CV - qualifiers of an auto variable

Question

I found here the following "rule":

[...] auto drops const and volatile qualifiers only if they're at the top or right below an outermost reference [...]

I understand that top-level cv-qualifiers are a description of the variable itself (compared to the description of what it is pointing to or referencing). But when is a cv-qualifier "right below an outermost reference" and why would auto drop it (probably the first question answers the second one as well)?

Answer 1

"cv right below an outermost reference" means that the reference is to a cv-qualified type. For example, take this function:

const int& foo();

The type "right below the outermost reference" is const int, which means the const is there as well. In this code:

auto i = foo();

the type of i is int, not const int or const int&.

Examples of a constwhich is not right below an outermost reference are:

const char* bar();
const double* volatile & baz();

Using auto to take calls of these functions would deduce to type const char* and const double*, respectively.