/// using directives by the given context.
///
/// C++98 [namespace.qual]p2:
-/// Given X::m (where X is a user-declared namespace), or given ::m
+/// Given X::m (where X is a user-declared namespace), or given \::m
/// (where X is the global namespace), let S be the set of all
/// declarations of m in X and in the transitive closure of all
/// namespaces nominated by using-directives in X and its used
/// (namespace.udecl), S is the required set of declarations of
/// m. Otherwise if the use of m is not one that allows a unique
/// declaration to be chosen from S, the program is ill-formed.
+///
/// C++98 [namespace.qual]p5:
/// During the lookup of a qualified namespace member name, if the
/// lookup finds more than one declaration of the member, and if one