2 AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch,
3 GenericArgCountResult, IsMethodCall, PathSeg,
5 use crate::check::callee::{self, DeferredCallResolution};
6 use crate::check::method::{self, MethodCallee, SelfSource};
7 use crate::check::{BreakableCtxt, Diverges, Expectation, FnCtxt, LocalTy};
9 use rustc_data_structures::captures::Captures;
10 use rustc_data_structures::fx::FxHashSet;
11 use rustc_errors::{Applicability, Diagnostic, ErrorGuaranteed};
13 use rustc_hir::def::{CtorOf, DefKind, Res};
14 use rustc_hir::def_id::DefId;
15 use rustc_hir::lang_items::LangItem;
16 use rustc_hir::{ExprKind, GenericArg, Node, QPath};
17 use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
18 use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
19 use rustc_infer::infer::{InferOk, InferResult};
20 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
21 use rustc_middle::ty::fold::TypeFoldable;
22 use rustc_middle::ty::subst::{
23 self, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSelfTy, UserSubsts,
25 use rustc_middle::ty::{
26 self, AdtKind, CanonicalUserType, DefIdTree, GenericParamDefKind, ToPolyTraitRef, ToPredicate,
29 use rustc_session::lint;
30 use rustc_span::hygiene::DesugaringKind;
31 use rustc_span::source_map::{original_sp, DUMMY_SP};
32 use rustc_span::symbol::{kw, sym, Ident};
33 use rustc_span::{self, BytePos, MultiSpan, Span};
34 use rustc_trait_selection::infer::InferCtxtExt as _;
35 use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
36 use rustc_trait_selection::traits::{
37 self, ObligationCause, ObligationCauseCode, StatementAsExpression, TraitEngine, TraitEngineExt,
41 use std::collections::hash_map::Entry;
45 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
46 /// Produces warning on the given node, if the current point in the
47 /// function is unreachable, and there hasn't been another warning.
48 pub(in super::super) fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) {
49 // FIXME: Combine these two 'if' expressions into one once
50 // let chains are implemented
51 if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() {
52 // If span arose from a desugaring of `if` or `while`, then it is the condition itself,
53 // which diverges, that we are about to lint on. This gives suboptimal diagnostics.
54 // Instead, stop here so that the `if`- or `while`-expression's block is linted instead.
55 if !span.is_desugaring(DesugaringKind::CondTemporary)
56 && !span.is_desugaring(DesugaringKind::Async)
57 && !orig_span.is_desugaring(DesugaringKind::Await)
59 self.diverges.set(Diverges::WarnedAlways);
61 debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind);
63 self.tcx().struct_span_lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, |lint| {
64 let msg = format!("unreachable {}", kind);
66 .span_label(span, &msg)
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")]
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_infer_types_or_consts() {
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_infer_types_or_consts() {
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(false, mutate_fulfillment_errors);
110 ty = self.resolve_vars_if_possible(ty);
116 pub(in super::super) fn record_deferred_call_resolution(
118 closure_def_id: DefId,
119 r: DeferredCallResolution<'tcx>,
121 let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
122 deferred_call_resolutions.entry(closure_def_id).or_default().push(r);
125 pub(in super::super) fn remove_deferred_call_resolutions(
127 closure_def_id: DefId,
128 ) -> Vec<DeferredCallResolution<'tcx>> {
129 let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
130 deferred_call_resolutions.remove(&closure_def_id).unwrap_or_default()
133 pub fn tag(&self) -> String {
134 format!("{:p}", self)
137 pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> {
138 self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| {
139 span_bug!(span, "no type for local variable {}", self.tcx.hir().node_to_string(nid))
144 pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) {
145 debug!("write_ty({:?}, {:?}) in fcx {}", id, self.resolve_vars_if_possible(ty), self.tag());
146 self.typeck_results.borrow_mut().node_types_mut().insert(id, ty);
148 if ty.references_error() {
149 self.has_errors.set(true);
150 self.set_tainted_by_errors();
154 pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) {
155 self.typeck_results.borrow_mut().field_indices_mut().insert(hir_id, index);
158 pub(in super::super) fn write_resolution(
161 r: Result<(DefKind, DefId), ErrorGuaranteed>,
163 self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r);
166 pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) {
167 debug!("write_method_call(hir_id={:?}, method={:?})", hir_id, method);
168 self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id)));
169 self.write_substs(hir_id, method.substs);
171 // When the method is confirmed, the `method.substs` includes
172 // parameters from not just the method, but also the impl of
173 // the method -- in particular, the `Self` type will be fully
174 // resolved. However, those are not something that the "user
175 // specified" -- i.e., those types come from the inferred type
176 // of the receiver, not something the user wrote. So when we
177 // create the user-substs, we want to replace those earlier
178 // types with just the types that the user actually wrote --
179 // that is, those that appear on the *method itself*.
181 // As an example, if the user wrote something like
182 // `foo.bar::<u32>(...)` -- the `Self` type here will be the
183 // type of `foo` (possibly adjusted), but we don't want to
184 // include that. We want just the `[_, u32]` part.
185 if !method.substs.is_empty() {
186 let method_generics = self.tcx.generics_of(method.def_id);
187 if !method_generics.params.is_empty() {
188 let user_type_annotation = self.infcx.probe(|_| {
189 let user_substs = UserSubsts {
190 substs: InternalSubsts::for_item(self.tcx, method.def_id, |param, _| {
191 let i = param.index as usize;
192 if i < method_generics.parent_count {
193 self.infcx.var_for_def(DUMMY_SP, param)
198 user_self_ty: None, // not relevant here
201 self.infcx.canonicalize_user_type_annotation(UserType::TypeOf(
207 debug!("write_method_call: user_type_annotation={:?}", user_type_annotation);
208 self.write_user_type_annotation(hir_id, user_type_annotation);
213 pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) {
214 if !substs.is_empty() {
215 debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag());
217 self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs);
221 /// Given the substs that we just converted from the HIR, try to
222 /// canonicalize them and store them as user-given substitutions
223 /// (i.e., substitutions that must be respected by the NLL check).
