From lrajchel@ANSI.org Mon Dec 18 17:10:22 2000 Received: from ratatosk.DK.net (ratatosk.DK.net [193.88.44.22]) by dkuug.dk (8.9.2/8.9.2) with ESMTP id RAA51996; Mon, 18 Dec 2000 17:10:02 +0100 (CET) (envelope-from lrajchel@ANSI.org) Received: from email1.ansi.org (mail.ansi.org [165.254.114.6]) by ratatosk.DK.net (8.9.3+Sun/8.9.1) with ESMTP id RAA08229; Mon, 18 Dec 2000 17:10:00 +0100 (MET) Received: by email1.ansi.org with Internet Mail Service (5.5.2650.21) id ; Mon, 18 Dec 2000 11:08:32 -0500 Message-ID: <2F81C8110D55D411882A0020356797B21519D7@email1.ansi.org> From: Lisa Rajchel To: "'sc22info@dkuug.dk'" Cc: "'Simonsen, Keld'" Subject: SC 22 N 31942 Date: Mon, 18 Dec 2000 11:08:31 -0500 X-Mailer: Internet Mail Service (5.5.2650.21) Dear Members, It has been pointed out that the previously circulated version of SC 22 N 31942 is incorrect. It appears that in my attempt to group the related documents together I converted the text file to a word document and the conversion from text to Word corrupted various elements in the document. I apologize for the problems this created. Please discard the previously circulated Word version of SC 22 N 31942 and replace it with the attached document. ____________________________________________________________________________ _______________ ISO/IEC JTC 1 N 31942 ISO/IEC JTC1/SC22/WG5-1422 Defect reports that led to corrigendum 1 and responses to them Stan Whitlock, 8 November 2000 ---------------------------------------------------------------------- NUMBER: 000001 TITLE: Visibility of a data object with statement scope KEYWORDS: visibility, data object, statement scope, scope DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: Part 1: Consider the following program: MODULE mod INTEGER, PARAMETER :: jmin(1:10) = (/ (i, i = 1, 10) /) END MODULE PROGRAM main USE mod INTEGER :: i DO i = 1, 10 PRINT *, 'jmin(i) = ', jmin(i) END DO END PROGRAM Some Fortran compilers consider the implied-DO variable I used in the module to be visible to program units using the module and some Fortran compilers do not consider the I to be visible to using program units. Is an entity with statement scope in the specification part of a module visible to a program unit using the module and accessing the public data of the module as exemplified by the above example? Part 2: Consider the adaptation of the example program from Part 1: MODULE mod INTEGER, PARAMETER :: jmin(1:10) = (/ (i, i = 1, 10) /) CONTAINS SUBROUTINE one i = 99 ! Is this a local or module variable? ! Compilers that export I probably say module END SUBROUTINE SUBROUTINE two PRINT *, i END SUBROUTINE END MODULE The module specification part uses the variable I as an implied-DO variable of an array constructor. Module procedure ONE sets a variable named I to a value. Given: * An implicitly declared data object in the module specification part where the variable has statement scope, and * An implicitly declared variable in a module procedure where the variable has the same name as the variable described in the first bullet of this list is the variable in the module procedure a module variable (known to the entire module and thus available outside the module) or is the variable local to the module procedure? ANSWER: The implied-DO variable is not visible to the using program. 14.1.3 Statement Entities states, in part, that The name of a variable that appears as the DO variable of an implied-DO in a DATA statement or an array constructor has a scope of the implied-DO list. It has the type and type parameter that it would have if it were the name of a variable in the scoping unit that includes the DATA statement or array constructor and this type must be integer. The words "would have if it were" were intended to convey the idea that the existence of an array constructor or data implied-DO variable does not actually cause an associated variable in the scoping unit to come into existence. Also, the following text appears in the same section (281:12-14): If the name of a global or local entity accessible in the scoping unit of a statement is the same as the name of a statement entity in that statement, the name is interpreted within the scope of the statement entity as that of the statement entity. The word "If" here implies that there need not be any such global or local entity with the same name as that of the statement entity. The first edit makes this clear. The second edit makes the same point for FORALL statements and constructs. EDITS: Page 280, Clause 14.1.3, at the end of the first paragragh (280:44) add: The appearance of a name as the DO variable of an implied-DO in a DATA statement or an array constructor is not an implicit declaration of a variable whose scope is the scoping unit that contains the statement. Page 281, Clause 14.1.3, at the end of the second paragraph [281:4] add: The appearance of a name as an index-name in a FORALL statement or FORALL construct is not an implicit declaration of a variable whose scope is the scoping unit that contains the statement or construct. SUBMITTED BY: Larry Rolison HISTORY: 97-237 m143 submitted 00-158 m153 passed unanimously 00-254 m154 passed J3 letter ballot #2 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000003 TITLE: Ability to overload the character operator // KEYWORDS: overload, intrinsic, // DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: On page 89 of the