Reference collapsing Rules, Universal Reference and the implementation of Std::forward () and Std::move ()

For reference collapsing, you can see this link. (It also speaks of the implementation of Std::forward () and Std::move ())

Http://thbecker.net/articles/rvalue_references/section_08.html

It is important to note that in the case of Auto-type deduction and Template-type deduction, there will be reference-stripping: (from Scott Meyers)

Note that if doing reference collapsing, reference would be stripped first:

Things get subtler when deducing the type for a variable so is itself a reference.  The reference part of the type is ignored. For example, given

         int x;         ...         int&& r1 = ten;                   R1 ' s type is int&&         int& r2 = x;                     R2 ' s type is int&

The type for both and was considered to being in a call to the r1 r2 int template f . This reference-stripping behavior are independent of the rule that, during type deduction for universal references, lvalues T& T is deduced to is of type and rvalues of type, so given these calls,

         f (R1);         f (R2);

The deduced type for both and is r1 r2 int& . Why? First the reference parts of r1 ' s r2 and ' s types is stripped off (yielding int in both cases), then, because each is a lvalue, each are treated as int& during type deduction for the Universal reference parameter f From: "Nitty gritty Detail" of Https://isocpp.org/blog/2012/11/universal-references-in-c11-scott-meyers)

Reference collapsing Rules, Universal Reference and the implementation of Std::forward () and Std::move ()