b9db89fbcf
Replace references to `enumerate` results with either const lvalue rerences or structured bindings. I did not use structured bindings everywhere as it wasn't clear to me it would improve readability. This is in preparation to the switch to `zip` semantics which won't support non-const lvalue reference to elements: https://reviews.llvm.org/D144503. Reviewed By: dblaikie Differential Revision: https://reviews.llvm.org/D145987