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* [Bug c++/54047] New: unused variable warning not for std::string @ 2012-07-20 11:52 plasmahh at gmx dot net 2012-07-20 12:09 ` [Bug c++/54047] " redi at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: plasmahh at gmx dot net @ 2012-07-20 11:52 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54047 Bug #: 54047 Summary: unused variable warning not for std::string Classification: Unclassified Product: gcc Version: 4.8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned@gcc.gnu.org ReportedBy: plasmahh@gmx.net Compiling the following code: #include <string> struct A { }; void foo() { A z; std::string z0; } I get a warning for unused variable z, but not for variable z0. It seems that std::string is somehow magical here, but I can't see how or why. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/54047] unused variable warning not for std::string 2012-07-20 11:52 [Bug c++/54047] New: unused variable warning not for std::string plasmahh at gmx dot net @ 2012-07-20 12:09 ` redi at gcc dot gnu.org 2012-07-20 14:08 ` daniel.kruegler at googlemail dot com 2013-06-07 9:26 ` paolo.carlini at oracle dot com 2 siblings, 0 replies; 4+ messages in thread From: redi at gcc dot gnu.org @ 2012-07-20 12:09 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54047 Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |diagnostic --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-07-20 12:09:01 UTC --- It's the case for all objects with a non-trivial constructor, not only std::string. Constructors might have side-effects, so you might not need to "use" the variable, all you want is to construct it. e.g. you don't want an unused variable warning for 'l' here: void f(std::mutex& m, int& i) { std::lock_guard<std::mutex> l(m); i = 1; } I think this behaviour is intentional and correct. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/54047] unused variable warning not for std::string 2012-07-20 11:52 [Bug c++/54047] New: unused variable warning not for std::string plasmahh at gmx dot net 2012-07-20 12:09 ` [Bug c++/54047] " redi at gcc dot gnu.org @ 2012-07-20 14:08 ` daniel.kruegler at googlemail dot com 2013-06-07 9:26 ` paolo.carlini at oracle dot com 2 siblings, 0 replies; 4+ messages in thread From: daniel.kruegler at googlemail dot com @ 2012-07-20 14:08 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54047 Daniel Krügler <daniel.kruegler at googlemail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |daniel.kruegler at | |googlemail dot com --- Comment #2 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2012-07-20 14:07:55 UTC --- (In reply to comment #1) > I think this behaviour is intentional and correct. I completely agree with that. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/54047] unused variable warning not for std::string 2012-07-20 11:52 [Bug c++/54047] New: unused variable warning not for std::string plasmahh at gmx dot net 2012-07-20 12:09 ` [Bug c++/54047] " redi at gcc dot gnu.org 2012-07-20 14:08 ` daniel.kruegler at googlemail dot com @ 2013-06-07 9:26 ` paolo.carlini at oracle dot com 2 siblings, 0 replies; 4+ messages in thread From: paolo.carlini at oracle dot com @ 2013-06-07 9:26 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54047 Paolo Carlini <paolo.carlini at oracle dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> --- Closing. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-06-07 9:26 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-07-20 11:52 [Bug c++/54047] New: unused variable warning not for std::string plasmahh at gmx dot net 2012-07-20 12:09 ` [Bug c++/54047] " redi at gcc dot gnu.org 2012-07-20 14:08 ` daniel.kruegler at googlemail dot com 2013-06-07 9:26 ` paolo.carlini at oracle dot com
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