From 072a98ca9aea8bfea7edc65f0a4a230974362b96 Mon Sep 17 00:00:00 2001
From: Sierraffinity <sierra@domoreaweso.me>
Date: Sat, 25 Apr 2020 18:25:55 -0700
Subject: [PATCH] Document undefined sprite template behavior

---
 gflib/sprite.c | 2 ++
 gflib/sprite.h | 4 ++++
 src/mevent2.c  | 4 ++++
 3 files changed, 10 insertions(+)

diff --git a/gflib/sprite.c b/gflib/sprite.c
index 2e96acf2c7..c7e3d09a32 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 9753837fd7..c9ba9585d9 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;
diff --git a/src/mevent2.c b/src/mevent2.c
index 0bbaf6db82..2991ac27ca 100755
--- a/src/mevent2.c
+++ b/src/mevent2.c
@@ -484,9 +484,13 @@ static void sub_801B7D8(u32 command)
         }
 
         if (dest == NULL)
+        {
             AGB_ASSERT(0);
+        }
         else if (++(*dest) > 999)
+        {
             *dest = 999;
+        }
     }
 }