[Bug fortran/104143] New: [F2018] Accept scalar actual arguments to assumed-type assumed-size array dummies [type(*), dimension(*)]

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104143

            Bug ID: 104143
           Summary: [F2018] Accept scalar actual arguments to assumed-type
                    assumed-size array dummies [type(*), dimension(*)]
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

Passing a (non-character) scalar to an assumed-type assumed-size array dummy is
now
permitted - new in Fortran 2018 (see last bullet in the quote below).


Fortran 2008 (12.5.2.4 Ordinary dummy variables):

"... If the actual argument is a noncoindexed scalar, the corresponding dummy
argument
 shall be scalar unless the actual argument is default character, of type
character
 with the C character kind (15.2.2), or is an element or substring of an
element
 of an array that is not an assumed-shape, pointer, or polymorphic array."

Fortran 2018:

"If the actual argument is a noncoindexed scalar, the corresponding dummy
argument
 shall be scalar unless
 • the actual argument is default character, of type character with the C
character kind
   (18.2.2), or is an element or substring of an element of an array that is
not an
   assumed-shape, pointer, or polymorphic array,
 • the dummy argument has assumed-rank, or
 • the dummy argument is an assumed-type assumed-size array."

Example:
 interface
   subroutine foo(x)
     type(*) :: x(*)
   end
 end interface
 integer :: a
 call foo(a)
end

(When a generic interface is used, passing a scalar or array element to an
assumed-size array is not permitted - at least that's how GCC+ifort have
implemented it.)

(The new feature avoids the need to use the '!GCC$ ATTRIBUTES NO_ARG_CHECK'
attribute as workaround.)