[Bug c/37591] New: suppress "signed and unsigned" warnings when signed value known to be positive

["zackw at panix dot com" <gcc-bugzilla at gcc dot gnu dot org>]

In a case such as this, GCC ought to be able to prove that the signed variable
is positive and therefore suppress "signed and unsigned" warnings.  I see this
in both C and C++.

#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define MIN(a,b) ((a) < (b) ? (a) : (b))

unsigned int
constrain(unsigned int index, unsigned int offset, unsigned int limit)
{
  int adj = index - offset;
  adj = MAX(adj, 0);
  return MIN(adj, limit); /* { dg-bogus "signed and unsigned" } */
}


-- 
           Summary: suppress "signed and unsigned" warnings when signed
                    value known to be positive
           Product: gcc
           Version: 4.3.2
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: enhancement
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zackw at panix dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37591