From JLS@liverpool.ac.uk Mon Nov 2 17:03:36 1992 Received: from vm.uni-c.dk by dkuug.dk with SMTP id AA23344 (5.65c8/IDA-1.4.4j for ); Mon, 2 Nov 1992 18:12:33 +0100 Message-Id: <199211021712.AA23344@dkuug.dk> Received: from vm.uni-c.dk by vm.uni-c.dk (IBM VM SMTP V2R2) with BSMTP id 7992; Mon, 02 Nov 92 18:13:59 DNT Received: from UKACRL.BITNET by vm.uni-c.dk (Mailer R2.07) with BSMTP id 9031; Mon, 02 Nov 92 18:13:58 DNT Received: from RL.IB by UKACRL.BITNET (Mailer R2.07) with BSMTP id 3534; Mon, 02 Nov 92 17:14:16 GMT Received: from RL.IB by UK.AC.RL.IB (Mailer R2.07) with BSMTP id 8107; Mon, 02 Nov 92 17:13:53 GMT Via: UK.AC.LIV.IBM; 2 NOV 92 17:12:46 GMT Received: from UK.AC.LIVERPOOL by MAILER(4.4.t); 2 Nov 1992 17:09:41 GMT Date: Mon, 02 Nov 92 17:03:36 GMT From: Lawrie Schonfelder Subject: Re: RFI: Automatic character and ALLOCATABLE, POINTER and TARGET To: jls@juniper.cray.com, SC22/WG5 members In-Reply-To: Your message of Wed, 28 Oct 92 20:38:42 CST X-Charset: ASCII X-Char-Esc: 29 On Wed, 28 Oct 92 20:38:42 CST jls@com.cray.juniper said: >The following is an amended version of a previous posting of 92-206. The >changes are the title, keywords, and addition of questions 3 and 4 which >are related to the original request and have surfaced in Janice Sheperd and >Alan Meyer's recent postings. The amended request will be on the table as >92-206a at the New Haven meeting. > >------- >To : X3J3 X3J3/92-206a >From : Jon Steidel Meeting 123 >Subject: Request for interpretation > > >NUMBER: >TITLE: Automatic character and ALLOCATABLE, POINTER and TARGET attributes >KEYWORDS: Allocatable, automatic, array, character, pointer, target >DEFECT TYPE: Interpretation >STATUS: > >QUESTION: Section 5.1 states: > > The specification-expr (7.1.6.2) of a type-param-value (5.1.1.5) > or an array-spec (5.1.2.4) may be a nonconstant expression provided the > specification expression is in an interface body (12.3.2.1) or in the > specification part of a subprogram. If the data object being declared > depends on the value of such a nonconstant expression and is not a > dummy argument, such an object is called an automatic data object. An > automatic object must not appear in a SAVE or DATA statement nor be declared > with a SAVE attribute nor be initially defined by an = initialization-expr. > >Thus, a character object with a length-selector which is a nonconstant >type-param-value is an automatic object. > >Section 5.1.2.9 states: > > The ALLOCATABLE attribute specifies that objects declared in the statement > are allocatable arrays. Such arrays must be deferred-shape arrays whose > shape is determined when space is allocated for each array by the execution > of an ALLOCATE statement (6.3.1). > >I am unable to find words which prohibit allocatable arrays of automatic >objects. > >Question 1: Is it the intent to allow allocatable arrays of automatic character? My reaction is YES. > > FUNCTION FRED (J) > CHARACTER(LEN=J),DIMENSION(:),ALLOCATABLE :: CH > ALLOCATE (CH(100)) > >Question 2: If allocatable arrays of automatic objects are allowed, is it >correct to assume the array must not have the SAVE attribute? No SAVE must not be specified for all the obvious reasons. > >Question 3: Since objects with the POINTER attribute may be allocated, is >it intended that automatic objects (specifically type character with length >specified by a variable expression) may have the POINTER attribute? YES there is no reason to prohibit them they are simply automatic > >Question 4: The third constraint of Section 7.5.2 states > > The target must be of the same type, type parameters, and rank as the pointer. > >In general, I don't see a problem with allowing the POINTER and TARGET >attribute for automatic arrays. However, there is a problem if TARGET is >intended to be allowed for automatic character, both scalar and arrays, >where the length is specified by a variable expression. Character length >is part of the type and type parameters, but where length is specified by >a variable, the above constraint cannot be diagnosed at compile time. >Was it the intent to allow the TARGET attribute on any automatic objects, >only on automatic arrays except where character length is specified by >a variable expression, or for no automatic objects? If the intent is to >allow TARGET on all automatic objects, the above constraint must be relaxed >as it cannot be detected at compile time. If this requires a constraint to be recast as a semantic restriction so be it. pointer assignment should obey this rule. > > >ANSWER: > >Discussion: > >REFERENCES: > >EDIT: > >SUBMITTED BY: Jon Steidel >HISTORY: Initially drafted as X3J3/92-206 >