To: J3                                                     11-113r1
From: John Reid/Bill Long
Subject: Interop: UTI TR3
Date: 2011 February 16
References: N1838, N1844, ISO/IEC 1539-1:2010

DISCUSSION

Unresolved Technical Issue TR3 of N1838 points out that people want the
rank field of CFI_cdesc_t to match the RANK intrinsic. The first two
solutions suggested are

(1) fold the character length into elem_len (which, unless we add
    support for wchar_t, would be equal to the value of elem_len).
(2) add an additional character length member.

Both of these are favoured by those expressing an opinion in N1844.
Bill Long gave clear reasons for option (1), so I have constructed
edits for this. As far as I can see, the same edits would be needed
for option (2), with the addition of edits for the additional member.
These could always be added at a later date if they are deemed
necessary.

I am encouraged to think that this is the right solution by the fact
that the edits involve the deletion of two paragraphs and the addition
of a note that was in any case requested by Reinhold Bader in N1844.

Note that if this is accepted, TR2 becomes mute.

EDITS to N1838:

[9:30] In 5.2.2 CFI_cdesc_t, para 1, line for size_t elem_len, replace
"equal to the sizeof() of an element of the object"

by

"if an object corresponding to a Fortran CHARACTER object with length
not equal to one, the value equals the length of the CHARACTER object
times the sizeof() of a scalar of the character type; otherwise the
value equals the sizeof() of an element of the object."


[9:33] In 5.2.2 CFI_cdesc_t, para 1, line for CFI_rank_t rank, replace
the first occurrence of
"object"
by
"Fortran object".

[10:9] In 5.2.2 CFI_cdesc_t, para 1, line for CFI_dim_t dim[], replace
the first occurrence of
"object"
by
"Fortran object".

[10:10+] In 5.2.2 CFI_cdesc_t, at the end of the subclause, add

"NOTE 5.0

If the type of the Fortran object is character with kind C_CHAR, the
value of the elem_len member shall be equal to the character length. A
Fortran character array is permitted to interoperate with a
multidimensional C array whose last dimension is a character array of
size equal to the value of elem_len.  For example, a Fortran array
declared as CHARACTER(KIND=C_CHAR, LEN=20) A(30,40) can be associated
with a Fortran dummy argument declared as CHARACTER(KIND=C_CHAR)
X(20,30,40), which is interoperable with a C array declared as char b
[40] [30] [20]."

[10:20-24] In 5.2.3 CFI_dim_t, delete para 2. [There is no longer anything
exceptional about character type.]

[16:19] In 5.2.7 Restrictions on the use of C descriptors, delete para 4.