error[E0046]: not all trait items implemented, missing: `Assoc`
  --> $DIR/best-obligation-ICE.rs:10:1
   |
LL |     type Assoc;
   |     ---------- `Assoc` from trait
...
LL | impl<T> Trait for W<W<W<T>>> {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `Assoc` in implementation

error[E0277]: the trait bound `W<W<T>>: Trait` is not satisfied
  --> $DIR/best-obligation-ICE.rs:10:19
   |
LL | impl<T> Trait for W<W<W<T>>> {}
   |                   ^^^^^^^^^^ unsatisfied trait bound
   |
help: the trait `Trait` is not implemented for `W<W<T>>`
  --> $DIR/best-obligation-ICE.rs:9:1
   |
LL | struct W<T: Trait>(*mut T);
   | ^^^^^^^^^^^^^^^^^^
note: required by a bound in `W`
  --> $DIR/best-obligation-ICE.rs:9:13
   |
LL | struct W<T: Trait>(*mut T);
   |             ^^^^^ required by this bound in `W`
help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
   |
LL | impl<T> Trait for W<W<W<T>>> where W<W<T>>: Trait {}
   |                              ++++++++++++++++++++

error[E0277]: the trait bound `W<T>: Trait` is not satisfied
  --> $DIR/best-obligation-ICE.rs:10:19
   |
LL | impl<T> Trait for W<W<W<T>>> {}
   |                   ^^^^^^^^^^ unsatisfied trait bound
   |
help: the trait `Trait` is not implemented for `W<T>`
  --> $DIR/best-obligation-ICE.rs:9:1
   |
LL | struct W<T: Trait>(*mut T);
   | ^^^^^^^^^^^^^^^^^^
note: required by a bound in `W`
  --> $DIR/best-obligation-ICE.rs:9:13
   |
LL | struct W<T: Trait>(*mut T);
   |             ^^^^^ required by this bound in `W`
help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
   |
LL | impl<T> Trait for W<W<W<T>>> where W<T>: Trait {}
   |                              +++++++++++++++++

error[E0277]: the trait bound `T: Trait` is not satisfied
  --> $DIR/best-obligation-ICE.rs:10:19
   |
LL | impl<T> Trait for W<W<W<T>>> {}
   |                   ^^^^^^^^^^ the trait `Trait` is not implemented for `T`
   |
note: required by a bound in `W`
  --> $DIR/best-obligation-ICE.rs:9:13
   |
LL | struct W<T: Trait>(*mut T);
   |             ^^^^^ required by this bound in `W`
help: consider restricting type parameter `T` with trait `Trait`
   |
LL | impl<T: Trait> Trait for W<W<W<T>>> {}
   |       +++++++

error[E0119]: conflicting implementations of trait `NoOverlap` for type `W<W<W<W<_>>>>`
  --> $DIR/best-obligation-ICE.rs:18:1
   |
LL | impl<T: Trait> NoOverlap for T {}
   | ------------------------------ first implementation here
LL | impl<T: Trait<Assoc = u32>> NoOverlap for W<T> {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `W<W<W<W<_>>>>`

error: aborting due to 5 previous errors

Some errors have detailed explanations: E0046, E0119, E0277.
For more information about an error, try `rustc --explain E0046`.