Movatterモバイル変換

[Voted into the WP at the February, 2012 meeting;moved to DR at the October, 2012 meeting.]

Proposed resolution (August, 2011):

Change 9.5.5 [dcl.init.list] paragraph 3 as follows:

• ...

• Otherwise, ifT is a class type, constructors areconsidered...

• Otherwise, ifT is a reference type, a prvaluetemporary of the type referenced byT is list-initialized,and the reference is bound to that temporary. [Note: As usual,the binding will fail and the program is ill-formed if the referencetype is an lvalue reference to a non-const type. —endnote] [Example: ... —endexample]

• Otherwise, if the initializer list has a single elementoftypeE and eitherT is not a reference type or itsreferenced type is reference-related toE, the objector reference is initialized from that element; if a narrowingconversion (see below) is required to convert the element toT, the program is ill-formed. [Example:...

• Otherwise, ifT is a reference type, a prvaluetemporary of the type referenced byT is list-initialized,and the reference is bound to that temporary. [Note: As usual,the binding will fail and the program is ill-formed if the referencetype is an lvalue reference to a non-const type. —endnote] [Example: ... —endexample]

• Otherwise, if the initializer list has no elements...

• ...

One might expect that in an example like

  int i;  int & ir{i};

ir would bind directly toi. However, accordingto 9.5.5 [dcl.init.list] paragraph 3, this example creates atemporary of typeint and binds the reference to thattemporary:

• ...

• Otherwise, ifT is a reference type, a prvaluetemporary of the type referenced byT is list-initialized,and the reference is bound to that temporary...

• Otherwise, if the initializer list has a single element, theobject or reference is initialized from that element...

Also, the “or reference” in the last bullet is deadcode, as a reference initialization is always handled by the precedingbullet.