--- gcc/c-family/c-common.h.jj	2019-11-15 09:28:56.904930082 +0100
+++ gcc/c-family/c-common.h	2019-11-22 12:47:45.261379415 +0100
@@ -811,6 +811,7 @@ extern void c_register_addr_space (const
 extern bool in_late_binary_op;
 extern const char *c_addr_space_name (addr_space_t as);
 extern tree identifier_global_value (tree);
+extern tree identifier_global_tag (tree);
 extern bool names_builtin_p (const char *);
 extern tree c_linkage_bindings (tree);
 extern void record_builtin_type (enum rid, const char *, tree);
--- gcc/c-family/c-format.c.jj	2019-11-19 22:26:45.842300595 +0100
+++ gcc/c-family/c-format.c	2019-11-22 13:12:12.765658215 +0100
@@ -4899,31 +4899,32 @@ init_dynamic_gfc_info (void)
     }
 }
 
-/* Lookup the type named NAME and return a pointer-to-NAME type if found.
-   Otherwise, return void_type_node if NAME has not been used yet, or NULL_TREE if
-   NAME is not a type (issuing an error).  */
+/* Lookup the type named NAME and return a NAME type if found.
+   Otherwise, return void_type_node if NAME has not been used yet,
+   or NULL_TREE if NAME is not a type (issuing an error).  */
 
 static tree
-get_pointer_to_named_type (const char *name)
+get_named_type (const char *name)
 {
-  tree result;
-  if ((result = maybe_get_identifier (name)))
+  if (tree result = maybe_get_identifier (name))
     {
-      result = identifier_global_value (result);
+      result = identifier_global_tag (result);
       if (result)
 	{
-	  if (TREE_CODE (result) != TYPE_DECL)
+	  if (TYPE_P (result))
+	    ;
+	  else if (TREE_CODE (result) == TYPE_DECL)
+	    result = TREE_TYPE (result);
+	  else
 	    {
 	      error ("%qs is not defined as a type", name);
 	      result = NULL_TREE;
 	    }
-	  else
-	    result = TREE_TYPE (result);
 	}
+      return result;
     }
   else
-    result = void_type_node;
-  return result;
+    return void_type_node;
 }
 
 /* Determine the types of "tree" and "location_t" in the code being
@@ -4953,23 +4954,24 @@ init_dynamic_diag_info (void)
 	 an extra type level.  */
       if ((local_tree_type_node = maybe_get_identifier ("tree")))
 	{
-	  local_tree_type_node = identifier_global_value (local_tree_type_node);
+	  local_tree_type_node
+	    = identifier_global_value (local_tree_type_node);
 	  if (local_tree_type_node)
 	    {
 	      if (TREE_CODE (local_tree_type_node) != TYPE_DECL)
 		{
 		  error ("%<tree%> is not defined as a type");
-		  local_tree_type_node = 0;
+		  local_tree_type_node = NULL_TREE;
 		}
 	      else if (TREE_CODE (TREE_TYPE (local_tree_type_node))
 		       != POINTER_TYPE)
 		{
 		  error ("%<tree%> is not defined as a pointer type");
-		  local_tree_type_node = 0;
+		  local_tree_type_node = NULL_TREE;
 		}
 	      else
-		local_tree_type_node =
-		  TREE_TYPE (TREE_TYPE (local_tree_type_node));
+		local_tree_type_node
+		  = TREE_TYPE (TREE_TYPE (local_tree_type_node));
 	    }
 	}
       else
@@ -4979,12 +4981,12 @@ init_dynamic_diag_info (void)
   /* Similar to the above but for gimple*.  */
   if (!local_gimple_ptr_node
       || local_gimple_ptr_node == void_type_node)
-    local_gimple_ptr_node = get_pointer_to_named_type ("gimple");
+    local_gimple_ptr_node = get_named_type ("gimple");
 
   /* Similar to the above but for cgraph_node*.  */
   if (!local_cgraph_node_ptr_node
       || local_cgraph_node_ptr_node == void_type_node)
-    local_cgraph_node_ptr_node = get_pointer_to_named_type ("cgraph_node");
+    local_cgraph_node_ptr_node = get_named_type ("cgraph_node");
 
   static tree hwi;
 
--- gcc/c/c-decl.c.jj	2019-11-20 09:24:25.793311423 +0100
+++ gcc/c/c-decl.c	2019-11-22 12:48:35.697598249 +0100
@@ -10168,6 +10168,20 @@ identifier_global_value	(tree t)
   return NULL_TREE;
 }
 
+/* Return the global value of tag T as a symbol.  */
+
+tree
+identifier_global_tag (tree t)
+{
+  struct c_binding *b;
+
+  for (b = I_TAG_BINDING (t); b; b = b->shadowed)
+    if (B_IN_FILE_SCOPE (b) || B_IN_EXTERNAL_SCOPE (b))
+      return b->decl;
+
+  return NULL_TREE;
+}
+
 /* Returns true if NAME refers to a built-in function or function-like
    operator.  */
 
--- gcc/cp/cp-objcp-common.c.jj	2019-11-22 11:51:28.090682190 +0100
+++ gcc/cp/cp-objcp-common.c	2019-11-22 12:51:44.500674052 +0100
@@ -349,6 +349,15 @@ identifier_global_value (tree name)
   return get_global_binding (name);
 }
 
+/* Similarly, but return struct/class/union NAME instead.  */
+
+tree
+identifier_global_tag (tree name)
+{
+  return lookup_qualified_name (global_namespace, name, /*prefer_type*/2,
+				/*complain*/false);
+}
+
 /* Returns true if NAME refers to a built-in function or function-like
    operator.  */
 
--- gcc/testsuite/c-c++-common/pr90677.c.jj	2019-11-22 12:40:14.835355655 +0100
+++ gcc/testsuite/c-c++-common/pr90677.c	2019-11-22 12:40:14.835355655 +0100
@@ -0,0 +1,11 @@
+/* PR c/90677 */
+/* { dg-do compile } */
+/* { dg-options "-W -Wall" } */
+
+struct cgraph_node;
+union tree_node;
+typedef union tree_node *tree;
+union gimple_statement_d;
+typedef union gimple_statement_d *gimple;
+struct cgraph_node *cgraph_node (tree);
+void foo (int, const char *, ...) __attribute__((__format__(__gcc_diag__, 2, 3)));
