To:         J3                                       J3/14-191r2
From:       Van Snyder and Nick Maclaren and Steve Lionel
Subject:    Delete <do-block> and Range of the DO construct
Date: 2014 June 26
References: 14-007r1, 14-166

1. Introduction
===============

In 14-166, Malcolm recommended to delete the <do-block> syntax term and
the "Range of the DO construct" subclause.  We can't delete the "Range
of the DO construct" subclause without replacing references to "the
range of the loop" with "the <block> of the loop" in several places, and
prohibiting branching to the <end-do-stmt> from outside the construct.

Sections 3 and 4 describe this change.

Section 5 adds changes to forbid branching to all end construct
statements from outside the construct and make it a constraint.  This
could be regarded as fixing a historical defect.

Subclause 8.1.6.3 "Range of the DO construct" prohibits branching to an
<end-do> statement from outside the construct, but it is not a
constraint.

Prohibitions against branching to an <end-associate-stmt>,
<end-if-stmt>, <end-select-stmt>, or <end-select-type-stmt> are not
constraints, and are not in the subclause on branching.  There is no
prohibition against branching to an <end-block-stmt> or
<end-critical-stmt> from outside its construct (nor is there explicit
permission for it, as there once was for END IF).

2. Specification
================

Delete the <do-block> syntactic term and the "Range of the DO construct"
subclause.

Add a constraint to forbid branching to all end-construct
statements from outside their construct.

3. Edits to 14-007r1
====================

[xviii] Introduction

Add to the bullet "Data usage and computation" the sentence "The processor
is now required to be able to detect and report branching to the end
statement of an executable construct containing a block from outside the
construct."

[25:10+ 1.6.3p1+] Within the list of incompatibilities with Fortran
2008, add a list item:

    "Fortran 2008 did not prohibit branching to an <end-block-stmt> or
     <end-critical-stmt> from outside its construct.  This standard
     prohibits branching to those and requires the ability to detect
     and report such a branch."

[174:14 R813] Replace "<do-block>" with "<block>".

[175:5 R823] Delete R823 (the <do-block> syntax rule).

[175:15 8.1.6.3p1] Replace "<do-block>" with "<block> of the
<do-construct>".

[176:3 8.1.6.5.1p2] Replace "<do-block>" with "<block>".


4. Replacing "range"
====================

[46:25-26] Replace "range" with "<block>", twice.

[174:9.8.1.6.1p3] Replace "range" with "<block>".

[175:14-17 81.6.3] Delete "Range of the DO construct" subclause

[176:34 8.1.6.5.3p1(2)] Replace "range" with "<block>".

[177:5-6 8.1.6.5.3p3] Replace "range" with "<block>", twice.

[177:8 8.1.6.5.4p1] Replace "<range>" with "<block>".

[177:8-9 8.1.6.5.4p1] Replace "<range> of the loop" with "<block> of the
construct".

[177:11-12 C822] Replace "range" with "<block>", twice.

[177:29 8.1.6.5.5p1] Replace "range" with "<block>".

[177:31-33 8.1.6.5.5p1] Replace "range" with "<block>", thrice.

[178:23+5 Note 8.11] Replace "range" with "<block>".

[179:0+12 Note 8.14] Replace "range" with "<block>".

[179:0+25 Note 8.15] Replace "range" with "<block>".

[186:5 C846] Replace "range (8.1.6.3)" with "<block>".

[222:4-5 9.6.4.5.1p9] Replace "items that constitute the range of"
with "<input-item>s or <output-item>s within the"

5. Constraining against branching to <end-...-stmt> from
   outside its construct
========================================================


[187:12+ 8.2.1p1+] Insert a constraint:

"C847a If a branch target statement is an <end-associate-stmt>,
       <end-block-stmt>, <end-critical-stmt>, <end-do-stmt>,
       <end-if-stmt>, <end-select-stmt>, or <end-select-type-stmt>, the
       branching statement that references the label of that branch
       target statement shall be within the construct completed by that
       branch target statement."

[170:35 8.1.3.2p3] Delete the paragraph.

[180:29-30 8.1.7.2p2] Delete the paragraph.

[182:33 8.1.8.2p3] Delete the paragraph.

[185:33 8.1.9.2p9] Delete the paragraph.