[pushed] c++: improve lookup of member-qualified names

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 8df18c38d43..1fcd50c64fd 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7263,6 +7263,7 @@  extern tree maybe_get_template_decl_from_type_decl (tree);
 extern int processing_template_parmlist;
 extern bool dependent_type_p			(tree);
 extern bool dependent_scope_p			(tree);
+extern bool dependentish_scope_p		(tree);
 extern bool any_dependent_template_arguments_p  (const_tree);
 extern bool any_erroneous_template_args_p       (const_tree);
 extern bool dependent_template_p		(tree);
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 20f949edfe0..31bae6d8983 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -18187,6 +18187,16 @@  cp_parser_template_id (cp_parser *parser,
       if (TREE_CODE (template_id) == TEMPLATE_ID_EXPR)
 	SET_EXPR_LOCATION (template_id, combined_loc);
     }
+  else if (TREE_CODE (templ) == TYPE_DECL
+	   && TREE_CODE (TREE_TYPE (templ)) == TYPENAME_TYPE)
+    {
+      /* Some type template in dependent scope.  */
+      tree &name = TYPENAME_TYPE_FULLNAME (TREE_TYPE (templ));
+      name = build_min_nt_loc (combined_loc,
+			       TEMPLATE_ID_EXPR,
+			       name, arguments);
+      template_id = templ;
+    }
   else
     {
       /* If it's not a class-template or a template-template, it should be
@@ -18413,8 +18423,8 @@  cp_parser_template_name (cp_parser* parser,
     }
 
   /* cp_parser_lookup_name clears OBJECT_TYPE.  */
-  const bool scoped_p = ((parser->scope ? parser->scope
-			  : parser->context->object_type) != NULL_TREE);
+  tree scope = (parser->scope ? parser->scope
+		: parser->context->object_type);
 
   /* Look up the name.  */
   decl = cp_parser_lookup_name (parser, identifier,
@@ -18427,6 +18437,19 @@  cp_parser_template_name (cp_parser* parser,
 
   decl = strip_using_decl (decl);
 
+  /* 13.3 [temp.names] A < is interpreted as the delimiter of a
+    template-argument-list if it follows a name that is not a
+    conversion-function-id and
+    - that follows the keyword template or a ~ after a nested-name-specifier or
+    in a class member access expression, or
+    - for which name lookup finds the injected-class-name of a class template
+    or finds any declaration of a template, or
+    - that is an unqualified name for which name lookup either finds one or
+    more functions or finds nothing, or
+    - that is a terminal name in a using-declarator (9.9), in a declarator-id
+    (9.3.4), or in a type-only context other than a nested-name-specifier
+    (13.8).  */
+
   /* If DECL is a template, then the name was a template-name.  */
   if (TREE_CODE (decl) == TEMPLATE_DECL)
     {
@@ -18454,11 +18477,7 @@  cp_parser_template_name (cp_parser* parser,
     }
   else
     {
-      /* The standard does not explicitly indicate whether a name that
-	 names a set of overloaded declarations, some of which are
-	 templates, is a template-name.  However, such a name should
-	 be a template-name; otherwise, there is no way to form a
-	 template-id for the overloaded templates.  */
+      /* Look through an overload set for any templates.  */
       bool found = false;
 
       for (lkp_iterator iter (MAYBE_BASELINK_FUNCTIONS (decl));
@@ -18466,34 +18485,41 @@  cp_parser_template_name (cp_parser* parser,
 	if (TREE_CODE (*iter) == TEMPLATE_DECL)
 	  found = true;
 
+      /* "an unqualified name for which name lookup either finds one or more
+	 functions or finds nothing".  */
       if (!found
 	  && (cxx_dialect > cxx17)
-	  && !scoped_p
+	  && !scope
 	  && cp_lexer_next_token_is (parser->lexer, CPP_LESS)
 	  && tag_type == none_type)
 	{
-	  /* [temp.names] says "A name is also considered to refer to a template
-	     if it is an unqualified-id followed by a < and name lookup finds
-	     either one or more functions or finds nothing."  */
-
 	  /* The "more functions" case.  Just use the OVERLOAD as normally.
 	     We don't use is_overloaded_fn here to avoid considering
 	     BASELINKs.  */
 	  if (TREE_CODE (decl) == OVERLOAD
 	      /* Name lookup found one function.  */
-	      || TREE_CODE (decl) == FUNCTION_DECL)
+	      || TREE_CODE (decl) == FUNCTION_DECL
+	      /* Name lookup found nothing.  */
+	      || decl == error_mark_node)
 	    found = true;
-	  /* Name lookup found nothing.  */
-	  else if (decl == error_mark_node)
-	    return identifier;
 	}
 
