What does a constant mean in an automatic return declaration with a return type?

I need to return a constant reference from a function. This code does the following:

auto test()->add_lvalue_reference<const int>::type
{
    static int i{50};
    return i;
}

int & i{test()}; // doesn't compile

      

        
        
        
      

    

But this snippet, which looks painfully similar, gives the wrong result:

auto const test()->add_lvalue_reference<int>::type
{
    static int i{50};
    return i;
}

int & i{test()}; // compiles thougth test() returned a const

      

        
        
        
      

    

I moved the keyword const

from the type declaration to the return declaration.

At first I thought that after deduction, the function signature became in the second case:

int & const test(); // not valid - const qualifiers cannot be applied to int&

      

        
        
        
      

    

This is invalid C ++. But with a auto

specifier, it compiles.

So my question is, what does it mean const

in the return type of an auto-return function? Or perhaps it threw it off?