Fix Alignment of Hashed Structs (#287)

* Fix alignment of ASImageNodeContentsKey struct to fix hashing

* Change the change log by logging a change

* Add the world's stupidest explicit cast

* Actually its simpler

CHANGELOG.md

@@ -24,4 +24,4 @@
 - [Layout] Extract layout implementation code into it's own subcategories [Michael Schneider] (https://github.com/maicki)[#272](https://github.com/TextureGroup/Texture/pull/272)
 - [Fix] Fix a potential crash when cell nodes that need layout are deleted during the same runloop.  [Adlai Holler](https://github.com/Adlai-Holler) [#279](https://github.com/TextureGroup/Texture/pull/279)
 - [Batch fetching] Add ASBatchFetchingDelegate that takes scroll velocity and remaining time into account [Huy Nguyen](https://github.com/nguyenhuy) [#281](https://github.com/TextureGroup/Texture/pull/281)
-
+- [Fix] Fix a major regression in our image node contents caching. [Adlai Holler](https://github.com/Adlai-Holler) [#287](https://github.com/TextureGroup/Texture/pull/287)

Source/ASImageNode.mm

@@ -113,15 +113,18 @@ typedef void (^ASImageNodeDrawParametersBlock)(ASWeakMapEntry *entry);
 
 - (NSUInteger)hash
 {
+#pragma clang diagnostic push
+#pragma clang diagnostic warning "-Wpadded"
   struct {
     NSUInteger imageHash;
     CGSize backingSize;
     CGRect imageDrawRect;
-    BOOL isOpaque;
+    NSInteger isOpaque;
     NSUInteger backgroundColorHash;
     void *willDisplayNodeContentWithRenderingContext;
     void *didDisplayNodeContentWithRenderingContext;
     void *imageModificationBlock;
+#pragma clang diagnostic pop
   } data = {
     _image.hash,
     _backingSize,

Source/ASTextNode.mm

@@ -64,9 +64,12 @@ static NSString *ASTextNodeTruncationTokenAttributeName = @"ASTextNodeTruncation
 
 - (NSUInteger)hash
 {
+#pragma clang diagnostic push
+#pragma clang diagnostic warning "-Wpadded"
   struct {
     size_t attributesHash;
     CGSize constrainedSize;
+#pragma clang diagnostic pop
   } data = {
     _attributes.hash(),
     _constrainedSize

Source/Private/ASHashing.h

@@ -34,6 +34,11 @@ ASDISPLAYNODE_EXTERN_C_BEGIN
  *    _bounds.size
  *  };
  *  return ASHashBytes(&data, sizeof(data));
+ *
+ * @warning: If a struct has padding, any fields that are intiailized in {} 
+ *   will have garbage data for their padding, which will break this hash! Either
+ *   use `pragma clang diagnostic warning "-Wpadded"` around your struct definition
+ *   or manually initialize the fields of your struct (`myStruct.x = 7;` etc).
  */
 NSUInteger ASHashBytes(void *bytes, size_t length);
 

Source/TextKit/ASTextKitAttributes.mm

@@ -24,6 +24,8 @@ NSString *const ASTextKitEntityAttributeName = @"ck_entity";
 
 size_t ASTextKitAttributes::hash() const
 {
+#pragma clang diagnostic push
+#pragma clang diagnostic warning "-Wpadded"
   struct {
     NSUInteger attrStringHash;
     NSUInteger truncationStringHash;
@@ -35,6 +37,7 @@ size_t ASTextKitAttributes::hash() const
     NSUInteger shadowColorHash;
     CGFloat shadowOpacity;
     CGFloat shadowRadius;
+#pragma clang diagnostic pop
   } data = {
     [attributedString hash],
     [truncationAttributedString hash],