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Merged
merged 8 commits into from
Dec 5, 2023
Merged

Tweak .clone() suggestion to work in more cases #118076

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03c88aa
Tweak `.clone()` suggestion to work in more cases
estebank Nov 19, 2023
98cfed7
Suggest cloning and point out obligation errors on move error
estebank Nov 20, 2023
90db536
Tweak output on specific case
estebank Nov 20, 2023
1c69c6a
Mark more tests as `run-rustfix`
estebank Nov 20, 2023
a754fca
On "this .clone() is on the reference", provide more info
estebank Nov 21, 2023
210a672
Deduplicate some logic
estebank Nov 21, 2023
cc80106
Provide more suggestions for cloning immutable bindings
estebank Nov 21, 2023
a8faa82
Fix rebase
estebank Dec 4, 2023
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155 changes: 103 additions & 52 deletions compiler/rustc_borrowck/src/diagnostics/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ use rustc_hir::def::{CtorKind, Namespace};
use rustc_hir::CoroutineKind;
use rustc_index::IndexSlice;
use rustc_infer::infer::BoundRegionConversionTime;
use rustc_infer::traits::{FulfillmentErrorCode, SelectionError};
use rustc_middle::mir::tcx::PlaceTy;
use rustc_middle::mir::{
AggregateKind, CallSource, ConstOperand, FakeReadCause, Local, LocalInfo, LocalKind, Location,
Expand All @@ -24,10 +25,9 @@ use rustc_mir_dataflow::move_paths::{InitLocation, LookupResult};
use rustc_span::def_id::LocalDefId;
use rustc_span::{symbol::sym, Span, Symbol, DUMMY_SP};
use rustc_target::abi::{FieldIdx, VariantIdx};
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
use rustc_trait_selection::traits::{
type_known_to_meet_bound_modulo_regions, Obligation, ObligationCause,
};
use rustc_trait_selection::infer::InferCtxtExt;
use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt as _;
use rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions;

use super::borrow_set::BorrowData;
use super::MirBorrowckCtxt;
Expand Down Expand Up @@ -1043,7 +1043,38 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
}
CallKind::Normal { self_arg, desugaring, method_did, method_args } => {
let self_arg = self_arg.unwrap();
let mut has_sugg = false;
let tcx = self.infcx.tcx;
// Avoid pointing to the same function in multiple different
// error messages.
if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span) {
self.explain_iterator_advancement_in_for_loop_if_applicable(
err,
span,
&move_spans,
);

let func = tcx.def_path_str(method_did);
err.subdiagnostic(CaptureReasonNote::FuncTakeSelf {
func,
place_name: place_name.clone(),
span: self_arg.span,
});
}
let parent_did = tcx.parent(method_did);
let parent_self_ty =
matches!(tcx.def_kind(parent_did), rustc_hir::def::DefKind::Impl { .. })
.then_some(parent_did)
.and_then(|did| match tcx.type_of(did).instantiate_identity().kind() {
ty::Adt(def, ..) => Some(def.did()),
_ => None,
});
let is_option_or_result = parent_self_ty.is_some_and(|def_id| {
matches!(tcx.get_diagnostic_name(def_id), Some(sym::Option | sym::Result))
});
if is_option_or_result && maybe_reinitialized_locations_is_empty {
err.subdiagnostic(CaptureReasonLabel::BorrowContent { var_span });
}
if let Some((CallDesugaringKind::ForLoopIntoIter, _)) = desugaring {
let ty = moved_place.ty(self.body, tcx).ty;
let suggest = match tcx.get_diagnostic_item(sym::IntoIterator) {
Expand Down Expand Up @@ -1108,7 +1139,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
// Erase and shadow everything that could be passed to the new infcx.
let ty = moved_place.ty(self.body, tcx).ty;

