From: Steve Dower <steve.dower@python.org>
Date: Fri, 15 May 2026 13:43:41 +0000 (+0100)
Subject: gh-149786: Fixes venvlauncher builds on Windows free-threaded (GH-149847)
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1c5fe21eb2a65190c04bb3f4c0931d76f5ccf415;p=thirdparty%2FPython%2Fcpython.git

gh-149786: Fixes venvlauncher builds on Windows free-threaded (GH-149847)
---

diff --git a/Lib/test/test_venv.py b/Lib/test/test_venv.py
index a42787f261bf..9d2960664abf 100644
--- a/Lib/test/test_venv.py
+++ b/Lib/test/test_venv.py
@@ -301,9 +301,9 @@ class BasicTest(BaseTest):
                 self.assertEqual(out.strip(), expected, err)
         for attr, expected in (
             ('executable', self.envpy()),
-            # Usually compare to sys.executable, but if we're running in our own
-            # venv then we really need to compare to our base executable
-            ('_base_executable', sys._base_executable),
+            # Usually compare to sys.prefix, but if we're running in our own
+            # venv then we really need to compare to our base prefix
+            ('base_prefix', sys.base_prefix),
         ):
             with self.subTest(attr):
                 cmd[2] = f'import sys; print(sys.{attr})'
@@ -916,10 +916,10 @@ class BasicTest(BaseTest):
             exename = exename.replace("python", "pythonw")
         envpyw = os.path.join(self.env_dir, self.bindir, exename)
         try:
-            subprocess.check_call([envpyw, "-c", "import sys; "
-                "assert sys._base_executable.endswith('%s')" % exename])
+            subprocess.check_call([envpyw, "-c", "import fnmatch, sys; "
+                "assert fnmatch.fnmatch(sys._base_executable, '**/pythonw*.exe')"])
         except subprocess.CalledProcessError:
-            self.fail("venvwlauncher.exe did not run %s" % exename)
+            self.fail("venvwlauncher.exe did not run pythonw.exe")
 
 
 @requireVenvCreate
diff --git a/Misc/NEWS.d/next/Windows/2026-05-14-22-09-46.gh-issue-149786.UI-HZM.rst b/Misc/NEWS.d/next/Windows/2026-05-14-22-09-46.gh-issue-149786.UI-HZM.rst
new file mode 100644
index 000000000000..64ca91a01f41
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2026-05-14-22-09-46.gh-issue-149786.UI-HZM.rst
@@ -0,0 +1 @@
+Fixes virtual environment launchers on Windows free-threaded builds.
diff --git a/PC/layout/support/options.py b/PC/layout/support/options.py
index 3a6e00f720f0..f67d8ba04d90 100644
--- a/PC/layout/support/options.py
+++ b/PC/layout/support/options.py
@@ -112,6 +112,7 @@ PRESETS = {
             "venv",
             "dev",
             "html-doc",
+            "alias",
             "install-json",
             "builddetails-json",
         ],
@@ -128,6 +129,7 @@ PRESETS = {
             "html-doc",
             "symbols",
             "tests",
+            "alias",
             "install-test-json",
             "builddetails-json",
         ],
diff --git a/PC/layout/support/pymanager.py b/PC/layout/support/pymanager.py
index 831d49ea3f9b..f6316e0295c7 100644
--- a/PC/layout/support/pymanager.py
+++ b/PC/layout/support/pymanager.py
@@ -66,8 +66,9 @@ def calculate_install_json(ns, *, for_embed=False, for_test=False):
     if ns.include_freethreaded:
         # Free-threaded distro comes with a tag suffix
         TAG_SUFFIX = "t"
-        TARGET = f"python{VER_MAJOR}.{VER_MINOR}t.exe"
-        TARGETW = f"pythonw{VER_MAJOR}.{VER_MINOR}t.exe"
+        if not ns.include_alias:
+            TARGET = f"python{VER_MAJOR}.{VER_MINOR}t.exe"
+            TARGETW = f"pythonw{VER_MAJOR}.{VER_MINOR}t.exe"
         DISPLAY_TAGS.append("free-threaded")
         FILE_SUFFIX = f"t-{ns.arch}"
 
