[Bug c++/19457] New: Warning depends on cached constant

[reichelt at gcc dot gnu dot org]

Mainline's C++ frontend warns about the following code snippet:

======================
int i=-1;
unsigned int j= ~0;
======================

warn.cc:2: warning: converting of negative value '-0x000000001' to
'unsigned int'

The strange thing is that the warning disappears if I comment out the
unrelated first line or change the value for "i" to "-2". Looks like
the cached constant determines the type of the new constant.

I'd expect "~0" to be signed and "~0u" to be unsigned, so I think the
warning is correct, but I'm not sure.

But in either case, the warning should not depend on some cached constant.

Btw, what about the constant 0xffffffff? Should a warning appear when
is's assigned to a signed or an unsigned int?

-- 
           Summary: Warning depends on cached constant
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: reichelt at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19457