[libcxx-commits] [libcxx] [libc++] Make forward_list constexpr as part of P3372R3 (PR #129435)

[Peng Liu via libcxx-commits]

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@@ -302,6 +302,14 @@ concept __resettable_smart_pointer_with_args = requires(_Smart __s, _Pointer __p
 
 #endif
 
+template <class _PtrTo, class _PtrFrom>
+_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI _PtrTo __static_fancy_pointer_cast(const _PtrFrom& __p) {
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winner245 wrote:

The problem is that even without the cast to `__void_pointer`, the cast would fail in compile-time evaluation for fancy pointer (See: https://godbolt.org/z/E7jcezjnc). That's why I need `__static_fancy_pointer_cast`. 

https://github.com/llvm/llvm-project/pull/129435