On Thu, 29 Sept 2022 at 08:12, Jakub Jelinek <ja...@redhat.com> wrote: > > On Thu, Sep 29, 2022 at 08:00:15AM +0200, Richard Biener via Gcc wrote: > > On Wed, Sep 28, 2022 at 10:17 PM Jonathan Wakely via Gcc > > <gcc@gcc.gnu.org> wrote: > > > > > > As part of implementing a C++23 proposal [1] to massively increase the > > > scope of the freestanding C++ standard library some questions came up > > > about the special handling of main() that happens for hosted > > > environments. > > > > > > As required by both C++ (all versions) and C (since C99), falling off > > > the end of the main() function is not undefined, the compiler is > > > required to insert an implicit 'return 0' [2][3]. However, this > > > special handling only applies to hosted environments. For freestanding > > > the return type or even the existence of main is > > > implementation-defined. > > ^^^^^^^^^^^^^^^^^^^^^^ > > > > so just document that 'int main(int, char **)' is special to GCC even in > > freestanding environments and do not emit -Wreturn-type diagnostics? > > I think that's entirely reasonable (but of course make sure to add > > an implicit return 0; then as well) > > -fspecial-main is weirdly named, I wonder if we couldn't do the > above by default and have -fno-builtin-main turn that special behavior > off (in that case then don't append return 0 and emit -Wreturn-type > diagnostics). Not all our builtins are about whether we expand them inline, > but > about whether we apply special handling to those functions, assume special > properties etc. Just -fno-builtin shouldn't imply -fno-builtin-main...
Yeah, that sounds like a good compromise. Make int main do the right thing by default, but offer a switch to restore the current behaviour for anybody who really wants it.
