According to 7.6.1.4 [expr.type.conv] paragraphs 1 and 3 (stated directly or by reference to another section of the Standard), all the following expressions create temporaries:

    T(1)
    T(1, 2)
    T{1}
    T{}

However, paragraph 2 says,

The expression T(), where T is a simple-type-specifier or typename-specifier for a non-array complete effective object type or the (possibly cv-qualified) void type, creates an rvalue of the specified type, which is value-initialized (9.5 [dcl.init]; no initialization is done for the void() case).

This does not say that the result is a temporary, which means that the lifetime of the result is not specified by 6.7.7 [class.temporary]. Presumably this is just an oversight.