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[Bug c/30475] assert(int+100 > int) optimized away
- From: "js at linuxtv dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 8 Mar 2007 16:22:46 -0000
- Subject: [Bug c/30475] assert(int+100 > int) optimized away
- References: <bug-30475-3511@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #55 from js at linuxtv dot org 2007-03-08 16:22 -------
Point taken. I was misled by the mentioning of C99 6.3.1.3
in comment #18, that this would apply to integer conversion.
Funnily enough, C99 3.4.3 even says "An example of undefined
behavior is the behavior on integer overflow."
I should've read that one more thoroughly.
C99 Annex H (Informative) says:
"C?s unsigned integer types are ??modulo?? in the LIA−1 sense
in that overflows or out-of-bounds results silently wrap. An
implementation that defines signed integer types as also being
modulo need not detect integer overflow, in which case, only
integer divide-by-zero need be detected."
Which suggests that implmentations define signed integer
overflow semantics, but maybe it's just bad wording, and
anyway it's not part of the standard proper.
Sorry for the noise and thanks for the C lesson.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30475