feat: wheel_tag & support for conda's CMAKE_SYSTEM_PROCESSOR (#207)

A bit of refactoring.

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

src/scikit_build_core/build/wheel.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import dataclasses
+import os
 import shutil
 import sys
 import tempfile
@@ -13,7 +14,7 @@
 from .. import __version__
 from .._compat import tomllib
 from .._logging import logger, rich_print
-from ..builder.builder import Builder
+from ..builder.builder import Builder, archs_to_tags, get_archs
 from ..builder.wheel_tag import WheelTag
 from ..cmake import CMake, CMaker
 from ..settings.skbuild_read_settings import SettingsReader
@@ -108,9 +109,18 @@ def _build_wheel_impl(
         build_tmp_folder = Path(tmpdir)
         wheel_dir = build_tmp_folder / "wheel"
 
+        tags = WheelTag.compute_best(
+            archs_to_tags(get_archs(os.environ)),
+            settings.wheel.py_api,
+            expand_macos=settings.wheel.expand_macos_universal_tags,
+        )
+
         # A build dir can be specified, otherwise use a temporary directory
         build_dir = (
-            Path(settings.build_dir.format(cache_tag=sys.implementation.cache_tag))
+            Path(
+                settings.build_dir.format(cache_tag=sys.implementation.cache_tag),
+                wheel_tag=str(tags),
+            )
             if settings.build_dir
             else build_tmp_folder / "build"
         )
@@ -153,12 +163,6 @@ def _build_wheel_impl(
             config=config,
         )
 
-        tags = WheelTag.compute_best(
-            builder.get_arch_tags(),
-            settings.wheel.py_api,
-            expand_macos=settings.wheel.expand_macos_universal_tags,
-        )
-
         if wheel_directory is None:
             if metadata_directory is None:
                 msg = "metadata_directory must be specified if wheel_directory is None"

src/scikit_build_core/builder/builder.py

@@ -4,6 +4,7 @@
 import re
 import sys
 import sysconfig
+from collections.abc import Sequence
 from pathlib import Path
 from typing import Mapping
 
@@ -17,7 +18,7 @@
 from .generator import set_environment_for_gen
 from .sysconfig import get_platform, get_python_include_dir, get_python_library
 
-__all__: list[str] = ["Builder"]
+__all__: list[str] = ["Builder", "get_archs", "archs_to_tags"]
 
 DIR = Path(__file__).parent.resolve()
 
@@ -26,45 +27,53 @@ def __dir__() -> list[str]:
     return __all__
 
 
-@dataclasses.dataclass
-class Builder:
-    settings: ScikitBuildSettings
-    config: CMaker
+# TODO: cross-compile support for other platforms
+def get_archs(env: Mapping[str, str], cmake_args: Sequence[str] = ()) -> list[str]:
+    """
+    Takes macOS platform settings and returns a list of platforms.
 
-    # TODO: cross-compile support for other platforms
-    def get_archs(self) -> list[str]:
-        """
-        Takes macOS platform settings and returns a list of platforms.
+    Example (macOS):
+        ARCHFLAGS="-arch x86_64" -> ["x86_64"]
+        ARCHFLAGS="-arch x86_64 -arch arm64" -> ["x86_64", "arm64"]
 
-        Example (macOS):
-            ARCHFLAGS="-arch x86_64" -> ["x86_64"]
-            ARCHFLAGS="-arch x86_64 -arch arm64" -> ["x86_64", "arm64"]
+    Returns an empty list otherwise or if ARCHFLAGS is not set.
+    """
 
-        Returns an empty list otherwise or if ARCHFLAGS is not set.
-        """
+    if sys.platform.startswith("darwin"):
+        for cmake_arg in cmake_args:
+            if "CMAKE_SYSTEM_PROCESSOR" in cmake_arg:
+                return [cmake_arg.split("=")[1]]
+        archs = re.findall(r"-arch (\S+)", env.get("ARCHFLAGS", ""))
+        return archs
+    if sys.platform.startswith("win") and get_platform(env) == "win-arm64":
+        return ["win_arm64"]
+
+    return []
+
+
+def archs_to_tags(archs: list[str]) -> list[str]:
+    """
+    Convert a list of architectures to a list of tags (e.g. "universal2").
+    """
+    if sys.platform.startswith("darwin") and set(archs) == {"arm64", "x86_64"}:
+        return ["universal2"]
+    return archs
 
-        if sys.platform.startswith("darwin"):
-            archs = re.findall(r"-arch (\S+)", self.config.env.get("ARCHFLAGS", ""))
-            return archs
-        if (
-            sys.platform.startswith("win")
-            and get_platform(self.config.env) == "win-arm64"
-        ):
-            return ["win_arm64"]
 
-        return []
+@dataclasses.dataclass
+class Builder:
+    settings: ScikitBuildSettings
+    config: CMaker
 
-    def get_arch_tags(self) -> list[str]:
+    def get_cmake_args(self) -> list[str]:
         """
-        This function returns tags suitable for use in wheels. The main
-        difference between this method and get_archs() is that this returns
-        universal2 instead of separate tags for x86_64 and arm64.
+        Get CMake args from the settings and environment.
         """
+        # Adding CMake arguments set as environment variable
+        # (needed e.g. to build for ARM OSX on conda-forge)
+        env_cmake_args = filter(None, self.config.env.get("CMAKE_ARGS", "").split(" "))
 
