[New-bugs-announce] [issue17120] Mishandled _POSIX_C_SOURCE and _XOPEN_SOURCE in pyconfig.h

RAW report at bugs.python.org
Mon Feb 4 06:39:07 CET 2013

New submission from RAW:

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


#define _XOPEN_SOURCE 600

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

#define _POSIX_C_SOURCE 200809L


#define _XOPEN_SOURCE 700

The Open Group has documentation about these symbols:


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
#warning Python expects -D_POSIX_C_SOURCE=200112L or later
#define _POSIX_C_SOURCE 200112L

and this:

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

components: Library (Lib)
messages: 181309
nosy: RAW
priority: normal
severity: normal
status: open
title: Mishandled _POSIX_C_SOURCE and _XOPEN_SOURCE in pyconfig.h
type: compile error
versions: Python 2.6, Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4, Python 3.5

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