Fix missing Include/pyconfig.h in 3.13 Windows onedirs

Python <= 3.12 ships PC/pyconfig.h. Python 3.13+ replaced that file with
PC/pyconfig.h.in and MSBuild generates the real header into the build
output directory. The previous code skipped the copy entirely on 3.13
("if 3.13 not in ..."), so the produced tarballs had Python.h but no
pyconfig.h next to it -- every C extension build against the onedir
failed with "fatal error C1083: Cannot open include file: 'pyconfig.h'".

Replace the version-string check with a layout-driven copy that mirrors
CPython's PC/layout/main.py: when PC/pyconfig.h.in exists, take the
generated header from the PCbuild output directory; otherwise take the
checked-in PC/pyconfig.h. Raise if neither is found, so a future
regression cannot silently ship broken tarballs.

Add unit tests for both branches plus the missing-file error paths.

Author: dwoz

relenv/build/windows.py

@@ -230,7 +230,7 @@ def update_sqlite(dirs: Dirs, env: EnvMapping) -> None:
     sqliteversion = sqlite_info.get("sqliteversion", "3500400")
     url = sqlite_info["url"].format(version=sqliteversion)
     sha256 = sqlite_info["sha256"]
-    ref_loc = f"cpe:2.3:a:sqlite:sqlite:{version}:*:*:*:*:*:*:*"
+    ref_loc = f"cpe:2.3:a:sqlite:sqlite:{version}:*:*:*:*:*:*:*"  # noqa: E231
 
     target_dir = dirs.source / "externals" / f"sqlite-{version}"
     update_props(dirs.source, r"sqlite-\d+(\.\d+)*", f"sqlite-{version}")
@@ -268,7 +268,7 @@ def update_xz(dirs: Dirs, env: EnvMapping) -> None:
     version = xz_info["version"]
     url = xz_info["url"].format(version=version)
     sha256 = xz_info["sha256"]
-    ref_loc = f"cpe:2.3:a:tukaani:xz:{version}:*:*:*:*:*:*:*"
+    ref_loc = f"cpe:2.3:a:tukaani:xz:{version}:*:*:*:*:*:*:*"  # noqa: E231
 
     target_dir = dirs.source / "externals" / f"xz-{version}"
     update_props(dirs.source, r"xz-\d+(\.\d+)*", f"xz-{version}")
@@ -372,7 +372,7 @@ def update_openssl(dirs: Dirs, env: EnvMapping) -> None:
     version = openssl_info["version"]
     url = openssl_info["url"].format(version=version)
     sha256 = openssl_info["sha256"]
-    ref_loc = f"cpe:2.3:a:openssl:openssl:{version}:*:*:*:*:*:*:*"
+    ref_loc = f"cpe:2.3:a:openssl:openssl:{version}:*:*:*:*:*:*:*"  # noqa: E231
 
     is_binary = "cpython-bin-deps" in url
     target_dir = (
@@ -456,7 +456,9 @@ def update_openssl(dirs: Dirs, env: EnvMapping) -> None:
 
             env_path = os.environ.get("PATH", "")
             build_env = env.copy()
-            build_env["PATH"] = f"{perl_bin.parent};{nasm_exe[0].parent};{env_path}"
+            build_env[
+                "PATH"
+            ] = f"{perl_bin.parent};{nasm_exe[0].parent};{env_path}"  # noqa: E231,E702
 
             prefix = target_dir / "build"
             openssldir = prefix / "ssl"
@@ -607,7 +609,7 @@ def update_bzip2(dirs: Dirs, env: EnvMapping) -> None:
     version = bzip2_info["version"]
     url = bzip2_info["url"].format(version=version)
     sha256 = bzip2_info["sha256"]
-    ref_loc = f"cpe:2.3:a:bzip:bzip2:{version}:*:*:*:*:*:*:*"
+    ref_loc = f"cpe:2.3:a:bzip:bzip2:{version}:*:*:*:*:*:*:*"  # noqa: E231
 
     target_dir = dirs.source / "externals" / f"bzip2-{version}"
     update_props(dirs.source, r"bzip2-\d+(\.\d+)*", f"bzip2-{version}")
@@ -642,7 +644,7 @@ def update_libffi(dirs: Dirs, env: EnvMapping) -> None:
     version = libffi_info["version"]
     url = libffi_info["url"].format(version=version)
     sha256 = libffi_info["sha256"]
-    ref_loc = f"cpe:2.3:a:libffi_project:libffi:{version}:*:*:*:*:*:*:*"
+    ref_loc = f"cpe:2.3:a:libffi_project:libffi:{version}:*:*:*:*:*:*:*"  # noqa: E231
 
