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

[Ramkumar Ramachandra via llvm-commits]

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@@ -149,6 +149,19 @@ 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 of random access
+    /// iterators that can be converted.
+    template <typename U>
+    ArrayRef(const iterator_range<U *> &Range,
+             std::enable_if_t<std::is_base_of<std::random_access_iterator_tag,
+                                              typename std::iterator_traits<
+                                                  decltype(Range.begin())>::
+                                                  iterator_category>::value &&
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artagnon wrote:

Make this also a template parameter?

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