Fortran 95 standard, the Note at the bottom of Table 7.1 states in part: For the intrinsic operators REQUIRING {emphasis not in standard} operands of type character, the kind type parameters of the operands shall be the same. Since there is only one intrinsic operator (//) that REQUIRES its operands to be of type character, one may conclude that the operands of the // operator MUST be of type character and MUST have the same kind type parameters. The last sentence of the first full paragraph on page 90 restates the above rule for intrinsic uses of // as follows: For the character intrinsic operator //, the kind type parameters shall be the same. Contrast this with the last sentence of the last paragraph of this section: A {character relational intrinsic operation} is a relational intrinsic operation where the operands are of type character and have the same kind type parameter value. >From the wording of this last sentence, one may conclude that if the kind type parameters are the same, then the relational operation is intrinsic but if the kind type parameters are NOT the same, then the relational operation is NOT intrinsic and must be defined via a user-provided function. Thus, it is possible for the character operands of a relational operator to have differing kind type parameter values. Now compare this to the following sentence from 7.1.4.2: For an expression // where and are of type character, the character length parameter is the sum of the lengths of the operands and the kind type parameter is the kind type parameter of , which shall be the same as the kind type parameter of . Note that there is no text or title to indicate that the description is only for intrinsic operators. There appears to be no way to overload the // symbol at all since the wording does not restrict the rule to the intrinsic interpretation of the operator (it appears in fact from the wording that once the operands are of type character, there can be no other interpretation other than intrinsic). This is surely not what was intended. The wording should be redone to more closely resemble that for the character relational operators such that if the operands of // do not have the same kind type parameters, an overload is allowed (and the operator is not interpreted as being intrinsic). (See also 7.2.2 Character intrinsic operation.) ANSWER: Intrinsic concatenation is defined only for character operands with the same kind type parameter value. This is stated clearly (90: 8-9): 'For the character intrinsic operator //, the kind type parameters shall be the same'. There is a need for a similar restriction at this point for relational intrinsic operators with character operands. The words at the end of the next paragraph (90: 12) actually suggest that there are relational intrinsic operations for character operands of different kind type parameter values that are not character relational intrinsic operations. The word 'requiring' in the last sentence in the note in Table 7.1 should be changed since all the intrinsic operators with character operands require their operands to have the same kind type parameter value. EDITS: Page 89, Table 7.1, penultimate line (89:38). Change 'requiring' to 'with'. Page 90, line 9. Add 'For the relational intrinsic operators with character operands, the kind type parameters shall be the same'. Page 90, line 12. Delete 'and have the same kind type parameter value'. SUBMITTED BY: Larry Rolison HISTORY: 97-239 m143 submitted 00-159 m153 passed unanimously 00-254 m154 passed J3 letter ballot #2 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000005 TITLE: Value returned by SELECTED_REAL_KIND KEYWORDS: SELECTED_REAL_KIND DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: The SELECTED_REAL_KIND intrinsic function does not appear to cover one specific case for real data types. Consider the following precisions and ranges for a particular model: KIND TYPE PRECISION RANGE 4 6 37 8 15 307 16 31 291 A test case for a system with this model is: PRINT *, 'selrealkind(31,291) = ', SELECTED_REAL_KIND(P1,R)1) PRINT *, 'selrealkind(31,292) = ', SELECTED_REAL_KIND(P1,R)2) PRINT *, 'selrealkind(32,291) = ', SELECTED_REAL_KIND(P2,R)1) PRINT *, 'selrealkind(32,292) = ', SELECTED_REAL_KIND(P2,R)2) END The Result Value section of the description of SELECTED_REAL_KIND clearly describes the result value when the values of P and R are within the ranges specified for the given implementation of the real data type model. It further describes the values to be returned by SELECTED_REAL_KIND when a value of P or R is not within the range of model numbers specified by the implementation. From the text in the Result Value section, the following may be determined: * The reference to SELECTED_REAL_KIND(P1,R)1) (first PRINT line) should return the (kind type parameter) value 16. * The third and fourth SELECTED_REAL_KIND references should return -1 since the PRECISION argument is outside the set of allowed precision values. However, the value returned by the second reference to SELECTED_REAL_KIND is unknown since it does not appear to be covered by the wording of the Result Value paragraph of section 13.14.95. 1. What should the processor return for the value of the SELECTED_REAL_KIND intrinsic function when it does not have a single data type that satisfies both the P and R values? 