16 Overloading [over]

16.3 Overload resolution [over.match]

16.3.1 Candidate functions and argument lists [over.match.funcs]

16.3.1.3 Initialization by constructor [over.match.ctor]

When objects of class type are direct-initialized, copy-initialized from an expression of the same or a derived class type ([dcl.init]), or default-initialized, overload resolution selects the constructor.
For direct-initialization or default-initialization that is not in the context of copy-initialization, the candidate functions are all the constructors of the class of the object being initialized.
For copy-initialization, the candidate functions are all the converting constructors of that class.
The argument list is the expression-list or assignment-expression of the initializer.