[libcxx-commits] [libcxx] [libc++] Implement P2988R12: `std::optional<T&> (PR #155202)

[A. Jiang via libcxx-commits]

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@@ -919,20 +937,38 @@ public:
     return std::move(this->__get());
   }
 
-  template <class _Up>
+  template <class _Up = remove_cv_t<_Tp>>
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frederick-vs-ja wrote:

The default template arguments are added via [LWG3886](https://cplusplus.github.io/LWG/issue3886). Would you mind to implement the whole resolution of LWG3886 (which also modifies `expected`) first?

https://github.com/llvm/llvm-project/pull/155202