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Do not suggest invalid code in pattern with loop
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JohnTitor committed Jan 12, 2021
1 parent 0406441 commit 4362da1
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Showing 3 changed files with 29 additions and 1 deletion.
Original file line number Diff line number Diff line change
Expand Up @@ -141,6 +141,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
self.add_moved_or_invoked_closure_note(location, used_place, &mut err);

let mut is_loop_move = false;
let mut in_pattern = false;

for move_site in &move_site_vec {
let move_out = self.move_data.moves[(*move_site).moi];
Expand Down Expand Up @@ -256,6 +257,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
"ref ".to_string(),
Applicability::MachineApplicable,
);
in_pattern = true;
}

if let Some(DesugaringKind::ForLoop(_)) = move_span.desugaring_kind() {
Expand Down Expand Up @@ -302,7 +304,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
let place = &self.move_data.move_paths[mpi].place;
let ty = place.ty(self.body, self.infcx.tcx).ty;

if is_loop_move {
// If we're in pattern, we do nothing in favor of the previous suggestion (#80913).
if is_loop_move & !in_pattern {
if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() {
// We have a `&mut` ref, we need to reborrow on each iteration (#62112).
err.span_suggestion_verbose(
Expand Down
10 changes: 10 additions & 0 deletions src/test/ui/borrowck/move-in-pattern-mut-in-loop.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
// Regression test for #80913.

fn main() {
let mut x = 42_i32;
let mut opt = Some(&mut x);
for _ in 0..5 {
if let Some(mut _x) = opt {}
//~^ ERROR: use of moved value
}
}
15 changes: 15 additions & 0 deletions src/test/ui/borrowck/move-in-pattern-mut-in-loop.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
error[E0382]: use of moved value
--> $DIR/move-in-pattern-mut-in-loop.rs:7:21
|
LL | if let Some(mut _x) = opt {}
| ^^^^^^ value moved here, in previous iteration of loop
|
= note: move occurs because value has type `&mut i32`, which does not implement the `Copy` trait
help: borrow this field in the pattern to avoid moving `opt.0`
|
LL | if let Some(ref mut _x) = opt {}
| ^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0382`.

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