J3/09-248r1
To: J3
From: Van Snyder/Stan Whitlock
Subject: Some IEEE elemental procedures should be impure elemental
Date: 2009 August 10
References: 09-007r2

1.  Introduction

The flags IEEE_DIVIDE_BY_ZERO, IEEE_INEXACT, IEEE_INVALID, IEEE_OVERFLOW,
and IEEE_UNDERFLOW, and the IEEE HALTING mode, can be regarded as either
global variables or save variables.

As such, the two subroutines to set them ought not to be pure.

NB: the two elemental functions that get these flags are still pure.

This potentially has an impact on existing software, as pure procedures
can presently invoke these procedures.

2.  Edits w.r.t. 09-007r2

Replace "Pure subroutine" by "Subroutine" at the following two places:

 [416:40 14.11.19p2] [417:12 14.11.20p2]

[24:11 1.6.2p1]---------------------------------------------------------
Editor: Replace "This part" by "Except as identified in this subclause,
        this part"

[24:13 1.6.2p1]--------------------------------------------------------
Editor: At the end of the paragraph, insert

  "The following Fortran 2003 features may have different interpretations
   in this part of ISO/IEC 1539.

     o The subroutines IEEE_SET_FLAG and IEEE_SET_HALTING_MODE in the
       intrinsic module IEEE_EXCEPTIONS were pure subroutines in Fortran
       2003.  They are not pure in Fortran 2008.  These two procedures
       cannot be invoked from pure procedures in a program that conforms
       to this part of ISO/IEC 1539."