Re: Warning specifically for a returning noreturn

[Julian Waters <tanksherman27@gmail.com>]

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Hi Andrew, thanks for the quick response,

What if the method has a return value? I know it sounds counterintuitive,
but in some places HotSpot relies on the noreturn attribute being applied
to methods that do return a value in an unreachable code path. Does the
unreachable builtin cover that case too?

best regards.
Julian

On Wed, Jul 5, 2023 at 9:07 AM Andrew Pinski <pinskia@gmail.com> wrote:

> On Tue, Jul 4, 2023 at 5:54 PM Julian Waters via Gcc <gcc@gcc.gnu.org>
> wrote:
> >
> > Hi all,
> >
> > Currently to disable the warning that a noreturn method does return, it's
> > required to disable warnings entirely. This can be very inconvenient when
> > -Werror is enabled with a noreturn method that isn't specifically calling
> > something like std::abort() at the end, when one wants all other -Wall
> and
> > -Wextra warnings to be reported, for instance in the Java HotSpot VM
> (which
> > I'm currently adapting to compile with gcc on all supported platforms).
> Is
> > there a possibility we can add a disable warning option specifically for
> > this case? Something like -Wno-returning-noreturn. I'm interested in
> adding
> > this myself if it's not convenient for gcc's maintainers to do so at the
> > moment, but I'd need some guidance on where to look and what the relevant
> > code is
>
> You could just add
> __builtin_unreachable(); (or std::unreachable(); if you are C++23 or
> unreachable() if you are using C23).
> Or even add while(true) ;
>
> I am pretty sure not having an option is on purpose and not really
> interested in adding an option here because of the above workarounds.
>
> Thanks,
> Andrew Pinski
>
> >
> > best regards,
> > Julian
>