warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/equality.rs:1:12
   |
LL | #![feature(specialization)]
   |            ^^^^^^^^^^^^^^
   |
   = note: `#[warn(incomplete_features)]` on by default
   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
   = help: consider using `min_specialization` instead, which is more stable and complete

error[E0308]: mismatched types
  --> $DIR/equality.rs:15:5
   |
LL | fn two(x: bool) -> impl Foo {
   |                    -------- expected `i32` because of return type
...
LL |     0_u32
   |     ^^^^^ expected `i32`, found `u32`
   |
help: change the type of the numeric literal from `u32` to `i32`
   |
LL |     0_i32
   |       ~~~

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 `Add<impl Foo>` is not implemented for `u32`
   = help: the following other types implement trait `Add<Rhs>`:
             <&'a f32 as Add<f32>>
             <&'a f64 as Add<f64>>
             <&'a i128 as Add<i128>>
             <&'a i16 as Add<i16>>
             <&'a i32 as Add<i32>>
             <&'a i64 as Add<i64>>
             <&'a i8 as Add<i8>>
             <&'a isize as Add<isize>>
           and 48 others

error: aborting due to 2 previous errors; 1 warning emitted

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