[libcxx-commits] [libcxx] [libc++][mdspan] P3383R3: mdspan.at() (PR #175213)

[Nikolas Klauser via libcxx-commits]

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@@ -213,6 +214,37 @@ class mdspan {
     }(make_index_sequence<rank()>()));
   }
 
+#  if _LIBCPP_STD_VER >= 26
+  template <class... _OtherIndexTypes>
+    requires((is_convertible_v<_OtherIndexTypes, index_type> && ...) &&
+             (is_nothrow_constructible_v<index_type, _OtherIndexTypes> && ...) &&
+             (sizeof...(_OtherIndexTypes) == rank()))
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr reference at(_OtherIndexTypes... __indices) const {
+    if (!__mdspan_detail::__is_multidimensional_index_in(__map_.extents(), __indices...)) {
+      __throw_out_of_range();
+    }
+    return operator[](static_cast<index_type>(std::move(__indices))...);
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philnik777 wrote:

```suggestion
    return (*this)[static_cast<index_type>(std::move(__indices))...];
```

https://github.com/llvm/llvm-project/pull/175213