feat: remove 32-bit linux from auto arch, fix auto32 on linux aarch64 (#2458)

* feat: remove 32-bit linux from auto arch, fix auto32 on linux aarch64

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* Apply suggestions from code review

Co-authored-by: Joe Rickerby <joerick@mac.com>

* Update cibuildwheel/architecture.py

---------

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
Co-authored-by: Joe Rickerby <joerick@mac.com>

cibuildwheel/architecture.py

@@ -75,24 +75,24 @@ class Architecture(StrEnum):
     def parse_config(config: str, platform: PlatformName) -> "set[Architecture]":
         result = set()
         for arch_str in re.split(r"[\s,]+", config):
-            if arch_str == "auto":
+            match arch_str:
-                result |= Architecture.auto_archs(platform=platform)
+                case "auto":
-            elif arch_str == "native":
+                    result |= Architecture.auto_archs(platform=platform)
-                native_arch = Architecture.native_arch(platform=platform)
+                case "native":
-                if native_arch:
+                    if native_arch := Architecture.native_arch(platform=platform):
-                    result.add(native_arch)
+                        result.add(native_arch)
-            elif arch_str == "all":
+                case "all":
-                result |= Architecture.all_archs(platform=platform)
+                    result |= Architecture.all_archs(platform=platform)
-            elif arch_str == "auto64":
+                case "auto64":
-                result |= Architecture.bitness_archs(platform=platform, bitness="64")
+                    result |= Architecture.bitness_archs(platform=platform, bitness="64")
-            elif arch_str == "auto32":
+                case "auto32":
-                result |= Architecture.bitness_archs(platform=platform, bitness="32")
+                    result |= Architecture.bitness_archs(platform=platform, bitness="32")
-            else:
+                case _:
-                try:
+                    try:
-                    result.add(Architecture(arch_str))
+                        result.add(Architecture(arch_str))
-                except ValueError as e:
+                    except ValueError as e:
-                    msg = f"Invalid architecture '{arch_str}'"
+                        msg = f"Invalid architecture '{arch_str}'"
-                    raise errors.ConfigurationError(msg) from e
+                        raise errors.ConfigurationError(msg) from e
         return result
 
     @staticmethod
@@ -142,19 +142,12 @@ class Architecture(StrEnum):
             return set()  # can't build anything on this platform
         result = {native_arch}
 
-        if platform == "linux":
+        match platform:
-            if Architecture.x86_64 in result:
+            case "windows" if Architecture.AMD64 in result:
-                # x86_64 machines can run i686 containers
+                result.add(Architecture.x86)
-                result.add(Architecture.i686)
+            case "ios" if native_arch == Architecture.arm64_iphonesimulator:
-            elif Architecture.aarch64 in result and _check_aarch32_el0():
+                # Also build the device wheel if we're on ARM64.
-                result.add(Architecture.armv7l)
+                result.add(Architecture.arm64_iphoneos)
-
-        elif platform == "windows" and Architecture.AMD64 in result:
-            result.add(Architecture.x86)
-
-        elif platform == "ios" and native_arch == Architecture.arm64_iphonesimulator:
-            # Also build the device wheel if we're on ARM64.
-            result.add(Architecture.arm64_iphoneos)
 
         return result
 
@@ -183,14 +176,35 @@ class Architecture(StrEnum):
 
     @staticmethod
     def bitness_archs(platform: PlatformName, bitness: Literal["64", "32"]) -> "set[Architecture]":
-        archs_32 = {Architecture.i686, Architecture.x86, Architecture.armv7l}
+        # This map maps 64-bit architectures to their 32-bit equivalents.
-        auto_archs = Architecture.auto_archs(platform)
+        archs_map = {
+            Architecture.x86_64: Architecture.i686,
+            Architecture.AMD64: Architecture.x86,
+            Architecture.aarch64: Architecture.armv7l,
+        }
+        native_arch = Architecture.native_arch(platform)
 
