Ref<T> and &T have different lifetime requirements

[KiChjang]

This does not compile: https://is.gd/aNuNEg

This compiles: https://is.gd/lInFDJ

Found when trying to solve servo/servo#13418 (comment)

[bluss]

Ref has the drop-check rule because it has a destructor (Essentially issue #22321)

[KalitaAlexey]

Dear @bluss,
Is there any work in progress on it?

[memoryruins]

Triage: now compiles on 2018.
2015 errors:

error[E0597]: borrowed value does not live long enough
  --> src/main.rs:18:9
   |
18 |         Document { url: RefCell::new("hi".into()) }.url().clone()
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ temporary value does not live long enough
19 |     }
   |     - temporary value dropped here while still borrowed
   |
   = note: values in a scope are dropped in the opposite order they are created

rustc: 1.32.0

edit: removing fixed-by-nll tag as I am not certain how it affects drop glue. pointing this out in another triage thread.

[pnkfelix]

FYI @memoryruins The use of NLL should not affect the dynamic semantics, at least in terms of when values are dropped.

Therefore the use of NLL-fixed-by-NLL might remain appropriate here. I'm investigating now.

[matthewjasper]

Closing since the code now compiles on both editions on nightly