor.yml",
+        badge_md="[![Build status](https://ci.appveyor.com/api/projects/status/wbsgxshp05tt1tif/branch/{branch}?svg=true)](https://ci.appveyor.com/project/pypa/cibuildwheel/branch/{branch})",
    ),
    CIService(
-        name='azure-pipelines',
-        dst_config_path='azure-pipelines.yml',
-        badge_md='[![Build Status](https://dev.azure.com/joerick0429/cibuildwheel/_apis/build/status/joerick.cibuildwheel?branchName={branch})](https://dev.azure.com/joerick0429/cibuildwheel/_build/latest?definitionId=2&branchName={branch})',
+        name="azure-pipelines",
+        dst_config_path="azure-pipelines.yml",
+        badge_md="[![Build Status](https://dev.azure.com/joerick0429/cibuildwheel/_apis/build/status/joerick.cibuildwheel?branchName={branch})](https://dev.azure.com/joerick0429/cibuildwheel/_build/latest?definitionId=2&branchName={branch})",
    ),
    CIService(
-        name='circleci',
-        dst_config_path='.circleci/config.yml',
-        badge_md='[![CircleCI](https://circleci.com/gh/joerick/cibuildwheel/tree/{branch_escaped}.svg?style=svg)](https://circleci.com/gh/joerick/cibuildwheel/tree/{branch})',
+        name="circleci",
+        dst_config_path=".circleci/config.yml",
+        badge_md="[![CircleCI](https://circleci.com/gh/pypa/cibuildwheel/tree/{branch_escaped}.svg?style=svg)](https://circleci.com/gh/pypa/cibuildwheel/tree/{branch})",
    ),
    CIService(
-        name='github',
-        dst_config_path='.github/workflows/example.yml',
-        badge_md='[![Build](https://github.com/joerick/cibuildwheel/workflows/Build/badge.svg?branch={branch})](https://github.com/joerick/cibuildwheel/actions)',
+        name="github",
+        dst_config_path=".github/workflows/example.yml",
+        badge_md="[![Build](https://github.com/pypa/cibuildwheel/workflows/Build/badge.svg?branch={branch})](https://github.com/pypa/cibuildwheel/actions)",
    ),
    CIService(
-        name='travis-ci',
-        dst_config_path='.travis.yml',
-        badge_md='[![Build Status](https://travis-ci.org/joerick/cibuildwheel.svg?branch={branch})](https://travis-ci.org/joerick/cibuildwheel)',
+        name="travis-ci",
+        dst_config_path=".travis.yml",
+        badge_md="[![Build Status](https://travis-ci.org/pypa/cibuildwheel.svg?branch={branch})](https://travis-ci.org/pypa/cibuildwheel)",
    ),
    CIService(
-        name='gitlab',
-        dst_config_path='.gitlab-ci.yml',
-        badge_md='[![Gitlab](https://gitlab.com/joerick/cibuildwheel/badges/{branch}/pipeline.svg)](https://gitlab.com/joerick/cibuildwheel/-/commits/{branch})'
+        name="gitlab",
+        dst_config_path=".gitlab-ci.yml",
+        badge_md="[![Gitlab](https://gitlab.com/pypa/cibuildwheel/badges/{branch}/pipeline.svg)](https://gitlab.com/pypa/cibuildwheel/-/commits/{branch})",
    ),
 ]


 def ci_service_for_config_file(config_file):
-    service_name = Path(config_file).name.rsplit('-', 1)[0]
+    service_name = Path(config_file).name.rsplit("-", 1)[0]

    for service in services:
        if service.name == service_name:
            return service

-    raise ValueError(f'unknown ci service for config file {config_file}')
+    raise ValueError(f"unknown ci service for config file {config_file}")


@click.command()
-@click.argument('config_files', nargs=-1, type=click.Path())
+@click.argument("config_files", nargs=-1, type=click.Path())
 def run_example_ci_configs(config_files=None):
-    '''
-        Test the example configs. If no files are specified, will test
-        examples/*-minimal.yml
-    '''
+    """
+    Test the example configs. If no files are specified, will test
+    examples/*-minimal.yml
+    """

    if len(config_files) == 0:
-        config_files = glob('examples/*-minimal.yml')
+        config_files = glob("examples/*-minimal.yml")

    # check each CI service has at most 1 config file
    configs_by_service = {}
    for config_file in config_files:
        service = ci_service_for_config_file(config_file)
        if service.name in configs_by_service:
-            raise Exception('You cannot specify more than one config per CI service')
+            raise Exception("You cannot specify more than one config per CI service")
        configs_by_service[service.name] = config_file

    if git_repo_has_changes():
-        print('Your git repo has uncommitted changes. Commit or stash before continuing.')
+        print("Your git repo has uncommitted changes. Commit or stash before continuing.")
        sys.exit(1)

-    previous_branch = shell('git rev-parse --abbrev-ref HEAD',
-                            check=True,
-                            capture_output=True,
-                            encoding='utf8').stdout.strip()
+    previous_branch = shell(
+        "git rev-parse --abbrev-ref HEAD", check=True, capture_output=True, encoding="utf8"
+    ).stdout.strip()

-    timestamp = time.strftime('%Y-%m-%dT%H-%M-%S', time.gmtime())
-    branch_name = f'example-config-test---{previous_branch}-{timestamp}'
+    timestamp = time.strftime("%Y-%m-%dT%H-%M-%S", time.gmtime())
+    branch_name = f"example-config-test---{previous_branch}-{timestamp}"

    try:
-        shell(f'git checkout --orphan {branch_name}', check=True)
+        shell(f"git checkout --orphan {branch_name}", check=True)

-        example_project = Path('example_root')
+        example_project = Path("example_root")
        generate_basic_project(example_project)

        for config_file in config_files:
@@ -124,42 +123,46 @@ def run_example_ci_configs(config_files=None):
            dst_config_file.parent.mkdir(parents=True, exist_ok=True)
            shutil.copyfile(src_config_file, dst_config_file)

-        run(['git', 'add', example_project], check=True)
-        message = textwrap.dedent(f'''
+        run(["git", "add", example_project], check=True)
+        message = textwrap.dedent(
+            f"""\
            Test example minimal configs

            Testing files: {config_files}
            Generated from branch: {previous_branch}
            Time: {timestamp}
-            ''')
-        run(['git', 'commit', '--no-verify', '--message', message], check=True)
-        shell(f'git subtree --prefix={example_project} push origin {branch_name}', check=True)
+            """
+        )
+        run(["git", "commit", "--no-verify", "--message", message], check=True)
+        shell(f"git subtree --prefix={example_project} push origin {branch_name}", check=True)

-        print('---')
+        print("---")
        print()
-        print('> **Examples test run**')
-        print('> ')
-        print(f'> Branch: [{branch_name}](https://github.com/joerick/cibuildwheel/tree/{branch_name})')
-        print('> ')
-        print('> | Service | Config | Status |')
-        print('> |---|---|---|')
+        print("> **Examples test run**")
+        print("> ")
+        print(f"> Branch: [{branch_name}](https://github.com/pypa/cibuildwheel/tree/{branch_name})")
+        print("> ")
+        print("> | Service | Config | Status |")
+        print("> |---|---|---|")
        for config_file in config_files:
            service = ci_service_for_config_file(config_file)
-            badge = service.badge_md.format(branch=branch_name, branch_escaped=quote(branch_name, safe=''))
-            print(f'> | {service.name} | `{config_file}` | {badge} |')
-        print('> ')
-        print('> Generated by `bin/run_example_ci_config.py`')
+            badge = service.badge_md.format(
+                branch=branch_name, branch_escaped=quote(branch_name, safe="")
+            )
+            print(f"> | {service.name} | `{config_file}` | {badge} |")
+        print("> ")
+        print("> Generated by `bin/run_example_ci_config.py`")
        print()
-        print('---')
+        print("---")
    finally:
        # remove any local changes
        shutil.rmtree(example_project, ignore_errors=True)
-        shell('git checkout -- .')
-        shell(f'git checkout {previous_branch}', check=True)
-        shell(f'git branch -D --force {branch_name}', check=True)
+        shell("git checkout -- .")
+        shell(f"git checkout {previous_branch}", check=True)
+        shell(f"git branch -D --force {branch_name}", check=True)


-if __name__ == '__main__':
+if __name__ == "__main__":
    os.chdir(os.path.dirname(__file__))
-    os.chdir('..')
+    os.chdir("..")
    run_example_ci_configs(standalone_mode=True)
@@ -5,16 +5,19 @@ import subprocess
 import sys
 from pathlib import Path

-if __name__ == '__main__':
+if __name__ == "__main__":
    # move cwd to the project root
    os.chdir(Path(__file__).resolve().parents[1])

    # run the unit tests
-    unit_test_args = [sys.executable, '-m', 'pytest', 'unit_test']
+    unit_test_args = [sys.executable, "-m", "pytest", "unit_test"]
    # run the docker unit tests only on Linux
-    if sys.platform.startswith('linux'):
-        unit_test_args += ['--run-docker']
+    if sys.platform.startswith("linux"):
+        unit_test_args += ["--run-docker"]
    subprocess.run(unit_test_args, check=True)

    # run the integration tests
-    subprocess.run([sys.executable, '-m', 'pytest', '-x', '--durations', '0', '--timeout=2400', 'test'], check=True)
+    subprocess.run(
+        [sys.executable, "-m", "pytest", "-x", "--durations", "0", "--timeout=2400", "test"],
+        check=True,
+    )
@@ -9,19 +9,19 @@ import sys
 import tempfile
 from pathlib import Path

-if __name__ == '__main__':
+if __name__ == "__main__":
    # move cwd to the project root
    os.chdir(Path(__file__).resolve().parents[1])

-    parser = argparse.ArgumentParser(description='Runs a sample build')
-    parser.add_argument('project_python_path', nargs='?', default='test.test_0_basic.basic_project')
+    parser = argparse.ArgumentParser(description="Runs a sample build")
+    parser.add_argument("project_python_path", nargs="?", default="test.test_0_basic.basic_project")

    options = parser.parse_args()

    project_dir = tempfile.mkdtemp()
-    subprocess.run([
-        sys.executable, '-m', 'test.test_projects',
-        options.project_python_path, project_dir
-    ], check=True)
+    subprocess.run(
+        [sys.executable, "-m", "test.test_projects", options.project_python_path, project_dir],
+        check=True,
+    )

-    sys.exit(subprocess.run([sys.executable, '-m', 'cibuildwheel'], cwd=project_dir).returncode)
+    sys.exit(subprocess.run([sys.executable, "-m", "cibuildwheel"], cwd=project_dir).returncode)
@@ -1,136 +1,40 @@
 #!/usr/bin/env python3
-from __future__ import annotations
+# This file supports 3.6+

-import configparser
 import os
 import shutil
 import subprocess
 import sys
-from typing import NamedTuple
+from pathlib import Path

-import requests
+DIR = Path(__file__).parent.resolve()
+RESOURCES = DIR.parent / "cibuildwheel/resources"

-os.chdir(os.path.dirname(__file__))
-os.chdir('..')
+python_version = "".join(str(v) for v in sys.version_info[:2])
+
+env = os.environ.copy()

 # CUSTOM_COMPILE_COMMAND is a pip-compile option that tells users how to
 # regenerate the constraints files
-os.environ['CUSTOM_COMPILE_COMMAND'] = "bin/update_dependencies.py"
+env["CUSTOM_COMPILE_COMMAND"] = "bin/update_dependencies.py"

-PYTHON_VERSIONS = ['27', '35', '36', '37', '38', '39']
+os.chdir(DIR.parent)

-if '--no-docker' in sys.argv:
-    for python_version in PYTHON_VERSIONS:
-        subprocess.run([
-            f'./env{python_version}/bin/pip-compile',
-            '--allow-unsafe',
-            '--upgrade',
-            'cibuildwheel/resources/constraints.in',
-            '--output-file=cibuildwheel/resources/constraints-python{python_version}.txt',
-        ], check=True)
-else:
-    # latest manylinux2010 image with cpython 2.7 support
-    image_runner = 'quay.io/pypa/manylinux2010_x86_64:2021-02-06-3d322a5'
-    subprocess.run(['docker', 'pull', image_runner], check=True)
-    for python_version in PYTHON_VERSIONS:
-        abi_flags = '' if int(python_version) >= 38 else 'm'
-        python_path = f'/opt/python/cp{python_version}-cp{python_version}{abi_flags}/bin/'
-        subprocess.run([
-            'docker', 'run', '--rm',
-            '-e', 'CUSTOM_COMPILE_COMMAND',
-            '-v', f'{os.getcwd()}:/volume',
-            '--workdir', '/volume', image_runner,
-            'bash', '-c',
-            f'{python_path}pip install pip-tools &&'
-            f'{python_path}pip-compile --allow-unsafe --upgrade '
-            'cibuildwheel/resources/constraints.in '
-            f'--output-file cibuildwheel/resources/constraints-python{python_version}.txt'
-        ], check=True)
+subprocess.run(
+    [
+        "pip-compile",
+        "--allow-unsafe",
+        "--upgrade",
+        "cibuildwheel/resources/constraints.in",
+        f"--output-file=cibuildwheel/resources/constraints-python{python_version}.txt",
+    ],
+    check=True,
+    env=env,
+)

 # default constraints.txt
-shutil.copyfile(f'cibuildwheel/resources/constraints-python{PYTHON_VERSIONS[-1]}.txt', 'cibuildwheel/resources/constraints.txt',)
-
-
-class Image(NamedTuple):
-    manylinux_version: str
-    platform: str
-    image_name: str
-    tag: str | None
-
-
-images = [
-    Image('manylinux1', 'x86_64', 'quay.io/pypa/manylinux1_x86_64', None),
-    Image('manylinux1', 'i686', 'quay.io/pypa/manylinux1_i686', None),
-
-    # Images for manylinux2010 are pinned to the latest tag supporting cp27
-    Image('manylinux2010', 'x86_64', 'quay.io/pypa/manylinux2010_x86_64', '2021-02-06-3d322a5'),
-    Image('manylinux2010', 'i686', 'quay.io/pypa/manylinux2010_i686', '2021-02-06-3d322a5'),
-
-    Image('manylinux2010', 'pypy_x86_64', 'pypywheels/manylinux2010-pypy_x86_64', None),
-
-    # 2014 images
-    Image('manylinux2014', 'x86_64', 'quay.io/pypa/manylinux2014_x86_64', None),
-    Image('manylinux2014', 'i686', 'quay.io/pypa/manylinux2014_i686', None),
-    Image('manylinux2014', 'aarch64', 'quay.io/pypa/manylinux2014_aarch64', None),
-    Image('manylinux2014', 'ppc64le', 'quay.io/pypa/manylinux2014_ppc64le', None),
-    Image('manylinux2014', 's390x', 'quay.io/pypa/manylinux2014_s390x', None),
-
-    # 2_24 images
-    Image('manylinux_2_24', 'x86_64', 'quay.io/pypa/manylinux_2_24_x86_64', None),
-    Image('manylinux_2_24', 'i686', 'quay.io/pypa/manylinux_2_24_i686', None),
-    Image('manylinux_2_24', 'aarch64', 'quay.io/pypa/manylinux_2_24_aarch64', None),
-    Image('manylinux_2_24', 'ppc64le', 'quay.io/pypa/manylinux_2_24_ppc64le', None),
-    Image('manylinux_2_24', 's390x', 'quay.io/pypa/manylinux_2_24_s390x', None),
-]
-
-config = configparser.ConfigParser()
-
-for image in images:
-    # get the tag name whose digest matches 'latest'
-    if image.tag is not None:
-        # image has been pinned, do not update
-        tag_name = image.tag
-    elif image.image_name.startswith('quay.io/'):
-        _, _, repository_name = image.image_name.partition('/')
-        response = requests.get(
-            f'https://quay.io/api/v1/repository/{repository_name}?includeTags=true'
-        )
-        response.raise_for_status()
-        repo_info = response.json()
-        tags_dict = repo_info['tags']
-
-        latest_tag = tags_dict.pop('latest')
-        # find the tag whose manifest matches 'latest'
-        tag_name = next(
-            name
-            for (name, info) in tags_dict.items()
-            if info['manifest_digest'] == latest_tag['manifest_digest']
-        )
-    else:
-        response = requests.get(
-            f'https://hub.docker.com/v2/repositories/{image.image_name}/tags'
-        )
-        response.raise_for_status()
-        tags = response.json()['results']
-
-        latest_tag = next(
-            tag for tag in tags if tag['name'] == 'latest'
-        )
-        # i don't know what it would mean to have multiple images per tag
-        assert len(latest_tag['images']) == 1
-        digest = latest_tag['images'][0]['digest']
-
-        pinned_tag = next(
-            tag
-            for tag in tags
-            if tag != latest_tag and tag['images'][0]['digest'] == digest
-        )
-        tag_name = pinned_tag['name']
-
-    if not config.has_section(image.platform):
-        config[image.platform] = {}
-
-    config[image.platform][image.manylinux_version] = f'{image.image_name}:{tag_name}'
-
-with open('cibuildwheel/resources/pinned_docker_images.cfg', 'w') as f:
-    config.write(f)
+if python_version == "39":
+    shutil.copyfile(
+        RESOURCES / f"constraints-python{python_version}.txt",
+        RESOURCES / "constraints.txt",
+    )
@@ -0,0 +1,93 @@
+#!/usr/bin/env python3
+from __future__ import annotations
+
+import configparser
+from pathlib import Path
+from typing import NamedTuple
+
+import requests
+
+DIR = Path(__file__).parent.resolve()
+RESOURCES = DIR.parent / "cibuildwheel/resources"
+
+
+class Image(NamedTuple):
+    manylinux_version: str
+    platform: str
+    image_name: str
+    tag: str | None  # Set this to pin the image
+
+
+images = [
+    Image("manylinux1", "x86_64", "quay.io/pypa/manylinux1_x86_64", None),
+    Image("manylinux1", "i686", "quay.io/pypa/manylinux1_i686", None),
+    # 2010 images
+    Image("manylinux2010", "x86_64", "quay.io/pypa/manylinux2010_x86_64", None),
+    Image("manylinux2010", "i686", "quay.io/pypa/manylinux2010_i686", None),
+    Image("manylinux2010", "pypy_x86_64", "quay.io/pypa/manylinux2010_x86_64", None),
+    Image("manylinux2010", "pypy_i686", "quay.io/pypa/manylinux2010_i686", None),
+    # 2014 images
+    Image("manylinux2014", "x86_64", "quay.io/pypa/manylinux2014_x86_64", None),
+    Image("manylinux2014", "i686", "quay.io/pypa/manylinux2014_i686", None),
+    Image("manylinux2014", "aarch64", "quay.io/pypa/manylinux2014_aarch64", None),
+    Image("manylinux2014", "ppc64le", "quay.io/pypa/manylinux2014_ppc64le", None),
+    Image("manylinux2014", "s390x", "quay.io/pypa/manylinux2014_s390x", None),
+    Image("manylinux2014", "pypy_x86_64", "quay.io/pypa/manylinux2014_x86_64", None),
+    Image("manylinux2014", "pypy_i686", "quay.io/pypa/manylinux2014_i686", None),
+    Image("manylinux2014", "pypy_aarch64", "quay.io/pypa/manylinux2014_aarch64", None),
+    # 2_24 images
+    Image("manylinux_2_24", "x86_64", "quay.io/pypa/manylinux_2_24_x86_64", None),
+    Image("manylinux_2_24", "i686", "quay.io/pypa/manylinux_2_24_i686", None),
+    Image("manylinux_2_24", "aarch64", "quay.io/pypa/manylinux_2_24_aarch64", None),
+    Image("manylinux_2_24", "ppc64le", "quay.io/pypa/manylinux_2_24_ppc64le", None),
+    Image("manylinux_2_24", "s390x", "quay.io/pypa/manylinux_2_24_s390x", None),
+    Image("manylinux_2_24", "pypy_x86_64", "quay.io/pypa/manylinux_2_24_x86_64", None),
+    Image("manylinux_2_24", "pypy_i686", "quay.io/pypa/manylinux_2_24_i686", None),
+    Image("manylinux_2_24", "pypy_aarch64", "quay.io/pypa/manylinux_2_24_aarch64", None),
+]
+
+config = configparser.ConfigParser()
+
+for image in images:
+    # get the tag name whose digest matches 'latest'
+    if image.tag is not None:
+        # image has been pinned, do not update
+        tag_name = image.tag
+    elif image.image_name.startswith("quay.io/"):
+        _, _, repository_name = image.image_name.partition("/")
+        response = requests.get(
+            f"https://quay.io/api/v1/repository/{repository_name}?includeTags=true"
+        )
+        response.raise_for_status()
+        repo_info = response.json()
+        tags_dict = repo_info["tags"]
+
+        latest_tag = tags_dict.pop("latest")
+        # find the tag whose manifest matches 'latest'
+        tag_name = next(
+            name
+            for (name, info) in tags_dict.items()
+            if info["manifest_digest"] == latest_tag["manifest_digest"]
+        )
+    else:
+        response = requests.get(f"https://hub.docker.com/v2/repositories/{image.image_name}/tags")
+        response.raise_for_status()
+        tags = response.json()["results"]
+
+        latest_tag = next(tag for tag in tags if tag["name"] == "latest")
+        # i don't know what it would mean to have multiple images per tag
+        assert len(latest_tag["images"]) == 1
+        digest = latest_tag["images"][0]["digest"]
+
+        pinned_tag = next(
+            tag for tag in tags if tag != latest_tag and tag["images"][0]["digest"] == digest
+        )
+        tag_name = pinned_tag["name"]
+
+    if not config.has_section(image.platform):
+        config[image.platform] = {}
+
+    config[image.platform][image.manylinux_version] = f"{image.image_name}:{tag_name}"
+
+with open(RESOURCES / "pinned_docker_images.cfg", "w") as f:
+    config.write(f)
@@ -6,7 +6,7 @@ import copy
 import difflib
 import logging
 from pathlib import Path
-from typing import Union
+from typing import Any, Union

 import click
 import requests
@@ -79,23 +79,26 @@ class WindowsVersions:
        response.raise_for_status()
        cp_info = response.json()

-        versions = (Version(v) for v in cp_info["versions"])
-        self.versions = sorted(v for v in versions if not v.is_devrelease)
+        self.version_dict = {Version(v): v for v in cp_info["versions"]}

    def update_version_windows(self, spec: Specifier) -> ConfigWinCP | None:
-        versions = sorted(v for v in self.versions if spec.contains(v))
-        if not all(v.is_prerelease for v in versions):
-            versions = [v for v in versions if not v.is_prerelease]
+
+        # Specifier.filter selects all non pre-releases that match the spec,
+        # unless there are only pre-releases, then it selects pre-releases
+        # instead (like pip)
+        unsorted_versions = spec.filter(self.version_dict)
+        versions = sorted(unsorted_versions, reverse=True)
+
        log.debug(f"Windows {self.arch} {spec} has {', '.join(str(v) for v in versions)}")

        if not versions:
            return None

-        version = versions[-1]
+        version = versions[0]
        identifier = f"cp{version.major}{version.minor}-{self.arch}"
        return ConfigWinCP(
            identifier=identifier,
-            version=str(version),
+            version=self.version_dict[version],
            arch=self.arch_str,
        )

@@ -112,30 +115,39 @@ class PyPyVersions:
            release["python_version"] = Version(release["python_version"])

        self.releases = [
-            r for r in releases if not r["pypy_version"].is_prerelease and not r["pypy_version"].is_devrelease
+            r
+            for r in releases
+            if not r["pypy_version"].is_prerelease and not r["pypy_version"].is_devrelease
        ]
        self.arch = arch_str

-    def update_version_windows(self, spec: Specifier) -> ConfigWinCP:
-        if self.arch != "32":
-            raise RuntimeError("64 bit releases not supported yet on Windows")
+    def get_arch_file(self, release: dict[str, Any]) -> str:
+        urls: list[str] = [
+            rf["download_url"]
+            for rf in release["files"]
+            if "" in rf["platform"] == f"win{self.arch}"
+        ]
+        return urls[0] if urls else ""

+    def update_version_windows(self, spec: Specifier) -> ConfigWinCP:
        releases = [r for r in self.releases if spec.contains(r["python_version"])]
-        releases = sorted(releases, key=lambda r: r["pypy_version"])
+        releases = sorted(releases, key=lambda r: r["pypy_version"])  # type: ignore
+        releases = [r for r in releases if self.get_arch_file(r)]

        if not releases:
            raise RuntimeError(f"PyPy Win {self.arch} not found for {spec}! {self.releases}")

+        version_arch = "win32" if self.arch == "32" else "win_amd64"
+
        release = releases[-1]
        version = release["python_version"]
-        identifier = f"pp{version.major}{version.minor}-win32"
-
-        (url,) = [rf["download_url"] for rf in release["files"] if "" in rf["platform"] == "win32"]
+        identifier = f"pp{version.major}{version.minor}-{version_arch}"
+        url = self.get_arch_file(release)

        return ConfigWinPP(
            identifier=identifier,
            version=f"{version.major}.{version.minor}",
-            arch="32",
+            arch=self.arch,
            url=url,
        )

@@ -144,7 +156,7 @@ class PyPyVersions:
            raise RuntimeError("Other archs not supported yet on macOS")

        releases = [r for r in self.releases if spec.contains(r["python_version"])]
-        releases = sorted(releases, key=lambda r: r["pypy_version"])
+        releases = sorted(releases, key=lambda r: r["pypy_version"])  # type: ignore

        if not releases:
            raise RuntimeError(f"PyPy macOS {self.arch} not found for {spec}!")
@@ -153,9 +165,11 @@ class PyPyVersions:
        version = release["python_version"]
        identifier = f"pp{version.major}{version.minor}-macosx_x86_64"

-        (url,) = [
-            rf["download_url"] for rf in release["files"] if "" in rf["platform"] == "darwin" and rf["arch"] == "x64"
-        ]
+        (url,) = (
+            rf["download_url"]
+            for rf in release["files"]
+            if "" in rf["platform"] == "darwin" and rf["arch"] == "x64"
+        )

        return ConfigMacOS(
            identifier=identifier,
@@ -167,7 +181,9 @@ class PyPyVersions:
 class CPythonVersions:
    def __init__(self) -> None:

-        response = requests.get("https://www.python.org/api/v2/downloads/release/?is_published=true")
+        response = requests.get(
+            "https://www.python.org/api/v2/downloads/release/?is_published=true"
+        )
        response.raise_for_status()

        releases_info = response.json()
@@ -177,29 +193,38 @@ class CPythonVersions:
            # Removing the prefix, Python 3.9 would use: release["name"].removeprefix("Python ")
            version = Version(release["name"][7:])

-            if not version.is_prerelease and not version.is_devrelease:
-                uri = int(release["resource_uri"].rstrip("/").split("/")[-1])
-                self.versions_dict[version] = uri
+            uri = int(release["resource_uri"].rstrip("/").split("/")[-1])
+            self.versions_dict[version] = uri

-    def update_version_macos(self, identifier: str, spec: Specifier) -> ConfigMacOS | None:
-        file_idents = ("macos11.pkg", "macosx10.9.pkg", "macosx10.6.pkg")
-        sorted_versions = sorted(v for v in self.versions_dict if spec.contains(v))
+    def update_version_macos(
+        self, identifier: str, version: Version, spec: Specifier
+    ) -> ConfigMacOS | None:

-        for version in reversed(sorted_versions):
+        # see note above on Specifier.filter
+        unsorted_versions = spec.filter(self.versions_dict)
+        sorted_versions = sorted(unsorted_versions, reverse=True)
+
+        if version <= Version("3.8.9999"):
+            file_ident = "macosx10.9.pkg"
+        else:
+            file_ident = "macos11.pkg"
+
+        for new_version in sorted_versions:
            # Find the first patch version that contains the requested file
-            uri = self.versions_dict[version]
-            response = requests.get(f"https://www.python.org/api/v2/downloads/release_file/?release={uri}")
+            uri = self.versions_dict[new_version]
+            response = requests.get(
+                f"https://www.python.org/api/v2/downloads/release_file/?release={uri}"
+            )
            response.raise_for_status()
            file_info = response.json()

-            for file_ident in file_idents:
-                urls = [rf["url"] for rf in file_info if file_ident in rf["url"]]
-                if urls:
-                    return ConfigMacOS(
-                        identifier=identifier,
-                        version=f"{version.major}.{version.minor}",
-                        url=urls[0],
-                    )
+            urls = [rf["url"] for rf in file_info if file_ident in rf["url"]]
+            if urls:
+                return ConfigMacOS(
+                    identifier=identifier,
+                    version=f"{new_version.major}.{new_version.minor}",
+                    url=urls[0],
+                )

        return None

@@ -212,7 +237,7 @@ class AllVersions:
    def __init__(self) -> None:
        self.windows_32 = WindowsVersions("32")
        self.windows_64 = WindowsVersions("64")
-        self.windows_pypy = PyPyVersions("32")
+        self.windows_pypy_64 = PyPyVersions("64")

        self.macos_cpython = CPythonVersions()
        self.macos_pypy = PyPyVersions("64")
@@ -223,28 +248,25 @@ class AllVersions:
        spec = Specifier(f"=={version.major}.{version.minor}.*")
        log.info(f"Reading in '{identifier}' -> {spec} @ {version}")
        orig_config = copy.copy(config)
-        config_update: AnyConfig | None
+        config_update: AnyConfig | None = None

        # We need to use ** in update due to MyPy (probably a bug)
        if "macos" in identifier:
-            if identifier.startswith("pp"):
+            if identifier.startswith("cp"):
+                config_update = self.macos_cpython.update_version_macos(identifier, version, spec)
+            elif identifier.startswith("pp"):
                config_update = self.macos_pypy.update_version_macos(spec)
-            else:
-                config_update = self.macos_cpython.update_version_macos(identifier, spec)
-
-            assert config_update is not None, f"MacOS {spec} not found!"
-            config.update(**config_update)
        elif "win32" in identifier:
-            if identifier.startswith("pp"):
-                config.update(**self.windows_pypy.update_version_windows(spec))
-            else:
+            if identifier.startswith("cp"):
                config_update = self.windows_32.update_version_windows(spec)
-                if config_update:
-                    config.update(**config_update)
        elif "win_amd64" in identifier:
-            config_update = self.windows_64.update_version_windows(spec)
-            if config_update:
-                config.update(**config_update)
+            if identifier.startswith("cp"):
+                config_update = self.windows_64.update_version_windows(spec)
+            elif identifier.startswith("pp"):
+                config_update = self.windows_pypy_64.update_version_windows(spec)
+
+        assert config_update is not None, f"{identifier} not found!"
+        config.update(**config_update)

        if config != orig_config:
            log.info(f"  Updated {orig_config} to {config}")
@@ -252,7 +274,9 @@ class AllVersions:

@click.command()
@click.option("--force", is_flag=True)
-@click.option("--level", default="INFO", type=click.Choice(["INFO", "DEBUG", "TRACE"], case_sensitive=False))
+@click.option(
+    "--level", default="INFO", type=click.Choice(["WARNING", "INFO", "DEBUG"], case_sensitive=False)
+)
 def update_pythons(force: bool, level: str) -> None:

    logging.basicConfig(
@@ -1 +1 @@
-__version__ = '1.10.1'
+__version__ = "2.0.0b1"
@@ -5,7 +5,7 @@ import textwrap
 import traceback
 from configparser import ConfigParser
 from pathlib import Path
-from typing import Dict, List, Optional, Set, Union, overload
+from typing import Dict, List, Optional, Set, Union

 from packaging.specifiers import SpecifierSet

@@ -16,9 +16,11 @@ import cibuildwheel.util
 import cibuildwheel.windows
 from cibuildwheel.architecture import Architecture, allowed_architectures_check
 from cibuildwheel.environment import EnvironmentParseError, parse_environment
+from cibuildwheel.options import ConfigOptions
 from cibuildwheel.projectfiles import get_requires_python_str
 from cibuildwheel.typing import PLATFORMS, PlatformName, assert_never
 from cibuildwheel.util import (
+    BuildFrontend,
    BuildOptions,
    BuildSelector,
    DependencyConstraints,
@@ -28,155 +30,213 @@ from cibuildwheel.util import (
    resources_dir,
 )

-
-@overload
-def get_option_from_environment(option_name: str, *, platform: Optional[str] = None, default: str) -> str: ...  # noqa: E704
-@overload
-def get_option_from_environment(option_name: str, *, platform: Optional[str] = None, default: None = None) -> Optional[str]: ...  # noqa: E704 E302
-def get_option_from_environment(option_name: str, *, platform: Optional[str] = None, default: Optional[str] = None) -> Optional[str]:  # noqa: E302
-    '''
-    Returns an option from the environment, optionally scoped by the platform.
-
-    Example:
-      get_option_from_environment('CIBW_COLOR', platform='macos')
-
-      This will return the value of CIBW_COLOR_MACOS if it exists, otherwise the value of
-      CIBW_COLOR.
-    '''
-    if platform:
-        option = os.environ.get(f'{option_name}_{platform.upper()}')
-        if option is not None:
-            return option
-
-    return os.environ.get(option_name, default)
+MANYLINUX_ARCHS = (
+    "x86_64",
+    "i686",
+    "pypy_x86_64",
+    "aarch64",
+    "ppc64le",
+    "s390x",
+    "pypy_aarch64",
+    "pypy_i686",
+)


 def main() -> None:
    platform: PlatformName

    parser = argparse.ArgumentParser(
-        description='Build wheels for all the platforms.',
-        epilog='''
-            Most options are supplied via environment variables.
-            See https://github.com/joerick/cibuildwheel#options for info.
-        ''')
+        description="Build wheels for all the platforms.",
+        epilog="""
+            Most options are supplied via environment variables or in
+            --config-file (pyproject.toml usually). See
+            https://github.com/pypa/cibuildwheel#options for info.
+        """,
+    )

-    parser.add_argument('--platform',
-                        choices=['auto', 'linux', 'macos', 'windows'],
-                        default=os.environ.get('CIBW_PLATFORM', 'auto'),
-                        help='''
-                            Platform to build for. For "linux" you need docker running, on Mac
-                            or Linux. For "macos", you need a Mac machine, and note that this
-                            script is going to automatically install MacPython on your system,
-                            so don't run on your development machine. For "windows", you need to
-                            run in Windows, and it will build and test for all versions of
-                            Python. Default: auto.
-                        ''')
+    parser.add_argument(
+        "--platform",
+        choices=["auto", "linux", "macos", "windows"],
+        default=os.environ.get("CIBW_PLATFORM", "auto"),
+        help="""
+            Platform to build for. For "linux" you need docker running, on Mac
+            or Linux. For "macos", you need a Mac machine, and note that this
+            script is going to automatically install MacPython on your system,
+            so don't run on your development machine. For "windows", you need to
+            run in Windows, and it will build and test for all versions of
+            Python. Default: auto.
+        """,
+    )

    arch_list_str = ", ".join(a.name for a in Architecture)
-    parser.add_argument('--archs',
-                        default=None,
-                        help=f'''
-                            Comma-separated list of CPU architectures to build for.
-                            When set to 'auto', builds the architectures natively supported
-                            on this machine. Set this option to build an architecture
-                            via emulation, for example, using binfmt_misc and QEMU.
-                            Default: auto.
-                            Choices: auto, auto64, auto32, native, all, {arch_list_str}
-                        ''')
+    parser.add_argument(
+        "--archs",
+        default=None,
+        help=f"""
+            Comma-separated list of CPU architectures to build for.
+            When set to 'auto', builds the architectures natively supported
+            on this machine. Set this option to build an architecture
+            via emulation, for example, using binfmt_misc and QEMU.
+            Default: auto.
+            Choices: auto, auto64, auto32, native, all, {arch_list_str}
+        """,
+    )

-    parser.add_argument('--output-dir',
-                        default=os.environ.get('CIBW_OUTPUT_DIR', 'wheelhouse'),
-                        help='Destination folder for the wheels.')
+    parser.add_argument(
+        "--output-dir",
+        help="Destination folder for the wheels.",
+    )

-    parser.add_argument('package_dir',
-                        default='.',
-                        nargs='?',
-                        help='''
-                            Path to the package that you want wheels for. Must be a subdirectory of
-                            the working directory. When set, the working directory is still
-                            considered the 'project' and is copied into the Docker container on
-                            Linux. Default: the working directory.
-                        ''')
+    parser.add_argument(
+        "--config-file",
+        help="""
+            TOML config file for cibuildwheel. Defaults to pyproject.toml, but
+            can be overridden with this option.
+        """,
+    )

-    parser.add_argument('--print-build-identifiers',
-                        action='store_true',
-                        help='Print the build identifiers matched by the current invocation and exit.')
+    parser.add_argument(
+        "package_dir",
+        default=".",
+        nargs="?",
+        help="""
+            Path to the package that you want wheels for. Must be a subdirectory of
+            the working directory. When set, the working directory is still
+            considered the 'project' and is copied into the Docker container on
+            Linux. Default: the working directory.
+        """,
+    )

-    parser.add_argument('--allow-empty',
-                        action='store_true',
-                        help='Do not report an error code if the build does not match any wheels.')
+    parser.add_argument(
+        "--print-build-identifiers",
+        action="store_true",
+        help="Print the build identifiers matched by the current invocation and exit.",
+    )
+
+    parser.add_argument(
+        "--allow-empty",
+        action="store_true",
+        help="Do not report an error code if the build does not match any wheels.",
+    )
+
+    parser.add_argument(
+        "--prerelease-pythons",
+        action="store_true",
+        help="Enable pre-release Python versions if available.",
+    )

    args = parser.parse_args()

-    detect_obsolete_options()
-
-    if args.platform != 'auto':
+    if args.platform != "auto":
        platform = args.platform
    else:
        ci_provider = detect_ci_provider()
        if ci_provider is None:
-            print(textwrap.dedent('''
-                cibuildwheel: Unable to detect platform. cibuildwheel should run on your CI server;
-                Travis CI, AppVeyor, Azure Pipelines, GitHub Actions, CircleCI, and Gitlab are
-                supported. You can run on your development machine or other CI providers using the
-                --platform argument. Check --help output for more information.
-            '''), file=sys.stderr)
+            print(
+                textwrap.dedent(
+                    """
+                    cibuildwheel: Unable to detect platform. cibuildwheel should run on your CI server;
+                    Travis CI, AppVeyor, Azure Pipelines, GitHub Actions, CircleCI, and Gitlab are
+                    supported. You can run on your development machine or other CI providers using the
+                    --platform argument. Check --help output for more information.
+                    """
+                ),
+                file=sys.stderr,
+            )
            sys.exit(2)
-        if sys.platform.startswith('linux'):
-            platform = 'linux'
-        elif sys.platform == 'darwin':
-            platform = 'macos'
-        elif sys.platform == 'win32':
-            platform = 'windows'
+        if sys.platform.startswith("linux"):
+            platform = "linux"
+        elif sys.platform == "darwin":
+            platform = "macos"
+        elif sys.platform == "win32":
+            platform = "windows"
        else:
-            print('cibuildwheel: Unable to detect platform from "sys.platform" in a CI environment. You can run '
-                  'cibuildwheel using the --platform argument. Check --help output for more information.',
-                  file=sys.stderr)
+            print(
+                'cibuildwheel: Unable to detect platform from "sys.platform" in a CI environment. You can run '
+                "cibuildwheel using the --platform argument. Check --help output for more information.",
+                file=sys.stderr,
+            )
            sys.exit(2)

    if platform not in PLATFORMS:
-        print(f'cibuildwheel: Unsupported platform: {platform}', file=sys.stderr)
+        print(f"cibuildwheel: Unsupported platform: {platform}", file=sys.stderr)
        sys.exit(2)

    package_dir = Path(args.package_dir)
-    output_dir = Path(args.output_dir)