if let ty::Adt(def, args) = ty.kind()
if let ty::Adt(def, args) = ty.peel_refs().kind()
&& Some(def.did()) == tcx.lang_items().pin_type()
&& let ty::Ref(_, _, hir::Mutability::Mut) = args.type_at(0).kind()
&& let self_ty = self.infcx.instantiate_binder_with_fresh_vars(
Expand All @@ -1124,56 +1155,76 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
span: move_span.shrink_to_hi(),
},
);
has_sugg = true;
}
if let Some(clone_trait) = tcx.lang_items().clone_trait()
&& let trait_ref = ty::TraitRef::new(tcx, clone_trait, [ty])
&& let o = Obligation::new(
tcx,
ObligationCause::dummy(),
self.param_env,
ty::Binder::dummy(trait_ref),
)
&& self.infcx.predicate_must_hold_modulo_regions(&o)
{
err.span_suggestion_verbose(
move_span.shrink_to_hi(),
"you can `clone` the value and consume it, but this might not be \
your desired behavior",
".clone()".to_string(),
Applicability::MaybeIncorrect,
);
if let Some(clone_trait) = tcx.lang_items().clone_trait() {
let sugg = if moved_place
.iter_projections()
.any(|(_, elem)| matches!(elem, ProjectionElem::Deref))
{
vec![
// We use the fully-qualified path because `.clone()` can
// sometimes choose `<&T as Clone>` instead of `<T as Clone>`
// when going through auto-deref, so this ensures that doesn't
// happen, causing suggestions for `.clone().clone()`.
(move_span.shrink_to_lo(), format!("<{ty} as Clone>::clone(&")),
(move_span.shrink_to_hi(), ")".to_string()),
]
} else {
vec![(move_span.shrink_to_hi(), ".clone()".to_string())]
};
if let Some(errors) =
self.infcx.could_impl_trait(clone_trait, ty, self.param_env)
&& !has_sugg
{
let msg = match &errors[..] {
[] => "you can `clone` the value and consume it, but this \
might not be your desired behavior"
.to_string(),
[error] => {
format!(
"you could `clone` the value and consume it, if \
the `{}` trait bound could be satisfied",
error.obligation.predicate,
)
}
[errors @ .., last] => {
format!(
"you could `clone` the value and consume it, if \
the following trait bounds could be satisfied: {} \
and `{}`",
errors
.iter()
.map(|e| format!("`{}`", e.obligation.predicate))
.collect::<Vec<_>>()
.join(", "),
last.obligation.predicate,
)
}
};
err.multipart_suggestion_verbose(
msg,
sugg.clone(),
Applicability::MaybeIncorrect,
);
for error in errors {
if let FulfillmentErrorCode::CodeSelectionError(
SelectionError::Unimplemented,
) = error.code
&& let ty::PredicateKind::Clause(ty::ClauseKind::Trait(
pred,
)) = error.obligation.predicate.kind().skip_binder()
{
self.infcx.err_ctxt().suggest_derive(
&error.obligation,
err,
error.obligation.predicate.kind().rebind(pred),
);
}
}
}
}
}
// Avoid pointing to the same function in multiple different
// error messages.
if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span) {
self.explain_iterator_advancement_in_for_loop_if_applicable(
err,
span,
&move_spans,
);

