is a class type and
is not reference-related to T2
user-defined conversions are considered
using the rules for copy-initialization of an object of type
user-defined conversion ([dcl.init]
the program is ill-formed if the corresponding non-reference
copy-initialization would be ill-formed.
The result of the call to the
conversion function, as described for the non-reference
copy-initialization, is then used to direct-initialize the reference.