Bug 82681
| Summary: | gcc warning on possible code problem is issuedinconstently | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | Michael Marxmeier <mike> |
| Component: | gcc3 | Assignee: | Jakub Jelinek <jakub> |
| Status: | CLOSED NOTABUG | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 8.0 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i386 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2003-01-24 20:54:11 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
Your code triggers undefined behaviour, and as such gcc can do anything it wants with it. As i wrote above, it might be undefined behavior and i'm not arguing that (it's just likely to break lots of existing code). However (IMHO) gcc should issue the warning consistently if -Wall is present. I've seen a number of cases where the warning was not issued, with -O used. I'm not pushing this but please consider to reopen the bug for the issue #2 (warning) - i've updated the subject accordingly. |
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3b) Gecko/20030119 Description of problem: Two problems with gcc-3.2-7 1. gcc miscompiles my code (which might be a bordercase but is accepted with all other compilers i've tested against) 2. gcc issues a warning in non-optimizing mode but not when -O is present. Stupid example is below ... --- a.c --- #include <stdio.h> #include <ctype.h> #include <stdlib.h> int main(int argc, char *argv[]) { char *p; p = argv[1]; while(*p) *p++ = toupper(*p); printf("%s\n", argv[1]); return 0; } --- end a.c --- $ cc -Wall a.c a.c: In function `main': a.c:11: warning: operation on `p' may be undefined $ ./a.out hallo HALLO $ cc -Wall -O a.c ./a.out hallo ALLO Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: see above Additional info: