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Clone suggestions #95115

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Clone suggestions #95115

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2ed5f25
Move code that finds missing bounds into a function
WaffleLapkin Mar 8, 2022
35c9ddf
Remove some duplicating `self.infcx.tcx`
WaffleLapkin Mar 8, 2022
9b7f17f
Implement clone suggestion on move errors
WaffleLapkin Mar 19, 2022
4c5de71
Bless tests
WaffleLapkin Mar 19, 2022
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182 changes: 117 additions & 65 deletions compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
location, desired_action, moved_place, used_place, span, mpi
);

let tcx = self.infcx.tcx;
let use_spans =
self.move_spans(moved_place, location).or_else(|| self.borrow_spans(span, location));
let span = use_spans.args_or_use();
Expand Down Expand Up @@ -174,12 +175,15 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
let mut is_loop_move = false;
let mut in_pattern = false;

let mut to_clone_spans = Vec::new();

for move_site in &move_site_vec {
let move_out = self.move_data.moves[(*move_site).moi];
let moved_place = &self.move_data.move_paths[move_out.path].place;

let move_spans = self.move_spans(moved_place.as_ref(), move_out.source);
let move_span = move_spans.args_or_use();
to_clone_spans.push(move_spans.var_or_use_path_span());

let move_msg = if move_spans.for_closure() { " into closure" } else { "" };

Expand Down Expand Up @@ -243,11 +247,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
);
}

let ty = used_place.ty(self.body, self.infcx.tcx).ty;
let ty = used_place.ty(self.body, tcx).ty;
let needs_note = match ty.kind() {
ty::Closure(id, _) => {
let tables = self.infcx.tcx.typeck(id.expect_local());
let hir_id = self.infcx.tcx.hir().local_def_id_to_hir_id(id.expect_local());
let tables = tcx.typeck(id.expect_local());
let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());

tables.closure_kind_origins().get(hir_id).is_none()
}
Expand All @@ -256,7 +260,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {

let mpi = self.move_data.moves[move_out_indices[0]].path;
let place = &self.move_data.move_paths[mpi].place;
let ty = place.ty(self.body, self.infcx.tcx).ty;
let ty = place.ty(self.body, tcx).ty;

// If we're in pattern, we do nothing in favor of the previous suggestion (#80913).
if is_loop_move & !in_pattern {
Expand Down Expand Up @@ -285,61 +289,69 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
};

// Try to find predicates on *generic params* that would allow copying `ty`
let tcx = self.infcx.tcx;
let generics = tcx.generics_of(self.mir_def_id());
if let Some(hir_generics) = tcx
.typeck_root_def_id(self.mir_def_id().to_def_id())
.as_local()
.and_then(|def_id| tcx.hir().get_generics(def_id))
{
let predicates: Result<Vec<_>, _> = tcx.infer_ctxt().enter(|infcx| {
let mut fulfill_cx =
<dyn rustc_infer::traits::TraitEngine<'_>>::new(infcx.tcx);

let copy_did = infcx.tcx.lang_items().copy_trait().unwrap();
let cause = ObligationCause::new(
span,
self.mir_hir_id(),
rustc_infer::traits::ObligationCauseCode::MiscObligation,
);
fulfill_cx.register_bound(
&infcx,
self.param_env,
// Erase any region vids from the type, which may not be resolved
infcx.tcx.erase_regions(ty),
copy_did,
cause,
);
// Select all, including ambiguous predicates
let errors = fulfill_cx.select_all_or_error(&infcx);

// Only emit suggestion if all required predicates are on generic
errors
.into_iter()
.map(|err| match err.obligation.predicate.kind().skip_binder() {
PredicateKind::Trait(predicate) => {
match predicate.self_ty().kind() {
ty::Param(param_ty) => Ok((
generics.type_param(param_ty, tcx),
predicate.trait_ref.print_only_trait_path().to_string(),
)),
_ => Err(()),
}
}
_ => Err(()),
})
.collect()
});
let copy_did = tcx.lang_items().copy_trait().unwrap();
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There's a method, I think called expect_lang_item or similar (don't have the editor open right now to find it) that does that unwrap for you in a non-ICEy way.

