[libcxx-commits] [libcxx] [libc++] P2944R3: Constrained comparisions - `optional` (PR #144249)

[A. Jiang via libcxx-commits]

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@@ -30,6 +30,13 @@ template <class _Tp, class _Up>
 struct __is_core_convertible<_Tp, _Up, decltype(static_cast<void (*)(_Up)>(0)(static_cast<_Tp (*)()>(0)()))>
     : true_type {};
 
+#if _LIBCPP_STD_VER >= 17
+
+template <class _Tp>
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frederick-vs-ja wrote:

I think it's better to introduce `__is_core_convertible_v` first and implement `__is_core_convertible` with it, then use `__is_core_convertible_v<decltype(...), bool>` in the constraints.

https://github.com/llvm/llvm-project/pull/144249