To: J3                                                     J3/26-200
From: Malcolm Cohen
Subject: Interp F23/021 on pointers in COMMON and SIMPLE procedures
Date: 2026-October-16


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NUMBER: F23/021
TITLE: May a simple procedure depend on common pointer association?
KEYWORDS: POINTER, COMMON, ASSOCIATED, SIMPLE
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress
REFERENCES: 24-007

QUESTION:

Consider
    SIMPLE SUBROUTINE example(x)
      LOGICAL,INTENT(INOUT) :: x
      COMMON/C/p
      REAL,POINTER :: p
      x = ASSOCIATED(p)
    END SUBROUTINE

Is this conforming?

Constraint C15116 "A simple subprogram shall not contain a reference
                   to a variable in a common block."
is ineffective, as appearing in ASSOCIATED is not a reference.

However, a pointer accessed by use or host association cannot have its
pointer association status queried in this way in a simple procedure
(constraint C15115 is effective, as it only permits inquiry function
references that are constant expressions).

That indicates that this example was probably not intended to be
conforming.

ANSWER:

The example was not intended to be conforming.
Simple procedures should not depend on nonlocal variables in this way.

EDITS to 24-007:

The best fix is probably to include variables in common in C15115
which is not defective, and to delete the defective C15116. This can
be done without renumbering the rest of the constraints (such
renumbering would be appropriate in the next revision, not in a
corrigendum).

[348:6] 15.8 Simple procedures, constraint C15115,
        after "shall not contain a designator"
        insert "\obs{of a variable in a common block, or}",
        making the whole constraint read:
   "C15115 A simple subprogram shall not contain a designator of a
           variable in a common block, or of a variable that is
           accessed by use or host association, unless the designator
           is part of a specification inquiry (10.1.11) that is a
           constant expression."

[348:8] Same subclause, delete constraint C15116 which reads
   "C15116 A simple subprogram shall not contain a reference to a
           variable in a common block."

SUBMITTED BY: Malcolm Cohen

HISTORY: 26-nnn   m241  Submitted

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