2. In particular, given the precision and range values shown above, what should the processor return for the last three invocations of the SELECTED_REAL_KIND intrinsic function? ANSWER: The intention is that the value -1 be returned if the range can be supported but the precision cannot, the value -2 be returned if the precision can be supported but the range cannot, and the value -3 be returned if neither the precision nor the range can be supported. Provision needs to be made for the case where each can be supported, but not in combination. With the edit below, the returned values for the four invocations will be 16, -4, -1, -1. In addition, using the model above, these test cases: PRINT *, 'selrealkind(32) = ', SELECTED_REAL_KIND(P2) PRINT *, 'selrealkind(r08) = ', SELECTED_REAL_KIND(R08) the returned values for the two invocations will be -1, -2. EDITS: Page 266, Clause 13.14.95, line 8 (266: 23). After , add 'If P or R is absent, the result value is as would have been obtained with the argument present with the value 0.' Page 266, Clause 13.14.95, lines 11-14 (266: 26-29). Replace 'the result is -1 ... is supported.' by 'the result is -1 if the processor does not support a real data type with a precision greater than or equal to P but does support a real data type with an exponent range greater than or equal to R, -2 if the processor does not support a real data type with an exponent range greater than or equal to R but does support a real data type with a precision greater than or equal to P, -3 if the processor supports no real data type with either of these properties, and -4 if the processor supports real data types for each separately but not together.' SUBMITTED BY: Larry Rolison / Joanne Brixius HISTORY: 97-241 m143 submitted 00-161 m153 passed unanimously as amended 00-254 m153 passed by J3 letter ballot as amended 00-Aug Oulu passed by WG5 as amended in N1399 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000069 TITLE: What is a numeric character? KEYWORDS: list-directed input DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete Section 10.8.1 of the Fortran 95 standard states If the next effective item is of type default character and ... (4) The leading characters are not numeric followed by an asterisk, ... The standard does not define what a numeric character is. QUESTION: What is a numeric character? ANSWER: A numeric character is a . REFERENCES: ISO/IEC 1539-1:1997(E), Section 10.8.1 EDITS: Section 10.8.1, list item (4), [176:17], replace the text (4) The leading characters are not numeric followed by an asterisk with (4) The leading characters are not s followed by an asterisk SUBMITTED BY: Robert Corbett HISTORY: 99-191 m150 Submitted by Robert Corbett 99-214 m150 J3 draft response, approved uc 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000070 TITLE: Asymmetry between constant specification and initialization expressions KEYWORDS: Initialization expressions; specification expressions DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: Consider the following programs. PROGRAM P1 REAL :: B = 4.0*ATAN(1.0) PRINT *, B END PROGRAM P1 PROGRAM P2 INTEGER :: A(INT(4*ATAN(1.0))) = 17 PRINT *, A END PROGRAM P2 According to 7.1.6.1 program unit P1 is not standard-conforming because of the reference to the intrinsic function ATAN which is not permitted in an initialization expression. According to 7.1.6.2 program unit P2 is standard-conforming; the reference to the intrinsic function ATAN is allowed by item (8) in the definition of a restricted expression. Expressions in the array bounds of an initialized entity are only required to be constant specification expressions, not initialization expressions. Was it the committee's intent to permit ATAN to appear in the array bounds of an initialized entity but not in the initialization value? ANSWER: No, this was not the intent. These expressions should have been described as initialization expressions instead of as constant expressions. This error also occurs for the definitions of an automatic entity, common block definitions and component definitions. The edits below change all of these to require initialization expressions instead of constant expressions. EDIT: [39:15-16] Change "a constant specification expression (7.1.6.2)" to "an initialization expression (7.1.6.1)". [39:23-24] Change "a constant specification expression (7.1.6.2)" to "an initialization expression (7.1.6.1)". [40:30] Change "a constant" to "an initialization". {Fix note.} [48:47-48] Change "may be a nonconstant expression provided the specification expression" to "shall be an initialization expression unless it". [49:1-3] Delete "If a ... nonconstant expression." [49:4-5] Change "such a nonconstant expression" to "a that is not an initialization expression". {Fix definition of "automatic object".} [49:9] Change "a nonconstant expression" to "an expression that is not an initialization expression". {Fix evaluation time for character length.} [51:33] Change "a constant specification" to "an initialization". {Fix statement function character lengths.} [54:29-30] Change "nonconstant expressions" to "expressions that are not initialization expressions". [54:33] Change "nonconstant specification" to "not initialization". {Fix automatic array definition.} [54:34] Change "nonconstant specification" to "not initialization". {Fix evaluation time for explicit-shape array bounds.