gh-138489: Install build-details.json on Windows

Lib/test/test_build_details.py

@@ -90,24 +90,27 @@ def test_implementation(self):
 )
 
 
-@unittest.skipIf(os.name != 'posix', 'Feature only implemented on POSIX right now')
 @unittest.skipIf(is_wasm32, 'Feature not available on WebAssembly builds')
 class CPythonBuildDetailsTests(unittest.TestCase, FormatTestsBase):
     """Test CPython's install details file implementation."""
 
     @property
     def location(self):
         if sysconfig.is_python_build():
-            projectdir = sysconfig.get_config_var('projectbase')
-            with open(os.path.join(projectdir, 'pybuilddir.txt')) as f:
-                dirname = os.path.join(projectdir, f.read())
+            if sys.platform == 'win32':
+                dirname = sysconfig.get_config_var('BINDIR')
+            else:
+                projectdir = sysconfig.get_config_var('projectbase')
+                pybuilddir = os.path.join(projectdir, 'pybuilddir.txt')
+                with open(pybuilddir, encoding='utf-8') as f:
+                    dirname = os.path.join(projectdir, f.read())
         else:
             dirname = sysconfig.get_path('stdlib')
         return os.path.join(dirname, 'build-details.json')
 
     @property
     def contents(self):
-        with open(self.location, 'r') as f:
+        with open(self.location, 'r', encoding='utf-8') as f:
             return f.read()
 
     @needs_installed_python

Misc/NEWS.d/next/Core_and_Builtins/2025-09-04-00-32-28.gh-issue-138489.Adc9Lx.rst

@@ -0,0 +1,3 @@
+The :pep:`739` :file:`build-details.json` file is now generated and
+installed on Windows.
+Patch by Adam Turner.

PCbuild/python.vcxproj

@@ -126,6 +126,12 @@
     <Message Text="Generating $(OutDir)pybuilddir.txt" />
     <WriteLinesToFile File="$(OutDir)pybuilddir.txt" Lines="%0D%0A" Overwrite="true" />
   </Target>
+  <Target Name="GenerateBuildDetailsJSON" AfterTargets="Link">
+    <Message Text="Generating $(OutDir)build-details.json" />
+    <Exec Command='setlocal
+set PYTHONPATH=$(PySourcePath)Lib
+"$(OutDir)$(PyExeName)$(PyDebugExt).exe" "$(PySourcePath)Tools\build\generate-build-details.py" "$(OutDir)build-details.json"' ContinueOnError="true" />
+  </Target>
   <Target Name="ValidateUcrtbase" AfterTargets="AfterBuild" Condition="$(Configuration) != 'PGInstrument' and $(Platform) != 'ARM' and $(Platform) != 'ARM64'">
     <PropertyGroup>
       <UcrtName>ucrtbase</UcrtName>

PCbuild/pythoncore.vcxproj

@@ -735,4 +735,7 @@
   <Target Name="_DeletePyBuildDirTxt" BeforeTargets="PrepareForBuild">
     <Delete Files="$(OutDir)pybuilddir.txt" />
   </Target>
+  <Target Name="_DeleteBuildDetailsJson" BeforeTargets="PrepareForBuild">
+    <Delete Files="$(OutDir)build-details.json" />
+  </Target>
 </Project>

Tools/build/generate-build-details.py

@@ -55,13 +55,16 @@ def generate_data(schema_version: str) -> collections.defaultdict[str, Any]:
     data['language']['version'] = sysconfig.get_python_version()
     data['language']['version_info'] = version_info_to_dict(sys.version_info)
 
-    data['implementation'] = vars(sys.implementation)
+    data['implementation'] = vars(sys.implementation).copy()
     data['implementation']['version'] = version_info_to_dict(sys.implementation.version)
     # Fix cross-compilation
     if '_multiarch' in data['implementation']:
         data['implementation']['_multiarch'] = sysconfig.get_config_var('MULTIARCH')
 
-    data['abi']['flags'] = list(sys.abiflags)
+    if os.name != 'nt':
+        data['abi']['flags'] = list(sys.abiflags)
+    else:
+        data['abi']['flags'] = []
 
     data['suffixes']['source'] = importlib.machinery.SOURCE_SUFFIXES
     data['suffixes']['bytecode'] = importlib.machinery.BYTECODE_SUFFIXES
@@ -104,7 +107,7 @@ def generate_data(schema_version: str) -> collections.defaultdict[str, Any]:
         data['abi']['extension_suffix'] = sysconfig.get_config_var('EXT_SUFFIX')
 
         # EXTENSION_SUFFIXES has been constant for a long time, and currently we
-        # don't have a better information source to find the  stable ABI suffix.
+        # don't have a better information source to find the stable ABI suffix.
         for suffix in importlib.machinery.EXTENSION_SUFFIXES:
             if suffix.startswith('.abi'):
                 data['abi']['stable_abi_suffix'] = suffix
@@ -186,8 +189,9 @@ def main() -> None:
         make_paths_relative(data, args.config_file_path)
 
     json_output = json.dumps(data, indent=2)
-    with open(args.location, 'w') as f:
-        print(json_output, file=f)
+    with open(args.location, 'w', encoding='utf-8') as f:
+        f.write(json_output)
+        f.write('\n')
 
 
 if __name__ == '__main__':