Adding consider changing to & suggestion for let bindings

src/librustc_borrowck/borrowck/gather_loans/move_error.rs

@@ -73,9 +73,19 @@ fn report_move_errors<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>, errors: &Vec<Move
  let mut err = report_cannot_move_out_of(bccx, error.move_from.clone());
  let mut is_first_note = true;
  match error.move_to_places.get(0) {
- Some(&MovePlace { pat_source: PatternSource::LetDecl(_), .. }) => {
+ Some(&MovePlace { pat_source: PatternSource::LetDecl(ref e), .. }) => {
  // ignore patterns that are found at the top-level of a `let`;
  // see `get_pattern_source()` for details
+ let initializer =
+ e.init.as_ref().expect("should have an initializer to get an error");
+ if let Ok(snippet) = bccx.tcx.sess.codemap().span_to_snippet(initializer.span) {
+ if snippet.len() > 10 {
+ err.help(&format!("consider borrowing this with `&`"));
+ } else {
+ err.help(&format!("consider changing to `&{}`", snippet));
+ }
+ }
+
  }
  _ => {
  for move_to in &error.move_to_places {

src/test/ui/issue-40402-ref-hints/issue-40402-1.stderr

@@ -3,6 +3,8 @@ error[E0507]: cannot move out of indexed content
  |
 19 | let e = f.v[0];
  | ^^^^^^ cannot move out of indexed content
+ |
+ = help: consider changing to `&f.v[0]`
 
 error: aborting due to previous error