[libcxx-commits] [libcxx] [libc++] Correct `optional<T&>` implementation (PR #174537)

[William Tran-Viet via libcxx-commits]

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@@ -496,29 +491,33 @@ struct __optional_storage_base<_Tp, true> {
 
   _LIBCPP_HIDE_FROM_ABI constexpr __optional_storage_base() noexcept : __value_(nullptr) {}
 
+  template <class _Up>
+  _LIBCPP_HIDE_FROM_ABI constexpr void __convert_init_ref_val(_Up&& __val) {
+    _Tp& __r(std::forward<_Up>(__val));
+    __value_ = std::addressof(__r);
+  }
+
   template <class _UArg>
-  _LIBCPP_HIDE_FROM_ABI constexpr explicit __optional_storage_base(in_place_t, _UArg&& __uarg)
-      : __value_(std::addressof(__uarg)) {
+  _LIBCPP_HIDE_FROM_ABI constexpr explicit __optional_storage_base(in_place_t, _UArg&& __uarg) {
     static_assert(!__reference_constructs_from_temporary_v<_Tp, _UArg>,
                   "Attempted to construct a reference element in optional from a "
                   "possible temporary");
+    __convert_init_ref_val(__uarg);
   }
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void reset() noexcept { __value_ = nullptr; }
 
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool has_value() const noexcept { return __value_ != nullptr; }
 
-  _LIBCPP_HIDE_FROM_ABI constexpr value_type& __get() const& noexcept { return *__value_; }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr value_type&& __get() const&& noexcept { return std::forward<value_type>(*__value_); }
+  _LIBCPP_HIDE_FROM_ABI constexpr value_type& __get() const noexcept { return *__value_; }
 
   template <class _UArg>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __construct(_UArg&& __val) {
     _LIBCPP_ASSERT_INTERNAL(!has_value(), "__construct called for engaged __optional_storage");
     static_assert(!__reference_constructs_from_temporary_v<_Tp, _UArg>,
                   "Attempted to construct a reference element in tuple from a "
                   "possible temporary");
-    __value_ = std::addressof(__val);
+    __convert_init_ref_val(__val);
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smallp-o-p wrote:

Hm, maybe it would be simpler to review if I broke out the `optional<T&>` tests into their own directory...

https://github.com/llvm/llvm-project/pull/174537