[libcxx-commits] [libcxx] [libc++] P3168R2 Give std::optional Range Support (PR #146491)

[A. Jiang via libcxx-commits]

================
@@ -578,6 +600,71 @@ struct __is_std_optional : false_type {};
 template <class _Tp>
 struct __is_std_optional<optional<_Tp>> : true_type {};
 
+#    if _LIBCPP_STD_VER >= 26
+
+template <class _T>
+constexpr bool ranges::enable_view<optional<_T>> = true;
+
+template <class _T>
+constexpr auto format_kind<optional<_T>> = range_format::disabled;
+
+template <typename _Tp>
+class __optional_iterator {
+public:
+  using value_type        = _Tp;
+  using difference_type   = std::ptrdiff_t;
+  using pointer           = _Tp*;
+  using reference         = _Tp&;
+  using iterator_category = std::forward_iterator_tag;
----------------
frederick-vs-ja wrote:

This is wrong. This iterator type must be a contiguous access iterator.
```suggestion
  using iterator_category = random_access_iterator_tag;
  using iterator_concept  = contiguous_iterator_tag;
```

https://github.com/llvm/llvm-project/pull/146491