     target_dir = dirs.source / "externals" / f"libffi-{version}"
     update_props(dirs.source, r"libffi-\d+(\.\d+)*", f"libffi-{version}")
@@ -695,7 +697,7 @@ def update_zlib(dirs: Dirs, env: EnvMapping) -> None:
     version = zlib_info["version"]
     url = zlib_info["url"].format(version=version)
     sha256 = zlib_info["sha256"]
-    ref_loc = f"cpe:2.3:a:gnu:zlib:{version}:*:*:*:*:*:*:*"
+    ref_loc = f"cpe:2.3:a:gnu:zlib:{version}:*:*:*:*:*:*:*"  # noqa: E231
 
     target_dir = dirs.source / "externals" / f"zlib-{version}"
     update_props(dirs.source, r"zlib-\d+(\.\d+)*", f"zlib-{version}")
@@ -773,6 +775,37 @@ def update_perl(dirs: Dirs, env: EnvMapping) -> pathlib.Path:
     return target_dir
 
 
+def copy_pyconfig_h(
+    source: pathlib.Path, build_dir: pathlib.Path, dest_dir: pathlib.Path
+) -> pathlib.Path:
+    """
+    Copy ``pyconfig.h`` into the onedir's ``Include`` directory.
+
+    Python <= 3.12 ships a checked-in ``PC/pyconfig.h``. Python 3.13+ replaced
+    that with ``PC/pyconfig.h.in`` and MSBuild generates the real header into
+    the build output directory. This mirrors the logic in CPython's
+    ``PC/layout/main.py`` so the onedir's ``Include/`` always ends up with a
+    ``pyconfig.h`` next to ``Python.h`` -- without it C extensions cannot
+    locate the configuration macros and fail with
+    ``fatal error C1083: Cannot open include file: 'pyconfig.h'``.
+    """
+    pc_dir = source / "PC"
+    if (pc_dir / "pyconfig.h.in").is_file():
+        pyconfig_src = build_dir / "pyconfig.h"
+    else:
+        pyconfig_src = pc_dir / "pyconfig.h"
+
+    if not pyconfig_src.is_file():
+        raise RuntimeError(
+            f"Expected pyconfig.h at {pyconfig_src} but CPython build did "
+            "not produce it. Check that the MSBuild step ran successfully."
+        )
+
+    dest = dest_dir / "pyconfig.h"
+    shutil.copy(src=str(pyconfig_src), dst=str(dest))
+    return dest
+
+
 def build_python(env: EnvMapping, dirs: Dirs, logfp: IO[str]) -> None:
     """
     Run the commands to build Python.
@@ -843,7 +876,7 @@ def build_python(env: EnvMapping, dirs: Dirs, logfp: IO[str]) -> None:
         "python.exe",
         "pythonw.exe",
         "python3.dll",
-        f"python{ env['RELENV_PY_MAJOR_VERSION'].replace('.', '') }.dll",
+        f"python{env['RELENV_PY_MAJOR_VERSION'].replace('.', '')}.dll",
         "vcruntime140.dll",
         "venvlauncher.exe",
         "venvwlauncher.exe",
@@ -862,10 +895,7 @@ def build_python(env: EnvMapping, dirs: Dirs, logfp: IO[str]) -> None:
         dst=str(dirs.prefix / "Include"),
         dirs_exist_ok=True,
     )
-    if "3.13" not in env["RELENV_PY_MAJOR_VERSION"]:
-        shutil.copy(
-            src=str(dirs.source / "PC" / "pyconfig.h"), dst=str(dirs.prefix / "Include")
-        )
+    copy_pyconfig_h(dirs.source, build_dir, dirs.prefix / "Include")
 
     shutil.copytree(
         src=str(dirs.source / "Lib"), dst=str(dirs.prefix / "Lib"), dirs_exist_ok=True
@@ -877,7 +907,7 @@ def build_python(env: EnvMapping, dirs: Dirs, logfp: IO[str]) -> None:
         src=str(build_dir / "python3.lib"),
         dst=str(dirs.prefix / "libs" / "python3.lib"),
     )
-    pylib = f"python{ env['RELENV_PY_MAJOR_VERSION'].replace('.', '') }.lib"
+    pylib = f"python{env['RELENV_PY_MAJOR_VERSION'].replace('.', '')}.lib"
     shutil.copy(src=str(build_dir / pylib), dst=str(dirs.prefix / "libs" / pylib))
 