let copy_predicates =
self.try_find_missing_generic_bounds(ty, copy_did, generics, span);

let clone_did = tcx.lang_items().clone_trait().unwrap();
let clone_predicates =
self.try_find_missing_generic_bounds(ty, clone_did, generics, span);

match (copy_predicates, clone_predicates) {
// The type is already `Clone`, suggest cloning all values
(_, Ok(clone_predicates)) if clone_predicates.is_empty() => {
err.multipart_suggestion_verbose(
&format!("consider cloning {}", note_msg),
to_clone_spans
.into_iter()
.map(|move_span| {
(move_span.shrink_to_hi(), ".clone()".to_owned())
})
.collect(),
Applicability::MaybeIncorrect,
);
}
// The type can *not* be `Copy`, but can be `Clone`, suggest adding bounds to make the type `Clone` and then cloning all values
(Err(_), Ok(clone_predicates)) => {
suggest_constraining_type_params(
tcx,
hir_generics,
&mut err,
clone_predicates.iter().map(|(param, constraint)| {
(param.name.as_str(), &**constraint, None)
}),
);

if let Ok(predicates) = predicates {
suggest_constraining_type_params(
tcx,
hir_generics,
&mut err,
predicates.iter().map(|(param, constraint)| {
(param.name.as_str(), &**constraint, None)
}),
);
err.multipart_suggestion_verbose(
&format!("...and cloning {}", note_msg),
to_clone_spans
.into_iter()
.map(|move_span| {
(move_span.shrink_to_hi(), ".clone()".to_owned())
})
.collect(),
Applicability::MaybeIncorrect,
);
}
// The type can be `Copy`, suggest adding bound to make it `Copy`
(Ok(copy_predicates), _) => {
suggest_constraining_type_params(
tcx,
hir_generics,
&mut err,
copy_predicates.iter().map(|(param, constraint)| {
(param.name.as_str(), &**constraint, None)
}),
);
}
// The type can never be `Clone` or `Copy`, there is nothing to suggest :(
(Err(_), Err(_)) => {}
}
}

Expand All @@ -364,7 +376,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
));

// Check first whether the source is accessible (issue #87060)
if self.infcx.tcx.sess.source_map().span_to_snippet(deref_target).is_ok() {
if tcx.sess.source_map().span_to_snippet(deref_target).is_ok() {
err.span_note(deref_target, "deref defined here");
}
}
Expand Down Expand Up @@ -1047,6 +1059,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
location, name, borrow, drop_span, borrow_spans
);

let tcx = self.infcx.tcx;
let borrow_span = borrow_spans.var_or_use_path_span();
if let BorrowExplanation::MustBeValidFor {
category,
Expand Down Expand Up @@ -1083,19 +1096,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
format!(
"...but `{}` will be dropped here, when the {} returns",
name,
self.infcx
.tcx
.hir()
tcx.hir()
.opt_name(fn_hir_id)
.map(|name| format!("function `{}`", name))
.unwrap_or_else(|| {
match &self
.infcx
.tcx
.typeck(self.mir_def_id())
.node_type(fn_hir_id)
.kind()
{
match &tcx.typeck(self.mir_def_id()).node_type(fn_hir_id).kind() {
ty::Closure(..) => "enclosing closure",
ty::Generator(..) => "enclosing generator",
kind => bug!("expected closure or generator, found {:?}", kind),
Expand All @@ -1117,7 +1122,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
if let BorrowExplanation::MustBeValidFor { .. } = explanation {
} else {
explanation.add_explanation_to_diagnostic(
self.infcx.tcx,
tcx,
&self.body,
&self.local_names,
&mut err,
Expand All @@ -1135,7 +1140,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
borrow_spans.args_span_label(&mut err, format!("value captured here{}", within));

explanation.add_explanation_to_diagnostic(
self.infcx.tcx,
tcx,
&self.body,
&self.local_names,
&mut err,
Expand Down Expand Up @@ -2256,6 +2261,53 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
}
}
}

/// Tries to find bounds on `generics` that satisfy `ty: required_trait_did` bound.
fn try_find_missing_generic_bounds(
&self,
ty: Ty<'tcx>,
required_trait_did: DefId,
generics: &'tcx ty::Generics,
obligation_cause_span: Span,
) -> Result<Vec<(&'tcx ty::GenericParamDef, String)>, ()> {
let tcx = self.infcx.tcx;
let predicates: Result<Vec<_>, _> = tcx.infer_ctxt().enter(|infcx| {
let mut fulfill_cx = <dyn rustc_infer::traits::TraitEngine<'_>>::new(infcx.tcx);

let cause = ObligationCause::new(
obligation_cause_span,
self.mir_hir_id(),
rustc_infer::traits::ObligationCauseCode::MiscObligation,
);
fulfill_cx.register_bound(
&infcx,
self.param_env,
// Erase any region vids from the type, which may not be resolved
infcx.tcx.erase_regions(ty),
required_trait_did,
cause,
);
// Select all, including ambiguous predicates
let errors = fulfill_cx.select_all_or_error(&infcx);

