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* [Bug c++/94745] New: No error emitted for unknown -Wno-meow argument @ 2020-04-24 13:25 ldionne.2 at gmail dot com 2020-04-24 13:34 ` [Bug c++/94745] " redi at gcc dot gnu.org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: ldionne.2 at gmail dot com @ 2020-04-24 13:25 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94745 Bug ID: 94745 Summary: No error emitted for unknown -Wno-meow argument Product: gcc Version: 10.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: ldionne.2 at gmail dot com Target Milestone: --- GCC does not diagnose unsupported -Wno-meow command line flags unless another error happens during compilation. For example, the following compiles just fine even though -Wno-foo doesn't exist: $ echo | g++ -xc++ - -Werror -fsyntax-only -Wno-foo <nothing> If, however, another error happens during compilation, the unsupported command-line flag is reported: $ echo '#error' | g++ -xc++ - -Werror -fsyntax-only -Wno-foo <stdin>:1:2: error: #error cc1plus: error: unrecognized command line option '-Wno-foo' [-Werror] cc1plus: all warnings being treated as errors This makes detecting whether GCC supports a given warning flag very challenging in build systems. This issue popped up while trying to support GCC when running the libc++ Standard Library conformance test suite. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/94745] No error emitted for unknown -Wno-meow argument 2020-04-24 13:25 [Bug c++/94745] New: No error emitted for unknown -Wno-meow argument ldionne.2 at gmail dot com @ 2020-04-24 13:34 ` redi at gcc dot gnu.org 2020-04-24 13:36 ` redi at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: redi at gcc dot gnu.org @ 2020-04-24 13:34 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94745 --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- This is by design. It means that makefiles written for different versions of GCC do not trigger spurious diagnostics. If somebody says "I don't want warnings about cat noises" and their version of GCC doesn't support -Wmeow then their request is granted. Warning about it would cause valid compilations to fail. If other diagnostics are being emitted anyway, then adding one to point out the unrecognized option isn't going to make a build go from passing to failing. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/94745] No error emitted for unknown -Wno-meow argument 2020-04-24 13:25 [Bug c++/94745] New: No error emitted for unknown -Wno-meow argument ldionne.2 at gmail dot com 2020-04-24 13:34 ` [Bug c++/94745] " redi at gcc dot gnu.org @ 2020-04-24 13:36 ` redi at gcc dot gnu.org 2020-04-24 17:42 ` rguenth at gcc dot gnu.org 2020-05-04 14:38 ` ldionne.2 at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: redi at gcc dot gnu.org @ 2020-04-24 13:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94745 --- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Louis Dionne from comment #0) > This makes detecting whether GCC supports a given warning flag very > challenging in build systems. You're doing it wrong then. Try 'g++ -Q --help=warnings' instead of probing individual options. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/94745] No error emitted for unknown -Wno-meow argument 2020-04-24 13:25 [Bug c++/94745] New: No error emitted for unknown -Wno-meow argument ldionne.2 at gmail dot com 2020-04-24 13:34 ` [Bug c++/94745] " redi at gcc dot gnu.org 2020-04-24 13:36 ` redi at gcc dot gnu.org @ 2020-04-24 17:42 ` rguenth at gcc dot gnu.org 2020-05-04 14:38 ` ldionne.2 at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu.org @ 2020-04-24 17:42 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94745 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |WONTFIX Status|UNCONFIRMED |RESOLVED --- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- If you want to detect whether a warning is supported use -Wfoo, not -Wno-foo. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/94745] No error emitted for unknown -Wno-meow argument 2020-04-24 13:25 [Bug c++/94745] New: No error emitted for unknown -Wno-meow argument ldionne.2 at gmail dot com ` (2 preceding siblings ...) 2020-04-24 17:42 ` rguenth at gcc dot gnu.org @ 2020-05-04 14:38 ` ldionne.2 at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: ldionne.2 at gmail dot com @ 2020-05-04 14:38 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94745 --- Comment #4 from Louis Dionne <ldionne.2 at gmail dot com> --- Thanks for your replies, all. We resolved the problem on our side by not trying to workaround the lack of error, which means that we might end up passing `-Wno-foo` to GCC when it's not supported. I think that follows the design intent explained by Jonathan. Thanks again! ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-05-04 14:38 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-04-24 13:25 [Bug c++/94745] New: No error emitted for unknown -Wno-meow argument ldionne.2 at gmail dot com 2020-04-24 13:34 ` [Bug c++/94745] " redi at gcc dot gnu.org 2020-04-24 13:36 ` redi at gcc dot gnu.org 2020-04-24 17:42 ` rguenth at gcc dot gnu.org 2020-05-04 14:38 ` ldionne.2 at gmail dot com
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