[Bug c/17257] New: Some assignment operators do not trigger "assignment used as * truth value" warning

[tlambert2 at mindspring dot com]

/*
 * Some assignment operators do not trigger "assignment used as
 * truth value" warning.  This seems wrong.  The following code,
 * when compiled with "-Wall" only causes the compiler to emit a
 * single warning, only for the direct assignment.  The same effect
 * is present on Macintosh (gcc 3.3 PPC) and Linux x86 platforms.
 */

#include <stdio.h>
#include <stdlib.h>

extern void opaque_func(int *ip, int *jp);	/* avoid const optimization */

int
main(int ac, char *av[])
{
	int i = 3;
	int j = 1;

	if( i = j) {
		printf(" i and j the same\n");
	}

	opaque_func(&i, &j);

	if (i |= j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i &= j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i += j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i -= j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i *= j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i /= j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i ^= j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i %= j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i <<= j) {
		printf("non-zero\n");
	}

	opaque_func(&i, &j);

	if (i >>= j) {
		printf("non-zero\n");
	}

	exit(0);
}


void
opaque_func(int *ip, int *jp)
{
	*ip += 2;
	*jp += 3;
}

-- 
           Summary: Some assignment operators do not trigger "assignment
                    used as * truth value" warning
           Product: gcc
           Version: 3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tlambert2 at mindspring dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: gcc version 3.3.3 [FreeBSD] 20031106
  GCC host triplet: gcc version 3.3.3 [FreeBSD] 20031106
GCC target triplet: gcc version 3.3.3 [FreeBSD] 20031106


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17257