[New-bugs-announce] [issue16881] Py_ARRAY_LENGTH macro incorrect with GCC < 3.1

Jeffrey Armstrong report at bugs.python.org
Sun Jan 6 16:32:47 CET 2013

New submission from Jeffrey Armstrong:

The Py_ARRAY_LENGTH macro (Include/pymacro.h:36) checks to see if using GCC by simply looking for __GCC__ being defined.  If so, it uses the GCC extension function "__builtin_types_compatible_p."  However, this function was not introduced until GCC 3.1.  This simple check for a GCC compiler causes the Python build to fail on GCC < 3.1 (2.95 for example).

The check should actually be:

#if (defined(__GNUC__) && !defined(__STRICT_ANSI__) && \
    ((__GNUC__ == 3) && (__GNU_MINOR__) >= 1) || (__GNUC__ >= 4)))

Similar checks are made in other locations in the core library, just not here.  

This bug was discovered while attempting a build on m68k-atari-mint, which relies on GCC 2.95.3.  Other systems may also be using this compiler still.

components: Build
messages: 179187
nosy: Jeffrey.Armstrong
priority: normal
severity: normal
status: open
title: Py_ARRAY_LENGTH macro incorrect with GCC < 3.1
type: compile error
versions: Python 3.3

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