c++: diagnose failed qualified lookup into current inst

When the scope of a qualified name is the current instantiation, and
qualified lookup finds nothing at template definition time, then we
know it'll find nothing at instantiation time (unless the current
instantiation has dependent bases).  So such qualified name lookup
failure can be diagnosed ahead of time as per [temp.res.general]/6.

This patch implements that, for qualified names of the form (where
the current instantiation is A<T>):

  this->non_existent
  a.non_existent
  A::non_existent
  typename A::non_existent

It turns out we already optimistically attempt qualified lookup of
seemingly every qualified name, even when it's dependently scoped, and
then suppress issuing a lookup failure diagnostic after the fact.
So implementing this is mostly a matter of restricting the diagnostic
suppression to "dependentish" scopes (i.e. dependent scopes or the
current instantiation with dependent bases), rather than suppressing
for any dependently-typed scope as we currently do.

The cp_parser_conversion_function_id change is needed to avoid regressing
lookup/using8.C:

  using A<T>::operator typename A<T>::Nested*;

When looking up A<T>::Nested we consider it not dependently scoped since
we entered A<T> from cp_parser_conversion_function_id earlier.   But this
A<T> is the implicit instantiation A<T> not the primary template type A<T>,
and so the lookup fails which we now diagnose.  This patch works around
this by not entering the template scope of a qualified conversion
function-id in this case, i.e. if we're in an expression vs declaration
context, by seeing if the type already went through finish_template_type
with entering_scope=true.

gcc/cp/ChangeLog:

	* decl.cc (make_typename_type): Restrict name lookup failure
	punting to dependentish_scope_p instead of dependent_type_p.
	* error.cc (qualified_name_lookup_error): Improve diagnostic
	when the scope is the current instantiation.
	* parser.cc (cp_parser_diagnose_invalid_type_name): Likewise.
	(cp_parser_conversion_function_id): Don't call push_scope on
	a template scope unless we're in a declaration context.
	(cp_parser_lookup_name): Restrict name lookup failure
	punting to dependentish_scope_p instead of depedent_type_p.
	* semantics.cc (finish_id_expression_1): Likewise.
	* typeck.cc (finish_class_member_access_expr): Likewise.

libstdc++-v3/ChangeLog:

	* include/experimental/socket
	(basic_socket_iostream::basic_socket_iostream): Fix typo.
	* include/tr2/dynamic_bitset
	(__dynamic_bitset_base::_M_is_proper_subset_of): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/alignas18.C: Expect name lookup error for U::X.
	* g++.dg/cpp0x/forw_enum13.C: Expect name lookup error for
	D3::A and D4<T>::A.
	* g++.dg/parse/access13.C: Declare A::E::V to avoid name lookup
	failure and preserve intent of the test.
	* g++.dg/parse/enum11.C: Expect extra errors, matching the
	non-template case.
	* g++.dg/template/crash123.C: Avoid name lookup failure to
	preserve intent of the test.
	* g++.dg/template/crash124.C: Likewise.
	* g++.dg/template/crash7.C: Adjust expected diagnostics.
	* g++.dg/template/dtor6.C: Declare A::~A() to avoid name lookup
	failure and preserve intent of the test.
	* g++.dg/template/error22.C: Adjust expected diagnostics.
	* g++.dg/template/static30.C: Avoid name lookup failure to
	preserve intent of the test.
	* g++.old-deja/g++.other/decl5.C: Adjust expected diagnostics.
	* g++.dg/template/non-dependent34.C: New test.

Reviewed-by: Jason Merrill <jason@redhat.com>

19 files changed, 74 insertions, 26 deletions

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 66e8a97..6b686d7 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -4536,7 +4536,7 @@ make_typename_type (tree context, tree name, enum tag_types tag_type,
   else
     t = NULL_TREE;
 
