[Bug tree-optimization/87144] New: missing -Wformat for mismatched argument type

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87144

            Bug ID: 87144
           Summary: missing -Wformat for mismatched argument type
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

GCC fails to diagnose the argument mismatch below.  -Wformat runs too early to
detect it but the snprintf pass could do it.

$ cat f.c && gcc -O2 -S -Wall f.c
int f (_Bool str, int x, const char *s)
{
  const char *f = str ? "%s" : "%i";

  // Note the typo in the ternary operator below: it should be
  //   str ? s : x);
  // instead.
  return __builtin_snprintf (0, 0, f, s ? str : x);
}