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Modify find_expr from Span to better account for closures

Start pointing to where bindings were declared when they are captured in closures:

```
error[E0597]: `x` does not live long enough
  --> $DIR/suggest-return-closure.rs:23:9
   |
LL |     let x = String::new();
   |         - binding `x` declared here
...
LL |     |c| {
   |     --- value captured here
LL |         x.push(c);
   |         ^ borrowed value does not live long enough
...
LL | }
   | -- borrow later used here
   | |
   | `x` dropped here while still borrowed
```

Suggest cloning in more cases involving closures:

```
error[E0507]: cannot move out of `foo` in pattern guard
  --> $DIR/issue-27282-move-ref-mut-into-guard.rs:11:19
   |
LL |             if { (|| { let mut bar = foo; bar.take() })(); false } => {},
   |                   ^^                 --- move occurs because `foo` has type `&mut Option<&i32>`, which does not implement the `Copy` trait
   |                   |
   |                   `foo` is moved here
   |
   = note: variables bound in patterns cannot be moved from until after the end of the pattern guard
help: consider cloning the value if the performance cost is acceptable
   |
LL |             if { (|| { let mut bar = foo.clone(); bar.take() })(); false } => {},
   |                                         ++++++++
```
This commit is contained in:
Esteban Küber 2024-04-18 20:41:43 +00:00
parent ef8b9dcf23
commit 4aba2c55e6
31 changed files with 202 additions and 31 deletions

View file

@ -1964,7 +1964,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
pub(crate) fn find_expr(&self, span: Span) -> Option<&hir::Expr<'_>> {
let tcx = self.infcx.tcx;
let body_id = tcx.hir_node(self.mir_hir_id()).body_id()?;
let mut expr_finder = FindExprBySpan::new(span);
let mut expr_finder = FindExprBySpan::new(span, tcx);
expr_finder.visit_expr(tcx.hir().body(body_id).value);
expr_finder.result
}
@ -1998,14 +1998,14 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
};
let mut expr_finder =
FindExprBySpan::new(self.body.local_decls[*index1].source_info.span);
FindExprBySpan::new(self.body.local_decls[*index1].source_info.span, tcx);
expr_finder.visit_expr(hir.body(body_id).value);
let Some(index1) = expr_finder.result else {
note_default_suggestion();
return;
};
expr_finder = FindExprBySpan::new(self.body.local_decls[*index2].source_info.span);
expr_finder = FindExprBySpan::new(self.body.local_decls[*index2].source_info.span, tcx);
expr_finder.visit_expr(hir.body(body_id).value);
let Some(index2) = expr_finder.result else {
note_default_suggestion();