gcc/testsuite/gcc.dg/pr35430.c

/* PR c/35430 */
/* { dg-do compile } */
/* { dg-options "-Wsign-compare" } */

void
foo (__complex__ int i)
{
  i == 0u;
  i == ~1u;	/* { dg-warning "comparison of integer expressions of different signedness" } */
}