Fix a bug in weak reference handling, where weak refers were being removed from

the table incorrectly, causing objects inserted at offsets due to hash
collisions to fail to be moved up and then fail to be found later.

Test by Eric Wasylishen!

Test/CMakeLists.txt

@@ -22,6 +22,7 @@ set(TESTS
 	ProtocolCreation.m
 	ResurrectInDealloc_arc.m
 	RuntimeTest.m
+	WeakReferences_arc.m
 	objc_msgSend.m
 	msgInterpose.m
 )

Test/WeakReferences_arc.m

@@ -0,0 +1,45 @@
+#include "Test.h"
+
+#define SIZE 5000
+
+int main(int argc, const char * argv[])
+{    
+	@autoreleasepool {
+		id __weak refs[SIZE];
+		id values[SIZE];
+
+		// Setup
+		for (int i=0; i<SIZE; i++)
+		{
+			values[i] = [Test new];
+			refs[i] = values[i];	
+		}
+
+		// Sanity check
+		for (int i=0; i<SIZE; i++)
+		{
+			assert(refs[i] != nil);
+			assert(refs[i] == values[i]);
+		}
+
+		// Release the value, one by one
+		for (int indexToRelease=0; indexToRelease<SIZE; indexToRelease++)
+		{
+			values[indexToRelease] = nil;
+			// Check all refs
+			for (int i=0; i<SIZE; i++)
+			{
+				if (i <= indexToRelease)
+				{
+					assert(refs[i] == nil);
+				}
+				else
+				{
+					assert(refs[i] != nil);
+					assert(refs[i] == values[i]);
+				}
+			}
+		}
+	}
+	return 0;
+}

arc.m

@@ -632,10 +632,6 @@ static void zeroRefs(WeakRef *ref, BOOL shouldFree)
 	{
 		free(ref);
 	}
-	else
-	{
-		memset(ref, 0, sizeof(WeakRef));
-	}
 }
 
 void objc_delete_weak_refs(id obj)
@@ -645,6 +641,7 @@ void objc_delete_weak_refs(id obj)
 	if (0 != oldRef)
 	{
 		zeroRefs(oldRef, NO);
+		weak_ref_remove(weakRefs, obj);
 	}
 }