225 /// This should be invoked **before any unifications have
226 /// occurred**, so that annotations like `Vec<_>` are preserved
228 #[instrument(skip(self), level = "debug")]
229 pub fn write_user_type_annotation_from_substs(
233 substs: SubstsRef<'tcx>,
234 user_self_ty: Option<UserSelfTy<'tcx>>,
236 debug!("fcx {}", self.tag());
238 if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) {
239 let canonicalized = self.infcx.canonicalize_user_type_annotation(UserType::TypeOf(
241 UserSubsts { substs, user_self_ty },
243 debug!(?canonicalized);
244 self.write_user_type_annotation(hir_id, canonicalized);
248 #[instrument(skip(self), level = "debug")]
249 pub fn write_user_type_annotation(
252 canonical_user_type_annotation: CanonicalUserType<'tcx>,
254 debug!("fcx {}", self.tag());
256 if !canonical_user_type_annotation.is_identity() {
259 .user_provided_types_mut()
260 .insert(hir_id, canonical_user_type_annotation);
262 debug!("skipping identity substs");
266 #[instrument(skip(self, expr), level = "debug")]
267 pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec<Adjustment<'tcx>>) {
268 debug!("expr = {:#?}", expr);
275 if let Adjust::NeverToAny = a.kind {
276 if a.target.is_ty_var() {
277 self.diverging_type_vars.borrow_mut().insert(a.target);
278 debug!("apply_adjustments: adding `{:?}` as diverging type var", a.target);
283 let autoborrow_mut = adj.iter().any(|adj| {
287 kind: Adjust::Borrow(AutoBorrow::Ref(_, AutoBorrowMutability::Mut { .. })),
293 match self.typeck_results.borrow_mut().adjustments_mut().entry(expr.hir_id) {
294 Entry::Vacant(entry) => {
297 Entry::Occupied(mut entry) => {
298 debug!(" - composing on top of {:?}", entry.get());
299 match (&entry.get()[..], &adj[..]) {
300 // Applying any adjustment on top of a NeverToAny
301 // is a valid NeverToAny adjustment, because it can't
303 (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return,
306 Adjustment { kind: Adjust::Deref(_), .. },
307 Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. },
310 Adjustment { kind: Adjust::Deref(_), .. },
311 .., // Any following adjustments are allowed.
314 // A reborrow has no effect before a dereference.
316 // FIXME: currently we never try to compose autoderefs
317 // and ReifyFnPointer/UnsafeFnPointer, but we could.
319 "while adjusting {:?}, can't compose {:?} and {:?}",
325 *entry.get_mut() = adj;
329 // If there is an mutable auto-borrow, it is equivalent to `&mut <expr>`.
330 // In this case implicit use of `Deref` and `Index` within `<expr>` should
331 // instead be `DerefMut` and `IndexMut`, so fix those up.
333 self.convert_place_derefs_to_mutable(expr);
337 /// Basically whenever we are converting from a type scheme into
338 /// the fn body space, we always want to normalize associated
339 /// types as well. This function combines the two.
340 fn instantiate_type_scheme<T>(&self, span: Span, substs: SubstsRef<'tcx>, value: T) -> T
342 T: TypeFoldable<'tcx>,
344 debug!("instantiate_type_scheme(value={:?}, substs={:?})", value, substs);
345 let value = value.subst(self.tcx, substs);
346 let result = self.normalize_associated_types_in(span, value);
347 debug!("instantiate_type_scheme = {:?}", result);
351 /// As `instantiate_type_scheme`, but for the bounds found in a
352 /// generic type scheme.
353 pub(in super::super) fn instantiate_bounds(
357 substs: SubstsRef<'tcx>,
358 ) -> (ty::InstantiatedPredicates<'tcx>, Vec<Span>) {
359 let bounds = self.tcx.predicates_of(def_id);
360 let spans: Vec<Span> = bounds.predicates.iter().map(|(_, span)| *span).collect();
361 let result = bounds.instantiate(self.tcx, substs);
362 let result = self.normalize_associated_types_in(span, result);
364 "instantiate_bounds(bounds={:?}, substs={:?}) = {:?}, {:?}",
365 bounds, substs, result, spans,
370 /// Replaces the opaque types from the given value with type variables,
371 /// and records the `OpaqueTypeMap` for later use during writeback. See
372 /// `InferCtxt::instantiate_opaque_types` for more details.
373 #[instrument(skip(self, value_span), level = "debug")]
374 pub(in super::super) fn instantiate_opaque_types_from_value<T: TypeFoldable<'tcx>>(
379 self.register_infer_ok_obligations(self.instantiate_opaque_types(
387 /// Convenience method which tracks extra diagnostic information for normalization
388 /// that occurs as a result of WF checking. The `hir_id` is the `HirId` of the hir item
389 /// whose type is being wf-checked - this is used to construct a more precise span if
392 /// It is never necessary to call this method - calling `normalize_associated_types_in` will
393 /// just result in a slightly worse diagnostic span, and will still be sound.
