https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113887
--- Comment #4 from Jens Gustedt <jens.gustedt at inria dot fr> --- (In reply to Joseph S. Myers from comment #2) This is not about the question if the C library supports these types as `uint128_t`. This is primarily to provide `printf` etc *interface* support for the builtin type by means of the new C23 specifiers. C compiler and C library should be independent on this as much as possible, because all combinations of old/new compile/library should work without problems. The musl implementation of the length specifiers does for example not rely any compiler support for the types. It only uses a convention on how to pass 128 bit types as `va_arg` and which of the two 64 halves is high and which is low. For the format checker in the compiler this just asks: - accept w128 and wf128 specifiers iff the platform supports 128 bit integer types - check if the corresponding argument has such a type
