Date: 2009-10-15.00:00:00

[Voted into WP at October, 2009 meeting.]

Date: 2009-07-15.00:00:00

Proposed resolution (July, 2009):

Change 9.5.5 [dcl.init.list] paragraph 4 as follows:

When an initializer list is implicitly converted to a An object of type std::initializer_list<E> is constructed from an initializer list, the object passed is constructed as if the implementation allocated an array of N elements of type E , where N is the number of elements in the initializer list. Each element of that array is copy-initialized with the corresponding element of the initializer list converted to E , and the std::initializer_list<E> object is constructed to refer to that array. If a narrowing conversion is required to convert the element to E initialize any of the elements, the program is ill-formed. [Example:...

Date: 2009-04-08.00:00:00

There are several problems with the wording of 9.5.5 [dcl.init.list] paragraph 4:

When an initializer list is implicitly converted to a std::initializer_list<E> , the object passed is constructed as if the implementation allocated an array of N elements of type E , where N is the number of elements in the initializer list. Each element of that array is initialized with the corresponding element of the initializer list converted to E , and the std::initializer_list<E> object is constructed to refer to that array. If a narrowing conversion is required to convert the element to E , the program is ill-formed.

First, an initializer list is not an expression, so it is not appropriate to refer to “implicitly convert[ing]” it, as is done in the first sentence.

Also, the conversion of the elements of the initializer list to the elements of the array is not specified to be either copy-initialization or direct-initialization. If this is intended to be viewed as an aggregate initialization, it would be copy-initialization, but that needs to be specified more clearly.

Finally, the initializer list can have nested initializer lists, so the references to converting the element also need to be cleaned up.