[llvm] [ADT] Add DenseSet::insert_range (PR #131567)

[Jakub Kuderski via llvm-commits]

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@@ -237,6 +238,10 @@ class DenseSetImpl {
     for (; I != E; ++I)
       insert(*I);
   }
+
+  template <typename Range> void insert_range(Range &&R) {
+    insert(adl_begin(R), adl_end(R));
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kuhar wrote:

Yeah, that's why I called it 'sad' -- nice to have but not really possible today

https://github.com/llvm/llvm-project/pull/131567