} [54:36-37] Replace sentence with "The bounds of such an array are unaffected by the redefinition or undefinition of any variable during execution of the procedure.". [56:32] Change "nonconstant specification" to "not initialization". {Fix evaluation time for assumed-size array bounds.} [56:33-34] Replace sentence with "The bounds of such an array are unaffected by the redefinition or undefinition of any variable during execution of the procedure.". [69:3-4] Change "a constant specification expression (7.1.6.2)" to "an initialization expression (7.1.6.1)". {Fix common block array-specs.} [192:26] Change "a constant" to "an initialization". {Fix characteristics of function results.} SUBMITTED BY: Henry Zongaro HISTORY: 99-178 m150 submitted 99-216r1 m150 approved uc 00-133 m152 additional edit, approved uc 00-208 m153 Passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 as amended {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000072 TITLE: Resolving generic procedure references KEYWORDS: generic, ELEMENTAL DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: Consider INTERFACE generic ELEMENTAL SUBROUTINE sub_e(a) REAL,INTENT(INOUT) :: a END SUBROUTINE sub_3(a) REAL,INTENT(INOUT) :: a(:,:,:) END END INTERFACE This is legal (it obeys the restrictions in 14.1.2.3). This allows the ambiguous reference REAL x(10,20,30) CALL generic(x) However, the existing text in 14.1.2.4.1 does not explain which procedure is called, because the reference is consistent with two procedures. Note 14.6 indicates that the intent is to call the nonelemental procedure in this case. Is note 14.6 correct as to the intent of the standard? ANSWER: Yes, note 14.6 is correct; an edit is supplied to the resolution rules to implement this. EDIT: [278:41] After "with" insert "a non-elemental reference to". SUBMITTED BY: Malcolm Cohen HISTORY: 99-218 m150 submitted, approved uc 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000076 TITLE: INTENT(IN) dummy arguments and implied DO loops KEYWORDS: INTENT(IN), implied DO DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: The Fortran 95 standard [53:13-17] says "Constraint: A dummy argument with the INTENT(IN) attribute ... shall not appear as ... (3) A DO variable or implied-DO variable, ..." The apparent intent is to prevent any modification of the dummy argument; however, use in data-implied-do and array-constructor-implied-do would not modify the dummy argument. Is the constraint intentionally stronger than necessary? ANSWER: The constraint is only intended to apply to implied-DO variables in I/O lists. The following edit makes this clearer. EDIT: [53:17] Change "A DO variable or implied-DO variable" to "A in a or ". SUBMITTED BY: Malcolm Cohen HISTORY: 99-199 m150 submitted 99-199r1 m150 approved uc 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000077 TITLE: INTENT(IN) dummy arguments and NULLIFY KEYWORDS: INTENT(IN), NULLIFY DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: The Fortran 95 standard [53:13-17] says "Constraint: A dummy argument with the INTENT(IN) attribute, or a subobject of such a dummy argument, shall not appear as ... (2) The of a , ..." Consider: TYPE t REAL,POINTER :: value END TYPE ... SUBROUTINE s(x) TYPE(t),INTENT(IN) :: x IF (.FALSE.) x%value => NULL() ! (1) IF (.FALSE.) NULLIFY(x%value) ! (2) According to the constraint above, line (1) is illegal. However, there is no corresponding constraint for the NULLIFY statement, implying that line (2) is legal. Should subobjects of INTENT(IN) dummies also be constrained against appearing as the of a NULLIFY statement? ANSWER: Yes, there should be a constraint disallowing INTENT(IN) dummy arguments in a NULLIFY statement. The edit below corrects this omission. EDIT: [53:16] Replace constraint (2) with "A in a or , " SUBMITTED BY: Malcolm Cohen HISTORY: 99-200 m150 submitted 99-200r1 m150 approved uc 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 as amended {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000079 TITLE: Pointer Assignment and Allocatable Arrays KEYWORDS: Pointer assignment, allocatable DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete Consider PROGRAM p REAL,ALLOCATABLE,TARGET :: x(:) POINTER p(:) p => x ALLOCATE(x(10)) PRINT *,SIZE(p) END This appears to be a legal program - there seems to be no prohibition against pointer assignment to an unallocated allocatable array and allocating the array does not seem to alter the association status of any pointer associated with an allocatable array. Should there be a prohibition against pointer assignment to an unallocated allocatable array? ANSWER: Yes; an edit is supplied to correct this oversight. EDIT: In clause 7.5.2, at the end of the paragraph that begins "The shall" [111:8+], insert: "If the is an allocatable array, it shall be currently allocated." SUBMITTED BY: Malcolm Cohen HISTORY: 99-223 m150 submitted, approved 6-4 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000080 TITLE: Host association and the EXTERNAL attribute KEYWORDS: Host association, EXTERNAL DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: Use of a (non-intrinsic) name as a procedure in a procedure reference implicitly confers the EXTERNAL attribute on the name. Does this happen when the name is host-associated? For example, f90 interp 143 established that MODULE m1 REAL x CONTAINS SUBROUTINE s PRINT *,x(1) END SUBROUTINE END was invalid - 11.3.2 now says that