devenv: do not use os.execv on Windows

On Windows, os.execv spawn the process in background and returns 0.
Therefore, it prevents devenv to return proper exit code from the
called process. (see https://github.com/python/cpython/issues/63323
for reference.)

The solution is to call subprocess.run instead, on Windows, at the
price of keeping the meson python process alive while the devenv
subprocess runs.

2 files changed, 13 insertions, 2 deletions

diff --git a/mesonbuild/mdevenv.py b/mesonbuild/mdevenv.py
index 4962d96c6..e9974fe86 100644
--- a/mesonbuild/mdevenv.py
+++ b/mesonbuild/mdevenv.py
@@ -4,6 +4,7 @@ import os, subprocess
 import argparse
 import tempfile
 import shutil
+import sys
 import itertools
 import typing as T
 
@@ -226,8 +227,14 @@ def run(options: argparse.Namespace) -> int:
         args[0] = abs_path or args[0]
 
     try:
-        os.chdir(workdir)
-        os.execvpe(args[0], args, env=devenv)
+        if is_windows():
+            # execvpe doesn't return exit code on Windows
+            # see https://github.com/python/cpython/issues/63323
+            result = subprocess.run(args, env=devenv, cwd=workdir)
+            sys.exit(result.returncode)
+        else:
+            os.chdir(workdir)
+            os.execvpe(args[0], args, env=devenv)
     except FileNotFoundError:
         raise MesonException(f'Command not found: {args[0]}')
     except OSError as e:
diff --git a/unittests/allplatformstests.py b/unittests/allplatformstests.py
index 0618b20ee..b983f341c 100644
--- a/unittests/allplatformstests.py
+++ b/unittests/allplatformstests.py
@@ -4453,6 +4453,10 @@ class AllPlatformTests(BasePlatformTests):
         self.assertIn(f'TEST_C="{expected}"', o)
         self.assertIn('export TEST_C', o)
 
+        cmd = self.meson_command + ['devenv', '-C', self.builddir] + python_command + ['-c', 'import sys; sys.exit(42)']
+        result = subprocess.run(cmd, encoding='utf-8')
+        self.assertEqual(result.returncode, 42)
+
     def test_clang_format_check(self):
         if self.backend is not Backend.ninja:
             raise SkipTest(f'Skipping clang-format tests with {self.backend.name} backend')