To: J3                                                     J3/19-194r1
From: Daniel Chen
Subject: C_F_POINTER modification for feature UK-01
Date: 2019-August-05

Reference: WG5/N2167, 18-007r1

Introduction
------------

UK feature for F202X in WG5/N2167: UK-01

A pointer assignment allows an array pointer to have lower bounds
other than 1. Intrinsic subroutine C_F_POINTER does not. This
paper proposes adding an optional argument to C_F_POINTER to allow
that.


Edits to 18-007r1
----------------

[xiii] Introduction
Add "The subroutine C_F_POINTER in the intrinsic module ISO_C_BINDING
has an extra optional dummy argument, LOWER that specifies the lower
bounds of FPTR."

[470:13] Subclause 18.2.3.3 C_F_POINTER (CPTR, FPTR [, SHAPE])
replace "[, SHAPE]" by "[, SHAPE, LOWER]"

The line now reads:
18.2.3.3 C_F_POINTER (CPTR, FPTR [, SHAPE, LOWER])


[470:24-25] Subclause 18.2.3.3 C_F_POINTER (CPTR, FPTR [, SHAPE])
replace
" and each lower bound is equal to 1." by
"; the lower bounds are specified by LOWER if it is present, and
otherwise are equal to 1."

The line now reads:
"If FPTR is an array, its shape is specified by SHAPE; the lower
bounds are specified by LOWER if it is present, and otherwise
are equal to 1."


[471:21-22] Subclause 18.2.3.3 C_F_POINTER (CPTR, FPTR [, SHAPE])
In Case (iii), replace " and each lower bound is 1" to
"; the lower bounds are specified by LOWER if it is
present, and otherwise are equal to 1."

The line now reads:
"If FPTR is an array, its shape is specified by SHAPE; the lower
bounds are specified by LOWER if it is present, and otherwise
are equal to 1."


[471:26+] Subclause 18.2.3.3 C_F_POINTER (CPTR, FPTR [, SHAPE])
After the definition of SHAPE, add:
"LOWER (optional) shall be a rank-one integer array. It is an
        INTENT (IN) argument. It shall not be present if SHAPE
        is not present. If LOWER is present, its size
        shall be equal to the rank of FPTR."


[471:37-45] Examples.
replace Case (ii) by:
"
  Type t
    Real, Allocatable :: v(:,:)
  End Type
  Type(t), Target :: x(0:2)
  Type(C_ptr) :: xloc
  xloc = C_Loc (x)
  ...
  Type(t), Pointer :: y (:)
  Call C_F_Pointer (xloc, y, [3], [0])
"