decltype(auto) vs auto&& to conserve cv qualifier
c++11, c++14
Solution
Supposing the function returns a `const &` reference, since `const` object and `const &&` are fairly useless return types, `decltype(auto)` will do the same thing as `auto &&`.
You should generally not use `decltype(auto)` for local variables as it has no particular use case, and obscures whether the declared entity is an object or a reference.
Problem
Is there an advantage to use the c++14 feature decltype(auto) vs auto&& for keeping cv qualifier ? ``` auto v = const_return_func() //strip the constness auto&& v = const_return_func() decltype(auto) = const_return_func() ```