Use in run tests

Author: JukkaL

mypyc/test/librt_cache.py

@@ -186,7 +186,8 @@ def get_librt_path(experimental: bool = True) -> str:
         with open(setup_py, "w") as f:
             f.write(_generate_setup_py(build_dir, experimental))
 
-        # Build
+        # Build (parallel builds don't work well because multiple extensions
+        # share the same runtime C files, causing race conditions)
         result = subprocess.run(
             [sys.executable, setup_py, "build_ext", "--inplace"],
             cwd=build_dir,

mypyc/test/test_run.py

@@ -27,6 +27,7 @@
 from mypyc.options import CompilerOptions
 from mypyc.test.config import test_data_prefix
 from mypyc.test.test_serialization import check_serialization_roundtrip
+from mypyc.test.librt_cache import get_librt_path
 from mypyc.test.testutil import (
     ICODE_GEN_BUILTINS,
     TESTUTIL_PATH,
@@ -289,6 +290,7 @@ def run_case_step(self, testcase: DataDrivenTestCase, incremental_step: int) ->
 
         setup_file = os.path.abspath(os.path.join(WORKDIR, "setup.py"))
         # We pass the C file information to the build script via setup.py unfortunately
+        # Note: install_librt is always False since we use cached librt from librt_cache
         with open(setup_file, "w", encoding="utf-8") as f:
             f.write(
                 setup_format.format(
@@ -297,16 +299,15 @@ def run_case_step(self, testcase: DataDrivenTestCase, incremental_step: int) ->
                     (cfiles, deps),
                     self.multi_file,
                     opt_level,
-                    librt,
+                    False,  # install_librt - use cached version instead
                     experimental_features,
                 )
             )
 
         if librt:
-            # This hack forces Python to prefer the local "installation".
-            os.makedirs("librt", exist_ok=True)
-            with open(os.path.join("librt", "__init__.py"), "a"):
-                pass
+            # Use cached pre-built librt instead of rebuilding for each test
+            cached_librt = get_librt_path(experimental_features)
+            shutil.copytree(os.path.join(cached_librt, "librt"), "librt")
 
         if not run_setup(setup_file, ["build_ext", "--inplace"]):
             if testcase.config.getoption("--mypyc-showc"):