Fix arithmetic underflow

winner245 · winner245 · commit 12182438439d · 2024-12-19T20:01:08.000-05:00
diff --git a/libcxx/include/__vector/vector_bool.h b/libcxx/include/__vector/vector_bool.h
@@ -115,7 +115,7 @@ class _LIBCPP_TEMPLATE_VIS vector<bool, _Allocator> {
   }
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 static size_type
   __external_cap_to_internal(size_type __n) _NOEXCEPT {
-    return (__n - 1) / __bits_per_word + 1;
+    return (__n + __bits_per_word - 1) / __bits_per_word;
   }
 
 public:

Original file line number	Diff line number	Diff line change
`@@ -115,7 +115,7 @@ class _LIBCPP_TEMPLATE_VIS vector<bool, _Allocator> {`
`115`	`115`	`}`
`116`	`116`	`_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 static size_type`
`117`	`117`	`__external_cap_to_internal(size_type __n) _NOEXCEPT {`
`118`		`- return (__n - 1) / __bits_per_word + 1;`
	`118`	`+ return (__n + __bits_per_word - 1) / __bits_per_word;`
`119`	`119`	`}`
`120`	`120`
`121`	`121`	`public:`