-    if platform == 'linux':
-        repair_command_default = 'auditwheel repair -w {dest_dir} {wheel}'
-    elif platform == 'macos':
-        repair_command_default = 'delocate-listdeps {wheel} && delocate-wheel --require-archs {delocate_archs} -w {dest_dir} {wheel}'
-    elif platform == 'windows':
-        repair_command_default = ''
+    manylinux_identifiers = {
+        f"manylinux-{build_platform}-image" for build_platform in MANYLINUX_ARCHS
+    }
+    disallow = {
+        "linux": {"dependency-versions"},
+        "macos": manylinux_identifiers,
+        "windows": manylinux_identifiers,
+    }
+    options = ConfigOptions(package_dir, args.config_file, platform=platform, disallow=disallow)
+    output_dir = Path(
+        args.output_dir
+        if args.output_dir is not None
+        else os.environ.get("CIBW_OUTPUT_DIR", "wheelhouse")
+    )
+
+    build_config = options("build", env_plat=False, sep=" ") or "*"
+    skip_config = options("skip", env_plat=False, sep=" ")
+    test_skip = options("test-skip", env_plat=False, sep=" ")
+
+    archs_config_str = args.archs or options("archs", sep=" ")
+
+    build_frontend_str = options("build-frontend", env_plat=False)
+    environment_config = options("environment", table={"item": '{k}="{v}"', "sep": " "})
+    before_all = options("before-all", sep=" && ")
+    before_build = options("before-build", sep=" && ")
+    repair_command = options("repair-wheel-command", sep=" && ")
+
+    dependency_versions = options("dependency-versions")
+    test_command = options("test-command", sep=" && ")
+    before_test = options("before-test", sep=" && ")
+    test_requires = options("test-requires", sep=" ").split()
+    test_extras = options("test-extras", sep=",")
+    build_verbosity_str = options("build-verbosity")
+
+    prerelease_pythons = args.prerelease_pythons or cibuildwheel.util.strtobool(
+        os.environ.get("CIBW_PRERELEASE_PYTHONS", "0")
+    )
+
+    build_frontend: BuildFrontend
+    if build_frontend_str == "build":
+        build_frontend = "build"
+    elif build_frontend_str == "pip":
+        build_frontend = "pip"
    else:
-        assert_never(platform)
-
-    build_config = os.environ.get('CIBW_BUILD') or '*'
-    skip_config = os.environ.get('CIBW_SKIP', '')
-    test_skip = os.environ.get('CIBW_TEST_SKIP', '')
-    environment_config = get_option_from_environment('CIBW_ENVIRONMENT', platform=platform, default='')
-    before_all = get_option_from_environment('CIBW_BEFORE_ALL', platform=platform, default='')
-    before_build = get_option_from_environment('CIBW_BEFORE_BUILD', platform=platform)
-    repair_command = get_option_from_environment('CIBW_REPAIR_WHEEL_COMMAND', platform=platform, default=repair_command_default)
-    dependency_versions = get_option_from_environment('CIBW_DEPENDENCY_VERSIONS', platform=platform, default='pinned')
-    test_command = get_option_from_environment('CIBW_TEST_COMMAND', platform=platform)
-    before_test = get_option_from_environment('CIBW_BEFORE_TEST', platform=platform)
-    test_requires = get_option_from_environment('CIBW_TEST_REQUIRES', platform=platform, default='').split()
-    test_extras = get_option_from_environment('CIBW_TEST_EXTRAS', platform=platform, default='')
-    build_verbosity_str = get_option_from_environment('CIBW_BUILD_VERBOSITY', platform=platform, default='')
-
-    package_files = {'setup.py', 'setup.cfg', 'pyproject.toml'}
-
-    if not any(package_dir.joinpath(name).exists() for name in package_files):
-        names = ', '.join(sorted(package_files, reverse=True))
-        print(f'cibuildwheel: Could not find any of {{{names}}} at root of package', file=sys.stderr)
+        msg = f"cibuildwheel: Unrecognised build frontend '{build_frontend}', only 'pip' and 'build' are supported"
+        print(msg, file=sys.stderr)
        sys.exit(2)

+    package_files = {"setup.py", "setup.cfg", "pyproject.toml"}
+
+    if not any(package_dir.joinpath(name).exists() for name in package_files):
+        names = ", ".join(sorted(package_files, reverse=True))
+        msg = f"cibuildwheel: Could not find any of {{{names}}} at root of package"
+        print(msg, file=sys.stderr)
+        sys.exit(2)
+
+    # This is not supported in tool.cibuildwheel, as it comes from a standard location.
    # Passing this in as an environment variable will override pyproject.toml, setup.cfg, or setup.py
-    requires_python_str: Optional[str] = os.environ.get('CIBW_PROJECT_REQUIRES_PYTHON') or get_requires_python_str(package_dir)
+    requires_python_str: Optional[str] = os.environ.get(
+        "CIBW_PROJECT_REQUIRES_PYTHON"
+    ) or get_requires_python_str(package_dir)
    requires_python = None if requires_python_str is None else SpecifierSet(requires_python_str)

-    build_selector = BuildSelector(build_config=build_config, skip_config=skip_config, requires_python=requires_python)
+    deprecated_selectors("CIBW_BUILD", build_config, error=True)
+    deprecated_selectors("CIBW_SKIP", skip_config)
+    deprecated_selectors("CIBW_TEST_SKIP", test_skip)
+
+    build_selector = BuildSelector(
+        build_config=build_config,
+        skip_config=skip_config,
+        requires_python=requires_python,
+        prerelease_pythons=prerelease_pythons,
+    )
    test_selector = TestSelector(skip_config=test_skip)

    try:
@@ -186,16 +246,18 @@ def main() -> None:
        traceback.print_exc(None, sys.stderr)
        sys.exit(2)

-    if dependency_versions == 'pinned':
-        dependency_constraints: Optional[DependencyConstraints] = DependencyConstraints.with_defaults()
-    elif dependency_versions == 'latest':
+    if dependency_versions == "pinned":
+        dependency_constraints: Optional[
+            DependencyConstraints
+        ] = DependencyConstraints.with_defaults()
+    elif dependency_versions == "latest":
        dependency_constraints = None
    else:
        dependency_versions_path = Path(dependency_versions)
        dependency_constraints = DependencyConstraints(dependency_versions_path)

    if test_extras:
-        test_extras = f'[{test_extras}]'
+        test_extras = f"[{test_extras}]"

    try:
        build_verbosity = min(3, max(-3, int(build_verbosity_str)))
@@ -204,12 +266,7 @@ def main() -> None:

    # Add CIBUILDWHEEL environment variable
    # This needs to be passed on to the docker container in linux.py
-    os.environ['CIBUILDWHEEL'] = '1'
-
-    if args.archs is not None:
-        archs_config_str = args.archs
-    else:
-        archs_config_str = get_option_from_environment('CIBW_ARCHS', platform=platform, default='auto')
+    os.environ["CIBUILDWHEEL"] = "1"

    archs = Architecture.parse_config(archs_config_str, platform=platform)

@@ -220,9 +277,9 @@ def main() -> None:
            print(identifier)
        sys.exit(0)

-    manylinux_images: Optional[Dict[str, str]] = None
-    if platform == 'linux':
-        pinned_docker_images_file = resources_dir / 'pinned_docker_images.cfg'
+    manylinux_images: Dict[str, str] = {}
+    if platform == "linux":
+        pinned_docker_images_file = resources_dir / "pinned_docker_images.cfg"
        all_pinned_docker_images = ConfigParser()
        all_pinned_docker_images.read(pinned_docker_images_file)
        # all_pinned_docker_images looks like a dict of dicts, e.g.
@@ -231,17 +288,14 @@ def main() -> None:
        #   'pypy_x86_64': {'manylinux2010': '...' }
        #   ... }

-        manylinux_images = {}
-
-        for build_platform in ['x86_64', 'i686', 'pypy_x86_64', 'aarch64', 'ppc64le', 's390x']:
+        for build_platform in MANYLINUX_ARCHS:
            pinned_images = all_pinned_docker_images[build_platform]

-            config_name = f'CIBW_MANYLINUX_{build_platform.upper()}_IMAGE'
-            config_value = os.environ.get(config_name)
+            config_value = options(f"manylinux-{build_platform}-image")

            if config_value is None:
                # default to manylinux2010 if it's available, otherwise manylinux2014
-                image = pinned_images.get('manylinux2010') or pinned_images.get('manylinux2014')
+                image = pinned_images.get("manylinux2010") or pinned_images.get("manylinux2014")
            elif config_value in pinned_images:
                image = pinned_images[config_value]
            else:
@@ -265,7 +319,8 @@ def main() -> None:
        repair_command=repair_command,
        environment=environment,
        dependency_constraints=dependency_constraints,
-        manylinux_images=manylinux_images,
+        manylinux_images=manylinux_images or None,
+        build_frontend=build_frontend,
    )

    # Python is buffering by default when running on the CI platforms, giving problems interleaving subprocess call output with unflushed calls to 'print'
@@ -280,84 +335,83 @@ def main() -> None:
        sys.exit(4)

    if not identifiers:
-        print(f'cibuildwheel: No build identifiers selected: {build_selector}', file=sys.stderr)
+        print(f"cibuildwheel: No build identifiers selected: {build_selector}", file=sys.stderr)
        if not args.allow_empty:
            sys.exit(3)

    if not output_dir.exists():
        output_dir.mkdir(parents=True)

-    with cibuildwheel.util.print_new_wheels("\n{n} wheels produced in {m:.0f} minutes:", output_dir):
-        if platform == 'linux':
+    with cibuildwheel.util.print_new_wheels(
+        "\n{n} wheels produced in {m:.0f} minutes:", output_dir
+    ):
+        if platform == "linux":
            cibuildwheel.linux.build(build_options)
-        elif platform == 'windows':
+        elif platform == "windows":
            cibuildwheel.windows.build(build_options)
-        elif platform == 'macos':
+        elif platform == "macos":
            cibuildwheel.macos.build(build_options)
        else:
            assert_never(platform)


-def detect_obsolete_options() -> None:
-    # Check the old 'MANYLINUX1_*_IMAGE' options
-    for (deprecated, alternative) in [('CIBW_MANYLINUX1_X86_64_IMAGE', 'CIBW_MANYLINUX_X86_64_IMAGE'),
-                                      ('CIBW_MANYLINUX1_I686_IMAGE', 'CIBW_MANYLINUX_I686_IMAGE')]:
-        if deprecated in os.environ:
-            print(f"'{deprecated}' has been deprecated, and will be removed in a future release. Use the option '{alternative}' instead.")
-            if alternative not in os.environ:
-                print(f"Using value of option '{deprecated}' as replacement for '{alternative}'")
-                os.environ[alternative] = os.environ[deprecated]
-            else:
-                print(f"Option '{alternative}' is not empty. Please unset '{deprecated}'")
-                sys.exit(2)
-
-    # Check for deprecated identifiers in 'CIBW_BUILD' and 'CIBW_SKIP' options
-    for option in ['CIBW_BUILD', 'CIBW_SKIP']:
-        for deprecated, alternative in [('manylinux1', 'manylinux'),
-                                        ('macosx_10_6_intel', 'macosx_x86_64'),
-                                        ('macosx_10_9_x86_64', 'macosx_x86_64')]:
-            if option in os.environ and deprecated in os.environ[option]:
-                print(f"Build identifiers with '{deprecated}' have been deprecated. Replacing all occurences of '{deprecated}' with '{alternative}' in the option '{option}'")
-                os.environ[option] = os.environ[option].replace(deprecated, alternative)
+def deprecated_selectors(name: str, selector: str, *, error: bool = False) -> None:
+    if "p2" in selector or "p35" in selector:
+        msg = f"cibuildwheel 2.x no longer supports Python < 3.6. Please use the 1.x series or update {name}"
+        print(msg, file=sys.stderr)
+        if error:
+            sys.exit(4)


 def print_preamble(platform: str, build_options: BuildOptions) -> None:
-    print(textwrap.dedent('''
-             _ _       _ _   _       _           _
-         ___|_| |_ _ _|_| |_| |_ _ _| |_ ___ ___| |
-        |  _| | . | | | | | . | | | |   | -_| -_| |
-        |___|_|___|___|_|_|___|_____|_|_|___|___|_|
-        '''))
+    print(
+        textwrap.dedent(
+            """
+                 _ _       _ _   _       _           _
+             ___|_| |_ _ _|_| |_| |_ _ _| |_ ___ ___| |
+            |  _| | . | | | | | . | | | |   | -_| -_| |
+            |___|_|___|___|_|_|___|_____|_|_|___|___|_|
+            """
+        )
+    )

-    print(f'cibuildwheel version {cibuildwheel.__version__}\n')
+    print(f"cibuildwheel version {cibuildwheel.__version__}\n")

-    print('Build options:')
-    print(f'  platform: {platform!r}')
+    print("Build options:")
+    print(f"  platform: {platform!r}")
    for option, value in sorted(build_options._asdict().items()):
-        print(f'  {option}: {value!r}')
+        print(f"  {option}: {value!r}")

    warnings = detect_warnings(platform, build_options)
    if warnings:
-        print('\nWarnings:')
+        print("\nWarnings:")
        for warning in warnings:
-            print('  ' + warning)
+            print("  " + warning)

-    print('\nHere we go!\n')
+    print("\nHere we go!\n")


 def get_build_identifiers(
    platform: PlatformName, build_selector: BuildSelector, architectures: Set[Architecture]
 ) -> List[str]:
-    python_configurations: Union[List[cibuildwheel.linux.PythonConfiguration],
-                                 List[cibuildwheel.windows.PythonConfiguration],
-                                 List[cibuildwheel.macos.PythonConfiguration]]
+    python_configurations: Union[
+        List[cibuildwheel.linux.PythonConfiguration],
+        List[cibuildwheel.windows.PythonConfiguration],
+        List[cibuildwheel.macos.PythonConfiguration],
+    ]

-    if platform == 'linux':
-        python_configurations = cibuildwheel.linux.get_python_configurations(build_selector, architectures)
-    elif platform == 'windows':
-        python_configurations = cibuildwheel.windows.get_python_configurations(build_selector, architectures)
-    elif platform == 'macos':
-        python_configurations = cibuildwheel.macos.get_python_configurations(build_selector, architectures)
+    if platform == "linux":
+        python_configurations = cibuildwheel.linux.get_python_configurations(
+            build_selector, architectures
+        )
+    elif platform == "windows":
+        python_configurations = cibuildwheel.windows.get_python_configurations(
+            build_selector, architectures
+        )
+    elif platform == "macos":
+        python_configurations = cibuildwheel.macos.get_python_configurations(
+            build_selector, architectures
+        )
    else:
        assert_never(platform)

@@ -368,10 +422,10 @@ def detect_warnings(platform: str, build_options: BuildOptions) -> List[str]:
    warnings = []

    # warn about deprecated {python} and {pip}
-    for option_name in ['test_command', 'before_build']:
+    for option_name in ["test_command", "before_build"]:
        option_value = getattr(build_options, option_name)

-        if option_value and ('{python}' in option_value or '{pip}' in option_value):
+        if option_value and ("{python}" in option_value or "{pip}" in option_value):
            # Reminder: in an f-string, double braces means literal single brace
            msg = (
                f"{option_name}: '{{python}}' and '{{pip}}' are no longer needed, "
@@ -382,5 +436,5 @@ def detect_warnings(platform: str, build_options: BuildOptions) -> List[str]:
    return warnings


-if __name__ == '__main__':
+if __name__ == "__main__":
    main()
@@ -6,7 +6,7 @@ from typing import Set

 from .typing import Literal, PlatformName, assert_never

-PRETTY_NAMES = {'linux': 'Linux', 'macos': 'macOS', 'windows': 'Windows'}
+PRETTY_NAMES = {"linux": "Linux", "macos": "macOS", "windows": "Windows"}


@functools.total_ordering
@@ -14,81 +14,87 @@ class Architecture(Enum):
    value: str

    # mac/linux archs
-    x86_64 = 'x86_64'
+    x86_64 = "x86_64"

    # linux archs
-    i686 = 'i686'
-    aarch64 = 'aarch64'
-    ppc64le = 'ppc64le'
-    s390x = 's390x'
+    i686 = "i686"
+    aarch64 = "aarch64"
+    ppc64le = "ppc64le"
+    s390x = "s390x"

    # mac archs
-    universal2 = 'universal2'
-    arm64 = 'arm64'
+    universal2 = "universal2"
+    arm64 = "arm64"

    # windows archs
-    x86 = 'x86'
-    AMD64 = 'AMD64'
+    x86 = "x86"
+    AMD64 = "AMD64"

    # Allow this to be sorted
    def __lt__(self, other: "Architecture") -> bool:
        return self.value < other.value

    @staticmethod
-    def parse_config(config: str, platform: PlatformName) -> 'Set[Architecture]':
+    def parse_config(config: str, platform: PlatformName) -> "Set[Architecture]":
        result = set()
-        for arch_str in re.split(r'[\s,]+', config):
-            if arch_str == 'auto':
+        for arch_str in re.split(r"[\s,]+", config):
+            if arch_str == "auto":
                result |= Architecture.auto_archs(platform=platform)
-            elif arch_str == 'native':
+            elif arch_str == "native":
                result.add(Architecture(platform_module.machine()))
-            elif arch_str == 'all':
+            elif arch_str == "all":
                result |= Architecture.all_archs(platform=platform)
-            elif arch_str == 'auto64':
+            elif arch_str == "auto64":
                result |= Architecture.bitness_archs(platform=platform, bitness="64")
-            elif arch_str == 'auto32':
+            elif arch_str == "auto32":
                result |= Architecture.bitness_archs(platform=platform, bitness="32")
            else:
                result.add(Architecture(arch_str))
        return result

    @staticmethod
-    def auto_archs(platform: PlatformName) -> 'Set[Architecture]':
+    def auto_archs(platform: PlatformName) -> "Set[Architecture]":
        native_architecture = Architecture(platform_module.machine())
        result = {native_architecture}

-        if platform == 'linux' and native_architecture == Architecture.x86_64:
+        if platform == "linux" and native_architecture == Architecture.x86_64:
            # x86_64 machines can run i686 docker containers
            result.add(Architecture.i686)

-        if platform == 'windows' and native_architecture == Architecture.AMD64:
+        if platform == "windows" and native_architecture == Architecture.AMD64:
            result.add(Architecture.x86)

-        if platform == 'macos' and native_architecture == Architecture.arm64:
+        if platform == "macos" and native_architecture == Architecture.arm64:
            # arm64 can build and test both archs of a universal2 wheel.
            result.add(Architecture.universal2)

        return result

    @staticmethod
-    def all_archs(platform: PlatformName) -> 'Set[Architecture]':
-        if platform == 'linux':
-            return {Architecture.x86_64, Architecture.i686, Architecture.aarch64, Architecture.ppc64le, Architecture.s390x}
-        elif platform == 'macos':
+    def all_archs(platform: PlatformName) -> "Set[Architecture]":
+        if platform == "linux":
+            return {
+                Architecture.x86_64,
+                Architecture.i686,
+                Architecture.aarch64,
+                Architecture.ppc64le,
+                Architecture.s390x,
+            }
+        elif platform == "macos":
            return {Architecture.x86_64, Architecture.arm64, Architecture.universal2}
-        elif platform == 'windows':
+        elif platform == "windows":
            return {Architecture.x86, Architecture.AMD64}
        else:
            assert_never(platform)

    @staticmethod
-    def bitness_archs(platform: PlatformName, bitness: Literal['64', '32']) -> 'Set[Architecture]':
+    def bitness_archs(platform: PlatformName, bitness: Literal["64", "32"]) -> "Set[Architecture]":
        archs_32 = {Architecture.i686, Architecture.x86}
        auto_archs = Architecture.auto_archs(platform)

-        if bitness == '64':
+        if bitness == "64":
            return auto_archs - archs_32
-        elif bitness == '32':
+        elif bitness == "32":
            return auto_archs & archs_32
        else:
            assert_never(bitness)
@@ -101,15 +107,15 @@ def allowed_architectures_check(

    allowed_architectures = Architecture.all_archs(platform)

-    msg = f'{PRETTY_NAMES[platform]} only supports {sorted(allowed_architectures)} at the moment.'
+    msg = f"{PRETTY_NAMES[platform]} only supports {sorted(allowed_architectures)} at the moment."

-    if platform != 'linux':
-        msg += ' If you want to set emulation architectures on Linux, use CIBW_ARCHS_LINUX instead.'
+    if platform != "linux":
+        msg += " If you want to set emulation architectures on Linux, use CIBW_ARCHS_LINUX instead."

    if not architectures <= allowed_architectures:
-        msg = f'Invalid archs option {architectures}. ' + msg
+        msg = f"Invalid archs option {architectures}. " + msg
        raise ValueError(msg)

    if not architectures:
-        msg = 'Empty archs option set. ' + msg
+        msg = "Empty archs option set. " + msg
        raise ValueError(msg)
@@ -8,7 +8,9 @@ EnvironmentExecutor = Callable[[List[str], Dict[str, str]], str]


 def local_environment_executor(command: List[str], env: Dict[str, str]) -> str:
-    return subprocess.run(command, env=env, universal_newlines=True, stdout=subprocess.PIPE, check=True).stdout
+    return subprocess.run(
+        command, env=env, universal_newlines=True, stdout=subprocess.PIPE, check=True
+    ).stdout


 class NodeExecutionContext(NamedTuple):
@@ -17,11 +19,13 @@ class NodeExecutionContext(NamedTuple):
    executor: EnvironmentExecutor


-def evaluate(value: str, environment: Dict[str, str], executor: Optional[EnvironmentExecutor] = None) -> str:
+def evaluate(
+    value: str, environment: Dict[str, str], executor: Optional[EnvironmentExecutor] = None
+) -> str:
    if not value:
        # empty string evaluates to empty string
        # (but trips up bashlex)
-        return ''
+        return ""

    command_node = bashlex.parsesingle(value)

@@ -32,18 +36,20 @@ def evaluate(value: str, environment: Dict[str, str], executor: Optional[Environ

    return evaluate_node(
        value_word_node,
-        context=NodeExecutionContext(environment=environment, input=value, executor=executor or local_environment_executor)
+        context=NodeExecutionContext(
+            environment=environment, input=value, executor=executor or local_environment_executor
+        ),
    )


 def evaluate_node(node: bashlex.ast.node, context: NodeExecutionContext) -> str:
-    if node.kind == 'word':
+    if node.kind == "word":
        return evaluate_word_node(node, context=context)
-    elif node.kind == 'commandsubstitution':
+    elif node.kind == "commandsubstitution":
        node_result = evaluate_command_node(node.command, context=context)
        # bash removes training newlines in command substitution
        return node_result.rstrip()
-    elif node.kind == 'parameter':
+    elif node.kind == "parameter":
        return evaluate_parameter_node(node, context=context)
    else:
        raise ValueError(f'Unsupported bash construct: "{node.kind}"')
@@ -53,7 +59,7 @@ def evaluate_word_node(node: bashlex.ast.node, context: NodeExecutionContext) ->
    value: str = node.word

    for part in node.parts:
-        part_string = context.input[part.pos[0]:part.pos[1]]
+        part_string = context.input[part.pos[0] : part.pos[1]]
        part_value = evaluate_node(part, context=context)

        if part_string not in value:
@@ -68,23 +74,25 @@ def evaluate_word_node(node: bashlex.ast.node, context: NodeExecutionContext) ->


 def evaluate_command_node(node: bashlex.ast.node, context: NodeExecutionContext) -> str:
-    if any(n.kind == 'operator' for n in node.parts):
+    if any(n.kind == "operator" for n in node.parts):
        return evaluate_nodes_as_compound_command(node.parts, context=context)
    else:
        return evaluate_nodes_as_simple_command(node.parts, context=context)


-def evaluate_nodes_as_compound_command(nodes: Sequence[bashlex.ast.node], context: NodeExecutionContext) -> str:
+def evaluate_nodes_as_compound_command(
+    nodes: Sequence[bashlex.ast.node], context: NodeExecutionContext
+) -> str:
    # bashlex doesn't support any operators besides ';' inside command
    # substitutions, so we only need to handle that case. We do so assuming
    # that `set -o errexit` is on, because it's easier to code!

-    result = ''
+    result = ""
    for node in nodes:
-        if node.kind == 'command':
+        if node.kind == "command":
            result += evaluate_command_node(node, context=context)
-        elif node.kind == 'operator':
-            if node.op != ';':
+        elif node.kind == "operator":
+            if node.op != ";":
                raise ValueError(f'Unsupported bash operator: "{node.op}"')
        else:
            raise ValueError(f'Unsupported bash node in compound command: "{node.kind}"')
@@ -92,10 +100,12 @@ def evaluate_nodes_as_compound_command(nodes: Sequence[bashlex.ast.node], contex
    return result


-def evaluate_nodes_as_simple_command(nodes: List[bashlex.ast.node], context: NodeExecutionContext) -> str:
+def evaluate_nodes_as_simple_command(
+    nodes: List[bashlex.ast.node], context: NodeExecutionContext
+) -> str:
    command = [evaluate_node(part, context=context) for part in nodes]
    return context.executor(command, context.environment)


 def evaluate_parameter_node(node: bashlex.ast.node, context: NodeExecutionContext) -> str:
-    return context.environment.get(node.value, '')
+    return context.environment.get(node.value, "")
@@ -13,7 +13,7 @@ from .typing import PathOrStr, PopenBytes


 class DockerContainer:
-    '''
+    """
    An object that represents a running Docker container.

    Intended for use as a context manager e.g.
@@ -22,14 +22,17 @@ class DockerContainer:
    A bash shell is running in the remote container. When `call()` is invoked,
    the command is relayed to the remote shell, and the results are streamed
    back to cibuildwheel.
-    '''
-    UTILITY_PYTHON = '/opt/python/cp38-cp38/bin/python'
+    """
+
+    UTILITY_PYTHON = "/opt/python/cp38-cp38/bin/python"

    process: PopenBytes
    bash_stdin: IO[bytes]
    bash_stdout: IO[bytes]

-    def __init__(self, docker_image: str, simulate_32_bit: bool = False, cwd: Optional[PathOrStr] = None):
+    def __init__(
+        self, docker_image: str, simulate_32_bit: bool = False, cwd: Optional[PathOrStr] = None
+    ):
        if not docker_image:
            raise ValueError("Must have a non-empty docker image to run.")

@@ -38,27 +41,30 @@ class DockerContainer:
        self.cwd = cwd
        self.name: Optional[str] = None

-    def __enter__(self) -> 'DockerContainer':
-        self.name = f'cibuildwheel-{uuid.uuid4()}'
-        cwd_args = ['-w', str(self.cwd)] if self.cwd else []
-        shell_args = ['linux32', '/bin/bash'] if self.simulate_32_bit else ['/bin/bash']
+    def __enter__(self) -> "DockerContainer":
+        self.name = f"cibuildwheel-{uuid.uuid4()}"
+        cwd_args = ["-w", str(self.cwd)] if self.cwd else []
+        shell_args = ["linux32", "/bin/bash"] if self.simulate_32_bit else ["/bin/bash"]
        subprocess.run(
            [
-                'docker', 'create',
-                '--env=CIBUILDWHEEL',
-                f'--name={self.name}',
-                '--interactive',
-                '--volume=/:/host',  # ignored on CircleCI
+                "docker",
+                "create",
+                "--env=CIBUILDWHEEL",
+                f"--name={self.name}",
+                "--interactive",
+                "--volume=/:/host",  # ignored on CircleCI
                *cwd_args,
                self.docker_image,
-                *shell_args
+                *shell_args,
            ],
            check=True,
        )
        self.process = subprocess.Popen(
            [
-                'docker', 'start',
-                '--attach', '--interactive',
+                "docker",
+                "start",
+                "--attach",
+                "--interactive",
                self.name,
            ],
            stdin=subprocess.PIPE,
@@ -70,15 +76,16 @@ class DockerContainer:
        self.bash_stdout = self.process.stdout

        # run a noop command to block until the container is responding
-        self.call(['/bin/true'])
+        self.call(["/bin/true"])

        return self

    def __exit__(
-            self,
-            exc_type: Optional[Type[BaseException]],
-            exc_val: Optional[BaseException],
-            exc_tb: Optional[TracebackType]) -> None:
+        self,
+        exc_type: Optional[Type[BaseException]],
+        exc_val: Optional[BaseException],
+        exc_tb: Optional[TracebackType],
+    ) -> None:

        self.bash_stdin.close()
        self.process.terminate()
@@ -86,7 +93,7 @@ class DockerContainer:

        assert isinstance(self.name, str)

-        subprocess.run(['docker', 'rm', '--force', '-v', self.name], stdout=subprocess.DEVNULL)
+        subprocess.run(["docker", "rm", "--force", "-v", self.name], stdout=subprocess.DEVNULL)
        self.name = None

    def copy_into(self, from_path: Path, to_path: PurePath) -> None:
@@ -96,55 +103,66 @@ class DockerContainer:
        # Use `docker exec` instead.

        if from_path.is_dir():
-            self.call(['mkdir', '-p', to_path])
+            self.call(["mkdir", "-p", to_path])
            subprocess.run(
-                f'tar cf - . | docker exec -i {self.name} tar -xC {shell_quote(to_path)} -f -',
+                f"tar cf - . | docker exec -i {self.name} tar -xC {shell_quote(to_path)} -f -",
                shell=True,
                check=True,
-                cwd=from_path)
+                cwd=from_path,
+            )
        else:
            subprocess.run(
                f'cat {shell_quote(from_path)} | docker exec -i {self.name} sh -c "cat > {shell_quote(to_path)}"',
                shell=True,
-                check=True)
+                check=True,
+            )

    def copy_out(self, from_path: PurePath, to_path: Path) -> None:
        # note: we assume from_path is a dir
        to_path.mkdir(parents=True, exist_ok=True)

        subprocess.run(
-            f'docker exec -i {self.name} tar -cC {shell_quote(from_path)} -f - . | tar -xf -',
+            f"docker exec -i {self.name} tar -cC {shell_quote(from_path)} -f - . | tar -xf -",
            shell=True,
            check=True,
-            cwd=to_path
+            cwd=to_path,
        )

    def glob(self, path: PurePath, pattern: str) -> List[PurePath]:
        glob_pattern = os.path.join(str(path), pattern)

-        path_strs = json.loads(self.call([
-            self.UTILITY_PYTHON,
-            '-c',
-            f'import sys, json, glob; json.dump(glob.glob({glob_pattern!r}), sys.stdout)'
-        ], capture_output=True))
+        path_strs = json.loads(
+            self.call(
+                [
+                    self.UTILITY_PYTHON,
+                    "-c",
+                    f"import sys, json, glob; json.dump(glob.glob({glob_pattern!r}), sys.stdout)",
+                ],
+                capture_output=True,
+            )
+        )

        return [PurePath(p) for p in path_strs]

    def call(
-            self,
-            args: Sequence[PathOrStr],
-            env: Optional[Dict[str, str]] = None,
-            capture_output: bool = False,
-            cwd: Optional[PathOrStr] = None) -> str:
+        self,
+        args: Sequence[PathOrStr],
+        env: Optional[Dict[str, str]] = None,
+        capture_output: bool = False,
+        cwd: Optional[PathOrStr] = None,
+    ) -> str:

-        chdir = f'cd {cwd}' if cwd else ''
-        env_assignments = ' '.join(f'{shlex.quote(k)}={shlex.quote(v)}'
-                                   for k, v in env.items()) if env is not None else ''
-        command = ' '.join(shlex.quote(str(a)) for a in args)
+        chdir = f"cd {cwd}" if cwd else ""
+        env_assignments = (
+            " ".join(f"{shlex.quote(k)}={shlex.quote(v)}" for k, v in env.items())
+            if env is not None
+            else ""
+        )
+        command = " ".join(shlex.quote(str(a)) for a in args)
        end_of_message = str(uuid.uuid4())

        # log the command we're executing
-        print(f'    + {command}')
+        print(f"    + {command}")

        # Write a command to the remote shell. First we change the
        # cwd, if that's required. Then, we use the `env` utility to run
@@ -153,12 +171,18 @@ class DockerContainer:
        # Finally, the remote shell is told to write a footer - this will show
        # up in the output so we know when to stop reading, and will include
        # the returncode of `command`.
-        self.bash_stdin.write(bytes(f'''(
+        self.bash_stdin.write(
+            bytes(
+                f"""(
            {chdir}
            env {env_assignments} {command}
            printf "%04d%s\n" $? {end_of_message}
        )
-        ''', encoding='utf8', errors='surrogateescape'))
+        """,
+                encoding="utf8",
+                errors="surrogateescape",
+            )
+        )
        self.bash_stdin.flush()

        if capture_output:
@@ -169,7 +193,7 @@ class DockerContainer:
        while True:
            line = self.bash_stdout.readline()

-            if line.endswith(bytes(end_of_message, encoding='utf8') + b'\n'):
+            if line.endswith(bytes(end_of_message, encoding="utf8") + b"\n"):
                # fmt: off
                footer_offset = (
                    len(line)
@@ -178,7 +202,7 @@ class DockerContainer:
                    - 4  # 4 returncode decimals
                )
                # fmt: on
-                returncode_str = line[footer_offset:footer_offset+4]
+                returncode_str = line[footer_offset : footer_offset + 4]
                returncode = int(returncode_str)
                # add the last line to output, without the footer
                output_io.write(line[0:footer_offset])
@@ -187,9 +211,9 @@ class DockerContainer:
                output_io.write(line)

        if isinstance(output_io, io.BytesIO):
-            output = str(output_io.getvalue(), encoding='utf8', errors='surrogateescape')
+            output = str(output_io.getvalue(), encoding="utf8", errors="surrogateescape")
        else:
-            output = ''
+            output = ""

        if returncode != 0:
            raise subprocess.CalledProcessError(returncode, args, output)
@@ -197,11 +221,16 @@ class DockerContainer:
        return output

    def get_environment(self) -> Dict[str, str]:
-        env = json.loads(self.call([
-            self.UTILITY_PYTHON,
-            '-c',
-            'import sys, json, os; json.dump(os.environ.copy(), sys.stdout)'
-        ], capture_output=True))
+        env = json.loads(
+            self.call(
+                [
+                    self.UTILITY_PYTHON,
+                    "-c",
+                    "import sys, json, os; json.dump(os.environ.copy(), sys.stdout)",
+                ],
+                capture_output=True,
+            )
+        )
        return cast(Dict[str, str], env)

    def environment_executor(self, command: List[str], environment: Dict[str, str]) -> str:
@@ -10,7 +10,7 @@ class EnvironmentParseError(Exception):


 def split_env_items(env_string: str) -> List[str]:
-    '''Splits space-separated variable assignments into a list of individual assignments.
+    """Splits space-separated variable assignments into a list of individual assignments.

    >>> split_env_items('VAR=abc')
    ['VAR=abc']
@@ -24,7 +24,7 @@ def split_env_items(env_string: str) -> List[str]:
    ['PATH="$PATH;/opt/cibw_test_path"']
    >>> split_env_items('PATH2="something with spaces"')
    ['PATH2="something with spaces"']
-    '''
+    """
    if not env_string:
        return []

@@ -32,7 +32,7 @@ def split_env_items(env_string: str) -> List[str]:
    result = []

    for word_node in command_node.parts:
-        part_string = env_string[word_node.pos[0]:word_node.pos[1]]
+        part_string = env_string[word_node.pos[0] : word_node.pos[1]]
        result.append(part_string)

    return result
@@ -40,30 +40,36 @@ def split_env_items(env_string: str) -> List[str]:

 class EnvironmentAssignment:
    def __init__(self, assignment: str):
-        name, equals, value = assignment.partition('=')
+        name, equals, value = assignment.partition("=")
        if not equals:
            raise EnvironmentParseError(assignment)
        self.name = name
        self.value = value

-    def evaluated_value(self, environment: Dict[str, str], executor: Optional[bashlex_eval.EnvironmentExecutor] = None) -> str:
-        '''Returns the value of this assignment, as evaluated in the environment'''
+    def evaluated_value(
+        self,
+        environment: Dict[str, str],
+        executor: Optional[bashlex_eval.EnvironmentExecutor] = None,
+    ) -> str:
+        """Returns the value of this assignment, as evaluated in the environment"""
        return bashlex_eval.evaluate(self.value, environment=environment, executor=executor)

    def as_shell_assignment(self) -> str:
-        return f'export {self.name}={self.value}'
+        return f"export {self.name}={self.value}"

    def __repr__(self) -> str:
-        return f'{self.name}={self.value}'
+        return f"{self.name}={self.value}"


 class ParsedEnvironment:
    def __init__(self, assignments: List[EnvironmentAssignment]):
        self.assignments = assignments

-    def as_dictionary(self,
-                      prev_environment: Mapping[str, str],
-                      executor: Optional[bashlex_eval.EnvironmentExecutor] = None) -> Dict[str, str]:
+    def as_dictionary(
+        self,
+        prev_environment: Mapping[str, str],
+        executor: Optional[bashlex_eval.EnvironmentExecutor] = None,
+    ) -> Dict[str, str]:
        environment = dict(**prev_environment)

        for assignment in self.assignments:
@@ -76,7 +82,7 @@ class ParsedEnvironment:
        return [a.as_shell_assignment() for a in self.assignments]

    def __repr__(self) -> str:
-        return f'ParsedEnvironment({[repr(a) for a in self.assignments]!r})'
+        return f"ParsedEnvironment({[repr(a) for a in self.assignments]!r})"


 def parse_environment(env_string: str) -> ParsedEnvironment:
@@ -7,7 +7,7 @@ from typing import List, NamedTuple, Set
 from .architecture import Architecture
 from .docker_container import DockerContainer
 from .logger import log
-from .typing import PathOrStr
+from .typing import PathOrStr, assert_never
 from .util import (
    BuildOptions,
    BuildSelector,
@@ -15,7 +15,6 @@ from .util import (
    get_build_verbosity_extra_flags,
    prepare_command,
    read_python_configs,
-    resources_dir,
 )


@@ -34,14 +33,15 @@ def get_python_configurations(
    architectures: Set[Architecture],
 ) -> List[PythonConfiguration]:

-    full_python_configs = read_python_configs('linux')
+    full_python_configs = read_python_configs("linux")

    python_configurations = [PythonConfiguration(**item) for item in full_python_configs]

    # return all configurations whose arch is in our `architectures` set,
    # and match the build/skip rules
    return [
-        c for c in python_configurations
+        c
+        for c in python_configurations
        if any(c.identifier.endswith(arch.value) for arch in architectures)
        and build_selector(c.identifier)
    ]
@@ -50,154 +50,216 @@ def get_python_configurations(
 def build(options: BuildOptions) -> None:
    try:
        # check docker is installed
-        subprocess.run(['docker', '--version'], check=True, stdout=subprocess.DEVNULL)
+        subprocess.run(["docker", "--version"], check=True, stdout=subprocess.DEVNULL)
    except Exception:
-        print('cibuildwheel: Docker not found. Docker is required to run Linux builds. '
-              'If you\'re building on Travis CI, add `services: [docker]` to your .travis.yml.'
-              'If you\'re building on Circle CI in Linux, add a `setup_remote_docker` step to your .circleci/config.yml',
-              file=sys.stderr)
+        print(
+            "cibuildwheel: Docker not found. Docker is required to run Linux builds. "
+            "If you're building on Travis CI, add `services: [docker]` to your .travis.yml."
+            "If you're building on Circle CI in Linux, add a `setup_remote_docker` step to your .circleci/config.yml",
+            file=sys.stderr,
+        )
        sys.exit(2)

    assert options.manylinux_images is not None
    python_configurations = get_python_configurations(options.build_selector, options.architectures)
    platforms = [
-        ('cp', 'manylinux_x86_64', options.manylinux_images['x86_64']),
-        ('cp', 'manylinux_i686', options.manylinux_images['i686']),
-        ('cp', 'manylinux_aarch64', options.manylinux_images['aarch64']),
-        ('cp', 'manylinux_ppc64le', options.manylinux_images['ppc64le']),
-        ('cp', 'manylinux_s390x', options.manylinux_images['s390x']),
-        ('pp', 'manylinux_x86_64', options.manylinux_images['pypy_x86_64']),
+        ("cp", "manylinux_x86_64", options.manylinux_images["x86_64"]),
+        ("cp", "manylinux_i686", options.manylinux_images["i686"]),
+        ("cp", "manylinux_aarch64", options.manylinux_images["aarch64"]),
+        ("cp", "manylinux_ppc64le", options.manylinux_images["ppc64le"]),
+        ("cp", "manylinux_s390x", options.manylinux_images["s390x"]),
+        ("pp", "manylinux_x86_64", options.manylinux_images["pypy_x86_64"]),
+        ("pp", "manylinux_aarch64", options.manylinux_images["pypy_aarch64"]),
+        ("pp", "manylinux_i686", options.manylinux_images["pypy_i686"]),
    ]

    cwd = Path.cwd()
    abs_package_dir = options.package_dir.resolve()
    if cwd != abs_package_dir and cwd not in abs_package_dir.parents:
-        raise Exception('package_dir must be inside the working directory')
+        raise Exception("package_dir must be inside the working directory")

-    container_project_path = PurePath('/project')
+    container_project_path = PurePath("/project")
    container_package_dir = container_project_path / abs_package_dir.relative_to(cwd)
-    container_output_dir = PurePath('/output')
+    container_output_dir = PurePath("/output")

    for implementation, platform_tag, docker_image in platforms:
-        platform_configs = [c for c in python_configurations if c.identifier.startswith(implementation) and c.identifier.endswith(platform_tag)]
+        platform_configs = [
+            c
+            for c in python_configurations
+            if c.identifier.startswith(implementation) and c.identifier.endswith(platform_tag)
+        ]
        if not platform_configs:
            continue

        try:
-            log.step(f'Starting Docker image {docker_image}...')
-            with DockerContainer(docker_image, simulate_32_bit=platform_tag.endswith('i686'), cwd=container_project_path) as docker:
+            log.step(f"Starting Docker image {docker_image}...")
+            with DockerContainer(
+                docker_image,
+                simulate_32_bit=platform_tag.endswith("i686"),
+                cwd=container_project_path,
+            ) as docker:

-                log.step('Copying project into Docker...')
+                log.step("Copying project into Docker...")
                docker.copy_into(Path.cwd(), container_project_path)

                if options.before_all:
-                    log.step('Running before_all...')
+                    log.step("Running before_all...")

                    env = docker.get_environment()
-                    env['PATH'] = f'/opt/python/cp38-cp38/bin:{env["PATH"]}'
-                    env['PIP_DISABLE_PIP_VERSION_CHECK'] = '1'
-                    env = options.environment.as_dictionary(env, executor=docker.environment_executor)
+                    env["PATH"] = f'/opt/python/cp38-cp38/bin:{env["PATH"]}'
+                    env["PIP_DISABLE_PIP_VERSION_CHECK"] = "1"
+                    env = options.environment.as_dictionary(
+                        env, executor=docker.environment_executor
+                    )

-                    before_all_prepared = prepare_command(options.before_all, project=container_project_path, package=container_package_dir)
-                    docker.call(['sh', '-c', before_all_prepared], env=env)
+                    before_all_prepared = prepare_command(
+                        options.before_all,
+                        project=container_project_path,
+                        package=container_package_dir,
+                    )
+                    docker.call(["sh", "-c", before_all_prepared], env=env)

                for config in platform_configs:
                    log.build_start(config.identifier)

                    dependency_constraint_flags: List[PathOrStr] = []
-                    if config.identifier.startswith("pp"):
-                        # Patch PyPy to make sure headers get installed into a venv
-                        patch_version = '_27' if config.version == '2.7' else ''
-                        patch_path = resources_dir / f'pypy_venv{patch_version}.patch'
-                        patch_docker_path = PurePath('/pypy_venv.patch')
-                        docker.copy_into(patch_path, patch_docker_path)
-                        try:
-                            docker.call(['patch', '--force', '-p1', '-d', config.path, '-i', patch_docker_path])
-                        except subprocess.CalledProcessError:
-                            print("PyPy patch not applied", file=sys.stderr)

                    if options.dependency_constraints:
-                        constraints_file = options.dependency_constraints.get_for_python_version(config.version)
-                        container_constraints_file = PurePath('/constraints.txt')
+                        constraints_file = options.dependency_constraints.get_for_python_version(
+                            config.version
+                        )
+                        container_constraints_file = PurePath("/constraints.txt")

                        docker.copy_into(constraints_file, container_constraints_file)
-                        dependency_constraint_flags = ['-c', container_constraints_file]
+                        dependency_constraint_flags = ["-c", container_constraints_file]

-                    log.step('Setting up build environment...')
+                    log.step("Setting up build environment...")

                    env = docker.get_environment()

                    # put this config's python top of the list
-                    python_bin = config.path / 'bin'
-                    env['PATH'] = f'{python_bin}:{env["PATH"]}'
+                    python_bin = config.path / "bin"
+                    env["PATH"] = f'{python_bin}:{env["PATH"]}'

-                    env = options.environment.as_dictionary(env, executor=docker.environment_executor)
+                    env = options.environment.as_dictionary(
+                        env, executor=docker.environment_executor
+                    )

-                    # check config python and pip are still on PATH
-                    which_python = docker.call(['which', 'python'], env=env, capture_output=True).strip()
-                    if PurePath(which_python) != python_bin / 'python':
-                        print("cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it.", file=sys.stderr)
+                    # check config python is still on PATH
+                    which_python = docker.call(
+                        ["which", "python"], env=env, capture_output=True
+                    ).strip()
+                    if PurePath(which_python) != python_bin / "python":
+                        print(
+                            "cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it.",
+                            file=sys.stderr,
+                        )
                        sys.exit(1)

-                    which_pip = docker.call(['which', 'pip'], env=env, capture_output=True).strip()
-                    if PurePath(which_pip) != python_bin / 'pip':
-                        print("cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.", file=sys.stderr)
+                    which_pip = docker.call(["which", "pip"], env=env, capture_output=True).strip()
+                    if PurePath(which_pip) != python_bin / "pip":
+                        print(
+                            "cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.",
+                            file=sys.stderr,
+                        )
                        sys.exit(1)

                    if options.before_build:
-                        log.step('Running before_build...')
-                        before_build_prepared = prepare_command(options.before_build, project=container_project_path, package=container_package_dir)
-                        docker.call(['sh', '-c', before_build_prepared], env=env)
+                        log.step("Running before_build...")
+                        before_build_prepared = prepare_command(
+                            options.before_build,
+                            project=container_project_path,
+                            package=container_package_dir,
+                        )
+                        docker.call(["sh", "-c", before_build_prepared], env=env)

-                    log.step('Building wheel...')
+                    log.step("Building wheel...")

