[Bug c++/84884] New: [DR 2244] [C++17] protected constructor and aggregate initialization of base

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84884

            Bug ID: 84884
           Summary: [DR 2244] [C++17] protected constructor and aggregate
                    initialization of base
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jason at gcc dot gnu.org
  Target Milestone: ---

Here we should accept f and g because we're using the protected constructor on
a base of a B object, so friendship makes it OK:

struct A {
protected:
  A();
};
struct B : A {
  friend B f();
  friend B g();
  friend B h();
};
B f() { return {}; } // ok
B g() { return {{}}; } // ok
B h() { return {A{}}; } // error

This will need significant changes to build_aggr_conv.