https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57871
--- Comment #8 from Dominique d'Humieres <dominiq at lps dot ens.fr> --- > The reason I sent that bug report is that I had read the manual and > found that -freal-4-real-16 makes the available real kinds 8, 10, 16. > The Fortran standard says selected_real_kind(1) must give the kind with > the smallest available decimal precision that has precison at least 1. > In the circumstances that is kind 8. The manual refers to promotion of > REAL(KIND=M) entities. Selected_real_kind is an integer entity not a > real one. AFAIU this is based on the expectation that the conversion options act as a "pre-processor", i.e., take place before the compilation really starts. The results show that expectation is not true and that the options act as a "post-processor", i.e., the code is compiled as if the option was not provided, then the conversion takes place. selected_real_kind is probably the only function that can show the difference. IMO this should be documented and the PR closed as WONTFIX.
