[libcxx-commits] [libcxx] [libcxx] Remove empty ~__no_destroy (PR #89882)

[A. Jiang via libcxx-commits]

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@@ -29,33 +29,25 @@ struct __uninitialized_tag {};
 // initialization using __emplace.
 template <class _Tp>
 struct __no_destroy {
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI explicit __no_destroy(__uninitialized_tag) : __dummy_() {
-    if (__libcpp_is_constant_evaluated()) {
-      __dummy_ = char();
-    }
-  }
-  _LIBCPP_HIDE_FROM_ABI ~__no_destroy() {
-    // nothing
-  }
+  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI explicit __no_destroy(__uninitialized_tag) {}
 
   template <class... _Args>
-  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI explicit __no_destroy(_Args&&... __args)
-      : __obj_(std::forward<_Args>(__args)...) {}
+  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI explicit __no_destroy(_Args&&... __args) {
+    ::new ((void*)__obj_) _Tp(std::forward<_Args>(__args)...);
+  }
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frederick-vs-ja wrote:

The `constexpr` becomes meaningless after the current changes, even after [P2747](https://wg21.link/p2747) which will be adopted for C++26 soon. Note that the always-meaningless `constexpr` on a function makes the program ill-formed, no diagnostic required before C++23.

https://github.com/llvm/llvm-project/pull/89882