8 Expressions [expr]

8.1 Primary expressions [expr.prim]

8.1.4 Names [expr.prim.id]

8.1.4.2 Qualified names [expr.prim.id.qual]

qualified-id:
	nested-name-specifier template unqualified-id
nested-name-specifier:
	::
	type-name ::
	namespace-name ::
	decltype-specifier ::
	nested-name-specifier identifier ::
	nested-name-specifier template simple-template-id ::
The type denoted by a decltype-specifier in a nested-name-specifier shall be a class or enumeration type.
A nested-name-specifier that denotes a class, optionally followed by the keyword template ([temp.names]), and then followed by the name of a member of either that class ([class.mem]) or one of its base classes, is a qualified-id; [class.qual] describes name lookup for class members that appear in qualified-ids.
The result is the member.
The type of the result is the type of the member.
The result is an lvalue if the member is a static member function or a data member and a prvalue otherwise.
[Note
:
A class member can be referred to using a qualified-id at any point in its potential scope ([basic.scope.class]).
end note
]
Where class-name ​::​~ class-name is used, the two class-names shall refer to the same class; this notation names the destructor.
The form ~ decltype-specifier also denotes the destructor, but it shall not be used as the unqualified-id in a qualified-id.
[Note
:
A typedef-name that names a class is a class-name ([class.name]).
end note
]
The nested-name-specifier ​::​ names the global namespace.
A nested-name-specifier that names a namespace, optionally followed by the keyword template ([temp.names]), and then followed by the name of a member of that namespace (or the name of a member of a namespace made visible by a using-directive), is a qualified-id; [namespace.qual] describes name lookup for namespace members that appear in qualified-ids.
The result is the member.
The type of the result is the type of the member.
The result is an lvalue if the member is a function or a variable and a prvalue otherwise.
A nested-name-specifier that denotes an enumeration, followed by the name of an enumerator of that enumeration, is a qualified-id that refers to the enumerator.
The result is the enumerator.
The type of the result is the type of the enumeration.
The result is a prvalue.
In a qualified-id, if the unqualified-id is a conversion-function-id, its conversion-type-id shall denote the same type in both the context in which the entire qualified-id occurs and in the context of the class denoted by the nested-name-specifier.