X3J3/96-025
                                                                (Page 1 of 1)
To: X3J3
From: Janice C. Shepherd
Subject: RFI on EXTERNAL submitted by M. Hennecke
Date:  January 19, 1996

NUMBER: 000205
TITLE: Restrictions on EXTERNAL
KEYWORDS: EXTERNAL attribute, external subprogram
DEFECT TYPE:
STATUS: X3J3 consideration in progress

QUESTION: Let the following two procedures not be contained within a main
program, a module, or another subprogram.  In this case they are <<external
subprogram>>s by the definitions of Fortran 90, section 2.2:

  SUBROUTINE subroutine_subprogram ( )
  ! ...
  END SUBROUTINE subroutine_subprogram

  FUNCTION function_subprogram ( )
    INTEGER :: function_subprogram
  ! ...
  END FUNCTION function_subprogram

They are also external procedures, since F90 section 2.2.3.1 (and 12.1.2.2)
states that

   "An <<external procedure>> is a procedure that is defined by an
    external subprogram or by means other than Fortran."

External functions may be given the EXTERNAL attribute in form of an
<attr-spec> (R503), external procedures may be given the EXTERNAL attribute
by an <external-stmt> (R1207)  [F95: R1208].

QUESTION 1: Is it correct that the current definitions in F90 do allow the
EXTERNAL attribute to be specified for the name of the external subprogram in
which such a declaration is contained?  In other words, is the following code
standard-conforming?

  SUBROUTINE subroutine_subprogram ( )
    EXTERNAL subroutine_subprogram
  ! ...
  END SUBROUTINE subroutine_subprogram

  FUNCTION function_subprogram ( )
    INTEGER, EXTERNAL :: function_subprogram
  ! ...
  END FUNCTION function_subprogram

QUESTION 2: If the answer to question 1 is YES: was this the intention, or
should it be prohibited that an EXTERNAL attribute is given to the name of an
external subprogram by declarations within that subprogram?

ANSWER:
EDIT:
SUBMITTED BY: Michael Hennecke (hennecke@rz.uni-karlsruhe.de)
HISTORY: 96-025  m136 submitted