Possible false positive with let_and_return

[jeffrey-xiao]

The following code works but returns a clippy lint error: https://play.rust-lang.org/?version=stable&mode=debug&edition=2015&gist=2417f60b483ac63fd3ffd90b66d6db16

warning: returning the result of a let binding from a block. Consider returning the expression directly.
 --> src/main.rs:7:5
  |
7 |     ret
  |     ^^^
  |
  = note: #[warn(clippy::let_and_return)] on by default
note: this expression can be directly returned
 --> src/main.rs:6:15
  |
6 |     let ret = foo.borrow().baz();
  |               ^^^^^^^^^^^^^^^^^^
  = help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#let_and_return

When using the suggestion of clippy to remove the let, it fails to compile: https://play.rust-lang.org/?version=stable&mode=debug&edition=2015&gist=285ab39429037278c362bbb6d7ffddf6

error[E0597]: `foo` does not live long enough
 --> src/main.rs:6:5
  |
6 |     foo.borrow().baz()
  |     ^^^ borrowed value does not live long enough
7 | }
  | - `foo` dropped here while still borrowed
  |
  = note: values in a scope are dropped in the opposite order they are created

error: aborting due to previous error

For more information about this error, try `rustc --explain E0597`.
error: Could not compile `playground`.

To learn more, run the command again with --verbose.

[jorpic]

Seems this is a duplicate of #2904

[flip1995]

Not exactly a duplicate of #2904, since this suggestion also errors with nll enabled, while #2904 works with nll