[Bug c++/121368] [[nodiscard]] warning not triggered when discarding return value from function pointer call

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121368

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Yan from comment #0)
> g++ -std=c++17 -Wall -Wextra -Wunused -O0

You are not using g++, you are using clang pretending to be g++ because that's
how it's installed on macOS.