[Bug middle-end/39390] New: [4.4 regression] Bogus aliasing warning with std::set

[reichelt at gcc dot gnu dot org]

Another problem with aliasing: The following code snippet triggers a bogus
warning when compiled on trunk with "-O -Wall":

==========================================================================
#include<set>

struct A
{
  A() : i() {}
  int i;
};

struct B
{
  bool operator() (const A& x, const A& y) const { return x.i < y.i; }
};

void foo()
{
  std::set<A, B> s;
  s.insert(A());
}
==========================================================================

bug.cc: In function 'void foo()':
bug.cc:11: warning: dereferencing pointer '__x.15' does break strict-aliasing
rules
.../gcc-4.4-20090305/include/c++/4.4.0/bits/stl_tree.h:530: note: initialized
from here
bug.cc:11: warning: dereferencing pointer '__x.15' does break strict-aliasing
rules
.../gcc-4.4-20090305/include/c++/4.4.0/bits/stl_tree.h:530: note: initialized
from here

This probably results in wrong code generation.


-- 
           Summary: [4.4 regression] Bogus aliasing warning with std::set
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: wrong-code, diagnostic
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: reichelt at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39390