A recent commit added a typedef for PyTypeObject in Include/object.h

https://github.com/python/cpython/commit/0e4e735d06967145b49fd00693627f3624991dbc

This duplicates the typedef in Include/cpython/object.h. Building with clang now issues a warning:

./Include/cpython/object.h:274:3: warning: redefinition of typedef 'PyTypeObject' is a C11 feature [-Wtypedef-redefinition]

This is due to the combination of `-Wall` and `-std=c99`. GCC will only warn if the `-pedantic` option is specified.

Sorry, I only tested GCC and I forgot that clang is more pedantic on duplicated typedef. I looked better with PyTypeObject, but the fix is easy: just revert my change: PR 18384.

Alternatively I think you can just remove the typedef from Include/cpython/object.h since Include/object.h is always included first. i.e.:

typedef struct _typeobject {
  ...
} PyTypeObject;

to simply

struct _typeobject {
  ...
};

> Alternatively I think you can just remove the typedef from Include/cpython/object.h since Include/object.h is always included first. i.e.:

Oh, nice! I proposed PR 18385. Would you mind to confirm that it fix the issue for you? At least, I tested manually and the clang warning goes away with this change.

Yes, that fixes the warnings for me. Thanks!

New changeset f95cd199b4bc16775c8c48641bd85416b17742e7 by Victor Stinner in branch 'master':
bpo-39571: Fix clang warning on PyTypeObject typedef (GH-18385)
https://github.com/python/cpython/commit/f95cd199b4bc16775c8c48641bd85416b17742e7

Thanks Sam Gross for the hint, it's now fixed.