error[E0277]: a value of type `Vec` cannot be built from an iterator over elements of type `&X` --> $DIR/invalid-iterator-chain-fixable.rs:7:7 | LL | let i = i.map(|x| x.clone()); | ------- this method call is cloning the reference `&X`, not `X` which doesn't implement `Clone` LL | i.collect() | ^^^^^^^ value of type `Vec` cannot be built from `std::iter::Iterator` | = help: the trait `FromIterator<&_>` is not implemented for `Vec` but trait `FromIterator<_>` is implemented for it = help: for that trait implementation, expected `X`, found `&X` note: the method call chain might not have had the expected associated types --> $DIR/invalid-iterator-chain-fixable.rs:5:26 | LL | fn iter_to_vec<'b, X>(i: Iter<'b, X>) -> Vec { | ^^^^^^^^^^^ `Iterator::Item` is `&X` here LL | let i = i.map(|x| x.clone()); | ------------------ `Iterator::Item` remains `&X` here note: required by a bound in `collect` --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL help: consider further restricting type parameter `X` | LL | fn iter_to_vec<'b, X>(i: Iter<'b, X>) -> Vec where X: Clone { | ++++++++++++++ error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()` --> $DIR/invalid-iterator-chain-fixable.rs:17:33 | LL | println!("{}", scores.sum::()); | --- ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator` | | | required by a bound introduced by this call | = help: the trait `Sum<()>` is not implemented for `i32` = help: the following other types implement trait `Sum`: `i32` implements `Sum<&i32>` `i32` implements `Sum` note: the method call chain might not have had the expected associated types --> $DIR/invalid-iterator-chain-fixable.rs:14:10 | LL | let v = vec![(0, 0)]; | ------------ this expression has type `Vec<({integer}, {integer})>` LL | let scores = v LL | .iter() | ------ `Iterator::Item` is `&({integer}, {integer})` here LL | .map(|(a, b)| { | __________^ LL | | a + b; LL | | }); | |__________^ `Iterator::Item` changed to `()` here note: required by a bound in `std::iter::Iterator::sum` --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL help: consider removing this semicolon | LL - a + b; LL + a + b | error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()` --> $DIR/invalid-iterator-chain-fixable.rs:25:20 | LL | .sum::(), | --- ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator` | | | required by a bound introduced by this call | = help: the trait `Sum<()>` is not implemented for `i32` = help: the following other types implement trait `Sum`: `i32` implements `Sum<&i32>` `i32` implements `Sum` note: the method call chain might not have had the expected associated types --> $DIR/invalid-iterator-chain-fixable.rs:23:14 | LL | vec![0, 1] | ---------- this expression has type `Vec<{integer}>` LL | .iter() | ------ `Iterator::Item` is `&{integer}` here LL | .map(|x| x * 2) | -------------- `Iterator::Item` changed to `{integer}` here LL | .map(|x| { x; }) | ^^^^^^^^^^^^^^^ `Iterator::Item` changed to `()` here LL | .map(|x| { x }) | -------------- `Iterator::Item` remains `()` here note: required by a bound in `std::iter::Iterator::sum` --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL help: consider removing this semicolon | LL - .map(|x| { x; }) LL + .map(|x| { x }) | error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()` --> $DIR/invalid-iterator-chain-fixable.rs:27:60 | LL | println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::()); | --- ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator` | | | required by a bound introduced by this call | = help: the trait `Sum<()>` is not implemented for `i32` = help: the following other types implement trait `Sum`: `i32` implements `Sum<&i32>` `i32` implements `Sum` note: the method call chain might not have had the expected associated types --> $DIR/invalid-iterator-chain-fixable.rs:27:38 | LL | println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::()); | ---------- ------ ^^^^^^^^^^^^^^^ `Iterator::Item` changed to `()` here | | | | | `Iterator::Item` is `&{integer}` here | this expression has type `Vec<{integer}>` note: required by a bound in `std::iter::Iterator::sum` --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL help: consider removing this semicolon | LL - println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::()); LL + println!("{}", vec![0, 1].iter().map(|x| { x }).sum::()); | error[E0277]: a value of type `Vec` cannot be built from an iterator over elements of type `()` --> $DIR/invalid-iterator-chain-fixable.rs:36:25 | LL | let g: Vec = f.collect(); | ^^^^^^^ value of type `Vec` cannot be built from `std::iter::Iterator` | = help: the trait `FromIterator<()>` is not implemented for `Vec` but trait `FromIterator` is implemented for it = help: for that trait implementation, expected `i32`, found `()` note: the method call chain might not have had the expected associated types --> $DIR/invalid-iterator-chain-fixable.rs:32:15 | LL | let a = vec![0]; | ------- this expression has type `Vec<{integer}>` LL | let b = a.into_iter(); | ----------- `Iterator::Item` is `{integer}` here LL | let c = b.map(|x| x + 1); | -------------- `Iterator::Item` remains `{integer}` here LL | let d = c.filter(|x| *x > 10 ); | -------------------- `Iterator::Item` remains `{integer}` here LL | let e = d.map(|x| { | _______________^ LL | | x + 1; LL | | }); | |______^ `Iterator::Item` changed to `()` here LL | let f = e.filter(|_| false); | ----------------- `Iterator::Item` remains `()` here note: required by a bound in `collect` --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL help: consider removing this semicolon | LL - x + 1; LL + x + 1 | error: aborting due to 5 previous errors For more information about this error, try `rustc --explain E0277`.