[Bug c++/25649] New: [g++, regression?] Bogus "uninitialized" warning

["martin at mpa-garching dot mpg dot de" <gcc-bugzilla at gcc dot gnu dot org>]

When compiling the code below with current mainline, I get a warning that was
not emitted a few days ago.

#include <iostream>

using namespace std;

int main()
  {
  int x;
  cin >> x;
  cout << x << endl;
  }

martin@linux:~/tmp> g++ -v -Wuninitialized -O bla.cc
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /home/martin/software/gcc/configure --quiet
--prefix=/home/martin/software/ugcc --enable-languages=c++,fortran
--enable-checking=release
Thread model: posix
gcc version 4.2.0 20060102 (experimental)
 /home/martin/software/ugcc/libexec/gcc/x86_64-unknown-linux-gnu/4.2.0/cc1plus
-quiet -v -D_GNU_SOURCE bla.cc -quiet -dumpbase bla.cc -mtune=k8 -auxbase bla
-O -Wuninitialized -version -o /tmp/ccSrl6e0.s
ignoring nonexistent directory
"/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:

/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/../../../../include/c++/4.2.0

/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/../../../../include/c++/4.2.0/x86_64-unknown-linux-gnu

/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/../../../../include/c++/4.2.0/backward
 /usr/local/include
 /home/martin/software/ugcc/include
 /home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/include
 /usr/include
End of search list.
GNU C++ version 4.2.0 20060102 (experimental) (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.2.0 20060102 (experimental).
GGC heuristics: --param ggc-min-expand=98 --param ggc-min-heapsize=127998
Compiler executable checksum: daaafcb7365564947efcbce06b4e70bb
bla.cc: In function ?int main()?:
bla.cc:7: warning: ?x? may be used uninitialized in this function
 as -V -Qy -o /tmp/ccbnSz84.o /tmp/ccSrl6e0.s
GNU assembler version 2.16.91.0.2 (x86_64-suse-linux) using BFD version
2.16.91.0.2 20050720 (SuSE Linux)
 /home/martin/software/ugcc/libexec/gcc/x86_64-unknown-linux-gnu/4.2.0/collect2
--eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2
/usr/lib/../lib64/crt1.o /usr/lib/../lib64/crti.o
/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/crtbegin.o
-L/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0
-L/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/../../../../lib64
-L/lib/../lib64 -L/usr/lib/../lib64
-L/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/../../..
/tmp/ccbnSz84.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc
/home/martin/software/ugcc/lib/gcc/x86_64-unknown-linux-gnu/4.2.0/crtend.o
/usr/lib/../lib64/crtn.o

This warning is not emitted by the current gomp branch, 4.1 branch and 4.0
branch

Is this intended behavior?


-- 
           Summary: [g++, regression?] Bogus "uninitialized" warning
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: martin at mpa-garching dot mpg dot de
 GCC build triplet: x86_64-unknown-linux-gnu
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25649