[Bug c/33873] New: Bad printf warning for bitfield

[ian at airs dot com]

Consider this C code:

#include <stdio.h>

typedef long long int int64;
typedef long long unsigned int uint64;

struct pointer {
  uint64 data : 58;
  uint64 tag  : 6;
};


union value {
  int64 i;
  struct pointer p;
};

typedef union value Value;

void test(Value x) {
  printf("%llu\n", x.p.data);
}

When I compile it with -Wall, I get

foo.c:20: warning: format ‘%llu’ expects type ‘long long unsigned int’, but
argument 2 has type ‘long long unsigned int:58’

The value is presumably going to be passed to printf as an unsigned long
long--what else could it be passed as?  So this warning seems incorrect.

This may be related to PR 33819.


-- 
           Summary: Bad printf warning for bitfield
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ian at airs dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33873