[libcxx-commits] [libcxx] [libc++] Remove potential 0-sized array in __compressed_pair_padding (PR #109028)

[via libcxx-commits]

https://github.com/serge-sans-paille created https://github.com/llvm/llvm-project/pull/109028

None

>From 93a75f4f92fcf1ba54483fc91d6edf4d5c94ffc8 Mon Sep 17 00:00:00 2001
From: serge-sans-paille <sguelton at mozilla.com>
Date: Tue, 17 Sep 2024 20:39:05 +0200
Subject: [PATCH] [libc++] Remove potential 0-sized array in
 __compressed_pair_padding

---
 libcxx/include/__memory/compressed_pair.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/libcxx/include/__memory/compressed_pair.h b/libcxx/include/__memory/compressed_pair.h
index 629e3ad8848ffa..cc56912f5e34c5 100644
--- a/libcxx/include/__memory/compressed_pair.h
+++ b/libcxx/include/__memory/compressed_pair.h
@@ -52,13 +52,15 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 #ifndef _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING
 
-template <class _ToPad>
+template <class _ToPad,
+          bool _Empty = ((is_empty<_ToPad>::value && !__libcpp_is_final<_ToPad>::value) || is_reference<_ToPad>::value)>
 class __compressed_pair_padding {
-  char __padding_[((is_empty<_ToPad>::value && !__libcpp_is_final<_ToPad>::value) || is_reference<_ToPad>::value)
-                      ? 0
-                      : sizeof(_ToPad) - __datasizeof_v<_ToPad>];
+  char __padding_[sizeof(_ToPad) - __datasizeof_v<_ToPad>];
 };
 
+template <class _ToPad>
+class __compressed_pair_padding<_ToPad, true> {};
+
 #  define _LIBCPP_COMPRESSED_PAIR(T1, Initializer1, T2, Initializer2)                                                  \
     _LIBCPP_NO_UNIQUE_ADDRESS __attribute__((__aligned__(_LIBCPP_ALIGNOF(T2)))) T1 Initializer1;                       \
     _LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T1> _LIBCPP_CONCAT3(__padding1_, __LINE__, _);          \