feat: add sysconfig helpers (#21)

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

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

Author: henryiii

src/scikit_build_core/builder/sysconfig.py

@@ -0,0 +1,53 @@
+from __future__ import annotations
+
+import os
+import sysconfig
+from pathlib import Path
+
+from .._logging import logger
+
+__all__ = ["get_python_include_dir", "get_python_library"]
+
+
+def __dir__() -> list[str]:
+    return __all__
+
+
+def get_python_library() -> Path | None:
+    libdirstr = sysconfig.get_config_var("LIBDIR")
+    ldlibrarystr = sysconfig.get_config_var("LDLIBRARY")
+    libdir = libdirstr and Path(libdirstr)
+    ldlibrary = ldlibrarystr and Path(ldlibrarystr)
+    multiarch = sysconfig.get_config_var("MULTIARCH")
+    masd = sysconfig.get_config_var("multiarchsubdir")
+
+    if libdir and ldlibrary and libdir.is_dir():
+        if multiarch:
+            if masd:
+                if masd.startswith(os.sep):
+                    masd = masd[len(os.sep) :]
+                libdir_masd = libdir / masd
+                if libdir_masd.is_dir():
+                    libdir = libdir_masd
+        libpath = Path(libdir) / ldlibrary
+        if libpath.is_file():
+            return libpath
+
+    framework_prefix = sysconfig.get_config_var("PYTHONFRAMEWORKPREFIX")
+    if framework_prefix and Path(framework_prefix).is_dir() and ldlibrary:
+        libpath = Path(framework_prefix) / ldlibrary
+        if libpath.is_file():
+            return libpath
+
+    logger.error(
+        "Can't find a Python library, got libdir={}, ldlibrary={}, multiarch={}, masd={}",
+        libdir,
+        ldlibrary,
+        multiarch,
+        masd,
+    )
+    return None
+
+
+def get_python_include_dir() -> Path:
+    return Path(sysconfig.get_path("include"))

tests/test_builder.py

@@ -1,8 +1,15 @@
 import platform
+import pprint
+import sys
+import sysconfig
 
 import pytest
 
 from scikit_build_core.builder.macos import get_macosx_deployment_target
+from scikit_build_core.builder.sysconfig import (
+    get_python_include_dir,
+    get_python_library,
+)
 
 
 @pytest.mark.parametrize(
@@ -26,3 +33,18 @@ def test_macos_version(monkeypatch, pycom, envvar, answer):
         monkeypatch.setenv("MACOSX_DEPLOYMENT_TARGET", envvar)
 
     assert get_macosx_deployment_target() == answer
+
+
+def test_get_python_include_dir():
+    assert get_python_include_dir().is_dir()
+
+
+def test_get_python_library():
+    pprint.pprint(sysconfig.get_config_vars())
+
+    lib = get_python_library()
+    if sys.platform.startswith("win"):
+        assert lib is None
+    else:
+        assert lib
+        assert lib.is_file()