1 pub use self::freshen::TypeFreshener;
2 pub use self::lexical_region_resolve::RegionResolutionError;
3 pub use self::LateBoundRegionConversionTime::*;
4 pub use self::RegionVariableOrigin::*;
5 pub use self::SubregionOrigin::*;
6 pub use self::ValuePairs::*;
8 use self::opaque_types::OpaqueTypeStorage;
9 pub(crate) use self::undo_log::{InferCtxtUndoLogs, Snapshot, UndoLog};
11 use crate::traits::{self, ObligationCause, PredicateObligations, TraitEngine, TraitEngineExt};
13 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
14 use rustc_data_structures::sync::Lrc;
15 use rustc_data_structures::undo_log::Rollback;
16 use rustc_data_structures::unify as ut;
17 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed};
18 use rustc_hir::def_id::{DefId, LocalDefId};
19 use rustc_hir::hir_id::OwnerId;
20 use rustc_middle::infer::canonical::{Canonical, CanonicalVarValues};
21 use rustc_middle::infer::unify_key::{ConstVarValue, ConstVariableValue};
22 use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind, ToType};
23 use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult};
24 use rustc_middle::mir::ConstraintCategory;
25 use rustc_middle::traits::select;
26 use rustc_middle::ty::abstract_const::{AbstractConst, FailureKind};
27 use rustc_middle::ty::error::{ExpectedFound, TypeError};
28 use rustc_middle::ty::fold::BoundVarReplacerDelegate;
29 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
30 use rustc_middle::ty::relate::RelateResult;
31 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, SubstsRef};
32 use rustc_middle::ty::visit::TypeVisitable;
33 pub use rustc_middle::ty::IntVarValue;
34 use rustc_middle::ty::{self, GenericParamDefKind, InferConst, Ty, TyCtxt};
35 use rustc_middle::ty::{ConstVid, FloatVid, IntVid, TyVid};
36 use rustc_span::symbol::Symbol;
37 use rustc_span::{Span, DUMMY_SP};
39 use std::cell::{Cell, Ref, RefCell};
42 use self::combine::CombineFields;
43 use self::free_regions::RegionRelations;
44 use self::lexical_region_resolve::LexicalRegionResolutions;
45 use self::outlives::env::OutlivesEnvironment;
46 use self::region_constraints::{GenericKind, RegionConstraintData, VarInfos, VerifyBound};
47 use self::region_constraints::{
48 RegionConstraintCollector, RegionConstraintStorage, RegionSnapshot,
50 use self::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
56 pub mod error_reporting;
63 mod lexical_region_resolve;
69 pub mod region_constraints;
72 pub mod type_variable;
77 pub struct InferOk<'tcx, T> {
79 pub obligations: PredicateObligations<'tcx>,
81 pub type InferResult<'tcx, T> = Result<InferOk<'tcx, T>, TypeError<'tcx>>;
83 pub type Bound<T> = Option<T>;
84 pub type UnitResult<'tcx> = RelateResult<'tcx, ()>; // "unify result"
85 pub type FixupResult<'tcx, T> = Result<T, FixupError<'tcx>>; // "fixup result"
87 pub(crate) type UnificationTable<'a, 'tcx, T> = ut::UnificationTable<
88 ut::InPlace<T, &'a mut ut::UnificationStorage<T>, &'a mut InferCtxtUndoLogs<'tcx>>,
91 /// This type contains all the things within `InferCtxt` that sit within a
92 /// `RefCell` and are involved with taking/rolling back snapshots. Snapshot
93 /// operations are hot enough that we want only one call to `borrow_mut` per
94 /// call to `start_snapshot` and `rollback_to`.
96 pub struct InferCtxtInner<'tcx> {
97 /// Cache for projections. This cache is snapshotted along with the infcx.
99 /// Public so that `traits::project` can use it.
100 pub projection_cache: traits::ProjectionCacheStorage<'tcx>,
102 /// We instantiate `UnificationTable` with `bounds<Ty>` because the types
103 /// that might instantiate a general type variable have an order,
104 /// represented by its upper and lower bounds.