a "procedure with implicit interface and public accessibility shall explicitly be given the EXTERNAL attribute in the scoping unit of the module". However, this text says nothing about private entities, so considering: MODULE m2 REAL,PRIVATE :: x CONTAINS SUBROUTINE s PRINT *,x(1) END SUBROUTINE END This example does not violate 11.3.2 because X is PRIVATE. Is this example conforming? Further, considering: PROGRAM m3 REAL x CONTAINS SUBROUTINE s PRINT *,x(1) END SUBROUTINE END This example is not of a module and so 11.3.2 does not apply. Is this example conforming? Further, considering PROGRAM m4 EXTERNAL x CONTAINS SUBROUTINE s PRINT *,x(1) END SUBROUTINE END Does the invocation as a function in an internal procedure cause X to be implicitly typed, or is this not conforming? ANSWER: No, use of a host-associated name never confers attributes on the host entity. Examples M2, M3, and M4 are therefore invalid. Edits are supplied. EDIT: [188:28] Delete "and public accessibility". [188:31] Delete "with public accessibility". [283:16+] Add new paragraph after the note "An external or dummy procedure with an implicit interface that is accessed via host association shall explicitly be given the EXTERNAL attribute in the host scoping unit or be used as a procedure in that scoping unit; if it is invoked as a function in the inner scoping unit, its type and type parameters shall be explicitly declared in a type declaration statement in the host scoping unit or it shall be used as a procedure in the host scoping unit. An intrinsic procedure that is accessed via host association shall explicitly be given the INTRINSIC attribute in the host scoping unit or be used as an intrinsic procedure in that scoping unit." SUBMITTED BY: Malcolm Cohen HISTORY: 99-230 m151 submitted 99-230r1 m151 approved uc 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 amended as requested in corrigendum #1 ballot {N1420} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000082 TITLE: Usage of BOZ literal constants KEYWORDS: BOZ constant DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: Consider: INTEGER X(10) DATA X(B"001")/42/ END This is apparently conforming, since the constraint at [32:15] says "A may appear only in a DATA statement." But this rules out X(B"001") = 42 Is this an error? ANSWER: Yes, BOZ literal constants should be restricted to being a . EDITS: [32:15] Replace text of constraint with "A may appear only as a in a DATA statement." SUBMITTED BY: Malcolm Cohen HISTORY: 99-275 m151 submitted 99-275r1 m151 approved uc 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000083 TITLE: Scope of array-constructor implied-DO variable KEYWORDS: Scope, implied DO, array constructor DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: 14.1.3 states that the scope of an implied-DO variable in an array constructor is "the implied-DO list". There is no such syntax term: what is meant? In particular, in the array constructor (/ (I,I=1,I) /) are all three I's references to the implied-DO variable, or is one of them a reference to a variable I in the enclosing scoping unit? ANSWER: All occurences of I within the implied-DO are references to the implied-DO variable, none of them can reference a variable in the enclosing scoping unit. The term "implied-DO list" is confusing in this context; "implied-DO" was intended. An edit is supplied for clarification. DISCUSSION: The term "implied-DO list" is used in several places where the context is that of the values produced by the implied-DO. This is an inappropriate term to use for specifying scope. Also, the second and third occurrences of "I" in the example shown are part of the syntax item . It would be unreasonable to read "implied-DO list" as meaning (for array constructors) " and the in but not the s in ." Note that the problem does not arise for because variables other than implied-DO variables are not permitted in the limit expressions. With this interpretation the example array constructor supplied is not valid Fortran, as it is not permissible to reference the value of an variable in one of its limit expressions. EDITS: [280:41] Replace "implied-DO list" with "implied-DO". SUBMITTED BY: Malcolm Cohen HISTORY: 00-124 m152 Submitted 00-124r1 m152 approved uc 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: 000084 TITLE: Events that cause variables to be defined KEYWORDS: Definition status, INTENT(OUT) DEFECT TYPE: Erratum STATUS: Included in corrigendum/complete QUESTION: Item (6) of 14.7.5 says "A reference to a procedure causes the entire dummy argument to become defined if the entire corresponding actual argument is defined with a value that is not a statement label. A reference to a procedure causes a subobject of a dummy argument to become defined if the corresponding subobject of the corresponding actual argument is defined." For an INTENT(OUT) dummy this appears to conflict with 14.7.6 item (13)(b) "When a procedure is invoked ... (b) A dummy argument with INTENT(OUT) is undefined except for any nonpointer direct components of the argument for which default initialization is specified." So in X = 3 CALL S(X) ... SUBROUTINE S(A) INTENT(OUT) A ... Is A defined (with the value 3) in accordance with 14.7.5, or undefined in accordance with 14.7.6? Similarly, for subobjects of INTENT(OUT) dummies, does 14.7.5 take precedence or 14.7.6? ANSWER: A is undefined in accordance