J3/01-160

Date:    05 March 2001
To:      J3
From:    Malcolm Cohen
Subject: Revised Interp 00085

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NUMBER: 000085
TITLE: Public components of private types
KEYWORDS: Accessibility, Derived Types, Components
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTION:

F90 interpretation 32 indicated that components of a derived type
may be accessible even in scopes where the derived type name is
inaccessible.  It added an edit to 12.1.2.2.1 of f90 (14.6.1.3 of
f95) saying
  "If a derived type name of a host is inaccessible, data entities of
   that type or subobjects of such data entities can still be
   accessible."

The discussions in the last 2 paragraphs of 4.4.1 of f95 appear to
treat the accessibility of the derived type and its components
as independent issues.  Drafts of f2k added a note to make the
independence clear.

However, 14.1.2.5 of f95 says "If the type is accessible...and the
definition of the type does not contain the PRIVATE statement
(4.4.1), the component name is accessible...."  This statement
appears to make accessibility of the type a condition for
accessibility of the component names, in contradiction with the
above cited edit from f90 interpretation 32.

The following code sample illustrates the issue.  This sample works
on several f90 compilers.

  module m
    type t
      integer :: i
    end type t
    type (t) :: a
  end module m

  program p
    use m, only: a
    a%i = 2
    write (*,*) a%i
  end program p

Question 1.  Is it allowed to access public components of a derived
type object when the type name is inaccessible as illustrated in the
above sample code?

Question 2.  Should there be an edit in 14.1.2.5 of f95 to clarify
this?

ANSWER: (1) Yes.
        (2) Yes.

DISCUSSION:

The quoted text from 14.1.2.5 does not specify the accessibility
of components when a type is not accessible.

EDIT:

[280:25-26] Replace
              "the type is accessible ... 14.6.1.3)"
            by
              "an entity of the type is accessible in another scoping unit"
{Whether by use or host association, or - if the type is accessible - by
declaring a local variable of the type.}

SUBMITTED BY: Richard Maine
HISTORY: 99-101      m148   Submitted
         WG5/N1404          Draft answer
         00-260      m154   Passed by J3 meeting
         00-329      m155   Failed J3 letter ballot
         156-mjc-004 m156   Revised.

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