105 type_variable_storage: type_variable::TypeVariableStorage<'tcx>,
107 /// Map from const parameter variable to the kind of const it represents.
108 const_unification_storage: ut::UnificationTableStorage<ty::ConstVid<'tcx>>,
110 /// Map from integral variable to the kind of integer it represents.
111 int_unification_storage: ut::UnificationTableStorage<ty::IntVid>,
113 /// Map from floating variable to the kind of float it represents.
114 float_unification_storage: ut::UnificationTableStorage<ty::FloatVid>,
116 /// Tracks the set of region variables and the constraints between them.
117 /// This is initially `Some(_)` but when
118 /// `resolve_regions_and_report_errors` is invoked, this gets set to `None`
119 /// -- further attempts to perform unification, etc., may fail if new
120 /// region constraints would've been added.
121 region_constraint_storage: Option<RegionConstraintStorage<'tcx>>,
123 /// A set of constraints that regionck must validate. Each
124 /// constraint has the form `T:'a`, meaning "some type `T` must
125 /// outlive the lifetime 'a". These constraints derive from
126 /// instantiated type parameters. So if you had a struct defined
128 /// ```ignore (illustrative)
129 /// struct Foo<T:'static> { ... }
131 /// then in some expression `let x = Foo { ... }` it will
132 /// instantiate the type parameter `T` with a fresh type `$0`. At
133 /// the same time, it will record a region obligation of
134 /// `$0:'static`. This will get checked later by regionck. (We
135 /// can't generally check these things right away because we have
136 /// to wait until types are resolved.)
138 /// These are stored in a map keyed to the id of the innermost
139 /// enclosing fn body / static initializer expression. This is
140 /// because the location where the obligation was incurred can be
141 /// relevant with respect to which sublifetime assumptions are in
142 /// place. The reason that we store under the fn-id, and not
143 /// something more fine-grained, is so that it is easier for
144 /// regionck to be sure that it has found *all* the region
145 /// obligations (otherwise, it's easy to fail to walk to a
146 /// particular node-id).
148 /// Before running `resolve_regions_and_report_errors`, the creator
149 /// of the inference context is expected to invoke
150 /// [`InferCtxt::process_registered_region_obligations`]
151 /// for each body-id in this map, which will process the
152 /// obligations within. This is expected to be done 'late enough'
153 /// that all type inference variables have been bound and so forth.
154 region_obligations: Vec<RegionObligation<'tcx>>,
156 undo_log: InferCtxtUndoLogs<'tcx>,
158 /// Caches for opaque type inference.
159 pub opaque_type_storage: OpaqueTypeStorage<'tcx>,
162 impl<'tcx> InferCtxtInner<'tcx> {
163 fn new() -> InferCtxtInner<'tcx> {
165 projection_cache: Default::default(),
166 type_variable_storage: type_variable::TypeVariableStorage::new(),
167 undo_log: InferCtxtUndoLogs::default(),
168 const_unification_storage: ut::UnificationTableStorage::new(),
169 int_unification_storage: ut::UnificationTableStorage::new(),
170 float_unification_storage: ut::UnificationTableStorage::new(),
171 region_constraint_storage: Some(RegionConstraintStorage::new()),
172 region_obligations: vec![],
173 opaque_type_storage: Default::default(),
178 pub fn region_obligations(&self) -> &[RegionObligation<'tcx>] {
179 &self.region_obligations
183 pub fn projection_cache(&mut self) -> traits::ProjectionCache<'_, 'tcx> {
184 self.projection_cache.with_log(&mut self.undo_log)
188 fn type_variables(&mut self) -> type_variable::TypeVariableTable<'_, 'tcx> {
189 self.type_variable_storage.with_log(&mut self.undo_log)
193 pub fn opaque_types(&mut self) -> opaque_types::OpaqueTypeTable<'_, 'tcx> {
194 self.opaque_type_storage.with_log(&mut self.undo_log)
198 fn int_unification_table(
200 ) -> ut::UnificationTable<
203 &mut ut::UnificationStorage<ty::IntVid>,
204 &mut InferCtxtUndoLogs<'tcx>,
207 self.int_unification_storage.with_log(&mut self.undo_log)
211 fn float_unification_table(
213 ) -> ut::UnificationTable<
216 &mut ut::UnificationStorage<ty::FloatVid>,
217 &mut InferCtxtUndoLogs<'tcx>,
220 self.float_unification_storage.with_log(&mut self.undo_log)
224 fn const_unification_table(
226 ) -> ut::UnificationTable<
229 &mut ut::UnificationStorage<ty::ConstVid<'tcx>>,
230 &mut InferCtxtUndoLogs<'tcx>,
233 self.const_unification_storage.with_log(&mut self.undo_log)
237 pub fn unwrap_region_constraints(&mut self) -> RegionConstraintCollector<'_, 'tcx> {
238 self.region_constraint_storage
240 .expect("region constraints already solved")
241 .with_log(&mut self.undo_log)
245 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
246 pub enum DefiningAnchor {
247 /// `DefId` of the item.
