Fix invoking missing superclass methods.

The lookup functions for the superclass paths were silently ignoring
missing methods, rather than calling the forwarding hook.

Fixes #153

Test/CMakeLists.txt

@@ -36,6 +36,7 @@ set(TESTS
 	ProtocolCreation.m
 	ResurrectInDealloc_arc.m
 	RuntimeTest.m
+	SuperMethodMissing.m
 	WeakBlock_arc.m
 	WeakRefLoad.m
 	WeakReferences_arc.m

Test/SuperMethodMissing.m

@@ -0,0 +1,46 @@
+#include "Test.h"
+#include "objc/hooks.h"
+#include <stdio.h>
+
+@interface Test (DoesNotExist)
+- (void)run;
+@end
+
+@interface Foo : Test
+@end
+
+@implementation Foo
+- (void)run
+{
+	[super run];
+}
+@end
+
+static int missing_methods;
+
+id forward(id self, SEL cmd, ...)
+{
+	Class cls = object_getClass(self);
+	missing_methods++;
+	fprintf(stderr, "Missing method:  %c[%s %s]\n", class_isMetaClass(cls) ? '+' : '-', class_getName(cls),sel_getName(cmd));
+	return nil;
+}
+
+IMP no_method(id self, SEL cmd)
+{
+	return forward;
+}
+
+
+int
+main()
+{
+	__objc_msg_forward2 = no_method;
+	Test *t = [Test new];
+	[t run];
+	assert(missing_methods == 1);
+	Foo *f = [Foo new];
+	[f run];
+	assert(missing_methods == 2);
+	//[Test run];
+}

sendmsg2.c

@@ -302,7 +302,8 @@ struct objc_slot2 *objc_slot_lookup_super2(struct objc_super *super, SEL selecto
 				objc_send_initialize((id)class);
 				return objc_slot_lookup_super2(super, selector);
 			}
-			return (struct objc_slot2*)&nil_slot;
+			uncacheable_slot.imp = __objc_msg_forward2(receiver, selector);
+			return (struct objc_slot2*)&uncacheable_slot;
 		}
 		return result;
 	}
@@ -335,7 +336,11 @@ struct objc_slot *objc_slot_lookup_super(struct objc_super *super, SEL selector)
 				objc_send_initialize((id)class);
 				return objc_slot_lookup_super(super, selector);
 			}
-			return &nil_slot_v1;
+			uncacheable_slot_v1.owner = Nil;
+			uncacheable_slot_v1.types = sel_getType_np(selector);
+			uncacheable_slot_v1.selector = selector;
+			uncacheable_slot_v1.method = __objc_msg_forward2(receiver, selector);
+			return &uncacheable_slot_v1;
 		}
 		uncacheable_slot_v1.owner = Nil;
 		uncacheable_slot_v1.types = sel_getType_np(((struct objc_method*)result)->selector);