13 July 2006                                                                            J3/06-196


Sub ject:    Questions about DO CONCURRENT
From:        Van Snyder


The provisions of the enumerated list in 8.1.7.5.4 Loop termination explicitly do not apply to a DO
CONCURRENT construct. Rather, a separate paragraph specifies that a DO CONCURRENT con-
struct terminates when all the iterations complete execution. There is no constraint against a RETURN
statement appearing within a DO CONCURRENT construct, and no prohibition (that I could find)
against one being executed within an iteration. Thus it appears that execution of a RETURN statement
does return from the procedure in which it is executed, but if it's within the range of a DO CONCUR-
RENT construct, the construct nonetheless continues to be active. Even more absurdly, if execution
of the program is terminated by execution of a STOP statement or for another reason while a DO
CONCURRENT construct is active, execution of the program terminates but the DO CONCURRENT
construct remains active.
Should there be a constraint against a RETURN statement appearing within the range of a DO CON-
CURRENT construct? If not, does execution of such a RETURN statement terminate execution of the
loop?
Does execution of a STOP statement or termination of the program for another reason terminate exe-
cution of the loop?




13 July 2006                                                                          Page 1 of 1