help clause points to adding where clause on impl when it should be on function #104089
Description
Given the following code: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=e5d9c21342f0c0824ddba9445daf7cb1
struct A { x: String } struct B { x: String } impl From<A> for B { fn from(a: A) -> Self { B { x: a.x } } } impl B { pub fn from_many<T: Into<B> + Clone>(v: Vec<T>) -> Self { B { x: v.iter().map(|e| B::from(e.clone()).x).collect::<Vec<String>>().join(" ") } } } fn main() { let b: B = B { x: "foobar".to_string() }; let a: A = A { x: "frob".to_string() }; let ab: B = a.into(); println!("Hello, {}!", ab.x); }The current output is:
error[[E0277]](https://doc.rust-lang.org/stable/error-index.html#E0277): the trait bound `B: From<T>` is not satisfied --> src/main.rs:17:41 | 17 | B { x: v.iter().map(|e| B::from(e.clone()).x).collect::<Vec<String>>().join(" ") } | ------- ^^^^^^^^^ the trait `From<T>` is not implemented for `B` | | | required by a bound introduced by this call | help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement | 15 | impl B where B: From<T> { | ++++++++++++++++ Ideally the output should look like:
... help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement | pub fn from_many<T: Into<B> + Clone>(v: Vec<T>) -> Self where B: From<T> { ... } link to stack overflow: https://stackoverflow.com/questions/74342563/convert-vector-of-type-a-to-type-b-where-a-is-convertible-to-b?noredirect=1#comment131245422_74342563