-  if ((!t || TREE_CODE (t) == TREE_LIST) && dependent_type_p (context))
+  if ((!t || TREE_CODE (t) == TREE_LIST) && dependentish_scope_p (context))
     return build_typename_type (context, name, fullname, tag_type);
 
   want_template = TREE_CODE (fullname) == TEMPLATE_ID_EXPR;
diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc
index e35448f..6d99cb2 100644
--- a/gcc/cp/error.cc
+++ b/gcc/cp/error.cc
@@ -4714,7 +4714,8 @@ qualified_name_lookup_error (tree scope, tree name,
     ; /* We already complained.  */
   else if (TYPE_P (scope))
     {
-      if (!COMPLETE_TYPE_P (scope))
+      if (!COMPLETE_TYPE_P (scope)
+	  && !currently_open_class (scope))
 	error_at (location, "incomplete type %qT used in nested name specifier",
 		  scope);
       else if (TREE_CODE (decl) == TREE_LIST)
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 1dd0efa..efd5d6f 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -3888,7 +3888,8 @@ cp_parser_diagnose_invalid_type_name (cp_parser *parser, tree id,
       else if (TYPE_P (parser->scope))
 	{
 	  auto_diagnostic_group d;
-	  if (!COMPLETE_TYPE_P (parser->scope))
+	  if (!COMPLETE_TYPE_P (parser->scope)
+	      && !currently_open_class (parser->scope))
 	    cxx_incomplete_type_error (location_of (id), NULL_TREE,
 				       parser->scope);
 	  else if (cp_lexer_next_token_is (parser->lexer, CPP_LESS))
@@ -17514,7 +17515,10 @@ cp_parser_conversion_function_id (cp_parser* parser)
 
      In order to see that `I' is a type-name in the definition, we
      must be in the scope of `S'.  */
-  if (saved_scope)
+  if (saved_scope
+      /* In A<T>::operator I(), we don't want to enter A<T> if we're
+	 in an expression rather than declaration context.  */
+      && adjust_type_for_entering_scope (saved_scope) == saved_scope)
     pushed_scope = push_scope (saved_scope);
   /* Parse the conversion-type-id.  */
   type = cp_parser_conversion_type_id (parser);
@@ -32219,7 +32223,7 @@ cp_parser_lookup_name (cp_parser *parser, tree name,
       /* If the scope is a dependent type and either we deferred lookup or
 	 we did lookup but didn't find the name, rememeber the name.  */
       if (decl == error_mark_node && TYPE_P (parser->scope)
-	  && dependent_type_p (parser->scope))
+	  && dependentish_scope_p (parser->scope))
 	{
 	  if (tag_type)
 	    {
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index cd3df13..c21572e 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -4353,7 +4353,7 @@ finish_id_expression_1 (tree id_expression,
 	  /* Name lookup failed.  */
 	  if (scope
 	      && (!TYPE_P (scope)
-		  || (!dependent_type_p (scope)
+		  || (!dependentish_scope_p (scope)
 		      && !(identifier_p (id_expression)
 			   && IDENTIFIER_CONV_OP_P (id_expression)
 			   && dependent_type_p (TREE_TYPE (id_expression))))))
diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
index 15e5577..8df8b87 100644
--- a/gcc/cp/typeck.cc
+++ b/gcc/cp/typeck.cc
@@ -3542,7 +3542,7 @@ finish_class_member_access_expr (cp_expr object, tree name, bool template_p,
 	  afi.maybe_suggest_accessor (TYPE_READONLY (object_type));
 	  if (member == NULL_TREE)
 	    {
-	      if (dependent_type_p (object_type))
+	      if (dependentish_scope_p (object_type))
 		/* Try again at instantiation time.  */
 		goto dependent;
 	      if (complain & tf_error)
diff --git a/gcc/testsuite/g++.dg/cpp0x/alignas18.C b/gcc/testsuite/g++.dg/cpp0x/alignas18.C
index 820bdd2..9c25cd0 100644
--- a/gcc/testsuite/g++.dg/cpp0x/alignas18.C
+++ b/gcc/testsuite/g++.dg/cpp0x/alignas18.C
@@ -3,6 +3,5 @@
 
 template <typename T> struct S {
   using U = S;
-  // FIXME: This is ill-formed; see PR90847.
-  void fn() alignas(U::X);
+  void fn() alignas(U::X); // { dg-error "not a member" }
 };
diff --git a/gcc/testsuite/g++.dg/cpp0x/forw_enum13.C b/gcc/testsuite/g++.dg/cpp0x/forw_enum13.C
index b8027f0..37ffad9 100644
--- a/gcc/testsuite/g++.dg/cpp0x/forw_enum13.C
+++ b/gcc/testsuite/g++.dg/cpp0x/forw_enum13.C
@@ -18,13 +18,13 @@ class D2
 template <typename T>
 class D3
 {
-  enum D3::A { foo } c; // { dg-error "extra qualification not allowed" }
+  enum D3::A { foo } c; // { dg-error "does not name an enumeration" }
 };
 