249 /// When opaque types are not resolved, we `Bubble` up, meaning
250 /// return the opaque/hidden type pair from query, for caller of query to handle it.
252 /// Used to catch type mismatch errors when handling opaque types.
256 pub struct InferCtxt<'a, 'tcx> {
257 pub tcx: TyCtxt<'tcx>,
259 /// The `DefId` of the item in whose context we are performing inference or typeck.
260 /// It is used to check whether an opaque type use is a defining use.
262 /// If it is `DefiningAnchor::Bubble`, we can't resolve opaque types here and need to bubble up
263 /// the obligation. This frequently happens for
264 /// short lived InferCtxt within queries. The opaque type obligations are forwarded
265 /// to the outside until the end up in an `InferCtxt` for typeck or borrowck.
267 /// It is default value is `DefiningAnchor::Error`, this way it is easier to catch errors that
268 /// might come up during inference or typeck.
269 pub defining_use_anchor: DefiningAnchor,
271 /// Whether this inference context should care about region obligations in
272 /// the root universe. Most notably, this is used during hir typeck as region
273 /// solving is left to borrowck instead.
274 pub considering_regions: bool,
276 /// During type-checking/inference of a body, `in_progress_typeck_results`
277 /// contains a reference to the typeck results being built up, which are
278 /// used for reading closure kinds/signatures as they are inferred,
279 /// and for error reporting logic to read arbitrary node types.
280 pub in_progress_typeck_results: Option<&'a RefCell<ty::TypeckResults<'tcx>>>,
282 pub inner: RefCell<InferCtxtInner<'tcx>>,
284 /// If set, this flag causes us to skip the 'leak check' during
285 /// higher-ranked subtyping operations. This flag is a temporary one used
286 /// to manage the removal of the leak-check: for the time being, we still run the
287 /// leak-check, but we issue warnings. This flag can only be set to true
288 /// when entering a snapshot.
289 skip_leak_check: Cell<bool>,
291 /// Once region inference is done, the values for each variable.
292 lexical_region_resolutions: RefCell<Option<LexicalRegionResolutions<'tcx>>>,
294 /// Caches the results of trait selection. This cache is used
295 /// for things that have to do with the parameters in scope.
296 pub selection_cache: select::SelectionCache<'tcx>,
298 /// Caches the results of trait evaluation.
299 pub evaluation_cache: select::EvaluationCache<'tcx>,
301 /// the set of predicates on which errors have been reported, to
302 /// avoid reporting the same error twice.
303 pub reported_trait_errors: RefCell<FxHashMap<Span, Vec<ty::Predicate<'tcx>>>>,
305 pub reported_closure_mismatch: RefCell<FxHashSet<(Span, Option<Span>)>>,
307 /// When an error occurs, we want to avoid reporting "derived"
308 /// errors that are due to this original failure. Normally, we
309 /// handle this with the `err_count_on_creation` count, which
310 /// basically just tracks how many errors were reported when we
311 /// started type-checking a fn and checks to see if any new errors
312 /// have been reported since then. Not great, but it works.
