[Bug libstdc++/40156] New: [4.4 Regression] Possible bogus warning in libstdc++ headers

[Bug libstdc++/40156] New: [4.4 Regression] Possible bogus warning in libstdc++ headers

[tbm at cyrius dot com]

I'm getting the following warning when compiling wesnoth.  I'm not sure if
this is a bug in the code or in GCC but Andrew Pinski said I should file a
bug so someone can take a look at it.

This happens with gcc 4.4, but not with 4.3.

(sid)700:tbm@em64t: ~/src/wesnoth-1.6.2/src] g++-4.4 -c -O1 -Wall -Werror
game_preferences.ii
cc1plus: warnings being treated as errors
game_preferences.cpp: In constructor 'preferences::manager::manager()':
game_preferences.cpp:66: error: 'v.std::vector<std::basic_string<char,
std::char_traits<char>, std::allocator<char> >,
std::allocator<std::basic_string<char, std::char_traits<char>,
std::allocator<char> > >
>::<anonymous>.std::_Vector_base<std::basic_string<char,
std::char_traits<char>, std::allocator<char> >,
std::allocator<std::basic_string<char, std::char_traits<char>,
std::allocator<char> > > >::_M_impl.std::_Vector_base<std::basic_string<char,
std::char_traits<char>, std::allocator<char> >,
std::allocator<std::basic_string<char, std::char_traits<char>,
std::allocator<char> > > >::_Vector_impl::_M_start' may be used uninitialized
in this function
game_preferences.cpp:70: error: 'terrain.std::vector<t_translation::t_terrain,
std::allocator<t_translation::t_terrain>
>::<anonymous>.std::_Vector_base<t_translation::t_terrain,
std::allocator<t_translation::t_terrain>
>::_M_impl.std::_Vector_base<t_translation::t_terrain,
std::allocator<t_translation::t_terrain> >::_Vector_impl::_M_start' may be used
uninitialized in this function
zsh: exit 1     g++-4.4 -c -O1 -Wall -Werror game_preferences.ii


-- 
           Summary: [4.4 Regression] Possible bogus warning in libstdc++
                    headers
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tbm at cyrius dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug libstdc++/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[tbm at cyrius dot com]

------- Comment #1 from tbm at cyrius dot com  2009-05-15 08:10 -------
Created an attachment (id=17872)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17872&action=view)
Preprocessed code


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[paolo dot carlini at oracle dot com]

------- Comment #2 from paolo dot carlini at oracle dot com  2009-05-15 09:02 -------
Definitely bogus, maybe we already have something open about this issue, CC-ing
Richard, to be sure...


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
          Component|libstdc++                   |middle-end


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[manu at gcc dot gnu dot org]

------- Comment #3 from manu at gcc dot gnu dot org  2009-05-15 09:11 -------
Does it happen on trunk?

The testcase is too big.


-- 

manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |manu at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2009-05-15 09:17 -------
It is an uninitialized use in an exception handler.

;; basic block 132, loop depth 0, count 0
;; prev block 131, next block 133
;; pred:       131 (ab,eh,exec)
;; succ:       135 [100.0%]  (fallthru,exec)
<L49>:
save_filt.2381_159 = [filter_expr] <<<filter object>>>;
save_eptr.2380_160 = [exc_ptr_expr] <<<exception object>>>;
ivtmp.6668_667 = (long unsigned int) v$D45569$_M_impl$_M_start_645(D);
goto <bb 135>;

possibly reached from

;; basic block 116, loop depth 0, count 0
;; prev block 115, next block 117
;; pred:       115 [100.0%]  (fallthru,exec)
;; succ:       131 (ab,eh,exec) 117 [100.0%]  (fallthru,exec)
<bb 116>:
D.141736 = get (&D.141735); [return slot optimization]


we could avoid warning for these at all but I am not sure if that would
be appreciated.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[jsm28 at gcc dot gnu dot org]

-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.4.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[manu at gcc dot gnu dot org]

------- Comment #5 from manu at gcc dot gnu dot org  2009-06-18 16:28 -------
(In reply to comment #4)
> It is an uninitialized use in an exception handler.

Is it an explicit exception handler? Or a compiler-generated?

In any case, it looks like the code is actually executed, so it may well be a
bug in the code.


-- 

manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
OtherBugsDependingO|                            |24639
              nThis|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[manu at gcc dot gnu dot org]

------- Comment #6 from manu at gcc dot gnu dot org  2009-06-18 16:30 -------
This is marked as a 4.4 regression. Does it happen in trunk?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[paolo dot carlini at oracle dot com]

------- Comment #7 from paolo dot carlini at oracle dot com  2009-06-18 17:19 -------
Today I can't reproduce it neither with mainline nor with 4_4-branch.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156

[Bug middle-end/40156] [4.4 Regression] Possible bogus warning in libstdc++ headers

[manu at gcc dot gnu dot org]

------- Comment #8 from manu at gcc dot gnu dot org  2009-07-08 13:28 -------
I am going to close this as FIXED, since it cannot be reproduced anymore. If
anyone manages to reproduce it in GCC 4.5, please reopen.


-- 

manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40156