[Bug c++/65520] New: elaborated-type-specifiers and inaccessible injected-class-names

["rs2740 at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65520

            Bug ID: 65520
           Summary: elaborated-type-specifiers and inaccessible
                    injected-class-names
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rs2740 at gmail dot com

Repro:

struct A {};
struct B : private A {};
struct C : public B {
    struct A m_a; // error: A is the inaccessible injected-class-name
};

Per [basic.lookup.elab]/p2, the elaborated-type-specifier `struct A` should
cause an unqualified name lookup for `A`, and per [basic.lookup.unqual]/p7 the
name is first searched in C and its base classes, which should find the
inaccessible injected-class-name, rendering the code ill-formed.

Instead, GCC accepts this code. It is rejected by all versions of Clang I
tested (3.0 and later).