[libcxx-commits] [libcxx] [libc++][ranges] Mark LWG3664 as resolved (PR #210550)

[A. Jiang via libcxx-commits]

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@@ -86,11 +86,11 @@ struct __distance {
   }
 
   template <class _Ip, sized_sentinel_for<decay_t<_Ip>> _Sp>
-  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip&& __first, _Sp __last) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<decay_t<_Ip>> operator()(_Ip&& __first, _Sp __last) const {
     if constexpr (sized_sentinel_for<_Sp, __remove_cvref_t<_Ip>>) {
       return __last - __first;
     } else {
-      return __last - decay_t<_Ip>(__first);
+      return __last - static_cast<decay_t<_Ip>>(__first);
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frederick-vs-ja wrote:

As `decay_t<_Ip>` is an iterator type, `decay_t<_Ip>(__first)` is equivalent to `static_cast<decay_t<_Ip>>(__first)`, and we don't need to change this line. But it seems that we should change the return type of this `operator()`.

I think we should try to add a test case which fails without changing the return type.

https://github.com/llvm/llvm-project/pull/210550