8 Statements [stmt.stmt]

for ( init-statement${}_{opt}$ for-range-declaration : for-range-initializer ) statement

{
	init-statement${}_{opt}$
	auto &&__range = for-range-initializer ;
	auto __begin = begin-expr ;
	auto __end = end-expr ;
	for ( ; __begin != __end; ++__begin ) {
		for-range-declaration = *__begin;
		statement
	}
}

• (1.1)
  if the for-range-initializer is an expression, it is regarded as if it were surrounded by parentheses (so that a comma operator cannot be reinterpreted as delimiting two init-declarators);
• (1.2)
  _­_­range, _­_­begin, and _­_­end are variables defined for exposition only; and
• (1.3)
  begin-expr and end-expr are determined as follows:
  • (1.3.1)
    if the for-range-initializer is an expression of array type R, begin-expr and end-expr are _­_­range and _­_­range + _­_­bound, respectively, where _­_­bound is the array bound.
    If R is an array of unknown bound or an array of incomplete type, the program is ill-formed;
  • (1.3.2)
    if the for-range-initializer is an expression of class type C, the unqualified-ids begin and end are looked up in the scope of C as if by class member access lookup ([basic.lookup.classref]), and if both find at least one declaration, begin-expr and end-expr are _­_­range.begin() and _­_­range.end(), respectively;
  • (1.3.3)
    otherwise, begin-expr and end-expr are begin(_­_­range) and end(_­_­range), respectively, where begin and end are looked up in the associated namespaces.
    [ Note

    :

    Ordinary unqualified lookup is not performed.

    — end note

     ]