[Bug fortran/54224] Warn for unused internal procedures

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54224

--- Comment #27 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> At some moment, the Fortran FE sets DECL_SOURCE_LOCATION() on a tree,
> probably using loc->lb->line. Finding out where this happens probably
> requires a bit of debugging.

/* Set the backend source location of a decl.  */

void
gfc_set_decl_location (tree decl, locus * loc)
{
  DECL_SOURCE_LOCATION (decl) = loc->lb->location;
}

in gcc/fortran/trans-decl.c?