[Bug c++/102170] New: False accept of class member access using qualified-id in case of ambiguity

[fchelnokov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102170

            Bug ID: 102170
           Summary: False accept of class member access using qualified-id
                    in case of ambiguity
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fchelnokov at gmail dot com
  Target Milestone: ---

In this program there is an ambiguity in qualified-id member access .D::
```
template<int N> struct A{ int v = N; using D = A; };
struct B : A<1>, A<2> {};
using D = A<1>;
int main() { return B{}.D::v; }
```
This program must be rejected (as Clang does). But GCC accepts it now,
incorrectly using global D
https://gcc.godbolt.org/z/74qraoeac