// Issue #62007: assigning over a const-index projection of an array // (in this case, `list[I] = n;`) should in theory be able to kill all borrows // of `list[0]`, so that `list[0]` could be borrowed on the next // iteration through the loop. // // Currently the compiler does not allow this. We may want to consider // loosening that restriction in the future. (However, doing so would // at *least* require T-lang team approval, and probably an RFC; e.g. // such loosening might make complicate the user's mental mode; it // also would make code more brittle in the face of refactorings that // replace constants with variables. #![allow(dead_code)] struct List { value: T, next: Option>>, } fn to_refs(mut list: [&mut List; 2]) -> Vec<&mut T> { let mut result = vec![]; loop { result.push(&mut list[0].value); //~ ERROR cannot borrow `list[_].value` as mutable if let Some(n) = list[0].next.as_mut() { //~ ERROR cannot borrow `list[_].next` as mutable list[0] = n; } else { return result; } } } fn main() {}