To: J3                                                     J3/14-149r1
From: R. Bader
Subject: Amendments to TS 29113
Date: 2014 June 19
References: N1942, N2014

Based on implementation experience by Tobias Burnus and further comments
by Daniel Chen, Bill Long and others, this paper suggests amendments
to TS 29113. It is an updated version of 13-261. Edits are written
against N2014 (14-007r1).

(A) Assumed rank entities
~~~~~~~~~~~~~~~~~~~~~~~~~

The Fortran lower bounds of an assumed-rank dummy argument that does
not have the POINTER or ALLOCATABLE attribute should be one; some words
on bounds and extents are missing for assumed-rank entities. Furthermore,
C533 must be loosened in order to allow assumed-rank entities to
have the POINTER or ALLOCATABLE attribute.

EDITS:

[97:29] after "ALLOCATABLE attribute" add
" that is not an assumed-rank entity (5.3.8.7)"

[99:20+] After C540, add a new paragraph at the end of 5.3.8.7

"The lower bounds of an assumed-rank entity that does not have the
 POINTER or ALLOCATABLE attribute and is of rank larger than zero
 are 1; its extents and upper bounds are determined as if it were
 an assumed-shape array (5.3.8.3).
 The size, bounds and shape of an assumed-rank entity that has the
 POINTER or ALLOCATABLE attribute and is of rank larger than zero are
 determined as if it were a deferred-shape array (5.3.8.4)."

[[For a corresponding C descriptor, [442:42] already specifies
  the lower bounds for a non-allocatable non-pointer array as zero.]]


(B) Descriptors for assumed size objects
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Descriptors for assumed size objects according to section 15.5.2 have
a dim[].extent value of -1. For some of the functions from section
15.5.5, it is unclear to which extent such descriptors can appear as
parameters. In detail,

(B.1) CFI_address
~~~~~~~~~~~~~~~~~

From the present definition, no valid subscripts[] argument can be
specified for an assumed-size object. This is too draconian.

EDITS:

[447:1-2] Replace "The value of" by
"For <i> between 1 and <n> - 1, the value of"

[447:2+] Add
"The value of subscripts[n] shall be greater than or equal to that
 of the lower bound of dimension <n> specified by the dim member of
 the C descriptor."

[[The last paragraph of 15.7 provides the additional necessary
  restriction that renders any kind of overindexing that may otherwise
  happen non-conforming.]]


(B.2) CFI_select_part
~~~~~~~~~~~~~~~~~~~~~

The /source/ parameter is presently permitted to be an assumed-size
object, resulting in assumed-size subobjects that are in general
non-contiguous. This must be prohibited.

EDIT:

[452:7] After "nonallocatable nonpointer array", add
" that is not assumed-size".


(B.3) CFI_setpointer
~~~~~~~~~~~~~~~~~~~~

The /source/ parameter is presently permitted to be an assumed-size
object. This must be prohibited.

EDIT:

[453:4] After "nonallocatable nonpointer data object", add
" that is not an assumed-size array".


(B.4) Assumed shape dummy matching
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

An assumed-size object must not appear as an actual argument associated
with an assumed-shape dummy. 12.5.2.4 para 14 specifies this for Fortran,
but I consider it useful to add text that confirms this for the
interoperation case.

EDIT:

[453:34-] At the end of 15.6, add the following text

"Because an assumed-size object is prohibited from appearing as an
actual argument associated with an assumed-shape dummy argument
(12.5.2.4), a descriptor for an assumed-size object is not permitted
to appear as an actual parameter corresponding to an assumed shape
dummy argument."


(C) Descriptor updates not uniquely defined
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

For the functions CFI_section and CFI_select_part, it is not clear
how the /lower_bound/ values are set. It is suggested to retain
the pre-existing values.

(C.1) CFI_section

EDITS:

[450:27] Replace "Successful execution ... dim members" by
"Successful execution of CFI_section updates the /base_addr/ and the
 /extent/ and /sm/ members for each array dimension".

The Example Case(ii) needs some minor fixes:

[451:32,33,35] Replace ".lower" by ".lower_bound", thrice.


(C.2) CFI_select_part

EDITS:

[452:16]: Replace the sentence "Successful execution ... members" by

"Successful execution of CFI_select_part updates the /base_addr/ member,
 the /extent/ and /sm/ members for each array dimension and, in case
 /result->type/ specifies a Fortran character type, the /elem_len/
 member"


(D) Allow scalars to be argument associated with assumed-size TYPE(*)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This has been dealt with via 13-283. However I suggest a change to
an example in Annex C.11.7:

EDITS:

[542:8] replace "[ z ]" by "z".

[542:9-10] replace ", but it is necessary ... pass it" by
"; the scalar z is treated as if it were a sequence associated
 array of size one."


(E) Token for assumed-rank entities.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The sequence of two dots should be listed as a token in section 3.2.1
of the Fortran standard, to prevent a declaration of the form

real, dimension(. .) :: a

EDIT:

[44:10] After ";", add ", .."