On Wed, 5 Jul 2023 at 12:01, Julian Waters via Gcc <gcc@gcc.gnu.org> wrote: > > I see, thanks Andrew. > > Anyone else have opinions on this besides Liu or Andrew? The responses have > been surprisingly quiet thus far
IMHO all warnings should have an option controlling them, so that you can disable them via pragmas. But I agree that you shouldn't need to return from a noreturn function, it can either throw or use __builtin_unreachable() on the line where you currently return. > > best regards, > Julian > > On Wed, 5 Jul 2023, 09:40 Andrew Pinski, <pins...@gmail.com> wrote: > > > On Tue, Jul 4, 2023 at 6:32 PM Julian Waters <tanksherma...@gmail.com> > > wrote: > > > > > > 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? > > > > It is wrong to use noreturn on a function other than one which has a > > return type of void as documented. > > > > https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute > > : > > ``` > > It does not make sense for a noreturn function to have a return type > > other than void. > > ``` > > > > Thanks, > > Andrew Pinski > > > > > > > > > > best regards. > > > Julian > > > > > > On Wed, Jul 5, 2023 at 9:07 AM Andrew Pinski <pins...@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 > >
