标准在哪里定义了将值绑定到引用的优先顺序？

Question

正如所解释的那样here，不同类别的值根据以下优先顺序绑定到不同种类的引用：

struct s {};

void f (      s&);  // #1
void f (const s&);  // #2
void f (      s&&); // #3
void f (const s&&); // #4

const s g ();
s x;
const s cx;

f (s ()); // rvalue        #3, #4, #2
f (g ()); // const rvalue  #4, #2
f (x);    // lvalue        #1, #2
f (cx);   // const lvalue  #2

标准中哪里描述了这种优先顺序？

Answer 1

[over.ics.rank]/3 - (3.1) Standard conversion sequence S1 is a better conversion sequence than standard conversion sequence S2 if

...

(3.1.3) — S1 and S2 are reference bindings (8.5.3) and neither refers to an implicit object parameter of a non-static member function declared without a ref-qualifier, and S1 binds an rvalue reference to an rvalue and S2 binds an lvalue reference.

...

(3.1.6) — S1 and S2 are reference bindings (8.5.3), and the types to which the references refer are the same type except for top-level cv-qualifiers, and the type to which the reference initialized by S2 refers is more cv-qualified than the type to which the reference initialized by S1 refers.

根据这些规则，采用右值引用的函数优于采用左值引用的函数，然后采用非 const 引用的函数优于采用 const 的函数。当然，只考虑可行的重载。