Document undefined sprite template behavior

2 files changed, 6 insertions, 0 deletions

diff --git a/gflib/sprite.c b/gflib/sprite.c
index 2e96acf2c..c7e3d09a3 100644
--- a/gflib/sprite.c
+++ b/gflib/sprite.c
@@ -878,12 +878,14 @@ void ResetAllSprites(void)
     ResetSprite(&gSprites[i]);
 }
 
+// UB: template pointer may point to freed temporary storage
 void FreeSpriteTiles(struct Sprite *sprite)
 {
     if (sprite->template->tileTag != 0xFFFF)
         FreeSpriteTilesByTag(sprite->template->tileTag);
 }
 
+// UB: template pointer may point to freed temporary storage
 void FreeSpritePalette(struct Sprite *sprite)
 {
     FreeSpritePaletteByTag(sprite->template->paletteTag);
diff --git a/gflib/sprite.h b/gflib/sprite.h
index 9753837fd..c9ba9585d 100644
--- a/gflib/sprite.h
+++ b/gflib/sprite.h
@@ -182,6 +182,10 @@ struct SpriteTemplate
     SpriteCallback callback;
 };
 
+// UB: template pointer is often used to point to temporary storage,
+// then later dereferenced after being freed. Usually this won't
+// be visible in-game, but this is (part of) what causes the item
+// icon palette to flicker when changing items in the bag.
 struct Sprite
 {
     /*0x00*/ struct OamData oam;