feat: add support for building iOS wheels. (#2286)

* Add support for building iOS wheels.

* Replace use of system() in test binary module.

* Restored the 'minimal' approach of the minimal examples.

* Split out platform details into standalone pages, and expand iOS platform details.

* More doc corrections.

* Bump support package to include fix for python/cpython#130292

* Ensure iOS tests are all run on the same xdist worker.

* More iOS documentation tweaks.

* Factor out common xcode version test utility.

* Simplify iOS to a single platform with an expanded interpretation of arch.

* I guess I should update the iOS tests as well...

* Additional safety for missing iOS test output.

* Remove DYLD_LIBRARY_PATH from the iOS environment.

* Make test-sources mandatory for iOS builds.

* Updates and clarifications to documentation.

* Clarify what a slice is.

* Normalize use of underscores in platform name.

* Modify auto target to be matching CPU only.

* Use consistent ordering of platforms in examples.

* Use consistent naming in iOS archiectures.

* Placate the linter.

* Miscellaneous cleanups picked up by @joerick's review.

* Correct the list of expected wheels.

* Correct which 'native' we're actually checking.

* Correct the docs links so they're all relative.

* Correct the identification of free threaded builds.

* Use target instead of host to describe the platform we're building for.

* Rework iOS test to remove issue with log completeness.

* Convert errors to FatalError

Co-authored-by: Matthieu Darbois <mayeut@users.noreply.github.com>
Co-authored-by: Joe Rickerby <joerick@mac.com>

* Removed a repeated check for a valid python.

* Update bin/update_pythons.py to update iOS support packages.

* Document that iOS CI is available on other platforms.

* Restore a comment needed for some platforms.

* Small cleanups identified in code review

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

* Simplify logic to appease linter.

* Modify dependency constraint handling to use new API.

* Cosmetic change to trigger a CI rebuild.

---------

Co-authored-by: Matthieu Darbois <mayeut@users.noreply.github.com>
Co-authored-by: Joe Rickerby <joerick@mac.com>

test/test_macos_archs.py

@@ -1,5 +1,4 @@
 import platform
-import subprocess
 
 import pytest
 
@@ -20,24 +19,10 @@ ALL_MACOS_WHEELS = {
 DEPLOYMENT_TARGET_TOO_LOW_WARNING = "Bumping MACOSX_DEPLOYMENT_TARGET"
 
 
-def get_xcode_version() -> tuple[int, int]:
-    output = subprocess.run(
-        ["xcodebuild", "-version"],
-        text=True,
-        check=True,
-        stdout=subprocess.PIPE,
-    ).stdout
-    lines = output.splitlines()
-    _, version_str = lines[0].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 get_xcode_version() < (12, 2):
+    if utils.get_xcode_version() < (12, 2):
         pytest.skip("this test only works with Xcode 12.2 or greater")
 
     project_dir = tmp_path / "project"
@@ -71,7 +56,7 @@ def test_cross_compiled_build(tmp_path):
 def test_cross_compiled_test(tmp_path, capfd, build_universal2, test_config):
     if utils.platform != "macos":
         pytest.skip("this test is only relevant to macos")
-    if get_xcode_version() < (12, 2):
+    if utils.get_xcode_version() < (12, 2):
         pytest.skip("this test only works with Xcode 12.2 or greater")
 
     project_dir = tmp_path / "project"
@@ -153,7 +138,7 @@ def test_deployment_target_warning_is_firing(tmp_path, capfd):
 def test_universal2_testing_on_x86_64(tmp_path, capfd, skip_arm64_test):
     if utils.platform != "macos":
         pytest.skip("this test is only relevant to macos")
-    if get_xcode_version() < (12, 2):
+    if utils.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")
@@ -223,7 +208,7 @@ def test_universal2_testing_on_arm64(build_frontend_env, tmp_path, capfd):
 def test_cp38_arm64_testing(tmp_path, capfd, request):
     if utils.platform != "macos":
         pytest.skip("this test is only relevant to macos")
-    if get_xcode_version() < (12, 2):
+    if utils.get_xcode_version() < (12, 2):
         pytest.skip("this test only works with Xcode 12.2 or greater")
     if platform.machine() != "arm64":
         pytest.skip("this test only works on arm64")