-        archs = self.get_archs()
-        if sys.platform.startswith("darwin") and set(archs) == {"arm64", "x86_64"}:
-            return ["universal2"]
-        return archs
+        return [*self.settings.cmake.args, *env_cmake_args]
 
     def configure(
         self,
@@ -76,7 +85,6 @@ def configure(
         limited_abi: bool | None = None,
     ) -> None:
         cmake_defines = dict(defines)
-        cmake_args: list[str] = []
 
         # Add site-packages to the prefix path for CMake
         site_packages = Path(sysconfig.get_path("purelib"))
@@ -151,18 +159,9 @@ def configure(
 
         self.config.init_cache(cache_config)
 
-        # Add the pre-defined or passed CMake args
-        cmake_args += self.settings.cmake.args
-
-        # Adding CMake arguments set as environment variable
-        # (needed e.g. to build for ARM OSX on conda-forge)
-        cmake_args += [
-            item for item in self.config.env.get("CMAKE_ARGS", "").split(" ") if item
-        ]
-
         if sys.platform.startswith("darwin"):
             # Cross-compile support for macOS - respect ARCHFLAGS if set
-            archs = self.get_archs()
+            archs = get_archs(self.config.env)
             if archs:
                 cmake_defines["CMAKE_OSX_ARCHITECTURES"] = ";".join(archs)
 
@@ -171,7 +170,7 @@ def configure(
 
         self.config.configure(
             defines=cmake_defines,
-            cmake_args=cmake_args,
+            cmake_args=self.get_cmake_args(),
         )
 
     def build(self, build_args: list[str]) -> None:

src/scikit_build_core/cmake.py

@@ -139,7 +139,7 @@ def init_cache(
         )
 
     def _compute_cmake_args(
-        self, settings: Mapping[str, str | os.PathLike[str] | bool]
+        self, defines: Mapping[str, str | os.PathLike[str] | bool]
     ) -> Generator[str, None, None]:
         yield f"-S{self.source_dir}"
         yield f"-B{self.build_dir}"
@@ -150,7 +150,7 @@ def _compute_cmake_args(
         if self.single_config and self.build_type:
             yield f"-DCMAKE_BUILD_TYPE={self.build_type}"
 
-        for key, value in settings.items():
+        for key, value in defines.items():
             if isinstance(value, bool):
                 value = "ON" if value else "OFF"
                 yield f"-D{key}:BOOL={value}"

src/scikit_build_core/setuptools/extension.py

@@ -12,7 +12,7 @@
 from setuptools.dist import Distribution
 
 from .._compat.typing import Literal
-from ..builder.builder import Builder
+from ..builder.builder import Builder, get_archs
 from ..builder.macos import normalize_macos_version
 from ..cmake import CMake, CMaker
 from ..settings.skbuild_read_settings import SettingsReader
@@ -77,7 +77,7 @@ def build_extension(self, ext: setuptools.Extension) -> None:
 
         # Setuptools requires this be specified if there's a mismatch.
         if sys.platform.startswith("darwin"):
-            arm_only = builder.get_archs() == ["arm64"]
+            arm_only = get_archs(builder.config.env) == ["arm64"]
             orig_macos_str = sysconfig.get_platform().rsplit("-", 1)[0].split("-", 1)[1]
             orig_macos = normalize_macos_version(orig_macos_str, arm_only)
             config.env.setdefault("MACOSX_DEPLOYMENT_TARGET", str(orig_macos))

tests/test_builder.py

@@ -9,7 +9,7 @@
 
 import pytest
 
-from scikit_build_core.builder.builder import Builder
+from scikit_build_core.builder.builder import Builder, archs_to_tags, get_archs
 from scikit_build_core.builder.macos import get_macosx_deployment_target
 from scikit_build_core.builder.sysconfig import (
     get_python_include_dir,
@@ -87,12 +87,7 @@ def test_get_python_library_xcompile(tmp_path):
 def test_builder_macos_arch(monkeypatch, archs):
     archflags = " ".join(f"-arch {arch}" for arch in archs)
     monkeypatch.setattr(sys, "platform", "darwin")
-    monkeypatch.setenv("ARCHFLAGS", archflags)
-    tmpcfg = SimpleNamespace(env=os.environ.copy())
-    tmpbuilder = typing.cast(
-        Builder, SimpleNamespace(config=tmpcfg, settings=ScikitBuildSettings())
-    )
-    assert Builder.get_archs(tmpbuilder) == archs
+    assert get_archs({"ARCHFLAGS": archflags}) == archs
 
 
 def test_builder_macos_arch_extra(monkeypatch):
@@ -105,7 +100,7 @@ def test_builder_macos_arch_extra(monkeypatch):
         settings=ScikitBuildSettings(wheel=WheelSettings()),
         config=tmpcfg,
     )
-    assert tmpbuilder.get_arch_tags() == ["universal2"]
+    assert archs_to_tags(get_archs(tmpbuilder.config.env)) == ["universal2"]
 
 
 @pytest.mark.parametrize(