fixup! [libc++][string] Remove potential non-trailing 0-length array

Author: serge-sans-paille

libcxx/include/string

@@ -750,22 +750,22 @@ struct __init_with_sentinel_tag {};
 
 #ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 template <class _CharT, size_t __min_cap, size_t _Padding = sizeof(_CharT) - 1>
-struct __short_impl {
+struct __short_layout_alternate {
   _CharT __data_[__min_cap];
   unsigned char __padding_[_Padding];
   unsigned char __size_    : 7;
   unsigned char __is_long_ : 1;
 };
 
 template <class _CharT, size_t __min_cap>
-struct __short_impl<_CharT, __min_cap, 0> {
+struct __short_layout_alternate<_CharT, __min_cap, 0> {
   _CharT __data_[__min_cap];
   unsigned char __size_    : 7;
   unsigned char __is_long_ : 1;
 };
 #else
 template <class _CharT, size_t __min_cap, size_t _Padding = sizeof(_CharT) - 1>
-struct __short_impl {
+struct __short_layout_classic {
   struct _LIBCPP_PACKED {
     unsigned char __is_long_ : 1;
     unsigned char __size_    : 7;
@@ -774,7 +774,7 @@ struct __short_impl {
   _CharT __data_[__min_cap];
 };
 template <class _CharT, size_t __min_cap>
-struct __short_impl<_CharT, __min_cap, 0> {
+struct __short_layout_classic<_CharT, __min_cap, 0> {
   struct _LIBCPP_PACKED {
     unsigned char __is_long_ : 1;
     unsigned char __size_    : 7;
@@ -929,7 +929,11 @@ private:
 
 #endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 
-  using __short = __short_impl<value_type, __min_cap>;
+#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
+  using __short = __short_layout_alternate<value_type, __min_cap>;
+#else
+  using __short = __short_layout_classic<value_type, __min_cap>;
+#endif
   static_assert(sizeof(__short) == (sizeof(value_type) * (__min_cap + 1)), "__short has an unexpected size.");
 
   union __rep {