-                    temp_dir = PurePath('/tmp/cibuildwheel')
-                    built_wheel_dir = temp_dir / 'built_wheel'
-                    docker.call(['rm', '-rf', built_wheel_dir])
-                    docker.call(['mkdir', '-p', built_wheel_dir])
+                    temp_dir = PurePath("/tmp/cibuildwheel")
+                    built_wheel_dir = temp_dir / "built_wheel"
+                    docker.call(["rm", "-rf", built_wheel_dir])
+                    docker.call(["mkdir", "-p", built_wheel_dir])

-                    docker.call([
-                        'pip', 'wheel',
-                        container_package_dir,
-                        '--wheel-dir', built_wheel_dir,
-                        '--no-deps',
-                        *get_build_verbosity_extra_flags(options.build_verbosity)
-                    ], env=env)
+                    verbosity_flags = get_build_verbosity_extra_flags(options.build_verbosity)

-                    built_wheel = docker.glob(built_wheel_dir, '*.whl')[0]
+                    if options.build_frontend == "pip":
+                        docker.call(
+                            [
+                                "python",
+                                "-m",
+                                "pip",
+                                "wheel",
+                                container_package_dir,
+                                f"--wheel-dir={built_wheel_dir}",
+                                "--no-deps",
+                                *verbosity_flags,
+                            ],
+                            env=env,
+                        )
+                    elif options.build_frontend == "build":
+                        config_setting = " ".join(verbosity_flags)
+                        docker.call(
+                            [
+                                "python",
+                                "-m",
+                                "build",
+                                container_package_dir,
+                                "--wheel",
+                                f"--outdir={built_wheel_dir}",
+                                f"--config-setting={config_setting}",
+                            ],
+                            env=env,
+                        )
+                    else:
+                        assert_never(options.build_frontend)

-                    repaired_wheel_dir = temp_dir / 'repaired_wheel'
-                    docker.call(['rm', '-rf', repaired_wheel_dir])
-                    docker.call(['mkdir', '-p', repaired_wheel_dir])
+                    built_wheel = docker.glob(built_wheel_dir, "*.whl")[0]

-                    if built_wheel.name.endswith('none-any.whl'):
+                    repaired_wheel_dir = temp_dir / "repaired_wheel"
+                    docker.call(["rm", "-rf", repaired_wheel_dir])
+                    docker.call(["mkdir", "-p", repaired_wheel_dir])
+
+                    if built_wheel.name.endswith("none-any.whl"):
                        raise NonPlatformWheelError()

                    if options.repair_command:
-                        log.step('Repairing wheel...')
-                        repair_command_prepared = prepare_command(options.repair_command, wheel=built_wheel, dest_dir=repaired_wheel_dir)
-                        docker.call(['sh', '-c', repair_command_prepared], env=env)
+                        log.step("Repairing wheel...")
+                        repair_command_prepared = prepare_command(
+                            options.repair_command, wheel=built_wheel, dest_dir=repaired_wheel_dir
+                        )
+                        docker.call(["sh", "-c", repair_command_prepared], env=env)
                    else:
-                        docker.call(['mv', built_wheel, repaired_wheel_dir])
+                        docker.call(["mv", built_wheel, repaired_wheel_dir])

-                    repaired_wheels = docker.glob(repaired_wheel_dir, '*.whl')
+                    repaired_wheels = docker.glob(repaired_wheel_dir, "*.whl")

                    if options.test_command and options.test_selector(config.identifier):
-                        log.step('Testing wheel...')
+                        log.step("Testing wheel...")

                        # set up a virtual environment to install and test from, to make sure
                        # there are no dependencies that were pulled in at build time.
-                        docker.call(['pip', 'install', 'virtualenv', *dependency_constraint_flags], env=env)
-                        venv_dir = PurePath(docker.call(['mktemp', '-d'], capture_output=True).strip()) / 'venv'
+                        docker.call(
+                            ["pip", "install", "virtualenv", *dependency_constraint_flags], env=env
+                        )
+                        venv_dir = (
+                            PurePath(docker.call(["mktemp", "-d"], capture_output=True).strip())
+                            / "venv"
+                        )

-                        docker.call(['python', '-m', 'virtualenv', '--no-download', venv_dir], env=env)
+                        docker.call(
+                            ["python", "-m", "virtualenv", "--no-download", venv_dir], env=env
+                        )

                        virtualenv_env = env.copy()
-                        virtualenv_env['PATH'] = f"{venv_dir / 'bin'}:{virtualenv_env['PATH']}"
+                        virtualenv_env["PATH"] = f"{venv_dir / 'bin'}:{virtualenv_env['PATH']}"

                        if options.before_test:
-                            before_test_prepared = prepare_command(options.before_test, project=container_project_path, package=container_package_dir)
-                            docker.call(['sh', '-c', before_test_prepared], env=virtualenv_env)
+                            before_test_prepared = prepare_command(
+                                options.before_test,
+                                project=container_project_path,
+                                package=container_package_dir,
+                            )
+                            docker.call(["sh", "-c", before_test_prepared], env=virtualenv_env)

                        # Install the wheel we just built
                        # Note: If auditwheel produced two wheels, it's because the earlier produced wheel
@@ -206,52 +268,73 @@ def build(options: BuildOptions) -> None:
                        # different external shared libraries. so it doesn't matter which one we run the tests on.
                        # Let's just pick the first one.
                        wheel_to_test = repaired_wheels[0]
-                        docker.call(['pip', 'install', str(wheel_to_test) + options.test_extras], env=virtualenv_env)
+                        docker.call(
+                            ["pip", "install", str(wheel_to_test) + options.test_extras],
+                            env=virtualenv_env,
+                        )

                        # Install any requirements to run the tests
                        if options.test_requires:
-                            docker.call(['pip', 'install', *options.test_requires], env=virtualenv_env)
+                            docker.call(
+                                ["pip", "install", *options.test_requires], env=virtualenv_env
+                            )

                        # Run the tests from a different directory
-                        test_command_prepared = prepare_command(options.test_command, project=container_project_path, package=container_package_dir)
-                        docker.call(['sh', '-c', test_command_prepared], cwd='/root', env=virtualenv_env)
+                        test_command_prepared = prepare_command(
+                            options.test_command,
+                            project=container_project_path,
+                            package=container_package_dir,
+                        )
+                        docker.call(
+                            ["sh", "-c", test_command_prepared], cwd="/root", env=virtualenv_env
+                        )

                        # clean up test environment
-                        docker.call(['rm', '-rf', venv_dir])
+                        docker.call(["rm", "-rf", venv_dir])

                    # move repaired wheels to output
-                    docker.call(['mkdir', '-p', container_output_dir])
-                    docker.call(['mv', *repaired_wheels, container_output_dir])
+                    docker.call(["mkdir", "-p", container_output_dir])
+                    docker.call(["mv", *repaired_wheels, container_output_dir])

                    log.build_end()

-                log.step('Copying wheels back to host...')
+                log.step("Copying wheels back to host...")
                # copy the output back into the host
                docker.copy_out(container_output_dir, options.output_dir)
                log.step_end()
        except subprocess.CalledProcessError as error:
-            log.step_end_with_error(f'Command {error.cmd} failed with code {error.returncode}. {error.stdout}')
+            log.step_end_with_error(
+                f"Command {error.cmd} failed with code {error.returncode}. {error.stdout}"
+            )
            troubleshoot(options.package_dir, error)
            sys.exit(1)


 def troubleshoot(package_dir: Path, error: Exception) -> None:
-    if (isinstance(error, subprocess.CalledProcessError) and error.cmd[0:2] == ['pip', 'wheel']):
-        # the 'pip wheel' step failed.
-        print('Checking for common errors...')
-        so_files = list(package_dir.glob('**/*.so'))
+    if isinstance(error, subprocess.CalledProcessError) and (
+        error.cmd[0:4] == ["python", "-m", "pip", "wheel"]
+        or error.cmd[0:3] == ["python", "-m", "build"]
+    ):
+        # the wheel build step failed
+        print("Checking for common errors...")
+        so_files = list(package_dir.glob("**/*.so"))

        if so_files:
-            print(textwrap.dedent('''
-                NOTE: Shared object (.so) files found in this project.
+            print(
+                textwrap.dedent(
+                    """
+                    NOTE: Shared object (.so) files found in this project.

-                  These files might be built against the wrong OS, causing problems with
-                  auditwheel.
+                    These files might be built against the wrong OS, causing problems with
+                    auditwheel.

-                  If you're using Cython and have previously done an in-place build,
-                  remove those build files (*.so and *.c) before starting cibuildwheel.
-            '''), file=sys.stderr)
+                    If you're using Cython and have previously done an in-place build,
+                    remove those build files (*.so and *.c) before starting cibuildwheel.
+                    """
+                ),
+                file=sys.stderr,
+            )

-            print('  Files detected:')
-            print('\n'.join(f'    {f}' for f in so_files))
-            print('')
+            print("  Files detected:")
+            print("\n".join(f"    {f}" for f in so_files))
+            print("")
@@ -7,24 +7,24 @@ from typing import IO, AnyStr, Optional, Union

 from cibuildwheel.util import CIProvider, detect_ci_provider

-DEFAULT_FOLD_PATTERN = ('{name}', '')
+DEFAULT_FOLD_PATTERN = ("{name}", "")
 FOLD_PATTERNS = {
-    'azure': ('##[group]{name}', '##[endgroup]'),
-    'travis': ('travis_fold:start:{identifier}\n{name}', 'travis_fold:end:{identifier}'),
-    'github': ('::group::{name}', '::endgroup::{name}'),
+    "azure": ("##[group]{name}", "##[endgroup]"),
+    "travis": ("travis_fold:start:{identifier}\n{name}", "travis_fold:end:{identifier}"),
+    "github": ("::group::{name}", "::endgroup::{name}"),
 }

 PLATFORM_IDENTIFIER_DESCIPTIONS = {
-    'manylinux_x86_64': 'manylinux x86_64',
-    'manylinux_i686': 'manylinux i686',
-    'manylinux_aarch64': 'manylinux aarch64',
-    'manylinux_ppc64le': 'manylinux ppc64le',
-    'manylinux_s390x': 'manylinux s390x',
-    'win32': 'Windows 32bit',
-    'win_amd64': 'Windows 64bit',
-    'macosx_x86_64': 'macOS x86_64',
-    'macosx_universal2': 'macOS Universal 2 - x86_64 and arm64',
-    'macosx_arm64': 'macOS arm64 - Apple Silicon',
+    "manylinux_x86_64": "manylinux x86_64",
+    "manylinux_i686": "manylinux i686",
+    "manylinux_aarch64": "manylinux aarch64",
+    "manylinux_ppc64le": "manylinux ppc64le",
+    "manylinux_s390x": "manylinux s390x",
+    "win32": "Windows 32bit",
+    "win_amd64": "Windows 64bit",
+    "macosx_x86_64": "macOS x86_64",
+    "macosx_universal2": "macOS Universal 2 - x86_64 and arm64",
+    "macosx_arm64": "macOS arm64 - Apple Silicon",
 }


@@ -38,33 +38,33 @@ class Logger:
    active_fold_group_name: Optional[str] = None

    def __init__(self) -> None:
-        if sys.platform == 'win32' and hasattr(sys.stdout, 'reconfigure'):
+        if sys.platform == "win32" and hasattr(sys.stdout, "reconfigure"):
            # the encoding on Windows can be a 1-byte charmap, but all CIs
            # support utf8, so we hardcode that
-            sys.stdout.reconfigure(encoding='utf8')
+            sys.stdout.reconfigure(encoding="utf8")

        self.unicode_enabled = file_supports_unicode(sys.stdout)

        ci_provider = detect_ci_provider()

        if ci_provider == CIProvider.azure_pipelines:
-            self.fold_mode = 'azure'
+            self.fold_mode = "azure"
            self.colors_enabled = True

        elif ci_provider == CIProvider.github_actions:
-            self.fold_mode = 'github'
+            self.fold_mode = "github"
            self.colors_enabled = True

        elif ci_provider == CIProvider.travis_ci:
-            self.fold_mode = 'travis'
+            self.fold_mode = "travis"
            self.colors_enabled = True

        elif ci_provider == CIProvider.appveyor:
-            self.fold_mode = 'disabled'
+            self.fold_mode = "disabled"
            self.colors_enabled = True

        else:
-            self.fold_mode = 'disabled'
+            self.fold_mode = "disabled"
            self.colors_enabled = file_supports_color(sys.stdout)

    def build_start(self, identifier: str) -> None:
@@ -72,8 +72,8 @@ class Logger:
        c = self.colors
        description = build_description_from_identifier(identifier)
        print()
-        print(f'{c.bold}{c.blue}Building {identifier} wheel{c.end}')
-        print(f'{description}')
+        print(f"{c.bold}{c.blue}Building {identifier} wheel{c.end}")
+        print(f"{description}")
        print()

        self.build_start_time = time.time()
@@ -89,7 +89,9 @@ class Logger:
        duration = time.time() - self.build_start_time

        print()
-        print(f'{c.green}{s.done} {c.end}{self.active_build_identifier} finished in {duration:.2f}s')
+        print(
+            f"{c.green}{s.done} {c.end}{self.active_build_identifier} finished in {duration:.2f}s"
+        )
        self.build_start_time = None
        self.active_build_identifier = None

@@ -105,9 +107,9 @@ class Logger:
            s = self.symbols
            duration = time.time() - self.step_start_time
            if success:
-                print(f'{c.green}{s.done} {c.end}{duration:.2f}s'.rjust(78))
+                print(f"{c.green}{s.done} {c.end}{duration:.2f}s".rjust(78))
            else:
-                print(f'{c.red}{s.error} {c.end}{duration:.2f}s'.rjust(78))
+                print(f"{c.red}{s.error} {c.end}{duration:.2f}s".rjust(78))

            self.step_start_time = None

@@ -116,18 +118,18 @@ class Logger:
        self.error(error)

    def warning(self, message: str) -> None:
-        if self.fold_mode == 'github':
-            print(f'::warning::{message}\n', file=sys.stderr)
+        if self.fold_mode == "github":
+            print(f"::warning::{message}\n", file=sys.stderr)
        else:
            c = self.colors
-            print(f'{c.yellow}Warning{c.end}: {message}\n', file=sys.stderr)
+            print(f"{c.yellow}Warning{c.end}: {message}\n", file=sys.stderr)

    def error(self, error: Union[BaseException, str]) -> None:
-        if self.fold_mode == 'github':
-            print(f'::error::{error}\n', file=sys.stderr)
+        if self.fold_mode == "github":
+            print(f"::error::{error}\n", file=sys.stderr)
        else:
            c = self.colors
-            print(f'{c.bright_red}Error{c.end}: {error}\n', file=sys.stderr)
+            print(f"{c.bright_red}Error{c.end}: {error}\n", file=sys.stderr)

    def _start_fold_group(self, name: str) -> None:
        self._end_fold_group()
@@ -143,21 +145,23 @@ class Logger:
        if self.active_fold_group_name:
            fold_start_pattern = FOLD_PATTERNS.get(self.fold_mode, DEFAULT_FOLD_PATTERN)[1]
            identifier = self._fold_group_identifier(self.active_fold_group_name)
-            print(fold_start_pattern.format(name=self.active_fold_group_name, identifier=identifier))
+            print(
+                fold_start_pattern.format(name=self.active_fold_group_name, identifier=identifier)
+            )
            sys.stdout.flush()
            self.active_fold_group_name = None

    def _fold_group_identifier(self, name: str) -> str:
-        '''
+        """
        Travis doesn't like fold groups identifiers that have spaces in. This
        method converts them to ascii identifiers
-        '''
+        """
        # whitespace to underscores
-        identifier = re.sub(r'\s+', '_', name)
+        identifier = re.sub(r"\s+", "_", name)
        # remove non-alphanum
-        identifier = re.sub(r'[^A-Za-z\d_]+', '', identifier)
+        identifier = re.sub(r"[^A-Za-z\d_]+", "", identifier)
        # trim underscores
-        identifier = identifier.strip('_')
+        identifier = identifier.strip("_")
        # lowercase, shorten
        return identifier.lower()[:20]

@@ -177,53 +181,53 @@ class Logger:


 def build_description_from_identifier(identifier: str) -> str:
-    python_identifier, _, platform_identifier = identifier.partition('-')
+    python_identifier, _, platform_identifier = identifier.partition("-")

-    build_description = ''
+    build_description = ""

    python_interpreter = python_identifier[0:2]
-    python_version = python_identifier[2:4]
+    python_version = python_identifier[2:]

-    if python_interpreter == 'cp':
-        build_description += 'CPython'
-    elif python_interpreter == 'pp':
-        build_description += 'PyPy'
+    if python_interpreter == "cp":
+        build_description += "CPython"
+    elif python_interpreter == "pp":
+        build_description += "PyPy"
    else:
-        raise Exception('unknown python')
+        raise Exception("unknown python")

-    build_description += f' {python_version[0]}.{python_version[1]} '
+    build_description += f" {python_version[0]}.{python_version[1:]} "

    try:
        build_description += PLATFORM_IDENTIFIER_DESCIPTIONS[platform_identifier]
    except KeyError as e:
-        raise Exception('unknown platform') from e
+        raise Exception("unknown platform") from e

    return build_description


 class Colors:
    def __init__(self, *, enabled: bool) -> None:
-        self.red = '\033[31m' if enabled else ''
-        self.green = '\033[32m' if enabled else ''
-        self.yellow = '\033[33m' if enabled else ''
-        self.blue = '\033[34m' if enabled else ''
-        self.cyan = '\033[36m' if enabled else ''
-        self.bright_red = '\033[91m' if enabled else ''
-        self.bright_green = '\033[92m' if enabled else ''
-        self.white = '\033[37m\033[97m' if enabled else ''
+        self.red = "\033[31m" if enabled else ""
+        self.green = "\033[32m" if enabled else ""
+        self.yellow = "\033[33m" if enabled else ""
+        self.blue = "\033[34m" if enabled else ""
+        self.cyan = "\033[36m" if enabled else ""
+        self.bright_red = "\033[91m" if enabled else ""
+        self.bright_green = "\033[92m" if enabled else ""
+        self.white = "\033[37m\033[97m" if enabled else ""

-        self.bg_grey = '\033[48;5;235m' if enabled else ''
+        self.bg_grey = "\033[48;5;235m" if enabled else ""

-        self.bold = '\033[1m' if enabled else ''
-        self.faint = '\033[2m' if enabled else ''
+        self.bold = "\033[1m" if enabled else ""
+        self.faint = "\033[2m" if enabled else ""

-        self.end = '\033[0m' if enabled else ''
+        self.end = "\033[0m" if enabled else ""


 class Symbols:
    def __init__(self, *, unicode: bool) -> None:
-        self.done = '✓' if unicode else 'done'
-        self.error = '✕' if unicode else 'failed'
+        self.done = "✓" if unicode else "done"
+        self.error = "✕" if unicode else "failed"


 def file_supports_color(file_obj: IO[AnyStr]) -> bool:
@@ -231,29 +235,29 @@ def file_supports_color(file_obj: IO[AnyStr]) -> bool:
    Returns True if the running system's terminal supports color.
    """
    plat = sys.platform
-    supported_platform = (plat != 'win32' or 'ANSICON' in os.environ)
+    supported_platform = plat != "win32" or "ANSICON" in os.environ

    is_a_tty = file_is_a_tty(file_obj)

-    return (supported_platform and is_a_tty)
+    return supported_platform and is_a_tty


 def file_is_a_tty(file_obj: IO[AnyStr]) -> bool:
-    return hasattr(file_obj, 'isatty') and file_obj.isatty()
+    return hasattr(file_obj, "isatty") and file_obj.isatty()


 def file_supports_unicode(file_obj: IO[AnyStr]) -> bool:
-    encoding = getattr(file_obj, 'encoding', None)
+    encoding = getattr(file_obj, "encoding", None)
    if not encoding:
        return False

    codec_info = codecs.lookup(encoding)

-    return ('utf' in codec_info.name)
+    return "utf" in codec_info.name


-'''
+"""
 Global instance of the Logger.
-'''
+"""
 # (there's only one stdout per-process, so a global instance is justified)
 log = Logger()
@@ -12,41 +12,46 @@ from typing import Any, Dict, List, NamedTuple, Optional, Sequence, Set, Tuple,
 from .architecture import Architecture
 from .environment import ParsedEnvironment
 from .logger import log
-from .typing import Literal, PathOrStr
+from .typing import Literal, PathOrStr, assert_never
 from .util import (
+    BuildFrontend,
    BuildOptions,
    BuildSelector,
    NonPlatformWheelError,
    download,
    get_build_verbosity_extra_flags,
-    get_pip_script,
+    get_pip_version,
    install_certifi_script,
    prepare_command,
    read_python_configs,
-    resources_dir,
    unwrap,
 )


-def call(args: Sequence[PathOrStr], env: Optional[Dict[str, str]] = None, cwd: Optional[str] = None, shell: bool = False) -> None:
+def call(
+    args: Sequence[PathOrStr],
+    env: Optional[Dict[str, str]] = None,
+    cwd: Optional[str] = None,
+    shell: bool = False,
+) -> None:
    # print the command executing for the logs
    if shell:
-        print(f'+ {args}')
+        print(f"+ {args}")
    else:
-        print('+ ' + ' '.join(shlex.quote(str(a)) for a in args))
+        print("+ " + " ".join(shlex.quote(str(a)) for a in args))

    subprocess.run(args, env=env, cwd=cwd, shell=shell, check=True)


 def get_macos_version() -> Tuple[int, int]:
-    '''
+    """
    Returns the macOS major/minor version, as a tuple, e.g. (10, 15) or (11, 0)

    These tuples can be used in comparisons, e.g.
        (10, 14) <= (11, 0) == True
        (10, 14) <= (10, 16) == True
        (11, 2) <= (11, 0) != True
-    '''
+    """
    version_str, _, _ = platform.mac_ver()
    version = tuple(map(int, version_str.split(".")[:2]))
    return cast(Tuple[int, int], version)
@@ -54,13 +59,13 @@ def get_macos_version() -> Tuple[int, int]:

 def get_macos_sdks() -> List[str]:
    output = subprocess.run(
-        ['xcodebuild', '-showsdks'],
+        ["xcodebuild", "-showsdks"],
        universal_newlines=True,
        check=True,
        stdout=subprocess.PIPE,
    ).stdout

-    return [m.group(1) for m in re.finditer(r'-sdk (macosx\S+)', output)]
+    return [m.group(1) for m in re.finditer(r"-sdk (macosx\S+)", output)]


 class PythonConfiguration(NamedTuple):
@@ -69,16 +74,20 @@ class PythonConfiguration(NamedTuple):
    url: str


-def get_python_configurations(build_selector: BuildSelector,
-                              architectures: Set[Architecture]) -> List[PythonConfiguration]:
+def get_python_configurations(
+    build_selector: BuildSelector, architectures: Set[Architecture]
+) -> List[PythonConfiguration]:

-    full_python_configs = read_python_configs('macos')
+    full_python_configs = read_python_configs("macos")

    python_configurations = [PythonConfiguration(**item) for item in full_python_configs]

    # filter out configs that don't match any of the selected architectures
-    python_configurations = [c for c in python_configurations
-                             if any(c.identifier.endswith(a.value) for a in architectures)]
+    python_configurations = [
+        c
+        for c in python_configurations
+        if any(c.identifier.endswith(a.value) for a in architectures)
+    ]

    # skip builds as required by BUILD/SKIP
    python_configurations = [c for c in python_configurations if build_selector(c.identifier)]
@@ -86,29 +95,26 @@ def get_python_configurations(build_selector: BuildSelector,
    # When running on macOS 11 and x86_64, the reported OS is '10.16', but
    # there is no such OS - it really means macOS 11.
    if get_macos_version() >= (10, 16):
-        if any(c.identifier.startswith('pp') for c in python_configurations):
+        if any(c.identifier.startswith("pp") for c in python_configurations):
            # pypy doesn't work on macOS 11 yet
            # See https://foss.heptapod.net/pypy/pypy/-/issues/3314
-            log.warning(unwrap('''
-                PyPy is currently unsupported when building on macOS 11. To build macOS PyPy wheels,
-                build on an older OS, such as macOS 10.15. To silence this warning, deselect PyPy by
-                adding "pp*-macosx*" to your CIBW_SKIP option.
-            '''))
-            python_configurations = [c for c in python_configurations if not c.identifier.startswith('pp')]
-
-        if any(c.identifier.startswith('cp35') for c in python_configurations):
-            # CPython 3.5 doesn't work on macOS 11
-            log.warning(unwrap('''
-                CPython 3.5 is unsupported when building on macOS 11. To build CPython 3.5 wheels,
-                build on an older OS, such as macOS 10.15. To silence this warning, deselect CPython
-                3.5 by adding "cp35-macosx_x86_64" to your CIBW_SKIP option.
-            '''))
-            python_configurations = [c for c in python_configurations if not c.identifier.startswith('cp35')]
+            log.warning(
+                unwrap(
+                    """
+                    PyPy is currently unsupported when building on macOS 11. To build macOS PyPy
+                    wheels, build on an older OS, such as macOS 10.15. To silence this warning,
+                    deselect PyPy by adding "pp*-macosx*" to your CIBW_SKIP option.
+                    """
+                )
+            )
+            python_configurations = [
+                c for c in python_configurations if not c.identifier.startswith("pp")
+            ]

    return python_configurations


-SYMLINKS_DIR = Path('/tmp/cibw_bin')
+SYMLINKS_DIR = Path("/tmp/cibw_bin")


 def make_symlinks(installation_bin_path: Path, python_executable: str, pip_executable: str) -> None:
@@ -121,82 +127,84 @@ def make_symlinks(installation_bin_path: Path, python_executable: str, pip_execu
        shutil.rmtree(SYMLINKS_DIR)
    SYMLINKS_DIR.mkdir(parents=True)

-    (SYMLINKS_DIR / 'python').symlink_to(installation_bin_path / python_executable)
-    (SYMLINKS_DIR / 'python-config').symlink_to(installation_bin_path / (python_executable + '-config'))
-    (SYMLINKS_DIR / 'pip').symlink_to(installation_bin_path / pip_executable)
+    (SYMLINKS_DIR / "python").symlink_to(installation_bin_path / python_executable)
+    (SYMLINKS_DIR / "python-config").symlink_to(
+        installation_bin_path / (python_executable + "-config")
+    )
+    (SYMLINKS_DIR / "pip").symlink_to(installation_bin_path / pip_executable)


 def install_cpython(version: str, url: str) -> Path:
-    installed_system_packages = subprocess.run(['pkgutil', '--pkgs'], universal_newlines=True, check=True, stdout=subprocess.PIPE).stdout.splitlines()
+    installed_system_packages = subprocess.run(
+        ["pkgutil", "--pkgs"], universal_newlines=True, check=True, stdout=subprocess.PIPE
+    ).stdout.splitlines()

    # if this version of python isn't installed, get it from python.org and install
-    python_package_identifier = f'org.python.Python.PythonFramework-{version}'
-    python_executable = 'python3' if version[0] == '3' else 'python'
-    installation_bin_path = Path(f'/Library/Frameworks/Python.framework/Versions/{version}/bin')
+    python_package_identifier = f"org.python.Python.PythonFramework-{version}"
+    python_executable = "python3"
+    installation_bin_path = Path(f"/Library/Frameworks/Python.framework/Versions/{version}/bin")

    if python_package_identifier not in installed_system_packages:
        # download the pkg
-        download(url, Path('/tmp/Python.pkg'))
+        download(url, Path("/tmp/Python.pkg"))
        # install
-        call(['sudo', 'installer', '-pkg', '/tmp/Python.pkg', '-target', '/'])
-        # patch open ssl
-        if version == '3.5':
-            open_ssl_patch_url = f'https://github.com/mayeut/patch-macos-python-openssl/releases/download/v1.1.1h/patch-macos-python-{version}-openssl-v1.1.1h.tar.gz'
-            download(open_ssl_patch_url, Path('/tmp/python-patch.tar.gz'))
-            call(['sudo', 'tar', '-C', f'/Library/Frameworks/Python.framework/Versions/{version}/', '-xmf', '/tmp/python-patch.tar.gz'])
+        call(["sudo", "installer", "-pkg", "/tmp/Python.pkg", "-target", "/"])
+        call(["sudo", str(installation_bin_path / python_executable), str(install_certifi_script)])

-        call(["sudo", str(installation_bin_path/python_executable), str(install_certifi_script)])
-
-    pip_executable = 'pip3' if version[0] == '3' else 'pip'
+    pip_executable = "pip3"
    make_symlinks(installation_bin_path, python_executable, pip_executable)

    return installation_bin_path


 def install_pypy(version: str, url: str) -> Path:
-    pypy_tar_bz2 = url.rsplit('/', 1)[-1]
+    pypy_tar_bz2 = url.rsplit("/", 1)[-1]
    extension = ".tar.bz2"
    assert pypy_tar_bz2.endswith(extension)
-    pypy_base_filename = pypy_tar_bz2[:-len(extension)]
-    installation_path = Path('/tmp') / pypy_base_filename
+    pypy_base_filename = pypy_tar_bz2[: -len(extension)]
+    installation_path = Path("/tmp") / pypy_base_filename
    if not installation_path.exists():
        downloaded_tar_bz2 = Path("/tmp") / pypy_tar_bz2
        download(url, downloaded_tar_bz2)
-        call(['tar', '-C', '/tmp', '-xf', downloaded_tar_bz2])
-        # Patch PyPy to make sure headers get installed into a venv
-        patch_version = '_27' if version == '2.7' else ''
-        patch_path = resources_dir / f'pypy_venv{patch_version}.patch'
-        call(['patch', '--force', '-p1', '-d', installation_path, '-i', patch_path])
+        call(["tar", "-C", "/tmp", "-xf", downloaded_tar_bz2])

-    installation_bin_path = installation_path / 'bin'
-    python_executable = 'pypy3' if version[0] == '3' else 'pypy'
-    pip_executable = 'pip3' if version[0] == '3' else 'pip'
+    installation_bin_path = installation_path / "bin"
+    python_executable = "pypy3"
+    pip_executable = "pip3"
    make_symlinks(installation_bin_path, python_executable, pip_executable)

    return installation_bin_path


-def setup_python(python_configuration: PythonConfiguration,
-                 dependency_constraint_flags: Sequence[PathOrStr],
-                 environment: ParsedEnvironment) -> Dict[str, str]:
-    implementation_id = python_configuration.identifier.split("-")[0]
-    log.step(f'Installing Python {implementation_id}...')
+def setup_python(
+    python_configuration: PythonConfiguration,
+    dependency_constraint_flags: Sequence[PathOrStr],
+    environment: ParsedEnvironment,
+    build_frontend: BuildFrontend,
+) -> Dict[str, str]:

-    if implementation_id.startswith('cp'):
-        installation_bin_path = install_cpython(python_configuration.version, python_configuration.url)
-    elif implementation_id.startswith('pp'):
+    implementation_id = python_configuration.identifier.split("-")[0]
+    log.step(f"Installing Python {implementation_id}...")
+
+    if implementation_id.startswith("cp"):
+        installation_bin_path = install_cpython(
+            python_configuration.version, python_configuration.url
+        )
+    elif implementation_id.startswith("pp"):
        installation_bin_path = install_pypy(python_configuration.version, python_configuration.url)
    else:
        raise ValueError("Unknown Python implementation")

-    log.step('Setting up build environment...')
+    log.step("Setting up build environment...")

    env = os.environ.copy()
-    env['PATH'] = os.pathsep.join([
-        str(SYMLINKS_DIR),
-        str(installation_bin_path),
-        env['PATH'],
-    ])
+    env["PATH"] = os.pathsep.join(
+        [
+            str(SYMLINKS_DIR),
+            str(installation_bin_path),
+            env["PATH"],
+        ]
+    )

    # Fix issue with site.py setting the wrong `sys.prefix`, `sys.exec_prefix`,
    # `sys.path`, ... for PyPy: https://foss.heptapod.net/pypy/pypy/issues/3175
@@ -204,153 +212,246 @@ def setup_python(python_configuration: PythonConfiguration,
    # testing virtualenv- see https://github.com/theacodes/nox/issues/44 and
    # https://github.com/pypa/virtualenv/issues/620
    # Also see https://github.com/python/cpython/pull/9516
-    env.pop('__PYVENV_LAUNCHER__', None)
+    env.pop("__PYVENV_LAUNCHER__", None)
    env = environment.as_dictionary(prev_environment=env)

    # we version pip ourselves, so we don't care about pip version checking
-    env['PIP_DISABLE_PIP_VERSION_CHECK'] = '1'
+    env["PIP_DISABLE_PIP_VERSION_CHECK"] = "1"

    # check what version we're on
-    call(['which', 'python'], env=env)
-    call(['python', '--version'], env=env)
-    which_python = subprocess.run(['which', 'python'], env=env, universal_newlines=True, check=True, stdout=subprocess.PIPE).stdout.strip()
-    if which_python != '/tmp/cibw_bin/python':
-        print("cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it.", file=sys.stderr)
+    call(["which", "python"], env=env)
+    call(["python", "--version"], env=env)
+    which_python = subprocess.run(
+        ["which", "python"], env=env, universal_newlines=True, check=True, stdout=subprocess.PIPE
+    ).stdout.strip()
+    if which_python != "/tmp/cibw_bin/python":
+        print(
+            "cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it.",
+            file=sys.stderr,
+        )
        sys.exit(1)

-    # install pip & wheel
-    call(['python', get_pip_script, *dependency_constraint_flags], env=env, cwd="/tmp")
-    assert (installation_bin_path / 'pip').exists()
-    call(['which', 'pip'], env=env)
-    call(['pip', '--version'], env=env)
-    which_pip = subprocess.run(['which', 'pip'], env=env, universal_newlines=True, check=True, stdout=subprocess.PIPE).stdout.strip()
-    if which_pip != '/tmp/cibw_bin/pip':
-        print("cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.", file=sys.stderr)
+    # Install pip
+
+    requires_reinstall = not (installation_bin_path / "pip").exists()
+    if requires_reinstall:
+        # maybe pip isn't installed at all. ensurepip resolves that.
+        call(["python", "-m", "ensurepip"], env=env, cwd="/tmp")
+
+    # upgrade pip to the version matching our constraints
+    # if necessary, reinstall it to ensure that it's available on PATH as 'pip'
+    call(
+        [
+            "python",
+            "-m",
+            "pip",
+            "install",
+            "--force-reinstall" if requires_reinstall else "--upgrade",
+            "pip",
+            *dependency_constraint_flags,
+        ],
+        env=env,
+        cwd="/tmp",
+    )
+
+    assert (installation_bin_path / "pip").exists()
+    call(["which", "pip"], env=env)
+    call(["pip", "--version"], env=env)
+    which_pip = subprocess.run(
+        ["which", "pip"], env=env, universal_newlines=True, check=True, stdout=subprocess.PIPE
+    ).stdout.strip()
+    if which_pip != "/tmp/cibw_bin/pip":
+        print(
+            "cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.",
+            file=sys.stderr,
+        )
        sys.exit(1)

    # Set MACOSX_DEPLOYMENT_TARGET to 10.9, if the user didn't set it.
-    # CPython 3.5 defaults to 10.6, and pypy defaults to 10.7, causing
-    # inconsistencies if it's left unset.
-    env.setdefault('MACOSX_DEPLOYMENT_TARGET', '10.9')
+    # PyPy defaults to 10.7, causing inconsistencies if it's left unset.
+    env.setdefault("MACOSX_DEPLOYMENT_TARGET", "10.9")

-    config_is_arm64 = python_configuration.identifier.endswith('arm64')
-    config_is_universal2 = python_configuration.identifier.endswith('universal2')
+    config_is_arm64 = python_configuration.identifier.endswith("arm64")
+    config_is_universal2 = python_configuration.identifier.endswith("universal2")

-    if python_configuration.version == '3.5':
-        # Cross-compilation platform override - CPython 3.5 has an
-        # i386/x86_64 version of Python, but we only want a x64_64 build
-        env.setdefault('_PYTHON_HOST_PLATFORM', 'macosx-10.9-x86_64')
-        # https://github.com/python/cpython/blob/a5ed2fe0eedefa1649aa93ee74a0bafc8e628a10/Lib/_osx_support.py#L260
-        env.setdefault('ARCHFLAGS', '-arch x86_64')
-
-    if python_configuration.version == '3.9':
-        if python_configuration.identifier.endswith('x86_64'):
-            # even on the macos11.0 Python installer, on the x86_64 side it's
-            # compatible back to 10.9.
-            env.setdefault('_PYTHON_HOST_PLATFORM', 'macosx-10.9-x86_64')
-            env.setdefault('ARCHFLAGS', '-arch x86_64')
-        elif config_is_arm64:
+    if python_configuration.version not in {"3.6", "3.7"}:
+        if config_is_arm64:
            # macOS 11 is the first OS with arm64 support, so the wheels
            # have that as a minimum.
-            env.setdefault('_PYTHON_HOST_PLATFORM', 'macosx-11.0-arm64')
-            env.setdefault('ARCHFLAGS', '-arch arm64')
+            env.setdefault("_PYTHON_HOST_PLATFORM", "macosx-11.0-arm64")
+            env.setdefault("ARCHFLAGS", "-arch arm64")
        elif config_is_universal2:
-            if get_macos_version() < (10, 16):
-                # we can do universal2 builds on macos 10.15, but we need to
-                # set ARCHFLAGS otherwise CPython sets it to `-arch x86_64`
-                env.setdefault('ARCHFLAGS', '-arch arm64 -arch x86_64')
+            env.setdefault("_PYTHON_HOST_PLATFORM", "macosx-10.9-universal2")
+            env.setdefault("ARCHFLAGS", "-arch arm64 -arch x86_64")
+        elif python_configuration.identifier.endswith("x86_64"):
+            # even on the macos11.0 Python installer, on the x86_64 side it's
+            # compatible back to 10.9.
+            env.setdefault("_PYTHON_HOST_PLATFORM", "macosx-10.9-x86_64")
+            env.setdefault("ARCHFLAGS", "-arch x86_64")

    building_arm64 = config_is_arm64 or config_is_universal2
-    if building_arm64 and get_macos_version() < (10, 16) and 'SDKROOT' not in env:
+    if building_arm64 and get_macos_version() < (10, 16) and "SDKROOT" not in env:
        # xcode 12.2 or higher can build arm64 on macos 10.15 or below, but
        # needs the correct SDK selected.
        sdks = get_macos_sdks()

        # Different versions of Xcode contain different SDK versions...
        # we're happy with anything newer than macOS 11.0
-        arm64_compatible_sdks = [s for s in sdks if not s.startswith('macosx10.')]
+        arm64_compatible_sdks = [s for s in sdks if not s.startswith("macosx10.")]

        if not arm64_compatible_sdks:
-            log.warning(unwrap('''
+            log.warning(
+                unwrap(
+                    """
                    SDK for building arm64-compatible wheels not found. You need Xcode 12.2 or later
                    to build universal2 or arm64 wheels.
-                '''))
+                    """
+                )
+            )
        else:
-            env.setdefault('SDKROOT', arm64_compatible_sdks[0])
+            env.setdefault("SDKROOT", arm64_compatible_sdks[0])

-    log.step('Installing build tools...')
-    call(['pip', 'install', '--upgrade', 'setuptools', 'wheel', 'delocate', *dependency_constraint_flags], env=env)
+    log.step("Installing build tools...")
+    if build_frontend == "pip":
+        call(
+            [
+                "pip",
+                "install",
+                "--upgrade",
+                "setuptools",
+                "wheel",
+                "delocate",
+                *dependency_constraint_flags,
+            ],
+            env=env,
+        )
+    elif build_frontend == "build":
+        call(
+            [
+                "pip",
+                "install",
+                "--upgrade",
+                "delocate",
+                "build[virtualenv]",
+                *dependency_constraint_flags,
+            ],
+            env=env,
+        )
+    else:
+        assert_never(build_frontend)

    return env


 def build(options: BuildOptions) -> None:
-    temp_dir = Path(tempfile.mkdtemp(prefix='cibuildwheel'))
-    built_wheel_dir = temp_dir / 'built_wheel'
-    repaired_wheel_dir = temp_dir / 'repaired_wheel'
+    temp_dir = Path(tempfile.mkdtemp(prefix="cibuildwheel"))
+    built_wheel_dir = temp_dir / "built_wheel"
+    repaired_wheel_dir = temp_dir / "repaired_wheel"

    try:
        if options.before_all:
-            log.step('Running before_all...')
+            log.step("Running before_all...")
            env = options.environment.as_dictionary(prev_environment=os.environ)
-            env.setdefault('MACOSX_DEPLOYMENT_TARGET', '10.9')
-            before_all_prepared = prepare_command(options.before_all, project='.', package=options.package_dir)
+            env.setdefault("MACOSX_DEPLOYMENT_TARGET", "10.9")
+            before_all_prepared = prepare_command(
+                options.before_all, project=".", package=options.package_dir
+            )
            call([before_all_prepared], shell=True, env=env)

-        python_configurations = get_python_configurations(options.build_selector, options.architectures)
+        python_configurations = get_python_configurations(
+            options.build_selector, options.architectures
+        )

        for config in python_configurations:
            log.build_start(config.identifier)

-            config_is_arm64 = config.identifier.endswith('arm64')
-            config_is_universal2 = config.identifier.endswith('universal2')
+            config_is_arm64 = config.identifier.endswith("arm64")
+            config_is_universal2 = config.identifier.endswith("universal2")

            dependency_constraint_flags: Sequence[PathOrStr] = []
            if options.dependency_constraints:
                dependency_constraint_flags = [
-                    '-c', options.dependency_constraints.get_for_python_version(config.version)
+                    "-c",
+                    options.dependency_constraints.get_for_python_version(config.version),
                ]

-            env = setup_python(config, dependency_constraint_flags, options.environment)
+            env = setup_python(
+                config,
+                dependency_constraint_flags,
+                options.environment,
+                options.build_frontend,
+            )

            if options.before_build:
-                log.step('Running before_build...')
-                before_build_prepared = prepare_command(options.before_build, project='.', package=options.package_dir)
+                log.step("Running before_build...")
+                before_build_prepared = prepare_command(
+                    options.before_build, project=".", package=options.package_dir
+                )
                call(before_build_prepared, env=env, shell=True)

-            log.step('Building wheel...')
+            log.step("Building wheel...")
            if built_wheel_dir.exists():
                shutil.rmtree(built_wheel_dir)
            built_wheel_dir.mkdir(parents=True)

-            # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
-            # see https://github.com/joerick/cibuildwheel/pull/369
-            call([
-                'pip', 'wheel',
-                options.package_dir.resolve(),
-                '--wheel-dir', built_wheel_dir,
-                '--no-deps',
-                *get_build_verbosity_extra_flags(options.build_verbosity)
-            ], env=env)
+            verbosity_flags = get_build_verbosity_extra_flags(options.build_verbosity)

-            built_wheel = next(built_wheel_dir.glob('*.whl'))
+            if options.build_frontend == "pip":
+                # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
+                # see https://github.com/pypa/cibuildwheel/pull/369
+                call(
+                    [
+                        "python",
+                        "-m",
+                        "pip",
+                        "wheel",
+                        options.package_dir.resolve(),
+                        f"--wheel-dir={built_wheel_dir}",
+                        "--no-deps",
+                        *verbosity_flags,
+                    ],
+                    env=env,
+                )
+            elif options.build_frontend == "build":
+                config_setting = " ".join(verbosity_flags)
+                build_env = env.copy()
+                if options.dependency_constraints:
+                    constr = options.dependency_constraints.get_for_python_version(config.version)
+                    build_env["PIP_CONSTRAINT"] = constr.as_uri()
+                build_env["VIRTUALENV_PIP"] = get_pip_version(env)
+                call(
+                    [
+                        "python",
+                        "-m",
+                        "build",
+                        options.package_dir,
+                        "--wheel",
+                        f"--outdir={built_wheel_dir}",
+                        f"--config-setting={config_setting}",
+                    ],
+                    env=build_env,
+                )
+            else:
+                assert_never(options.build_frontend)
+
+            built_wheel = next(built_wheel_dir.glob("*.whl"))

            if repaired_wheel_dir.exists():
                shutil.rmtree(repaired_wheel_dir)
            repaired_wheel_dir.mkdir(parents=True)

-            if built_wheel.name.endswith('none-any.whl'):
+            if built_wheel.name.endswith("none-any.whl"):
                raise NonPlatformWheelError()

            if options.repair_command:
-                log.step('Repairing wheel...')
+                log.step("Repairing wheel...")

                if config_is_universal2:
-                    delocate_archs = 'x86_64,arm64'
+                    delocate_archs = "x86_64,arm64"
                elif config_is_arm64:
-                    delocate_archs = 'arm64'
+                    delocate_archs = "arm64"
                else:
-                    delocate_archs = 'x86_64'
+                    delocate_archs = "x86_64"

                repair_command_prepared = prepare_command(
                    options.repair_command,
@@ -362,105 +463,137 @@ def build(options: BuildOptions) -> None:
            else:
                shutil.move(str(built_wheel), repaired_wheel_dir)

-            repaired_wheel = next(repaired_wheel_dir.glob('*.whl'))
+            repaired_wheel = next(repaired_wheel_dir.glob("*.whl"))

            log.step_end()

            if options.test_command and options.test_selector(config.identifier):
                machine_arch = platform.machine()
-                testing_archs: List[Literal['x86_64', 'arm64']] = []
+                testing_archs: List[Literal["x86_64", "arm64"]] = []

                if config_is_arm64:
-                    testing_archs = ['arm64']
+                    testing_archs = ["arm64"]
                elif config_is_universal2:
-                    testing_archs = ['x86_64', 'arm64']
+                    testing_archs = ["x86_64", "arm64"]
                else:
-                    testing_archs = ['x86_64']
+                    testing_archs = ["x86_64"]

                for testing_arch in testing_archs:
                    if config_is_universal2:
-                        arch_specific_identifier = f'{config.identifier}:{testing_arch}'
+                        arch_specific_identifier = f"{config.identifier}:{testing_arch}"
                        if not options.test_selector(arch_specific_identifier):
                            continue

-                    if machine_arch == 'x86_64' and testing_arch == 'arm64':
+                    if machine_arch == "x86_64" and testing_arch == "arm64":
                        if config_is_arm64:
-                            log.warning(unwrap('''
-                                While arm64 wheels can be built on x86_64, they cannot be tested. The
-                                ability to test the arm64 wheels will be added in a future release of
-                                cibuildwheel, once Apple Silicon CI runners are widely available. To
-                                silence this warning, set `CIBW_TEST_SKIP: *-macosx_arm64`.
-                            '''))
+                            log.warning(
+                                unwrap(
+                                    """
+                                    While arm64 wheels can be built on x86_64, they cannot be
+                                    tested. The ability to test the arm64 wheels will be added in a
+                                    future release of cibuildwheel, once Apple Silicon CI runners
+                                    are widely available. To silence this warning, set
+                                    `CIBW_TEST_SKIP: *-macosx_arm64`.
+                                    """
+                                )
+                            )
                        elif config_is_universal2:
-                            log.warning(unwrap('''
-                                While universal2 wheels can be built on x86_64, the arm64 part of them
-                                cannot currently be tested. The ability to test the arm64 part of a
-                                universal2 wheel will be added in a future release of cibuildwheel, once
-                                Apple Silicon CI runners are widely available. To silence this warning,
-                                set `CIBW_TEST_SKIP: *-macosx_universal2:arm64`.
-                            '''))
+                            log.warning(
+                                unwrap(
+                                    """
+                                    While universal2 wheels can be built on x86_64, the arm64 part
+                                    of them cannot currently be tested. The ability to test the
+                                    arm64 part of a universal2 wheel will be added in a future
+                                    release of cibuildwheel, once Apple Silicon CI runners are
+                                    widely available. To silence this warning, set
+                                    `CIBW_TEST_SKIP: *-macosx_universal2:arm64`.
+                                    """
+                                )
+                            )
                        else:
-                            raise RuntimeError('unreachable')
+                            raise RuntimeError("unreachable")

                        # skip this test
                        continue

-                    log.step('Testing wheel...' if testing_arch == machine_arch else f'Testing wheel on {testing_arch}...')
+                    log.step(
+                        "Testing wheel..."
+                        if testing_arch == machine_arch
+                        else f"Testing wheel on {testing_arch}..."
+                    )

                    # set up a virtual environment to install and test from, to make sure
                    # there are no dependencies that were pulled in at build time.
-                    call(['pip', 'install', 'virtualenv', *dependency_constraint_flags], env=env)
+                    call(["pip", "install", "virtualenv", *dependency_constraint_flags], env=env)
                    venv_dir = Path(tempfile.mkdtemp())

                    arch_prefix = []
                    if testing_arch != machine_arch:
-                        if machine_arch == 'arm64' and testing_arch == 'x86_64':
+                        if machine_arch == "arm64" and testing_arch == "x86_64":
                            # rosetta2 will provide the emulation with just the arch prefix.
-                            arch_prefix = ['arch', '-x86_64']
+                            arch_prefix = ["arch", "-x86_64"]
                        else:
-                            raise RuntimeError("don't know how to emulate {testing_arch} on {machine_arch}")
+                            raise RuntimeError(
+                                "don't know how to emulate {testing_arch} on {machine_arch}"
+                            )

                    # define a custom 'call' function that adds the arch prefix each time
                    def call_with_arch(args: Sequence[PathOrStr], **kwargs: Any) -> None:
                        if isinstance(args, str):
-                            args = ' '.join(arch_prefix) + ' ' + args
+                            args = " ".join(arch_prefix) + " " + args
                        else:
                            args = [*arch_prefix, *args]
                        call(args, **kwargs)

                    # Use --no-download to ensure determinism by using seed libraries
                    # built into virtualenv
-                    call_with_arch(['python', '-m', 'virtualenv', '--no-download', venv_dir], env=env)
+                    call_with_arch(
+                        ["python", "-m", "virtualenv", "--no-download", venv_dir], env=env
+                    )

                    virtualenv_env = env.copy()
-                    virtualenv_env['PATH'] = os.pathsep.join([
-                        str(venv_dir / 'bin'),
-                        virtualenv_env['PATH'],
-                    ])
+                    virtualenv_env["PATH"] = os.pathsep.join(
+                        [
+                            str(venv_dir / "bin"),
+                            virtualenv_env["PATH"],
+                        ]
+                    )

                    # check that we are using the Python from the virtual environment
-                    call_with_arch(['which', 'python'], env=virtualenv_env)
+                    call_with_arch(["which", "python"], env=virtualenv_env)

                    if options.before_test:
-                        before_test_prepared = prepare_command(options.before_test, project='.', package=options.package_dir)
+                        before_test_prepared = prepare_command(
+                            options.before_test, project=".", package=options.package_dir
+                        )
                        call_with_arch(before_test_prepared, env=virtualenv_env, shell=True)

                    # install the wheel
-                    call_with_arch(['pip', 'install', f"{repaired_wheel}{options.test_extras}"], env=virtualenv_env)
+                    call_with_arch(
+                        ["pip", "install", f"{repaired_wheel}{options.test_extras}"],
+                        env=virtualenv_env,
+                    )

                    # test the wheel
                    if options.test_requires:
-                        call_with_arch(['pip', 'install'] + options.test_requires, env=virtualenv_env)
+                        call_with_arch(
+                            ["pip", "install"] + options.test_requires, env=virtualenv_env
+                        )

                    # run the tests from $HOME, with an absolute path in the command
                    # (this ensures that Python runs the tests against the installed wheel
                    # and not the repo code)
                    test_command_prepared = prepare_command(
                        options.test_command,
-                        project=Path('.').resolve(),
-                        package=options.package_dir.resolve()
+                        project=Path(".").resolve(),
+                        package=options.package_dir.resolve(),
+                    )
+                    call_with_arch(
+                        test_command_prepared,
+                        cwd=os.environ["HOME"],
+                        env=virtualenv_env,
+                        shell=True,
                    )
-                    call_with_arch(test_command_prepared, cwd=os.environ['HOME'], env=virtualenv_env, shell=True)

                    # clean up
                    shutil.rmtree(venv_dir)
@@ -469,5 +602,7 @@ def build(options: BuildOptions) -> None:
            shutil.move(str(repaired_wheel), options.output_dir)
            log.build_end()
    except subprocess.CalledProcessError as error:
-        log.step_end_with_error(f'Command {error.cmd} failed with code {error.returncode}. {error.stdout}')
+        log.step_end_with_error(
+            f"Command {error.cmd} failed with code {error.returncode}. {error.stdout}"
+        )
        sys.exit(1)
@@ -0,0 +1,171 @@
+import os
+from pathlib import Path
+from typing import Any, Dict, List, Mapping, Optional, Set, Tuple, Union
+
+import toml
+
+from .typing import PLATFORMS, TypedDict
+from .util import resources_dir
+
+Setting = Union[Dict[str, str], List[str], str]
+
+
+class TableFmt(TypedDict):
+    item: str
+    sep: str
+
+
+class ConfigOptionError(KeyError):
+    pass
+
+
+def _dig_first(*pairs: Tuple[Mapping[str, Any], str]) -> Setting:
+    """
+    Return the first dict item that matches from pairs of dicts and keys.
+    Final result is will throw a KeyError if missing.
+
+    _dig_first((dict1, "key1"), (dict2, "key2"), ...)
+    """
+    (dict_like, key), *others = pairs
+    return dict_like.get(key, _dig_first(*others)) if others else dict_like[key]
+
+
+class ConfigOptions:
+    """
+    Gets options from the environment, config or defaults, optionally scoped
+    by the platform.
+
+    Example:
+      >>> options = ConfigOptions(package_dir, platform='macos')
+      >>> options('cool-color')
+
+      This will return the value of CIBW_COOL_COLOR_MACOS if it exists,
+      otherwise the value of CIBW_COOL_COLOR, otherwise
+      'tool.cibuildwheel.macos.cool-color' or 'tool.cibuildwheel.cool-color'
+      from pyproject.toml, or from cibuildwheel/resources/defaults.toml. An
+      error is thrown if there are any unexpected keys or sections in
+      tool.cibuildwheel.
+    """
+
+    def __init__(
+        self,
+        package_path: Path,
+        config_file: Optional[str] = None,
+        *,
+        platform: str,
+        disallow: Optional[Dict[str, Set[str]]] = None,
+    ) -> None:
+        self.platform = platform
+        self.disallow = disallow or {}
+
+        # Open defaults.toml, loading both global and platform sections
+        defaults_path = resources_dir / "defaults.toml"
+        self.default_options, self.default_platform_options = self._load_file(defaults_path)
+
+        # load the project config file
+        config_options: Dict[str, Any] = {}
+        config_platform_options: Dict[str, Any] = {}
+
+        if config_file is not None:
+            config_path = Path(config_file.format(package=package_path))
+            config_options, config_platform_options = self._load_file(config_path)
+        else:
+            # load pyproject.toml, if it's available
+            pyproject_toml_path = package_path / "pyproject.toml"
+            if pyproject_toml_path.exists():
+                config_options, config_platform_options = self._load_file(pyproject_toml_path)
+
+        # validate project config
+        for option_name in config_options:
+            if not self._is_valid_global_option(option_name):
+                raise ConfigOptionError(f'Option "{option_name}" not supported in a config file')
+
+        for option_name in config_platform_options:
+            if not self._is_valid_platform_option(option_name):
+                raise ConfigOptionError(
+                    f'Option "{option_name}" not supported in the "{self.platform}" section'
+                )
+
+        self.config_options = config_options
+        self.config_platform_options = config_platform_options
+
+    def _is_valid_global_option(self, name: str) -> bool:
+        """
+        Returns True if an option with this name is allowed in the
+        [tool.cibuildwheel] section of a config file.
+        """
+        allowed_option_names = self.default_options.keys() | PLATFORMS
+
+        return name in allowed_option_names
+
+    def _is_valid_platform_option(self, name: str) -> bool:
+        """
+        Returns True if an option with this name is allowed in the
+        [tool.cibuildwheel.<current-platform>] section of a config file.
+        """
+        disallowed_platform_options = self.disallow.get(self.platform, set())
+        if name in disallowed_platform_options:
+            return False
+
+        allowed_option_names = self.default_options.keys() | self.default_platform_options.keys()
+
+        return name in allowed_option_names
+
+    def _load_file(self, filename: Path) -> Tuple[Dict[str, Any], Dict[str, Any]]:
+        """
+        Load a toml file, returns global and platform as separate dicts.
+        """
+        config = toml.load(filename)
+
+        global_options = config.get("tool", {}).get("cibuildwheel", {})
+        platform_options = global_options.get(self.platform, {})
+
+        return global_options, platform_options
+
+    def __call__(
+        self,
+        name: str,
+        *,
+        env_plat: bool = True,
+        sep: Optional[str] = None,
+        table: Optional[TableFmt] = None,
+    ) -> str:
+        """
+        Get and return the value for the named option from environment,
+        configuration file, or the default. If env_plat is False, then don't
+        accept platform versions of the environment variable. If this is an
+        array it will be merged with "sep" before returning. If it is a table,
+        it will be formatted with "table['item']" using {k} and {v} and merged
+        with "table['sep']".
+        """
+
+        if name not in self.default_options and name not in self.default_platform_options:
+            raise ConfigOptionError(f"{name} must be in cibuildwheel/resources/defaults.toml file")
+
+        # Environment variable form
+        envvar = f"CIBW_{name.upper().replace('-', '_')}"
+        plat_envvar = f"{envvar}_{self.platform.upper()}"
+
+        # get the option from the environment, then the config file, then finally the default.
+        # platform-specific options are preferred, if they're allowed.
+        result = _dig_first(
+            (os.environ if env_plat else {}, plat_envvar),  # type: ignore
+            (os.environ, envvar),
+            (self.config_platform_options, name),
+            (self.config_options, name),
+            (self.default_platform_options, name),
+            (self.default_options, name),
+        )
+
+        if isinstance(result, dict):
+            if table is None:
+                raise ConfigOptionError(f"{name} does not accept a table")
+            return table["sep"].join(table["item"].format(k=k, v=v) for k, v in result.items())
+        elif isinstance(result, list):
+            if sep is None:
+                raise ConfigOptionError(f"{name} does not accept a list")
+            return sep.join(result)
+        elif isinstance(result, int):
+            return str(result)
+        else:
+            return result
@@ -35,9 +35,8 @@ class Analyzer(ast.NodeVisitor):
        if node.arg == "python_requires":
            # Must not be nested in an if or other structure
            # This will be Module -> Expr -> Call -> keyword
-            if (
-                not hasattr(node.parent.parent.parent, "parent")  # type: ignore
-                and isinstance(node.value, Constant)
+            if not hasattr(node.parent.parent.parent, "parent") and isinstance(  # type: ignore
+                node.value, Constant
            ):
                self.requires_python = get_constant(node.value)

@@ -57,21 +56,21 @@ def get_requires_python_str(package_dir: Path) -> Optional[str]:

    # Read in from pyproject.toml:project.requires-python
    try:
-        info = toml.load(package_dir / 'pyproject.toml')
-        return str(info['project']['requires-python'])
+        info = toml.load(package_dir / "pyproject.toml")
+        return str(info["project"]["requires-python"])
    except (FileNotFoundError, KeyError, IndexError, TypeError):
        pass

    # Read in from setup.cfg:options.python_requires
    try:
        config = ConfigParser()
-        config.read(package_dir / 'setup.cfg')
-        return str(config['options']['python_requires'])
+        config.read(package_dir / "setup.cfg")
+        return str(config["options"]["python_requires"])
    except (FileNotFoundError, KeyError, IndexError, TypeError):
        pass

    try:
-        with open(package_dir / 'setup.py') as f:
+        with open(package_dir / "setup.py") as f:
            return setup_py_python_requires(f.read())
    except FileNotFoundError:
        pass
@@ -1,69 +1,62 @@
 [linux]
 python_configurations = [
-  { identifier = "cp27-manylinux_x86_64", version = "2.7", path_str = "/opt/python/cp27-cp27m" },
-  { identifier = "cp27-manylinux_x86_64", version = "2.7", path_str = "/opt/python/cp27-cp27mu" },
-  { identifier = "cp35-manylinux_x86_64", version = "3.5", path_str = "/opt/python/cp35-cp35m" },
  { identifier = "cp36-manylinux_x86_64", version = "3.6", path_str = "/opt/python/cp36-cp36m" },
  { identifier = "cp37-manylinux_x86_64", version = "3.7", path_str = "/opt/python/cp37-cp37m" },
  { identifier = "cp38-manylinux_x86_64", version = "3.8", path_str = "/opt/python/cp38-cp38" },
  { identifier = "cp39-manylinux_x86_64", version = "3.9", path_str = "/opt/python/cp39-cp39" },
-  { identifier = "cp27-manylinux_i686", version = "2.7", path_str = "/opt/python/cp27-cp27m" },
-  { identifier = "cp27-manylinux_i686", version = "2.7", path_str = "/opt/python/cp27-cp27mu" },
-  { identifier = "cp35-manylinux_i686", version = "3.5", path_str = "/opt/python/cp35-cp35m" },
+  { identifier = "cp310-manylinux_x86_64", version = "3.10", path_str = "/opt/python/cp310-cp310" },
  { identifier = "cp36-manylinux_i686", version = "3.6", path_str = "/opt/python/cp36-cp36m" },
  { identifier = "cp37-manylinux_i686", version = "3.7", path_str = "/opt/python/cp37-cp37m" },
  { identifier = "cp38-manylinux_i686", version = "3.8", path_str = "/opt/python/cp38-cp38" },
  { identifier = "cp39-manylinux_i686", version = "3.9", path_str = "/opt/python/cp39-cp39" },
-  { identifier = "pp27-manylinux_x86_64", version = "2.7", path_str = "/opt/python/pp27-pypy_73" },
-  { identifier = "pp36-manylinux_x86_64", version = "3.6", path_str = "/opt/python/pp36-pypy36_pp73" },
+  { identifier = "cp310-manylinux_i686", version = "3.10", path_str = "/opt/python/cp310-cp310" },
  { identifier = "pp37-manylinux_x86_64", version = "3.7", path_str = "/opt/python/pp37-pypy37_pp73" },
-  { identifier = "cp35-manylinux_aarch64", version = "3.5", path_str = "/opt/python/cp35-cp35m" },
  { identifier = "cp36-manylinux_aarch64", version = "3.6", path_str = "/opt/python/cp36-cp36m" },
  { identifier = "cp37-manylinux_aarch64", version = "3.7", path_str = "/opt/python/cp37-cp37m" },
  { identifier = "cp38-manylinux_aarch64", version = "3.8", path_str = "/opt/python/cp38-cp38" },
  { identifier = "cp39-manylinux_aarch64", version = "3.9", path_str = "/opt/python/cp39-cp39" },
-  { identifier = "cp35-manylinux_ppc64le", version = "3.5", path_str = "/opt/python/cp35-cp35m" },
+  { identifier = "cp310-manylinux_aarch64", version = "3.10", path_str = "/opt/python/cp310-cp310" },
  { identifier = "cp36-manylinux_ppc64le", version = "3.6", path_str = "/opt/python/cp36-cp36m" },
  { identifier = "cp37-manylinux_ppc64le", version = "3.7", path_str = "/opt/python/cp37-cp37m" },
  { identifier = "cp38-manylinux_ppc64le", version = "3.8", path_str = "/opt/python/cp38-cp38" },
  { identifier = "cp39-manylinux_ppc64le", version = "3.9", path_str = "/opt/python/cp39-cp39" },
-  { identifier = "cp35-manylinux_s390x", version = "3.5", path_str = "/opt/python/cp35-cp35m" },
+  { identifier = "cp310-manylinux_ppc64le", version = "3.10", path_str = "/opt/python/cp310-cp310" },
  { identifier = "cp36-manylinux_s390x", version = "3.6", path_str = "/opt/python/cp36-cp36m" },
  { identifier = "cp37-manylinux_s390x", version = "3.7", path_str = "/opt/python/cp37-cp37m" },
  { identifier = "cp38-manylinux_s390x", version = "3.8", path_str = "/opt/python/cp38-cp38" },
  { identifier = "cp39-manylinux_s390x", version = "3.9", path_str = "/opt/python/cp39-cp39" },
+  { identifier = "cp310-manylinux_s390x", version = "3.10", path_str = "/opt/python/cp310-cp310" },
+  { identifier = "pp37-manylinux_aarch64", version = "3.7", path_str = "/opt/python/pp37-pypy37_pp73" },
+  { identifier = "pp37-manylinux_i686", version = "3.7", path_str = "/opt/python/pp37-pypy37_pp73" },
 ]

 [macos]
 python_configurations = [
-  { identifier = "cp27-macosx_x86_64", version = "2.7", url = "https://www.python.org/ftp/python/2.7.18/python-2.7.18-macosx10.9.pkg" },
-  { identifier = "cp35-macosx_x86_64", version = "3.5", url = "https://www.python.org/ftp/python/3.5.4/python-3.5.4-macosx10.6.pkg" },
  { identifier = "cp36-macosx_x86_64", version = "3.6", url = "https://www.python.org/ftp/python/3.6.8/python-3.6.8-macosx10.9.pkg" },
  { identifier = "cp37-macosx_x86_64", version = "3.7", url = "https://www.python.org/ftp/python/3.7.9/python-3.7.9-macosx10.9.pkg" },
-  { identifier = "cp38-macosx_x86_64", version = "3.8", url = "https://www.python.org/ftp/python/3.8.9/python-3.8.9-macosx10.9.pkg" },
-  { identifier = "cp39-macosx_x86_64", version = "3.9", url = "https://www.python.org/ftp/python/3.9.4/python-3.9.4-macos11.pkg" },
-  { identifier = "cp39-macosx_arm64", version = "3.9", url = "https://www.python.org/ftp/python/3.9.4/python-3.9.4-macos11.pkg" },
-  { identifier = "cp39-macosx_universal2", version = "3.9", url = "https://www.python.org/ftp/python/3.9.4/python-3.9.4-macos11.pkg" },
-  { identifier = "pp27-macosx_x86_64", version = "2.7", url = "https://downloads.python.org/pypy/pypy2.7-v7.3.3-osx64.tar.bz2" },
-  { identifier = "pp36-macosx_x86_64", version = "3.6", url = "https://downloads.python.org/pypy/pypy3.6-v7.3.3-osx64.tar.bz2" },
-  { identifier = "pp37-macosx_x86_64", version = "3.7", url = "https://downloads.python.org/pypy/pypy3.7-v7.3.3-osx64.tar.bz2" },
+  { identifier = "cp38-macosx_x86_64", version = "3.8", url = "https://www.python.org/ftp/python/3.8.10/python-3.8.10-macosx10.9.pkg" },
+  { identifier = "cp38-macosx_arm64", version = "3.8", url = "https://www.python.org/ftp/python/3.8.10/python-3.8.10-macosx10.9.pkg" },
+  { identifier = "cp38-macosx_universal2", version = "3.8", url = "https://www.python.org/ftp/python/3.8.10/python-3.8.10-macosx10.9.pkg" },
+  { identifier = "cp39-macosx_x86_64", version = "3.9", url = "https://www.python.org/ftp/python/3.9.6/python-3.9.6-macos11.pkg" },
+  { identifier = "cp39-macosx_arm64", version = "3.9", url = "https://www.python.org/ftp/python/3.9.6/python-3.9.6-macos11.pkg" },
+  { identifier = "cp39-macosx_universal2", version = "3.9", url = "https://www.python.org/ftp/python/3.9.6/python-3.9.6-macos11.pkg" },
+  { identifier = "cp310-macosx_x86_64", version = "3.10", url = "https://www.python.org/ftp/python/3.10.0/python-3.10.0b3-macos11.pkg" },
+  { identifier = "cp310-macosx_arm64", version = "3.10", url = "https://www.python.org/ftp/python/3.10.0/python-3.10.0b3-macos11.pkg" },
+  { identifier = "cp310-macosx_universal2", version = "3.10", url = "https://www.python.org/ftp/python/3.10.0/python-3.10.0b3-macos11.pkg" },
+  { identifier = "pp37-macosx_x86_64", version = "3.7", url = "https://downloads.python.org/pypy/pypy3.7-v7.3.5-osx64.tar.bz2" },
 ]

 [windows]
 python_configurations = [
-  { identifier = "cp27-win32", version = "2.7.18", arch = "32" },
-  { identifier = "cp27-win_amd64", version = "2.7.18", arch = "64" },
-  { identifier = "cp35-win32", version = "3.5.4", arch = "32" },
-  { identifier = "cp35-win_amd64", version = "3.5.4", arch = "64" },
  { identifier = "cp36-win32", version = "3.6.8", arch = "32" },
  { identifier = "cp36-win_amd64", version = "3.6.8", arch = "64" },
  { identifier = "cp37-win32", version = "3.7.9", arch = "32" },
  { identifier = "cp37-win_amd64", version = "3.7.9", arch = "64" },
-  { identifier = "cp38-win32", version = "3.8.9", arch = "32" },
-  { identifier = "cp38-win_amd64", version = "3.8.9", arch = "64" },
-  { identifier = "cp39-win32", version = "3.9.4", arch = "32" },
-  { identifier = "cp39-win_amd64", version = "3.9.4", arch = "64" },
-  { identifier = "pp27-win32", version = "2.7", arch = "32", url = "https://downloads.python.org/pypy/pypy2.7-v7.3.3-win32.zip" },
-  { identifier = "pp36-win32", version = "3.6", arch = "32", url = "https://downloads.python.org/pypy/pypy3.6-v7.3.3-win32.zip" },
-  { identifier = "pp37-win32", version = "3.7", arch = "32", url = "https://downloads.python.org/pypy/pypy3.7-v7.3.3-win32.zip" },
+  { identifier = "cp38-win32", version = "3.8.10", arch = "32" },
+  { identifier = "cp38-win_amd64", version = "3.8.10", arch = "64" },
+  { identifier = "cp39-win32", version = "3.9.6", arch = "32" },
+  { identifier = "cp39-win_amd64", version = "3.9.6", arch = "64" },
+  { identifier = "cp310-win32", version = "3.10.0-b3", arch = "32" },
+  { identifier = "cp310-win_amd64", version = "3.10.0-b3", arch = "64" },
+  { identifier = "pp37-win_amd64", version = "3.7", arch = "64", url = "https://downloads.python.org/pypy/pypy3.7-v7.3.5-win64.zip" },
 ]
@@ -1,55 +0,0 @@
-#
-# This file is autogenerated by pip-compile
-# To update, run:
-#
-#    bin/update_dependencies.py
-#
-appdirs==1.4.4
-    # via virtualenv
-configparser==4.0.2
-    # via importlib-metadata
-contextlib2==0.6.0.post1
-    # via
-    #   importlib-metadata
-    #   importlib-resources
-delocate==0.8.2
-    # via -r cibuildwheel/resources/constraints.in
-distlib==0.3.1
-    # via virtualenv
-filelock==3.0.12
-    # via virtualenv
-importlib-metadata==2.1.1
-    # via virtualenv
-importlib-resources==3.3.1
-    # via virtualenv
-pathlib2==2.3.5
-    # via
-    #   importlib-metadata
-    #   importlib-resources
-    #   virtualenv
-scandir==1.10.0
-    # via pathlib2
-singledispatch==3.6.1
-    # via importlib-resources
-six==1.15.0
-    # via
-    #   pathlib2
-    #   virtualenv
-typing==3.7.4.3
-    # via importlib-resources
-virtualenv==20.4.3
-    # via -r cibuildwheel/resources/constraints.in
-wheel==0.36.2
-    # via
-    #   -r cibuildwheel/resources/constraints.in
-    #   delocate
-zipp==1.2.0
-    # via
-    #   importlib-metadata
-    #   importlib-resources
-
-# The following packages are considered to be unsafe in a requirements file:
-pip==20.3.4
-    # via -r cibuildwheel/resources/constraints.in
-setuptools==44.1.1
-    # via -r cibuildwheel/resources/constraints.in
@@ -1,36 +0,0 @@
-#
-# This file is autogenerated by pip-compile
-# To update, run:
-#
-#    bin/update_dependencies.py
-#
-appdirs==1.4.4
-    # via virtualenv
-delocate==0.8.2
-    # via -r cibuildwheel/resources/constraints.in
-distlib==0.3.1
-    # via virtualenv
-filelock==3.0.12
-    # via virtualenv
-importlib-metadata==2.1.1
-    # via virtualenv
-importlib-resources==3.2.1
-    # via virtualenv
-six==1.15.0
-    # via virtualenv
-virtualenv==20.4.3
-    # via -r cibuildwheel/resources/constraints.in
-wheel==0.36.2
-    # via
-    #   -r cibuildwheel/resources/constraints.in
-    #   delocate
-zipp==1.2.0
-    # via
-    #   importlib-metadata
-    #   importlib-resources
-
-# The following packages are considered to be unsafe in a requirements file:
-pip==20.3.4
-    # via -r cibuildwheel/resources/constraints.in
-setuptools==50.3.2
-    # via -r cibuildwheel/resources/constraints.in
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile
+# This file is autogenerated by pip-compile with python 3.6
 # To update, run:
 #
 #    bin/update_dependencies.py
@@ -8,31 +8,31 @@ appdirs==1.4.4
    # via virtualenv
 delocate==0.8.2
    # via -r cibuildwheel/resources/constraints.in
-distlib==0.3.1
+distlib==0.3.2
    # via virtualenv
 filelock==3.0.12
    # via virtualenv
-importlib-metadata==3.10.0
+importlib-metadata==4.6.1
    # via virtualenv
-importlib-resources==5.1.2
+importlib-resources==5.2.0
    # via virtualenv
-six==1.15.0
+six==1.16.0
    # via virtualenv
-typing-extensions==3.7.4.3
+typing-extensions==3.10.0.0
    # via importlib-metadata
-virtualenv==20.4.3
+virtualenv==20.4.7
    # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
    # via
    #   -r cibuildwheel/resources/constraints.in
    #   delocate
-zipp==3.4.1
+zipp==3.5.0
    # via
    #   importlib-metadata
    #   importlib-resources

 # The following packages are considered to be unsafe in a requirements file:
-pip==21.0.1
+pip==21.1.3
    # via -r cibuildwheel/resources/constraints.in
-setuptools==54.2.0
+setuptools==57.1.0
    # via -r cibuildwheel/resources/constraints.in
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile
+# This file is autogenerated by pip-compile with python 3.7
 # To update, run:
 #
 #    bin/update_dependencies.py
@@ -8,27 +8,27 @@ appdirs==1.4.4
    # via virtualenv
 delocate==0.8.2
    # via -r cibuildwheel/resources/constraints.in
-distlib==0.3.1
+distlib==0.3.2
    # via virtualenv
 filelock==3.0.12
    # via virtualenv
-importlib-metadata==3.10.0
+importlib-metadata==4.6.1
    # via virtualenv
-six==1.15.0
+six==1.16.0
    # via virtualenv
-typing-extensions==3.7.4.3
+typing-extensions==3.10.0.0
    # via importlib-metadata
-virtualenv==20.4.3
+virtualenv==20.4.7
    # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
    # via
    #   -r cibuildwheel/resources/constraints.in
    #   delocate
-zipp==3.4.1
+zipp==3.5.0
    # via importlib-metadata

 # The following packages are considered to be unsafe in a requirements file:
-pip==21.0.1
+pip==21.1.3
    # via -r cibuildwheel/resources/constraints.in
-setuptools==54.2.0
+setuptools==57.1.0
    # via -r cibuildwheel/resources/constraints.in
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile
+# This file is autogenerated by pip-compile with python 3.8
 # To update, run:
 #
 #    bin/update_dependencies.py
@@ -8,13 +8,13 @@ appdirs==1.4.4
    # via virtualenv
 delocate==0.8.2
    # via -r cibuildwheel/resources/constraints.in
-distlib==0.3.1
+distlib==0.3.2
    # via virtualenv
 filelock==3.0.12
    # via virtualenv
-six==1.15.0
+six==1.16.0
    # via virtualenv
-virtualenv==20.4.3
+virtualenv==20.4.7
    # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
    # via
@@ -22,7 +22,7 @@ wheel==0.36.2
    #   delocate

