Bugs item #1521947, was opened at 2006-07-13 10:39 Message generated for change (Comment added) made by nnorwitz You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1521947&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Python Interpreter Core Group: None Status: Open Resolution: None Priority: 5 Submitted By: Marien Zwart (marienz) Assigned to: Nobody/Anonymous (nobody) Summary: possible bug in mystrtol.c with recent gcc Initial Comment: python 2.5b2 compiled with gentoo's gcc 4.1.1 and -O2 fails test_unary_minus in test_compile.py. Some investigating showed that the -ftree-vrp pass of that gcc (implied by -O2) optimizes out the "result == -result" test on line 215 of PyOS_strtol, meaning PyOS_strtol of the most negative long will incorrectly overflow. Python deals with this in this case by constructing a python long object instead of a python int object, so at least in this case the problem is not serious. I have no idea if there is a case where this is a "real" problem. At first I reported this as a gentoo compiler bug, but got the reply that: """ I'm pretty sure it's broken. -LONG_MIN overflows when LONG_MIN < -LONG_MAX, and in standard C as well as "GNU C", behaviour after overflow on signed integer operations is undefined. """ (see https://bugs.gentoo.org/show_bug.cgi?id=140133) So now I'm reporting this here. There seems to be a LONG_MIN constant in limits.h here that could checked against instead, but I have absolutely no idea how standard that is. Or this could be a compiler bug after all, in which case I would appreciate information I Can use to back that up :) ---------------------------------------------------------------------- >Comment By: Neal Norwitz (nnorwitz) Date: 2006-07-16 18:13 Message: Logged In: YES user_id=33168 Is this a duplicate of 1521726? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1521947&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
