https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112498
--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #3)
> Maybe we could add "is not allowed in ISO C++" or similar to the warning.
This has been done for GCC 14:
fp.cc:2:20: warning: ISO C++ does not allow converting to 'std::float16_t' {aka
'_Float16'} from 'float' with greater conversion rank [-Wnarrowing]
