CWG Issue 90 (original) (raw)

This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 117a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2025-04-13

90. Should the enclosing class be an "associated class" too?

Section: 6.5.4 [basic.lookup.argdep]Status: TC1Submitter: John SpicerDate: 2 Feb 1999

Section 6.5.4 [basic.lookup.argdep] includes the following:

• If T is a class type, its associated classes are the class itself and its direct and indirect base classes. Its associated namespaces are the namespaces in which its associated classes are defined.

• If T is a union or enumeration type, its associated namespace is the namespace in which it is defined. If it is a class member, its associated class is the member's class; else it has no associated class. Note that for a union, the enclosing class is an "associated class", but for a class type the enclosing class is not an "associated class". This results in some surprising behavior, as shown in the example below.

  struct A { union U {}; friend void f(U); };

  struct B { struct S {}; friend void f(S); };

  int main() { A::U u; f(u); // okay: A is an associated class B::S s; f(s); // error: no matching f(), B is not an associated class }

Certainly the enclosing class should also be an associated class for nested class types, shouldn't it?

**Proposed Resolution (10/99):**Change the two referenced bullets to read:

• If T is a class type (including unions), its associated classes are: the class itself; the class of which it is a member, if any; and its direct and indirect base classes. Its associated namespaces are the namespaces in which its associated classes are defined.
• If T is an enumeration type, its associated namespace is the namespace in which it is defined. If it is class member, its associated class is the member's class; else it has no associated class. (This proposal also addressesCore issue 91.)