gh-108303: Add Lib/test/test_cppext/ sub-directory (#108325)

* Move test_cppext to its own directory
* Rename setup_testcppext.py to setup.py
* Rename _testcppext.cpp to extension.cpp
* The source (extension.cpp) is now also copied by the test.

1 files changed, 42 insertions, 0 deletions

diff --git a/Lib/test/test_cppext/setup.py b/Lib/test/test_cppext/setup.py
new file mode 100644
index 00000000000..6867094a420
--- /dev/null
+++ b/Lib/test/test_cppext/setup.py
@@ -0,0 +1,42 @@
+# gh-91321: Build a basic C++ test extension to check that the Python C API is
+# compatible with C++ and does not emit C++ compiler warnings.
+import os
+import sys
+
+from setuptools import setup, Extension
+
+
+MS_WINDOWS = (sys.platform == 'win32')
+
+
+SOURCE = 'extension.cpp'
+if not MS_WINDOWS:
+    # C++ compiler flags for GCC and clang
+    CPPFLAGS = [
+        # gh-91321: The purpose of _testcppext extension is to check that building
+        # a C++ extension using the Python C API does not emit C++ compiler
+        # warnings
+        '-Werror',
+    ]
+else:
+    # Don't pass any compiler flag to MSVC
+    CPPFLAGS = []
+
+
+def main():
+    cppflags = list(CPPFLAGS)
+    std = os.environ["CPYTHON_TEST_CPP_STD"]
+    name = os.environ["CPYTHON_TEST_EXT_NAME"]
+
+    cppflags = [*CPPFLAGS, f'-std={std}']
+
+    cpp_ext = Extension(
+        name,
+        sources=[SOURCE],
+        language='c++',
+        extra_compile_args=cppflags)
+    setup(name='internal' + name, version='0.0', ext_modules=[cpp_ext])
+
+
+if __name__ == "__main__":
+    main()