public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
* [Bug c/65423] New: No warning on always-true/false predicates containing bitwise operations @ 2015-03-14 9:45 chengniansun at gmail dot com 2015-03-14 18:11 ` [Bug c/65423] " mpolacek at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: chengniansun at gmail dot com @ 2015-03-14 9:45 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65423 Bug ID: 65423 Summary: No warning on always-true/false predicates containing bitwise operations Product: gcc Version: 5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: chengniansun at gmail dot com The condition "(a & 9) == 4" is always false, and it will be great if Gcc can emit a warning on this. $: cat bitwise.c int f(int a) { if ((a & 9) == 4) { return 1; } else { return 0; } } $: clang-trunk -Wtautological-compare -c bitwise.c bitwise.c:2:15: warning: bitwise comparison always evaluates to false [-Wtautological-compare] if ((a & 9) == 4) { ~~~~~~~~^~~~ 1 warning generated. $: gcc-trunk -Wall -Wextra -Wtype-limits -c bitwise.c ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/65423] No warning on always-true/false predicates containing bitwise operations 2015-03-14 9:45 [Bug c/65423] New: No warning on always-true/false predicates containing bitwise operations chengniansun at gmail dot com @ 2015-03-14 18:11 ` mpolacek at gcc dot gnu.org 2015-03-15 9:17 ` maltsevm at gmail dot com 2015-03-16 15:47 ` mpolacek at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: mpolacek at gcc dot gnu.org @ 2015-03-14 18:11 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65423 Marek Polacek <mpolacek at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |mpolacek at gcc dot gnu.org --- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> --- Yes, that would be nice. I think we already have such a bug report, though. I'll look for it later. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/65423] No warning on always-true/false predicates containing bitwise operations 2015-03-14 9:45 [Bug c/65423] New: No warning on always-true/false predicates containing bitwise operations chengniansun at gmail dot com 2015-03-14 18:11 ` [Bug c/65423] " mpolacek at gcc dot gnu.org @ 2015-03-15 9:17 ` maltsevm at gmail dot com 2015-03-16 15:47 ` mpolacek at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: maltsevm at gmail dot com @ 2015-03-15 9:17 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65423 Mikhail Maltsev <maltsevm at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |maltsevm at gmail dot com --- Comment #2 from Mikhail Maltsev <maltsevm at gmail dot com> --- Probably this one: PR17534 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/65423] No warning on always-true/false predicates containing bitwise operations 2015-03-14 9:45 [Bug c/65423] New: No warning on always-true/false predicates containing bitwise operations chengniansun at gmail dot com 2015-03-14 18:11 ` [Bug c/65423] " mpolacek at gcc dot gnu.org 2015-03-15 9:17 ` maltsevm at gmail dot com @ 2015-03-16 15:47 ` mpolacek at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: mpolacek at gcc dot gnu.org @ 2015-03-16 15:47 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65423 Marek Polacek <mpolacek at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |DUPLICATE --- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> --- Dup. *** This bug has been marked as a duplicate of bug 17534 *** ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-03-16 15:47 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-03-14 9:45 [Bug c/65423] New: No warning on always-true/false predicates containing bitwise operations chengniansun at gmail dot com 2015-03-14 18:11 ` [Bug c/65423] " mpolacek at gcc dot gnu.org 2015-03-15 9:17 ` maltsevm at gmail dot com 2015-03-16 15:47 ` mpolacek at gcc dot gnu.org
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).