 

tests/test_build.py

@@ -454,3 +454,99 @@ def test_download_destination_setter() -> None:
     # Set to None
     d.destination = None
     assert d.destination == pathlib.Path()
+
+
+# copy_pyconfig_h tests
+#
+# Regression coverage for the bug where Windows onedirs for Python 3.13+ were
+# shipped without Include/pyconfig.h, breaking every C extension build.
+# Python <= 3.12 has a checked-in PC/pyconfig.h; Python 3.13+ replaced it
+# with PC/pyconfig.h.in and MSBuild generates the real header into the
+# PCbuild output directory. copy_pyconfig_h must pick the right one.
+
+
+def _make_layout(
+    tmp_path: pathlib.Path,
+    *,
+    has_in: bool,
+    pc_content: str = "",
+    build_content: str = "",
+) -> tuple[pathlib.Path, pathlib.Path, pathlib.Path]:
+    """Create source/, build_dir/, dest_dir/ trees mimicking a CPython tree."""
+    source = tmp_path / "cpython"
+    build_dir = tmp_path / "PCbuild" / "amd64"
+    dest_dir = tmp_path / "prefix" / "Include"
+    (source / "PC").mkdir(parents=True)
+    build_dir.mkdir(parents=True)
+    dest_dir.mkdir(parents=True)
+    if has_in:
+        (source / "PC" / "pyconfig.h.in").write_text("/* template */\n")
+        if build_content:
+            (build_dir / "pyconfig.h").write_text(build_content)
+    else:
+        if pc_content:
+            (source / "PC" / "pyconfig.h").write_text(pc_content)
+    return source, build_dir, dest_dir
+
+
+def test_copy_pyconfig_h_legacy(tmp_path: pathlib.Path) -> None:
+    """Python <= 3.12: copies PC/pyconfig.h (no pyconfig.h.in template)."""
+    from relenv.build.windows import copy_pyconfig_h
+
+    source, build_dir, dest_dir = _make_layout(
+        tmp_path, has_in=False, pc_content="/* checked in 3.12 */\n"
+    )
+    # Ensure the build_dir variant would NOT be picked up if it happened to
+    # exist as well -- the legacy path takes precedence when there's no .in.
+    (build_dir / "pyconfig.h").write_text("/* should be ignored */\n")
+
+    result = copy_pyconfig_h(source, build_dir, dest_dir)
+
+    assert result == dest_dir / "pyconfig.h"
+    assert result.is_file()
+    assert result.read_text() == "/* checked in 3.12 */\n"
+
+
+def test_copy_pyconfig_h_generated(tmp_path: pathlib.Path) -> None:
+    """Python 3.13+: copies the generated pyconfig.h from build_dir."""
+    from relenv.build.windows import copy_pyconfig_h
+
+    source, build_dir, dest_dir = _make_layout(
+        tmp_path, has_in=True, build_content="/* generated 3.13 */\n"
+    )
+    # A stale PC/pyconfig.h must NOT win when pyconfig.h.in is present.
+    (source / "PC" / "pyconfig.h").write_text("/* stale legacy */\n")
+
+    result = copy_pyconfig_h(source, build_dir, dest_dir)
+
+    assert result == dest_dir / "pyconfig.h"
+    assert result.is_file()
+    assert result.read_text() == "/* generated 3.13 */\n"
+
+
+def test_copy_pyconfig_h_missing_generated_raises(tmp_path: pathlib.Path) -> None:
+    """3.13+ layout but MSBuild didn't produce pyconfig.h -- must raise.
+
+    This is the failure mode that previously slipped through silently and
+    produced unusable tarballs.
+    """
+    from relenv.build.windows import copy_pyconfig_h
+
+    source, build_dir, dest_dir = _make_layout(tmp_path, has_in=True)
+    # No pyconfig.h written into build_dir.
+
+    with pytest.raises(RuntimeError, match="Expected pyconfig.h at"):
+        copy_pyconfig_h(source, build_dir, dest_dir)
+    assert not (dest_dir / "pyconfig.h").exists()
+
+
+def test_copy_pyconfig_h_missing_legacy_raises(tmp_path: pathlib.Path) -> None:
+    """Legacy layout but PC/pyconfig.h is absent -- must raise rather than silently no-op."""
+    from relenv.build.windows import copy_pyconfig_h
+
+    source, build_dir, dest_dir = _make_layout(tmp_path, has_in=False)
+    # No pyconfig.h written into PC/ either.
+
+    with pytest.raises(RuntimeError, match="Expected pyconfig.h at"):
+        copy_pyconfig_h(source, build_dir, dest_dir)
+    assert not (dest_dir / "pyconfig.h").exists()