 # The following packages are considered to be unsafe in a requirements file:
-pip==21.0.1
+pip==21.1.3
    # via -r cibuildwheel/resources/constraints.in
-setuptools==54.2.0
+setuptools==57.1.0
    # via -r cibuildwheel/resources/constraints.in
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile
+# This file is autogenerated by pip-compile with python 3.9
 # To update, run:
 #
 #    bin/update_dependencies.py
@@ -8,13 +8,13 @@ appdirs==1.4.4
    # via virtualenv
 delocate==0.8.2
    # via -r cibuildwheel/resources/constraints.in
-distlib==0.3.1
+distlib==0.3.2
    # via virtualenv
 filelock==3.0.12
    # via virtualenv
-six==1.15.0
+six==1.16.0
    # via virtualenv
-virtualenv==20.4.3
+virtualenv==20.4.7
    # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
    # via
@@ -22,7 +22,7 @@ wheel==0.36.2
    #   delocate

 # The following packages are considered to be unsafe in a requirements file:
-pip==21.0.1
+pip==21.1.3
    # via -r cibuildwheel/resources/constraints.in
-setuptools==54.2.0
+setuptools==57.1.0
    # via -r cibuildwheel/resources/constraints.in
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile
+# This file is autogenerated by pip-compile with python 3.9
 # To update, run:
 #
 #    bin/update_dependencies.py
@@ -8,13 +8,13 @@ appdirs==1.4.4
    # via virtualenv
 delocate==0.8.2
    # via -r cibuildwheel/resources/constraints.in
-distlib==0.3.1
+distlib==0.3.2
    # via virtualenv
 filelock==3.0.12
    # via virtualenv
-six==1.15.0
+six==1.16.0
    # via virtualenv
-virtualenv==20.4.3
+virtualenv==20.4.7
    # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
    # via
@@ -22,7 +22,7 @@ wheel==0.36.2
    #   delocate

 # The following packages are considered to be unsafe in a requirements file:
-pip==21.0.1
+pip==21.1.3
    # via -r cibuildwheel/resources/constraints.in
-setuptools==54.2.0
+setuptools==57.1.0
    # via -r cibuildwheel/resources/constraints.in
@@ -0,0 +1,40 @@
+[tool.cibuildwheel]
+build = "*"
+skip = ""
+test-skip = ""
+
+archs = ["auto"]
+build-frontend = "pip"
+dependency-versions = "pinned"
+environment = {}
+build-verbosity = ""
+
+before-all = ""
+before-build = ""
+repair-wheel-command = ""
+
+test-command = ""
+before-test = ""
+test-requires = []
+test-extras = []
+
+manylinux-x86_64-image = "manylinux2010"
+manylinux-i686-image = "manylinux2010"
+manylinux-aarch64-image = "manylinux2014"
+manylinux-ppc64le-image = "manylinux2014"
+manylinux-s390x-image = "manylinux2014"
+manylinux-pypy_x86_64-image = "manylinux2010"
+manylinux-pypy_i686-image = "manylinux2010"
+manylinux-pypy_aarch64-image = "manylinux2014"
+
+
+[tool.cibuildwheel.linux]
+repair-wheel-command = "auditwheel repair -w {dest_dir} {wheel}"
+
+[tool.cibuildwheel.macos]
+repair-wheel-command = [
+  "delocate-listdeps {wheel}",
+  "delocate-wheel --require-archs {delocate_archs} -w {dest_dir} {wheel}",
+]
+
+[tool.cibuildwheel.windows]
@@ -13,20 +13,24 @@ import stat
 import subprocess
 import sys

-STAT_0o775 = (stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR
-              | stat.S_IRGRP | stat.S_IWGRP | stat.S_IXGRP
-              | stat.S_IROTH | stat.S_IXOTH)
-
-if sys.version_info[0] == 2:
-    FileNotFoundError = OSError
+STAT_0o775 = (
+    stat.S_IRUSR
+    | stat.S_IWUSR
+    | stat.S_IXUSR
+    | stat.S_IRGRP
+    | stat.S_IWGRP
+    | stat.S_IXGRP
+    | stat.S_IROTH
+    | stat.S_IXOTH
+)


 def main():
-    openssl_dir, openssl_cafile = os.path.split(
-        ssl.get_default_verify_paths().openssl_cafile)
+    openssl_dir, openssl_cafile = os.path.split(ssl.get_default_verify_paths().openssl_cafile)
    print(" -- pip install --upgrade certifi")
-    subprocess.check_call([sys.executable,
-                           "-E", "-s", "-m", "pip", "install", "--upgrade", "certifi"])
+    subprocess.check_call(
+        [sys.executable, "-E", "-s", "-m", "pip", "install", "--upgrade", "certifi"]
+    )

    import certifi

@@ -47,5 +51,5 @@ def main():
    print(" -- update complete")


-if __name__ == '__main__':
+if __name__ == "__main__":
    main()
@@ -1,27 +1,38 @@
 [x86_64]
-manylinux1 = quay.io/pypa/manylinux1_x86_64:2021-04-05-14df3a6
-manylinux2010 = quay.io/pypa/manylinux2010_x86_64:2021-02-06-3d322a5
-manylinux2014 = quay.io/pypa/manylinux2014_x86_64:2021-04-05-b4fd19d
-manylinux_2_24 = quay.io/pypa/manylinux_2_24_x86_64:2021-04-05-b4fd19d
+manylinux1 = quay.io/pypa/manylinux1_x86_64:2021-07-04-13bcf48
+manylinux2010 = quay.io/pypa/manylinux2010_x86_64:2021-07-04-1e3ce39
+manylinux2014 = quay.io/pypa/manylinux2014_x86_64:2021-07-04-1e3ce39
+manylinux_2_24 = quay.io/pypa/manylinux_2_24_x86_64:2021-07-04-1e3ce39

 [i686]
-manylinux1 = quay.io/pypa/manylinux1_i686:2021-04-05-14df3a6
-manylinux2010 = quay.io/pypa/manylinux2010_i686:2021-02-06-3d322a5
-manylinux2014 = quay.io/pypa/manylinux2014_i686:2021-04-05-b4fd19d
-manylinux_2_24 = quay.io/pypa/manylinux_2_24_i686:2021-04-05-b4fd19d
+manylinux1 = quay.io/pypa/manylinux1_i686:2021-07-04-13bcf48
+manylinux2010 = quay.io/pypa/manylinux2010_i686:2021-07-04-1e3ce39
+manylinux2014 = quay.io/pypa/manylinux2014_i686:2021-07-04-1e3ce39
+manylinux_2_24 = quay.io/pypa/manylinux_2_24_i686:2021-07-04-1e3ce39

 [pypy_x86_64]
-manylinux2010 = pypywheels/manylinux2010-pypy_x86_64:2020-12-11-f1e0e80
+manylinux2010 = quay.io/pypa/manylinux2010_x86_64:2021-07-04-1e3ce39
+manylinux2014 = quay.io/pypa/manylinux2014_x86_64:2021-07-04-1e3ce39
+manylinux_2_24 = quay.io/pypa/manylinux_2_24_x86_64:2021-07-04-1e3ce39
+
+[pypy_i686]
+manylinux2010 = quay.io/pypa/manylinux2010_i686:2021-07-04-1e3ce39
+manylinux2014 = quay.io/pypa/manylinux2014_i686:2021-07-04-1e3ce39
+manylinux_2_24 = quay.io/pypa/manylinux_2_24_i686:2021-07-04-1e3ce39

 [aarch64]
-manylinux2014 = quay.io/pypa/manylinux2014_aarch64:2021-04-05-b4fd19d
-manylinux_2_24 = quay.io/pypa/manylinux_2_24_aarch64:2021-04-05-b4fd19d
+manylinux2014 = quay.io/pypa/manylinux2014_aarch64:2021-07-04-1e3ce39
+manylinux_2_24 = quay.io/pypa/manylinux_2_24_aarch64:2021-07-04-1e3ce39

 [ppc64le]
-manylinux2014 = quay.io/pypa/manylinux2014_ppc64le:2021-04-05-b4fd19d
-manylinux_2_24 = quay.io/pypa/manylinux_2_24_ppc64le:2021-04-05-b4fd19d
+manylinux2014 = quay.io/pypa/manylinux2014_ppc64le:2021-07-04-1e3ce39
+manylinux_2_24 = quay.io/pypa/manylinux_2_24_ppc64le:2021-07-04-1e3ce39

 [s390x]
-manylinux2014 = quay.io/pypa/manylinux2014_s390x:2021-04-05-b4fd19d
-manylinux_2_24 = quay.io/pypa/manylinux_2_24_s390x:2021-04-05-b4fd19d
+manylinux2014 = quay.io/pypa/manylinux2014_s390x:2021-07-04-1e3ce39
+manylinux_2_24 = quay.io/pypa/manylinux_2_24_s390x:2021-07-04-1e3ce39
+
+[pypy_aarch64]
+manylinux2014 = quay.io/pypa/manylinux2014_aarch64:2021-07-04-1e3ce39
+manylinux_2_24 = quay.io/pypa/manylinux_2_24_aarch64:2021-07-04-1e3ce39

@@ -1,36 +0,0 @@
-diff --git a/lib-python/3/sysconfig.py b/lib-python/3/sysconfig.py
-index 0d08cde66b4150e1772c13fdc6fe34d079c2b10d..30c77d165a2505d98bc7660ff0cc3b728f56c682 100644
--- a/lib-python/3/sysconfig.py
-+++ b/lib-python/3/sysconfig.py
-@@ -618,9 +618,6 @@ def get_config_vars(*args):
-             import _osx_support
-             _osx_support.customize_config_vars(_CONFIG_VARS)
-
-        _CONFIG_VARS['INCLUDEPY'] = os.path.join(_CONFIG_VARS['prefix'],
-                                                 'include')
-
-     if args:
-         vals = []
-         for name in args:
-diff --git a/lib_pypy/_sysconfigdata.py b/lib_pypy/_sysconfigdata.py
-index f1cca41a4b7553819bb1a2a63af1c1a9b8591ce9..a34216e8e12b82abd72fabdd7793b3e8bb19bbcf 100644
--- a/lib_pypy/_sysconfigdata.py
-+++ b/lib_pypy/_sysconfigdata.py
-@@ -5,6 +5,7 @@ from distutils.spawn import find_executable
-
- so_ext = _imp.extension_suffixes()[0]
-
-+mybase = os.path.dirname(os.path.dirname(__file__))
-
- build_time_vars = {
-     # SOABI is PEP 3149 compliant, but CPython3 has so_ext.split('.')[1]
-@@ -25,7 +26,8 @@ build_time_vars = {
-     'AR': "ar",
-     'ARFLAGS': "rc",
-     'EXE': "",
-    'LIBDIR': os.path.join(sys.prefix, 'bin'),
-+    'LIBDIR': os.path.join(mybase, 'lib'),
-+    'INCLUDEPY': os.path.join(mybase, 'include'),
- }
-
- if find_executable("gcc"):
@@ -1,27 +0,0 @@
--- a/lib-python/2.7/sysconfig.py
-+++ b/lib-python/2.7/sysconfig.py
-@@ -553,9 +553,6 @@ def get_config_vars(*args):
-             if type_ == imp.C_EXTENSION:
-                 _CONFIG_VARS['SOABI'] = suffix.split('.')[1]
-                 break
-        _CONFIG_VARS['INCLUDEPY'] = os.path.join(_CONFIG_VARS['prefix'],
-                                                 'include')
-
-     if args:
-         vals = []
-         for name in args:
--- a/lib_pypy/_sysconfigdata.py
-+++ b/lib_pypy/_sysconfigdata.py
-@@ -1,5 +1,11 @@
-import imp
-+import imp, os
-+
-+mybase = os.path.dirname(os.path.dirname(__file__))
-
- build_time_vars = {
-     "SO": [s[0] for s in imp.get_suffixes() if s[2] == imp.C_EXTENSION][0]
- }
-+
-+build_time_vars['LIBDIR'] = os.path.join(mybase, 'lib')
-+build_time_vars['INCLUDEPY'] = os.path.join(mybase, 'include')
-+
@@ -9,7 +9,18 @@ else:
    from typing import Final, Literal, TypedDict


-__all__ = ("Final", "Literal", "TypedDict", "Set", "Union", "PopenBytes", "PathOrStr", "PlatformName", "PLATFORMS", "assert_never")
+__all__ = (
+    "Final",
+    "Literal",
+    "TypedDict",
+    "Set",
+    "Union",
+    "PopenBytes",
+    "PathOrStr",
+    "PlatformName",
+    "PLATFORMS",
+    "assert_never",
+)


 if TYPE_CHECKING:
@@ -25,4 +36,4 @@ PLATFORMS: Final[Set[PlatformName]] = {"linux", "macos", "windows"}


 def assert_never(value: NoReturn) -> NoReturn:
-    assert False, f'Unhandled value: {value} ({type(value).__name__})'  # noqa: B011
+    assert False, f"Unhandled value: {value} ({type(value).__name__})"  # noqa: B011
@@ -4,6 +4,8 @@ import itertools
 import os
 import re
 import ssl
+import subprocess
+import sys
 import textwrap
 import time
 import urllib.request
@@ -20,37 +22,38 @@ from packaging.version import Version

 from .architecture import Architecture
 from .environment import ParsedEnvironment
-from .typing import PathOrStr, PlatformName
+from .typing import Literal, PathOrStr, PlatformName

-resources_dir = Path(__file__).parent / 'resources'
+resources_dir = Path(__file__).parent / "resources"

-get_pip_script = resources_dir / 'get-pip.py'
 install_certifi_script = resources_dir / "install_certifi.py"

+BuildFrontend = Literal["pip", "build"]
+

 def prepare_command(command: str, **kwargs: PathOrStr) -> str:
-    '''
+    """
    Preprocesses a command by expanding variables like {python}.

    For example, used in the test_command option to specify the path to the
    project's root.
-    '''
-    return command.format(python='python', pip='pip', **kwargs)
+    """
+    return command.format(python="python", pip="pip", **kwargs)


 def get_build_verbosity_extra_flags(level: int) -> List[str]:
    if level > 0:
-        return ['-' + level * 'v']
+        return ["-" + level * "v"]
    elif level < 0:
-        return ['-' + -level * 'q']
+        return ["-" + -level * "q"]
    else:
        return []


 def read_python_configs(config: PlatformName) -> List[Dict[str, str]]:
-    input_file = resources_dir / 'build-platforms.toml'
+    input_file = resources_dir / "build-platforms.toml"
    loaded_file = toml.load(input_file)
-    results: List[Dict[str, str]] = list(loaded_file[config]['python_configurations'])
+    results: List[Dict[str, str]] = list(loaded_file[config]["python_configurations"])
    return results


@@ -59,36 +62,66 @@ class IdentifierSelector:
    This class holds a set of build/skip patterns. You call an instance with a
    build identifier, and it returns True if that identifier should be
    included. Only call this on valid identifiers, ones that have at least 2
-    numeric digits before the first dash.
+    numeric digits before the first dash. If a pre-release version X.Y is present,
+    you can filter it with prerelease="XY".
    """

-    def __init__(self, *, build_config: str, skip_config: str, requires_python: Optional[SpecifierSet] = None):
+    # a pattern that skips prerelease versions, when include_prereleases is False.
+    PRERELEASE_SKIP = "cp310-*"
+
+    def __init__(
+        self,
+        *,
+        build_config: str,
+        skip_config: str,
+        requires_python: Optional[SpecifierSet] = None,
+        prerelease_pythons: bool = False,
+    ):
        self.build_patterns = build_config.split()
        self.skip_patterns = skip_config.split()
        self.requires_python = requires_python
+        self.prerelease_pythons = prerelease_pythons

    def __call__(self, build_id: str) -> bool:
        # Filter build selectors by python_requires if set
        if self.requires_python is not None:
-            py_ver_str = build_id.split('-')[0]
+            py_ver_str = build_id.split("-")[0]
            major = int(py_ver_str[2])
            minor = int(py_ver_str[3:])
            version = Version(f"{major}.{minor}.99")
            if not self.requires_python.contains(version):
                return False

-        build_patterns = itertools.chain.from_iterable(bracex.expand(p) for p in self.build_patterns)
-        skip_patterns = itertools.chain.from_iterable(bracex.expand(p) for p in self.skip_patterns)
+        build_patterns = itertools.chain.from_iterable(
+            bracex.expand(p) for p in self.build_patterns
+        )
+
+        unexpanded_skip_patterns = self.skip_patterns.copy()
+
+        if not self.prerelease_pythons:
+            # filter out the prerelease pythons, alongside the user-defined
+            # skip patterns
+            unexpanded_skip_patterns += BuildSelector.PRERELEASE_SKIP.split()
+
+        skip_patterns = itertools.chain.from_iterable(
+            bracex.expand(p) for p in unexpanded_skip_patterns
+        )

        build: bool = any(fnmatch.fnmatch(build_id, pat) for pat in build_patterns)
        skip: bool = any(fnmatch.fnmatch(build_id, pat) for pat in skip_patterns)
        return build and not skip

    def __repr__(self) -> str:
-        if not self.skip_patterns:
-            return f'{self.__class__.__name__}({" ".join(self.build_patterns)!r})'
-        else:
-            return f'{self.__class__.__name__}({" ".join(self.build_patterns)!r} - {" ".join(self.skip_patterns)!r})'
+        result = f'{self.__class__.__name__}(build_config={" ".join(self.build_patterns)!r}'
+
+        if self.skip_patterns:
+            result += f', skip_config={" ".join(self.skip_patterns)!r}'
+        if self.prerelease_pythons:
+            result += ", prerelease_pythons=True"
+
+        result += ")"
+
+        return result


 class BuildSelector(IdentifierSelector):
@@ -120,14 +153,14 @@ class Unbuffered:


 def download(url: str, dest: Path) -> None:
-    print(f'+ Download {url} to {dest}')
+    print(f"+ Download {url} to {dest}")
    dest_dir = dest.parent
    if not dest_dir.exists():
        dest_dir.mkdir(parents=True)

    # we've had issues when relying on the host OS' CA certificates on Windows,
    # so we use certifi (this sounds odd but requests also does this by default)
-    cafile = os.environ.get('SSL_CERT_FILE', certifi.where())
+    cafile = os.environ.get("SSL_CERT_FILE", certifi.where())
    context = ssl.create_default_context(cafile=cafile)
    repeat_num = 3
    for i in range(repeat_num):
@@ -152,17 +185,15 @@ class DependencyConstraints:
        self.base_file_path = base_file_path.resolve()

    @staticmethod
-    def with_defaults() -> 'DependencyConstraints':
-        return DependencyConstraints(
-            base_file_path=resources_dir / 'constraints.txt'
-        )
+    def with_defaults() -> "DependencyConstraints":
+        return DependencyConstraints(base_file_path=resources_dir / "constraints.txt")

    def get_for_python_version(self, version: str) -> Path:
-        version_parts = version.split('.')
+        version_parts = version.split(".")

        # try to find a version-specific dependency file e.g. if
-        # ./constraints.txt is the base, look for ./constraints-python27.txt
-        specific_stem = self.base_file_path.stem + f'-python{version_parts[0]}{version_parts[1]}'
+        # ./constraints.txt is the base, look for ./constraints-python36.txt
+        specific_stem = self.base_file_path.stem + f"-python{version_parts[0]}{version_parts[1]}"
        specific_name = specific_stem + self.base_file_path.suffix
        specific_file_path = self.base_file_path.with_name(specific_name)
        if specific_file_path.exists():
@@ -171,7 +202,7 @@ class DependencyConstraints:
            return self.base_file_path

    def __repr__(self) -> str:
-        return f'{self.__class__.__name__}{self.base_file_path!r})'
+        return f"{self.__class__.__name__}{self.base_file_path!r})"


 class BuildOptions(NamedTuple):
@@ -191,11 +222,13 @@ class BuildOptions(NamedTuple):
    test_requires: List[str]
    test_extras: str
    build_verbosity: int
+    build_frontend: BuildFrontend


 class NonPlatformWheelError(Exception):
    def __init__(self) -> None:
-        message = textwrap.dedent('''
+        message = textwrap.dedent(
+            """
            cibuildwheel: Build failed because a pure Python wheel was generated.

            If you intend to build a pure-Python wheel, you don't need cibuildwheel - use
@@ -203,64 +236,65 @@ class NonPlatformWheelError(Exception):

            If you expected a platform wheel, check your project configuration, or run
            cibuildwheel with CIBW_BUILD_VERBOSITY=1 to view build logs.
-        ''')
+            """
+        )

        super().__init__(message)


 def strtobool(val: str) -> bool:
-    return val.lower() in {'y', 'yes', 't', 'true', 'on', '1'}
+    return val.lower() in {"y", "yes", "t", "true", "on", "1"}


 class CIProvider(Enum):
-    travis_ci = 'travis'
-    appveyor = 'appveyor'
-    circle_ci = 'circle_ci'
-    azure_pipelines = 'azure_pipelines'
-    github_actions = 'github_actions'
-    gitlab = 'gitlab'
-    other = 'other'
+    travis_ci = "travis"
+    appveyor = "appveyor"
+    circle_ci = "circle_ci"
+    azure_pipelines = "azure_pipelines"
+    github_actions = "github_actions"
+    gitlab = "gitlab"
+    other = "other"


 def detect_ci_provider() -> Optional[CIProvider]:
-    if 'TRAVIS' in os.environ:
+    if "TRAVIS" in os.environ:
        return CIProvider.travis_ci
-    elif 'APPVEYOR' in os.environ:
+    elif "APPVEYOR" in os.environ:
        return CIProvider.appveyor
-    elif 'CIRCLECI' in os.environ:
+    elif "CIRCLECI" in os.environ:
        return CIProvider.circle_ci
-    elif 'AZURE_HTTP_USER_AGENT' in os.environ:
+    elif "AZURE_HTTP_USER_AGENT" in os.environ:
        return CIProvider.azure_pipelines
-    elif 'GITHUB_ACTIONS' in os.environ:
+    elif "GITHUB_ACTIONS" in os.environ:
        return CIProvider.github_actions
-    elif 'GITLAB_CI' in os.environ:
+    elif "GITLAB_CI" in os.environ:
        return CIProvider.gitlab
-    elif strtobool(os.environ.get('CI', 'false')):
+    elif strtobool(os.environ.get("CI", "false")):
        return CIProvider.other
    else:
        return None


 def unwrap(text: str) -> str:
-    '''
+    """
    Unwraps multi-line text to a single line
-    '''
+    """
    # remove initial line indent
    text = textwrap.dedent(text)
    # remove leading/trailing whitespace
    text = text.strip()
    # remove consecutive whitespace
-    return re.sub(r'\s+', ' ', text)
+    return re.sub(r"\s+", " ", text)


@contextlib.contextmanager
 def print_new_wheels(msg: str, output_dir: Path) -> Iterator[None]:
-    '''
+    """
    Prints the new items in a directory upon exiting. The message to display
    can include {n} for number of wheels, {s} for total number of seconds,
    and/or {m} for total number of minutes. Does not print anything if this
    exits via exception.
-    '''
+    """

    start_time = time.time()
    existing_contents = set(output_dir.iterdir())
@@ -271,3 +305,18 @@ def print_new_wheels(msg: str, output_dir: Path) -> Iterator[None]:
    s = time.time() - start_time
    m = s / 60
    print(msg.format(n=n, s=s, m=m), *sorted(f"  {f.name}" for f in new_contents), sep="\n")
+
+
+def get_pip_version(env: Dict[str, str]) -> str:
+    # we use shell=True here for windows, even though we don't need a shell due to a bug
+    # https://bugs.python.org/issue8557
+    shell = sys.platform.startswith("win")
+    versions_output_text = subprocess.check_output(
+        ["python", "-m", "pip", "freeze", "--all"], universal_newlines=True, shell=shell, env=env
+    )
+    (pip_version,) = (
+        version[5:]
+        for version in versions_output_text.strip().splitlines()
+        if version.startswith("pip==")
+    )
+    return pip_version
@@ -7,48 +7,53 @@ from pathlib import Path
 from typing import Dict, List, NamedTuple, Optional, Sequence, Set
 from zipfile import ZipFile

-import toml
-
 from .architecture import Architecture
 from .environment import ParsedEnvironment
 from .logger import log
-from .typing import PathOrStr
+from .typing import PathOrStr, assert_never
 from .util import (
+    BuildFrontend,
    BuildOptions,
    BuildSelector,
    NonPlatformWheelError,
    download,
    get_build_verbosity_extra_flags,
-    get_pip_script,
+    get_pip_version,
    prepare_command,
    read_python_configs,
 )

-IS_RUNNING_ON_AZURE = Path('C:\\hostedtoolcache').exists()
+CIBW_INSTALL_PATH = Path("C:\\cibw")


-def call(args: Sequence[PathOrStr], env: Optional[Dict[str, str]] = None,
-         cwd: Optional[str] = None) -> None:
-    print('+ ' + ' '.join(str(a) for a in args))
+def call(
+    args: Sequence[PathOrStr], env: Optional[Dict[str, str]] = None, cwd: Optional[PathOrStr] = None
+) -> None:
+    print("+ " + " ".join(str(a) for a in args))
    # we use shell=True here, even though we don't need a shell due to a bug
    # https://bugs.python.org/issue8557
    subprocess.run([str(a) for a in args], env=env, cwd=cwd, shell=True, check=True)


-def shell(command: str, env: Optional[Dict[str, str]] = None, cwd: Optional[str] = None) -> None:
-    print(f'+ {command}')
+def shell(
+    command: str, env: Optional[Dict[str, str]] = None, cwd: Optional[PathOrStr] = None
+) -> None:
+    print(f"+ {command}")
    subprocess.run(command, env=env, cwd=cwd, shell=True, check=True)


 def get_nuget_args(version: str, arch: str) -> List[str]:
-    python_name = 'python' if version[0] == '3' else 'python2'
-    if arch == '32':
-        python_name += 'x86'
+    python_name = "python"
+    if arch == "32":
+        python_name += "x86"
    return [
        python_name,
-        '-Version', version,
-        '-FallbackSource', 'https://api.nuget.org/v3/index.json',
-        '-OutputDirectory', 'C:\\cibw\\python',
+        "-Version",
+        version,
+        "-FallbackSource",
+        "https://api.nuget.org/v3/index.json",
+        "-OutputDirectory",
+        str(CIBW_INSTALL_PATH / "python"),
    ]


@@ -60,27 +65,23 @@ class PythonConfiguration(NamedTuple):


 def get_python_configurations(
-        build_selector: BuildSelector,
-        architectures: Set[Architecture],
+    build_selector: BuildSelector,
+    architectures: Set[Architecture],
 ) -> List[PythonConfiguration]:

-    full_python_configs = read_python_configs('windows')
+    full_python_configs = read_python_configs("windows")

    python_configurations = [PythonConfiguration(**item) for item in full_python_configs]

    map_arch = {
-        '32': Architecture.x86,
-        '64': Architecture.AMD64,
+        "32": Architecture.x86,
+        "64": Architecture.AMD64,
    }

-    # Only supported with custom compiler, since MS removed the 2008 compiler download
-    custom_compiler = os.environ.get('DISTUTILS_USE_SDK') and os.environ.get('MSSdk')
-    if not custom_compiler:
-        python_configurations = [c for c in python_configurations if not c.version.startswith('2.7')]
-
    # skip builds as required
    python_configurations = [
-        c for c in python_configurations
+        c
+        for c in python_configurations
        if build_selector(c.identifier) and map_arch[c.arch] in architectures
    ]

@@ -94,135 +95,174 @@ def extract_zip(zip_src: Path, dest: Path) -> None:

 def install_cpython(version: str, arch: str, nuget: Path) -> Path:
    nuget_args = get_nuget_args(version, arch)
-    installation_path = Path(nuget_args[-1]) / (nuget_args[0] + '.' + version) / 'tools'
-    call([nuget, 'install', *nuget_args])
+    installation_path = Path(nuget_args[-1]) / (nuget_args[0] + "." + version) / "tools"
+    call([nuget, "install", *nuget_args])
    return installation_path


 def install_pypy(version: str, arch: str, url: str) -> Path:
-    assert arch == '32'
+    assert arch == "64" and "win64" in url
    # Inside the PyPy zip file is a directory with the same name
-    zip_filename = url.rsplit('/', 1)[-1]
+    zip_filename = url.rsplit("/", 1)[-1]
    extension = ".zip"
    assert zip_filename.endswith(extension)
-    installation_path = Path('C:\\cibw') / zip_filename[:-len(extension)]
+    installation_path = CIBW_INSTALL_PATH / zip_filename[: -len(extension)]
    if not installation_path.exists():
-        pypy_zip = Path('C:\\cibw') / zip_filename
+        pypy_zip = CIBW_INSTALL_PATH / zip_filename
        download(url, pypy_zip)
        # Extract to the parent directory because the zip file still contains a directory
        extract_zip(pypy_zip, installation_path.parent)
-        pypy_exe = 'pypy3.exe' if version[0] == '3' else 'pypy.exe'
-        (installation_path / 'python.exe').symlink_to(installation_path / pypy_exe)
+        (installation_path / "python.exe").symlink_to(installation_path / "pypy3.exe")
    return installation_path


-def setup_python(python_configuration: PythonConfiguration, dependency_constraint_flags: Sequence[PathOrStr], environment: ParsedEnvironment) -> Dict[str, str]:
-    nuget = Path('C:\\cibw\\nuget.exe')
+def setup_python(
+    python_configuration: PythonConfiguration,
+    dependency_constraint_flags: Sequence[PathOrStr],
+    environment: ParsedEnvironment,
+    build_frontend: BuildFrontend,
+) -> Dict[str, str]:
+
+    nuget = CIBW_INSTALL_PATH / "nuget.exe"
    if not nuget.exists():
-        log.step('Downloading nuget...')
-        download('https://dist.nuget.org/win-x86-commandline/latest/nuget.exe', nuget)
+        log.step("Downloading nuget...")
+        download("https://dist.nuget.org/win-x86-commandline/latest/nuget.exe", nuget)

    implementation_id = python_configuration.identifier.split("-")[0]
-    log.step(f'Installing Python {implementation_id}...')
+    log.step(f"Installing Python {implementation_id}...")

-    if implementation_id.startswith('cp'):
-        installation_path = install_cpython(python_configuration.version, python_configuration.arch, nuget)
-    elif implementation_id.startswith('pp'):
+    if implementation_id.startswith("cp"):
+        installation_path = install_cpython(
+            python_configuration.version, python_configuration.arch, nuget
+        )
+    elif implementation_id.startswith("pp"):
        assert python_configuration.url is not None
-        installation_path = install_pypy(python_configuration.version, python_configuration.arch, python_configuration.url)
+        installation_path = install_pypy(
+            python_configuration.version, python_configuration.arch, python_configuration.url
+        )
    else:
        raise ValueError("Unknown Python implementation")

-    assert (installation_path / 'python.exe').exists()
+    assert (installation_path / "python.exe").exists()

-    log.step('Setting up build environment...')
+    log.step("Setting up build environment...")

    # set up PATH and environment variables for run_with_env
    env = os.environ.copy()
-    env['PYTHON_VERSION'] = python_configuration.version
-    env['PYTHON_ARCH'] = python_configuration.arch
-    env['PATH'] = os.pathsep.join([
-        str(installation_path),
-        str(installation_path / 'Scripts'),
-        env['PATH']
-    ])
-    env['PIP_DISABLE_PIP_VERSION_CHECK'] = '1'
+    env["PYTHON_VERSION"] = python_configuration.version
+    env["PYTHON_ARCH"] = python_configuration.arch
+    env["PATH"] = os.pathsep.join(
+        [str(installation_path), str(installation_path / "Scripts"), env["PATH"]]
+    )
+    env["PIP_DISABLE_PIP_VERSION_CHECK"] = "1"

    # update env with results from CIBW_ENVIRONMENT
    env = environment.as_dictionary(prev_environment=env)

    # for the logs - check we're running the right version of python
-    call(['where', 'python'], env=env)
-    call(['python', '--version'], env=env)
-    call(['python', '-c', '"import struct; print(struct.calcsize(\'P\') * 8)"'], env=env)
-    where_python = subprocess.run(['where', 'python'], env=env, universal_newlines=True, check=True, stdout=subprocess.PIPE).stdout.splitlines()[0].strip()
-    if where_python != str(installation_path / 'python.exe'):
-        print("cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it.", file=sys.stderr)
+    call(["where", "python"], env=env)
+    call(["python", "--version"], env=env)
+    call(["python", "-c", "\"import struct; print(struct.calcsize('P') * 8)\""], env=env)
+    where_python = (
+        subprocess.run(
+            ["where", "python"],
+            env=env,
+            universal_newlines=True,
+            check=True,
+            stdout=subprocess.PIPE,
+        )
+        .stdout.splitlines()[0]
+        .strip()
+    )
+    if where_python != str(installation_path / "python.exe"):
+        print(
+            "cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it.",
+            file=sys.stderr,
+        )
        sys.exit(1)

-    # make sure pip is installed
-    if not (installation_path / 'Scripts' / 'pip.exe').exists():
-        call(['python', get_pip_script, *dependency_constraint_flags], env=env, cwd="C:\\cibw")
-    assert (installation_path / 'Scripts' / 'pip.exe').exists()
-    where_pip = subprocess.run(['where', 'pip'], env=env, universal_newlines=True, check=True, stdout=subprocess.PIPE).stdout.splitlines()[0].strip()
-    if where_pip.strip() != str(installation_path / 'Scripts' / 'pip.exe'):
-        print("cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.", file=sys.stderr)
+    log.step("Installing build tools...")
+
+    # Install pip
+
+    requires_reinstall = not (installation_path / "Scripts" / "pip.exe").exists()
+    if requires_reinstall:
+        # maybe pip isn't installed at all. ensurepip resolves that.
+        call(["python", "-m", "ensurepip"], env=env, cwd=CIBW_INSTALL_PATH)
+
+    # upgrade pip to the version matching our constraints
+    # if necessary, reinstall it to ensure that it's available on PATH as 'pip.exe'
+    call(
+        [
+            "python",
+            "-m",
+            "pip",
+            "install",
+            "--force-reinstall" if requires_reinstall else "--upgrade",
+            "pip",
+            *dependency_constraint_flags,
+        ],
+        env=env,
+        cwd=CIBW_INSTALL_PATH,
+    )
+
+    assert (installation_path / "Scripts" / "pip.exe").exists()
+    where_pip = (
+        subprocess.run(
+            ["where", "pip"], env=env, universal_newlines=True, check=True, stdout=subprocess.PIPE
+        )
+        .stdout.splitlines()[0]
+        .strip()
+    )
+    if where_pip.strip() != str(installation_path / "Scripts" / "pip.exe"):
+        print(
+            "cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.",
+            file=sys.stderr,
+        )
        sys.exit(1)

-    log.step('Installing build tools...')
+    call(["pip", "--version"], env=env)

-    call(['python', '-m', 'pip', 'install', '--upgrade', 'pip', *dependency_constraint_flags], env=env)
-    call(['pip', '--version'], env=env)
-    call(['pip', 'install', '--upgrade', 'setuptools', 'wheel', *dependency_constraint_flags], env=env)
+    if build_frontend == "pip":
+        call(
+            [
+                "pip",
+                "install",
+                "--upgrade",
+                "setuptools",
+                "wheel",
+                *dependency_constraint_flags,
+            ],
+            env=env,
+        )
+    elif build_frontend == "build":
+        call(
+            ["pip", "install", "--upgrade", "build[virtualenv]", *dependency_constraint_flags],
+            env=env,
+        )
+    else:
+        assert_never(build_frontend)

    return env


-def pep_518_cp35_workaround(package_dir: Path, env: Dict[str, str]) -> None:
-    """
-    Python 3.5 PEP 518 hack (see https://github.com/pypa/pip/issues/8392#issuecomment-639563494)
-    Basically, nuget's Python is an embedded Python distribution, which is not supported by pip.
-    Before version 3.6, there was no way to disable the "embedded" behavior, including the ignoring
-    of environment variables, including the ones pip uses to setup PEP 518 builds.
-
-    The fix here is as suggested in that issue; we manually setup the PEP 518 requirements. Since we
-    are in a fresh environment (except for pinned cibuildweel dependencies), the build is already
-    mostly "isolated".
-    """
-
-    pyproject_path = package_dir / 'pyproject.toml'
-
-    if pyproject_path.exists():
-        data = toml.load(pyproject_path)
-        requirements = (
-            data['build-system'].get('requires', [])
-            if 'build-system' in data
-            else []
-        )
-
-        if requirements:
-            log.step('Performing PEP518 workaround...')
-            with tempfile.TemporaryDirectory() as d:
-                reqfile = Path(d) / "requirements.txt"
-                with reqfile.open('w') as f:
-                    for r in requirements:
-                        print(r, file=f)
-                call(['pip', 'install', '-r', reqfile], env=env)
-
-
 def build(options: BuildOptions) -> None:
-    temp_dir = Path(tempfile.mkdtemp(prefix='cibuildwheel'))
-    built_wheel_dir = temp_dir / 'built_wheel'
-    repaired_wheel_dir = temp_dir / 'repaired_wheel'
+    temp_dir = Path(tempfile.mkdtemp(prefix="cibuildwheel"))
+    built_wheel_dir = temp_dir / "built_wheel"
+    repaired_wheel_dir = temp_dir / "repaired_wheel"

    try:
        if options.before_all:
-            log.step('Running before_all...')
+            log.step("Running before_all...")
            env = options.environment.as_dictionary(prev_environment=os.environ)
-            before_all_prepared = prepare_command(options.before_all, project='.', package=options.package_dir)
+            before_all_prepared = prepare_command(
+                options.before_all, project=".", package=options.package_dir
+            )
            shell(before_all_prepared, env=env)

-        python_configurations = get_python_configurations(options.build_selector, options.architectures)
+        python_configurations = get_python_configurations(
+            options.build_selector, options.architectures
+        )

        for config in python_configurations:
            log.build_start(config.identifier)
@@ -230,100 +270,155 @@ def build(options: BuildOptions) -> None:
            dependency_constraint_flags: Sequence[PathOrStr] = []
            if options.dependency_constraints:
                dependency_constraint_flags = [
-                    '-c', options.dependency_constraints.get_for_python_version(config.version)
+                    "-c",
+                    options.dependency_constraints.get_for_python_version(config.version),
                ]

            # install Python
-            env = setup_python(config, dependency_constraint_flags, options.environment)
+            env = setup_python(
+                config,
+                dependency_constraint_flags,
+                options.environment,
+                options.build_frontend,
+            )

            # run the before_build command
            if options.before_build:
-                log.step('Running before_build...')
-                before_build_prepared = prepare_command(options.before_build, project='.', package=options.package_dir)
+                log.step("Running before_build...")
+                before_build_prepared = prepare_command(
+                    options.before_build, project=".", package=options.package_dir
+                )
                shell(before_build_prepared, env=env)

-            # activate the PEP 518 patch if on Windows Python 3.5
-            # (will only have an effect if PEP 517 builds are used):
-            if config.version.startswith('3.5'):
-                pep_518_cp35_workaround(options.package_dir, env)
-
-            log.step('Building wheel...')
+            log.step("Building wheel...")
            if built_wheel_dir.exists():
                shutil.rmtree(built_wheel_dir)
            built_wheel_dir.mkdir(parents=True)
-            # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
-            # see https://github.com/joerick/cibuildwheel/pull/369
-            call([
-                'pip', 'wheel',
-                options.package_dir.resolve(),
-                '-w', built_wheel_dir,
-                '--no-deps',
-                *get_build_verbosity_extra_flags(options.build_verbosity)
-            ], env=env)

-            built_wheel = next(built_wheel_dir.glob('*.whl'))
+            verbosity_flags = get_build_verbosity_extra_flags(options.build_verbosity)
+
+            if options.build_frontend == "pip":
+                # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
+                # see https://github.com/pypa/cibuildwheel/pull/369
+                call(
+                    [
+                        "python",
+                        "-m",
+                        "pip",
+                        "wheel",
+                        options.package_dir.resolve(),
+                        f"--wheel-dir={built_wheel_dir}",
+                        "--no-deps",
+                        *get_build_verbosity_extra_flags(options.build_verbosity),
+                    ],
+                    env=env,
+                )
+            elif options.build_frontend == "build":
+                config_setting = " ".join(verbosity_flags)
+                build_env = env.copy()
+                if options.dependency_constraints:
+                    constraints_path = options.dependency_constraints.get_for_python_version(
+                        config.version
+                    )
+                    # Bug in pip <= 21.1.3 - we can't have a space in the
+                    # constraints file, and pip doesn't support drive letters
+                    # in uhi.  After probably pip 21.2, we can use uri. For
+                    # now, use a temporary file.
+                    if " " in str(constraints_path):
+                        tmp_file = tempfile.NamedTemporaryFile(
+                            "w", suffix="constraints.txt", delete=False, dir=CIBW_INSTALL_PATH
+                        )
+                        with tmp_file as new_constraints_file, open(constraints_path) as f:
+                            new_constraints_file.write(f.read())
+                            constraints_path = Path(new_constraints_file.name)
+
+                    build_env["PIP_CONSTRAINT"] = str(constraints_path)
+                    build_env["VIRTUALENV_PIP"] = get_pip_version(env)
+                    call(
+                        [
+                            "python",
+                            "-m",
+                            "build",
+                            options.package_dir,
+                            "--wheel",
+                            f"--outdir={built_wheel_dir}",
+                            f"--config-setting={config_setting}",
+                        ],
+                        env=build_env,
+                    )
+            else:
+                assert_never(options.build_frontend)
+
+            built_wheel = next(built_wheel_dir.glob("*.whl"))

            # repair the wheel
            if repaired_wheel_dir.exists():
                shutil.rmtree(repaired_wheel_dir)
            repaired_wheel_dir.mkdir(parents=True)

-            if built_wheel.name.endswith('none-any.whl'):
+            if built_wheel.name.endswith("none-any.whl"):
                raise NonPlatformWheelError()

            if options.repair_command:
-                log.step('Repairing wheel...')
-                repair_command_prepared = prepare_command(options.repair_command, wheel=built_wheel, dest_dir=repaired_wheel_dir)
+                log.step("Repairing wheel...")
+                repair_command_prepared = prepare_command(
+                    options.repair_command, wheel=built_wheel, dest_dir=repaired_wheel_dir
+                )
                shell(repair_command_prepared, env=env)
            else:
                shutil.move(str(built_wheel), repaired_wheel_dir)

-            repaired_wheel = next(repaired_wheel_dir.glob('*.whl'))
+            repaired_wheel = next(repaired_wheel_dir.glob("*.whl"))

            if options.test_command and options.test_selector(config.identifier):
-                log.step('Testing wheel...')
+                log.step("Testing wheel...")
                # set up a virtual environment to install and test from, to make sure
                # there are no dependencies that were pulled in at build time.
-                call(['pip', 'install', 'virtualenv', *dependency_constraint_flags], env=env)
+                call(["pip", "install", "virtualenv", *dependency_constraint_flags], env=env)
                venv_dir = Path(tempfile.mkdtemp())

                # Use --no-download to ensure determinism by using seed libraries
                # built into virtualenv
-                call(['python', '-m', 'virtualenv', '--no-download', venv_dir], env=env)
+                call(["python", "-m", "virtualenv", "--no-download", venv_dir], env=env)

                virtualenv_env = env.copy()
-                virtualenv_env['PATH'] = os.pathsep.join([
-                    str(venv_dir / 'Scripts'),
-                    virtualenv_env['PATH'],
-                ])
+                virtualenv_env["PATH"] = os.pathsep.join(
+                    [
+                        str(venv_dir / "Scripts"),
+                        virtualenv_env["PATH"],
+                    ]
+                )

                # check that we are using the Python from the virtual environment
-                call(['where', 'python'], env=virtualenv_env)
+                call(["where", "python"], env=virtualenv_env)

                if options.before_test:
                    before_test_prepared = prepare_command(
                        options.before_test,
-                        project='.',
+                        project=".",
                        package=options.package_dir,
                    )
                    shell(before_test_prepared, env=virtualenv_env)

                # install the wheel
-                call(['pip', 'install', str(repaired_wheel) + options.test_extras], env=virtualenv_env)
+                call(
+                    ["pip", "install", str(repaired_wheel) + options.test_extras],
+                    env=virtualenv_env,
+                )

                # test the wheel
                if options.test_requires:
-                    call(['pip', 'install'] + options.test_requires, env=virtualenv_env)
+                    call(["pip", "install"] + options.test_requires, env=virtualenv_env)

                # run the tests from c:\, with an absolute path in the command
                # (this ensures that Python runs the tests against the installed wheel
                # and not the repo code)
                test_command_prepared = prepare_command(
                    options.test_command,
-                    project=Path('.').resolve(),
+                    project=Path(".").resolve(),
                    package=options.package_dir.resolve(),
                )
-                shell(test_command_prepared, cwd='c:\\', env=virtualenv_env)
+                shell(test_command_prepared, cwd="c:\\", env=virtualenv_env)

                # clean up
                shutil.rmtree(venv_dir)
@@ -332,5 +427,7 @@ def build(options: BuildOptions) -> None:
            shutil.move(str(repaired_wheel), options.output_dir)
            log.build_end()
    except subprocess.CalledProcessError as error:
-        log.step_end_with_error(f'Command {error.cmd} failed with code {error.returncode}. {error.stdout}')
+        log.step_end_with_error(
+            f"Command {error.cmd} failed with code {error.returncode}. {error.stdout}"
+        )
        sys.exit(1)
@@ -8,6 +8,8 @@ If you have an idea for a modification or feature, it's probably best to raise a

 `cibuildwheel` is indie open source. We're not paid to work on this.

