J3/13-305
To:      J3
From:    Van Snyder
Subject: Interp concerning the IMPORT statement
Date:    2013 August 13

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NUMBER: TBD
TITLE: IMPORT statement and prior explicit declaration
KEYWORD: IMPORT statement, prior explicit declaration
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTIONS:

Does the following program fragment conform to the 2008 standard?

  module M
    interface
      subroutine Q ( X )
        real, intent(inout) :: X
      end subroutine Q
    end interface
  end module M

  subroutine S ( P )
    use M
    interface
      subroutine P ( A )
        import
        procedure (R) :: A
      end subroutine P
    end interface
    procedure (Q) :: R
  end subroutine S

12.4.3.3p2 says "If an entity that is made accessible by this means is
accessed by host association and is defined in the host scoping unit, it
shall be explicitly declared prior to the interface body."

The external procedure R, and therefore its explicit specific interface,
are accessed by host association within the interface body, but neither
one is defined in the host scoping unit.  Therefore, this fragment
appears to conform.

A similar question would be raised concerning 12.4.3.3p1 if the IMPORT
statement were "import :: R", or if subroutine S were a module procedure
within module M instead of accessing module M by use association.

ANSWER:

Since R is declared, but not defined, within the host scoping unit of
the interface body, albeit after the interface body, the program
fragment does conform to the 2008 standard.  It was intended that such
forward references do not conform.

Edits are provided to correct this defect.

EDITS:

[12.4.3.3p1 282:7-8] Replace "An entity that is imported in this manner
and is defined in the host scoping unit shall be explicitly declared
prior to the interface body" with "If an entity that is made accessible
by this means is accessed by host association, it shall be accessible by
use or host association in the host scoping unit, or explicitly defined
or declared prior to the interface body".

{Revised wording is parallel to revised 12.4.3.3p2 (below), instead of
being confusingly dissimilar.}

[12.4.3.3p2 282:13-15] Replace "If an entity that is made accessible by
this means is accessed by host association and is defined in the host
scoping unit, it shall be explicitly declared prior to the interface
body" with "If an entity that is made accessible by this means is
accessed by host association, it shall be accessible by use or host
association in the host scoping unit, or explicitly defined or declared
prior to the interface body".

SUBMITTED BY: Van Snyder

HISTORY: m202  13-xxx  Submitted

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