394 pub(in super::super) fn normalize_associated_types_in_wf<T>(
401 T: TypeFoldable<'tcx>,
403 self.inh.normalize_associated_types_in_with_cause(
404 ObligationCause::new(span, self.body_id, ObligationCauseCode::WellFormed(Some(loc))),
410 pub(in super::super) fn normalize_associated_types_in<T>(&self, span: Span, value: T) -> T
412 T: TypeFoldable<'tcx>,
414 self.inh.normalize_associated_types_in(span, self.body_id, self.param_env, value)
417 pub(in super::super) fn normalize_associated_types_in_as_infer_ok<T>(
421 ) -> InferOk<'tcx, T>
423 T: TypeFoldable<'tcx>,
425 self.inh.partially_normalize_associated_types_in(
426 ObligationCause::misc(span, self.body_id),
432 pub(in super::super) fn normalize_op_associated_types_in_as_infer_ok<T>(
436 opt_input_expr: Option<&hir::Expr<'_>>,
437 ) -> InferOk<'tcx, T>
439 T: TypeFoldable<'tcx>,
441 self.inh.partially_normalize_associated_types_in(
442 ObligationCause::new(
446 rhs_span: opt_input_expr.map(|expr| expr.span),
447 is_lit: opt_input_expr
448 .map_or(false, |expr| matches!(expr.kind, ExprKind::Lit(_))),
456 pub fn require_type_meets(
460 code: traits::ObligationCauseCode<'tcx>,
463 self.register_bound(ty, def_id, traits::ObligationCause::new(span, self.body_id, code));
466 pub fn require_type_is_sized(
470 code: traits::ObligationCauseCode<'tcx>,
472 if !ty.references_error() {
473 let lang_item = self.tcx.require_lang_item(LangItem::Sized, None);
474 self.require_type_meets(ty, span, code, lang_item);
478 pub fn require_type_is_sized_deferred(
482 code: traits::ObligationCauseCode<'tcx>,
484 if !ty.references_error() {
485 self.deferred_sized_obligations.borrow_mut().push((ty, span, code));
489 pub fn register_bound(
493 cause: traits::ObligationCause<'tcx>,
495 if !ty.references_error() {
496 self.fulfillment_cx.borrow_mut().register_bound(
506 pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> Ty<'tcx> {
507 let t = <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_t);
508 self.register_wf_obligation(t.into(), ast_t.span, traits::MiscObligation);
512 pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
513 let ty = self.to_ty(ast_ty);
514 debug!("to_ty_saving_user_provided_ty: ty={:?}", ty);
516 if Self::can_contain_user_lifetime_bounds(ty) {
517 let c_ty = self.infcx.canonicalize_response(UserType::Ty(ty));
518 debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty);
519 self.typeck_results.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty);
525 pub fn array_length_to_const(&self, length: &hir::ArrayLen) -> ty::Const<'tcx> {
527 &hir::ArrayLen::Infer(_, span) => self.ct_infer(self.tcx.types.usize, None, span),
528 hir::ArrayLen::Body(anon_const) => self.to_const(anon_const),
532 pub fn to_const(&self, ast_c: &hir::AnonConst) -> ty::Const<'tcx> {
533 let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id);
534 let c = ty::Const::from_anon_const(self.tcx, const_def_id);
535 self.register_wf_obligation(
537 self.tcx.hir().span(ast_c.hir_id),
538 ObligationCauseCode::MiscObligation,
543 pub fn const_arg_to_const(
545 ast_c: &hir::AnonConst,
547 ) -> ty::Const<'tcx> {
548 let const_def = ty::WithOptConstParam {
549 did: self.tcx.hir().local_def_id(ast_c.hir_id),
550 const_param_did: Some(param_def_id),
552 let c = ty::Const::from_opt_const_arg_anon_const(self.tcx, const_def);
553 self.register_wf_obligation(
555 self.tcx.hir().span(ast_c.hir_id),
556 ObligationCauseCode::MiscObligation,
561 // If the type given by the user has free regions, save it for later, since
562 // NLL would like to enforce those. Also pass in types that involve
563 // projections, since those can resolve to `'static` bounds (modulo #54940,
564 // which hopefully will be fixed by the time you see this comment, dear
565 // reader, although I have my doubts). Also pass in types with inference
566 // types, because they may be repeated. Other sorts of things are already
567 // sufficiently enforced with erased regions. =)
568 fn can_contain_user_lifetime_bounds<T>(t: T) -> bool
570 T: TypeFoldable<'tcx>,
572 t.has_free_regions() || t.has_projections() || t.has_infer_types()
575 pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> {
576 match self.typeck_results.borrow().node_types().get(id) {
578 None if self.is_tainted_by_errors() => self.tcx.ty_error(),
581 "no type for node {}: {} in fcx {}",
583 self.tcx.hir().node_to_string(id),
590 pub fn node_ty_opt(&self, id: hir::HirId) -> Option<Ty<'tcx>> {
591 match self.typeck_results.borrow().node_types().get(id) {
593 None if self.is_tainted_by_errors() => Some(self.tcx.ty_error()),
598 /// Registers an obligation for checking later, during regionck, that `arg` is well-formed.
599 pub fn register_wf_obligation(
601 arg: subst::GenericArg<'tcx>,
603 code: traits::ObligationCauseCode<'tcx>,
605 // WF obligations never themselves fail, so no real need to give a detailed cause:
606 let cause = traits::ObligationCause::new(span, self.body_id, code);
607 self.register_predicate(traits::Obligation::new(
610 ty::Binder::dummy(ty::PredicateKind::WellFormed(arg)).to_predicate(self.tcx),
614 /// Registers obligations that all `substs` are well-formed.
615 pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr<'_>) {
616 for arg in substs.iter().filter(|arg| {
617 matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..))
619 self.register_wf_obligation(arg, expr.span, traits::MiscObligation);
623 // FIXME(arielb1): use this instead of field.ty everywhere
624 // Only for fields! Returns <none> for methods>
625 // Indifferent to privacy flags
629 field: &'tcx ty::FieldDef,
630 substs: SubstsRef<'tcx>,
632 self.normalize_associated_types_in(span, field.ty(self.tcx, substs))
635 pub(in super::super) fn resolve_generator_interiors(&self, def_id: DefId) {
636 let mut generators = self.deferred_generator_interiors.borrow_mut();
637 for (body_id, interior, kind) in generators.drain(..) {
638 self.select_obligations_where_possible(false, |_| {});
639 crate::check::generator_interior::resolve_interior(
640 self, def_id, body_id, interior, kind,
645 #[instrument(skip(self), level = "debug")]
646 pub(in super::super) fn select_all_obligations_or_error(&self) {
647 let errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self);
649 if !errors.is_empty() {
650 self.report_fulfillment_errors(&errors, self.inh.body_id, false);
654 /// Select as many obligations as we can at present.
655 pub(in super::super) fn select_obligations_where_possible(
657 fallback_has_occurred: bool,
658 mutate_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
660 let mut result = self.fulfillment_cx.borrow_mut().select_where_possible(self);
661 if !result.is_empty() {
662 mutate_fulfillment_errors(&mut result);
663 self.report_fulfillment_errors(&result, self.inh.body_id, fallback_has_occurred);
667 /// For the overloaded place expressions (`*x`, `x[3]`), the trait
668 /// returns a type of `&T`, but the actual type we assign to the
669 /// *expression* is `T`. So this function just peels off the return
670 /// type by one layer to yield `T`.
671 pub(in super::super) fn make_overloaded_place_return_type(
673 method: MethodCallee<'tcx>,
674 ) -> ty::TypeAndMut<'tcx> {
675 // extract method return type, which will be &T;
676 let ret_ty = method.sig.output();
678 // method returns &T, but the type as visible to user is T, so deref
679 ret_ty.builtin_deref(true).unwrap()
682 #[instrument(skip(self), level = "debug")]
683 fn self_type_matches_expected_vid(
685 trait_ref: ty::PolyTraitRef<'tcx>,
686 expected_vid: ty::TyVid,
688 let self_ty = self.shallow_resolve(trait_ref.skip_binder().self_ty());
691 match *self_ty.kind() {
692 ty::Infer(ty::TyVar(found_vid)) => {
693 // FIXME: consider using `sub_root_var` here so we
694 // can see through subtyping.
695 let found_vid = self.root_var(found_vid);
696 debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid);
697 expected_vid == found_vid
703 #[instrument(skip(self), level = "debug")]
704 pub(in super::super) fn obligations_for_self_ty<'b>(
707 ) -> impl Iterator<Item = (ty::PolyTraitRef<'tcx>, traits::PredicateObligation<'tcx>)>
710 // FIXME: consider using `sub_root_var` here so we
711 // can see through subtyping.
712 let ty_var_root = self.root_var(self_ty);
713 trace!("pending_obligations = {:#?}", self.fulfillment_cx.borrow().pending_obligations());
717 .pending_obligations()
719 .filter_map(move |obligation| {
720 let bound_predicate = obligation.predicate.kind();
721 match bound_predicate.skip_binder() {
722 ty::PredicateKind::Projection(data) => Some((
723 bound_predicate.rebind(data).required_poly_trait_ref(self.tcx),
726 ty::PredicateKind::Trait(data) => {
727 Some((bound_predicate.rebind(data).to_poly_trait_ref(), obligation))
729 ty::PredicateKind::Subtype(..) => None,
730 ty::PredicateKind::Coerce(..) => None,
731 ty::PredicateKind::RegionOutlives(..) => None,
732 ty::PredicateKind::TypeOutlives(..) => None,
733 ty::PredicateKind::WellFormed(..) => None,
734 ty::PredicateKind::ObjectSafe(..) => None,
735 ty::PredicateKind::ConstEvaluatable(..) => None,
736 ty::PredicateKind::ConstEquate(..) => None,
737 // N.B., this predicate is created by breaking down a
738 // `ClosureType: FnFoo()` predicate, where
739 // `ClosureType` represents some `Closure`. It can't
740 // possibly be referring to the current closure,
741 // because we haven't produced the `Closure` for
742 // this closure yet; this is exactly why the other
743 // code is looking for a self type of an unresolved
744 // inference variable.
745 ty::PredicateKind::ClosureKind(..) => None,
746 ty::PredicateKind::TypeWellFormedFromEnv(..) => None,
749 .filter(move |(tr, _)| self.self_type_matches_expected_vid(*tr, ty_var_root))
752 pub(in super::super) fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool {
753 self.obligations_for_self_ty(self_ty)
754 .any(|(tr, _)| Some(tr.def_id()) == self.tcx.lang_items().sized_trait())
757 pub(in super::super) fn err_args(&self, len: usize) -> Vec<Ty<'tcx>> {
758 vec![self.tcx.ty_error(); len]
761 /// Unifies the output type with the expected type early, for more coercions
762 /// and forward type information on the input expressions.
763 #[instrument(skip(self, call_span), level = "debug")]
764 pub(in super::super) fn expected_inputs_for_expected_output(
767 expected_ret: Expectation<'tcx>,
768 formal_ret: Ty<'tcx>,
769 formal_args: &[Ty<'tcx>],
771 let formal_ret = self.resolve_vars_with_obligations(formal_ret);
772 let Some(ret_ty) = expected_ret.only_has_type(self) else { return Vec::new() };
773 let expect_args = self
774 .fudge_inference_if_ok(|| {
775 // Attempt to apply a subtyping relationship between the formal
776 // return type (likely containing type variables if the function
777 // is polymorphic) and the expected return type.
778 // No argument expectations are produced if unification fails.
779 let origin = self.misc(call_span);
780 let ures = self.at(&origin, self.param_env).sup(ret_ty, formal_ret);
782 // FIXME(#27336) can't use ? here, Try::from_error doesn't default
783 // to identity so the resulting type is not constrained.
786 // Process any obligations locally as much as
787 // we can. We don't care if some things turn
788 // out unconstrained or ambiguous, as we're
789 // just trying to get hints here.
790 let errors = self.save_and_restore_in_snapshot_flag(|_| {
791 let mut fulfill = <dyn TraitEngine<'_>>::new(self.tcx);
792 for obligation in ok.obligations {
793 fulfill.register_predicate_obligation(self, obligation);
795 fulfill.select_where_possible(self)
798 if !errors.is_empty() {
802 Err(_) => return Err(()),
805 // Record all the argument types, with the substitutions
806 // produced from the above subtyping unification.
807 Ok(formal_args.iter().map(|&ty| self.resolve_vars_if_possible(ty)).collect())
809 .unwrap_or_default();
810 debug!(?formal_args, ?formal_ret, ?expect_args, ?expected_ret);
814 pub(in super::super) fn resolve_lang_item_path(
816 lang_item: hir::LangItem,
819 expr_hir_id: Option<hir::HirId>,
820 ) -> (Res, Ty<'tcx>) {
821 let def_id = self.tcx.require_lang_item(lang_item, Some(span));
822 let def_kind = self.tcx.def_kind(def_id);
824 let item_ty = if let DefKind::Variant = def_kind {
825 self.tcx.type_of(self.tcx.parent(def_id).expect("variant w/out parent"))
827 self.tcx.type_of(def_id)
829 let substs = self.infcx.fresh_substs_for_item(span, def_id);
830 let ty = item_ty.subst(self.tcx, substs);
832 self.write_resolution(hir_id, Ok((def_kind, def_id)));
833 self.add_required_obligations_with_code(
838 hir::LangItem::IntoFutureIntoFuture => {
839 ObligationCauseCode::AwaitableExpr(expr_hir_id)
841 hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => {
842 ObligationCauseCode::ForLoopIterator
844 hir::LangItem::TryTraitFromOutput
845 | hir::LangItem::TryTraitFromResidual
846 | hir::LangItem::TryTraitBranch => ObligationCauseCode::QuestionMark,
847 _ => traits::ItemObligation(def_id),
850 (Res::Def(def_kind, def_id), ty)
853 /// Resolves an associated value path into a base type and associated constant, or method
854 /// resolution. The newly resolved definition is written into `type_dependent_defs`.
855 pub fn resolve_ty_and_res_fully_qualified_call(
857 qpath: &'tcx QPath<'tcx>,
860 ) -> (Res, Option<Ty<'tcx>>, &'tcx [hir::PathSegment<'tcx>]) {
862 "resolve_ty_and_res_fully_qualified_call: qpath={:?} hir_id={:?} span={:?}",
865 let (ty, qself, item_segment) = match *qpath {
866 QPath::Resolved(ref opt_qself, ref path) => {
869 opt_qself.as_ref().map(|qself| self.to_ty(qself)),
873 QPath::TypeRelative(ref qself, ref segment) => {
874 // Don't use `self.to_ty`, since this will register a WF obligation.
875 // If we're trying to call a non-existent method on a trait
876 // (e.g. `MyTrait::missing_method`), then resolution will
877 // give us a `QPath::TypeRelative` with a trait object as
878 // `qself`. In that case, we want to avoid registering a WF obligation
879 // for `dyn MyTrait`, since we don't actually need the trait
880 // to be object-safe.
881 // We manually call `register_wf_obligation` in the success path
883 (<dyn AstConv<'_>>::ast_ty_to_ty_in_path(self, qself), qself, segment)
885 QPath::LangItem(..) => {
886 bug!("`resolve_ty_and_res_fully_qualified_call` called on `LangItem`")
889 if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id)
891 self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None));
892 // Return directly on cache hit. This is useful to avoid doubly reporting
893 // errors with default match binding modes. See #44614.
894 let def = cached_result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id));
895 return (def, Some(ty), slice::from_ref(&**item_segment));
897 let item_name = item_segment.ident;
899 .resolve_fully_qualified_call(span, item_name, ty, qself.span, hir_id)
901 let result = match error {
902 method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
903 _ => Err(ErrorGuaranteed),
906 // If we have a path like `MyTrait::missing_method`, then don't register
907 // a WF obligation for `dyn MyTrait` when method lookup fails. Otherwise,
908 // register a WF obligation so that we can detect any additional
909 // errors in the self type.
910 if !(matches!(error, method::MethodError::NoMatch(_)) && ty.is_trait()) {
911 self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None));
913 if item_name.name != kw::Empty {
914 if let Some(mut e) = self.report_method_error(
918 SelfSource::QPath(qself),
929 self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None));
932 // Write back the new resolution.
933 self.write_resolution(hir_id, result);
935 result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
937 slice::from_ref(&**item_segment),
941 /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise.
942 pub(in super::super) fn get_node_fn_decl(
945 ) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident, bool)> {
947 Node::Item(&hir::Item { ident, kind: hir::ItemKind::Fn(ref sig, ..), .. }) => {
948 // This is less than ideal, it will not suggest a return type span on any
949 // method called `main`, regardless of whether it is actually the entry point,
950 // but it will still present it as the reason for the expected type.
951 Some((&sig.decl, ident, ident.name != sym::main))
953 Node::TraitItem(&hir::TraitItem {
955 kind: hir::TraitItemKind::Fn(ref sig, ..),
957 }) => Some((&sig.decl, ident, true)),
958 Node::ImplItem(&hir::ImplItem {
960 kind: hir::ImplItemKind::Fn(ref sig, ..),
962 }) => Some((&sig.decl, ident, false)),
967 /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a
968 /// suggestion can be made, `None` otherwise.
969 pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, bool)> {
970 // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or
971 // `while` before reaching it, as block tail returns are not available in them.
972 self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| {
973 let parent = self.tcx.hir().get(blk_id);
974 self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main))
978 pub(in super::super) fn note_internal_mutation_in_method(
980 err: &mut Diagnostic,
981 expr: &hir::Expr<'_>,
985 if found != self.tcx.types.unit {
988 if let ExprKind::MethodCall(path_segment, [rcvr, ..], _) = expr.kind {
992 .expr_ty_adjusted_opt(rcvr)
993 .map_or(true, |ty| expected.peel_refs() != ty.peel_refs())
997 let mut sp = MultiSpan::from_span(path_segment.ident.span);
999 path_segment.ident.span,
1001 "this call modifies {} in-place",
1003 ExprKind::Path(QPath::Resolved(
1005 hir::Path { segments: [segment], .. },
1006 )) => format!("`{}`", segment.ident),
1007 _ => "its receiver".to_string(),
1013 "you probably want to use this value after calling the method...".to_string(),
1017 &format!("method `{}` modifies its receiver in-place", path_segment.ident),
1019 err.note(&format!("...instead of the `()` output of method `{}`", path_segment.ident));
1023 pub(in super::super) fn note_need_for_fn_pointer(
1025 err: &mut Diagnostic,
1029 let (sig, did, substs) = match (&expected.kind(), &found.kind()) {
1030 (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => {
1031 let sig1 = self.tcx.fn_sig(*did1).subst(self.tcx, substs1);
1032 let sig2 = self.tcx.fn_sig(*did2).subst(self.tcx, substs2);
1037 "different `fn` items always have unique types, even if their signatures are \
1040 (sig1, *did1, substs1)
1042 (ty::FnDef(did, substs), ty::FnPtr(sig2)) => {
1043 let sig1 = self.tcx.fn_sig(*did).subst(self.tcx, substs);
1047 (sig1, *did, substs)
1051 err.help(&format!("change the expected type to be function pointer `{}`", sig));
1053 "if the expected type is due to type inference, cast the expected `fn` to a function \
1054 pointer: `{} as {}`",
1055 self.tcx.def_path_str_with_substs(did, substs),
1060 pub(in super::super) fn could_remove_semicolon(
1062 blk: &'tcx hir::Block<'tcx>,
1063 expected_ty: Ty<'tcx>,
1064 ) -> Option<(Span, StatementAsExpression)> {
1065 // Be helpful when the user wrote `{... expr;}` and
1066 // taking the `;` off is enough to fix the error.
1067 let last_stmt = blk.stmts.last()?;
1068 let hir::StmtKind::Semi(ref last_expr) = last_stmt.kind else {
1071 let last_expr_ty = self.node_ty(last_expr.hir_id);
1072 let needs_box = match (last_expr_ty.kind(), expected_ty.kind()) {
1073 (ty::Opaque(last_def_id, _), ty::Opaque(exp_def_id, _))
1074 if last_def_id == exp_def_id =>
1076 StatementAsExpression::CorrectType
1078 (ty::Opaque(last_def_id, last_bounds), ty::Opaque(exp_def_id, exp_bounds)) => {
1080 "both opaque, likely future {:?} {:?} {:?} {:?}",
1081 last_def_id, last_bounds, exp_def_id, exp_bounds
1084 let last_local_id = last_def_id.as_local()?;
1085 let exp_local_id = exp_def_id.as_local()?;
1088 &self.tcx.hir().expect_item(last_local_id).kind,
1089 &self.tcx.hir().expect_item(exp_local_id).kind,
1092 hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: last_bounds, .. }),
1093 hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: exp_bounds, .. }),
1094 ) if iter::zip(*last_bounds, *exp_bounds).all(|(left, right)| {
1095 match (left, right) {
1097 hir::GenericBound::Trait(tl, ml),
1098 hir::GenericBound::Trait(tr, mr),
1099 ) if tl.trait_ref.trait_def_id() == tr.trait_ref.trait_def_id()
1105 hir::GenericBound::LangItemTrait(langl, _, _, argsl),
1106 hir::GenericBound::LangItemTrait(langr, _, _, argsr),
1107 ) if langl == langr => {
1108 // FIXME: consider the bounds!
1109 debug!("{:?} {:?}", argsl, argsr);
1116 StatementAsExpression::NeedsBoxing
1118 _ => StatementAsExpression::CorrectType,
1121 _ => StatementAsExpression::CorrectType,
1123 if (matches!(last_expr_ty.kind(), ty::Error(_))
1124 || self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err())
1125 && matches!(needs_box, StatementAsExpression::CorrectType)
1129 let span = if last_stmt.span.from_expansion() {
1130 let mac_call = original_sp(last_stmt.span, blk.span);
1131 self.tcx.sess.source_map().mac_call_stmt_semi_span(mac_call)?
1133 last_stmt.span.with_lo(last_stmt.span.hi() - BytePos(1))
1135 Some((span, needs_box))
1138 // Instantiates the given path, which must refer to an item with the given
1139 // number of type parameters and type.
1140 #[instrument(skip(self, span), level = "debug")]
1141 pub fn instantiate_value_path(
1143 segments: &[hir::PathSegment<'_>],
1144 self_ty: Option<Ty<'tcx>>,
1148 ) -> (Ty<'tcx>, Res) {
1151 let path_segs = match res {
1152 Res::Local(_) | Res::SelfCtor(_) => vec![],
1153 Res::Def(kind, def_id) => <dyn AstConv<'_>>::def_ids_for_value_path_segments(
1154 self, segments, self_ty, kind, def_id,
1156 _ => bug!("instantiate_value_path on {:?}", res),
1159 let mut user_self_ty = None;
1160 let mut is_alias_variant_ctor = false;
1162 Res::Def(DefKind::Ctor(CtorOf::Variant, _), _)
1163 if let Some(self_ty) = self_ty =>
1165 let adt_def = self_ty.ty_adt_def().unwrap();
1166 user_self_ty = Some(UserSelfTy { impl_def_id: adt_def.did, self_ty });
1167 is_alias_variant_ctor = true;
1169 Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => {
1170 let container = tcx.associated_item(def_id).container;
1171 debug!(?def_id, ?container);
1173 ty::TraitContainer(trait_did) => {
1174 callee::check_legal_trait_for_method_call(tcx, span, None, span, trait_did)
1176 ty::ImplContainer(impl_def_id) => {
1177 if segments.len() == 1 {
1178 // `<T>::assoc` will end up here, and so
1179 // can `T::assoc`. It this came from an
1180 // inherent impl, we need to record the
1181 // `T` for posterity (see `UserSelfTy` for
1183 let self_ty = self_ty.expect("UFCS sugared assoc missing Self");
1184 user_self_ty = Some(UserSelfTy { impl_def_id, self_ty });
1192 // Now that we have categorized what space the parameters for each
1193 // segment belong to, let's sort out the parameters that the user
1194 // provided (if any) into their appropriate spaces. We'll also report
1195 // errors if type parameters are provided in an inappropriate place.
1197 let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect();
1198 let generics_has_err = <dyn AstConv<'_>>::prohibit_generics(
1200 segments.iter().enumerate().filter_map(|(index, seg)| {
1201 if !generic_segs.contains(&index) || is_alias_variant_ctor {
1209 if let Res::Local(hid) = res {
1210 let ty = self.local_ty(span, hid).decl_ty;
1211 let ty = self.normalize_associated_types_in(span, ty);
1212 self.write_ty(hir_id, ty);
1216 if generics_has_err {
1217 // Don't try to infer type parameters when prohibited generic arguments were given.
1218 user_self_ty = None;
1221 // Now we have to compare the types that the user *actually*
1222 // provided against the types that were *expected*. If the user
1223 // did not provide any types, then we want to substitute inference
1224 // variables. If the user provided some types, we may still need
1225 // to add defaults. If the user provided *too many* types, that's
1228 let mut infer_args_for_err = FxHashSet::default();
1230 let mut explicit_late_bound = ExplicitLateBound::No;
1231 for &PathSeg(def_id, index) in &path_segs {
1232 let seg = &segments[index];
1233 let generics = tcx.generics_of(def_id);
1235 // Argument-position `impl Trait` is treated as a normal generic
1236 // parameter internally, but we don't allow users to specify the
1237 // parameter's value explicitly, so we have to do some error-
1239 let arg_count = <dyn AstConv<'_>>::check_generic_arg_count_for_call(
1248 if let ExplicitLateBound::Yes = arg_count.explicit_late_bound {
1249 explicit_late_bound = ExplicitLateBound::Yes;
1252 if let Err(GenericArgCountMismatch { reported: Some(_), .. }) = arg_count.correct {
1253 infer_args_for_err.insert(index);
1254 self.set_tainted_by_errors(); // See issue #53251.
1258 let has_self = path_segs
1260 .map(|PathSeg(def_id, _)| tcx.generics_of(*def_id).has_self)
1263 let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res {
1264 let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id));
1266 ty::Adt(adt_def, substs) if adt_def.has_ctor() => {
1267 let variant = adt_def.non_enum_variant();
1268 let ctor_def_id = variant.ctor_def_id.unwrap();
1270 Res::Def(DefKind::Ctor(CtorOf::Struct, variant.ctor_kind), ctor_def_id),
1275 let mut err = tcx.sess.struct_span_err(
1277 "the `Self` constructor can only be used with tuple or unit structs",
1279 if let Some(adt_def) = ty.ty_adt_def() {
1280 match adt_def.adt_kind() {
1282 err.help("did you mean to use one of the enum's variants?");
1284 AdtKind::Struct | AdtKind::Union => {
1285 err.span_suggestion(
1287 "use curly brackets",
1288 String::from("Self { /* fields */ }"),
1289 Applicability::HasPlaceholders,
1296 return (tcx.ty_error(), res);
1302 let def_id = res.def_id();
1304 // The things we are substituting into the type should not contain
1305 // escaping late-bound regions, and nor should the base type scheme.
1306 let ty = tcx.type_of(def_id);
1308 let arg_count = GenericArgCountResult {
1309 explicit_late_bound,
1310 correct: if infer_args_for_err.is_empty() {
1313 Err(GenericArgCountMismatch::default())
1317 struct CreateCtorSubstsContext<'a, 'tcx> {
1318 fcx: &'a FnCtxt<'a, 'tcx>,
1320 path_segs: &'a [PathSeg],
1321 infer_args_for_err: &'a FxHashSet<usize>,
1322 segments: &'a [hir::PathSegment<'a>],
1324 impl<'tcx, 'a> CreateSubstsForGenericArgsCtxt<'a, 'tcx> for CreateCtorSubstsContext<'a, 'tcx> {
1328 ) -> (Option<&'a hir::GenericArgs<'a>>, bool) {
1329 if let Some(&PathSeg(_, index)) =
1330 self.path_segs.iter().find(|&PathSeg(did, _)| *did == def_id)
1332 // If we've encountered an `impl Trait`-related error, we're just
1333 // going to infer the arguments for better error messages.
1334 if !self.infer_args_for_err.contains(&index) {
1335 // Check whether the user has provided generic arguments.
1336 if let Some(ref data) = self.segments[index].args {
1337 return (Some(data), self.segments[index].infer_args);
1340 return (None, self.segments[index].infer_args);
1348 param: &ty::GenericParamDef,
1349 arg: &GenericArg<'_>,
1350 ) -> subst::GenericArg<'tcx> {
1351 match (¶m.kind, arg) {
1352 (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
1353 <dyn AstConv<'_>>::ast_region_to_region(self.fcx, lt, Some(param)).into()
1355 (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
1356 self.fcx.to_ty(ty).into()
1358 (GenericParamDefKind::Const { .. }, GenericArg::Const(ct)) => {
1359 self.fcx.const_arg_to_const(&ct.value, param.def_id).into()
1361 (GenericParamDefKind::Type { .. }, GenericArg::Infer(inf)) => {
1362 self.fcx.ty_infer(Some(param), inf.span).into()
1364 (GenericParamDefKind::Const { .. }, GenericArg::Infer(inf)) => {
1365 let tcx = self.fcx.tcx();
1366 self.fcx.ct_infer(tcx.type_of(param.def_id), Some(param), inf.span).into()
1368 _ => unreachable!(),
1374 substs: Option<&[subst::GenericArg<'tcx>]>,
1375 param: &ty::GenericParamDef,
1377 ) -> subst::GenericArg<'tcx> {
1378 let tcx = self.fcx.tcx();
1380 GenericParamDefKind::Lifetime => {
1381 self.fcx.re_infer(Some(param), self.span).unwrap().into()
1383 GenericParamDefKind::Type { has_default, .. } => {
1384 if !infer_args && has_default {
1385 // If we have a default, then we it doesn't matter that we're not
1386 // inferring the type arguments: we provide the default where any
1388 let default = tcx.type_of(param.def_id);
1392 default.subst_spanned(tcx, substs.unwrap(), Some(self.span)),
1396 // If no type arguments were provided, we have to infer them.
1397 // This case also occurs as a result of some malformed input, e.g.
1398 // a lifetime argument being given instead of a type parameter.
1399 // Using inference instead of `Error` gives better error messages.
1400 self.fcx.var_for_def(self.span, param)
1403 GenericParamDefKind::Const { has_default, .. } => {
1404 if !infer_args && has_default {
1405 tcx.const_param_default(param.def_id)
1406 .subst_spanned(tcx, substs.unwrap(), Some(self.span))
1409 self.fcx.var_for_def(self.span, param)
1416 let substs = self_ctor_substs.unwrap_or_else(|| {
1417 <dyn AstConv<'_>>::create_substs_for_generic_args(
1424 &mut CreateCtorSubstsContext {
1427 path_segs: &path_segs,
1428 infer_args_for_err: &infer_args_for_err,
1433 assert!(!substs.has_escaping_bound_vars());
1434 assert!(!ty.has_escaping_bound_vars());
1436 // First, store the "user substs" for later.
1437 self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty);
1439 self.add_required_obligations(span, def_id, &substs);
1441 // Substitute the values for the type parameters into the type of
1442 // the referenced item.
1443 let ty_substituted = self.instantiate_type_scheme(span, &substs, ty);
1445 if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
1446 // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
1447 // is inherent, there is no `Self` parameter; instead, the impl needs
1448 // type parameters, which we can infer by unifying the provided `Self`
1449 // with the substituted impl type.
1450 // This also occurs for an enum variant on a type alias.
1451 let ty = tcx.type_of(impl_def_id);
1453 let impl_ty = self.instantiate_type_scheme(span, &substs, ty);
1454 match self.at(&self.misc(span), self.param_env).eq(impl_ty, self_ty) {
1455 Ok(ok) => self.register_infer_ok_obligations(ok),
1457 self.tcx.sess.delay_span_bug(
1460 "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?",
1469 debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted);
1470 self.write_substs(hir_id, substs);
1472 (ty_substituted, res)
1475 /// Add all the obligations that are required, substituting and normalized appropriately.
1476 crate fn add_required_obligations(&self, span: Span, def_id: DefId, substs: &SubstsRef<'tcx>) {
1477 self.add_required_obligations_with_code(
1481 traits::ItemObligation(def_id),
1485 #[tracing::instrument(level = "debug", skip(self, span, def_id, substs))]
1486 fn add_required_obligations_with_code(
1490 substs: &SubstsRef<'tcx>,
1491 code: ObligationCauseCode<'tcx>,
1493 let (bounds, _) = self.instantiate_bounds(span, def_id, &substs);
1495 for obligation in traits::predicates_for_generics(
1496 traits::ObligationCause::new(span, self.body_id, code),
1500 self.register_predicate(obligation);
1504 /// Resolves `typ` by a single level if `typ` is a type variable.
1505 /// If no resolution is possible, then an error is reported.
1506 /// Numeric inference variables may be left unresolved.
1507 pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
1508 let ty = self.resolve_vars_with_obligations(ty);
1509 if !ty.is_ty_var() {
1512 if !self.is_tainted_by_errors() {
1513 self.emit_inference_failure_err((**self).body_id, sp, ty.into(), vec![], E0282)
1514 .note("type must be known at this point")
1517 let err = self.tcx.ty_error();
1518 self.demand_suptype(sp, err, ty);
1523 pub(in super::super) fn with_breakable_ctxt<F: FnOnce() -> R, R>(
1526 ctxt: BreakableCtxt<'tcx>,
1528 ) -> (BreakableCtxt<'tcx>, R) {
1531 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
1532 index = enclosing_breakables.stack.len();
1533 enclosing_breakables.by_id.insert(id, index);
1534 enclosing_breakables.stack.push(ctxt);
1538 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
1539 debug_assert!(enclosing_breakables.stack.len() == index + 1);
1540 enclosing_breakables.by_id.remove(&id).expect("missing breakable context");
1541 enclosing_breakables.stack.pop().expect("missing breakable context")
1546 /// Instantiate a QueryResponse in a probe context, without a
1547 /// good ObligationCause.
1548 pub(in super::super) fn probe_instantiate_query_response(
1551 original_values: &OriginalQueryValues<'tcx>,
1552 query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
1553 ) -> InferResult<'tcx, Ty<'tcx>> {
1554 self.instantiate_query_response_and_region_obligations(
1555 &traits::ObligationCause::misc(span, self.body_id),
1562 /// Returns `true` if an expression is contained inside the LHS of an assignment expression.
1563 pub(in super::super) fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool {
1564 let mut contained_in_place = false;
1566 while let hir::Node::Expr(parent_expr) =
1567 self.tcx.hir().get(self.tcx.hir().get_parent_node(expr_id))
1569 match &parent_expr.kind {
1570 hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => {
1571 if lhs.hir_id == expr_id {
1572 contained_in_place = true;
1578 expr_id = parent_expr.hir_id;