To: J3                                                     10-206r1
From: John Reid, Bill Long
Subject: Interop TR: CFI_allocate and CFI_deallocate
Date: 2010 October 13
References: 10-165r2, ISO/IEC 1539-1:2010

DISCUSSION

It is stated in 5.2.6.2 of 10-165r2 that CFI_allocate uses the same
mechanism as the Fortran ALLOCATE statement, but the conditions are not
the same. Similarly, it is stated in 5.2.6.3 that CFI_deallocate uses
the same mechanism at the Fortran DEALLOCATE statement, but the
conditions are not the same. Edits are proposed to correct this.

Furthermore, an edit is proposed to allow the DEALLOCATE statement to
deallocate a pointer target that was allocated by CFI_allocate.

Malcolm Cohen suggests eliminating the state member. He says "Just
requiring the address field to be non-null would be sufficient, and
nicer to use.  Whether the underlying Fortran implementation uses
a null address for zero-sized allocations or not, the right thing
to do is to hide the processor dependency from the user, not expose
it." Edits for this are provided.


EDITS to 10-165r2:

[9:22]. Replace
"If the object has zero size, the value is processor-dependent."
by
"If the object has zero size, the value is not NULL but is otherwise
processor dependent."

[9:35-36]. Delete the lines for int state.
           [Note to editor: Also delete references to CFI_state_t
           introduced by 10-203r2.]

[12:3] Change "On entry, the base address in the C descriptor shall
       be NULL. The" to "On entry, the".

[12:4] Change "disassociated" to "a".

[12:4-5] Change "The supplied" to "On successful execution of
         CFI_allocate, the supplied", and move this sentence to
         be after the sentence at [12:6] ending "... assumed to be
         one."

[12:11] Change "On entry, the base address in the C descriptor shall
       not be NULL. The" to "On entry, the".

[12:12-13] Change "that was allocated ... statement" to
     "satisfying the conditions for successful deallocation by the
     Fortran DEALLOCATE statement (6.7.3.3 of ISO/IEC 1539-1:2010)".

[13] Add a new section:

     5.3 Interaction with the DEALLOCATE statement

     The DEALLOCATE statement shall treat a pointer whose target was
     allocated using CFI_allocate in exactly the same way as if it
     were allocated using an ALLOCATE statement.