+Everyone contributing to the cibuildwheel project is expected to follow the [PSF Code of Conduct](https://github.com/pypa/.github/blob/main/CODE_OF_CONDUCT.md).
+
 Design Goals
 ------------

@@ -27,16 +29,37 @@ cibuildwheel doesn't really do anything itself - it's always deferring to other

 We're not responsible for errors in those tools, for fixing errors/crashes there. But cibuildwheel's job is providing users with an 'integrated' user experience across those tools. We provide an abstraction. The user says 'build me some wheels', not 'open the docker container, build a wheel with pip, fix up the symbols with auditwheel' etc.  However, errors have a habit of breaking abstractions. And this is where users get confused, because the mechanism of cibuildwheel is laid bare, and they must understand a little bit how it works to debug.

-So, if we can, I'd like to improve the experience on errors as well. In [this](https://github.com/joerick/cibuildwheel/issues/139) case, it takes a bit of knowledge to understand that the Linux builds are happening in a different OS via Docker, that the linked symbols won't match, that auditwheel will fail because of this. A problem with how the tools fit together, instead of the tools themselves.
+So, if we can, I'd like to improve the experience on errors as well. In [this](https://github.com/pypa/cibuildwheel/issues/139) case, it takes a bit of knowledge to understand that the Linux builds are happening in a different OS via Docker, that the linked symbols won't match, that auditwheel will fail because of this. A problem with how the tools fit together, instead of the tools themselves.

 Maintainer notes
 ----------------

+### Nox support
+
+Most developer tasks have a nox interface. This allows you to very simply run tasks without worrying about setting up a development environment (as shown below). This is a slower than setting up a development environment and reusing it, but has the (important) benefit of being highly reproducible; an earlier run does not affect a current run, or anything else on your machine.
+
+Install [nox](https://nox.thea.codes); homebrew is recommend on macOS, otherwise, pipx is a great choice - in fact, you can use `pipx run nox` and avoid installing completely.
+
+You can see a list of sessions by typing `nox -l`; here are a few common ones:
+
+```console
+nox -s lint          # Run the linters (default)
+nox -s tests         # Run the tests   (default)
+nox -s docs -- serve # Build and serve the documentation
+nox -s build         # Make SDist and wheel
+```
+
+More advanced users can run the update scripts. `update_pins` should work directly, but `update_constraints` needs all versions of Python installed. If you don't want to do that locally, a fast way to run it to use docker to run nox:
+
+```console
+docker run --rm -itv $PWD:/src -w /src quay.io/pypa/manylinux_2_24_x86_64:latest pipx run nox -s update_constraints
+```
+
 ### Local testing

 You should run:

-```python
+```console
 python3 -m venv venv
 . venv/bin/activate
 pip install -e .[dev]
@@ -71,8 +94,6 @@ This has been moved to using docker, so you only need the following instructions
 The dependency update script in the next section requires multiple python versions installed. One way to do this is to use `pyenv`:

 ```bash
-pyenv install 2.7.18
-pyenv install 3.5.9
 pyenv install 3.6.11
 pyenv install 3.7.8
 # Optionally add 3.8 and make it the local version;
@@ -82,9 +103,6 @@ pyenv install 3.7.8
 Then, you need to make the required virtual environments:

 ```bash
-$(pyenv prefix 2.7.18)/bin/python -m pip install virtualenv
-$(pyenv prefix 2.7.18)/bin/python -m virtualenv env27
-$(pyenv prefix 3.5.9)/bin/python -m venv env35
 $(pyenv prefix 3.6.11)/bin/python -m venv env36
 $(pyenv prefix 3.7.8)/bin/python -m venv env37
 ```
@@ -118,4 +136,4 @@ twine upload dist/*
 git push && git push --tags
 ```

-Then head to https://github.com/joerick/cibuildwheel/releases and create a GitHub release from the new tag, pasting in the changelog entry.
+Then head to https://github.com/pypa/cibuildwheel/releases and create a GitHub release from the new tag, pasting in the changelog entry.
@@ -5,10 +5,6 @@ title: Modern C++ standards
 Building Python wheels with modern C++ standards (C++11 and later) requires a few tricks.


-## Python 2.7 and C++17
-
-The Python 2.7 header files use the `register` keyword, which is [reserved and unused from C+17 onwards](https://en.cppreference.com/w/cpp/keyword/register). Compiling a wheel for Python 2.7 with the C++17 standard is still possible to allow usage of `register` using proper flag `-Wno-register` for gcc/clang and `/wd5033` for MSVC.
-
 ## manylinux1 and C++14
 The default `manylinux1` image (based on CentOS 5) contains a version of GCC and libstdc++ that only supports C++11 and earlier standards. There are however ways to compile wheels with the C++14 standard (and later): https://github.com/pypa/manylinux/issues/118

@@ -27,45 +23,3 @@ To get C++17 support, Xcode 9.3+ is needed, requiring at least macOS 10.13 on th
 However, if only C++17 compiler and standard template library (STL) features are used (not needing a C++17 runtime) it might be possible to set `MACOSX_DEPLOYMENT_TARGET` to a lower value, such as `"10.9"`. To find out if this is the case, try compiling and running with a lower `MACOSX_DEPLOYMENT_TARGET`: if C++17 features are used that require a more recent deployment target, building the wheel should fail.

 For more details see https://en.cppreference.com/w/cpp/compiler_support, https://en.wikipedia.org/wiki/Xcode, and https://xcodereleases.com/: Xcode 10 needs macOS 10.13 and Xcode 11 needs macOS 10.14.
-
-## Windows and Python 2.7
-
-In previous years, Microsoft distributed a compiler toolchain called 'Visual C++ for Python 2.7', which was a distribution of MSVC 2008 that was created to make it easier to build Python 2.7 extensions on Windows, because it was fully compatible with the toolchain that built Python 2.7.
-
-This toolchain does not support modern C++ standards (i.e., C++11 and later). And it is hard to find this toolchain these days, since Microsoft removed the download for the required Visual Studio 2008 needed to build a native extension in April, 2021. So, by default, cibuildwheel does not attempt to build Python 2.7 extensions on Windows.
-
-There is an optional workaround, though: the pybind11 project argues and shows that it is [possible to compile Python 2.7 extension with a newer compiler](https://pybind11.readthedocs.io/en/stable/faq.html#working-with-ancient-visual-studio-2008-builds-on-windows) and has an example project showing how to do this: https://github.com/pybind/python_example. The main catch is that a user might need to install [a newer "Microsoft Visual C++ Redistributable"](https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads), since the newer C++ standard library's binaries are not included by default with the Python 2.7 installation.
-
-Forcing `distutils` or `setuptools` to use a more recent version of MSVC that supports modern C++ can be done in the following way:
-
-1. Set the environment variables `DISTUTILS_USE_SDK=1` and `MSSdk=1`. These two environment variables will tell `distutils`/`setuptools` to not search and set up a build environment that uses Visual C++ for Python 2.7 (aka. MSVC 9).
-2. Set up the build Visual Studio build environment you want to use, making sure that e.g. `PATH` contains `cl`, `link`, etc.
-    - Usually, this can be done through `vcvarsall.bat x86` or `vcvarsall.bat x64`. The exact location of this file depends on the installation, but the default path for VS 2019 Community (e.g. used in AppVeyor's `Visual Studio 2019` image) is `C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat`. **Note**: `vcvarsall.bat` changes the environment variables, so this cannot be run in a subprocess/subshell and consequently running `vsvarsall.bat` in `CIBW_BEFORE_BUILD` does not have any effect.
-    - In Azure Pipelines, [a `VSBuild` task is available](https://docs.microsoft.com/en-us/azure/devops/pipelines/tasks/build/visual-studio-build)
-    - In GitHub Actions, the default shell is powershell, so you'll need to use `shell: cmd` to source a `.bat` file, and the directory is `"C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvarsall.bat"`. Or you can use an action, such as the [`ilammy/msvc-dev-cmd@v1`](https://github.com/ilammy/msvc-dev-cmd) action to setup the environment (see example below).
-3. Next, call `cibuildwheel`. Unfortunately, MSVC has separate toolchains for compiling 32-bit and 64-bit, so you will need to run `cibuildwheel` twice: once with `CIBW_BUILD=*-win32` after setting up the `x86` build environment, and once with `CIBW_BUILD=*-win_amd64` in a `x64` environment (see previous step).
-
-
-**GitHub Action example with ilammy/msvc-dev-cmd**:
-
-```yaml
-  - uses: ilammy/msvc-dev-cmd@v1
-
-  - name: Build 64-bit wheel
-    run: python -m cibuildwheel --output-dir wheelhouse
-    env:
-      CIBW_BUILD: cp27-win_amd64
-      DISTUTILS_USE_SDK: 1
-      MSSdk: 1
-
-  - uses: ilammy/msvc-dev-cmd@v1
-    with:
-      arch: x86
-
-  - name: Build 32-bit wheel
-    run: python -m cibuildwheel --output-dir wheelhouse
-    env:
-      CIBW_BUILD: cp27-win32
-      DISTUTILS_USE_SDK: 1
-      MSSdk: 1
-```
@@ -324,3 +324,42 @@
  gh: pallets/markupsafe
  ci: [github]
  os: [apple, linux, windows]
+
+- name: SiPM
+  gh: EdoPro98/SimSiPM
+  ci: [github]
+  os: [apple, linux]
+  notes: High performance library for SiPM detectors simulation using C++17, OpenMP and AVX2 intrinsics.
+
+- name: CorrectionLib
+  gh: cms-nanoAOD/correctionlib
+  ci: [github]
+  os: [apple, linux]
+  notes: Structured JSON powered correction library for HEP, designed for the CMS experiment at CERN.
+
+- name: GSD
+  gh: glotzerlab/gsd
+  ci: [github]
+  os: [apple, linux, windows]
+  notes: Cython and NumPy project with 64-bit wheels.
+
+- name: PyGLM
+  gh: Zuzu-Typ/PyGLM
+  ci: [github]
+  os: [apple, linux, windows]
+
+- name: iDynTree
+  gh: robotology/idyntree
+  ci: [github]
+  os: [linux]
+  notes: Uses manylinux_2_24
+
+- name: H3-py
+  gh: uber/h3-py
+  ci: [github]
+  os: [apple, linux, windows]
+
+- name: DeepForest
+  gh: LAMDA-NJU/Deep-Forest
+  ci: [github]
+  os: [apple, linux, windows]
@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" role="img" viewBox="0 0 24 24" width="16px" fill="#606060"><title>Azure Pipelines icon</title><path d="M1.8 18H0v6h6v-1.8H1.8zM23 0h-8.93a2 2 0 0 0-1.67.89L9 5.99H1a1 1 0 0 0-1 1v5.5l3.5 3.61 1.2-1.29 1.5 1.5L5 17.53l1.48 1.48 1.22-1.22 1.5 1.51L8 20.5l3.5 3.5H17a1 1 0 0 0 1-1v-8l5.11-3.4A2 2 0 0 0 24 9.92V1a1 1 0 0 0-1-1zm-5 9a3 3 0 1 1 0-6 3 3 0 0 1 0 6z"/></svg>
+<svg xmlns="http://www.w3.org/2000/svg" role="img" viewBox="0 0 24 24" width="16px" fill="#606060"><title>Azure Pipelines icon</title><path d="M1.7997 22.1998h4.2001V24H.0004v-6.0002h1.7993v4.2zM12.6229 9.8975l-7.6353 7.6353 1.4792 1.4792 7.6345-7.6362-1.4784-1.4783zM4.365 15.1793l-.391-.3908c-.5042-.5042-.5828-1.3004-.1869-1.8934l4.6036-6.8958H.9979c-.5513.0014-.9975.4487-.9975 1v5.5002l3.5021 3.6036.8625-.9238zM23.9996.9999v8.9306a2 2 0 0 1-.8893 1.6632l-12.2834 8.2005a.9999.9999 0 0 1-1.2622-.1246L8.04 18.1457c.3313-.3313 6.4656-6.4672 6.7684-6.7698l-2.1855-2.1855L5.8533 15.96l-1.5258-1.525a1.0001 1.0001 0 0 1-.1246-1.2623L12.4034.8893A2 2 0 0 1 14.0666 0h8.9331c.5522 0 .9999.4477.9999.9999zm-2.9997 5.0003c0-1.6567-1.343-2.9997-2.9997-2.9997s-2.9997 1.343-2.9997 2.9997 1.343 2.9997 2.9997 2.9997 2.9997-1.343 2.9997-2.9997zM10.272 20.4625c-.4008 0-.7776-.156-1.0609-.4392l-.368-.3679-.8435.8417 3.4996 3.4996h5.5003c.5522 0 .9999-.4477.9999-.9999v-7.3899L11.1045 20.21a1.4944 1.4944 0 0 1-.8325.2525z"/></svg>
@@ -33,4 +33,4 @@ Obviously, manual steps are for chumps, so we can automate this a little by usin

 If you don't need much control over the release of a package, you can set up cibuildwheel to deliver the wheels straight to PyPI. This doesn't require anycloud storage to work - you just need to bump the version and tag it.

-[`examples/travis-ci-deploy.yml`](https://github.com/joerick/cibuildwheel/blob/master/examples/travis-ci-deploy.yml) and [`examples/github-deploy.yml`](https://github.com/joerick/cibuildwheel/blob/master/examples/github-deploy.yml) are example configurations that automatically upload wheels to PyPI. Also check out [this example repo](https://github.com/joerick/cibuildwheel-autopypi-example) for more detailed instructions on how to set this up.
+[`examples/travis-ci-deploy.yml`](https://github.com/pypa/cibuildwheel/blob/main/examples/travis-ci-deploy.yml) and [`examples/github-deploy.yml`](https://github.com/pypa/cibuildwheel/blob/main/examples/github-deploy.yml) are example configurations that automatically upload wheels to PyPI. Also check out [this example repo](https://github.com/pypa/cibuildwheel-autopypi-example) for more detailed instructions on how to set this up.
@@ -1,6 +1,10 @@

 /* Global styles */

+body {
+    overflow-wrap: break-word;
+}
+
 p {
    margin-bottom: 12px;
    line-height: 26px;
@@ -20,9 +24,9 @@ code, pre, tt {
    font-family: SFMono-Regular, Consolas, Liberation Mono, Menlo, monospace;
 }

-.hljs {
-    padding: 1em;
-    background-color: #f6f8fa;
+pre code, pre code.hljs {
+  padding: 1em;
+  background-color: #f6f8fa;
 }

 h1, h2, h3, h4, h5, h6 {
@@ -112,7 +116,21 @@ h1, h2, h3, h4, h5, h6 {
  background-color: white;
  display: flex;
  justify-content: flex-start;
-  border-bottom: 2px solid #ccc;
+  overflow-x: auto;
+  overflow-y: hidden;
+  position: relative;
+}
+.tabs-header::before {
+  position: absolute;
+  content: "";
+  bottom: 0;
+  left: 0;
+  right: 0;
+  height: 2px;
+  background: #ccc;
+}
+.tabs-header > * {
+  position: relative;
 }

 /* Style the buttons that are used to open the tab content */
@@ -126,15 +144,13 @@ h1, h2, h3, h4, h5, h6 {
  font-size: 0.9em;
  font-weight: 600;
  padding: 8px 16px;
-  border-bottom: 2px solid transparent;
-
-  /* put the border on top of the parent border */
-  margin-bottom: -2px;
+  border-bottom: 2px solid #ccc;
 }

 .tabs-header button:focus-visible {
  /* preserve an outline for accesibility purposes */
  outline: 1px solid currentColor;
+  outline-offset: -1px;
 }

 /* Change background color of buttons on hover */
@@ -153,4 +169,53 @@ h1, h2, h3, h4, h5, h6 {
  background-color: #f1f6fa;
  padding: 1px 1em;
  padding-top: 0.8em;
+
+  /* don't collapse inner margins */
+  overflow-y: hidden;
+}
+
+/* Examples tabs styling */
+
+.tabs.examples .tabs-header {
+  justify-content: flex-end;
+  background-color: transparent;
+  border-bottom-style: none;
+  padding: 0;
+}
+.tabs.examples .tabs-header::before {
+  height: 0;
+}
+.tabs.examples .tabs-header button {
+  padding: 6px 12px;
+  border-bottom: none;
+  color: rgba(0, 0, 0, 0.3);
+  font-size: 0.8em;
+  border-top-left-radius: 4px;
+  border-top-right-radius: 4px;
+}
+.tabs-header button:hover {
+  background-color: unset;
+}
+
+.tabs.examples .tabs-header button.active {
+  border-bottom-style: none;
+  background: #f6f8fa;
+  color: inherit;
+}
+.tabs.examples .tabs-content {
+  padding: 0;
+  background-color: transparent;
+  background-color: #f6f8fa;
+}
+.tabs.examples .tabs-content .tab > * {
+  padding-left: 0.8em;
+  padding-right: 0.8em;
+}
+.tabs.examples .tabs-content .tab > pre {
+  padding-left: 0;
+  padding-right: 0;
+  margin-bottom: 0.5em;
+}
+.tabs.examples pre:first-child {
+  margin-top: 0;
 }
@@ -20,6 +20,17 @@ while (true) {
  tabContainer.insertBefore(firstTab);
  tabContainer.append(headerContainer, contentContainer)

+  // add extra classes from the first tab to the container
+  const classes = Array.from(firstTab[0].classList)
+
+  for (let i = 0; i < classes.length; i++) {
+    const element = classes[i];
+    if (element == 'tab' || element == 'admonition') {
+      continue
+    }
+    tabContainer.addClass(element)
+  }
+
  const selectTab = function (index) {
    headerContainer.children().removeClass('active')
    headerContainer.children().eq(index).addClass('active')
@@ -12,7 +12,11 @@ If your wheel didn't compile, check the list below for some debugging tips.

 - Windows: missing C feature. The Windows C compiler doesn't support C language features invented after 1990, so you'll have to backport your C code to C90. For me, this mostly involved putting my variable declarations at the top of the function like an animal.

- MacOS: calling cibuildwheel from a python3 script and getting a `ModuleNotFoundError`? Due to a (fixed) [bug](https://bugs.python.org/issue22490) in CPython, you'll need to [unset the `__PYVENV_LAUNCHER__` variable](https://github.com/joerick/cibuildwheel/issues/133#issuecomment-478288597) before activating a venv.
+- MacOS: calling cibuildwheel from a python3 script and getting a `ModuleNotFoundError`? Due to a (fixed) [bug](https://bugs.python.org/issue22490) in CPython, you'll need to [unset the `__PYVENV_LAUNCHER__` variable](https://github.com/pypa/cibuildwheel/issues/133#issuecomment-478288597) before activating a venv.
+
+### Building Python 2.7 / PyPy2 wheels
+
+See the [cibuildwheel verison 1 docs](https://cibuildwheel.readthedocs.io/en/1.x/) for information about building Python 2.7 or PyPy2 wheels. There are lots of tricks and workaround there that are no longer required for Python 3 in cibuildwheel 2.

 ### Linux builds on Docker

@@ -80,7 +84,7 @@ by default, and require opt-in by setting `CIBW_ARCHS_MACOS`.
 !!! note
    Your runner needs Xcode Command Line Tools 12.2 or later to build `universal2` or `arm64`.

-    So far, only CPython 3.9 supports `universal2` and `arm64` wheels.
+    Only CPython 3.8 and newer support `universal2` and `arm64` wheels.

 Here's an example GitHub Actions workflow with a job that builds for Apple Silicon:

@@ -136,35 +140,6 @@ Here's an example GitHub Actions workflow with a job that builds for Apple Silic
 {% include "../examples/github-apple-silicon.yml" %}
 ```

-### Windows and Python 2.7
-
-Building 2.7 extensions on Windows is difficult, because the VS 2008 compiler that was used for the original Python compilation was discontinued in 2018, and has since been removed from Microsoft's downloads. Most people choose to not build Windows 2.7 wheels, or to override the compiler to something more modern.
-
-To override, you need to have a modern compiler toolchain activated, and set `DISTUTILS_USE_SDK=1` and `MSSdk=1`. For example, on GitHub Actions, you would add these steps:
-
-```yaml
-    - name: Prepare compiler environment for Windows
-      if: runner.os == 'Windows'
-      uses: ilammy/msvc-dev-cmd@v1
-      with:
-        arch: x64
-
-    - name: Set Windows environment variables
-      if: runner.os == 'Windows'
-      shell: bash
-      run: |
-        echo "DISTUTILS_USE_SDK=1" >> $GITHUB_ENV
-        echo "MSSdk=1" >> $GITHUB_ENV
-
-    # invoke cibuildwheel...
-```
-
-cibuildwheel will not try to build 2.7 on Windows unless it detects that the above two variables are set. Note that changing to a more modern compiler will mean your wheel picks up a runtime dependency to a different [Visual C++ Redistributable][]. You also need to be [a bit careful][] in designing your extension; some major binding tools like pybind11 do this for you.
-
-More on setting a custom Windows toolchain in our docs on modern C++ standards [here](cpp_standards.md#windows-and-python-27).
-
-[Visual C++ Redistributable]: https://support.microsoft.com/en-us/topic/the-latest-supported-visual-c-downloads-2647da03-1eea-4433-9aff-95f26a218cc0
-[a bit careful]: https://pybind11.readthedocs.io/en/stable/faq.html#working-with-ancient-visual-studio-2008-builds-on-windows

 ### Building packages with optional C extensions

@@ -206,9 +181,9 @@ python3 -m twine upload wheelhouse/*.whl

 ### 'ImportError: DLL load failed: The specific module could not be found' error on Windows

-Visual Studio and MSVC link the compiled binary wheels to the Microsoft Visual C++ Runtime. Normally, these are included with Python, but when compiling with a newer version of Visual Studio, it is possible users will run into problems on systems that do not have these runtime libraries installed. The solution is to ask users to download the corresponding Visual C++ Redistributable from the [Microsoft website](https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads) and install it. Since a Python installation normally includes these VC++ Redistributable files for [the version of the MSVC compiler used to compile Python](https://wiki.python.org/moin/WindowsCompilers), this is typically only a problem when compiling a Python 2.7 C extension with a newer compiler, e.g. to support a modern C++ standard (see [the section on modern C++ standards for Python 2.7](cpp_standards.md#windows-and-python-27) for more details).
+Visual Studio and MSVC link the compiled binary wheels to the Microsoft Visual C++ Runtime. Normally, these are included with Python, but when compiling with a newer version of Visual Studio, it is possible users will run into problems on systems that do not have these runtime libraries installed. The solution is to ask users to download the corresponding Visual C++ Redistributable from the [Microsoft website](https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads) and install it. Since a Python installation normally includes these VC++ Redistributable files for [the version of the MSVC compiler used to compile Python](https://wiki.python.org/moin/WindowsCompilers), this is typically only a problem when compiling a Python C extension with a newer compiler.

-Additionally, Visual Studio 2019 started linking to an even newer DLL, `VCRUNTIME140_1.dll`, besides the `VCRUNTIME140.dll` that is included with recent Python versions (starting from Python 3.5; see [here](https://wiki.python.org/moin/WindowsCompilers) for more details on the corresponding Visual Studio & MSVC versions used to compile the different Python versions). To avoid this extra dependency on `VCRUNTIME140_1.dll`, the [`/d2FH4-` flag](https://devblogs.microsoft.com/cppblog/making-cpp-exception-handling-smaller-x64/) can be added to the MSVC invocations (check out [this issue](https://github.com/joerick/cibuildwheel/issues/423) for details and references).
+Additionally, Visual Studio 2019 started linking to an even newer DLL, `VCRUNTIME140_1.dll`, besides the `VCRUNTIME140.dll` that is included with recent Python versions (starting from Python 3.5; see [here](https://wiki.python.org/moin/WindowsCompilers) for more details on the corresponding Visual Studio & MSVC versions used to compile the different Python versions). To avoid this extra dependency on `VCRUNTIME140_1.dll`, the [`/d2FH4-` flag](https://devblogs.microsoft.com/cppblog/making-cpp-exception-handling-smaller-x64/) can be added to the MSVC invocations (check out [this issue](https://github.com/pypa/cibuildwheel/issues/423) for details and references).

 To add the `/d2FH4-` flag to a standard `setup.py` using `setuptools`, the `extra_compile_args` option can be used:

@@ -235,12 +210,12 @@ There are two suggested methods for keeping cibuildwheel up to date that instead
 If you use GitHub Actions for builds, you can use cibuildwheel as an action:

 ```yaml
-uses: joerick/cibuildwheel@v1.10.1
+uses: pypa/cibuildwheel@v2.0.0b1
 ```

 This is a composite step that just runs cibuildwheel using pipx. You can set command-line options as `with:` parameters, and use `env:` as normal.

-Then, your `dependabot.yml` file could look like this:
+Then, your `.github/dependabot.yml` file could look like this:

 ```yaml
 version: 2
@@ -261,10 +236,10 @@ The second option, and the only one that supports other CI systems, is using a `

 ```bash
 # requirements-cibw.txt
-cibuildwheel==1.10.1
+cibuildwheel==2.0.0b1
 ```

-Then your install step would have `python -m pip install -r requirements-cibw.txt` in it. Your `dependabot.yml` file could look like this:
+Then your install step would have `python -m pip install -r requirements-cibw.txt` in it. Your `.github/dependabot.yml` file could look like this:

 ```yaml
 version: 2
@@ -0,0 +1,13 @@
+import subprocess
+from typing import Any
+
+# Requires Python 3.7+
+
+
+def define_env(env: Any) -> None:
+    "Hook function for mkdocs-macros"
+
+    @env.macro
+    def subprocess_run(*args: str) -> str:
+        "Run a subprocess and return the stdout"
+        return subprocess.run(args, check=True, capture_output=True, text=True).stdout
@@ -46,7 +46,7 @@ To build Linux, Mac, and Windows wheels using GitHub Actions, create a `.github/
          - uses: actions/checkout@v2

          - name: Build wheels
-            run: pipx run cibuildwheel==1.10.1
+            run: pipx run cibuildwheel==2.0.0b1

          - uses: actions/upload-artifact@v2
            with:
@@ -81,7 +81,7 @@ To build Linux, Mac, and Windows wheels using GitHub Actions, create a `.github/
          - uses: actions/setup-python@v2

          - name: Install cibuildwheel
-            run: python -m pip install cibuildwheel==1.10.1
+            run: python -m pip install cibuildwheel==2.0.0b1

          - name: Build wheels
            run: python -m cibuildwheel --output-dir wheelhouse
@@ -96,7 +96,7 @@ Commit this file, and push to GitHub - either to your default branch, or to a PR

 For more info on this file, check out the [docs](https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions).

-[`examples/github-deploy.yml`](https://github.com/joerick/cibuildwheel/blob/master/examples/github-deploy.yml) extends this minimal example with a demonstration of how to automatically upload the built wheels to PyPI.
+[`examples/github-deploy.yml`](https://github.com/pypa/cibuildwheel/blob/main/examples/github-deploy.yml) extends this minimal example with a demonstration of how to automatically upload the built wheels to PyPI.


 # Azure Pipelines [linux/mac/windows] {: #azure-pipelines}
@@ -109,16 +109,13 @@ To build Linux, Mac, and Windows wheels on Azure Pipelines, create a `azure-pipe
 {% include "../examples/azure-pipelines-minimal.yml" %}
 ```

-!!! note
-    To support Python 3.5 on Windows, make sure to specify the use of `{vmImage: 'vs2017-win2016'}` on Windows, to ensure the required toolchain is available.
-
 Commit this file, enable building of your repo on Azure Pipelines, and push.

 Wheels will be stored for you and available through the Pipelines interface. For more info on this file, check out the [docs](https://docs.microsoft.com/en-us/azure/devops/pipelines/yaml-schema).

-# Travis CI [linux/mac/windows] {: #travis-ci}
+# Travis CI [linux/windows] {: #travis-ci}

-To build Linux, Mac, and Windows wheels on Travis CI, create a `.travis.yml` file in your repo.
+To build Linux and Windows wheels on Travis CI, create a `.travis.yml` file in your repo.

