Bug report

Bug description:

When compiling a program that links against the Python libraries (and uses their headerfiles) with the-Werror=declaration-after-statement compiler flag enabled, the following error occurs:

/usr/include/python3.12/object.h:233:5: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]  233 |     PyVarObject *var_ob = _PyVarObject_CAST(ob);

This is fairly similar to previous issue#92781.

Although the C90 style may be archaic and perhaps not worth supporting at some point, maintaining support could be helpful for some downstream platforms (I encountered this in Debian bug#1057442).

#include"/usr/include/python3.11/Python.h"#include"/usr/include/python3.11/object.h"intmain() {}

#include"/usr/include/python3.12/Python.h"#include"/usr/include/python3.12/object.h"intmain() {}

$ gcc bugreport.c -Werror=declaration-after-statement

$ clang-17 bugreport.c -Werror=declaration-after-statement

CPython versions tested on:

3.12

Operating systems tested on:

Linux

Linked PRs

• gh-116869: Make C API compatible with ISO C90 #116950
• gh-116869: Add test_cext test: build a C extension #116954
• gh-116869: Fix redefinition of the _PyOptimizerObject type #116963
• gh-116869: Enable test_cext and test_cppext on Free Threading build #116973
• gh-116869: Build test_cext with -Werror=declaration-after-statement #116990
• gh-116869: Test the limited C API in test_cext #116995
• gh-116869: Fix test_cext on RHEL7 #117010
• [3.12] gh-116869: Make C API compatible with ISO C90 (GH-116950) #117011
• gh-116869: Fix test_cext for Free Threading #117043
• gh-116869: Enable -Werror in test_cext for Free Threading #117106