-        if bitness == "64":
+        if native_arch is None:
-            return auto_archs - archs_32
+            return set()  # can't build anything on this platform
-        if bitness == "32":
+
-            return auto_archs & archs_32
+        if native_arch == Architecture.wasm32:
-        typing.assert_never(bitness)
+            return {native_arch} if bitness == "32" else set()
+
+        match bitness:
+            case "64":
+                return {native_arch} if native_arch not in archs_map.values() else set()
+            case "32":
+                if native_arch in archs_map.values():
+                    return {native_arch}
+                elif native_arch in archs_map and platform in {"linux", "windows"}:
+                    if native_arch == Architecture.aarch64 and not _check_aarch32_el0():
+                        # If we're on aarch64, skip if we cannot build armv7l wheels.
+                        return set()
+                    return {archs_map[native_arch]}
+                else:
+                    return set()
+            case _:
+                typing.assert_never(bitness)
 
 
 def allowed_architectures_check(

docs/options.md

@@ -191,10 +191,10 @@ Options:
 - Windows: `AMD64` `x86` `ARM64`
 - Pyodide: `wasm32`
 - iOS: `arm64_iphoneos` `arm64_iphonesimulator` `x86_64_iphonesimulator`
-- `auto`: The default archs for your machine - see the table below.
+- `auto`: The recommended archs for your machine - see the table below.
-    - `auto64`: Just the 64-bit auto archs
+- `auto64`: The 64-bit arch(s) supported by your machine (includes device and simulator for iOS)
-    - `auto32`: Just the 32-bit auto archs
+- `auto32`: The 32-bit arch supported by your machine
-- `native`: the native arch of the build machine - Matches [`platform.machine()`](https://docs.python.org/3/library/platform.html#platform.machine).
+- `native`: the native arch of the build machine - matches [`platform.machine()`](https://docs.python.org/3/library/platform.html#platform.machine).
 - `all` : expands to all the architectures supported on this OS. You may want
   to use [`build`](#build-skip) with this option to target specific
   architectures via build selectors.
@@ -205,16 +205,34 @@ Default: `auto`
 
 | Runner | `native` | `auto` | `auto64` | `auto32` |
 |---|---|---|---|---|
-| Linux / Intel | `x86_64` | `x86_64` `i686` | `x86_64` | `i686` |
+| Linux / Intel 64-bit | `x86_64` | `x86_64` | `x86_64` | `i686` |
-| Windows / Intel | `AMD64` | `AMD64` `x86` | `AMD64` | `x86` |
+| Linux / Intel 32-bit | `i686` | `i686` |  | `i686` |
+| Linux / Arm 64-bit | `aarch64` | `aarch64` | `aarch64` | `armv7l`¹ |
+| Linux / Arm 32-bit | `armv7l` | `armv7l` | | `armv7l` |
+| Windows / Intel 64-bit | `AMD64` | `AMD64` `x86` | `AMD64` | `x86` |
+| Windows / Intel 32-bit | `x86` | `x86` | | `x86` |
 | Windows / ARM64 | `ARM64` | `ARM64` | `ARM64` | |
 | macOS / Intel | `x86_64` | `x86_64` | `x86_64` |  |
 | macOS / Apple Silicon | `arm64` | `arm64` | `arm64` |  |
 | iOS on macOS / Intel | `x86_64_iphonesimulator` | `x86_64_iphonesimulator` | `x86_64_iphonesimulator` |  |
 | iOS on macOS / Apple Silicon | `arm64_iphonesimulator` | `arm64_iphoneos` `arm64_iphonesimulator` | `arm64_iphoneos` `arm64_iphonesimulator` |
 
+¹: This will only be included if the runner supports it.
+
 If not listed above, `auto` is the same as `native`.
 
+!!! warning
+    The `auto` option only includes 32-bit architectures if they are
+    commonly built. `cibuildwheel` 3.0 removed 32-bit Linux builds from `auto`,
+    and a future release may remove 32-bit Windows builds from `auto` as well.
+    If you know you need them, please include `auto32`. Note that modern
+    manylinux image do not support 32-bit builds. If you want to avoid 32-bit
+    Windows builds today, feel free to use `auto64`.
+
+!!! note
+    Pyodide currently ignores the architecture setting, as it always builds for
+    `wasm32`.
+
 [setup-qemu-action]: https://github.com/docker/setup-qemu-action
 [binfmt]: https://hub.docker.com/r/tonistiigi/binfmt
 
@@ -238,6 +256,10 @@ This option can also be set using the [command-line option](#command-line)
     # On an Linux Intel runner with qemu installed, build Intel and ARM wheels
     [tool.cibuildwheel.linux]
     archs = ["auto", "aarch64"]
+
+    # Build all 32-bit and 64-bit wheels natively buildable on the image
+    [tool.cibuildwheel]
+    archs = ["auto64", "auto32"]
     ```
 
 !!! tab examples "Environment variables"
@@ -250,12 +272,13 @@ This option can also be set using the [command-line option](#command-line)
 
     # On an Linux Intel runner with qemu installed, build Intel and ARM wheels
     CIBW_ARCHS_LINUX: "auto aarch64"
+
+    # Build all 32-bit and 64-bit wheels natively buildable on the image
+    CIBW_ARCHS: "auto64 auto32"
     ```
 
     Separate multiple archs with a space.
 
