error[E0277]: the trait bound `T: Unstable` is not satisfied
  --> $DIR/unstable-trait-suggestion.rs:13:9
   |
LL |     foo(t)
   |     --- ^ the trait `Unstable` is not implemented for `T`
   |     |
   |     required by a bound introduced by this call
   |
note: required by a bound in `foo`
  --> $DIR/unstable-trait-suggestion.rs:9:11
   |
LL | fn foo<T: Unstable>(_: T) {}
   |           ^^^^^^^^ required by this bound in `foo`
help: consider restricting type parameter `T` with unstable trait `Unstable`
   |
LL | pub fn bar<T: Unstable>(t: T) {
   |             ++++++++++

error[E0277]: the trait bound `T: Step` is not satisfied
  --> $DIR/unstable-trait-suggestion.rs:17:14
   |
LL |     for _ in t {}
   |              ^ the trait `Step` is not implemented for `T`
   |
   = note: required for `std::ops::Range<T>` to implement `Iterator`
   = note: required for `std::ops::Range<T>` to implement `IntoIterator`
help: consider restricting type parameter `T` with unstable trait `Step`
   |
LL | pub fn baz<T: std::iter::Step>(t: std::ops::Range<T>) {
   |             +++++++++++++++++

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0277`.