[llvm] [libc++] Ensure that `std::expected` has no tail padding (PR #69673)

[Jan Kokemüller via llvm-commits]

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@@ -1552,8 +1570,56 @@ class expected<_Tp, _Err> {
     _LIBCPP_NO_UNIQUE_ADDRESS _ErrorType __unex_;
   };
 
-  _LIBCPP_NO_UNIQUE_ADDRESS __union_t<_Err> __union_;
-  bool __has_val_;
+  struct __expected_repr {
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jiixyj wrote:

done!

https://github.com/llvm/llvm-project/pull/69673