error[E0308]: mismatched types
  --> $DIR/equality.rs:15:5
   |
LL | fn two(x: bool) -> impl Foo {
   |                    -------- expected because this return type...
LL |     if x {
LL |         return 1_i32;
   |                ----- ...is found to be `i32` here
LL |     }
LL |     0_u32
   |     ^^^^^ expected `i32`, found `u32`

error[E0277]: cannot add `impl Foo` to `u32`
  --> $DIR/equality.rs:24:11
   |
LL |         n + sum_to(n - 1)
   |           ^ no implementation for `u32 + impl Foo`
   |
   = help: the trait `std::ops::Add<impl Foo>` is not implemented for `u32`

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0277, E0308.
For more information about an error, try `rustc --explain E0277`.