-
-
     It is generally recommended to use the environment variable or
     command-line option for Linux, as selecting archs often depends
     on your specific runner having qemu installed.

test/utils.py

@@ -175,6 +175,7 @@ def expected_wheels(
     include_universal2: bool = False,
     single_python: bool = False,
     single_arch: bool = False,
+    full_auto: bool = False,
 ) -> list[str]:
     """
     Returns the expected wheels from a run of cibuildwheel.
@@ -194,7 +195,7 @@ def expected_wheels(
 
     architectures = [machine_arch]
     if not single_arch:
-        if platform == "linux":
+        if platform == "linux" and full_auto:
             if machine_arch == "x86_64":
                 architectures.append("i686")
             elif (

unit_test/architecture_test.py

@@ -34,8 +34,8 @@ def test_arch_auto(platform_machine):
     arch_set = Architecture.auto_archs("linux")
     expected = {
         "32": {Architecture.i686},
-        "64": {Architecture.x86_64, Architecture.i686},
+        "64": {Architecture.x86_64},
-        "arm": {Architecture.aarch64, Architecture.armv7l},
+        "arm": {Architecture.aarch64},
     }
     assert arch_set == expected[machine_name]
 
@@ -94,5 +94,24 @@ def test_arch_auto_no_aarch32(monkeypatch):
     arch_set = Architecture.parse_config("auto64", "linux")
     assert arch_set == {Architecture.aarch64}
 
+    monkeypatch.setattr(cibuildwheel.architecture, "_check_aarch32_el0", lambda: True)
     arch_set = Architecture.parse_config("auto32", "linux")
-    assert len(arch_set) == 0
+    assert arch_set == {Architecture.armv7l}
+
+    monkeypatch.setattr(cibuildwheel.architecture, "_check_aarch32_el0", lambda: False)
+    arch_set = Architecture.parse_config("auto32", "linux")
+    assert arch_set == set()
+
+
+def test_arch_native_on_ios(monkeypatch):
+    monkeypatch.setattr(sys, "platform", "darwin")
+    monkeypatch.setattr(platform_module, "machine", lambda: "arm64")
+    arch_set = Architecture.parse_config("native", platform="ios")
+    assert arch_set == {Architecture.arm64_iphonesimulator}
+
+
+def test_arch_auto_on_ios(monkeypatch):
+    monkeypatch.setattr(sys, "platform", "darwin")
+    monkeypatch.setattr(platform_module, "machine", lambda: "arm64")
+    arch_set = Architecture.parse_config("auto", platform="ios")
+    assert arch_set == {Architecture.arm64_iphonesimulator, Architecture.arm64_iphoneos}

unit_test/main_tests/main_platform_test.py

@@ -79,7 +79,7 @@ def test_archs_default(platform, intercepted_build_args):
     options = intercepted_build_args.args[0]
 
     if platform == "linux":
-        assert options.globals.architectures == {Architecture.x86_64, Architecture.i686}
+        assert options.globals.architectures == {Architecture.x86_64}
     elif platform == "windows":
         assert options.globals.architectures == {Architecture.AMD64, Architecture.x86}
     else:

unit_test/option_prepare_test.py

@@ -51,6 +51,7 @@ def mock_build_container(monkeypatch):
 @pytest.mark.usefixtures("mock_build_container", "fake_package_dir")
 def test_build_default_launches(monkeypatch):
     monkeypatch.setattr(sys, "argv", [*sys.argv, "--platform=linux"])
+    monkeypatch.setenv("CIBW_ARCHS", "auto64 auto32")
     monkeypatch.delenv("CIBW_ENABLE", raising=False)
 
     main()
@@ -105,6 +106,7 @@ def test_build_with_override_launches(monkeypatch, tmp_path):
 manylinux-x86_64-image = "manylinux_2_28"
 musllinux-x86_64-image = "musllinux_1_2"
 enable = ["pypy", "pypy-eol", "graalpy", "cpython-freethreading"]
+archs = ["auto64", "auto32"]
 
 # Before Python 3.10, use manylinux2014
 [[tool.cibuildwheel.overrides]]

unit_test/options_test.py

@@ -25,6 +25,7 @@ PYPROJECT_1 = """
 [tool.cibuildwheel]
 build = ["cp38-*", "cp313-*"]
 skip = ["*musllinux*"]
+archs = ["auto64", "auto32"]
 environment = {FOO="BAR"}
 
 test-command = "pyproject"