clang fixes and fix memory leak

src/core.h

@@ -110,7 +110,7 @@
 #define B2_ARRAY_COUNT( A ) (int)( sizeof( A ) / sizeof( A[0] ) )
 
 // Used to prevent the compiler from warning about unused variables
-#define B2_UNUSED( ... ) (void)( __VA_ARGS__ )
+#define B2_UNUSED( ... ) (void)sizeof( ( __VA_ARGS__, 0 ) )
 
 // Use to validate definitions. Do not take my cookie.
 #define B2_SECRET_COOKIE 1152023

src/shape.c

@@ -501,6 +501,15 @@ b2ChainId b2CreateChain( b2BodyId bodyId, const b2ChainDef* def )
 	return id;
 }
 
+void b2FreeChainData(b2ChainShape* chain)
+{
+	b2Free( chain->shapeIndices, chain->count * sizeof( int ) );
+	chain->shapeIndices = NULL;
+
+	b2Free( chain->materials, chain->materialCount * sizeof( b2SurfaceMaterial ) );
+	chain->materials = NULL;
+}
+
 void b2DestroyChain( b2ChainId chainId )
 {
 	b2World* world = b2GetWorldLocked( chainId.world0 );
@@ -543,10 +552,7 @@ void b2DestroyChain( b2ChainId chainId )
 		b2DestroyShapeInternal( world, shape, body, wakeBodies );
 	}
 
-	b2Free( chain->shapeIndices, chain->count * sizeof( int ) );
-	chain->shapeIndices = NULL;
-
-	b2Free( chain->materials, chain->materialCount * sizeof( b2SurfaceMaterial ) );
+	b2FreeChainData( chain );
 
 	// Return chain to free list.
 	b2FreeId( &world->chainIdPool, chain->id );

src/shape.h

@@ -83,6 +83,8 @@ typedef struct
 void b2CreateShapeProxy( b2Shape* shape, b2BroadPhase* bp, b2BodyType type, b2Transform transform, bool forcePairCreation );
 void b2DestroyShapeProxy( b2Shape* shape, b2BroadPhase* bp );
 
+void b2FreeChainData( b2ChainShape* chain );
+
 b2MassData b2ComputeShapeMass( const b2Shape* shape );
 b2ShapeExtent b2ComputeShapeExtent( const b2Shape* shape, b2Vec2 localCenter );
 b2AABB b2ComputeShapeAABB( const b2Shape* shape, b2Transform transform );

src/world.c

@@ -296,11 +296,12 @@ void b2DestroyWorld( b2WorldId worldId )
 		b2ChainShape* chain = world->chainShapes.data + i;
 		if ( chain->id != B2_NULL_INDEX )
 		{
-			b2Free( chain->shapeIndices, chain->count * sizeof( int ) );
+			b2FreeChainData( chain );
 		}
 		else
 		{
 			B2_ASSERT( chain->shapeIndices == NULL );
+			B2_ASSERT( chain->materials == NULL );
 		}
 	}