error[E0271]: type mismatch resolving `, [closure@$DIR/issue-31173.rs:6:39: 6:43]> as Iterator>::Item == &_` --> $DIR/issue-31173.rs:10:10 | LL | .cloned() | ^^^^^^ expected reference, found `u8` | = note: expected reference `&_` found type `u8` note: required by a bound in `cloned` --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL | LL | Self: Sized + Iterator, | ^^^^^^^^^^^^ required by this bound in `cloned` error[E0599]: the method `collect` exists for struct `Cloned, [closure@$DIR/issue-31173.rs:6:39: 6:43]>>`, but its trait bounds were not satisfied --> $DIR/issue-31173.rs:12:10 | LL | .collect(); | ^^^^^^^ method cannot be called on `Cloned, [closure@$DIR/issue-31173.rs:6:39: 6:43]>>` due to unsatisfied trait bounds | ::: $SRC_DIR/core/src/iter/adapters/cloned.rs:LL:COL | LL | pub struct Cloned { | -------------------- doesn't satisfy `_: Iterator` | ::: $SRC_DIR/core/src/iter/adapters/take_while.rs:LL:COL | LL | pub struct TakeWhile { | -------------------------- doesn't satisfy `<_ as Iterator>::Item = &_` | = note: the following trait bounds were not satisfied: `, [closure@$DIR/issue-31173.rs:6:39: 6:43]> as Iterator>::Item = &_` which is required by `Cloned, [closure@$DIR/issue-31173.rs:6:39: 6:43]>>: Iterator` `Cloned, [closure@$DIR/issue-31173.rs:6:39: 6:43]>>: Iterator` which is required by `&mut Cloned, [closure@$DIR/issue-31173.rs:6:39: 6:43]>>: Iterator` error: aborting due to 2 previous errors Some errors have detailed explanations: E0271, E0599. For more information about an error, try `rustc --explain E0271`.