Dear all,

Jose posted a patch here that was never reviewed:

  https://gcc.gnu.org/pipermail/fortran/2021-June/056162.html

I think the diagnostics improvement is helpful, as it adjusts
to the changes from F2003 to F2008.

The patch suffered a little from bitrot, but was otherwise
straightforward to apply.  I slightly edited the commit
message, as I found the original one difficult to parse.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald