1 use crate::callee::{self, DeferredCallResolution};
2 use crate::method::{self, MethodCallee, SelfSource};
3 use crate::rvalue_scopes;
4 use crate::{BreakableCtxt, Diverges, Expectation, FnCtxt, LocalTy, RawTy};
5 use rustc_data_structures::captures::Captures;
6 use rustc_data_structures::fx::FxHashSet;
7 use rustc_errors::{Applicability, Diagnostic, ErrorGuaranteed, MultiSpan};
9 use rustc_hir::def::{CtorOf, DefKind, Res};
10 use rustc_hir::def_id::DefId;
11 use rustc_hir::lang_items::LangItem;
12 use rustc_hir::{ExprKind, GenericArg, Node, QPath};
13 use rustc_hir_analysis::astconv::generics::{
14 check_generic_arg_count_for_call, create_substs_for_generic_args,
16 use rustc_hir_analysis::astconv::{
17 AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch,
18 GenericArgCountResult, IsMethodCall, PathSeg,
20 use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
21 use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
22 use rustc_infer::infer::InferResult;
23 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
24 use rustc_middle::ty::error::TypeError;
25 use rustc_middle::ty::fold::TypeFoldable;
26 use rustc_middle::ty::visit::TypeVisitable;
27 use rustc_middle::ty::{
28 self, AdtKind, CanonicalUserType, DefIdTree, GenericParamDefKind, Ty, UserType,
30 use rustc_middle::ty::{GenericArgKind, SubstsRef, UserSelfTy, UserSubsts};
31 use rustc_session::lint;
32 use rustc_span::def_id::LocalDefId;
33 use rustc_span::hygiene::DesugaringKind;
34 use rustc_span::symbol::{kw, sym, Ident};
35 use rustc_span::{Span, DUMMY_SP};
36 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
37 use rustc_trait_selection::traits::{self, NormalizeExt, ObligationCauseCode, ObligationCtxt};
39 use std::collections::hash_map::Entry;
42 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
43 /// Produces warning on the given node, if the current point in the
44 /// function is unreachable, and there hasn't been another warning.
45 pub(in super::super) fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) {
46 // FIXME: Combine these two 'if' expressions into one once
47 // let chains are implemented
48 if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() {
49 // If span arose from a desugaring of `if` or `while`, then it is the condition itself,
50 // which diverges, that we are about to lint on. This gives suboptimal diagnostics.
51 // Instead, stop here so that the `if`- or `while`-expression's block is linted instead.
52 if !span.is_desugaring(DesugaringKind::CondTemporary)
53 && !span.is_desugaring(DesugaringKind::Async)
54 && !orig_span.is_desugaring(DesugaringKind::Await)
56 self.diverges.set(Diverges::WarnedAlways);
58 debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind);
60 let msg = format!("unreachable {}", kind);
61 self.tcx().struct_span_lint_hir(
62 lint::builtin::UNREACHABLE_CODE,
67 lint.span_label(span, &msg).span_label(
70 .unwrap_or("any code following this expression is unreachable"),
78 /// Resolves type and const variables in `ty` if possible. Unlike the infcx
79 /// version (resolve_vars_if_possible), this version will
80 /// also select obligations if it seems useful, in an effort
81 /// to get more type information.
82 pub(in super::super) fn resolve_vars_with_obligations(&self, ty: Ty<'tcx>) -> Ty<'tcx> {
83 self.resolve_vars_with_obligations_and_mutate_fulfillment(ty, |_| {})
86 #[instrument(skip(self, mutate_fulfillment_errors), level = "debug", ret)]
87 pub(in super::super) fn resolve_vars_with_obligations_and_mutate_fulfillment(
90 mutate_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
92 // No Infer()? Nothing needs doing.
93 if !ty.has_non_region_infer() {
94 debug!("no inference var, nothing needs doing");
98 // If `ty` is a type variable, see whether we already know what it is.
99 ty = self.resolve_vars_if_possible(ty);
100 if !ty.has_non_region_infer() {
105 // If not, try resolving pending obligations as much as
106 // possible. This can help substantially when there are
107 // indirect dependencies that don't seem worth tracking
109 self.select_obligations_where_possible(mutate_fulfillment_errors);
110 self.resolve_vars_if_possible(ty)
113 pub(in super::super) fn record_deferred_call_resolution(
115 closure_def_id: LocalDefId,
116 r: DeferredCallResolution<'tcx>,
118 let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
119 deferred_call_resolutions.entry(closure_def_id).or_default().push(r);
122 pub(in super::super) fn remove_deferred_call_resolutions(
124 closure_def_id: LocalDefId,
125 ) -> Vec<DeferredCallResolution<'tcx>> {
126 let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
127 deferred_call_resolutions.remove(&closure_def_id).unwrap_or_default()
130 pub fn tag(&self) -> String {
131 format!("{:p}", self)
134 pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> {
135 self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| {
136 span_bug!(span, "no type for local variable {}", self.tcx.hir().node_to_string(nid))
141 pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) {
142 debug!("write_ty({:?}, {:?}) in fcx {}", id, self.resolve_vars_if_possible(ty), self.tag());
143 self.typeck_results.borrow_mut().node_types_mut().insert(id, ty);
145 if let Err(e) = ty.error_reported() {
146 self.set_tainted_by_errors(e);
150 pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) {
151 self.typeck_results.borrow_mut().field_indices_mut().insert(hir_id, index);
154 #[instrument(level = "debug", skip(self))]
155 pub(in super::super) fn write_resolution(
158 r: Result<(DefKind, DefId), ErrorGuaranteed>,
160 self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r);
163 #[instrument(level = "debug", skip(self))]
164 pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) {
165 self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id)));
166 self.write_substs(hir_id, method.substs);
169 pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) {
170 if !substs.is_empty() {
171 debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag());
173 self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs);
177 /// Given the substs that we just converted from the HIR, try to
178 /// canonicalize them and store them as user-given substitutions
179 /// (i.e., substitutions that must be respected by the NLL check).
