C++ auto vs auto&

Question

if I have a function:

Foo& Bar()
{
   return /// do something to create a non-temp Foo here and return a reference to it
}

why is this:

Answer 1

The type deduction for auto works exactly the same as for templates:

• when you deduce auto you will get a value type.
• when you deduce auto& you wil get a non-const reference type
• when you deduce const auto& you will get a const reference
• when you deduce auto&& you will get
  • a non-const reference if you assign a non-const reference
  • a const reference if you assign a const reference
  • a value when you assign a temporary

Answer 2

Taken directly from Herb Sutter's blog post:

auto means “take exactly the type on the right-hand side, but strip off top-level const/volatile and &/&&.”