diff --git a/gcc/objc/ChangeLog b/gcc/objc/ChangeLog
index 562081b9876..b717a946d05 100644
--- a/gcc/objc/ChangeLog
+++ b/gcc/objc/ChangeLog
@@ -1,3 +1,11 @@
+2010-12-30  Nicola Pero  <nicola@nicola.brainstorm.co.uk>
+
+	* objc-act.c (start_class): Warn when a class attribute is
+	ignored.
+	(objc_declare_protocols): Warn when a protocol attribute in a
+	protocol forward-declaration is ignored.
+	(start_protocol): Warn when a protocol attribute is ignored.
+
 2010-12-30  Nicola Pero  <nicola.pero@meta-innovation.com>
 
 	* objc-act.c (objc_set_method_opt): Tidy up error messages.  In
diff --git a/gcc/objc/objc-act.c b/gcc/objc/objc-act.c
index bc959d6060b..a0a7a095eb4 100644
--- a/gcc/objc/objc-act.c
+++ b/gcc/objc/objc-act.c
@@ -9722,6 +9722,8 @@ start_class (enum tree_code code, tree class_name, tree super_name,
 	      
 	      if (is_attribute_p  ("deprecated", name))
 		TREE_DEPRECATED (klass) = 1;
+	      else
+		warning (OPT_Wattributes, "%qE attribute directive ignored", name);
 	    }
 	  TYPE_ATTRIBUTES (klass) = attributes;
 	}
@@ -10924,6 +10926,8 @@ objc_declare_protocols (tree names, tree attributes)
 	  
 	  if (is_attribute_p  ("deprecated", name))
 	    deprecated = true;
+	  else
+	    warning (OPT_Wattributes, "%qE attribute directive ignored", name);
 	}
     }
 
@@ -10977,6 +10981,8 @@ start_protocol (enum tree_code code, tree name, tree list, tree attributes)
 	  
 	  if (is_attribute_p  ("deprecated", name))
 	    deprecated = true;
+	  else
+	    warning (OPT_Wattributes, "%qE attribute directive ignored", name);
 	}
     }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 43b5afb6c39..7dd36f1b9b0 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2010-12-30  Nicola Pero  <nicola.pero@meta-innovation.com>
+
+	* objc.dg/attributes/class-attribute-3.m: New.
+	* objc.dg/attributes/proto-attribute-4.m: New.
+	* obj-c++.dg/attributes/class-attribute-3.mm: New.
+	* obj-c++.dg/attributes/proto-attribute-4.mm: New.	
+	
 2010-12-30  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/47060
diff --git a/gcc/testsuite/obj-c++.dg/attributes/class-attribute-3.mm b/gcc/testsuite/obj-c++.dg/attributes/class-attribute-3.mm
new file mode 100644
index 00000000000..f96500de4dc
--- /dev/null
+++ b/gcc/testsuite/obj-c++.dg/attributes/class-attribute-3.mm
@@ -0,0 +1,14 @@
+/* Contributed by Nicola Pero <nicola.pero@meta-innovation.com>, December 2010.  */
+/* { dg-do compile } */
+
+/* Test that you get a warning when an unknown class attribute is ignored.  */
+
+#include <objc/objc.h>
+
+__attribute__ ((unknown_attribute))
+@interface MyClass /* { dg-warning "ignored" } */
+{
+  Class isa;
+}
++ (id) new;
+@end
diff --git a/gcc/testsuite/obj-c++.dg/attributes/proto-attribute-4.mm b/gcc/testsuite/obj-c++.dg/attributes/proto-attribute-4.mm
new file mode 100644
index 00000000000..d2e5f28a1b4
--- /dev/null
+++ b/gcc/testsuite/obj-c++.dg/attributes/proto-attribute-4.mm
@@ -0,0 +1,31 @@
+/* Contributed by Nicola Pero <nicola.pero@meta-innovation.com>, December 2010.  */
+/* { dg-do compile } */
+
+/* Test that you get a warning when an unknown protocol attribute is ignored.  */
+
+#include <objc/objc.h>
+
+__attribute__ ((unknown_attribute))
+@protocol MyProtocol /* { dg-warning "ignored" } */
+- (id) new;
+@end
+
+__attribute__ ((unknown_attribute))
+@protocol MyProtocol2; /* { dg-warning "ignored" } */
+
+/* Use the protocols to double-check that no more warnings are
+   generated.  */
+
+@interface MyClass <MyProtocol>
+@end
+
+int test (id <MyProtocol2> x)
+{
+  if (@protocol (MyProtocol) == @protocol (MyProtocol2))
+    return 1;
+
+  if (x)
+    return 2;
+
+  return 3;
+}
diff --git a/gcc/testsuite/objc.dg/attributes/class-attribute-3.m b/gcc/testsuite/objc.dg/attributes/class-attribute-3.m
new file mode 100644
index 00000000000..6cc5d4e2681
--- /dev/null
+++ b/gcc/testsuite/objc.dg/attributes/class-attribute-3.m
@@ -0,0 +1,14 @@
+/* Contributed by Nicola Pero <nicola.pero@meta-innovation.com>, December 2010.  */
+/* { dg-do compile } */
+
+/* Test that you get a warning when an unknown class attribute is ignored.  */
+
+#include <objc/objc.h>
+
+__attribute__ ((unknown_attribute))
+@interface MyClass
+{ /* { dg-warning "ignored" } */
+  Class isa;
+}
++ (id) new;
+@end
diff --git a/gcc/testsuite/objc.dg/attributes/proto-attribute-4.m b/gcc/testsuite/objc.dg/attributes/proto-attribute-4.m
new file mode 100644
index 00000000000..226fd68b3f2
--- /dev/null
+++ b/gcc/testsuite/objc.dg/attributes/proto-attribute-4.m
@@ -0,0 +1,31 @@
+/* Contributed by Nicola Pero <nicola.pero@meta-innovation.com>, December 2010.  */
+/* { dg-do compile } */
+
+/* Test that you get a warning when an unknown protocol attribute is ignored.  */
+
+#include <objc/objc.h>
+
+__attribute__ ((unknown_attribute))
+@protocol MyProtocol
+- (id) new; /* { dg-warning "ignored" } */
+@end
+
+__attribute__ ((unknown_attribute))
+@protocol MyProtocol2; /* { dg-warning "ignored" } */
+
+/* Use the protocols to double-check that no more warnings are
+   generated.  */
+
+@interface MyClass <MyProtocol>
+@end
+
+int test (id <MyProtocol2> x)
+{
+  if (@protocol (MyProtocol) == @protocol (MyProtocol2))
+    return 1;
+
+  if (x)
+    return 2;
+
+  return 3;
+}