J3/14-193
To:        J3
From:      Van Snyder
Subject:   Interp concerning interdependence of specifier values
Date: 2014 June 18
Reference: Interp F03/0096 (revised for F2008 in 11-129 and Corr. 2)

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NUMBER: TBD
TITLE: Interdependence of specifier values in input/output statements
KEYWORD: specifier, input/output statement
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTIONS:

1. Are the following INQUIRE statement permitted?

    LOGICAL :: Exist, Opened
    INQUIRE ( FILE='fred', EXIST=exist )
    INQUIRE ( UNIT=42, OPENED=opened

2. Is the following INQUIRE statement permitted?

    INTEGER :: U
    INTERFACE
      FUNCTION P ( A )
        INTEGER, INTENT(IN) :: A
        INTEGER, POINTER :: P
      END FUNCTION P
    END INTERFACE
    INQUIRE ( FILE='fred', NUMBER=u, POSITION=p(u) )

3. Is the following READ statement permitted?

    INTEGER :: STATS(42)
    NAMELIST /IN/ V
    READ ( *, IN, IOSTAT=STATS(V) )

ANSWERS:

1. According to 9.12p5

  "The value of a specifier in an input/output statement shall not
  depend on the definition or evaluation of any other specifier in the
  <io-control-spec-list> or <inquire-spec-list> in that statement."

the INQUIRE statements are prohibited because the values of the
variables EXIST and OPEN depend upon the values of the FILE= and UNIT=
specifiers, respectively.  They were intended to be permitted.  Edits
are provided to correct this mistake.

2. According to 9.12p6

  "The value of any subscript or substring bound of a variable that
  appears in a specifier in an input/output statement shall not depend
  on any <input-item>, <io-implied-do> <do-variable>, or on the
  definition or evaluation of any other specifier in the
  <io-control-spec> or <inquire-spec> in that statement."

the INQUIRE statement is not prohibited because U is not a subscript or
substring bound.  It was intended to be prohibited.  Edits are provided
to correct this mistake.

3. According to 9.12p5

  "The value of any subscript or substring bound of a variable that
  appears in a specifier in an input/output statement shall not depend
  on any <input-item>, <io-implied-do> <do-variable>, or on the
  definition or evaluation of any other specifier in the
  <io-control-spec> or <inquire-spec> in that statement."

and 9.12p7

  "In a data transfer statement, the variable specified in an IOSTAT=,
  IOMSG=, or SIZE= specifier, if any, shall not be associated with any
  entity in the ... <namelist-group-object-list>...."

and 9.12p8

  "In a data transfer statement, if a variable specified in an IOSTAT=,
  IOMSG=, or SIZE= specifier is an array element reference, its
  subscript values shall not be affected by the data transfer, the
  <io-implied-do> processing, or the definition or evaluation of any
  other specifier in the <io-control-spec-list>."

the READ statement is not prohibited because V does not "depend on any
<input-item>, <io-implied-do> <do-variable>, or on the definition or
evaluation of any other specifier in the <io-control-spec> or
<inquire-spec> in that statement."   Although V is input from namelist,
it is not "the variable specified in an IOSTAT=, IOMSG=, or SIZE=
specifier."  The READ statement was intended to be prohibited.  Edits
are provided to correct this mistake.

EDITS to 10-007r1:

[243:3-4 9.12p5] Within the first sentence, as amended by Corrigendum 2,
replace "input/output" with "data transfer" and delete "or
<inquire-spec-list>", so that the sentence, as amended by Corrigendum
2, becomes

  "The value of a specifier in a data transfer statement shall not
  depend on the evaluation of any other specifier in the
  <io-control-spec-list> in that statement."

If we assume that the UNIT= <file-unit-number>, FILE= <file-name-expr>,
or ID= <scalar-int-expr> in an <inquire-spec-list> are established
before the values of any of the <variable>s are changed, we need not
append

  "The value of a <file-unit-number>, <file-name-expr>, or
  <scalar-int-expr> in an <inquire-spec-list> shall not depend upon the
  definition of any variable in that <inquire-spec-list>."

[243:6, 12-15 9.12p6,8] Replace the paragraphs:

  "In an input/output statement, the value of any argument in a function
  reference that is a <variable>, any subscript, or any substring bound,
  that appears in a specifier in that statement, shall not be affected
  by data transfer or <implied-do> processing caused by that statement,
  or definition or evaluation of any other specifier in the
  <io-control-spec-list> or <inquire-spec-list> in that statement."