error: unreachable expression
  --> $DIR/expr_return.rs:10:26
   |
LL |     let x: () = {return {return {return;}}};
   |                          ^^^^^^^^------^^
   |                          |       |
   |                          |       any code following this expression is unreachable
   |                          unreachable expression
   |
note: the lint level is defined here
  --> $DIR/expr_return.rs:4:9
   |
LL | #![deny(unreachable_code)]
   |         ^^^^^^^^^^^^^^^^

error: aborting due to previous error