[Bug c/69835] New: [6 Regression] -Wnonnull diagnoses parameter comparisons with NULL even when those could have changed

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69835

            Bug ID: 69835
           Summary: [6 Regression] -Wnonnull diagnoses parameter
                    comparisons with NULL even when those could have
                    changed
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: jakub at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

-Wnonnull warns even about:
static void f(const char *s)
{
  do {
    printf("%s\n",s);
    s = NULL;
  } while (s != NULL);
}
which is wrong, after the parameter has been changed or could have been
changed, it is completely valid to compare it against NULL.