* [Bug c++/8057] [3.4/4.0/4.1 regression] Templates/non-templates and warnings about statements without effects
[not found] <bug-8057-180@http.gcc.gnu.org/bugzilla/>
@ 2005-10-10 19:39 ` ian at airs dot com
2005-10-10 19:44 ` mark at codesourcery dot com
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From: ian at airs dot com @ 2005-10-10 19:39 UTC (permalink / raw)
To: gcc-bugs
------- Comment #10 from ian at airs dot com 2005-10-10 19:39 -------
I think Mark's analysis is somewhat misleading for this particular warning,
since this warning actually is issued by the frontend. It comes from
convert_to_void in cp/cvt.c.
--
ian at airs dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ian at airs dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8057
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[not found] <bug-8057-180@http.gcc.gnu.org/bugzilla/>
2005-10-10 19:39 ` [Bug c++/8057] [3.4/4.0/4.1 regression] Templates/non-templates and warnings about statements without effects ian at airs dot com
@ 2005-10-10 19:44 ` mark at codesourcery dot com
2005-10-11 22:34 ` mark at codesourcery dot com
` (5 subsequent siblings)
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From: mark at codesourcery dot com @ 2005-10-10 19:44 UTC (permalink / raw)
To: gcc-bugs
------- Comment #11 from mark at codesourcery dot com 2005-10-10 19:44 -------
Subject: Re: [3.4/4.0/4.1 regression] Templates/non-templates
and warnings about statements without effects
ian at airs dot com wrote:
> ------- Comment #10 from ian at airs dot com 2005-10-10 19:39 -------
> I think Mark's analysis is somewhat misleading for this particular warning,
> since this warning actually is issued by the frontend. It comes from
> convert_to_void in cp/cvt.c.
Oh, dear. Yes, I agree; if the warning is coming from the front-end, it
must be the front-end's responsibility to fix, and my opinions about
warnings from the middle end are not relevant.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8057
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[not found] <bug-8057-180@http.gcc.gnu.org/bugzilla/>
2005-10-10 19:39 ` [Bug c++/8057] [3.4/4.0/4.1 regression] Templates/non-templates and warnings about statements without effects ian at airs dot com
2005-10-10 19:44 ` mark at codesourcery dot com
@ 2005-10-11 22:34 ` mark at codesourcery dot com
2005-10-11 22:37 ` ian at airs dot com
` (4 subsequent siblings)
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From: mark at codesourcery dot com @ 2005-10-11 22:34 UTC (permalink / raw)
To: gcc-bugs
------- Comment #12 from mark at codesourcery dot com 2005-10-11 22:33 -------
Subject: Re: [3.4/4.0/4.1 regression] Templates/non-templates
and warnings about statements without effects
With the proposed patch, what happens with something like:
template <typename T>
void f() {
T(); /* Has side-effects only if T is a class type. */
}
In general, I'm concerned about warning only at template-declaration
time because I don't think we can be sure we can see all side effects at
that point. I think it would be more reliable (and more consistent with
the overall approach in G++) to warn only in the instantiations.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8057
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[not found] <bug-8057-180@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2005-10-11 22:34 ` mark at codesourcery dot com
@ 2005-10-11 22:37 ` ian at airs dot com
2005-10-11 22:46 ` mark at codesourcery dot com
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From: ian at airs dot com @ 2005-10-11 22:37 UTC (permalink / raw)
To: gcc-bugs
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------- Comment #13 from ian at airs dot com 2005-10-11 22:37 -------
With your suggested test case, and my suggested patch, you will get the warning
foo.cc: In function ‘void f()’:
foo.cc:3: warning: value computed is not used
It's easy to emit the warning only for template instantiations and not for
template declarations. That wasn't my first choice because it means that you
will get a warning each time the template is instantiated.
I will submit a new patch.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8057
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[not found] <bug-8057-180@http.gcc.gnu.org/bugzilla/>
` (3 preceding siblings ...)
