[PATCH] D23252: [ADT] Extra STLExtras

[David Blaikie via llvm-commits]

dblaikie added inline comments.

================
Comment at: include/llvm/ADT/STLExtras.h:301
@@ +300,3 @@
+  typedef typename NatList<sizeof...(Args)>::eval nat_list;
+  std::tuple<Args...> ts;
+
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This keeps a copy (or move) of all its arguments to allow for the rvalue case in a range-for loop? That would have surprising performance characteristics (implicit whole-container copies) for non-temporary parameters... 

I think that gets into some pretty major design questions about the behavior here - and the major design problem/question with range proposals in general.

We might need to have a broader discussion about the design for anything like this - might be worth moving that part of the conversation to llvm-dev as I expect it'll be a bit more involved. But maybe here's OK & we can rope a few people in.




Repository:
  rL LLVM

https://reviews.llvm.org/D23252