[Bug c++/100335] New: Using statement of a ref-qualified method from base class: method not callable on derived object

[Daniel.Withopf at web dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100335

            Bug ID: 100335
           Summary: Using statement of a ref-qualified method from base
                    class: method not callable on derived object
           Product: gcc
           Version: 10.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Daniel.Withopf at web dot de
  Target Milestone: ---

The following code examples defines 2 ref-qualified method with identical names
in a base class (const& and const&&). Derived also defines a (non-const) method
with the same name and adds a "using Base::method;"

With all gcc Versions I tested (10.3, 9.3, 8.3, 7.5), the compilation with
--std=c++11 or --std=c++14 fails if the method in the derived class does not
have a ref-qualifier.

class Base {
public:
  void method() const&& {}
  void method() const& {}
};

class Derived : public Base {
public:
  using Base::method;
  // this leads to a compiler error
  void method() {}

  // with a ref-qualifier the code is compiling
  //  void method() & {}
};

int main() {
    const Derived test;
    test.method();
}

I believe that this is incorrect and the code should also compile when the
method in the Derived class has no ref-qualifier.