The header file pyconfig.h mishandles the _POSIX_C_SOURCE and _XOPEN_SOURCE preprocessor macros.

For older versions of Python, the pyconfig.h header specifies:

#define _POSIX_C_SOURCE 200112L

and:

#define _XOPEN_SOURCE 600

For newer versions of Python, the pyconfig.h header specifies:

#define _POSIX_C_SOURCE 200809L

and:

#define _XOPEN_SOURCE 700

The Open Group has documentation about these symbols:

http://pubs.opengroup.org/onlinepubs/007904975/functions/xsh_chap02_02.html

In particular, the documentation states:

A POSIX-conforming application should ensure that the feature test macro _POSIX_C_SOURCE is defined before inclusion of any header.

So, having a header file attempting to set _POSIX_C_SOURCE violates this intention.

Yes, I am well aware that the Python documentation says to include Python.h before any standard headers are included.  However, this is still problematic.

In particular, it causes trouble for source code that wishes to include the Python headers and wishes to use declarations that are made visible by setting later values for _POSIX_C_SOURCE and _XOPEN_SOURCE.

I would suggest the pyconfig.h be updated to have something like this:

#if !defined(_POSIX_C_SOURCE) || _POSIX_C_SOURCE < 200112L
#ifdef _POSIX_C_SOURCE
#warning Python expects -D_POSIX_C_SOURCE=200112L or later
#undef _POSIX_C_SOURCE
#endif
#define _POSIX_C_SOURCE 200112L
#endif

and this:

#if !defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600
#ifdef _XOPEN_SOURCE
#warning Python expects -D_XOPEN_SOURCE=600 or later
#undef _XOPEN_SOURCE
#endif
#define _XOPEN_SOURCE 600
#endif