tests/ui/traits/next-solver/cycles/forced_ambiguity-use-head-maybe-cause.stderr

error[E0283]: type annotations needed
  --> $DIR/forced_ambiguity-use-head-maybe-cause.rs:43:19
   |
LL |     impls_trait::<Root<_>>()
   |                   ^^^^^^^ cannot infer type for struct `Head<_>`
   |
   = note: cannot satisfy `Head<_>: Trait`
help: the following types implement trait `Trait`
  --> $DIR/forced_ambiguity-use-head-maybe-cause.rs:23:1
   |
LL | / impl<T> Trait for Head<T>
LL | | where
LL | |     Root<T>: Trait,
LL | |     T: Trait, // ambiguous
   | |_____________^ `Head<T>`
...
LL | / impl<T> Trait for Head<T>
LL | | where
LL | |     Error<T>: Trait,
LL | |     NotImplemented<T>: Trait,
   | |_____________________________^ `Head<T>`
note: required for `Root<_>` to implement `Trait`
  --> $DIR/forced_ambiguity-use-head-maybe-cause.rs:18:9
   |
LL | impl<T> Trait for Root<T>
   |         ^^^^^     ^^^^^^^
LL | where
LL |     Head<T>: Trait,
   |              ----- unsatisfied trait bound introduced here
   = note: 8 redundant requirements hidden
   = note: required for `Root<_>` to implement `Trait`
note: required by a bound in `impls_trait`
  --> $DIR/forced_ambiguity-use-head-maybe-cause.rs:41:19
   |
LL | fn impls_trait<T: Trait>() {}
   |                   ^^^^^ required by this bound in `impls_trait`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0283`.