with 14.7.6. An edit is supplied to remove the conflict. Similarly, 14.7.6 takes precedence for subobjects. EDITS: [289:9] Before "entire" insert "dummy argument does not have INTENT(OUT) and the". [289:12] Before "corresponding" insert "dummy argument does not have INTENT(OUT) and the". SUBMITTED BY: Malcolm Cohen HISTORY: 00-141 m152 submitted, approved uc 00-209 m153 passed by J3 letter ballot #1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 edits contained in corrigendum #1 {N1421} ---------------------------------------------------------------------- NUMBER: F90/000100 TITLE: ASSOCIATED intrinsic and zero-sized objects KEYWORDS: ASSOCIATED intrinsic, zero-sized objects, target, pointer DEFECT TYPE: Interpretation STATUS: Complete QUESTION: What is the behavior of the ASSOCIATED intrinsic function for zero-sized arguments? Question 1: Can the single argument form of the ASSOCIATED intrinsic return true as its result if the argument's target is zero sized? Question 2: Can the two-argument form of the ASSOCIATED intrinsic return true when both arguments are zero sized? The following need answers only if the answer to question 2 is yes. Question 2a: If the arguments to ASSOCIATED are zero sized but of rank greater than one, must the extents of each dimension be the same for ASSOCIATED to return true? For example, what is printed by the following program? PROGRAM HUH REAL, DIMENSION(:,:), POINTER :: P1, P2 REAL, DIMENSION(10, 10), TARGET :: A P1 => A(10:9:1, :) P2 => A(:, 10:9:1) PRINT *, ASSOCIATED (P1, P2) END Question 2b: In the following example, rank, shape, type, kind type parameters, and extent of dimensions of the zero-sized arguments to ASSOCIATED match, but the second argument is not the same as the right hand side of the previous pointer assignment statement. What is the output of this program? (Does a notion of "base address" come to play for zero-sized objects as it does for nonzero-sized objects?) PROGRAM HMMM REAL, DIMENSION(:,:), POINTER :: P1 REAL, DIMENSION(10, 10), TARGET :: A P1 => A(:, 2:1:1) PRINT *, ASSOCIATED (P1, A(:, 3:2:1)) END ANSWERS: Answer 1: The one-argument form of ASSOCIATED returns a result of true if the pointer actual argument is currently associated with a target, even if the target is zero sized. Answer 2: No; if either argument is zero sized the result is false. The edits in defect item 000027 clarify the intent. Answer 2a: The result is false because P1 and P2 each are zero sized. Answer 2b: The result is false because the arrays are of zero size. Discussion: The reasons for having the ASSOCIATED function return false for zero-sized arrays is based on an analogy with sharing storage and how assignment works. In normal English we understand the concept of "totally associated" and "partially associated". If two things are totally associated then doing something to one of them does the exact same thing to the other. If two things are partially associated then doing something to one of them does something to the other. Section 14.6.3.3 hints at this by discussing "totally associated" in terms of "the same storage sequence". After executing assignment statements like I = values J = different_values we would call I and J associated if it were no longer true that I is equal to values. Zero-sized arrays are the end case where doing "something" to them is equivalent to doing nothing to them. And in the example above we would still have I is equal to values after the assignment if both I and J were zero-sized but would otherwise appear to be associated. We could also conclude that after the pair of assignment statements above executed we would have I is equal to different_values if I and J were zero sized, since the comparison operators return true for zero-sized objects. However, on balance it seems better to view the comparison with the initial conditions, not the potential changed conditions. As a practical matter, sensible use of the ASSOCIATED function with zero-sized arrays will usually require user special casing of the results. EDITS: None. SUBMITTED BY: Jon Steidel - X3J3/92-240 HISTORY: ui 114 (jw note) 92-240 m123 Submitted 93-035 m124 response, adopted by unanimous consent 93-111 m125 ballot, return to subgroup based on Hirchert, Maine comments. Also see Ellis comment for 000108 93-138r m125 revised response adopted 11-8. 93-255r1 m127 ballot passed 21-3 94-160 m129 WG5 ballot, failed 94-253r3 m130 revised response, approved u.c. 94-306 m131 X3J3 ballot, approved 15-4 95-044 m132 WG5 ballot, approved, with Reid edit 95-306r1 m135 withdrew edits as defect item 27 supplies better edits, approved u.c. 96- m136 X3J3 ballot, approved 15-1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 no edits for corrigendum #1 => processing complete ---------------------------------------------------------------------- NUMBER: F90/000179 TITLE: DO variable with POINTER attribute KEYWORDS: DO variable, POINTER attribute DEFECT TYPE: Interpretation STATUS: Complete QUESTION: The first constraint following rule R822 states: "Constraint: The must be a named scalar variable of type integer, default real, or double precision real." The definition of loop initiation (8.1.4.4.1) states: "(2) The DO variable becomes defined with the value of the initial parameter 1." The definition of the execution cycle of a DO loop (8.1.4.4.2) states: "(3) ... The DO variable, if any, is incremented