Bug 66957

class BaseClass {
protected:
  static int x;
};

struct DerivedA : BaseClass { };

struct DerivedB : BaseClass {
  DerivedB() {
    (void) DerivedA::x;
  }
};

This seems to have been broken by the fix for bug 38579.  I'll revert it in the open release branches.

Author: jason
Date: Tue Aug 18 14:43:44 2015
New Revision: 226974

URL: https://gcc.gnu.org/viewcvs?rev=226974&root=gcc&view=rev
Log:
	PR c++/66957
	* search.c (protected_accessible_p): Revert fix for 38579.

Added:
    branches/gcc-4_9-branch/gcc/testsuite/g++.dg/inherit/access9.C
Modified:
    branches/gcc-4_9-branch/gcc/cp/ChangeLog
    branches/gcc-4_9-branch/gcc/cp/search.c
    branches/gcc-4_9-branch/gcc/testsuite/g++.dg/conversion/access1.C

Author: jason
Date: Tue Aug 18 14:44:06 2015
New Revision: 226975

URL: https://gcc.gnu.org/viewcvs?rev=226975&root=gcc&view=rev
Log:
	PR c++/66957
	* search.c (protected_accessible_p): Revert fix for 38579.

Added:
    branches/gcc-5-branch/gcc/testsuite/g++.dg/inherit/access9.C
Modified:
    branches/gcc-5-branch/gcc/cp/ChangeLog
    branches/gcc-5-branch/gcc/cp/search.c
    branches/gcc-5-branch/gcc/testsuite/g++.dg/conversion/access1.C

Author: jason
Date: Thu Aug 20 01:45:49 2015
New Revision: 227023

URL: https://gcc.gnu.org/viewcvs?rev=227023&root=gcc&view=rev
Log:
	PR c++/66957
	* search.c (protected_accessible_p): Remove redundant access_in_type.
	Add otype parm instead of walking binfo.
	(friend_accessible_p): Check SCOPE itself.  Handle class
	templates.  Pass through otype.
	(dfs_accessible_post): Handle all accessibility cases.
	(dfs_accessible_pre): New.
	(accessible_p): Use it.  Don't check protected access here.  Pass
	decl and otype to dfs_walk.
	(member_declared_in_type, dfs_access_in_type_pre): New.
	(access_in_type): Use dfs_access_in_type_pre.
	* friend.c (add_friend): Fix multiple friends with the same name.

Added:
    trunk/gcc/testsuite/g++.dg/inherit/access9.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/friend.c
    trunk/gcc/cp/search.c

Fixed for 4.9.4, 5.3, 6.0.

For what it's worth, this patch looked like it might also fix
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58972, and it
does.

The fix for this bug seems to have broken N4381-style customization points (http://wg21.link/n4381). To wit, this program used to compile:

template <class T> T&& declval();

namespace X {
  namespace Y {
    int f(auto&&);

    struct fn {
      constexpr auto operator()(auto&& o) const {
        return f(o);
      }
    };
  }
  namespace {
    constexpr auto f = Y::fn{};
  }

  struct A {};

  struct B {
    friend double f(B&);
  };
}

static_assert(__is_same_as(int, decltype(X::f(declval<X::A&>()))));
static_assert(__is_same_as(double, decltype(X::f(declval<X::B&>()))));

but now results in the error "error: ‘f’ is not a member of ‘X’" for both static_asserts. It's possible to workaround the error be declaring the anonymous namespace inline:

inline namespace {
  constexpr auto f = Y::fn{};
}

It appears that the non-visible friend function f declared in B is incorrectly blocking name lookup of X::f before the phase of lookup that considers namespaces nominated by using directives (such as unnamed namespaces).