https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77970
--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- I think the correct logic would be something like: if the argument is for a standard typedef, and the format doesn't correspond exactly to that typedef (or one differing only by sign, e.g. allow %ju for an intmax_t unless -Wformat-signedness), warn (with an option to disable it) even if they match (or match up to sign) on this particular system. Likewise if the format is for a standard typedef but the argument isn't. Hard to implement for various reasons (including <inttypes.h> format macros - glibc's definitions of those for intmax_t match the underlying type rather than using "j", for example), and would have false positives in various cases, but more warnings rather than less seems right here and would make warnings more consistent between targets. The option to disable warnings for mismatched typedefs could then have different stringencies for whether it disables even int/long mismatches, or only cases that already wouldn't warn but for the use of standard typedefs.
