So, I want to see if a type needs drop in
closure_analyze. Will calling
ty.needs_drop work reliably at that point?
Secondarily, it seems I need to lift the type to before using
needs_drop like that, a la https://github.com/rust-lang/rust/blob/e4e032a0ae82d7db4f99872ff98626af2941c4a5/src/librustc_mir/hair/cx/mod.rs#L190 -- is it valid to use the global context at this point though?