Under the conditions specified in [dcl.init], as
part of an initialization of an object of non-class type,
a conversion function can be invoked to convert an initializer
expression of class type to the type of the object
Overload resolution is used to select the
conversion function to be invoked.
Assuming that “cv1T” is the
type of the object being initialized, and “cvS” is the type
of the initializer expression, with
a class type,
the candidate functions are selected as follows:
The conversion functions of
and its base classes are considered.
Those non-explicit conversion functions that are not hidden
and yield type
or a type that can be converted to type
via a standard conversion sequence
are candidate functions.
For direct-initialization, those explicit conversion functions that are not
hidden within S and yield type T or a type that can be converted
to type T with a qualification conversion are also
Conversion functions that return a cv-qualified type
are considered to yield the cv-unqualified version of that type
for this process of selecting candidate functions.
A call to a conversion function returning “reference to X”
is a glvalue of type X, and such a conversion function is
therefore considered to yield X for this process of selecting