by the value of the incrementation parameter 3." Consider the following program: INTEGER, POINTER :: PTR INTEGER, TARGET :: LCV PTR => LCV DO PTR = 1, 3 PRINT *, LCV END DO END Note that the DO variable has the POINTER attribute. The POINTER attribute does not seem to be prohibited for the DO variable, but when the DO variable has the POINTER attribute, it is unclear as to whether the DO variable is the pointer or the target of the pointer. That is, it is unclear as to whether the pointer or the target is to be "defined" (8.1.4.4.1) or incremented (8.1.4.4.2). Also consider the following modification of the above program: INTEGER, POINTER :: PTR INTEGER, TARGET :: LCV1, LCV2 LCV1 = 1 LCV2 = 4 PTR => LCV1 DO PTR = 1, 3 IF (...) PTR => LCV2 ! An alternate EXIT form? END DO END The standard does not seem to address what happens when the DO variable is switched to a different variable while the loop is active. Is it the intent of the standard to permit a DO variable with the POINTER attribute? ANSWER: Yes, a DO variable may have the POINTER attribute. Discussion: There are a number of contexts in the language where the target of a pointer is referenced or defined when it is the pointer name that appears. Two of these are cited in items (2) and (3) in the Question. In (2), the target of the pointer variable is defined with the value of the DO loop initial value parameter. In (3), the target of the pointer variable is incremented. Other examples of these kinds of contexts are: * Section 6.3.1, which describes the ALLOCATE statement: "If the STAT= specifier is present, successful execution of the ALLOCATE statement causes the to become defined with a value of zero." * Section 9.4.1.5, which describes the semantics of the I/O error branch: "(2) If the input/output statement also contains an IOSTAT= specifier, the variable specified becomes defined with a processor-dependent positive integer value," In contexts such as these, the variable involved may have the POINTER attribute and it is the intent of the standard that it is the target of the pointer that is being defined, incremented, etc. With respect to the modified example in the Question, the standard does address what happens when the DO variable appears on the left hand side of a pointer assignment. In the modified example in the Question, the statement IF (...) PRT => LCV2 ! An alternate EXIT form? is prohibited. Section 14.7.6 states: "(18) Execution of a pointer assignment statement that associates a pointer with a target that is defined causes the pointer to become defined." but section 8.1.4.4.2 states: "Except for the incrementation of the DO variable that occurs [when the DO variable is incremented by the value of the incrementation parameter], the DO variable must neither be redefined nor become undefined while the DO construct is active." Thus, since the pointer assignment statement causes the DO variable to become (re)defined, it is prohibited. Similarly, if the modified example had contained within the DO construct an assignment statement such as: PRT = 10 such an assignment statement would also be prohibited because defining the target of a pointer also defines the pointer as stated in section 14.6.2.2: "The definition status of a pointer is that of its target." EDITS: None. SUBMITTED BY: Larry Rolison HISTORY: 94-226r1 m130 submitted, approved 10-1 94-306 m131 X3J3 ballot approved 19-0 95-044 m132 WG5 ballot, failed see Cohen's comments 95-246 m134 revised edits, approved u.c. 95-256 m135 X3J3 ballot, failed 10-6 95-304r1 m135 revised response, delete edits, approved u.c. 96- m136 X3J3 ballot, approved 15-1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 no edits for corrigendum #1 => processing complete ---------------------------------------------------------------------- NUMBER: F90/000185 TITLE: What is the allocation status of an array after an allocation failure? KEYWORDS: ALLOCATE, POINTER, DEALLOCATE, status DEFECT TYPE: Interpretation STATUS: Cpmplete QUESTION: It does not appear that the standard defines the allocation status of an array if an ALLOCATE statement fails and returns a nonzero STAT= value? Given a program segment such as: REAL, ALLOCATABLE, DIMENSION(:) :: A,B,C ALLOCATE(A(10), B(10), C(10), STAT = ISTAT) Question 1: If "ISTAT" comes back non-zero, is it legal to deallocate the arrays and try to reallocate them with smaller sizes? Question 2: If instead of allocatable arrays, the variables had been pointers, is it legal to NULLIFY them? Question 3: Are the answers to questions 1 and 2 different if a single array is allocated rather than a list? Question 4: If a DEALLOCATE fails for a list, what is the allocation status of the arrays? Question 5: Is it acceptable to use the ALLOCATED and/or ASSOCIATED functions to attempt to recover from a failure? Question 6: 6.3.1.1 might be read to mean that successful allocation makes the arrays "currently allocated" and otherwise leaves them "not currently allocated". But that's not an obvious reading of the text. In some ways I/O is similar to allocate (they both process a list of things and have a STAT= clause). If an input statement fails then everything in the list becomes undefined. Does that apply by analogy to ALLOCATE? ANSWER 1: Yes. Note that one or more of the arrays is expected to have an allocation status of "currently not allocated", due to the error which occurred. See