[Bug fortran/82865] Option -fdec collides with PDT

[jvdelisle at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82865

--- Comment #4 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> ---
I would be OK with a hard error. If so, we need to think about any other
similir situations with other modern fortran features. Then we get into a game
of chasing more rabits. Perhaps best to document and just say that -fdec it is
known to be incompatible with some constructs such as PDT and should not be
mixed with modern fortran.