[Bug fortran/125383] [14/15/16/17 Regression] Optional dummy procedure called from contained subprogram results in linking error since r16-3178 / r14-12039

[albert at tugraz dot at]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125383

--- Comment #11 from Christopher Albert <albert at tugraz dot at> ---
Created attachment 65180
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65180&action=edit
0001-fortran-Preserve-host-association-for-dummy-procedur.patch

Require a known procedure kind before a provisional subroutine attribute
counts as a declaration. This preserves host association for the optional
dummy procedure and avoids the undefined external symbol. A run test covers
absent and present callbacks. check-fortran and the libgomp Fortran suites
are clean.