https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108694
--- Comment #3 from Aaron Ballman <aaron at aaronballman dot com> --- (In reply to Bruno Haible from comment #2) > But '-Wdeprecated-non-prototype' does not exactly have the behaviour you > want: while it warns for 'func1 (1);' and 'func3 (3);' (good!), it warns > also for 'void func3 ();', that is, where you don't want to see a warning. FWIW, the reason you get a warning on the declaration of `func3` in Clang is because of the definition of `func3` that is invalid in C2x but was valid in prior standards modes. If you do not provide a problematic conflicting definition, the diagnostic is silenced: https://godbolt.org/z/aMPrvWz1j
