[Bug c/53232] No warning for main() without a return statement with -std=c99

[vincent-gcc at vinc17 dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53232

--- Comment #14 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
Anyway, as I said initially, the warning would be interesting even in C99+
mode, because the lack of a return statement may be unintentional. For
instance, the developer may have forgotten a "return err;".