gh-91321: Fix compatibility with C++ older than C++11 (#93784)

Fix the compatibility of the Python C API with C++ older than C++11.

_Py_NULL is only defined as nullptr on C++11 and newer.

1 files changed, 14 insertions, 5 deletions

diff --git a/Lib/test/setup_testcppext.py b/Lib/test/setup_testcppext.py
index 780cb7b..a288dbd 100644
--- a/Lib/test/setup_testcppext.py
+++ b/Lib/test/setup_testcppext.py
@@ -13,8 +13,6 @@ SOURCE = support.findfile('_testcppext.cpp')
 if not MS_WINDOWS:
     # C++ compiler flags for GCC and clang
     CPPFLAGS = [
-        # Python currently targets C++11
-        '-std=c++11',
         # 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
@@ -30,12 +28,23 @@ else:
 
 
 def main():
+    cppflags = list(CPPFLAGS)
+    if '-std=c++03' in sys.argv:
+        sys.argv.remove('-std=c++03')
+        std = 'c++03'
+        name = '_testcpp03ext'
+    else:
+        # Python currently targets C++11
+        std = 'c++11'
+        name = '_testcpp11ext'
+
+    cppflags = [*CPPFLAGS, f'-std={std}']
     cpp_ext = Extension(
-        '_testcppext',
+        name,
         sources=[SOURCE],
         language='c++',
-        extra_compile_args=CPPFLAGS)
-    setup(name="_testcppext", ext_modules=[cpp_ext])
+        extra_compile_args=cppflags)
+    setup(name=name, ext_modules=[cpp_ext])
 
 
 if __name__ == "__main__":