[libcxx-commits] [libcxx] [libc++] Implement P3168R2: Give optional range support (PR #149441)

[Louis Dionne via libcxx-commits]

================
@@ -792,6 +829,18 @@ public:
     }
   }
 
+#    if _LIBCPP_STD_VER >= 26
+  // [optional.iterators], iterator support
+  _LIBCPP_HIDE_FROM_ABI constexpr iterator begin() noexcept { return iterator(std::addressof(this->__get())); }
+
+  _LIBCPP_HIDE_FROM_ABI constexpr const_iterator begin() const noexcept {
+    return const_iterator(std::addressof(this->__get()));
+  }
+
+  _LIBCPP_HIDE_FROM_ABI constexpr iterator end() noexcept { return begin() + this->has_value(); }
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ldionne wrote:

```suggestion
  _LIBCPP_HIDE_FROM_ABI constexpr iterator end() noexcept { return begin() + (this->has_value() ? 1 : 0); }
```

Both are equivalent, but using a `bool` as an integer is usually frowned upon. This is a suggestion, not a hard request.

https://github.com/llvm/llvm-project/pull/149441