Movatterモバイル変換

[Moved to DR at the October, 2015 meeting.]

Proposed resolution (May, 2015):

1. Add a new production to the grammar in 9.5 [dcl.init] paragraph 1:

expr-or-braced-init-list:
expression
braced-init-list

2. Change the grammar in 7.6.1 [expr.post] paragraph 1as follows:

postfix-expression:
primary-expression
postfix-expression[expressionexpr-or-braced-init-list]
postfix-expression[braced-init-list]
postfix-expression(expression-list_opt)
...

3. Change the grammar in 8.6 [stmt.iter] paragraph 1as follows:

for-range-initializer:
expression
braced-init-list
expr-or-braced-init-list

4. Change 8.6.5 [stmt.ranged] paragraph 1 as follows:

For a range-basedfor statement of the form

for (for-range-declaration:expression)statement

letrange-init be equivalent to theexpressionsurrounded by parentheses⁹⁰

(expression)

and for a range-basedfor statement of the form

for (for-range-declaration:braced-init-list)statement

letrange-init be equivalent tothebraced-init-list. In each case,aA range-based for statement is equivalentto

  {  auto && __range =range-initfor-range-initializer;    for ( auto __begin = begin-expr,               __end = end-expr;          __begin != __end;          ++__begin ) {for-range-declaration = *__begin;statement    }  }

where

• if thefor-range-initializer is anexpression, it is regarded as if it were surroundedby parentheses (so that a comma operator cannot bereinterpreted as delimitingtwoinit-declarators);

• __range,__begin,and__end are variables defined for expositiononly,; and

• _RangeT is the type of the expression,and

• begin-expr andend-expr are determined asfollows:

• if_RangeTthefor-range-initializer is anexpressionof array typeR,begin-exprandend-expr are__range and__range +__bound, respectively, where__bound is thearraybound. If_RangeTRis an array of unknown size or an array of incomplete type,the program is ill-formed;

• if_RangeTthefor-range-initializer isaan expression of class typeC,theunqualified-idsbegin andendare looked up in the scope ofclass_RangeTC as if by class member access lookup(_N4868_.6.5.6 [basic.lookup.classref]), and if either (or both) findsat least one declaration,begin-exprandend-expr are__range.begin() and__range.end(),respectively;

• otherwise,begin-expr andend-expr arebegin(__range) andend(__range),respectively, wherebegin andend arelooked up in the associated namespaces(6.5.4 [basic.lookup.argdep]). [Note: Ordinaryunqualified lookup (6.5.3 [basic.lookup.unqual]) is notperformed. —end note]

5. Change the grammar of 8.8 [stmt.jump] paragraph 1as follows:

jump-statement:
break ;
continue ;
returnexpressionexpr-or-braced-init-list_opt;
returnbraced-init-list;
gotoidentifier;

6. Change 8.8.4 [stmt.return] paragraph 2 as follows:

Theexpressionorbraced-init-listexpr-or-braced-init-listof areturn statement is called its operand. Areturn statement...

7. Change 12.4.5 [over.sub] paragraph 1 as follows:

operator[] shall be a non-static member function withexactly one parameter. It implements the subscriptingsyntax

postfix-expression[expressionexpr-or-braced-init-list]

or

postfix-expression[braced-init-list]

Thus, a subscripting expression...

It would be helpful to have a single grammar term forexpression andbraced-init-list, which often occurtogether in the text. In particular, 8.6.5 [stmt.ranged] paragraph 1allows both, but the description of__RangeTrefers only to theexpression case; such errors would be lesslikely if the common term were available.