[Bug fortran/103054] New: [f18] Gfortran accepts invalid and rejects valid co_reduce argument keyword name

["damian at sourceryinstitute dot org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103054

            Bug ID: 103054
           Summary: [f18] Gfortran accepts invalid and rejects valid
                    co_reduce argument keyword name
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: damian at sourceryinstitute dot org
  Target Milestone: ---

In TS 18508, the second summy argument to co_reduce had the keyword name
"operator."  In the Fortran 2018 standard, the corresponding argument has the
name "operation."  GFortran accepts the non-standard keyword argument name
"operator" and rejects the standard name "operation."

% cat co_reduce.f90 
  implicit none
  logical :: co_all= .true.
  call co_reduce(co_all, operator=both)
  call co_reduce(co_all, operation=both)
contains
  logical pure function both(lhs,rhs)
    logical, intent(in) :: lhs, rhs
    both = lhs .and. rhs
  end function
end

⌁74% [rouson:~] % gfortran -fcoarray=single co_reduce.f90 
co_reduce.f90:4:40:

    4 |   call co_reduce(co_all, operation=both)
      |                                        1
Error: Cannot find keyword named 'operation' in call to 'co_reduce' at (1)
% gfortran --version
GNU Fortran (Homebrew GCC 11.2.0) 11.2.0