 template <typename T>
 class D4
 {
-  enum D4<T>::A { foo } c; // { dg-error "extra qualification not allowed" }
+  enum D4<T>::A { foo } c; // { dg-error "does not name an enumeration" }
 };
 
 template <typename T>
@@ -32,7 +32,7 @@ class D5
 {
   class D6
   {
-    enum D6::A { foo } c; // { dg-error "extra qualification not allowed" }
+    enum D6::A { foo } c; // { dg-error "does not name an enumeration" }
   };
 };
 
diff --git a/gcc/testsuite/g++.dg/parse/access13.C b/gcc/testsuite/g++.dg/parse/access13.C
index 41463c5..ea3cf11 100644
--- a/gcc/testsuite/g++.dg/parse/access13.C
+++ b/gcc/testsuite/g++.dg/parse/access13.C
@@ -2,6 +2,7 @@
 
 template <typename> struct A
 {
+  struct E { static int V; };
   A::E::V;		       // { dg-warning "access decl" }
   enum { V };		       // { dg-error "conflicts with a previous decl" }
 };
diff --git a/gcc/testsuite/g++.dg/parse/enum11.C b/gcc/testsuite/g++.dg/parse/enum11.C
index 68ddedb..8bab16a 100644
--- a/gcc/testsuite/g++.dg/parse/enum11.C
+++ b/gcc/testsuite/g++.dg/parse/enum11.C
@@ -2,5 +2,5 @@
 
 template<typename> struct A
 { 
-  enum A::B::C {};   // { dg-error "has not been declared" }
+  enum A::B::C {};   // { dg-error "" }
 };
diff --git a/gcc/testsuite/g++.dg/template/crash123.C b/gcc/testsuite/g++.dg/template/crash123.C
index 20a4961..20a71cf 100644
--- a/gcc/testsuite/g++.dg/template/crash123.C
+++ b/gcc/testsuite/g++.dg/template/crash123.C
@@ -4,7 +4,7 @@ template <bool> struct VI {};
 template <typename T>
 struct IP
 {
-  static const bool r = IP<T>::r;  // { dg-error "depth" }
+  static const bool r = IP<T*>::r;  // { dg-error "depth" }
 };
 template <typename T> struct V
 {
diff --git a/gcc/testsuite/g++.dg/template/crash124.C b/gcc/testsuite/g++.dg/template/crash124.C
index 4931aa8..5788ead 100644
--- a/gcc/testsuite/g++.dg/template/crash124.C
+++ b/gcc/testsuite/g++.dg/template/crash124.C
@@ -4,12 +4,12 @@ template <bool> struct VI {};
 template <typename T>
 struct IP
 {
-  static const bool r = IP<T>::r;  // { dg-error "depth" }
+  static const bool r = IP<T*>::r;  // { dg-error "depth" }
 };
 template <typename T>
 struct V
 {
-  static const bool r = IP<T>::r;
+  static const bool r = IP<T*>::r;
   VI<r> vi;
 };
 struct X;
diff --git a/gcc/testsuite/g++.dg/template/crash7.C b/gcc/testsuite/g++.dg/template/crash7.C
index 691628e..977b4e4 100644
--- a/gcc/testsuite/g++.dg/template/crash7.C
+++ b/gcc/testsuite/g++.dg/template/crash7.C
@@ -7,9 +7,7 @@
 
 template <typename> struct A
 {
-    template <typename> A(typename A::X) {} // { dg-error "incomplete" }
+    template <typename> A(typename A::X) {} // { dg-error "does not name a type" }
 };
 
-// We currently don't give the "no match" error because we don't add the
-// invalid constructor template to TYPE_METHODS.
-A<void> a;			// { dg-message "required" }
+A<void> a;			// { dg-error "no match" }
diff --git a/gcc/testsuite/g++.dg/template/dtor6.C b/gcc/testsuite/g++.dg/template/dtor6.C
index a3d778a1..46ebf9f 100644
--- a/gcc/testsuite/g++.dg/template/dtor6.C
+++ b/gcc/testsuite/g++.dg/template/dtor6.C
@@ -3,6 +3,7 @@
 template<int> struct A
 {
   static int i;
+  ~A();
 };
 