181 /// This should be invoked **before any unifications have
182 /// occurred**, so that annotations like `Vec<_>` are preserved
184 #[instrument(skip(self), level = "debug")]
185 pub fn write_user_type_annotation_from_substs(
189 substs: SubstsRef<'tcx>,
190 user_self_ty: Option<UserSelfTy<'tcx>>,
192 debug!("fcx {}", self.tag());
194 if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) {
195 let canonicalized = self.canonicalize_user_type_annotation(UserType::TypeOf(
197 UserSubsts { substs, user_self_ty },
199 debug!(?canonicalized);
200 self.write_user_type_annotation(hir_id, canonicalized);
204 #[instrument(skip(self), level = "debug")]
205 pub fn write_user_type_annotation(
208 canonical_user_type_annotation: CanonicalUserType<'tcx>,
210 debug!("fcx {}", self.tag());
212 if !canonical_user_type_annotation.is_identity() {
215 .user_provided_types_mut()
216 .insert(hir_id, canonical_user_type_annotation);
218 debug!("skipping identity substs");
222 #[instrument(skip(self, expr), level = "debug")]
223 pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec<Adjustment<'tcx>>) {
224 debug!("expr = {:#?}", expr);
231 if let Adjust::NeverToAny = a.kind {
232 if a.target.is_ty_var() {
233 self.diverging_type_vars.borrow_mut().insert(a.target);
234 debug!("apply_adjustments: adding `{:?}` as diverging type var", a.target);
239 let autoborrow_mut = adj.iter().any(|adj| {
243 kind: Adjust::Borrow(AutoBorrow::Ref(_, AutoBorrowMutability::Mut { .. })),
249 match self.typeck_results.borrow_mut().adjustments_mut().entry(expr.hir_id) {
250 Entry::Vacant(entry) => {
253 Entry::Occupied(mut entry) => {
254 debug!(" - composing on top of {:?}", entry.get());
255 match (&entry.get()[..], &adj[..]) {
256 // Applying any adjustment on top of a NeverToAny
257 // is a valid NeverToAny adjustment, because it can't
259 (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return,
262 Adjustment { kind: Adjust::Deref(_), .. },
263 Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. },
266 Adjustment { kind: Adjust::Deref(_), .. },
267 .., // Any following adjustments are allowed.
270 // A reborrow has no effect before a dereference.
272 // FIXME: currently we never try to compose autoderefs
273 // and ReifyFnPointer/UnsafeFnPointer, but we could.
275 self.tcx.sess.delay_span_bug(
278 "while adjusting {:?}, can't compose {:?} and {:?}",
286 *entry.get_mut() = adj;
290 // If there is an mutable auto-borrow, it is equivalent to `&mut <expr>`.
291 // In this case implicit use of `Deref` and `Index` within `<expr>` should
292 // instead be `DerefMut` and `IndexMut`, so fix those up.
294 self.convert_place_derefs_to_mutable(expr);
298 /// Instantiates and normalizes the bounds for a given item
299 pub(in super::super) fn instantiate_bounds(
303 substs: SubstsRef<'tcx>,
304 ) -> (ty::InstantiatedPredicates<'tcx>, Vec<Span>) {
305 let bounds = self.tcx.predicates_of(def_id);
306 let spans: Vec<Span> = bounds.predicates.iter().map(|(_, span)| *span).collect();
307 let result = bounds.instantiate(self.tcx, substs);
308 let result = self.normalize(span, result);
310 "instantiate_bounds(bounds={:?}, substs={:?}) = {:?}, {:?}",
311 bounds, substs, result, spans,
316 pub(in super::super) fn normalize<T>(&self, span: Span, value: T) -> T
318 T: TypeFoldable<'tcx>,
320 self.register_infer_ok_obligations(
321 self.at(&self.misc(span), self.param_env).normalize(value),
325 pub fn require_type_meets(
329 code: traits::ObligationCauseCode<'tcx>,
332 self.register_bound(ty, def_id, traits::ObligationCause::new(span, self.body_id, code));
335 pub fn require_type_is_sized(
339 code: traits::ObligationCauseCode<'tcx>,
341 if !ty.references_error() {
342 let lang_item = self.tcx.require_lang_item(LangItem::Sized, None);
343 self.require_type_meets(ty, span, code, lang_item);
347 pub fn require_type_is_sized_deferred(
351 code: traits::ObligationCauseCode<'tcx>,
353 if !ty.references_error() {
354 self.deferred_sized_obligations.borrow_mut().push((ty, span, code));
358 pub fn register_bound(
362 cause: traits::ObligationCause<'tcx>,
364 if !ty.references_error() {
365 self.fulfillment_cx.borrow_mut().register_bound(
375 pub fn handle_raw_ty(&self, span: Span, ty: Ty<'tcx>) -> RawTy<'tcx> {
376 RawTy { raw: ty, normalized: self.normalize(span, ty) }
379 pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> RawTy<'tcx> {
380 let t = self.astconv().ast_ty_to_ty(ast_t);
381 self.register_wf_obligation(t.into(), ast_t.span, traits::WellFormed(None));
382 self.handle_raw_ty(ast_t.span, t)
385 pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
386 let ty = self.to_ty(ast_ty);
387 debug!("to_ty_saving_user_provided_ty: ty={:?}", ty);
389 if Self::can_contain_user_lifetime_bounds(ty.raw) {
390 let c_ty = self.canonicalize_response(UserType::Ty(ty.raw));
391 debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty);
392 self.typeck_results.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty);
398 pub(super) fn user_substs_for_adt(ty: RawTy<'tcx>) -> UserSubsts<'tcx> {
399 match (ty.raw.kind(), ty.normalized.kind()) {
400 (ty::Adt(_, substs), _) => UserSubsts { substs, user_self_ty: None },
401 (_, ty::Adt(adt, substs)) => UserSubsts {
403 user_self_ty: Some(UserSelfTy { impl_def_id: adt.did(), self_ty: ty.raw }),
405 _ => bug!("non-adt type {:?}", ty),
409 pub fn array_length_to_const(&self, length: &hir::ArrayLen) -> ty::Const<'tcx> {
411 &hir::ArrayLen::Infer(_, span) => self.ct_infer(self.tcx.types.usize, None, span),
412 hir::ArrayLen::Body(anon_const) => {
413 let span = self.tcx.def_span(anon_const.def_id);
414 let c = ty::Const::from_anon_const(self.tcx, anon_const.def_id);
415 self.register_wf_obligation(c.into(), span, ObligationCauseCode::WellFormed(None));
416 self.normalize(span, c)
421 pub fn const_arg_to_const(
423 ast_c: &hir::AnonConst,
425 ) -> ty::Const<'tcx> {
427 ty::WithOptConstParam { did: ast_c.def_id, const_param_did: Some(param_def_id) };
428 let c = ty::Const::from_opt_const_arg_anon_const(self.tcx, const_def);
429 self.register_wf_obligation(
431 self.tcx.hir().span(ast_c.hir_id),
432 ObligationCauseCode::WellFormed(None),
437 // If the type given by the user has free regions, save it for later, since
438 // NLL would like to enforce those. Also pass in types that involve
439 // projections, since those can resolve to `'static` bounds (modulo #54940,
440 // which hopefully will be fixed by the time you see this comment, dear
441 // reader, although I have my doubts). Also pass in types with inference
442 // types, because they may be repeated. Other sorts of things are already
443 // sufficiently enforced with erased regions. =)
444 fn can_contain_user_lifetime_bounds<T>(t: T) -> bool
446 T: TypeVisitable<'tcx>,
448 t.has_free_regions() || t.has_projections() || t.has_infer_types()
451 pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> {
452 match self.typeck_results.borrow().node_types().get(id) {
454 None if let Some(e) = self.tainted_by_errors() => self.tcx.ty_error_with_guaranteed(e),
457 "no type for node {}: {} in fcx {}",
459 self.tcx.hir().node_to_string(id),
466 pub fn node_ty_opt(&self, id: hir::HirId) -> Option<Ty<'tcx>> {
467 match self.typeck_results.borrow().node_types().get(id) {
469 None if let Some(e) = self.tainted_by_errors() => Some(self.tcx.ty_error_with_guaranteed(e)),
474 /// Registers an obligation for checking later, during regionck, that `arg` is well-formed.
475 pub fn register_wf_obligation(
477 arg: ty::GenericArg<'tcx>,
479 code: traits::ObligationCauseCode<'tcx>,
481 // WF obligations never themselves fail, so no real need to give a detailed cause:
482 let cause = traits::ObligationCause::new(span, self.body_id, code);
483 self.register_predicate(traits::Obligation::new(
487 ty::Binder::dummy(ty::PredicateKind::WellFormed(arg)),
491 /// Registers obligations that all `substs` are well-formed.
492 pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr<'_>) {
493 for arg in substs.iter().filter(|arg| {
494 matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..))
496 self.register_wf_obligation(arg, expr.span, traits::WellFormed(None));
500 // FIXME(arielb1): use this instead of field.ty everywhere
501 // Only for fields! Returns <none> for methods>
502 // Indifferent to privacy flags
506 field: &'tcx ty::FieldDef,
507 substs: SubstsRef<'tcx>,
509 self.normalize(span, field.ty(self.tcx, substs))
512 pub(in super::super) fn resolve_rvalue_scopes(&self, def_id: DefId) {
513 let scope_tree = self.tcx.region_scope_tree(def_id);
514 let rvalue_scopes = { rvalue_scopes::resolve_rvalue_scopes(self, &scope_tree, def_id) };
515 let mut typeck_results = self.inh.typeck_results.borrow_mut();
516 typeck_results.rvalue_scopes = rvalue_scopes;
519 pub(in super::super) fn resolve_generator_interiors(&self, def_id: DefId) {
520 let mut generators = self.deferred_generator_interiors.borrow_mut();
521 for (body_id, interior, kind) in generators.drain(..) {
522 self.select_obligations_where_possible(|_| {});
523 crate::generator_interior::resolve_interior(self, def_id, body_id, interior, kind);
527 #[instrument(skip(self), level = "debug")]
528 pub(in super::super) fn select_all_obligations_or_error(&self) {
529 let mut errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self);
531 if !errors.is_empty() {
532 self.adjust_fulfillment_errors_for_expr_obligation(&mut errors);
533 self.err_ctxt().report_fulfillment_errors(&errors, self.inh.body_id);
537 /// Select as many obligations as we can at present.
538 pub(in super::super) fn select_obligations_where_possible(
540 mutate_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
542 let mut result = self.fulfillment_cx.borrow_mut().select_where_possible(self);
543 if !result.is_empty() {
544 mutate_fulfillment_errors(&mut result);
545 self.adjust_fulfillment_errors_for_expr_obligation(&mut result);
546 self.err_ctxt().report_fulfillment_errors(&result, self.inh.body_id);
550 /// For the overloaded place expressions (`*x`, `x[3]`), the trait
551 /// returns a type of `&T`, but the actual type we assign to the
552 /// *expression* is `T`. So this function just peels off the return
553 /// type by one layer to yield `T`.
554 pub(in super::super) fn make_overloaded_place_return_type(
556 method: MethodCallee<'tcx>,
557 ) -> ty::TypeAndMut<'tcx> {
558 // extract method return type, which will be &T;
559 let ret_ty = method.sig.output();
561 // method returns &T, but the type as visible to user is T, so deref
562 ret_ty.builtin_deref(true).unwrap()
565 #[instrument(skip(self), level = "debug")]
566 fn self_type_matches_expected_vid(&self, self_ty: Ty<'tcx>, expected_vid: ty::TyVid) -> bool {
567 let self_ty = self.shallow_resolve(self_ty);
570 match *self_ty.kind() {
571 ty::Infer(ty::TyVar(found_vid)) => {
572 // FIXME: consider using `sub_root_var` here so we
573 // can see through subtyping.
574 let found_vid = self.root_var(found_vid);
575 debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid);
576 expected_vid == found_vid
582 #[instrument(skip(self), level = "debug")]
583 pub(in super::super) fn obligations_for_self_ty<'b>(
586 ) -> impl DoubleEndedIterator<Item = traits::PredicateObligation<'tcx>> + Captures<'tcx> + 'b
588 // FIXME: consider using `sub_root_var` here so we
589 // can see through subtyping.
590 let ty_var_root = self.root_var(self_ty);
591 trace!("pending_obligations = {:#?}", self.fulfillment_cx.borrow().pending_obligations());
593 self.fulfillment_cx.borrow().pending_obligations().into_iter().filter_map(
594 move |obligation| match &obligation.predicate.kind().skip_binder() {
595 ty::PredicateKind::Clause(ty::Clause::Projection(data))
596 if self.self_type_matches_expected_vid(
597 data.projection_ty.self_ty(),
603 ty::PredicateKind::Clause(ty::Clause::Trait(data))
604 if self.self_type_matches_expected_vid(data.self_ty(), ty_var_root) =>
609 ty::PredicateKind::Clause(ty::Clause::Trait(..))
610 | ty::PredicateKind::Clause(ty::Clause::Projection(..))
611 | ty::PredicateKind::Subtype(..)
612 | ty::PredicateKind::Coerce(..)
613 | ty::PredicateKind::Clause(ty::Clause::RegionOutlives(..))
614 | ty::PredicateKind::Clause(ty::Clause::TypeOutlives(..))
615 | ty::PredicateKind::WellFormed(..)
616 | ty::PredicateKind::ObjectSafe(..)
617 | ty::PredicateKind::ConstEvaluatable(..)
618 | ty::PredicateKind::ConstEquate(..)
619 // N.B., this predicate is created by breaking down a
620 // `ClosureType: FnFoo()` predicate, where
621 // `ClosureType` represents some `Closure`. It can't
622 // possibly be referring to the current closure,
623 // because we haven't produced the `Closure` for
624 // this closure yet; this is exactly why the other
625 // code is looking for a self type of an unresolved
626 // inference variable.
627 | ty::PredicateKind::ClosureKind(..)
628 | ty::PredicateKind::Ambiguous
629 | ty::PredicateKind::TypeWellFormedFromEnv(..) => None,
634 pub(in super::super) fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool {
635 let sized_did = self.tcx.lang_items().sized_trait();
636 self.obligations_for_self_ty(self_ty).any(|obligation| {
637 match obligation.predicate.kind().skip_binder() {
638 ty::PredicateKind::Clause(ty::Clause::Trait(data)) => {
639 Some(data.def_id()) == sized_did
646 pub(in super::super) fn err_args(&self, len: usize) -> Vec<Ty<'tcx>> {
647 vec![self.tcx.ty_error(); len]
650 /// Unifies the output type with the expected type early, for more coercions
651 /// and forward type information on the input expressions.
652 #[instrument(skip(self, call_span), level = "debug")]
653 pub(in super::super) fn expected_inputs_for_expected_output(
656 expected_ret: Expectation<'tcx>,
657 formal_ret: Ty<'tcx>,
658 formal_args: &[Ty<'tcx>],
659 ) -> Option<Vec<Ty<'tcx>>> {
660 let formal_ret = self.resolve_vars_with_obligations(formal_ret);
661 let ret_ty = expected_ret.only_has_type(self)?;
663 // HACK(oli-obk): This is a hack to keep RPIT and TAIT in sync wrt their behaviour.
664 // Without it, the inference
665 // variable will get instantiated with the opaque type. The inference variable often
666 // has various helpful obligations registered for it that help closures figure out their
667 // signature. If we infer the inference var to the opaque type, the closure won't be able
668 // to find those obligations anymore, and it can't necessarily find them from the opaque
669 // type itself. We could be more powerful with inference if we *combined* the obligations
670 // so that we got both the obligations from the opaque type and the ones from the inference
671 // variable. That will accept more code than we do right now, so we need to carefully consider
673 // Note: this check is pessimistic, as the inference type could be matched with something other
674 // than the opaque type, but then we need a new `TypeRelation` just for this specific case and
675 // can't re-use `sup` below.
676 // See tests/ui/impl-trait/hidden-type-is-opaque.rs and
677 // tests/ui/impl-trait/hidden-type-is-opaque-2.rs for examples that hit this path.
678 if formal_ret.has_infer_types() {
679 for ty in ret_ty.walk() {
680 if let ty::subst::GenericArgKind::Type(ty) = ty.unpack()
681 && let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = *ty.kind()
682 && let Some(def_id) = def_id.as_local()
683 && self.opaque_type_origin(def_id, DUMMY_SP).is_some() {
689 let expect_args = self
690 .fudge_inference_if_ok(|| {
691 let ocx = ObligationCtxt::new_in_snapshot(self);
693 // Attempt to apply a subtyping relationship between the formal
694 // return type (likely containing type variables if the function
695 // is polymorphic) and the expected return type.
696 // No argument expectations are produced if unification fails.
697 let origin = self.misc(call_span);
698 ocx.sup(&origin, self.param_env, ret_ty, formal_ret)?;
699 if !ocx.select_where_possible().is_empty() {
700 return Err(TypeError::Mismatch);
703 // Record all the argument types, with the substitutions
704 // produced from the above subtyping unification.
705 Ok(Some(formal_args.iter().map(|&ty| self.resolve_vars_if_possible(ty)).collect()))
707 .unwrap_or_default();
708 debug!(?formal_args, ?formal_ret, ?expect_args, ?expected_ret);
712 pub(in super::super) fn resolve_lang_item_path(
714 lang_item: hir::LangItem,
717 expr_hir_id: Option<hir::HirId>,
718 ) -> (Res, Ty<'tcx>) {
719 let def_id = self.tcx.require_lang_item(lang_item, Some(span));
720 let def_kind = self.tcx.def_kind(def_id);
722 let item_ty = if let DefKind::Variant = def_kind {
723 self.tcx.bound_type_of(self.tcx.parent(def_id))
725 self.tcx.bound_type_of(def_id)
727 let substs = self.fresh_substs_for_item(span, def_id);
728 let ty = item_ty.subst(self.tcx, substs);
730 self.write_resolution(hir_id, Ok((def_kind, def_id)));
732 let code = match lang_item {
733 hir::LangItem::IntoFutureIntoFuture => {
734 Some(ObligationCauseCode::AwaitableExpr(expr_hir_id))
736 hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => {
737 Some(ObligationCauseCode::ForLoopIterator)
739 hir::LangItem::TryTraitFromOutput
740 | hir::LangItem::TryTraitFromResidual
741 | hir::LangItem::TryTraitBranch => Some(ObligationCauseCode::QuestionMark),
744 if let Some(code) = code {
745 self.add_required_obligations_with_code(span, def_id, substs, move |_, _| code.clone());
747 self.add_required_obligations_for_hir(span, def_id, substs, hir_id);
750 (Res::Def(def_kind, def_id), ty)
753 /// Resolves an associated value path into a base type and associated constant, or method
754 /// resolution. The newly resolved definition is written into `type_dependent_defs`.
755 pub fn resolve_ty_and_res_fully_qualified_call(
757 qpath: &'tcx QPath<'tcx>,
760 ) -> (Res, Option<RawTy<'tcx>>, &'tcx [hir::PathSegment<'tcx>]) {
762 "resolve_ty_and_res_fully_qualified_call: qpath={:?} hir_id={:?} span={:?}",
765 let (ty, qself, item_segment) = match *qpath {
766 QPath::Resolved(ref opt_qself, ref path) => {
769 opt_qself.as_ref().map(|qself| self.to_ty(qself)),
773 QPath::TypeRelative(ref qself, ref segment) => {
774 // Don't use `self.to_ty`, since this will register a WF obligation.
775 // If we're trying to call a non-existent method on a trait
776 // (e.g. `MyTrait::missing_method`), then resolution will
777 // give us a `QPath::TypeRelative` with a trait object as
778 // `qself`. In that case, we want to avoid registering a WF obligation
779 // for `dyn MyTrait`, since we don't actually need the trait
780 // to be object-safe.
781 // We manually call `register_wf_obligation` in the success path
783 let ty = self.astconv().ast_ty_to_ty_in_path(qself);
784 (self.handle_raw_ty(span, ty), qself, segment)
786 QPath::LangItem(..) => {
787 bug!("`resolve_ty_and_res_fully_qualified_call` called on `LangItem`")
790 if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id)
792 self.register_wf_obligation(ty.raw.into(), qself.span, traits::WellFormed(None));
793 // Return directly on cache hit. This is useful to avoid doubly reporting
794 // errors with default match binding modes. See #44614.
795 let def = cached_result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id));
796 return (def, Some(ty), slice::from_ref(&**item_segment));
798 let item_name = item_segment.ident;
800 .resolve_fully_qualified_call(span, item_name, ty.normalized, qself.span, hir_id)
802 let result = match error {
803 method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
804 _ => Err(ErrorGuaranteed::unchecked_claim_error_was_emitted()),
807 // If we have a path like `MyTrait::missing_method`, then don't register
808 // a WF obligation for `dyn MyTrait` when method lookup fails. Otherwise,
809 // register a WF obligation so that we can detect any additional
810 // errors in the self type.
811 if !(matches!(error, method::MethodError::NoMatch(_)) && ty.normalized.is_trait()) {
812 self.register_wf_obligation(
815 traits::WellFormed(None),
818 if item_name.name != kw::Empty {
819 if let Some(mut e) = self.report_method_error(
823 SelfSource::QPath(qself),
826 Expectation::NoExpectation,
835 self.register_wf_obligation(ty.raw.into(), qself.span, traits::WellFormed(None));
838 // Write back the new resolution.
839 self.write_resolution(hir_id, result);
841 result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
843 slice::from_ref(&**item_segment),
847 /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise.
848 pub(in super::super) fn get_node_fn_decl(
851 ) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident, bool)> {
853 Node::Item(&hir::Item { ident, kind: hir::ItemKind::Fn(ref sig, ..), .. }) => {
854 // This is less than ideal, it will not suggest a return type span on any
855 // method called `main`, regardless of whether it is actually the entry point,
856 // but it will still present it as the reason for the expected type.
857 Some((&sig.decl, ident, ident.name != sym::main))
859 Node::TraitItem(&hir::TraitItem {
861 kind: hir::TraitItemKind::Fn(ref sig, ..),
863 }) => Some((&sig.decl, ident, true)),
864 Node::ImplItem(&hir::ImplItem {
866 kind: hir::ImplItemKind::Fn(ref sig, ..),
868 }) => Some((&sig.decl, ident, false)),
873 /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a
874 /// suggestion can be made, `None` otherwise.
875 pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, bool)> {
876 // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or
877 // `while` before reaching it, as block tail returns are not available in them.
878 self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| {
879 let parent = self.tcx.hir().get(blk_id);
880 self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main))
884 pub(in super::super) fn note_internal_mutation_in_method(
886 err: &mut Diagnostic,
887 expr: &hir::Expr<'_>,
891 if found != self.tcx.types.unit {
894 if let ExprKind::MethodCall(path_segment, rcvr, ..) = expr.kind {
898 .expr_ty_adjusted_opt(rcvr)
899 .map_or(true, |ty| expected.peel_refs() != ty.peel_refs())
903 let mut sp = MultiSpan::from_span(path_segment.ident.span);
905 path_segment.ident.span,
907 "this call modifies {} in-place",
909 ExprKind::Path(QPath::Resolved(
911 hir::Path { segments: [segment], .. },
912 )) => format!("`{}`", segment.ident),
913 _ => "its receiver".to_string(),
919 "you probably want to use this value after calling the method...",
923 &format!("method `{}` modifies its receiver in-place", path_segment.ident),
925 err.note(&format!("...instead of the `()` output of method `{}`", path_segment.ident));
929 pub(in super::super) fn note_need_for_fn_pointer(
931 err: &mut Diagnostic,
935 let (sig, did, substs) = match (&expected.kind(), &found.kind()) {
936 (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => {
937 let sig1 = self.tcx.bound_fn_sig(*did1).subst(self.tcx, substs1);
938 let sig2 = self.tcx.bound_fn_sig(*did2).subst(self.tcx, substs2);
943 "different `fn` items always have unique types, even if their signatures are \
946 (sig1, *did1, substs1)
948 (ty::FnDef(did, substs), ty::FnPtr(sig2)) => {
949 let sig1 = self.tcx.bound_fn_sig(*did).subst(self.tcx, substs);
957 err.help(&format!("change the expected type to be function pointer `{}`", sig));
959 "if the expected type is due to type inference, cast the expected `fn` to a function \
960 pointer: `{} as {}`",
961 self.tcx.def_path_str_with_substs(did, substs),
966 // Instantiates the given path, which must refer to an item with the given
967 // number of type parameters and type.
968 #[instrument(skip(self, span), level = "debug")]
969 pub fn instantiate_value_path(
971 segments: &[hir::PathSegment<'_>],
972 self_ty: Option<RawTy<'tcx>>,
976 ) -> (Ty<'tcx>, Res) {
979 let path_segs = match res {
980 Res::Local(_) | Res::SelfCtor(_) => vec![],
981 Res::Def(kind, def_id) => self.astconv().def_ids_for_value_path_segments(
983 self_ty.map(|ty| ty.raw),
988 _ => bug!("instantiate_value_path on {:?}", res),
991 let mut user_self_ty = None;
992 let mut is_alias_variant_ctor = false;
994 Res::Def(DefKind::Ctor(CtorOf::Variant, _), _)
995 if let Some(self_ty) = self_ty =>
997 let adt_def = self_ty.normalized.ty_adt_def().unwrap();
998 user_self_ty = Some(UserSelfTy { impl_def_id: adt_def.did(), self_ty: self_ty.raw });
999 is_alias_variant_ctor = true;
1001 Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => {
1002 let assoc_item = tcx.associated_item(def_id);
1003 let container = assoc_item.container;
1004 let container_id = assoc_item.container_id(tcx);
1005 debug!(?def_id, ?container, ?container_id);
1007 ty::TraitContainer => {
1008 callee::check_legal_trait_for_method_call(tcx, span, None, span, container_id)
1010 ty::ImplContainer => {
1011 if segments.len() == 1 {
1012 // `<T>::assoc` will end up here, and so
1013 // can `T::assoc`. It this came from an
1014 // inherent impl, we need to record the
1015 // `T` for posterity (see `UserSelfTy` for
1017 let self_ty = self_ty.expect("UFCS sugared assoc missing Self").raw;
1018 user_self_ty = Some(UserSelfTy { impl_def_id: container_id, self_ty });
1026 // Now that we have categorized what space the parameters for each
1027 // segment belong to, let's sort out the parameters that the user
1028 // provided (if any) into their appropriate spaces. We'll also report
1029 // errors if type parameters are provided in an inappropriate place.
1031 let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect();
1032 let generics_has_err = self.astconv().prohibit_generics(
1033 segments.iter().enumerate().filter_map(|(index, seg)| {
1034 if !generic_segs.contains(&index) || is_alias_variant_ctor {
1043 if let Res::Local(hid) = res {
1044 let ty = self.local_ty(span, hid).decl_ty;
1045 let ty = self.normalize(span, ty);
1046 self.write_ty(hir_id, ty);
1050 if generics_has_err {
1051 // Don't try to infer type parameters when prohibited generic arguments were given.
1052 user_self_ty = None;
1055 // Now we have to compare the types that the user *actually*
1056 // provided against the types that were *expected*. If the user
1057 // did not provide any types, then we want to substitute inference
1058 // variables. If the user provided some types, we may still need
1059 // to add defaults. If the user provided *too many* types, that's
1062 let mut infer_args_for_err = FxHashSet::default();
1064 let mut explicit_late_bound = ExplicitLateBound::No;
1065 for &PathSeg(def_id, index) in &path_segs {
1066 let seg = &segments[index];
1067 let generics = tcx.generics_of(def_id);
1069 // Argument-position `impl Trait` is treated as a normal generic
1070 // parameter internally, but we don't allow users to specify the
1071 // parameter's value explicitly, so we have to do some error-
1073 let arg_count = check_generic_arg_count_for_call(
1082 if let ExplicitLateBound::Yes = arg_count.explicit_late_bound {
1083 explicit_late_bound = ExplicitLateBound::Yes;
1086 if let Err(GenericArgCountMismatch { reported: Some(e), .. }) = arg_count.correct {
1087 infer_args_for_err.insert(index);
1088 self.set_tainted_by_errors(e); // See issue #53251.
1092 let has_self = path_segs
1094 .map(|PathSeg(def_id, _)| tcx.generics_of(*def_id).has_self)
1097 let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res {
1098 let ty = self.handle_raw_ty(span, tcx.at(span).type_of(impl_def_id));
1099 match ty.normalized.ty_adt_def() {
1100 Some(adt_def) if adt_def.has_ctor() => {
1101 let (ctor_kind, ctor_def_id) = adt_def.non_enum_variant().ctor.unwrap();
1102 let new_res = Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
1103 let user_substs = Self::user_substs_for_adt(ty);
1104 user_self_ty = user_substs.user_self_ty;
1105 (new_res, Some(user_substs.substs))
1108 let mut err = tcx.sess.struct_span_err(
1110 "the `Self` constructor can only be used with tuple or unit structs",
1112 if let Some(adt_def) = ty.normalized.ty_adt_def() {
1113 match adt_def.adt_kind() {
1115 err.help("did you mean to use one of the enum's variants?");
1117 AdtKind::Struct | AdtKind::Union => {
1118 err.span_suggestion(
1120 "use curly brackets",
1121 "Self { /* fields */ }",
1122 Applicability::HasPlaceholders,
1127 let reported = err.emit();
1128 return (tcx.ty_error_with_guaranteed(reported), res);
1134 let def_id = res.def_id();
1136 let arg_count = GenericArgCountResult {
1137 explicit_late_bound,
1138 correct: if infer_args_for_err.is_empty() {
1141 Err(GenericArgCountMismatch::default())
1145 struct CreateCtorSubstsContext<'a, 'tcx> {
1146 fcx: &'a FnCtxt<'a, 'tcx>,
1148 path_segs: &'a [PathSeg],
1149 infer_args_for_err: &'a FxHashSet<usize>,
1150 segments: &'a [hir::PathSegment<'a>],
1152 impl<'tcx, 'a> CreateSubstsForGenericArgsCtxt<'a, 'tcx> for CreateCtorSubstsContext<'a, 'tcx> {
1156 ) -> (Option<&'a hir::GenericArgs<'a>>, bool) {
1157 if let Some(&PathSeg(_, index)) =
1158 self.path_segs.iter().find(|&PathSeg(did, _)| *did == def_id)
1160 // If we've encountered an `impl Trait`-related error, we're just
1161 // going to infer the arguments for better error messages.
1162 if !self.infer_args_for_err.contains(&index) {
1163 // Check whether the user has provided generic arguments.
1164 if let Some(ref data) = self.segments[index].args {
1165 return (Some(data), self.segments[index].infer_args);
1168 return (None, self.segments[index].infer_args);
1176 param: &ty::GenericParamDef,
1177 arg: &GenericArg<'_>,
1178 ) -> ty::GenericArg<'tcx> {
1179 match (¶m.kind, arg) {
1180 (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
1181 self.fcx.astconv().ast_region_to_region(lt, Some(param)).into()
1183 (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
1184 self.fcx.to_ty(ty).raw.into()
1186 (GenericParamDefKind::Const { .. }, GenericArg::Const(ct)) => {
1187 self.fcx.const_arg_to_const(&ct.value, param.def_id).into()
1189 (GenericParamDefKind::Type { .. }, GenericArg::Infer(inf)) => {
1190 self.fcx.ty_infer(Some(param), inf.span).into()
1192 (GenericParamDefKind::Const { .. }, GenericArg::Infer(inf)) => {
1193 let tcx = self.fcx.tcx();
1194 self.fcx.ct_infer(tcx.type_of(param.def_id), Some(param), inf.span).into()
1196 _ => unreachable!(),
1202 substs: Option<&[ty::GenericArg<'tcx>]>,
1203 param: &ty::GenericParamDef,
1205 ) -> ty::GenericArg<'tcx> {
1206 let tcx = self.fcx.tcx();
1208 GenericParamDefKind::Lifetime => {
1209 self.fcx.re_infer(Some(param), self.span).unwrap().into()
1211 GenericParamDefKind::Type { has_default, .. } => {
1212 if !infer_args && has_default {
1213 // If we have a default, then we it doesn't matter that we're not
1214 // inferring the type arguments: we provide the default where any
1216 tcx.bound_type_of(param.def_id).subst(tcx, substs.unwrap()).into()
1218 // If no type arguments were provided, we have to infer them.
1219 // This case also occurs as a result of some malformed input, e.g.
1220 // a lifetime argument being given instead of a type parameter.
1221 // Using inference instead of `Error` gives better error messages.
1222 self.fcx.var_for_def(self.span, param)
1225 GenericParamDefKind::Const { has_default } => {
1226 if !infer_args && has_default {
1227 tcx.bound_const_param_default(param.def_id)
1228 .subst(tcx, substs.unwrap())
1231 self.fcx.var_for_def(self.span, param)
1238 let substs_raw = self_ctor_substs.unwrap_or_else(|| {
1239 create_substs_for_generic_args(
1244 self_ty.map(|s| s.raw),
1246 &mut CreateCtorSubstsContext {
1249 path_segs: &path_segs,
1250 infer_args_for_err: &infer_args_for_err,
1256 // First, store the "user substs" for later.
1257 self.write_user_type_annotation_from_substs(hir_id, def_id, substs_raw, user_self_ty);
1259 // Normalize only after registering type annotations.
