To: J3                                                     J3/22-109r1
From: John Reid & Jon Steidel
Subject: Locality spec limitations
Date: 2022-March-01
References: 18-007r1

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NUMBER: F18/0xx
TITLE: Locality spec limitations
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

BACKGROUND

In 11.1.7.2 Form of the DO construct, C1128 states
"A <variable-name> that appears in a LOCAL or LOCAL_INIT <locality-spec>
shall not have the ALLOCATABLE, INTENT (IN), or OPTIONAL attribute,
shall not be of finalizable type, shall not be a nonpointer polymorphic
dummy argument, and shall not be a coarray or an assumed-size array."

QUESTION 1:

Was it intended to allow a variable with an ultimate component of
finalizable type here?

QUESTION 2:

Was it intended to allow a variable with a coarray ultimate component
here?

QUESTION 3:

Was it intended to allow a variable with an allocatable ultimate component
here?

ANSWER 1:

A variable with an ultimate component of finalizable type should not
be allowed here. Final subroutines may have side effects that make them
unsuitable for concurrent execution. An edit is suggested.

ANSWER 2:

A variable with a coarray ultimate component should not be allowed here.
If such a variable has an allocated coarray ultimate component and appears
in a LOCAL_INIT <locality-spec>, the corresponding construct variable
would be initialized to have its value, which would involve allocating the
coarray ultimate component and coarray synchronization. There is no
requirement for a DO CONCURRENT construct to be executed on all images of
the current team. An edit is suggested.

ANSWER 3:

A variable with an allocatable ultimate component of should not be allowed
here for consistency with the rule for variables quoted above. An edit is
suggested.


EDIT to 18-007r1:

[181:22-24] In 11.1.7.2 Form of the DO construct, C1128, sentence 1, after
"finalizable type" add "or of a type that has an ultimate component of
finalizable type," and change "and shall not be a coarray or" to
"shall not be a coarray or of a type that has an allocatable ultimate
component, and shall not be" so that the sentence reads
"A <variable-name> that appears in a LOCAL or LOCAL_INIT <locality-spec>
shall not have the ALLOCATABLE, INTENT (IN), or OPTIONAL attribute,
shall not be of finalizable type or of a type that has an ultimate
component of finalizable type, shall not be a nonpointer polymorphic
dummy argument, shall not be a coarray or of a type that has an
allocatable ultimate component, and shall not be an assumed-size array."

SUBMITTED BY: John Reid

HISTORY: 22-xxx   m226 Submitted