// Only emit suggestion if all required predicates are on generic
errors
.into_iter()
.map(|err| match err.obligation.predicate.kind().skip_binder() {
PredicateKind::Trait(predicate) => match predicate.self_ty().kind() {
ty::Param(param_ty) => Ok((
generics.type_param(param_ty, tcx),
predicate.trait_ref.print_only_trait_path().to_string(),
)),
_ => Err(()),
},
_ => Err(()),
})
.collect()
});

predicates
}
}

#[derive(Debug)]
Expand Down
5 changes: 5 additions & 0 deletions src/test/ui/moves/issue-46099-move-in-macro.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,11 @@ LL | let b = Box::new(true);
| - move occurs because `b` has type `Box<bool>`, which does not implement the `Copy` trait
LL | test!({b});
| ^ value used here after move
|
help: consider cloning `b`
|
LL | test!({b.clone()});
| ++++++++

error: aborting due to previous error

Expand Down
17 changes: 17 additions & 0 deletions src/test/ui/moves/move-fn-self-receiver.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,10 @@ note: this function takes ownership of the receiver `self`, which moves `val.0`
LL | fn into_iter(self) -> Self::IntoIter;
| ^^^^
= note: move occurs because `val.0` has type `Vec<bool>`, which does not implement the `Copy` trait
help: consider cloning `val.0`
|
LL | val.0.clone().into_iter().next();
| ++++++++

error[E0382]: use of moved value: `foo`
--> $DIR/move-fn-self-receiver.rs:34:5
Expand Down Expand Up @@ -96,6 +100,10 @@ note: this function takes ownership of the receiver `self`, which moves `rc_foo`
|
LL | fn use_rc_self(self: Rc<Self>) {}
| ^^^^
help: consider cloning `rc_foo`
|
LL | rc_foo.clone().use_rc_self();
| ++++++++

error[E0382]: use of moved value: `foo_add`
--> $DIR/move-fn-self-receiver.rs:59:5
Expand Down Expand Up @@ -127,6 +135,10 @@ help: consider iterating over a slice of the `Vec<bool>`'s content to avoid movi
|
LL | for _val in &implicit_into_iter {}
| +
help: consider cloning `implicit_into_iter`
|
LL | for _val in implicit_into_iter.clone() {}
| ++++++++

error[E0382]: use of moved value: `explicit_into_iter`
--> $DIR/move-fn-self-receiver.rs:67:5
Expand All @@ -137,6 +149,11 @@ LL | for _val in explicit_into_iter.into_iter() {}
| ----------- `explicit_into_iter` moved due to this method call
LL | explicit_into_iter;
| ^^^^^^^^^^^^^^^^^^ value used here after move
|
help: consider cloning `explicit_into_iter`
|
LL | for _val in explicit_into_iter.clone().into_iter() {}
| ++++++++

error[E0382]: use of moved value: `container`
--> $DIR/move-fn-self-receiver.rs:71:5
Expand Down
5 changes: 5 additions & 0 deletions src/test/ui/moves/move-guard-same-consts.stderr
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Expand Up @@ -8,6 +8,11 @@ LL | (1, 2) if take(x) => (),
| - value moved here
LL | (1, 2) if take(x) => (),
| ^ value used here after move
|
help: consider cloning `x`
|
LL | (1, 2) if take(x.clone()) => (),
| ++++++++

error: aborting due to previous error

Expand Down
5 changes: 5 additions & 0 deletions src/test/ui/moves/move-in-guard-1.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,11 @@ LL | (1, _) if take(x) => (),
| - value moved here
LL | (_, 2) if take(x) => (),
| ^ value used here after move
|
help: consider cloning `x`
|
LL | (1, _) if take(x.clone()) => (),
| ++++++++

error: aborting due to previous error

Expand Down
5 changes: 5 additions & 0 deletions src/test/ui/moves/move-in-guard-2.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,11 @@ LL | let x: Box<_> = Box::new(1);
...
LL | (_, 2) if take(x) => (),
| ^ value used here after move
|
help: consider cloning `x`
|
LL | (_, 2) if take(x.clone()) => (),
| ++++++++

error: aborting due to previous error

Expand Down
8 changes: 8 additions & 0 deletions src/test/ui/moves/move-out-of-tuple-field.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,10 @@ LL | let z = x.0;
| ^^^ value used here after move
|
= note: move occurs because `x.0` has type `Box<i32>`, which does not implement the `Copy` trait
help: consider cloning `x.0`
|
LL | let y = x.0.clone();
| ++++++++

error[E0382]: use of moved value: `x.0`
--> $DIR/move-out-of-tuple-field.rs:12:13
Expand All @@ -17,6 +21,10 @@ LL | let z = x.0;
| ^^^ value used here after move
|
= note: move occurs because `x.0` has type `Box<isize>`, which does not implement the `Copy` trait
help: consider cloning `x.0`
|
LL | let y = x.0.clone();
| ++++++++

error: aborting due to 2 previous errors

Expand Down
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