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Fix move errors for index expressions

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The suggestion logic gave up too early, which kept it from suggesting
borrowing index expressions.
This commit is contained in:
ashtneoi 2018-08-07 23:44:35 -07:00
parent 54ddb36ce7
commit 8080bdf275
2 changed files with 64 additions and 43 deletions
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46
src/librustc_mir/borrow_check/move_errors.rs
View File

@ -341,38 +341,32 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
move_from,
..
} => {
let mut suggest_change_head_expr = false;
match move_from {
let try_remove_deref = match move_from {
Place::Projection(box PlaceProjection {
elem: ProjectionElem::Deref,
..
}) => {
// This is false for (e.g.) index expressions `a[b]`,
// which roughly desugar to `*Index::index(&a, b)` or
// `*IndexMut::index_mut(&mut a, b)`.
if snippet.starts_with('*') {
err.span_suggestion(
span,
"consider removing this dereference operator",
(&snippet[1..]).to_owned(),
);
suggest_change_head_expr = true;
}
}
_ => {
err.span_suggestion(
span,
"consider using a reference instead",
format!("&{}", snippet),
);
suggest_change_head_expr = true;
}
}) => true,
_ => false,
};
if try_remove_deref && snippet.starts_with('*') {
// This is false for (e.g.) index expressions `a[b]`,
// which roughly desugar to `*Index::index(&a, b)` or
// `*IndexMut::index_mut(&mut a, b)`.
err.span_suggestion(
span,
"consider removing this dereference operator",
snippet[1..].to_owned(),
);
} else {
err.span_suggestion(
span,
"consider using a reference instead",
format!("&{}", snippet),
);
}
binds_to.sort();
binds_to.dedup();
if !suggest_change_head_expr {
self.add_move_error_suggestions(err, &binds_to);
}
self.add_move_error_labels(err, &binds_to);
}
GroupedMoveError::MovesFromValue { mut binds_to, .. } => {

61
src/test/ui/suggestions/dont-suggest-ref.stderr
View File

@ -188,8 +188,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:111:17
|
LL | let X(_t) = vs_[0];
| -- ^^^^^^ cannot move out of borrowed content
| |
| -- ^^^^^^
| | |
| | cannot move out of borrowed content
| | help: consider using a reference instead: `&vs_[0]`
| data moved here
|
note: move occurs because _t has type `Y`, which does not implement the `Copy` trait
@ -202,8 +204,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:115:30
|
LL | if let Either::One(_t) = vr[0] { }
| -- ^^^^^ cannot move out of borrowed content
| |
| -- ^^^^^
| | |
| | cannot move out of borrowed content
| | help: consider using a reference instead: `&vr[0]`
| data moved here
|
note: move occurs because _t has type `X`, which does not implement the `Copy` trait
@ -216,8 +220,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:119:33
|
LL | while let Either::One(_t) = vr[0] { }
| -- ^^^^^ cannot move out of borrowed content
| |
| -- ^^^^^
| | |
| | cannot move out of borrowed content
| | help: consider using a reference instead: `&vr[0]`
| data moved here
|
note: move occurs because _t has type `X`, which does not implement the `Copy` trait
@ -230,7 +236,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:123:11
|
LL | match vr[0] {
| ^^^^^ cannot move out of borrowed content
| ^^^^^
| |
| cannot move out of borrowed content
| help: consider using a reference instead: `&vr[0]`
...
LL | Either::One(_t)
| -- data moved here
@ -245,7 +254,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:130:11
|
LL | match vr[0] {
| ^^^^^ cannot move out of borrowed content
| ^^^^^
| |
| cannot move out of borrowed content
| help: consider using a reference instead: `&vr[0]`
...
LL | Either::One(_t) => (),
| -- data moved here
@ -260,8 +272,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:139:17
|
LL | let X(_t) = vsm[0];
| -- ^^^^^^ cannot move out of borrowed content
| |
| -- ^^^^^^
| | |
| | cannot move out of borrowed content
| | help: consider using a reference instead: `&vsm[0]`
| data moved here
|
note: move occurs because _t has type `Y`, which does not implement the `Copy` trait
@ -274,8 +288,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:143:30
|
LL | if let Either::One(_t) = vrm[0] { }
| -- ^^^^^^ cannot move out of borrowed content
| |
| -- ^^^^^^
| | |
| | cannot move out of borrowed content
| | help: consider using a reference instead: `&vrm[0]`
| data moved here
|
note: move occurs because _t has type `X`, which does not implement the `Copy` trait
@ -288,8 +304,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:147:33
|
LL | while let Either::One(_t) = vrm[0] { }
| -- ^^^^^^ cannot move out of borrowed content
| |
| -- ^^^^^^
| | |
| | cannot move out of borrowed content
| | help: consider using a reference instead: `&vrm[0]`
| data moved here
|
note: move occurs because _t has type `X`, which does not implement the `Copy` trait
@ -302,7 +320,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:151:11
|
LL | match vrm[0] {
| ^^^^^^ cannot move out of borrowed content
| ^^^^^^
| |
| cannot move out of borrowed content
| help: consider using a reference instead: `&vrm[0]`
...
LL | Either::One(_t)
| -- data moved here
@ -317,7 +338,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:158:11
|
LL | match vrm[0] {
| ^^^^^^ cannot move out of borrowed content
| ^^^^^^
| |
| cannot move out of borrowed content
| help: consider using a reference instead: `&vrm[0]`
...
LL | Either::One(_t) => (),
| -- data moved here
@ -332,7 +356,10 @@ error[E0507]: cannot move out of borrowed content
--> $DIR/dont-suggest-ref.rs:166:11
|
LL | match vrm[0] {
| ^^^^^^ cannot move out of borrowed content
| ^^^^^^
| |
| cannot move out of borrowed content
| help: consider using a reference instead: `&vrm[0]`
...
LL | Either::One(_t) => (),
| -- data moved here