+      /* "in a type-only context" */
+      if (!found && scope
+	  && tag_type != none_type
+	  && dependentish_scope_p (scope)
+	  && cp_parser_nth_token_starts_template_argument_list_p (parser, 1))
+	found = true;
+
       if (!found)
 	{
 	  /* The name does not name a template.  */
 	  cp_parser_error (parser, "expected template-name");
 	  return error_mark_node;
 	}
+      else if (decl == error_mark_node)
+	/* Repeat the lookup at instantiation time.  */
+	decl = identifier;
     }
 
   return decl;
@@ -30373,6 +30399,17 @@  cp_parser_lookup_name (cp_parser *parser, tree name,
 			       consider class templates.  */
 			    : is_template ? LOOK_want::TYPE
 			    : prefer_type_arg (tag_type));
+
+      /* If we know we're looking for a type (e.g. A in p->A::x),
+	 mock up a typename.  */
+      if (!decl && object_type && tag_type != none_type
+	  && dependentish_scope_p (object_type))
+	{
+	  tree type = build_typename_type (object_type, name, name,
+					   typename_type);
+	  decl = TYPE_NAME (type);
+	}
+
       parser->object_scope = object_type;
       parser->qualifying_scope = NULL_TREE;
     }
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 12c8812d8b2..4d42899f28d 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -26970,6 +26970,15 @@  dependent_scope_p (tree scope)
 	  && !currently_open_class (scope));
 }
 
+/* True if we might find more declarations in SCOPE during instantiation than
+   we can when parsing the template.  */
+
+bool
+dependentish_scope_p (tree scope)
+{
+  return dependent_scope_p (scope) || any_dependent_bases_p (scope);
+}
+
 /* T is a SCOPE_REF.  Return whether it represents a non-static member of
    an unknown base of 'this' (and is therefore instantiation-dependent).  */
 
diff --git a/gcc/testsuite/g++.dg/cpp23/lookup2.C b/gcc/testsuite/g++.dg/cpp23/lookup2.C
new file mode 100644
index 00000000000..a16afbe2196
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/lookup2.C
@@ -0,0 +1,6 @@ 
+// DR 1835
+
+template <class T> void f(T t) { t.foo::bar(); }
+struct foo { void bar(); };
+struct baz : foo { };
+int main() { f(baz()); }
diff --git a/gcc/testsuite/g++.dg/template/dtor11.C b/gcc/testsuite/g++.dg/template/dtor11.C
new file mode 100644
index 00000000000..9bb58b41d47
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/dtor11.C
@@ -0,0 +1,22 @@ 
+template <class T>
+struct B
+{
+  void f(T *p)
+  {
+    p->template A<int>::~A<int>();
+    p->A::~A();
+    p->~A<int>();
+    p->~A();
+    p->~T();
+    p->T::~T();
+  }
+};
+
+template <class T>
+struct A
+{ };
+
+int main()
+{
+  B<A<int> >().f(0);
+}
diff --git a/gcc/testsuite/g++.dg/template/dtor5.C b/gcc/testsuite/g++.dg/template/dtor5.C
index 8fa4eeb6f06..d9a1c692a34 100644
--- a/gcc/testsuite/g++.dg/template/dtor5.C
+++ b/gcc/testsuite/g++.dg/template/dtor5.C
@@ -11,7 +11,7 @@  template <class T> void f(A<T> *ap) {
 } 
 
 template <class T> void g(A<T> *ap) {
-  ap->~B(); 			// { dg-error "destructor name" }
+  ap->~B(); 			// { dg-error "" }
 } 
 
 int main()