[Bug fortran/35033] New: Valid ASSIGNMENT(=) rejected

[burnus at gcc dot gnu dot org]

To my understanding, the interface declaration is valid (Fortran 2003, ignoring
VOLATILE valid Fortran 95). However, gfortran rejects it with:

             END SUBROUTINE
                          1
Error: Assignment operator interface at (1) must not redefine an INTRINSIC type
assignment

NAG f95, ifort and openf95 accept it.

 * * *

>From the F2003 interpretations comes also the part below. Here, gfortran fails
to diagnose the violation of the constrain

"C1233 (R1221) If an actual argument is a pointer array, and the corresponding
dummy argument has either the VOLATILE or ASYNCHRONOUS attribute, that dummy
argument shall be an assumed-shape array or a pointer array."
(see below).

Example (see N1711.txt / F03/0088):

          INTERFACE ASSIGNMENT(=)
             SUBROUTINE s(a,b)
                 REAL,INTENT(OUT),VOLATILE :: a(1,*)
                 REAL,INTENT(IN) :: b(:)
             END SUBROUTINE
          END Interface
          REAL,POINTER :: p(:,:),q(:)
          CALL s(p,q)    ! Violation of constraint C1233 [271:9-11],
                         !  associating P with A
          p = q          ! No constraint violation because <actual-arg>
                         !  syntax is not being used
          end


>From the interpretation request (F03/0088, passed by J3, to be voted on by W5):

QUESTION:

  Did Fortran 2003 intend to enforce constraints on <actual-arg> in
  defined assignment?

ANSWER:

 Yes, the <actual-arg> constraints and restrictions should be enforced
 in defined assignment and in defined operator evaluation.

 Edits are provided below to do this.

EDITS:

  [262:16] add at the end of the paragraph
   "All restrictions and constraints that apply to actual arguments
    in a reference to the function also apply to the corresponding
    operands in the expression as if they were used as actual arguments."

  [263:12] insert after "the second argument."
   "All restrictions and constraints that apply to actual arguments
    in a reference to the subroutine also apply to the left-hand-side
    and to the right-hand-side enclosed in parentheses as if they were


-- 
           Summary: Valid ASSIGNMENT(=) rejected
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35033