let func = tcx.def_path_str(method_did);
err.subdiagnostic(CaptureReasonNote::FuncTakeSelf {
func,
place_name,
span: self_arg.span,
});
}
let parent_did = tcx.parent(method_did);
let parent_self_ty =
matches!(tcx.def_kind(parent_did), rustc_hir::def::DefKind::Impl { .. })
.then_some(parent_did)
.and_then(|did| match tcx.type_of(did).instantiate_identity().kind() {
ty::Adt(def, ..) => Some(def.did()),
_ => None,
});
let is_option_or_result = parent_self_ty.is_some_and(|def_id| {
matches!(tcx.get_diagnostic_name(def_id), Some(sym::Option | sym::Result))
});
if is_option_or_result && maybe_reinitialized_locations_is_empty {
err.subdiagnostic(CaptureReasonLabel::BorrowContent { var_span });
}
}
// Other desugarings takes &self, which cannot cause a move
_ => {}
Expand Down
102 changes: 101 additions & 1 deletion compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,15 +3,18 @@ use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed
use rustc_hir as hir;
use rustc_hir::intravisit::Visitor;
use rustc_hir::Node;
use rustc_infer::traits;
use rustc_middle::mir::{Mutability, Place, PlaceRef, ProjectionElem};
use rustc_middle::ty::{self, InstanceDef, Ty, TyCtxt};
use rustc_middle::ty::{self, InstanceDef, ToPredicate, Ty, TyCtxt};
use rustc_middle::{
hir::place::PlaceBase,
mir::{self, BindingForm, Local, LocalDecl, LocalInfo, LocalKind, Location},
};
use rustc_span::symbol::{kw, Symbol};
use rustc_span::{sym, BytePos, DesugaringKind, Span};
use rustc_target::abi::FieldIdx;
use rustc_trait_selection::infer::InferCtxtExt;
use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt;

use crate::diagnostics::BorrowedContentSource;
use crate::util::FindAssignments;
Expand Down Expand Up @@ -1212,6 +1215,103 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
if let Some(hir_id) = hir_id
&& let Some(hir::Node::Local(local)) = hir_map.find(hir_id)
{
let tables = self.infcx.tcx.typeck(def_id.as_local().unwrap());
if let Some(clone_trait) = self.infcx.tcx.lang_items().clone_trait()
&& let Some(expr) = local.init
&& let ty = tables.node_type_opt(expr.hir_id)
&& let Some(ty) = ty
&& let ty::Ref(..) = ty.kind()
{
match self
.infcx
.could_impl_trait(clone_trait, ty.peel_refs(), self.param_env)
.as_deref()
{
Some([]) => {
// The type implements Clone.
err.span_help(
expr.span,
format!(
"you can `clone` the `{}` value and consume it, but this \
might not be your desired behavior",
ty.peel_refs(),
),
);
}
None => {
if let hir::ExprKind::MethodCall(segment, _rcvr, [], span) =
expr.kind
&& segment.ident.name == sym::clone
{
err.span_help(
span,
format!(
"`{}` doesn't implement `Clone`, so this call clones \
the reference `{ty}`",
ty.peel_refs(),
),
);
}
// The type doesn't implement Clone.
let trait_ref = ty::Binder::dummy(ty::TraitRef::new(
self.infcx.tcx,
clone_trait,
[ty.peel_refs()],
));
let obligation = traits::Obligation::new(
self.infcx.tcx,
traits::ObligationCause::dummy(),
self.param_env,
trait_ref,
);
self.infcx.err_ctxt().suggest_derive(
&obligation,
err,
trait_ref.to_predicate(self.infcx.tcx),
);
}
Some(errors) => {
if let hir::ExprKind::MethodCall(segment, _rcvr, [], span) =
expr.kind
&& segment.ident.name == sym::clone
{
err.span_help(
span,
format!(
"`{}` doesn't implement `Clone` because its \
implementations trait bounds could not be met, so \
this call clones the reference `{ty}`",
ty.peel_refs(),
),
);
err.note(format!(
"the following trait bounds weren't met: {}",
errors
.iter()
.map(|e| e.obligation.predicate.to_string())
.collect::<Vec<_>>()
.join("\n"),
));
}
// The type doesn't implement Clone because of unmet obligations.
for error in errors {
if let traits::FulfillmentErrorCode::CodeSelectionError(
traits::SelectionError::Unimplemented,
) = error.code
&& let ty::PredicateKind::Clause(ty::ClauseKind::Trait(
pred,
)) = error.obligation.predicate.kind().skip_binder()
{
self.infcx.err_ctxt().suggest_derive(
&error.obligation,
err,
error.obligation.predicate.kind().rebind(pred),
);
}
}
}
}
}
let (changing, span, sugg) = match local.ty {
Some(ty) => ("changing", ty.span, message),
None => {
Expand Down
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