https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92821
--- Comment #8 from Emilio Cobos Álvarez (:emilio) <emilio at crisal dot io> --- (In reply to Jakub Jelinek from comment #6) > Note that for most types one ends up with zero or sign extension already due > to C/C++ promotion rules, though in the ABI still can't use that as > guarantee, but C++ typed enums aren't promoted. I see. Another point that someone made in the Mozilla bug tracker is that the ABI, in the "Scalar Types" table, specifies that enums are represented as a `signed fourbyte`. I'm not sure that applies to typed enums. But just in case, if it does, the ABI may require sign/zero-extending these too? Looking at https://bugs.llvm.org/show_bug.cgi?id=12207, which might be a dupe of the LLVM bug I just filed, doesn't make me very hopeful of LLVM changing their behavior here. Would it make sense to make gcc always zero/sign-extend on the caller, even if not required by the ABI or the language? This makes a bunch of calls from gcc to llvm-compiled binaries potentially unsafe.
