J3/03-239

Date:     August 19, 2003
To:       J3
From:     Matthijs van Waveren
Subject:  mask-expr interp

NUMBER: 000102
TITLE: mask-expr evaluated only once
KEYWORDS: WHERE
DEFECT TYPE: Erratum
STATUS: Submitted

QUESTION:

Is a mask-expr required to be evaluated in a WHERE such as:

      WHERE ( (/ .TRUE., .TRUE. /) )
        A = A + 1
      ELSE WHERE (MASKF())
        A = MAX
      END WHERE

where an optimizing compiler might notice that the ELSEWHERE
branch will never be executed ?

Page 112, line 38 says of the mask expression in ELSEWHERE statements

"The mask-expression is evaluated only once."

ANSWER:

No, it is not required to evaluate the mask-expr in a WHERE. An edit
is supplied to correct this oversight.

EDIT:

[112:30-31]  Change "only once" to "at most once"

[112:38]  Change "only once" to "at most once"

SUBMITTED BY: Matthijs van Waveren

HISTORY: 03-239     m165      Passed unanimously by J3 meeting