This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 110b. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2023-01-15


588. Searching dependent bases of classes local to function templates

Section: 13.8.3  [temp.dep]     Status: CD2     Submitter: James Widman     Date: 21 June 2006

[Voted into the WP at the March, 2009 meeting.]

13.8.3 [temp.dep] paragraph 3 reads,

In the definition of a class template or a member of a class template, if a base class of the class template depends on a template-parameter, the base class scope is not examined during unqualified name lookup either at the point of definition of the class template or member or during an instantiation of the class template or member.

This wording applies only to definitions of class templates and members of class templates. That would make the following program ill-formed (but it probably should be well-formed):

    struct B{ void f(int); };

    template<class T> struct D: B { };

    template<class T> void g() {
       struct B{ void f(); };
       struct A: D<T> {
           B m;
       };
       A a;
       a.m.f(); // Presumably, we want ::g()::B::f(), not ::B::f(int)
    }

    int main () {
       g<int>();
       return 0;
    }

I suspect the wording should be something like

In the definition of a class template or a class defined (directly or indirectly) within the scope of a class template or function template, if a base class...

That should also include deeply nested classes in templates, local classes of non-template member functions of member classes of class templates, etc.

Proposed resolution (October, 2006):

Change 13.8.3 [temp.dep] paragraph 3 as follows:

In the definition of a class or class template or a member of a class template, if a base class of the class template depends on a template-parameter, the base class scope is not examined during unqualified name lookup either at the point of definition of the class template or member or during an instantiation of the class template or member.