J3/13-239
To: J3
From: Malcolm Cohen
Subject: Interp F08/0085
Date: 2013 February 11

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NUMBER: F08/0085
TITLE: Problems with PARAMETERs
KEYWORDS: PARAMETER
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTION:

(1) Consider the program fragment

    Subroutine s
      Parameter (n=1)
      Integer :: x,n       !(A)
      Parameter (x=3)

    The type declaration statement marked "!(A)", declares the
    entities X and N to be of type INTEGER.  Furthermore, as we see by
    the immediately preceding and following PARAMETER statements, both
    X and N are named constants.

    Unfortunately, a constraint says
      C507 (R503) "An <initialization> shall appear if the entity is a
                   named constant (5.3.13)."
    (BTW, R503 is <entity-decl>.)

    Therefore one concludes that the type declaration statement marked
    "!(A)" is not conforming as it violates C507 for both X and N.

    Is this statement intended to be conforming?

(2) Firstly, consider

    Subroutine s2(n)
      Integer,Parameter :: x(n:n+1) = [ 1,2 ]
      Character(n),Parameter :: y = 'abc'
      ...

    The type declaration statements are not conforming because
    according to 5.2.2p1, X and Y are automatic data objects, and C506
    says that <initialization> shall not appear in that case.

    Now consider

    Subroutine s2b(n)
      Implicit Character(n) (a-z)
      Parameter (y = 'abc')
      Integer :: x(n:n+1)
      Parameter(x=[1,2])

    This is not valid Fortran 2003, because 5.2 contains the
    requirement:
      "The combination of attributes that may be specified for a
       particular entity is subject to the same restrictions as for
       type declaration statements regardless of the method of
       specification.  This also applies to PROCEDURE, EXTERNAL, and
       INTRINSIC statements."

    This requirement does not appear in F2008.  However, there is no
    indication in the Introduction of this new feature.

    Is this extension to Fortran 2003 deliberate?

ANSWER:

(1) Yes, the type declaration statement was intended to be allowed.
    An edit is supplied to correct this mistake.

(2) No, the omission of this requirement was inadvertent.  An edit
    is supplied to correct this mistake.

EDITS:

[88:14] In 5.2.1, Replace constraint "C507 (503)" completely with
  "C507 (R501) If the PARAMETER keyword appears, <initialization>
        shall appear in each <entity-decl>."
{Fix Q1.}

[88:14+] In 5.2.1, immediately after constraint C507, insert new
         constraint:
  "C507a An expression that specifies a length type parameter or
         array bound of a named constant shall be a constant
         expression."
{Fix Q2.}

SUBMITTED BY: Malcolm Cohen

HISTORY: 12-189    m199  F08/0085 submitted
         12-189r1  m199  Passed by J3 meeting
         13-237    m200  Failed as amended by J3 letter ballot
                          #27 13-203
         13-nnn    m200  Revised

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