3 Basic concepts [basic]

If the nested-name-specifier of a qualified-id nominates a class, the name specified after the nested-name-specifier is looked up in the scope of the class ([class.member.lookup]), except for the cases listed below. The name shall represent one or more members of that class or of one of its base classes (Clause [class.derived]). [ Note: A class member can be referred to using a qualified-id at any point in its potential scope ([basic.scope.class]).  — end note ] The exceptions to the name lookup rule above are the following:

• (1.1)

  the lookup for a destructor is as specified in [basic.lookup.qual];

• (1.2)

  a conversion-type-id of a conversion-function-id is looked up in the same manner as a conversion-type-id in a class member access (see [basic.lookup.classref]);

• (1.3)

  the names in a template-argument of a template-id are looked up in the context in which the entire postfix-expression occurs.

• (1.4)

  the lookup for a name specified in a using-declaration ([namespace.udecl]) also finds class or enumeration names hidden within the same scope ([basic.scope.hiding]).

In a lookup in which function names are not ignored34 and the nested-name-specifier nominates a class C:

• (2.1)

  if the name specified after the nested-name-specifier, when looked up in C, is the injected-class-name of C (Clause [class]), or

• (2.2)

  in a using-declarator of a using-declaration ([namespace.udecl]) that is a member-declaration, if the name specified after the nested-name-specifier is the same as the identifier or the simple-template-id's template-name in the last component of the nested-name-specifier,

the name is instead considered to name the constructor of class C. [ Note: For example, the constructor is not an acceptable lookup result in an elaborated-type-specifier so the constructor would not be used in place of the injected-class-name.  — end note ] Such a constructor name shall be used only in the declarator-id of a declaration that names a constructor or in a using-declaration. [ Example:

struct A { A(); };
struct B: public A { B(); };

A::A() { }
B::B() { }

B::A ba;            // object of type A
A::A a;             // error, A::A is not a type name
struct A::A a2;     // object of type A

 — end example ]

A class member name hidden by a name in a nested declarative region or by the name of a derived class member can still be found if qualified by the name of its class followed by the :: operator.