Chapter 4, Advanced Template Concepts
When is name lookup performed?
Name lookup is performed at the point of template instantiation for dependent names (those that depend on the type or value of a template parameter) and at the point of template definition for non-dependent names (those that don’t depend on template parameters).
What are deduction guides?
Deduction guides are a mechanism that tells the compiler how to perform class template argument deduction. Deduction guides are fictional function templates representing constructor signatures of a fictional class type. If overload resolution fails on the constructed set of fictional function templates, then the program is ill-formed and an error is generated. Otherwise, the return type of the selected function template specialization becomes the deduced class template specialization.
What are forwarding references?
A forward reference...