diff --git a/PCbuild/python.vcxproj b/PCbuild/python.vcxproj
index 70dabaa3c8bc..417ede34c54a 100644
--- a/PCbuild/python.vcxproj
+++ b/PCbuild/python.vcxproj
@@ -135,6 +135,14 @@
 set PYTHONPATH=$(PySourcePath)Lib
 "$(OutDir)$(PyExeName)$(PyDebugExt).exe" "$(PySourcePath)PC\validate_ucrtbase.py" $(UcrtName)' ContinueOnError="true" />
   </Target>
+  <Target Name="CopyFreethreadedBinary" AfterTargets="AfterBuild"
+          Condition="$(DisableGil) == 'true' and $(Configuration) != 'PGInstrument'">
+    <Message Text="Duplicating $(TargetPath) to $(PyExeName)$(MajorVersionNumber).$(MinorVersionNumber)t$(PyDebugExt).exe for free-threaded compatibility" />
+    <Copy SourceFiles="$(TargetPath)"
+          DestinationFiles="$(OutDir)\$(PyExeName)$(MajorVersionNumber).$(MinorVersionNumber)t$(PyDebugExt).exe"
+          SkipUnchangedFiles="true"
+          UseHardLinksIfPossible="true" />
+  </Target>
   <Target Name="GeneratePythonBat" AfterTargets="AfterBuild">
     <PropertyGroup>
       <_Content>@rem This script invokes the most recently built Python with all arguments
diff --git a/PCbuild/pythonw.vcxproj b/PCbuild/pythonw.vcxproj
index c6a5b8ce90a0..244cdf622ad9 100644
--- a/PCbuild/pythonw.vcxproj
+++ b/PCbuild/pythonw.vcxproj
@@ -115,4 +115,12 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
+  <Target Name="CopyFreethreadedBinary" AfterTargets="AfterBuild"
+          Condition="$(DisableGil) == 'true' and $(Configuration) != 'PGInstrument'">
+    <Message Text="Duplicating $(TargetPath) to $(PyWExeName)$(MajorVersionNumber).$(MinorVersionNumber)t$(PyDebugExt).exe for free-threaded compatibility" />
+    <Copy SourceFiles="$(TargetPath)"
+          DestinationFiles="$(OutDir)\$(PyWExeName)$(MajorVersionNumber).$(MinorVersionNumber)t$(PyDebugExt).exe"
+          SkipUnchangedFiles="true"
+          UseHardLinksIfPossible="true" />
+  </Target>
 </Project>
\ No newline at end of file
diff --git a/PCbuild/venvlauncher.vcxproj b/PCbuild/venvlauncher.vcxproj
index abaf3a979af2..a2e8ffa82b10 100644
--- a/PCbuild/venvlauncher.vcxproj
+++ b/PCbuild/venvlauncher.vcxproj
@@ -89,10 +89,13 @@
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
     <Import Project="pyproject.props" />
   </ImportGroup>
-  <PropertyGroup Label="UserMacros" />
+  <PropertyGroup Label="UserMacros">
+    <ExeName>$(PyExeName)$(PyDebugExt).exe</ExeName>
+    <ExeName Condition="$(DisableGil) == 'true'">$(PyExeName)$(MajorVersionNumber).$(MinorVersionNumber)t$(PyDebugExt).exe</ExeName>
+  </PropertyGroup>
   <ItemDefinitionGroup>
     <ClCompile>
-      <PreprocessorDefinitions>EXENAME=L"$(PyExeName)$(PyDebugExt).exe";_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>EXENAME=L"$(ExeName)";_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
     </ClCompile>
     <ResourceCompile>
diff --git a/PCbuild/venvwlauncher.vcxproj b/PCbuild/venvwlauncher.vcxproj
index c58280deb8ab..f2aaf83fe2b3 100644
--- a/PCbuild/venvwlauncher.vcxproj
+++ b/PCbuild/venvwlauncher.vcxproj
@@ -89,10 +89,13 @@
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
     <Import Project="pyproject.props" />
   </ImportGroup>
-  <PropertyGroup Label="UserMacros" />
+  <PropertyGroup Label="UserMacros">
+    <ExeName>$(PyWExeName)$(PyDebugExt).exe</ExeName>
+    <ExeName Condition="$(DisableGil) == 'true'">$(PyWExeName)$(MajorVersionNumber).$(MinorVersionNumber)t$(PyDebugExt).exe</ExeName>
+  </PropertyGroup>
   <ItemDefinitionGroup>
     <ClCompile>
-      <PreprocessorDefinitions>EXENAME=L"$(PyWExeName)$(PyDebugExt).exe";_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>EXENAME=L"$(ExeName)";_WINDOWS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
     </ClCompile>
     <ResourceCompile>