error[E0308]: mismatched types
  --> $DIR/pptypedef.rs:4:37
   |
LL |     let_in(3u32, |i| { assert!(i == 3i32); });
   |                                     ^^^^ expected u32, found i32

error[E0308]: mismatched types
  --> $DIR/pptypedef.rs:8:37
   |
LL |     let_in(3i32, |i| { assert!(i == 3u32); });
   |                                     ^^^^ expected i32, found u32

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0308`.