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* [Bug c++/39875] New: [4.5 regression] Wrong "value computed is not used" warning
@ 2009-04-23 19:59 bangerth at gmail dot com
2009-04-24 9:25 ` [Bug c++/39875] " rguenth at gcc dot gnu dot org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: bangerth at gmail dot com @ 2009-04-23 19:59 UTC (permalink / raw)
To: gcc-bugs
I think this is from after 4.4 branched:
----------------------
template <typename TT> struct InputIterator
{
InputIterator ()
{
TT i;
(void)*i; // require dereference operator
}
};
InputIterator<int *> i;
---------------------
> c++ -c deal.II/source/dofs/dof_renumbering.cc -W -Wall
deal.II/source/dofs/dof_renumbering.cc: In constructor
'InputIterator<TT>::InputIterator() [with TT = int*]':
deal.II/source/dofs/dof_renumbering.cc:10: instantiated from here
deal.II/source/dofs/dof_renumbering.cc:6: warning: value computed is not used
That's obviously bogus, the compiler warns about a statement that is
explicitly cast to 'void' so there is no computed value any more.
The code is culled from boost's concepts checks, so this is going to hit
quite a number of people.
W.
--
Summary: [4.5 regression] Wrong "value computed is not used"
warning
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: bangerth at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39875
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/39875] [4.5 regression] Wrong "value computed is not used" warning 2009-04-23 19:59 [Bug c++/39875] New: [4.5 regression] Wrong "value computed is not used" warning bangerth at gmail dot com @ 2009-04-24 9:25 ` rguenth at gcc dot gnu dot org 2009-04-26 17:11 ` bangerth at gmail dot com ` (4 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: rguenth at gcc dot gnu dot org @ 2009-04-24 9:25 UTC (permalink / raw) To: gcc-bugs -- rguenth at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Target Milestone|--- |4.5.0 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39875 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/39875] [4.5 regression] Wrong "value computed is not used" warning 2009-04-23 19:59 [Bug c++/39875] New: [4.5 regression] Wrong "value computed is not used" warning bangerth at gmail dot com 2009-04-24 9:25 ` [Bug c++/39875] " rguenth at gcc dot gnu dot org @ 2009-04-26 17:11 ` bangerth at gmail dot com 2009-04-26 19:23 ` jakub at gcc dot gnu dot org ` (3 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: bangerth at gmail dot com @ 2009-04-26 17:11 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from bangerth at gmail dot com 2009-04-26 17:10 ------- May be related to PR 39889. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39875 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/39875] [4.5 regression] Wrong "value computed is not used" warning 2009-04-23 19:59 [Bug c++/39875] New: [4.5 regression] Wrong "value computed is not used" warning bangerth at gmail dot com 2009-04-24 9:25 ` [Bug c++/39875] " rguenth at gcc dot gnu dot org 2009-04-26 17:11 ` bangerth at gmail dot com @ 2009-04-26 19:23 ` jakub at gcc dot gnu dot org 2009-04-26 19:36 ` jakub at gcc dot gnu dot org ` (2 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: jakub at gcc dot gnu dot org @ 2009-04-26 19:23 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from jakub at gcc dot gnu dot org 2009-04-26 19:23 ------- No need for templates: void foo () { int *i; (void) *i; // { dg-bogus "value computed is not used" } } This was caused by http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=146132 (PR39551). convert_to_void doesn't know if the conversion to void was caused by explicit cast (in this testcase, no warning should be emitted) or implicit (when it should be emitted). -- jakub at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |lcwu at gcc dot gnu dot org Status|UNCONFIRMED |NEW Ever Confirmed|0 |1 Last reconfirmed|0000-00-00 00:00:00 |2009-04-26 19:23:28 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39875 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/39875] [4.5 regression] Wrong "value computed is not used" warning 2009-04-23 19:59 [Bug c++/39875] New: [4.5 regression] Wrong "value computed is not used" warning bangerth at gmail dot com ` (2 preceding siblings ...) 2009-04-26 19:23 ` jakub at gcc dot gnu dot org @ 2009-04-26 19:36 ` jakub at gcc dot gnu dot org 2009-04-27 5:54 ` jakub at gcc dot gnu dot org 2009-04-27 5:56 ` jakub at gcc dot gnu dot org 5 siblings, 0 replies; 7+ messages in thread From: jakub at gcc dot gnu dot org @ 2009-04-26 19:36 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from jakub at gcc dot gnu dot org 2009-04-26 19:36 ------- Created an attachment (id=17732) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17732&action=view) gcc45-pr39875.patch Actually, convert_to_void knows that, see the implicit argument. -- jakub at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- AssignedTo|unassigned at gcc dot gnu |jakub at gcc dot gnu dot org |dot org | Status|NEW |ASSIGNED http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39875 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/39875] [4.5 regression] Wrong "value computed is not used" warning 2009-04-23 19:59 [Bug c++/39875] New: [4.5 regression] Wrong "value computed is not used" warning bangerth at gmail dot com ` (3 preceding siblings ...) 2009-04-26 19:36 ` jakub at gcc dot gnu dot org @ 2009-04-27 5:54 ` jakub at gcc dot gnu dot org 2009-04-27 5:56 ` jakub at gcc dot gnu dot org 5 siblings, 0 replies; 7+ messages in thread From: jakub at gcc dot gnu dot org @ 2009-04-27 5:54 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from jakub at gcc dot gnu dot org 2009-04-27 05:54 ------- Subject: Bug 39875 Author: jakub Date: Mon Apr 27 05:54:32 2009 New Revision: 146825 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=146825 Log: PR c++/39875 * cvt.c (convert_to_void) <case INDIRECT_REF>: Only warn about -Wunused-value if implicit. * g++.dg/warn/Wunused-15.C: New test. Added: trunk/gcc/testsuite/g++.dg/warn/Wunused-15.C Modified: trunk/gcc/cp/ChangeLog trunk/gcc/cp/cvt.c trunk/gcc/testsuite/ChangeLog -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39875 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/39875] [4.5 regression] Wrong "value computed is not used" warning 2009-04-23 19:59 [Bug c++/39875] New: [4.5 regression] Wrong "value computed is not used" warning bangerth at gmail dot com ` (4 preceding siblings ...) 2009-04-27 5:54 ` jakub at gcc dot gnu dot org @ 2009-04-27 5:56 ` jakub at gcc dot gnu dot org 5 siblings, 0 replies; 7+ messages in thread From: jakub at gcc dot gnu dot org @ 2009-04-27 5:56 UTC (permalink / raw) To: gcc-bugs ------- Comment #5 from jakub at gcc dot gnu dot org 2009-04-27 05:55 ------- Fixed. -- jakub at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Resolution| |FIXED http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39875 ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2009-04-27 5:56 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2009-04-23 19:59 [Bug c++/39875] New: [4.5 regression] Wrong "value computed is not used" warning bangerth at gmail dot com 2009-04-24 9:25 ` [Bug c++/39875] " rguenth at gcc dot gnu dot org 2009-04-26 17:11 ` bangerth at gmail dot com 2009-04-26 19:23 ` jakub at gcc dot gnu dot org 2009-04-26 19:36 ` jakub at gcc dot gnu dot org 2009-04-27 5:54 ` jakub at gcc dot gnu dot org 2009-04-27 5:56 ` jakub at gcc dot gnu dot org
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