[Bug c++/57178] New: bogus warning with -O3 using boost::optional

[eda-qa at disemia dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57178

             Bug #: 57178
           Summary: bogus warning with -O3 using boost::optional
    Classification: Unclassified
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: eda...@disemia.com


GCC appears to be producing a bogus warning about an unitialized value. This
happens at optimization levels -O1 and higher. It uses a boost optional as I
was unable to reduce it to something more fundamental.

Command line:

g++ -c uninit_warn.cpp --std=c++0x -Wuninitialized -O1

Warning:
uninit_warn.cpp: In function ‘void test(boost::optional<int>)’:
uninit_warn.cpp:17:12: warning: ‘*((void*)& q +4)’ may be used uninitialised in
this function [-Wuninitialized]