 > .travis.yml

@@ -126,13 +123,11 @@ To build Linux, Mac, and Windows wheels on Travis CI, create a `.travis.yml` fil
 {% include "../examples/travis-ci-minimal.yml" %}
 ```

-Note that building Windows Python 2.7 wheels on Travis is unsupported unless using a newer compiler [via a workaround](cpp_standards.md).
-
 Commit this file, enable building of your repo on Travis CI, and push.

 Then setup a deployment method by following the [Travis CI deployment docs](https://docs.travis-ci.com/user/deployment/), or see [Delivering to PyPI](deliver-to-pypi.md). For more info on `.travis.yml`, check out the [docs](https://docs.travis-ci.com/).

-[`examples/travis-ci-deploy.yml`](https://github.com/joerick/cibuildwheel/blob/master/examples/travis-ci-deploy.yml) extends this minimal example with a demonstration of how to automatically upload the built wheels to PyPI.
+[`examples/travis-ci-deploy.yml`](https://github.com/pypa/cibuildwheel/blob/main/examples/travis-ci-deploy.yml) extends this minimal example with a demonstration of how to automatically upload the built wheels to PyPI.

 # AppVeyor [linux/mac/windows] {: #appveyor}

@@ -12,7 +12,7 @@ stack: python 3.7
 init:
 - cmd: set PATH=C:\Python37;C:\Python37\Scripts;%PATH%

-install: python -m pip install cibuildwheel==1.10.1
+install: python -m pip install cibuildwheel==2.0.0b1

 build_script: python -m cibuildwheel --output-dir wheelhouse

@@ -6,7 +6,7 @@ jobs:
    - bash: |
        set -o errexit
        python3 -m pip install --upgrade pip
-        pip3 install cibuildwheel==1.10.1
+        pip3 install cibuildwheel==2.0.0b1
      displayName: Install dependencies
    - bash: cibuildwheel --output-dir wheelhouse .
      displayName: Build wheels
@@ -20,7 +20,7 @@ jobs:
    - bash: |
        set -o errexit
        python3 -m pip install --upgrade pip
-        python3 -m pip install cibuildwheel==1.10.1
+        python3 -m pip install cibuildwheel==2.0.0b1
      displayName: Install dependencies
    - bash: cibuildwheel --output-dir wheelhouse .
      displayName: Build wheels
@@ -34,7 +34,7 @@ jobs:
    - bash: |
        set -o errexit
        python -m pip install --upgrade pip
-        pip install cibuildwheel==1.10.1
+        pip install cibuildwheel==2.0.0b1
      displayName: Install dependencies
    - bash: cibuildwheel --output-dir wheelhouse .
      displayName: Build wheels
@@ -11,7 +11,7 @@ jobs:
      - run:
          name: Build the Linux wheels.
          command: |
-            pip3 install --user cibuildwheel==1.10.1
+            pip3 install --user cibuildwheel==2.0.0b1
            cibuildwheel --output-dir wheelhouse
      - store_artifacts:
          path: wheelhouse/
@@ -19,13 +19,13 @@ jobs:
  osx-wheels:
    working_directory: ~/osx-wheels
    macos:
-      xcode: 10.0.0
+      xcode: 12.5.1
    steps:
      - checkout
      - run:
          name: Build the OS X wheels.
          command: |
-            pip3 install cibuildwheel==1.10.1
+            pip3 install cibuildwheel==2.0.0b1
            cibuildwheel --output-dir wheelhouse
      - store_artifacts:
          path: wheelhouse/
@@ -10,7 +10,7 @@ jobs:
      - uses: actions/checkout@v2

      - name: Build wheels
-        uses: joerick/cibuildwheel@v1.10.1
+        uses: pypa/cibuildwheel@v2.0.0b1
        env:
          CIBW_ARCHS_MACOS: x86_64 universal2

@@ -27,7 +27,7 @@ jobs:
          python-version: '3.8'

      - name: Build wheels
-        uses: joerick/cibuildwheel@v1.10.1
+        uses: pypa/cibuildwheel@v2.0.0b1

      - uses: actions/upload-artifact@v2
        with:
@@ -64,7 +64,7 @@ jobs:
          name: artifact
          path: dist

-      - uses: pypa/gh-action-pypi-publish@master
+      - uses: pypa/gh-action-pypi-publish@v1.4.2
        with:
          user: __token__
          password: ${{ secrets.pypi_password }}
@@ -14,7 +14,7 @@ jobs:
      - uses: actions/checkout@v2

      - name: Build wheels
-        uses: joerick/cibuildwheel@v1.10.1
+        uses: pypa/cibuildwheel@v2.0.0b1
        # to supply options, put them in 'env', like:
        # env:
        #   CIBW_SOME_OPTION: value
@@ -25,7 +25,7 @@ jobs:
          platforms: all

      - name: Build wheels
-        uses: joerick/cibuildwheel@v1.10.1
+        uses: pypa/cibuildwheel@v2.0.0b1
        env:
          # configure cibuildwheel to build native archs ('auto'), and some
          # emulated ones
@@ -12,7 +12,7 @@ linux:
    DOCKER_TLS_CERTDIR: ""
  script:
    - curl -sSL https://get.docker.com/ | sh
-    - python -m pip install cibuildwheel==1.10.1
+    - python -m pip install cibuildwheel==2.0.0b1
    - cibuildwheel --output-dir wheelhouse
  artifacts:
    paths:
@@ -1,15 +1,14 @@
 # As written, this configuration will build your wheels on every
 # commit, but will only push to PyPI on tagged commits.

+os: linux
+dist: focal
 language: python

 jobs:
  include:
    # perform a linux build
    - services: docker
-    # and a mac build
-    - os: osx
-      language: shell
    # and a windows build
    - os: windows
      language: shell
@@ -20,7 +19,7 @@ jobs:
        - ln -s /c/Python38/python.exe /c/Python38/python3.exe

 install:
-  - python3 -m pip install cibuildwheel==1.10.1
+  - python3 -m pip install cibuildwheel==2.0.0b1

 script:
  # build the wheels, put them into './wheelhouse'
@@ -1,3 +1,5 @@
+os: linux
+dist: focal
 language: python

 jobs:
@@ -13,9 +15,6 @@ jobs:
    # perform a linux S390X build
    - services: docker
      arch: s390x
-    # and a mac build
-    - os: osx
-      language: shell
    # and a windows build
    - os: windows
      language: shell
@@ -26,7 +25,7 @@ jobs:
        - ln -s /c/Python38/python.exe /c/Python38/python3.exe

 install:
-  - python3 -m pip install cibuildwheel==1.10.1
+  - python3 -m pip install cibuildwheel==2.0.0b1

 script:
  # build the wheels, put them into './wheelhouse'
@@ -1,10 +1,12 @@
 # In this configuration, the package is tested against multiple versions of python
 # on Linux and on one version of Python on Windows. If and only if all tests pass
 # will the wheels be built and deployed. Further, deployment is only initiated if
-# the current branch is "master", the current commit is tagged, and the current
+# the current branch is "main", the current commit is tagged, and the current
 # repo is yours (e.g. it won't run on a Pull Request). For convenience, a source
 # distribution is also created.

+os: linux
+dist: focal
 language: python
 python:
  - 3.6
@@ -32,9 +34,9 @@ stages:
  # Only execute deployment stage on tagged commits, and from your repository
  # (e.g. not PRs). Replace with your repo name.
  - name: deploy
-    if: tag IS PRESENT AND repo = joerick/cibuildwheel
+    if: tag IS PRESENT AND repo = pypa/cibuildwheel
    # To only build tags that look like vX.Y.Z:
-    #   if: tag =~ ^v\d+\.\d+\.\d+$ AND repo = joerick/cibuildwheel
+    #   if: tag =~ ^v\d+\.\d+\.\d+$ AND repo = pypa/cibuildwheel

 jobs:
  include:
@@ -55,17 +57,7 @@ jobs:
    - stage: deploy
      name: Build and deploy Linux wheels
      services: docker
-      install: python3 -m pip install cibuildwheel==1.10.1
-      script: python3 -m cibuildwheel --output-dir wheelhouse
-      after_success: |
-        python3 -m pip install twine
-        python3 -m twine upload --skip-existing wheelhouse/*.whl
-    # Deploy on mac
-    - stage: deploy
-      name: Build and deploy macOS wheels
-      os: osx
-      language: shell
-      install: python3 -m pip install cibuildwheel==1.10.1
+      install: python3 -m pip install cibuildwheel==2.0.0b1
      script: python3 -m cibuildwheel --output-dir wheelhouse
      after_success: |
        python3 -m pip install twine
@@ -75,7 +67,7 @@ jobs:
      name: Build and deploy Windows wheels
      os: windows
      language: shell
-      install: python3 -m pip install cibuildwheel==1.10.1
+      install: python3 -m pip install cibuildwheel==2.0.0b1
      script: python3 -m cibuildwheel --output-dir wheelhouse
      after_success: |
        python3 -m pip install twine
@@ -5,7 +5,8 @@ theme:
  highlightjs: true
  hljs_languages:
      - yaml
-repo_url: https://github.com/joerick/cibuildwheel
+repo_url: https://github.com/pypa/cibuildwheel
+edit_uri: edit/main/docs/

 extra_css:
  - extra.css
@@ -40,3 +41,7 @@ markdown_extensions:
 plugins:
  - include-markdown
  - search
+  - macros:
+      module_name: docs/main
+      j2_variable_start_string: «
+      j2_variable_end_string: »
@@ -0,0 +1,96 @@
+import shutil
+import sys
+from pathlib import Path
+
+import nox
+
+nox.options.sessions = ["lint", "tests"]
+
+PYTHON_ALL_VERSIONS = ["3.6", "3.7", "3.8", "3.9"]
+
+DIR = Path(__file__).parent.resolve()
+
+
+@nox.session
+def tests(session):
+    """
+    Run the unit and regular tests.
+    """
+    unit_test_args = ["--run-docker"] if sys.platform.startswith("linux") else []
+    session.install("-e", ".[test]")
+    if session.posargs:
+        session.run("pytest", *session.posargs)
+    else:
+        session.run("pytest", "unit_test", *unit_test_args)
+        session.run("pytest", "test", "-x", "--durations", "0", "--timeout=2400", "test")
+
+
+@nox.session
+def lint(session):
+    """
+    Run the linter.
+    """
+    session.install("pre-commit")
+    session.run("pre-commit", "run", "--all-files")
+
+
+@nox.session(python=PYTHON_ALL_VERSIONS)
+def update_constraints(session):
+    """
+    Update the dependencies inplace.
+    """
+    session.install("requests", "pip-tools")
+    session.run("python", "bin/update_dependencies.py")
+
+
+@nox.session
+def update_pins(session):
+    """
+    Update the python and docker pins version inplace.
+    """
+    session.install("-e", ".[bin]")
+    session.run("python", "bin/update_pythons.py", "--force")
+    session.run("python", "bin/update_docker.py")
+
+
+@nox.session
+def update_proj(session):
+    """
+    Update the README inplace.
+    """
+    session.install("-e", ".[bin]")
+    session.run("python", "bin/projects.py", "docs/data/projects.yml", "--readme=README.md")
+
+
+@nox.session
+def docs(session):
+    """
+    Build the docs.
+    """
+    session.install("-e", ".[docs]")
+
+    if session.posargs:
+        if "serve" in session.posargs:
+            session.run("mkdocs", "serve")
+        else:
+            print("Unrecognized args, use 'serve'")
+    else:
+        session.run("mkdocs", "build")
+
+
+@nox.session
+def build(session):
+    """
+    Build an SDist and wheel.
+    """
+
+    build_p = DIR.joinpath("build")
+    if build_p.exists():
+        shutil.rmtree(build_p)
+
+    dist_p = DIR.joinpath("dist")
+    if dist_p.exists():
+        shutil.rmtree(dist_p)
+
+    session.install("build")
+    session.run("python", "-m", "build")
@@ -6,7 +6,62 @@ requires = [

 build-backend = "setuptools.build_meta"

+
 [tool.black]
-line-length = 120
-target-version = ['py36', 'py37', 'py38']
-skip-string-normalization = true
+line-length = 100
+target-version = ['py36', 'py37', 'py38', 'py39']
+
+
+[tool.isort]
+profile = "black"
+multi_line_output = 3
+
+
+[tool.pytest.ini_options]
+minversion = 6.0
+junit_family = "xunit2"
+testpaths = [
+    "test",
+    "unit_test",
+]
+
+
+[tool.mypy]
+python_version = 3.7
+files = [
+    "cibuildwheel/*.py",
+    "test/**/*.py",
+    "unit_test/**/*.py",
+    "bin/*.py"
+]
+warn_unused_configs = true
+warn_redundant_casts = true
+no_implicit_reexport = true
+strict_equality = true
+warn_unused_ignores = true
+check_untyped_defs = true
+
+disallow_subclassing_any = true
+disallow_any_generics = true
+warn_return_any = true
+no_implicit_optional = true
+
+[[tool.mypy.overrides]]
+module = "cibuildwheel.*"
+disallow_untyped_defs = true
+disallow_untyped_calls = true
+disallow_incomplete_defs = true
+disallow_untyped_decorators = true
+
+[[tool.mypy.overrides]]
+module = [
+    "setuptools",
+    "pytest", # ignored in pre-commit to speed up check
+    "bashlex",
+    "toml.encoder", # encoder missing from stub package
+    "bracex",
+    "importlib_resources",
+    "nox",
+    "github",
+]
+ignore_missing_imports = true
@@ -1,10 +1,10 @@
 [metadata]
 name = cibuildwheel
-version = 1.10.1
+version = 2.0.0b1
 description = Build Python wheels on CI with minimal configuration.
 long_description = file: README.md
 long_description_content_type = text/markdown
-url = https://github.com/joerick/cibuildwheel
+url = https://github.com/pypa/cibuildwheel
 author = Joe Rickerby
 author_email = joerick@mac.com
 license = BSD
@@ -24,7 +24,7 @@ classifiers =
    Topic :: Software Development :: Build Tools
 keywords = ci,wheel,packaging,pypi,travis,appveyor,macos,linux,windows
 project_urls =
-    Changelog=https://github.com/joerick/cibuildwheel#changelog
+    Changelog=https://github.com/pypa/cibuildwheel#changelog
    Documentation=https://cibuildwheel.readthedocs.io/

 [options]
@@ -52,7 +52,7 @@ include =
    cibuildwheel

 [flake8]
-ignore = E501,W503,E741,E226,B950
+ignore = E501,W503,E741,E226,B950,E203
 select = C,E,F,W,B,B9
 application-import-names = cibuildwheel
 exclude =
@@ -65,57 +65,3 @@ exclude =
    env??/,
    .venv/,
    site/
-
-[tool:pytest]
-junit_family = xunit2
-testpaths =
-    test
-    unit_test
-
-[mypy]
-python_version = 3.7
-files = cibuildwheel/*.py,test/**/*.py,unit_test/**/*.py,bin/*.py
-warn_unused_configs = True
-warn_redundant_casts = True
-
-[mypy-test.*,mypy-unit_test.*]
-check_untyped_defs = True
-
-[mypy-cibuildwheel.*]
-disallow_any_generics = True
-disallow_subclassing_any = True
-disallow_untyped_calls = True
-disallow_untyped_defs = True
-disallow_incomplete_defs = True
-check_untyped_defs = True
-disallow_untyped_decorators = True
-no_implicit_optional = True
-warn_unused_ignores = True
-warn_return_any = True
-no_implicit_reexport = True
-strict_equality = True
-
-[mypy-setuptools.*]
-ignore_missing_imports = True
-
-# Ignored for pre-commit to speed up check
-# Not ignored if manually running and pytest installed
-[mypy-pytest.*]
-ignore_missing_imports = True
-
-[mypy-bashlex.*]
-ignore_missing_imports = True
-
-# Has type stubs, but no pyproject.toml or .pyi files in the wheel.
-[mypy-toml.*]
-ignore_missing_imports = True
-
-[mypy-bracex.*]
-ignore_missing_imports = True
-
-[mypy-importlib_resources.*]
-ignore_missing_imports = True
-
-[tool:isort]
-profile = black
-multi_line_output = 3
@@ -5,27 +5,42 @@ extras = {
        "mkdocs-include-markdown-plugin==2.8.0",
        "mkdocs==1.0.4",
        "pymdown-extensions",
+        "mkdocs-macros-plugin",
    ],
    "test": [
        "jinja2",
-        "pytest>=4",
+        "pytest>=6",
        "pytest-timeout",
    ],
-    "dev": [
+    "bin": [
        "click",
        "ghapi",
-        "mypy>=0.800",
-        "packaging>=20.8",
        "pip-tools",
        "pygithub",
        "pyyaml",
        "requests",
        "rich>=9.6",
-        "typing-extensions",
+        "packaging>=21.0",
+    ],
+    "mypy": [
+        "mypy>=0.901",
+        "types-jinja2",
+        "types-certifi",
+        "types-toml",
+        "types-jinja2",
+        "types-pyyaml",
+        "types-click",
+        "types-requests",
+        "types-toml",
    ],
 }

+extras["dev"] = [
+    *extras["mypy"],
+    *extras["test"],
+    *extras["bin"],
+]
+
 extras["all"] = sum(extras.values(), [])
-extras["dev"] += extras["test"]

 setup(extras_require=extras)
@@ -1,7 +1,9 @@
+from typing import Dict
+
 import pytest


-def pytest_addoption(parser):
+def pytest_addoption(parser) -> None:
    parser.addoption(
        "--run-emulation", action="store_true", default=False, help="run emulation tests"
    )
@@ -11,7 +13,7 @@ def pytest_configure(config):
    config.addinivalue_line("markers", "emulation: mark test requiring qemu binfmt_misc to run")


-def pytest_collection_modifyitems(config, items):
+def pytest_collection_modifyitems(config, items) -> None:
    if config.getoption("--run-emulation"):
        # --run-emulation given in cli: do not skip emulation tests
        return
@@ -19,3 +21,10 @@ def pytest_collection_modifyitems(config, items):
    for item in items:
        if "emulation" in item.keywords:
            item.add_marker(skip_emulation)
+
+
+@pytest.fixture(
+    params=[{"CIBW_BUILD_FRONTEND": "pip"}, {"CIBW_BUILD_FRONTEND": "build"}], ids=["pip", "build"]
+)
+def build_frontend_env(request) -> Dict[str, str]:
+    return request.param  # type: ignore
@@ -1,4 +1,3 @@
-import platform
 import textwrap

 import pytest
@@ -8,37 +7,39 @@ from cibuildwheel.logger import Logger
 from . import test_projects, utils

 basic_project = test_projects.new_c_project(
-    setup_py_add=textwrap.dedent('''
+    setup_py_add=textwrap.dedent(
+        """
        import os

        if os.environ.get("CIBUILDWHEEL", "0") != "1":
            raise Exception("CIBUILDWHEEL environment variable is not set to 1")
-    ''')
+        """
+    )
 )


-def test(tmp_path):
-    project_dir = tmp_path / 'project'
+def test(tmp_path, build_frontend_env):
+    project_dir = tmp_path / "project"
    basic_project.generate(project_dir)

    # build the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir)
+    actual_wheels = utils.cibuildwheel_run(project_dir, add_env=build_frontend_env)

    # check that the expected wheels are produced
-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)


-@pytest.mark.skip(reason='to keep test output clean')
+@pytest.mark.skip(reason="to keep test output clean")
 def test_sample_build(tmp_path, capfd):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    basic_project.generate(project_dir)

    # build the wheels, and let the output passthrough to the caller, so
    # we can see how it looks
    with capfd.disabled():
        logger = Logger()
-        logger.step('test_sample_build')
+        logger.step("test_sample_build")
        try:
            utils.cibuildwheel_run(project_dir)
        finally:
@@ -46,18 +47,13 @@ def test_sample_build(tmp_path, capfd):


 def test_build_identifiers(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    basic_project.generate(project_dir)

    # check that the number of expected wheels matches the number of build
    # identifiers
-    # after adding CIBW_MANYLINUX_IMAGE to support manylinux2010, there
-    # can be multiple wheels for each wheel, though, so we need to limit
-    # the expected wheels
-    if platform.machine() in ['x86_64', 'i686']:
-        expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                           if '-manylinux' not in w or '-manylinux1' in w]
-    else:
-        expected_wheels = utils.expected_wheels('spam', '0.1.0')
-    build_identifiers = utils.cibuildwheel_get_build_identifiers(project_dir)
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
+    build_identifiers = utils.cibuildwheel_get_build_identifiers(
+        project_dir, prerelease_pythons=True
+    )
    assert len(expected_wheels) == len(build_identifiers)
@@ -6,7 +6,8 @@ import pytest
 from . import test_projects, utils

 project_with_before_build_asserts = test_projects.new_c_project(
-    setup_py_add=textwrap.dedent(r'''
+    setup_py_add=textwrap.dedent(
+        r"""
        # assert that the Python version as written to text_info.txt in the CIBW_BEFORE_ALL step
        # is the same one as is currently running.
        with open("text_info.txt") as f:
@@ -14,52 +15,62 @@ project_with_before_build_asserts = test_projects.new_c_project(

        print("## stored text: " + stored_text)
        assert stored_text == "sample text 123"
-    ''')
+        """
+    )
 )


 def test(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_before_build_asserts.generate(project_dir)

-    with (project_dir / 'text_info.txt').open(mode='w') as ff:
+    with (project_dir / "text_info.txt").open(mode="w") as ff:
        print("dummy text", file=ff)

    # build the wheels
    before_all_command = '''python -c "import os;open('{project}/text_info.txt', 'w').write('sample text '+os.environ.get('TEST_VAL', ''))"'''
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        # write python version information to a temporary file, this is
-        # checked in setup.py
-        'CIBW_BEFORE_ALL': before_all_command,
-        'CIBW_BEFORE_ALL_LINUX': f'{before_all_command} && python -c "import sys; assert sys.version_info >= (3, 6)"',
-        'CIBW_ENVIRONMENT': "TEST_VAL='123'"
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            # write python version information to a temporary file, this is
+            # checked in setup.py
+            "CIBW_BEFORE_ALL": before_all_command,
+            "CIBW_BEFORE_ALL_LINUX": f'{before_all_command} && python -c "import sys; assert sys.version_info >= (3, 6)"',
+            "CIBW_ENVIRONMENT": "TEST_VAL='123'",
+        },
+    )

    # also check that we got the right wheels
-    (project_dir / 'text_info.txt').unlink()
-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    (project_dir / "text_info.txt").unlink()
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)


 def test_failing_command(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    test_projects.new_c_project().generate(project_dir)

    with pytest.raises(subprocess.CalledProcessError):
-        utils.cibuildwheel_run(project_dir, add_env={
-            'CIBW_BEFORE_ALL': 'false',
-            'CIBW_BEFORE_ALL_WINDOWS': 'exit /b 1',
-        })
+        utils.cibuildwheel_run(
+            project_dir,
+            add_env={
+                "CIBW_BEFORE_ALL": "false",
+                "CIBW_BEFORE_ALL_WINDOWS": "exit /b 1",
+            },
+        )


 def test_cwd(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    test_projects.new_c_project().generate(project_dir)

-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_BEFORE_ALL': f'''python -c "import os; assert os.getcwd() == {str(project_dir)!r}"''',
-        'CIBW_BEFORE_ALL_LINUX': '''python -c "import os; assert os.getcwd() == '/project'"''',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_BEFORE_ALL": f'''python -c "import os; assert os.getcwd() == {str(project_dir)!r}"''',
+            "CIBW_BEFORE_ALL_LINUX": '''python -c "import os; assert os.getcwd() == '/project'"''',
+        },
+    )

-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)
@@ -6,7 +6,8 @@ import pytest
 from . import test_projects, utils

 project_with_before_build_asserts = test_projects.new_c_project(
-    setup_py_add=textwrap.dedent(r'''
+    setup_py_add=textwrap.dedent(
+        r"""
        import os

        # assert that the Python version as written to pythonversion.txt in the CIBW_BEFORE_BUILD step
@@ -24,51 +25,68 @@ project_with_before_build_asserts = test_projects.new_c_project(
            stored_executable = f.read()
        print('stored_executable', stored_executable)
        print('sys.executable', sys.executable)
+
        # windows/mac are case insensitive
-        assert os.path.realpath(stored_executable).lower() == os.path.realpath(sys.executable).lower()
-    ''')
+        stored_path = os.path.realpath(stored_executable).lower()
+        current_path = os.path.realpath(sys.executable).lower()
+
+        # TODO: This is not valid in an virtual environment
+        assert stored_path == current_path, '{0} != {1}'.format(stored_path, current_path)
+        """
+    )
 )


 def test(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_before_build_asserts.generate(project_dir)

-    before_build = ('''python -c "import sys; open('{output_dir}pythonversion.txt', 'w').write(sys.version)" && '''
-                    '''python -c "import sys; open('{output_dir}pythonexecutable.txt', 'w').write(sys.executable)"''')
+    before_build = (
+        """python -c "import sys; open('{output_dir}pythonversion.txt', 'w').write(sys.version)" && """
+        '''python -c "import sys; open('{output_dir}pythonexecutable.txt', 'w').write(sys.executable)"'''
+    )

    # build the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        # write python version information to a temporary file, this is
-        # checked in setup.py
-        'CIBW_BEFORE_BUILD': before_build.format(output_dir='/tmp/'),
-        'CIBW_BEFORE_BUILD_WINDOWS': before_build.format(output_dir=r'c:\\'),
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            # write python version information to a temporary file, this is
+            # checked in setup.py
+            "CIBW_BEFORE_BUILD": before_build.format(output_dir="/tmp/"),
+            "CIBW_BEFORE_BUILD_WINDOWS": before_build.format(output_dir=r"c:\\"),
+        },
+    )

    # also check that we got the right wheels
-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)


 def test_failing_command(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    test_projects.new_c_project().generate(project_dir)

    with pytest.raises(subprocess.CalledProcessError):
-        utils.cibuildwheel_run(project_dir, add_env={
-            'CIBW_BEFORE_BUILD': 'false',
-            'CIBW_BEFORE_BUILD_WINDOWS': 'exit /b 1',
-        })
+        utils.cibuildwheel_run(
+            project_dir,
+            add_env={
+                "CIBW_BEFORE_BUILD": "false",
+                "CIBW_BEFORE_BUILD_WINDOWS": "exit /b 1",
+            },
+        )


 def test_cwd(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    test_projects.new_c_project().generate(project_dir)

-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_BEFORE_BUILD': f'''python -c "import os; assert os.getcwd() == {str(project_dir)!r}"''',
-        'CIBW_BEFORE_BUILD_LINUX': '''python -c "import os; assert os.getcwd() == '/project'"''',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_BEFORE_BUILD": f'''python -c "import os; assert os.getcwd() == {str(project_dir)!r}"''',
+            "CIBW_BEFORE_BUILD_LINUX": '''python -c "import os; assert os.getcwd() == '/project'"''',
+        },
+    )

-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)
@@ -1,7 +1,9 @@
 from . import test_projects, utils

 before_test_project = test_projects.new_c_project()
-before_test_project.files['test/spam_test.py'] = r'''
+before_test_project.files[
+    "test/spam_test.py"
+] = r"""
 import sys
 import os
 from unittest import TestCase
@@ -30,28 +32,31 @@ class TestBeforeTest(TestCase):
        #  vssadm~1 instead of vssadministrator

        assert os.stat(stored_prefix) == os.stat(sys.prefix)
-'''
+"""


 def test(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    before_test_project.generate(project_dir)
-    test_project_dir = project_dir / 'dependency'
+    test_project_dir = project_dir / "dependency"
    test_projects.new_c_project().generate(test_project_dir)

    # build the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        # write python version information to a temporary file, this is
-        # checked in setup.py
-        'CIBW_BEFORE_TEST': '''python -c "import sys; open('/tmp/pythonversion.txt', 'w').write(sys.version)" && python -c "import sys; open('/tmp/pythonprefix.txt', 'w').write(sys.prefix)" && python -m pip install {project}/dependency''',
-        'CIBW_BEFORE_TEST_WINDOWS': '''python -c "import sys; open('c:\\pythonversion.txt', 'w').write(sys.version)" && python -c "import sys; open('c:\\pythonprefix.txt', 'w').write(sys.prefix)" && python -m pip install {project}/dependency''',
-        'CIBW_TEST_REQUIRES': 'nose',
-        # the 'false ||' bit is to ensure this command runs in a shell on
-        # mac/linux.
-        'CIBW_TEST_COMMAND': 'false || nosetests {project}/test',
-        'CIBW_TEST_COMMAND_WINDOWS': 'nosetests {project}/test',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            # write python version information to a temporary file, this is
+            # checked in setup.py
+            "CIBW_BEFORE_TEST": """python -c "import sys; open('/tmp/pythonversion.txt', 'w').write(sys.version)" && python -c "import sys; open('/tmp/pythonprefix.txt', 'w').write(sys.prefix)" && python -m pip install {project}/dependency""",
+            "CIBW_BEFORE_TEST_WINDOWS": """python -c "import sys; open('c:\\pythonversion.txt', 'w').write(sys.version)" && python -c "import sys; open('c:\\pythonprefix.txt', 'w').write(sys.prefix)" && python -m pip install {project}/dependency""",
+            "CIBW_TEST_REQUIRES": "pytest",
+            # the 'false ||' bit is to ensure this command runs in a shell on
+            # mac/linux.
+            "CIBW_TEST_COMMAND": "false || pytest {project}/test",
+            "CIBW_TEST_COMMAND_WINDOWS": "pytest {project}/test",
+        },
+    )

    # also check that we got the right wheels
-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)
@@ -3,27 +3,33 @@ import textwrap
 from . import test_projects, utils

 project_with_skip_asserts = test_projects.new_c_project(
-    setup_py_add=textwrap.dedent(r'''
-        # explode if run on Python 2.7 or Python 3.7 (these should be skipped)
-        if sys.version_info[0:2] == (2, 7):
-            raise Exception("Python 2.7 should not be built")
+    setup_py_add=textwrap.dedent(
+        r"""
+        # explode if run on PyPyor Python 3.7 (these should be skipped)
+        if sys.implementation.name != "cpython":
+            raise Exception("Only CPython shall be built")
        if sys.version_info[0:2] == (3, 7):
-            raise Exception("Python 3.7 should be skipped")
-    ''')
+            raise Exception("CPython 3.7 should be skipped")
+        """
+    )
 )


 def test(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_skip_asserts.generate(project_dir)

    # build the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_BUILD': 'cp3?-*',
-        'CIBW_SKIP': 'cp37-*',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_BUILD": "cp3*-*",
+            "CIBW_SKIP": "cp37-*",
+        },
+    )

-    # check that we got the right wheels. There should be no 2.7 or 3.7.
-    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                       if ('-cp3' in w) and ('-cp37' not in w)]
+    # check that we got the right wheels. There should be no PyPy or 3.7.
+    expected_wheels = [
+        w for w in utils.expected_wheels("spam", "0.1.0") if ("-cp3" in w) and ("-cp37" not in w)
+    ]
    assert set(actual_wheels) == set(expected_wheels)
@@ -8,7 +8,7 @@ from .test_projects import TestProject

 cpp_test_project = TestProject()

-cpp_test_project.files['setup.py'] = jinja2.Template(r'''
+setup_py_template = r"""
 from setuptools import Extension, setup

 setup(
@@ -16,9 +16,9 @@ setup(
    ext_modules=[Extension('spam', sources=['spam.cpp'], language="c++", extra_compile_args={{ extra_compile_args }})],
    version="0.1.0",
 )
-''')
+"""

-cpp_test_project.files['spam.cpp'] = jinja2.Template(r'''
+spam_cpp_template = r"""
 #include <Python.h>

 {{ spam_cpp_top_level_add }}
@@ -36,174 +36,96 @@ spam_system(PyObject *self, PyObject *args)
 }

 /* Module initialization */
-
-#if PY_MAJOR_VERSION >= 3
-    #define MOD_INIT(name) PyMODINIT_FUNC PyInit_##name(void)
-    #define MOD_DEF(m, name, doc, methods, module_state_size) \
-        static struct PyModuleDef moduledef = { \
-            PyModuleDef_HEAD_INIT, name, doc, module_state_size, methods, }; \
-        m = PyModule_Create(&moduledef);
-    #define MOD_RETURN(m) return m;
-#else
-    #define MOD_INIT(name) PyMODINIT_FUNC init##name(void)
-    #define MOD_DEF(m, name, doc, methods, module_state_size) \
-        m = Py_InitModule3(name, methods, doc);
-    #define MOD_RETURN(m) return;
-#endif
-
 static PyMethodDef module_methods[] = {
    {"system", (PyCFunction)spam_system, METH_VARARGS,
     "Execute a shell command."},
    {NULL}  /* Sentinel */
 };

-MOD_INIT(spam)
+PyMODINIT_FUNC PyInit_spam(void)
 {
-    PyObject* m;
-
-    MOD_DEF(m,
-            "spam",
-            "Example module",
-            module_methods,
-            -1)
-
-    MOD_RETURN(m)
+    static struct PyModuleDef moduledef = {
+        PyModuleDef_HEAD_INIT, "spam", "Example module", -1, module_methods,
+    };
+    return PyModule_Create(&moduledef);
 }
-''')
+"""

+cpp_test_project.files["setup.py"] = jinja2.Template(setup_py_template)
+cpp_test_project.files["spam.cpp"] = jinja2.Template(spam_cpp_template)

 cpp11_project = cpp_test_project.copy()
-cpp11_project.template_context['extra_compile_args'] = (
-    ['/std:c++11'] if utils.platform == 'windows' else ['-std=c++11']
+cpp11_project.template_context["extra_compile_args"] = (
+    ["/std:c++11"] if utils.platform == "windows" else ["-std=c++11"]
 )
-cpp11_project.template_context['spam_cpp_top_level_add'] = '#include <array>'
+cpp11_project.template_context["spam_cpp_top_level_add"] = "#include <array>"


 def test_cpp11(tmp_path):
    # This test checks that the C++11 standard is supported
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"

    cpp11_project.generate(project_dir)

-    # VC++ for Python 2.7 does not support modern standards
-    add_env = {'CIBW_SKIP': 'cp27-win* pp27-win32'}
-
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env=add_env)
-    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                       if 'cp27-cp27m-win' not in w and 'pp27-pypy_73-win32' not in w]
+    actual_wheels = utils.cibuildwheel_run(project_dir)
+    expected_wheels = [w for w in utils.expected_wheels("spam", "0.1.0")]

    assert set(actual_wheels) == set(expected_wheels)


 cpp14_project = cpp_test_project.copy()
-cpp14_project.template_context['extra_compile_args'] = (
-    ['/std:c++14'] if utils.platform == 'windows' else ['-std=c++14']
+cpp14_project.template_context["extra_compile_args"] = (
+    ["/std:c++14"] if utils.platform == "windows" else ["-std=c++14"]
 )
-cpp14_project.template_context['spam_cpp_top_level_add'] = "int a = 100'000;"
+cpp14_project.template_context["spam_cpp_top_level_add"] = "int a = 100'000;"


 def test_cpp14(tmp_path):
    # This test checks that the C++14 standard is supported
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"

    cpp14_project.generate(project_dir)

-    # VC++ for Python 2.7 does not support modern standards
-    # The manylinux1 docker image does not have a compiler which supports C++11
-    add_env = {'CIBW_SKIP': 'cp27-win* pp27-win32'}
-
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env=add_env)
-    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                       if 'cp27-cp27m-win' not in w
-                       and 'pp27-pypy_73-win32' not in w]
+    actual_wheels = utils.cibuildwheel_run(project_dir)
+    expected_wheels = [w for w in utils.expected_wheels("spam", "0.1.0")]

    assert set(actual_wheels) == set(expected_wheels)


 cpp17_project = cpp_test_project.copy()

-# Python and PyPy 2.7 headers use the `register` keyword, which is forbidden in
-# the C++17 standard, so we need the -Wno-register or /wd5033 options
-cpp17_project.template_context['extra_compile_args'] = (
-    ['/std:c++17', '/wd5033'] if utils.platform == 'windows' else ['-std=c++17', '-Wno-register']
-)
-cpp17_project.template_context['spam_cpp_top_level_add'] = r'''
+cpp17_project.template_context["extra_compile_args"] = [
+    "/std:c++17" if utils.platform == "windows" else "-std=c++17"
+]
+cpp17_project.template_context[
+    "spam_cpp_top_level_add"
+] = r"""
 #include <utility>
 auto a = std::pair(5.0, false);
-'''
+"""


 def test_cpp17(tmp_path):
    # This test checks that the C++17 standard is supported
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"

    cpp17_project.generate(project_dir)

-    if os.environ.get('APPVEYOR_BUILD_WORKER_IMAGE', '') == 'Visual Studio 2015':
-        pytest.skip('Visual Studio 2015 does not support C++17')
+    if os.environ.get("APPVEYOR_BUILD_WORKER_IMAGE", "") == "Visual Studio 2015":
+        pytest.skip("Visual Studio 2015 does not support C++17")

    # Pypy's distutils sets the default compiler to 'msvc9compiler', which
    # is too old to support cpp17.
-    add_env = {'CIBW_SKIP': 'cp27-win* pp??-*'}
+    add_env = {"CIBW_SKIP": "pp??-*"}

-    if utils.platform == 'macos':
-        add_env['MACOSX_DEPLOYMENT_TARGET'] = '10.13'
+    if utils.platform == "macos":
+        add_env["MACOSX_DEPLOYMENT_TARGET"] = "10.13"

    actual_wheels = utils.cibuildwheel_run(project_dir, add_env=add_env)
-    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0', macosx_deployment_target='10.13')
-                       if 'cp27-cp27m-win' not in w
-                       and '-pp' not in w]
-
-    assert set(actual_wheels) == set(expected_wheels)
-
-
-def test_cpp17_py27_modern_msvc_workaround(tmp_path):
-    # This test checks the workaround for building Python 2.7 wheel with MSVC 14
-
-    if utils.platform != 'windows':
-        pytest.skip('the test is only relevant to the Windows build')
-
-    if os.environ.get('APPVEYOR_BUILD_WORKER_IMAGE', '') == 'Visual Studio 2015':
-        pytest.skip('Visual Studio 2015 does not support C++17')
-
-    project_dir = tmp_path / 'project'
-    cpp17_project.generate(project_dir)
-
-    # VC++ for Python 2.7 (i.e., MSVC 9) does not support modern standards
-    # This is a workaround which forces distutils/setupstools to a newer version
-    # Wheels compiled need a more modern C++ redistributable installed, which is not
-    # included with Python: see documentation for more info
-    # DISTUTILS_USE_SDK and MSSdk=1 tell distutils/setuptools that we are adding
-    # MSVC's compiler, tools, and libraries to PATH ourselves
-    add_env = {'DISTUTILS_USE_SDK': '1', 'MSSdk': '1'}
-
-    # Use existing setuptools code to run Visual Studio's vcvarsall.bat and get the
-    # necessary environment variables, since running vcvarsall.bat in a subprocess
-    # does not keep the relevant environment variables
-    # There are different environment variables for 32-bit/64-bit targets, so we
-    # need to run cibuildwheel twice, once for 32-bit with `vcvarsall.bat x86, and
-    # once for 64-bit with `vcvarsall.bat x64`
-    # In a normal CI setup, just run vcvarsall.bat before running cibuildwheel and set
-    # DISTUTILS_USE_SDK and MSSdk
-    import setuptools
-
-    def add_vcvars(prev_env, platform):
-        vcvarsall_env = setuptools.msvc.msvc14_get_vc_env(platform)
-        env = prev_env.copy()
-        for vcvar in ['path', 'include', 'lib']:
-            env[vcvar] = vcvarsall_env[vcvar]
-        return env
-
-    add_env_x86 = add_vcvars(add_env, 'x86')
-    add_env_x86['CIBW_BUILD'] = '?p27-win32'
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env=add_env_x86)
-
-    add_env_x64 = add_vcvars(add_env, 'x64')
-    add_env_x64['CIBW_BUILD'] = 'cp27-win_amd64'
-    actual_wheels += utils.cibuildwheel_run(project_dir, add_env=add_env_x64)
-
-    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0', exclude_27=False)
-                       if 'cp27-cp27m-win' in w
-                       or 'pp27-pypy_73-win32' in w]
+    expected_wheels = [
+        w
+        for w in utils.expected_wheels("spam", "0.1.0", macosx_deployment_target="10.13")
+        if "-pp" not in w
+    ]

    assert set(actual_wheels) == set(expected_wheels)
@@ -8,7 +8,8 @@ import cibuildwheel.util
 from . import test_projects, utils

 project_with_expected_version_checks = test_projects.new_c_project(
-    setup_py_add=textwrap.dedent(r'''
+    setup_py_add=textwrap.dedent(
+        r"""
        import subprocess
        import os

@@ -30,145 +31,131 @@ project_with_expected_version_checks = test_projects.new_c_project(
            assert '{}=={}'.format(package_name, expected_version) in versions, (
                'error: {} version should equal {}'.format(package_name, expected_version)
            )
-    ''')
+        """
+    )
 )


-VERSION_REGEX = r'([\w-]+)==([^\s]+)'
+VERSION_REGEX = r"([\w-]+)==([^\s]+)"


 def get_versions_from_constraint_file(constraint_file):
-    constraint_file_text = constraint_file.read_text(encoding='utf8')
+    constraint_file_text = constraint_file.read_text(encoding="utf8")

    return {
-        package: version
-        for package, version in re.findall(VERSION_REGEX, constraint_file_text)
+        package: version for package, version in re.findall(VERSION_REGEX, constraint_file_text)
    }


-@pytest.mark.parametrize('python_version', ['2.7', '3.5', '3.6', '3.8'])
-def test_pinned_versions(tmp_path, python_version):
-    if utils.platform == 'linux':
-        pytest.skip('linux doesn\'t pin individual tool versions, it pins manylinux images instead')
+@pytest.mark.parametrize("python_version", ["3.6", "3.8", "3.9"])
+def test_pinned_versions(tmp_path, python_version, build_frontend_env):
+    if utils.platform == "linux":
+        pytest.skip("linux doesn't pin individual tool versions, it pins manylinux images instead")

-    if utils.platform == 'windows' and python_version == '2.7':
-        pytest.skip('Windows requires a workaround')
-
-    is_running_on_macos_11_or_later = (
-        utils.platform == 'macos' and utils.get_macos_version() >= (10, 16)
-    )
-
-    if is_running_on_macos_11_or_later and python_version == '3.5':
-        pytest.skip('CPython 3.5 doesn\'t work on macOS Big Sur+')
-
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_expected_version_checks.generate(project_dir)

    build_environment = {}

-    if python_version == '2.7':
-        constraint_filename = 'constraints-python27.txt'
-        build_pattern = '[cp]p27-*'
-    elif python_version == '3.5':
-        constraint_filename = 'constraints-python35.txt'
-        build_pattern = '[cp]p35-*'
-    elif python_version == '3.6':
-        constraint_filename = 'constraints-python36.txt'
-        build_pattern = '[cp]p36-*'
-    elif python_version == '3.7':
-        constraint_filename = 'constraints-python37.txt'
-        build_pattern = '[cp]p37-*'
+    if python_version == "3.6":
+        constraint_filename = "constraints-python36.txt"
+        build_pattern = "[cp]p36-*"
+    elif python_version == "3.7":
+        constraint_filename = "constraints-python37.txt"
+        build_pattern = "[cp]p37-*"
+    elif python_version == "3.8":
+        constraint_filename = "constraints-python38.txt"
+        build_pattern = "[cp]p38-*"
    else:
-        constraint_filename = 'constraints.txt'
-        build_pattern = '[cp]p38-*'
+        constraint_filename = "constraints.txt"
+        build_pattern = "[cp]p39-*"

    constraint_file = cibuildwheel.util.resources_dir / constraint_filename
    constraint_versions = get_versions_from_constraint_file(constraint_file)

-    for package in ['pip', 'setuptools', 'wheel', 'virtualenv']:
-        env_name = f'EXPECTED_{package.upper()}_VERSION'
+    for package in ["pip", "setuptools", "wheel", "virtualenv"]:
+        env_name = f"EXPECTED_{package.upper()}_VERSION"
        build_environment[env_name] = constraint_versions[package]

-    cibw_environment_option = ' '.join(
-        f'{k}={v}' for k, v in build_environment.items()
-    )
+    cibw_environment_option = " ".join(f"{k}={v}" for k, v in build_environment.items())

    # build and test the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_BUILD': build_pattern,
-        'CIBW_ENVIRONMENT': cibw_environment_option,
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_BUILD": build_pattern,
+            "CIBW_ENVIRONMENT": cibw_environment_option,
+            **build_frontend_env,
+        },
+    )

    # also check that we got the right wheels
-    if python_version == '2.7':
-        expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                           if '-cp27' in w or '-pp27' in w]
