On Thu, 12 Jul 2018 at 19:01, Pedro Alves <pal...@redhat.com> wrote: > > On 07/12/2018 05:17 PM, Richard Sandiford wrote: > > Pedro Alves <pal...@redhat.com> writes: > > >> (an > >>> alternative to pointers is to return a struct with the wide int result > >>> and the overflow flag), > >> > >> +1. I've been pushing GDB in that direction whenever possible. > > > > I agree that can sometimes be better. I guess it depends on the > > context. If a function returns a bool and some other data that has no > > obvious "failure" value, it can be easier to write chained conditions if > > the function returns the bool and provides the other data via an output > > parameter. > > I agree it depends on context, though your example sounds like a > case for std::optional<T>. (We have gdb::optional<T> in gdb, since > std::optional is C++17 and gdb requires C++11. LLVM has a similar > type, I believe.)
Yes I agree. optional<T> foo (); void bar (const T&); if (optional<T> val = foo ()) bar (*val); Or expected<T> which is a union of T and an error flag (and a discriminator value to tell you which union member is active). That also allows chaining in a similar way. Forgetting to test whether the optional/expected holds a value before trying to use that value would be an ICE.
