[Bug c/95588] New: No warning in -Wformat for narrowing formats

[nhuck at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95588

            Bug ID: 95588
           Summary: No warning in -Wformat for narrowing formats
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nhuck at google dot com
  Target Milestone: ---

When using formats that cause narrowing conversion gcc does not output any
warnings with -Wformat.

//No warning
#include <stdio.h>
void go(int x) {
    printf("%hhx", x);
}

This seems like a valid case for a warning.

Discussion on related issues:
https://lkml.org/lkml/2019/4/11/639
https://github.com/ClangBuiltLinux/linux/issues/378