J3/10-178

To: J3
Subject: Interpretation concerning loop termination
From: Van Snyder
Date: 2010 June 10

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NUMBER: F08/xxxx
TITLE: Does a procedure reference cause loop termination?
KEYWORDS: branch, transfer of control, loop termination, procedure
          reference
DEFECT TYPE: Erratum
STATUS: Under consideration

QUESTION:

Consider the following DO construct

  DO
    CALL SUB
  END DO

According to subclause 8.1.6.6.4 in N1830, loop termination occurs when
"Control is transferred from a statement within the range of a DO
construct to a statement that is neither the <end-do> nor within the
range of the same DO construct."

A subroutine reference is a transfer of control.

The first executable statement of SUB is not within the range of the DO
construct.

Does the loop terminated when SUB is invoked?

ANSWER:

It is not intended that execution of a DO construct be terminated by a
procedure reference.  Edits are provided to correct this.

EDITS:

Replace the fourth item in the bulleted list in subclause 8.1.6.6.4 Loop
termination with the following:

"o A branch occurs within the range of a DO construct and the branch
   target statement is neither the <end-do> nor within the range of the
   same DO construct."

SUBMITTED BY: Van Snyder

HISTORY:

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