[libcxx-commits] [libcxx] [libc++][NFC] Refactor __libcpp_datasizeof to be a variable template (PR #87769)

[via libcxx-commits]

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@@ -26,39 +26,38 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <class _Tp>
-struct __libcpp_datasizeof {
 #if __has_extension(datasizeof)
-  static const size_t value = __datasizeof(_Tp);
+template <class _Tp>
+inline const size_t __datasizeof_v = __datasizeof(_Tp);
 #else
 // NOLINTNEXTLINE(readability-redundant-preprocessor) This is https://llvm.org/PR64825
 #  if __has_cpp_attribute(__no_unique_address__)
-  template <class = char>
-  struct _FirstPaddingByte {
-    [[__no_unique_address__]] _Tp __v_;
-    char __first_padding_byte_;
-  };
+template <class _Tp>
+struct _FirstPaddingByte {
+  [[__no_unique_address__]] _Tp __v_;
+  char __first_padding_byte_;
+};
 #  else
-  template <bool = __libcpp_is_final<_Tp>::value || !is_class<_Tp>::value>
-  struct _FirstPaddingByte : _Tp {
-    char __first_padding_byte_;
-  };
+template <class _Tp, bool = __libcpp_is_final<_Tp>::value || !is_class<_Tp>::value>
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EricWF wrote:

This adds more template parameters, which means larger names, do we need this?

https://github.com/llvm/llvm-project/pull/87769