[ Issues Telecon 16-Dec-2016 ]

Resolved by the adoption of P0501R0.

Addresses CH 3, CH 4, CH 5, CH 6, CH 8

1. variant allows reference types as alternatives; optional explicitly forbids to be instantiated for reference types. This is inconsistent.

2. variant<int, void> should be as usable as variant<int>.

3. variant<> should not have an index() function.

4. Clarify the intended behavior of variant for alternative types that are references.

5. Clarify variant construction.

Proposed change:

1. Consider allowing reference types for both or none.

2. —

3. Consider specifying a specialization for variant<> like:

   template<> 
   class variant<> 
   { 
   public: 
     variant() = delete; 
     variant(const variant&) = delete; 
     variant& operator=(variant const&) = delete;
   };
   

4. Add a respective note.

5. Add a note that variant<> cannot be constructed.