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* [Bug c++/55203] New: No unused warning for variables of non-trivial types
@ 2012-11-04 10:48 l.lunak at suse dot cz
2012-11-04 11:04 ` [Bug c++/55203] " l.lunak at suse dot cz
` (9 more replies)
0 siblings, 10 replies; 11+ messages in thread
From: l.lunak at suse dot cz @ 2012-11-04 10:48 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
Bug #: 55203
Summary: No unused warning for variables of non-trivial types
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: l.lunak@suse.cz
GCC warns about unused variables e.g. of type 'int', but not 'std::string' :
$ cat a.cpp
#include <string>
void foo()
{
int i;
std::string s;
}
$ g++ -Wall -Wunused -c a.cpp
a.cpp: In function ‘void foo()’:
a.cpp:5:9: warning: unused variable ‘i’ [-Wunused-variable]
int i;
^
In the function 's' is apparently unused too, but the compiler cannot tell it.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
@ 2012-11-04 11:04 ` l.lunak at suse dot cz
2012-11-04 11:05 ` l.lunak at suse dot cz
` (8 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: l.lunak at suse dot cz @ 2012-11-04 11:04 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
Lubos Lunak <l.lunak at suse dot cz> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
--- Comment #1 from Lubos Lunak <l.lunak at suse dot cz> 2012-11-04 11:04:01 UTC ---
As the compiler cannot tell for sure in some cases, such as the ctor calling an
external function, the only reasonable way of handling this I see is explicit
tagging of types for which there should be an unused warning if only ctor/dtor
are called for a variable. Here's my attempt at attribute warn_unused.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
2012-11-04 11:04 ` [Bug c++/55203] " l.lunak at suse dot cz
@ 2012-11-04 11:05 ` l.lunak at suse dot cz
2012-11-07 14:55 ` paolo.carlini at oracle dot com
` (7 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: l.lunak at suse dot cz @ 2012-11-04 11:05 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
--- Comment #2 from Lubos Lunak <l.lunak at suse dot cz> 2012-11-04 11:04:52 UTC ---
Created attachment 28609
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28609
gcc patch
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
2012-11-04 11:04 ` [Bug c++/55203] " l.lunak at suse dot cz
2012-11-04 11:05 ` l.lunak at suse dot cz
@ 2012-11-07 14:55 ` paolo.carlini at oracle dot com
2013-06-15 18:13 ` paolo.carlini at oracle dot com
` (6 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: paolo.carlini at oracle dot com @ 2012-11-07 14:55 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-11-07 14:54:59 UTC ---
Patches should go to gcc-patches. But I'm afraid it's too late for something
like this to make 4.8.0.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
` (2 preceding siblings ...)
2012-11-07 14:55 ` paolo.carlini at oracle dot com
@ 2013-06-15 18:13 ` paolo.carlini at oracle dot com
2013-07-16 6:41 ` l.lunak at suse dot cz
` (5 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: paolo.carlini at oracle dot com @ 2013-06-15 18:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> ---
I guess this could be the right time to properly submit something to
gcc-patches (for 4.9)
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
` (3 preceding siblings ...)
2013-06-15 18:13 ` paolo.carlini at oracle dot com
@ 2013-07-16 6:41 ` l.lunak at suse dot cz
2013-07-16 9:57 ` redi at gcc dot gnu.org
` (4 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: l.lunak at suse dot cz @ 2013-07-16 6:41 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
--- Comment #5 from Lubos Lunak <l.lunak at suse dot cz> ---
Gcc patch is in, r200941.
Keeping open for libstdc++ to use the attribute for its relevant classes. I can
try to submit a patch when I find the time, but I doubt I'll get past the most
obvious classes, so anyone more knowledgeable about libstdc++ can feel free.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
` (4 preceding siblings ...)
2013-07-16 6:41 ` l.lunak at suse dot cz
@ 2013-07-16 9:57 ` redi at gcc dot gnu.org
2013-07-16 9:58 ` redi at gcc dot gnu.org
` (3 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: redi at gcc dot gnu.org @ 2013-07-16 9:57 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Which are the relevant classes? It seems to me that we want to tag almost
everything except a few RAII types such as std::lock_guard and
std::unique_lock, which would be quite tedious. It's certainly applicable on
all containers, and most streams except fstreams (which have constructors with
side-effects.)
I think your extend.texi change is wrong, a std::mutex that is unused is
useless, its constructor and destructor don't do anything useful. A
std::lock_guard that is unused is useless.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
` (5 preceding siblings ...)
2013-07-16 9:57 ` redi at gcc dot gnu.org
@ 2013-07-16 9:58 ` redi at gcc dot gnu.org
2013-07-16 11:29 ` l.lunak at suse dot cz
` (2 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: redi at gcc dot gnu.org @ 2013-07-16 9:58 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #6)
> std::lock_guard that is unused is useless.
Oops, I meant is *not* useless! Sorry.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
` (6 preceding siblings ...)
2013-07-16 9:58 ` redi at gcc dot gnu.org
@ 2013-07-16 11:29 ` l.lunak at suse dot cz
2013-07-16 12:30 ` redi at gcc dot gnu.org
2021-09-15 15:51 ` msebor at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: l.lunak at suse dot cz @ 2013-07-16 11:29 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
--- Comment #8 from Lubos Lunak <l.lunak at suse dot cz> ---
(In reply to Jonathan Wakely from comment #6)
> Which are the relevant classes? It seems to me that we want to tag almost
> everything except a few RAII types such as std::lock_guard and
> std::unique_lock, which would be quite tedious. It's certainly applicable
> on all containers, and most streams except fstreams (which have constructors
> with side-effects.)
Correct. And I do not see a better way than tagging everything where it
applies.
> I think your extend.texi change is wrong, a std::mutex that is unused is
> useless, its constructor and destructor don't do anything useful. A
> std::lock_guard that is unused is *not* useless.
Correct as well. But that doesn't come from my patch, that section was altered
by Jason Merrill before committing, and I overlooked that. Can you fix that
easily or should I submit a patch?
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
` (7 preceding siblings ...)
2013-07-16 11:29 ` l.lunak at suse dot cz
@ 2013-07-16 12:30 ` redi at gcc dot gnu.org
2021-09-15 15:51 ` msebor at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: redi at gcc dot gnu.org @ 2013-07-16 12:30 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I can fix the docs some time.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/55203] No unused warning for variables of non-trivial types
2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
` (8 preceding siblings ...)
2013-07-16 12:30 ` redi at gcc dot gnu.org
@ 2021-09-15 15:51 ` msebor at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: msebor at gcc dot gnu.org @ 2021-09-15 15:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55203
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2021-09-15
Status|UNCONFIRMED |NEW
--- Comment #22 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed as a useful enhancement.
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2021-09-15 15:51 UTC | newest]
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2012-11-04 10:48 [Bug c++/55203] New: No unused warning for variables of non-trivial types l.lunak at suse dot cz
2012-11-04 11:04 ` [Bug c++/55203] " l.lunak at suse dot cz
2012-11-04 11:05 ` l.lunak at suse dot cz
2012-11-07 14:55 ` paolo.carlini at oracle dot com
2013-06-15 18:13 ` paolo.carlini at oracle dot com
2013-07-16 6:41 ` l.lunak at suse dot cz
2013-07-16 9:57 ` redi at gcc dot gnu.org
2013-07-16 9:58 ` redi at gcc dot gnu.org
2013-07-16 11:29 ` l.lunak at suse dot cz
2013-07-16 12:30 ` redi at gcc dot gnu.org
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