https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80666
Dominique d'Humieres <dominiq at lps dot ens.fr> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |WAITING Last reconfirmed| |2017-05-08 Ever confirmed|0 |1 --- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> --- Why do you think this a bug in gfortran? The code compiles if you remove 'implicit none'. With it you have to define 'keylen' before using it, as in you second test.