J3/04-342

To:      J3
From:    Dan Nagle
Subject: Storage Size of entities
Date:    2004 June 16

One item of unfinished business from f03 is the issue
of a storage size intrinsic usable with (nearly) any type and kind
of argument.

This paper raises some issues:

Should storage_size be an intrinsic procedure, or an intrinsic
module procedure (in iso_fortran_env).  Having storage_size
in the same category as the *_storage_size constants is logical,
but then are any words needed to allow use of storage_size
in compile-time expressions?

This paper is based on N1539, however I have changed the lines
of the edits to acommadate the proposed renumbering
of section 13.8 to separate the constants and procedures
in iso_fortran_env.  Also, N1539 proposed to remove
the *_storage_size named constants, this paper does not propose
to do so.

Number:

Title: STORAGE_SIZE

Submitted By: J3

Status: For Consideration

References:

Basic Functionality: Add a procedure to ISO_FORTRAN_ENV
                     to return the size in bits of its argument.

Rationale:  There are situations where a program needs to know
            the size of an entity.

Estimated Impact: The impact was estimated by J3 at 167 as Small.

Detailed Specification: A procedure to return the size in bits of its argument.

                        Edits: See paper 04-327 regards possible renumbering
                        of 13.8.2.  These edits assume that paper passes.

                       [125:41+] Add list item

                       "(4+) the intrinsic module function STORAGE_SIZE,"

                       [360:33+++] Add section

                       "13.8.2.2.x STORAGE_SIZE (X [, KIND])

                       *Description.*  Returns the storage size in bits for a
                                       nonpointer nonallocatable scalar
                                       of the declared type of X.

                       *Class.*  Inquiry function.

                       *Arguments.*

                       X               may be of intrinsic or derived type.  It
                                       shall not be polymorphic.  If it is
                                       of derived type, that type shall be
                                       a SEQUENCE or interoperable type and
                                       shall have no allocatable ultimate
                                       components.  If its type has
                                       any deferred type parameters, it shall
                                       be a pointer that is associated or
                                       an allocatable object that is
                                       allocated. It may be a scalar or an array.

                       KIND (optional) shall be a scalar integer initialization
                                       expression.

                       *Result Characteristics.*  Integer scalar.
                                                  If KIND is present, the kind
                                                  type parameter is that
                                                  specified by the value
                                                  of KIND; otherwise, the kind
                                                  type parameter is that
                                                  of default integer type.

                       *Result Value.*  The result value is the size in bits
                                        of the storage unit (16.4.3.1)
                                        in a storage association context
                                        for a nonpointer nonallocatable scalar
                                        with the declared type and
                                        type parameters of X.

                       *Example.*  STORAGE_SIZE(1.0) returns the number of bits
                                   required to store an entity of type default
                                   real.

History: Submitted as 04-121 at 167 and as N1539.