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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/110437] SIGILL when return missing in a C++ function with a
 condition
Date: Wed, 28 Jun 2023 08:32:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110437

--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jan =C5=BDi=C5=BEka from comment #12)
> Another example pointed out by one colleague of mine:
>=20
> int f(int a)
> {
>   if (a =3D=3D 1)
>     exit(0);

exit is marked noreturn so the compiler knows this function never reaches t=
he
end without returning. But a user-defined function like "log_and_exit" might
not be marked noreturn, so the same argument applies there. The code is
correct, but the compiler can't prove it, so it can't give an error by defa=
ult.


> That is true :-) but from software implementation if you reuse such a
> function or it is a library I'd personally disallow this as this is bad
> coding. But this will be opinionated so better not to dive to such a rabb=
it
> hole.

Right, the C++ standard isn't based on opinions. If you want to disallow it,
you can use -Werror=3Dreturn-type. That can't be the default though.=