2005-10-11 22:37 ` ian at airs dot com
@ 2005-10-11 22:46 ` mark at codesourcery dot com
2005-10-11 23:27 ` mark at codesourcery dot com
` (2 subsequent siblings)
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From: mark at codesourcery dot com @ 2005-10-11 22:46 UTC (permalink / raw)
To: gcc-bugs
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------- Comment #14 from mark at codesourcery dot com 2005-10-11 22:46 -------
Subject: Re: [3.4/4.0/4.1 regression] Templates/non-templates
and warnings about statements without effects
ian at airs dot com wrote:
> ------- Comment #13 from ian at airs dot com 2005-10-11 22:37 -------
> With your suggested test case, and my suggested patch, you will get the warning
>
> foo.cc: In function ‘void f()’:
> foo.cc:3: warning: value computed is not used
>
> It's easy to emit the warning only for template instantiations and not for
> template declarations. That wasn't my first choice because it means that you
> will get a warning each time the template is instantiated.
Yes, that's annoying -- but I think it's more accurate overall.
You should also feel free to argue with me; I'm not trying to be a dictator.
> I will submit a new patch.
Thanks.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8057
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[not found] <bug-8057-180@http.gcc.gnu.org/bugzilla/>
` (4 preceding siblings ...)
2005-10-11 22:46 ` mark at codesourcery dot com
@ 2005-10-11 23:27 ` mark at codesourcery dot com
2005-10-11 23:31 ` cvs-commit at gcc dot gnu dot org
2005-10-11 23:33 ` ian at airs dot com
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From: mark at codesourcery dot com @ 2005-10-11 23:27 UTC (permalink / raw)
To: gcc-bugs
------- Comment #15 from mark at codesourcery dot com 2005-10-11 23:27 -------
Subject: Re: [3.4/4.0/4.1 regression] Templates/non-templates
and warnings about statements without effects
This patch is OK, thanks!
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8057
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[not found] <bug-8057-180@http.gcc.gnu.org/bugzilla/>
` (5 preceding siblings ...)
2005-10-11 23:27 ` mark at codesourcery dot com
@ 2005-10-11 23:31 ` cvs-commit at gcc dot gnu dot org
2005-10-11 23:33 ` ian at airs dot com
7 siblings, 0 replies; 8+ messages in thread
From: cvs-commit at gcc dot gnu dot org @ 2005-10-11 23:31 UTC (permalink / raw)
To: gcc-bugs
------- Comment #16 from cvs-commit at gcc dot gnu dot org 2005-10-11 23:31 -------
Subject: Bug 8057
CVSROOT: /cvs/gcc
Module name: gcc
Changes by: ian@gcc.gnu.org 2005-10-11 23:30:57
Modified files:
gcc/cp : ChangeLog cvt.c
gcc/testsuite : ChangeLog
gcc/testsuite/g++.dg/warn: noeffect2.C noeffect4.C
Added files:
gcc/testsuite/g++.dg/warn: noeffect7.C
Log message:
cp/
PR c++/8057
* cvt.c (convert_to_void): Don't warn about unused values when
processing a template declaration.
testsuite/
PR c++/8057
* g++.dg/warn/noeffect7.C: New test.
* g++.dg/warn/noeffect2.C: Instantiate templates.
* g++.dg/warn/noeffect4.C: Instantiate template. Add new error
and warning.
Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&r1=1.4920&r2=1.4921
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/cvt.c.diff?cvsroot=gcc&r1=1.187&r2=1.188
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.6169&r2=1.6170
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/warn/noeffect7.C.diff?cvsroot=gcc&r1=NONE&r2=1.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/warn/noeffect2.C.diff?cvsroot=gcc&r1=1.1&r2=1.2
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/warn/noeffect4.C.diff?cvsroot=gcc&r1=1.1&r2=1.2
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8057
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[not found] <bug-8057-180@http.gcc.gnu.org/bugzilla/>
` (6 preceding siblings ...)
2005-10-11 23:31 ` cvs-commit at gcc dot gnu dot org
@ 2005-10-11 23:33 ` ian at airs dot com
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From: ian at airs dot com @ 2005-10-11 23:33 UTC (permalink / raw)
To: gcc-bugs
------- Comment #17 from ian at airs dot com 2005-10-11 23:33 -------
Fixed on mainline. I don't think there is any compelling need to backport this
minor warning patch to the 4.0 or 3.4 branches.
--
ian at airs dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8057
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