[llvm] [ArrayRef] Add constructor from iterator_range<U*> (NFC). (PR #137796)

[Florian Hahn via llvm-commits]

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@@ -149,6 +149,13 @@ namespace llvm {
                  * = nullptr)
         : Data(Vec.data()), Length(Vec.size()) {}
 
+    /// Construct an ArrayRef<T> from iterator_range<U*>. This uses SFINAE
+    /// to ensure that this is only used for iterator ranges over plain pointer
+    /// iterators.
+    template <typename U, typename = std::enable_if_t<std::is_same_v<U *, T *>>>
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fhahn wrote:

Yep, this should use `is_convertible` I think, to support creating `ArrayRef<const X>` from `iterator_range<X *>`, also added a test

https://github.com/llvm/llvm-project/pull/137796