[libcxx-commits] [libcxx] [libc++] Fix UB in <expected> related to "has value" flag (#68552) (PR #68733)

[Jan Kokemüller via libcxx-commits]

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@@ -909,6 +878,14 @@ class expected {
         std::__expected_construct_unexpected_from_invoke_tag, _Func&& __f, _Args&&... __args)
         : __unex_(std::invoke(std::forward<_Func>(__f), std::forward<_Args>(__args)...)) {}
 
+    template <class _Union>
+    _LIBCPP_HIDE_FROM_ABI constexpr explicit __union_t(bool __has_val, _Union&& __other) {
+      if (__has_val)
+        std::construct_at(this, std::in_place, std::forward<_Union>(__other).__val_);
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jiixyj wrote:

done!

https://github.com/llvm/llvm-project/pull/68733