[Bug c++/52299] New: GCC warns on compile time division by zero erroneously

["joseph.h.garvin at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52299

             Bug #: 52299
           Summary: GCC warns on compile time division by zero erroneously
    Classification: Unclassified
           Product: gcc
           Version: 4.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: joseph.h.garvin@gmail.com


Test case:

template<std::size_t x>
struct test {
  static const std::size_t a_
  = x ? 10 / x : 10;
};

Output from compiling:

alignptrtest.cpp: In instantiation of ‘const size_t test<0ul>::a_’:
alignptrtest.cpp:11:   instantiated from here
alignptrtest.cpp:6: warning: division by zero

The warning should be suppressed when zero is explicitly checked for. At
runtime this could require fancy analysis that might be unreasonable to expect,
but since this is compile time it should be possible to know whether the
division by 0 really occurs. Especially since it's smart enough to give the
warning even when dividing by (x+1-1).