the Discussion below. Note that this example only used allocatable arrays. If a pointer appears in a DEALLOCATE statement, its pointer association status must be defined (section 6.3.3.2). See the Discussion below. ANSWER 2: Yes. See section 14.6.2.3. ANSWER 3: No, the answers are the same. See Answer 6 below. ANSWER 4: When a DEALLOCATE with a "STAT=" specifier fails, those arrays that were successfully deallocated will have an allocation status of deallocated. Those arrays not successfully deallocated retain their previous allocation status. ANSWER 5: For ALLOCATED, yes. For ASSOCIATED, it depends on the pointer association status of the pointer at the time the ASSOCIATED intrinsic is called. The ALLOCATED intrinsic may be called with any allocatable array whose allocation status is either currently allocated or currently not allocated. The ASSOCIATED intrinsic must not be called with a pointer whose pointer association status is undefined (section 6.3.3.2). See the Discussion below. ANSWER 6: No. The standard does not require a processor to allocate the variables specified in an ALLOCATE statement as a group; therefore, a processor may successfully allocate some of the arrays specified in an ALLOCATE statement even when that ALLOCATE statement assigned a positive value to the variable specified in the STAT= specifier. Discussion: Only when the allocation status of an array is undefined is it illegal to specify the array in a DEALLOCATE statement. The only way for an allocatable array to have a status of undefined is described in section 14.8, item (3). If an array specified in a DEALLOCATE statement has an allocation status of not currently allocated when the DEALLOCATE statement is executed, an error condition occurs as described in section 6.3.3.1. The behavior of the DEALLOCATE statement in the presence of an error condition is described in section 6.3.3. Immediately after the execution of an ALLOCATE statement, all allocatable arrays specified in that ALLOCATE statement will have a defined allocation status. The arrays that were successfully allocated will have an allocation status of allocated, while any arrays not successfully allocated will retain their previous allocation status. When a pointer is specified in an ALLOCATE statement which fails (assigns a positive value to ISTAT in this example), then the pointer association status of that pointer will not be changed if the allocation failed for that particular pointer. If that pointer previously had a pointer association status of undefined, it will still have a pointer association status of undefined immediately after the ALLOCATE statement is executed; therefore, it would be illegal to specify that pointer in a DEALLOCATE statement (section 6.3.3.2) or in a call to the ASSOCIATED intrinsic (section 13.13.13), unless the allocation status of the pointer was first changed to be defined (either associated or disassociated). EDITS: None. SUBMITTED BY: Dick Hendrickson HISTORY: 94-296 m131 submitted 95-039 m132 draft response, approved u.c. 95-101 m133 X3J3 ballot approved, 12-6 95-310r1 m135 revised response to be consistent with F95, approved u.c. 96- m136 X3J3 ballot approved, 15-1 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 no edits for corrigendum #1 => processing complete ---------------------------------------------------------------------- NUMBER: F90/000194 TITLE: Statements between SELECT CASE and CASE KEYWORDS: FORMAT statement, DATA statement, SELECT CASE statement, CASE statement, INCLUDE line, statement order DEFECT TYPE: Interpretation STATUS: Complete QUESTION: 1. Figure 2.1 (page 11) shows that FORMAT and DATA statements may be intermixed with executable constructs but it is not clear at what points within an executable construct these statements may appear. In particular, may FORMAT and DATA statements appear between the SELECT CASE statement and the first CASE statement of a CASE construct? 2. May an INCLUDE line appear between the SELECT CASE statement and the first CASE statement of a CASE construct? ANSWER: 1. No. In general, FORMAT and DATA statements may appear in the IF, CASE and DO executable constructs because these constructs contain blocks and a block is defined in section 8.1 (on page 95) to consist of s, which in turn are defined as being made up of FORMAT and DATA statements, among others. However, the syntax rules for the CASE construct do not provide for any blocks or any other statements to appear between the SELECT CASE statement and the first CASE statement of a CASE construct. The sentence in 8.1 [95:12] that defines a block in prose introduces the general concept of a block, and does not precisely define the BNF term. The BNF syntax rules give the precise definition. 2. Yes. An INCLUDE line may appear between a SELECT CASE statement and the first CASE statement of a CASE construct because an INCLUDE line is a line, not a statement. EDITS: None. SUBMITTED BY: Larry Rolison HISTORY: 94-383r1 m131 submitted with proposed response, approved 13-3 95-034r1 m132 X3J3 ballot approved 19-1, with edits 95-116 m133 (N1112) correct typo in answer 2. 95-305r1 m135 changed to match F95 approved edits, approved u.c. 96- m136 X3J3 ballot approved 16-0 00-Aug Oulu passed by WG5 {N1403} 00-Oct wg5 no edits for corrigendum #1 => processing complete ----------------------------------------------------------------------