From 91c60802e646ee10daa8eda0ab2d2ea06206cc41 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Mon, 18 Jul 2022 22:24:28 -0600
Subject: [PATCH] [open-type] Fix overflow check

Without the cast, the compiler is within its rights to reason that
overflow didn't happen and optimize away the check, as clang was.
---
 src/hb-open-type.hh | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/hb-open-type.hh b/src/hb-open-type.hh
index bc43de7c3..d0d01a68c 100644
--- a/src/hb-open-type.hh
+++ b/src/hb-open-type.hh
@@ -458,7 +458,7 @@ struct UnsizedArrayOf
   {
     unsigned int i = (unsigned int) i_;
     const Type *p = &arrayZ[i];
-    if (unlikely (p < arrayZ)) return Null (Type); /* Overflowed. */
+    if (unlikely ((const void *) p < (const void *) arrayZ)) return Null (Type); /* Overflowed. */
     _hb_compiler_memory_r_barrier ();
     return *p;
   }
@@ -466,7 +466,7 @@ struct UnsizedArrayOf
   {
     unsigned int i = (unsigned int) i_;
     Type *p = &arrayZ[i];
-    if (unlikely (p < arrayZ)) return Crap (Type); /* Overflowed. */
+    if (unlikely ((const void *) p < (const void *) arrayZ)) return Crap (Type); /* Overflowed. */
     _hb_compiler_memory_r_barrier ();
     return *p;
   }
@@ -560,7 +560,7 @@ struct UnsizedListOfOffset16To : UnsizedArray16OfOffsetTo<Type, OffsetType, has_
   {
     unsigned int i = (unsigned int) i_;
     const OffsetTo<Type, OffsetType, has_null> *p = &this->arrayZ[i];
-    if (unlikely (p < this->arrayZ)) return Null (Type); /* Overflowed. */
+    if (unlikely ((const void *) p < (const void *) this->arrayZ)) return Null (Type); /* Overflowed. */
     _hb_compiler_memory_r_barrier ();
     return this+*p;
   }
@@ -568,7 +568,7 @@ struct UnsizedListOfOffset16To : UnsizedArray16OfOffsetTo<Type, OffsetType, has_
   {
     unsigned int i = (unsigned int) i_;
     const OffsetTo<Type, OffsetType, has_null> *p = &this->arrayZ[i];
-    if (unlikely (p < this->arrayZ)) return Crap (Type); /* Overflowed. */
+    if (unlikely ((const void *) p < (const void *) this->arrayZ)) return Crap (Type); /* Overflowed. */
     _hb_compiler_memory_r_barrier ();
     return this+*p;
   }