 template<int N> int A<N>::i = { A::~A }; // { dg-error "36:invalid use of non-static member function" }
diff --git a/gcc/testsuite/g++.dg/template/error22.C b/gcc/testsuite/g++.dg/template/error22.C
index a7e6172..af87992 100644
--- a/gcc/testsuite/g++.dg/template/error22.C
+++ b/gcc/testsuite/g++.dg/template/error22.C
@@ -4,6 +4,6 @@ struct A
 {
     template<void (A::*)()> struct B {};
     void ::foo(); // { dg-error "10:invalid use" }
-    B<&A::foo> b; // { dg-error "incomplete type|template argument" }
+    B<&A::foo> b; // { dg-error "'foo' is not a member of 'A'|template argument" }
 };
  
diff --git a/gcc/testsuite/g++.dg/template/non-dependent34.C b/gcc/testsuite/g++.dg/template/non-dependent34.C
new file mode 100644
index 0000000..4f369ff
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/non-dependent34.C
@@ -0,0 +1,44 @@
+// Verify we diagnose failed qualified lookup into the current
+// instantiation ahead of time.
+
+namespace without_dependent_base {
+template<class T>
+struct A {
+  void f(A& other) {
+    A::x; // { dg-error "'x' is not a member" }
+    this->x; // { dg-error "no member named 'x'" }
+    other.y; // { dg-error "no member named 'y'" }
+    typename A::type z; // { dg-error "does not name a type" }
+
+    struct B {
+      void g(A& other) {
+	A::x; // { dg-error "'x' is not a member" }
+	this->x; // { dg-error "no member named 'x'" }
+	other.y; // { dg-error "no member named 'y'" }
+	typename A::type z; // { dg-error "does not name a type" }
+      }
+    };
+  }
+};
+}
+
+namespace with_dependent_base {
+template<class T>
+struct A : T {
+  void f(A& other) {
+    A::x;
+    this->x;
+    other.y;
+    typename A::type z;
+
+    struct B : T {
+      void g(A& other) {
+	A::x;
+	this->x;
+	other.y;
+	typename A::type z;
+      }
+    };
+  }
+};
+}
diff --git a/gcc/testsuite/g++.dg/template/static30.C b/gcc/testsuite/g++.dg/template/static30.C
index 07dafe2..248f9e9 100644
--- a/gcc/testsuite/g++.dg/template/static30.C
+++ b/gcc/testsuite/g++.dg/template/static30.C
@@ -6,5 +6,5 @@ template <int> struct A
   static const int i2;
 };
 
-template <int N> const int A<N>::i1(A<N>::i);
-template <int N> const int A<N>::i2(3, A<N>::i); // { dg-error "expression list" }
+template <int N> const int A<N>::i1(A<N>::i1);
+template <int N> const int A<N>::i2(3, A<N>::i2); // { dg-error "expression list" }
diff --git a/gcc/testsuite/g++.old-deja/g++.other/decl5.C b/gcc/testsuite/g++.old-deja/g++.other/decl5.C
index 26556aa..c24957f 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/decl5.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/decl5.C
@@ -18,7 +18,7 @@ struct A {
   struct Z;
   expand me;          // { dg-error "'expand' does not name a type" }
   void foo(struct A::e);
-  void foo(struct A::z);  // { dg-error "incomplete" }
+  void foo(struct A::z);  // { dg-error "does not name a type" }
 };
 
 struct Q;
diff --git a/libstdc++-v3/include/experimental/socket b/libstdc++-v3/include/experimental/socket
index 02c27d6..3fe83a0 100644
--- a/libstdc++-v3/include/experimental/socket
+++ b/libstdc++-v3/include/experimental/socket
@@ -2450,7 +2450,7 @@ inline namespace v1
 	// XXX ???     ^^^^^^^
       {
 	// XXX ??? this->init(std::addressof(_M_sb));
-	this->set_rbduf(std::addressof(_M_sb));
+	this->set_rdbuf(std::addressof(_M_sb));
       }
 
       template<typename... _Args>
diff --git a/libstdc++-v3/include/tr2/dynamic_bitset b/libstdc++-v3/include/tr2/dynamic_bitset
index 274c4f6..f0878d7 100644
--- a/libstdc++-v3/include/tr2/dynamic_bitset
+++ b/libstdc++-v3/include/tr2/dynamic_bitset
@@ -304,7 +304,7 @@ namespace tr2
       bool
       _M_is_proper_subset_of(const __dynamic_bitset_base& __b) const noexcept
       {
-	if (this->is_subset_of(__b))
+	if (this->_M_is_subset_of(__b))
 	  {
 	    if (*this == __b)
 	      return false;