-    elif python_version == '3.5':
-        expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                           if '-cp35' in w or '-pp35' in w]
-    elif python_version == '3.6':
-        expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                           if '-cp36' in w or '-pp36' in w]
-    elif python_version == '3.8':
-        expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                           if '-cp38' in w or '-pp38' in w]
+    if python_version == "3.6":
+        expected_wheels = [
+            w for w in utils.expected_wheels("spam", "0.1.0") if "-cp36" in w or "-pp36" in w
+        ]
+    elif python_version == "3.8":
+        expected_wheels = [
+            w for w in utils.expected_wheels("spam", "0.1.0") if "-cp38" in w or "-pp38" in w
+        ]
+    elif python_version == "3.9":
+        expected_wheels = [
+            w for w in utils.expected_wheels("spam", "0.1.0") if "-cp39" in w or "-pp39" in w
+        ]
    else:
-        raise ValueError('unhandled python version')
+        raise ValueError("unhandled python version")

    assert set(actual_wheels) == set(expected_wheels)


-@pytest.mark.parametrize('python_version', ['2.7', '3.x'])
-def test_dependency_constraints_file(tmp_path, python_version):
-    if utils.platform == 'linux':
-        pytest.skip('linux doesn\'t pin individual tool versions, it pins manylinux images instead')
+def test_dependency_constraints_file(tmp_path, build_frontend_env):
+    if utils.platform == "linux":
+        pytest.skip("linux doesn't pin individual tool versions, it pins manylinux images instead")

-    if utils.platform == 'windows' and python_version == '2.7':
-        pytest.skip('Windows + Travis CI requires a workaround')
-
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_expected_version_checks.generate(project_dir)

    tool_versions = {
-        'pip': '20.0.2',
-        'setuptools': '44.0.0' if python_version == '2.7' else '46.0.0',
-        'wheel': '0.34.2',
-        'virtualenv': '20.0.10',
+        "pip": "20.0.2",
+        "setuptools": "53.0.0",
+        "wheel": "0.34.2",
+        "virtualenv": "20.0.35",
    }

-    constraints_file = tmp_path / 'constraints.txt'
-    constraints_file.write_text(textwrap.dedent(
-        '''
+    constraints_file = tmp_path / "constraints file.txt"
+    constraints_file.write_text(
+        textwrap.dedent(
+            """
            pip=={pip}
            setuptools=={setuptools}
            wheel=={wheel}
            virtualenv=={virtualenv}
-        '''.format(**tool_versions)
-    ))
+            importlib-metadata<3,>=0.12; python_version < "3.8"
+            """.format(
+                **tool_versions
+            )
+        )
+    )

    build_environment = {}

    for package_name, version in tool_versions.items():
-        env_name = f'EXPECTED_{package_name.upper()}_VERSION'
+        env_name = f"EXPECTED_{package_name.upper()}_VERSION"
        build_environment[env_name] = version

-    cibw_environment_option = ' '.join(
-        f'{k}={v}' for k, v in build_environment.items()
-    )
+    cibw_environment_option = " ".join(f"{k}={v}" for k, v in build_environment.items())

    # build and test the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_BUILD': '[cp]p27-*' if python_version == '2.7' else '[cp]p3?-*',
-        'CIBW_ENVIRONMENT': cibw_environment_option,
-        'CIBW_DEPENDENCY_VERSIONS': str(constraints_file),
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_ENVIRONMENT": cibw_environment_option,
+            "CIBW_DEPENDENCY_VERSIONS": str(constraints_file),
+            **build_frontend_env,
+        },
+    )

    # also check that we got the right wheels
-    if python_version == '2.7':
-        expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                           if '-cp27' in w or '-pp27' in w]
-    else:
-        expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                           if '-cp27' not in w and '-pp27' not in w]
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")

    assert set(actual_wheels) == set(expected_wheels)
@@ -6,7 +6,8 @@ import pytest
 from . import test_projects, utils

 dockcross_only_project = test_projects.new_c_project(
-    setup_py_add=textwrap.dedent(r'''
+    setup_py_add=textwrap.dedent(
+        r"""
        import os

        # check that we're running in the correct docker image as specified in the
@@ -15,26 +16,35 @@ dockcross_only_project = test_projects.new_c_project(
            raise Exception(
                "/dockcross directory not found. Is this test running in the correct docker image?"
            )
-    ''')
+        """
+    )
 )


 def test(tmp_path):
-    if utils.platform != 'linux':
-        pytest.skip('the test is only relevant to the linux build')
-    if platform.machine() not in ['x86_64', 'i686']:
-        pytest.skip('this test is currently only possible on x86_64/i686 due to availability of alternative images')
+    if utils.platform != "linux":
+        pytest.skip("the test is only relevant to the linux build")
+    if platform.machine() not in ["x86_64", "i686"]:
+        pytest.skip(
+            "this test is currently only possible on x86_64/i686 due to availability of alternative images"
+        )

-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    dockcross_only_project.generate(project_dir)

-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_MANYLINUX_X86_64_IMAGE': 'dockcross/manylinux2010-x64',
-        'CIBW_MANYLINUX_I686_IMAGE': 'dockcross/manylinux2010-x86',
-        'CIBW_SKIP': 'pp* cp27-* cp39-*',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_MANYLINUX_X86_64_IMAGE": "dockcross/manylinux2010-x64",
+            "CIBW_MANYLINUX_I686_IMAGE": "dockcross/manylinux2010-x86",
+            "CIBW_BUILD": "cp3{6,7,8,9}-*",
+        },
+    )

    # also check that we got the right wheels built
-    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                       if '-pp' not in w and '-cp39-' not in w and '-cp27-' not in w]
+    expected_wheels = [
+        w
+        for w in utils.expected_wheels("spam", "0.1.0")
+        if "-cp36-" in w or "-cp37-" in w or "-cp38-" in w or "-cp39-" in w
+    ]
    assert set(actual_wheels) == set(expected_wheels)
@@ -6,48 +6,56 @@ from . import test_projects, utils

 project_with_a_test = test_projects.new_c_project()

-project_with_a_test.files['test/spam_test.py'] = r'''
+project_with_a_test.files[
+    "test/spam_test.py"
+] = r"""
 import spam

 def test_spam():
    assert spam.system('python -c "exit(0)"') == 0
    assert spam.system('python -c "exit(1)"') != 0
-'''
+"""


@pytest.mark.emulation
 def test(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_a_test.generate(project_dir)

    # build and test the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_TEST_REQUIRES': 'pytest',
-        'CIBW_TEST_COMMAND': 'pytest {project}/test',
-        'CIBW_ARCHS': 'aarch64 ppc64le s390x',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_TEST_REQUIRES": "pytest",
+            "CIBW_TEST_COMMAND": "pytest {project}/test",
+            "CIBW_ARCHS": "aarch64 ppc64le s390x",
+        },
+    )

    # also check that we got the right wheels
    expected_wheels = (
-        utils.expected_wheels('spam', '0.1.0', machine_arch='aarch64')
-        + utils.expected_wheels('spam', '0.1.0', machine_arch='ppc64le')
-        + utils.expected_wheels('spam', '0.1.0', machine_arch='s390x')
+        utils.expected_wheels("spam", "0.1.0", machine_arch="aarch64")
+        + utils.expected_wheels("spam", "0.1.0", machine_arch="ppc64le")
+        + utils.expected_wheels("spam", "0.1.0", machine_arch="s390x")
    )
    assert set(actual_wheels) == set(expected_wheels)


 def test_setting_arch_on_other_platforms(tmp_path, capfd):
-    if utils.platform == 'linux':
-        pytest.skip('this test checks the behaviour on platforms other than linux')
+    if utils.platform == "linux":
+        pytest.skip("this test checks the behaviour on platforms other than linux")

-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_a_test.generate(project_dir)

    # build and test the wheels
    with pytest.raises(subprocess.CalledProcessError):
-        utils.cibuildwheel_run(project_dir, add_env={
-            'CIBW_ARCHS': 'aarch64',
-        })
+        utils.cibuildwheel_run(
+            project_dir,
+            add_env={
+                "CIBW_ARCHS": "aarch64",
+            },
+        )

    captured = capfd.readouterr()
    assert "Invalid archs option" in captured.err
@@ -7,7 +7,8 @@ import pytest
 from . import test_projects, utils

 project_with_environment_asserts = test_projects.new_c_project(
-    setup_py_add=textwrap.dedent(r'''
+    setup_py_add=textwrap.dedent(
+        r"""
        import os

        # explode if environment isn't correct, as set in CIBW_ENVIRONMENT
@@ -26,30 +27,34 @@ project_with_environment_asserts = test_projects.new_c_project(
            raise Exception('PATH should contain "/opt/cibw_test_path". It was "%s"' % PATH)
        if "$PATH" in PATH:
            raise Exception('$PATH should be expanded in PATH. It was "%s"' % PATH)
-    ''')
+        """
+    )
 )


 def test(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_environment_asserts.generate(project_dir)

    # write some information into the CIBW_ENVIRONMENT, for expansion and
    # insertion into the environment by cibuildwheel. This is checked
    # in setup.py
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_ENVIRONMENT': '''CIBW_TEST_VAR="a b c" CIBW_TEST_VAR_2=1 CIBW_TEST_VAR_3="$(echo 'test string 3')" PATH=$PATH:/opt/cibw_test_path''',
-        'CIBW_ENVIRONMENT_WINDOWS': '''CIBW_TEST_VAR="a b c" CIBW_TEST_VAR_2=1 CIBW_TEST_VAR_3="$(echo 'test string 3')" PATH="$PATH;/opt/cibw_test_path"''',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_ENVIRONMENT": """CIBW_TEST_VAR="a b c" CIBW_TEST_VAR_2=1 CIBW_TEST_VAR_3="$(echo 'test string 3')" PATH=$PATH:/opt/cibw_test_path""",
+            "CIBW_ENVIRONMENT_WINDOWS": '''CIBW_TEST_VAR="a b c" CIBW_TEST_VAR_2=1 CIBW_TEST_VAR_3="$(echo 'test string 3')" PATH="$PATH;/opt/cibw_test_path"''',
+        },
+    )

    # also check that we got the right wheels built
-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)


 def test_overridden_path(tmp_path, capfd):
-    project_dir = tmp_path / 'project'
-    output_dir = tmp_path / 'output'
+    project_dir = tmp_path / "project"
+    output_dir = tmp_path / "output"

    project = test_projects.new_c_project()
    project.generate(project_dir)
@@ -57,20 +62,28 @@ def test_overridden_path(tmp_path, capfd):

    # mess up PATH, somehow
    with pytest.raises(subprocess.CalledProcessError):
-        if utils.platform == 'linux':
-            utils.cibuildwheel_run(project_dir, output_dir=output_dir, add_env={
-                'CIBW_BEFORE_ALL': 'mkdir new_path && touch new_path/python && chmod +x new_path/python',
-                'CIBW_ENVIRONMENT': '''PATH="$(pwd)/new_path:$PATH"''',
-            })
+        if utils.platform == "linux":
+            utils.cibuildwheel_run(
+                project_dir,
+                output_dir=output_dir,
+                add_env={
+                    "CIBW_BEFORE_ALL": "mkdir new_path && touch new_path/python && chmod +x new_path/python",
+                    "CIBW_ENVIRONMENT": '''PATH="$(pwd)/new_path:$PATH"''',
+                },
+            )
        else:
-            new_path = tmp_path / 'another_bin'
+            new_path = tmp_path / "another_bin"
            new_path.mkdir()
-            (new_path / 'python').touch(mode=0o777)
+            (new_path / "python").touch(mode=0o777)

-            utils.cibuildwheel_run(project_dir, output_dir=output_dir, add_env={
-                'NEW_PATH': str(new_path),
-                'CIBW_ENVIRONMENT': f'''PATH="$NEW_PATH{os.pathsep}$PATH"''',
-            })
+            utils.cibuildwheel_run(
+                project_dir,
+                output_dir=output_dir,
+                add_env={
+                    "NEW_PATH": str(new_path),
+                    "CIBW_ENVIRONMENT": f'''PATH="$NEW_PATH{os.pathsep}$PATH"''',
+                },
+            )

    assert len(os.listdir(output_dir)) == 0
    captured = capfd.readouterr()
@@ -8,15 +8,15 @@ from . import test_projects, utils

 basic_project = test_projects.new_c_project()

-ALL_MACOS_WHEELS = (
-    utils.expected_wheels('spam', '0.1.0', machine_arch='x86_64')
-    + utils.expected_wheels('spam', '0.1.0', machine_arch='arm64')
-)
+ALL_MACOS_WHEELS = {
+    *utils.expected_wheels("spam", "0.1.0", machine_arch="x86_64"),
+    *utils.expected_wheels("spam", "0.1.0", machine_arch="arm64"),
+}


 def get_xcode_version() -> Tuple[int, int]:
    output = subprocess.run(
-        ['xcodebuild', '-version'],
+        ["xcodebuild", "-version"],
        universal_newlines=True,
        check=True,
        stdout=subprocess.PIPE,
@@ -24,98 +24,112 @@ def get_xcode_version() -> Tuple[int, int]:
    lines = output.splitlines()
    _, version_str = lines[0].split()

-    version_parts = version_str.split('.')
+    version_parts = version_str.split(".")
    return (int(version_parts[0]), int(version_parts[1]))


 def test_cross_compiled_build(tmp_path):
-    if utils.platform != 'macos':
-        pytest.skip('this test is only relevant to macos')
+    if utils.platform != "macos":
+        pytest.skip("this test is only relevant to macos")
    if get_xcode_version() < (12, 2):
-        pytest.skip('this test only works with Xcode 12.2 or greater')
+        pytest.skip("this test only works with Xcode 12.2 or greater")

-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    basic_project.generate(project_dir)

-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_BUILD': 'cp39-*',
-        'CIBW_ARCHS': 'x86_64, universal2, arm64',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_BUILD": "cp39-*",
+            "CIBW_ARCHS": "x86_64, universal2, arm64",
+        },
+    )

-    expected_wheels = [w for w in ALL_MACOS_WHEELS if 'cp39' in w]
+    expected_wheels = [w for w in ALL_MACOS_WHEELS if "cp39" in w]
    assert set(actual_wheels) == set(expected_wheels)


-@pytest.mark.parametrize('build_universal2', [False, True])
+@pytest.mark.parametrize("build_universal2", [False, True])
 def test_cross_compiled_test(tmp_path, capfd, build_universal2):
-    if utils.platform != 'macos':
-        pytest.skip('this test is only relevant to macos')
+    if utils.platform != "macos":
+        pytest.skip("this test is only relevant to macos")
    if get_xcode_version() < (12, 2):
-        pytest.skip('this test only works with Xcode 12.2 or greater')
+        pytest.skip("this test only works with Xcode 12.2 or greater")

-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    basic_project.generate(project_dir)

-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_BUILD': 'cp39-*',
-        'CIBW_TEST_COMMAND': '''python -c "import platform; print('running tests on ' + platform.machine())"''',
-        'CIBW_ARCHS': 'universal2' if build_universal2 else 'x86_64 arm64',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_BUILD": "cp39-*",
+            "CIBW_TEST_COMMAND": '''python -c "import platform; print('running tests on ' + platform.machine())"''',
+            "CIBW_ARCHS": "universal2" if build_universal2 else "x86_64 arm64",
+        },
+    )

    captured = capfd.readouterr()

-    if platform.machine() == 'x86_64':
+    if platform.machine() == "x86_64":
        # ensure that tests were run on only x86_64
-        assert 'running tests on x86_64' in captured.out
-        assert 'running tests on arm64' not in captured.out
+        assert "running tests on x86_64" in captured.out
+        assert "running tests on arm64" not in captured.out
        if build_universal2:
-            assert 'While universal2 wheels can be built on x86_64, the arm64 part of them cannot currently be tested' in captured.err
+            assert (
+                "While universal2 wheels can be built on x86_64, the arm64 part of them cannot currently be tested"
+                in captured.err
+            )
        else:
-            assert 'While arm64 wheels can be built on x86_64, they cannot be tested' in captured.err
-    elif platform.machine() == 'arm64':
+            assert (
+                "While arm64 wheels can be built on x86_64, they cannot be tested" in captured.err
+            )
+    elif platform.machine() == "arm64":
        # ensure that tests were run on both x86_64 and arm64
-        assert 'running tests on x86_64' in captured.out
-        assert 'running tests on arm64' in captured.out
+        assert "running tests on x86_64" in captured.out
+        assert "running tests on arm64" in captured.out

    if build_universal2:
-        expected_wheels = [w for w in ALL_MACOS_WHEELS if 'cp39' in w and 'universal2' in w]
+        expected_wheels = [w for w in ALL_MACOS_WHEELS if "cp39" in w and "universal2" in w]
    else:
-        expected_wheels = [w for w in ALL_MACOS_WHEELS if 'cp39' in w and 'universal2' not in w]
+        expected_wheels = [w for w in ALL_MACOS_WHEELS if "cp39" in w and "universal2" not in w]

    assert set(actual_wheels) == set(expected_wheels)


-@pytest.mark.parametrize('skip_arm64_test', [False, True])
+@pytest.mark.parametrize("skip_arm64_test", [False, True])
 def test_universal2_testing(tmp_path, capfd, skip_arm64_test):
-    if utils.platform != 'macos':
-        pytest.skip('this test is only relevant to macos')
+    if utils.platform != "macos":
+        pytest.skip("this test is only relevant to macos")
    if get_xcode_version() < (12, 2):
-        pytest.skip('this test only works with Xcode 12.2 or greater')
-    if platform.machine() != 'x86_64':
-        pytest.skip('this test only works on x86_64')
+        pytest.skip("this test only works with Xcode 12.2 or greater")
+    if platform.machine() != "x86_64":
+        pytest.skip("this test only works on x86_64")

-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    basic_project.generate(project_dir)

-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_BUILD': 'cp39-*',
-        'CIBW_TEST_COMMAND': '''python -c "import platform; print('running tests on ' + platform.machine())"''',
-        'CIBW_ARCHS': 'universal2',
-        'CIBW_TEST_SKIP': '*_universal2:arm64' if skip_arm64_test else '',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_BUILD": "cp39-*",
+            "CIBW_TEST_COMMAND": '''python -c "import platform; print('running tests on ' + platform.machine())"''',
+            "CIBW_ARCHS": "universal2",
+            "CIBW_TEST_SKIP": "*_universal2:arm64" if skip_arm64_test else "",
+        },
+    )

    captured = capfd.readouterr()

-    if platform.machine() == 'x86_64':
-        assert 'running tests on x86_64' in captured.out
-        assert 'running tests on arm64' not in captured.out
+    if platform.machine() == "x86_64":
+        assert "running tests on x86_64" in captured.out
+        assert "running tests on arm64" not in captured.out

-        warning_message = 'While universal2 wheels can be built on x86_64, the arm64 part of them cannot currently be tested'
+        warning_message = "While universal2 wheels can be built on x86_64, the arm64 part of them cannot currently be tested"
        if skip_arm64_test:
            assert warning_message not in captured.err
        else:
            assert warning_message in captured.err

-    expected_wheels = [w for w in ALL_MACOS_WHEELS if 'cp39' in w and 'universal2' in w]
+    expected_wheels = [w for w in ALL_MACOS_WHEELS if "cp39" in w and "universal2" in w]

    assert set(actual_wheels) == set(expected_wheels)
@@ -7,7 +7,8 @@ from . import test_projects, utils

 # TODO: specify these at runtime according to manylinux_image
 project_with_manylinux_symbols = test_projects.new_c_project(
-    spam_c_top_level_add=textwrap.dedent(r'''
+    spam_c_top_level_add=textwrap.dedent(
+        r"""
        #include <malloc.h>
        #include <stdlib.h>
        #include <stdint.h>
@@ -20,8 +21,10 @@ project_with_manylinux_symbols = test_projects.new_c_project(
        #if !__GLIBC_PREREQ(2, 5)  /* manylinux1 is glibc 2.5 */
        #error "Must run on a glibc >= 2.5 linux environment"
        #endif
-    '''),
-    spam_c_function_add=textwrap.dedent(r'''
+        """
+    ),
+    spam_c_function_add=textwrap.dedent(
+        r"""
        #if defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 24)
            // nextupf is only available in manylinux_2_24+
            sts = (int)nextupf(0.0F);
@@ -32,44 +35,53 @@ project_with_manylinux_symbols = test_projects.new_c_project(
            // malloc_info is only available on manylinux2010+
            sts = malloc_info(0, stdout);
        #endif
-    '''),
+        """
+    ),
 )


-@pytest.mark.parametrize('manylinux_image', ['manylinux1', 'manylinux2010', 'manylinux2014', 'manylinux_2_24'])
+@pytest.mark.parametrize(
+    "manylinux_image", ["manylinux1", "manylinux2010", "manylinux2014", "manylinux_2_24"]
+)
 def test(manylinux_image, tmp_path):
-    if utils.platform != 'linux':
-        pytest.skip('the docker test is only relevant to the linux build')
-    elif platform.machine() not in ['x86_64', 'i686']:
-        if manylinux_image in ['manylinux1', 'manylinux2010']:
+    if utils.platform != "linux":
+        pytest.skip("the docker test is only relevant to the linux build")
+    elif platform.machine() not in ["x86_64", "i686"]:
+        if manylinux_image in ["manylinux1", "manylinux2010"]:
            pytest.skip("manylinux1 and 2010 doesn't exist for non-x86 architectures")

-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_manylinux_symbols.generate(project_dir)

    # build the wheels
    # CFLAGS environment variable is necessary to fail on 'malloc_info' (on manylinux1) during compilation/linking,
    # rather than when dynamically loading the Python
    add_env = {
-        'CIBW_ENVIRONMENT': 'CFLAGS="$CFLAGS -O0 -Werror=implicit-function-declaration"',
-        'CIBW_MANYLINUX_X86_64_IMAGE': manylinux_image,
-        'CIBW_MANYLINUX_I686_IMAGE': manylinux_image,
-        'CIBW_MANYLINUX_PYPY_X86_64_IMAGE': manylinux_image,
-        'CIBW_MANYLINUX_AARCH64_IMAGE': manylinux_image,
-        'CIBW_MANYLINUX_PPC64LE_IMAGE': manylinux_image,
-        'CIBW_MANYLINUX_S390X_IMAGE': manylinux_image,
+        "CIBW_ENVIRONMENT": 'CFLAGS="$CFLAGS -O0 -Werror=implicit-function-declaration"',
+        "CIBW_MANYLINUX_X86_64_IMAGE": manylinux_image,
+        "CIBW_MANYLINUX_I686_IMAGE": manylinux_image,
+        "CIBW_MANYLINUX_PYPY_X86_64_IMAGE": manylinux_image,
+        "CIBW_MANYLINUX_AARCH64_IMAGE": manylinux_image,
+        "CIBW_MANYLINUX_PPC64LE_IMAGE": manylinux_image,
+        "CIBW_MANYLINUX_S390X_IMAGE": manylinux_image,
+        "CIBW_MANYLINUX_PYPY_AARCH64_IMAGE": manylinux_image,
+        "CIBW_MANYLINUX_PYPY_I686_IMAGE": manylinux_image,
    }
-    if manylinux_image == 'manylinux1':
-        # We don't have a manylinux1 image for PyPy
-        add_env['CIBW_SKIP'] = 'pp*'
-    elif manylinux_image in {'manylinux2014', 'manylinux_2_24'}:
-        # We don't have a manylinux2014 / 'manylinux_2_24' image for PyPy (yet?)
-        add_env['CIBW_SKIP'] = 'cp27* pp*'  # Python 2.7 not available on manylinux2014 / 'manylinux_2_24'
+    if manylinux_image in {"manylinux1"}:
+        # We don't have a manylinux1 image for PyPy & CPython 3.10 and above
+        add_env["CIBW_SKIP"] = "pp* cp31*"
+
    actual_wheels = utils.cibuildwheel_run(project_dir, add_env=add_env)

-    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0', manylinux_versions=[manylinux_image])]
-    if manylinux_image in {'manylinux2014', 'manylinux_2_24'}:
-        expected_wheels = [w for w in expected_wheels if '-cp27' not in w]
-    if manylinux_image in {'manylinux1', 'manylinux2014', 'manylinux_2_24'}:
-        expected_wheels = [w for w in expected_wheels if '-pp' not in w]
+    platform_tag_map = {
+        "manylinux1": ["manylinux_2_5", "manylinux1"],
+        "manylinux2010": ["manylinux_2_12", "manylinux2010"],
+        "manylinux2014": ["manylinux_2_17", "manylinux2014"],
+    }
+    expected_wheels = utils.expected_wheels(
+        "spam", "0.1.0", manylinux_versions=platform_tag_map.get(manylinux_image, [manylinux_image])
+    )
+    if manylinux_image in {"manylinux1"}:
+        # remove PyPy & CPython 3.10 and above
+        expected_wheels = [w for w in expected_wheels if "-pp" not in w and "-cp31" not in w]
    assert set(actual_wheels) == set(expected_wheels)
@@ -1,4 +1,3 @@
-import os
 import textwrap

 from . import test_projects, utils
@@ -8,10 +7,7 @@ basic_project = test_projects.new_c_project(
        """
        # Will fail if PEP 518 does work
        import requests
-        if sys.version_info < (3, 6, 0):
-            assert requests.__version__ == "2.22.0", "Requests found but wrong version ({0})".format(requests.__version__)
-        else:
-            assert requests.__version__ == "2.23.0", "Requests found but wrong version ({0})".format(requests.__version__)
+        assert requests.__version__ == "2.23.0", "Requests found but wrong version ({0})".format(requests.__version__)

        # Just making sure environment is still set
        import os
@@ -29,29 +25,36 @@ requires = [
    "setuptools >= 42",
    "setuptools_scm[toml]>=4.1.2",
    "wheel",
-    "requests==2.22.0; python_version<'3.6'",
-    "requests==2.23.0; python_version>='3.6'"
+    "requests==2.23.0"
 ]

 build-backend = "setuptools.build_meta"
 """


-def test_pep518(tmp_path):
+def test_pep518(tmp_path, build_frontend_env):

    project_dir = tmp_path / "project"
    basic_project.generate(project_dir)

    # build the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir)
+    actual_wheels = utils.cibuildwheel_run(project_dir, add_env=build_frontend_env)

    # check that the expected wheels are produced
    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)

    # These checks ensure an extra file is not created when using custom
-    # workaround; see https://github.com/joerick/cibuildwheel/issues/421
+    # workaround; see https://github.com/pypa/cibuildwheel/issues/421
    assert not (project_dir / "42").exists()
    assert not (project_dir / "4.1.2").exists()

-    assert len(os.listdir(project_dir)) == len(basic_project.files)
+    # pypa/build creates a "build" folder & a "*.egg-info" folder for the wheel being built,
+    # this should be harmless so remove them
+    contents = [
+        item
+        for item in project_dir.iterdir()
+        if item.name != "build" and not item.name.endswith(".egg-info")
+    ]
+
+    assert len(contents) == len(basic_project.files)
@@ -1,2 +1,4 @@
-from .base import TestProject  # noqa
-from .c import new_c_project  # noqa
+from .base import TestProject
+from .c import new_c_project
+
+__all__ = ("TestProject", "new_c_project")
@@ -8,38 +8,42 @@ from pathlib import Path

 def main():
    parser = ArgumentParser(
-        prog="python -m test.test_projects",
-        description='Generate a test project to check it out'
+        prog="python -m test.test_projects", description="Generate a test project to check it out"
+    )
+    parser.add_argument(
+        "--open",
+        action="store_true",
+        help="Open the generated project in a file explorer",
+    )
+    parser.add_argument(
+        "PROJECT",
+        help="Python path to a project object. E.g. test.test_0_basic.basic_project",
+    )
+    parser.add_argument(
+        "OUTPUT",
+        nargs="?",
+        help="Path to output dir. If no dir is passed, a tempdir will be generated.",
    )
-    parser.add_argument('--open', action='store_true', help='''
-        Open the generated project in a file explorer
-    ''')
-    parser.add_argument('PROJECT', help='''
-        Python path to a project object. E.g. test.test_0_basic.basic_project
-    ''')
-    parser.add_argument('OUTPUT', nargs='?', help='''
-        Path to output dir. If no dir is passed, a tempdir will be generated.
-    ''')
    options = parser.parse_args()

-    module, _, name = options.PROJECT.rpartition('.')
+    module, _, name = options.PROJECT.rpartition(".")

    project = getattr(importlib.import_module(module), name)

    project_dir = Path(options.OUTPUT or tempfile.mkdtemp())
    project.generate(project_dir)

-    print('Project generated at', project_dir)
+    print("Project generated at", project_dir)
    print()

    if options.open:
-        if sys.platform == 'darwin':
-            subprocess.run(['open', '--', project_dir], check=True)
-        elif sys.platform == 'linux2':
-            subprocess.run(['xdg-open', '--', project_dir], check=True)
-        elif sys.platform == 'win32':
-            subprocess.run(['explorer', project_dir], check=True)
+        if sys.platform == "darwin":
+            subprocess.run(["open", "--", project_dir], check=True)
+        elif sys.platform == "linux2":
+            subprocess.run(["xdg-open", "--", project_dir], check=True)
+        elif sys.platform == "win32":
+            subprocess.run(["explorer", project_dir], check=True)


-if __name__ == '__main__':
+if __name__ == "__main__":
    main()
@@ -8,12 +8,13 @@ TemplateContext = Dict[str, Any]


 class TestProject:
-    '''
+    """
    An object that represents a project that can be built by cibuildwheel.
    Can be manipulated in tests by changing `files` and `template_context`.

    Write out to the filesystem using `generate`.
-    '''
+    """
+
    __test__ = False  # Have pytest ignore this class on `from .test_projects import TestProject`

    files: FilesDict
@@ -28,7 +29,7 @@ class TestProject:
            file_path = path / filename
            file_path.parent.mkdir(parents=True, exist_ok=True)

-            with file_path.open('w', encoding='utf8') as f:
+            with file_path.open("w", encoding="utf8") as f:
                if isinstance(content, jinja2.Template):
                    content = content.render(self.template_context)

@@ -2,7 +2,7 @@ import jinja2

 from .base import TestProject

-SPAM_C_TEMPLATE = r'''
+SPAM_C_TEMPLATE = r"""
 #include <Python.h>

 {{ spam_c_top_level_add }}
@@ -24,42 +24,22 @@ spam_system(PyObject *self, PyObject *args)
 }

 /* Module initialization */
-
-#if PY_MAJOR_VERSION >= 3
-    #define MOD_INIT(name) PyMODINIT_FUNC PyInit_##name(void)
-    #define MOD_DEF(m, name, doc, methods, module_state_size) \
-        static struct PyModuleDef moduledef = { \
-            PyModuleDef_HEAD_INIT, name, doc, module_state_size, methods, }; \
-        m = PyModule_Create(&moduledef);
-    #define MOD_RETURN(m) return m;
-#else
-    #define MOD_INIT(name) PyMODINIT_FUNC init##name(void)
-    #define MOD_DEF(m, name, doc, methods, module_state_size) \
-        m = Py_InitModule3(name, methods, doc);
-    #define MOD_RETURN(m) return;
-#endif
-
 static PyMethodDef module_methods[] = {
    {"system", (PyCFunction)spam_system, METH_VARARGS,
     "Execute a shell command."},
    {NULL}  /* Sentinel */
 };

-MOD_INIT(spam)
+PyMODINIT_FUNC PyInit_spam(void)
 {
-    PyObject* m;
-
-    MOD_DEF(m,
-            "spam",
-            "Example module",
-            module_methods,
-            -1)
-
-    MOD_RETURN(m)
+    static struct PyModuleDef moduledef = {
+        PyModuleDef_HEAD_INIT, "spam", "Example module", -1, module_methods,
+    };
+    return PyModule_Create(&moduledef);
 }
-'''
+"""

-SETUP_PY_TEMPLATE = r'''
+SETUP_PY_TEMPLATE = r"""
 import sys
 from setuptools import setup, Extension

@@ -77,33 +57,43 @@ setup(
    )],
    {{ setup_py_setup_args_add | indent(4) }}
 )
-'''
+"""

-SETUP_CFG_TEMPLATE = r'''
+SETUP_CFG_TEMPLATE = r"""
 [metadata]
 name = spam
 version = 0.1.0

 {{ setup_cfg_add }}
-'''
+"""


-def new_c_project(*, spam_c_top_level_add='', spam_c_function_add='', setup_py_add='',
-                  setup_py_setup_args_add='', setup_cfg_add=''):
+def new_c_project(
+    *,
+    spam_c_top_level_add="",
+    spam_c_function_add="",
+    setup_py_add="",
+    setup_py_setup_args_add="",
+    setup_cfg_add="",
+):
    project = TestProject()

-    project.files.update({
-        'spam.c': jinja2.Template(SPAM_C_TEMPLATE),
-        'setup.py': jinja2.Template(SETUP_PY_TEMPLATE),
-        'setup.cfg': jinja2.Template(SETUP_CFG_TEMPLATE),
-    })
+    project.files.update(
+        {
+            "spam.c": jinja2.Template(SPAM_C_TEMPLATE),
+            "setup.py": jinja2.Template(SETUP_PY_TEMPLATE),
+            "setup.cfg": jinja2.Template(SETUP_CFG_TEMPLATE),
+        }
+    )

-    project.template_context.update({
-        'spam_c_top_level_add': spam_c_top_level_add,
-        'spam_c_function_add': spam_c_function_add,
-        'setup_py_add': setup_py_add,
-        'setup_py_setup_args_add': setup_py_setup_args_add,
-        'setup_cfg_add': setup_cfg_add,
-    })
+    project.template_context.update(
+        {
+            "spam_c_top_level_add": spam_c_top_level_add,
+            "spam_c_function_add": spam_c_function_add,
+            "setup_py_add": setup_py_add,
+            "setup_py_setup_args_add": setup_py_setup_args_add,
+            "setup_cfg_add": setup_cfg_add,
+        }
+    )

    return project
@@ -6,7 +6,9 @@ import pytest
 from . import utils

 pure_python_project = test_projects.TestProject()
-pure_python_project.files['setup.py'] = '''
+pure_python_project.files[
+    "setup.py"
+] = """
 from setuptools import Extension, setup

 setup(
@@ -14,25 +16,27 @@ setup(
    py_modules=['spam'],
    version="0.1.0",
 )
-'''
+"""

-pure_python_project.files['spam.py'] = '''
+pure_python_project.files[
+    "spam.py"
+] = """
 def a_function():
    pass
-'''
+"""


 def test(tmp_path, capfd):
    # this test checks that if a pure wheel is generated, the build should
    # fail.
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    pure_python_project.generate(project_dir)

    with pytest.raises(subprocess.CalledProcessError):
        actual_wheels = utils.cibuildwheel_run(project_dir)
-        print('produced wheels:', actual_wheels)
+        print("produced wheels:", actual_wheels)

    captured = capfd.readouterr()
-    print('out', captured.out)
-    print('err', captured.err)
+    print("out", captured.out)
+    print("err", captured.err)
    assert "Build failed because a pure Python wheel was generated" in captured.err
@@ -3,29 +3,28 @@ import textwrap
 from . import test_projects, utils

 project_with_ssl_tests = test_projects.new_c_project(
-    setup_py_add=textwrap.dedent(r'''
+    setup_py_add=textwrap.dedent(
+        r"""
        import ssl

-        if sys.version_info[0] == 2:
-            from urllib2 import urlopen
-        else:
-            from urllib.request import urlopen
+        from urllib.request import urlopen

        context = ssl.SSLContext(ssl.PROTOCOL_TLSv1_2)
        data = urlopen("https://www.nist.gov", context=context)
-        data = urlopen("https://raw.githubusercontent.com/joerick/cibuildwheel/master/CI.md", context=context)
-        data = urlopen("https://raw.githubusercontent.com/joerick/cibuildwheel/master/CI.md")
-    ''')
+        data = urlopen("https://raw.githubusercontent.com/pypa/cibuildwheel/main/CI.md", context=context)
+        data = urlopen("https://raw.githubusercontent.com/pypa/cibuildwheel/main/CI.md")
+        """
+    )
 )


 def test(tmp_path):
    # this test checks that SSL is working in the build environment using
    # some checks in setup.py.
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_ssl_tests.generate(project_dir)

    actual_wheels = utils.cibuildwheel_run(project_dir)

-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)
@@ -8,11 +8,13 @@ from .test_projects.c import SPAM_C_TEMPLATE

 subdir_package_project = TestProject()

-subdir_package_project.files['src/spam/spam.c'] = jinja2.Template(SPAM_C_TEMPLATE)
-subdir_package_project.template_context['spam_c_top_level_add'] = ''
-subdir_package_project.template_context['spam_c_function_add'] = ''
+subdir_package_project.files["src/spam/spam.c"] = jinja2.Template(SPAM_C_TEMPLATE)
+subdir_package_project.template_context["spam_c_top_level_add"] = ""
+subdir_package_project.template_context["spam_c_function_add"] = ""

-subdir_package_project.files['src/spam/setup.py'] = r'''
+subdir_package_project.files[
+    "src/spam/setup.py"
+] = r"""
 from setuptools import Extension, setup

 setup(
@@ -20,33 +22,40 @@ setup(
    ext_modules=[Extension('spam', sources=['spam.c'])],
    version="0.1.0",
 )
-'''
+"""

-subdir_package_project.files['src/spam/test/run_tests.py'] = r'''
+subdir_package_project.files[
+    "src/spam/test/run_tests.py"
+] = r"""
 print('run_tests.py executed!')
-'''
+"""

-subdir_package_project.files['bin/before_build.py'] = r'''
+subdir_package_project.files[
+    "bin/before_build.py"
+] = r"""
 print('before_build.py executed!')
-'''
+"""


 def test(capfd, tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    subdir_package_project.generate(project_dir)

-    package_dir = Path('src', 'spam')
+    package_dir = Path("src", "spam")
    # build the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, package_dir=package_dir, add_env={
-        'CIBW_BEFORE_BUILD': 'python {project}/bin/before_build.py',
-        'CIBW_TEST_COMMAND': 'python {package}/test/run_tests.py',
-        # this shouldn't depend on the version of python, so build only CPython 3.6
-        'CIBW_BUILD': 'cp36-*',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        package_dir=package_dir,
+        add_env={
+            "CIBW_BEFORE_BUILD": "python {project}/bin/before_build.py",
+            "CIBW_TEST_COMMAND": "python {package}/test/run_tests.py",
+            # this shouldn't depend on the version of python, so build only CPython 3.6
+            "CIBW_BUILD": "cp36-*",
+        },
+    )

    # check that the expected wheels are produced
-    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
-                       if 'cp36' in w]
+    expected_wheels = [w for w in utils.expected_wheels("spam", "0.1.0") if "cp36" in w]
    assert set(actual_wheels) == set(expected_wheels)

    captured = capfd.readouterr()
@@ -7,13 +7,17 @@ import pytest
 from . import test_projects, utils

 project_with_a_test = test_projects.new_c_project(
-    setup_cfg_add=textwrap.dedent(r'''
+    setup_cfg_add=textwrap.dedent(
+        r"""
        [options.extras_require]
-        test = nose
-    ''')
+        test = pytest
+        """
+    )
 )

-project_with_a_test.files['test/spam_test.py'] = r'''
+project_with_a_test.files[
+    "test/spam_test.py"
+] = r'''
 import os
 import platform
 import sys
@@ -48,8 +52,7 @@ class TestSpam(TestCase):
        # sys.prefix is different from sys.base_prefix when running a virtualenv
        # See https://docs.python.org/3/library/venv.html, which virtualenv seems
        # to honor in recent releases
-        # Python 2 doesn't have sys.base_prefix by default
-        if not hasattr(sys, 'base_prefix') or sys.prefix == sys.base_prefix:
+        if sys.prefix == sys.base_prefix:
            self.fail("Not running in a virtualenv")

        self.assertTrue(path_contains(sys.prefix, sys.executable))
@@ -63,73 +66,81 @@ class TestSpam(TestCase):
        bits = struct.calcsize("P") * 8
        if bits == 32:
            self.assertEqual(platform.machine(), "i686")
-
-    def test_time_to_remove_the_pypy_venv_patch(self):
-        if sys.platform == "darwin":
-            assert not hasattr(sys, "pypy_version_info") or sys.pypy_version_info < (7,3,4)
 '''


 def test(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_a_test.generate(project_dir)

    # build and test the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_TEST_REQUIRES': 'nose',
-        # the 'false ||' bit is to ensure this command runs in a shell on
-        # mac/linux.
-        'CIBW_TEST_COMMAND': 'false || nosetests {project}/test',
-        'CIBW_TEST_COMMAND_WINDOWS': 'COLOR 00 || nosetests {project}/test',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_TEST_REQUIRES": "pytest",
+            # the 'false ||' bit is to ensure this command runs in a shell on
+            # mac/linux.
+            "CIBW_TEST_COMMAND": "false || pytest {project}/test",
+            "CIBW_TEST_COMMAND_WINDOWS": "COLOR 00 || pytest {project}/test",
+        },
+    )

    # also check that we got the right wheels
-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)


 def test_extras_require(tmp_path):
-    project_dir = tmp_path / 'project'
+    project_dir = tmp_path / "project"
    project_with_a_test.generate(project_dir)

    # build and test the wheels
-    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
-        'CIBW_TEST_EXTRAS': 'test',
-        # the 'false ||' bit is to ensure this command runs in a shell on
-        # mac/linux.
-        'CIBW_TEST_COMMAND': 'false || nosetests {project}/test',
-        'CIBW_TEST_COMMAND_WINDOWS': 'COLOR 00 || nosetests {project}/test',
-    })
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_TEST_EXTRAS": "test",
+            # the 'false ||' bit is to ensure this command runs in a shell on
+            # mac/linux.
+            "CIBW_TEST_COMMAND": "false || pytest {project}/test",
+            "CIBW_TEST_COMMAND_WINDOWS": "COLOR 00 || pytest {project}/test",
+        },
+    )

    # also check that we got the right wheels
-    expected_wheels = utils.expected_wheels('spam', '0.1.0')
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
    assert set(actual_wheels) == set(expected_wheels)


 project_with_a_failing_test = test_projects.new_c_project()
-project_with_a_failing_test.files['test/spam_test.py'] = r'''
+project_with_a_failing_test.files[
+    "test/spam_test.py"
+] = r"""
 from unittest import TestCase

 class TestSpam(TestCase):
    def test_something(self):
        self.fail('this test is supposed to fail')
-'''
+"""


 def test_failing_test(tmp_path):
    """Ensure a failing test causes cibuildwheel to error out and exit"""
-    project_dir = tmp_path / 'project'
-    output_dir = tmp_path / 'output'
+    project_dir = tmp_path / "project"
+    output_dir = tmp_path / "output"
    project_with_a_failing_test.generate(project_dir)

    with pytest.raises(subprocess.CalledProcessError):
-        utils.cibuildwheel_run(project_dir, output_dir=output_dir, add_env={
-            'CIBW_TEST_REQUIRES': 'nose',
-            'CIBW_TEST_COMMAND': 'nosetests {project}/test',
-            # manylinux1 has a version of bash that's been shown to have
-            # problems with this, so let's check that.
-            'CIBW_MANYLINUX_I686_IMAGE': 'manylinux1',
-            'CIBW_MANYLINUX_X86_64_IMAGE': 'manylinux1',
-        })
+        utils.cibuildwheel_run(
+            project_dir,
+            output_dir=output_dir,
+            add_env={
+                "CIBW_TEST_REQUIRES": "nose",
+                "CIBW_TEST_COMMAND": "nosetests {project}/test",
+                # manylinux1 has a version of bash that's been shown to have
+                # problems with this, so let's check that.
+                "CIBW_MANYLINUX_I686_IMAGE": "manylinux1",
+                "CIBW_MANYLINUX_X86_64_IMAGE": "manylinux1",
+            },
+        )

    assert len(os.listdir(output_dir)) == 0
--- a/Show More
+++ b/Show More