Usual unqualified lookup and Argument-dependent name lookup(ADL)

Question

For unqualified name lookup, 'Usual unqualified lookup' and 'Argument-dependent name lookup'(ADL), I cannot find in standard which one happens first ?

Again as both trying to add something to the overload candidate set, the order doesn't seems to be matter though. But would still be nice to know which one happens first.

Thanks

Answer 1

It doesn't matter which comes first, does it? Name lookup generates a set of possible names.

3.4 Name lookup
Name lookup may associate more than one declaration with a name if it finds the name to be a function name; the declarations are said to form a set of overloaded functions.

The standard specifically says "set". As a mathematical construct, the set {1,2,3} is the same as {2,3,1} and {3,2,1}. Order doesn't matter. What does matter is when overload resolution and the application access rules occurs. Here the standard is very clear. Quoting once again from the intro paragraph to 3.4:

Overload resolution takes place after name lookup has succeeded. The access rules are considered only once name lookup and function overload resolution have succeeded.