1260 let substs = self.normalize(span, substs_raw);
1262 self.add_required_obligations_for_hir(span, def_id, &substs, hir_id);
1264 // Substitute the values for the type parameters into the type of
1265 // the referenced item.
1266 let ty = tcx.bound_type_of(def_id);
1267 assert!(!substs.has_escaping_bound_vars());
1268 assert!(!ty.0.has_escaping_bound_vars());
1269 let ty_substituted = self.normalize(span, ty.subst(tcx, substs));
1271 if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
1272 // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
1273 // is inherent, there is no `Self` parameter; instead, the impl needs
1274 // type parameters, which we can infer by unifying the provided `Self`
1275 // with the substituted impl type.
1276 // This also occurs for an enum variant on a type alias.
1277 let impl_ty = self.normalize(span, tcx.bound_type_of(impl_def_id).subst(tcx, substs));
1278 let self_ty = self.normalize(span, self_ty);
1279 match self.at(&self.misc(span), self.param_env).eq(impl_ty, self_ty) {
1280 Ok(ok) => self.register_infer_ok_obligations(ok),
1282 self.tcx.sess.delay_span_bug(
1285 "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?",
1294 debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted);
1295 self.write_substs(hir_id, substs);
1297 (ty_substituted, res)
1300 /// Add all the obligations that are required, substituting and normalized appropriately.
1301 pub(crate) fn add_required_obligations_for_hir(
1305 substs: SubstsRef<'tcx>,
1308 self.add_required_obligations_with_code(span, def_id, substs, |idx, span| {
1309 if span.is_dummy() {
1310 ObligationCauseCode::ExprItemObligation(def_id, hir_id, idx)
1312 ObligationCauseCode::ExprBindingObligation(def_id, span, hir_id, idx)
1317 #[instrument(level = "debug", skip(self, code, span, substs))]
1318 fn add_required_obligations_with_code(
1322 substs: SubstsRef<'tcx>,
1323 code: impl Fn(usize, Span) -> ObligationCauseCode<'tcx>,
1325 let param_env = self.param_env;
1327 let remap = match self.tcx.def_kind(def_id) {
1328 // Associated consts have `Self: ~const Trait` bounds that should be satisfiable when
1329 // `Self: Trait` is satisfied because it does not matter whether the impl is `const`.
1330 // Therefore we have to remap the param env here to be non-const.
1331 hir::def::DefKind::AssocConst => true,
1332 hir::def::DefKind::AssocFn
1333 if self.tcx.def_kind(self.tcx.parent(def_id)) == hir::def::DefKind::Trait =>
1335 // N.B.: All callsites to this function involve checking a path expression.
1337 // When instantiating a trait method as a function item, it does not actually matter whether
1338 // the trait is `const` or not, or whether `where T: ~const Tr` needs to be satisfied as
1339 // `const`. If we were to introduce instantiating trait methods as `const fn`s, we would
1340 // check that after this, either via a bound `where F: ~const FnOnce` or when coercing to a
1341 // `const fn` pointer.
1343 // FIXME(fee1-dead) FIXME(const_trait_impl): update this doc when trait methods can satisfy
1344 // `~const FnOnce` or can be coerced to `const fn` pointer.
1349 let (bounds, _) = self.instantiate_bounds(span, def_id, &substs);
1351 for mut obligation in traits::predicates_for_generics(
1352 |idx, predicate_span| {
1353 traits::ObligationCause::new(span, self.body_id, code(idx, predicate_span))
1359 obligation = obligation.without_const(self.tcx);
1361 self.register_predicate(obligation);
1365 /// Resolves `typ` by a single level if `typ` is a type variable.
1366 /// If no resolution is possible, then an error is reported.
1367 /// Numeric inference variables may be left unresolved.
1368 pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
1369 let ty = self.resolve_vars_with_obligations(ty);
1370 if !ty.is_ty_var() {
1373 let e = self.tainted_by_errors().unwrap_or_else(|| {
1375 .emit_inference_failure_err((**self).body_id, sp, ty.into(), E0282, true)
1378 let err = self.tcx.ty_error_with_guaranteed(e);
1379 self.demand_suptype(sp, err, ty);
1384 pub(in super::super) fn with_breakable_ctxt<F: FnOnce() -> R, R>(
1387 ctxt: BreakableCtxt<'tcx>,
1389 ) -> (BreakableCtxt<'tcx>, R) {
1392 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
1393 index = enclosing_breakables.stack.len();
1394 enclosing_breakables.by_id.insert(id, index);
1395 enclosing_breakables.stack.push(ctxt);
1399 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
1400 debug_assert!(enclosing_breakables.stack.len() == index + 1);
1401 enclosing_breakables.by_id.remove(&id).expect("missing breakable context");
1402 enclosing_breakables.stack.pop().expect("missing breakable context")
1407 /// Instantiate a QueryResponse in a probe context, without a
1408 /// good ObligationCause.
1409 pub(in super::super) fn probe_instantiate_query_response(
1412 original_values: &OriginalQueryValues<'tcx>,
1413 query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
1414 ) -> InferResult<'tcx, Ty<'tcx>> {
1415 self.instantiate_query_response_and_region_obligations(
1416 &traits::ObligationCause::misc(span, self.body_id),
1423 /// Returns `true` if an expression is contained inside the LHS of an assignment expression.
1424 pub(in super::super) fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool {
1425 let mut contained_in_place = false;
1427 while let hir::Node::Expr(parent_expr) = self.tcx.hir().get_parent(expr_id) {
1428 match &parent_expr.kind {
1429 hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => {
1430 if lhs.hir_id == expr_id {
1431 contained_in_place = true;
1437 expr_id = parent_expr.hir_id;