Unregister classes when deleting them.

Coverage checking of the test suite showed that objc_disposeClassPair
wasn't tested at all, which then led to discovering that it didn't
unregister the class.

Test/AllocatePair.m

@@ -31,6 +31,11 @@ int main()
 	e = objc_allocateClassPair(d, "E", 0);
 	objc_registerClassPair(e);
 	assert(loaded == 0);
+	assert(objc_getClass("C") == c);
+	assert(objc_getClass("D") == d);
+	assert(objc_getClass("E") == e);
+	objc_disposeClassPair(e);
+	assert(objc_getClass("E") == nil);
 
 	return 0;
 }

class.h

@@ -272,11 +272,18 @@ static inline BOOL objc_test_class_flag(struct objc_class *aClass,
 	return (aClass->info & (unsigned long)flag) == (unsigned long)flag;
 }
 
+
 /**
  * Adds a class to the class table.
  */
 void class_table_insert(Class class);
 
+/**
+ * Removes a class from the class table.  Must be called with the runtime lock
+ * held!
+ */
+void class_table_remove(Class cls);
+
 /**
  * Array of classes used for small objects.  Small objects are embedded in
  * their pointer.  In 32-bit mode, we have one small object class (typically

class_table.c

@@ -457,6 +457,12 @@ BOOL objc_registerSmallObjectClass_np(Class class, uintptr_t mask)
 	return YES;
 }
 
+PRIVATE void class_table_remove(Class cls)
+{
+	assert(objc_test_class_flag(cls, objc_class_flag_user_created));
+	class_table_internal_remove(class_table, (void*)cls->name);
+}
+
 
 ////////////////////////////////////////////////////////////////////////////////
 // Public API

runtime.c

@@ -719,6 +719,7 @@ void objc_disposeClassPair(Class cls)
 		LOCK_RUNTIME_FOR_SCOPE();
 		safe_remove_from_subclass_list(meta);
 		safe_remove_from_subclass_list(cls);
+		class_table_remove(cls);
 	}
 
 	// Free the method and ivar lists.