314 /// However, when errors originated in other passes -- notably
315 /// resolve -- this heuristic breaks down. Therefore, we have this
316 /// auxiliary flag that one can set whenever one creates a
317 /// type-error that is due to an error in a prior pass.
319 /// Don't read this flag directly, call `is_tainted_by_errors()`
320 /// and `set_tainted_by_errors()`.
321 tainted_by_errors: Cell<Option<ErrorGuaranteed>>,
323 /// Track how many errors were reported when this infcx is created.
324 /// If the number of errors increases, that's also a sign (line
325 /// `tainted_by_errors`) to avoid reporting certain kinds of errors.
326 // FIXME(matthewjasper) Merge into `tainted_by_errors`
327 err_count_on_creation: usize,
329 /// This flag is true while there is an active snapshot.
330 in_snapshot: Cell<bool>,
332 /// What is the innermost universe we have created? Starts out as
333 /// `UniverseIndex::root()` but grows from there as we enter
334 /// universal quantifiers.
336 /// N.B., at present, we exclude the universal quantifiers on the
337 /// item we are type-checking, and just consider those names as
338 /// part of the root universe. So this would only get incremented
339 /// when we enter into a higher-ranked (`for<..>`) type or trait
341 universe: Cell<ty::UniverseIndex>,
343 normalize_fn_sig_for_diagnostic:
344 Option<Lrc<dyn Fn(&InferCtxt<'_, 'tcx>, ty::PolyFnSig<'tcx>) -> ty::PolyFnSig<'tcx>>>,
347 /// See the `error_reporting` module for more details.
348 #[derive(Clone, Copy, Debug, PartialEq, Eq, TypeFoldable, TypeVisitable)]
349 pub enum ValuePairs<'tcx> {
350 Regions(ExpectedFound<ty::Region<'tcx>>),
351 Terms(ExpectedFound<ty::Term<'tcx>>),
352 TraitRefs(ExpectedFound<ty::TraitRef<'tcx>>),
353 PolyTraitRefs(ExpectedFound<ty::PolyTraitRef<'tcx>>),
356 impl<'tcx> ValuePairs<'tcx> {
357 pub fn ty(&self) -> Option<(Ty<'tcx>, Ty<'tcx>)> {
358 if let ValuePairs::Terms(ExpectedFound { expected, found }) = self
359 && let Some(expected) = expected.ty()
360 && let Some(found) = found.ty()
362 Some((expected, found))
369 /// The trace designates the path through inference that we took to
370 /// encounter an error or subtyping constraint.
372 /// See the `error_reporting` module for more details.
373 #[derive(Clone, Debug)]
374 pub struct TypeTrace<'tcx> {
375 pub cause: ObligationCause<'tcx>,
376 pub values: ValuePairs<'tcx>,
379 /// The origin of a `r1 <= r2` constraint.
381 /// See `error_reporting` module for more details
382 #[derive(Clone, Debug)]
383 pub enum SubregionOrigin<'tcx> {
384 /// Arose from a subtyping relation
385 Subtype(Box<TypeTrace<'tcx>>),
387 /// When casting `&'a T` to an `&'b Trait` object,
388 /// relating `'a` to `'b`
389 RelateObjectBound(Span),
391 /// Some type parameter was instantiated with the given type,
392 /// and that type must outlive some region.
393 RelateParamBound(Span, Ty<'tcx>, Option<Span>),
395 /// The given region parameter was instantiated with a region
396 /// that must outlive some other region.
397 RelateRegionParamBound(Span),
399 /// Creating a pointer `b` to contents of another reference
402 /// Creating a pointer `b` to contents of an upvar
403 ReborrowUpvar(Span, ty::UpvarId),
405 /// Data with type `Ty<'tcx>` was borrowed
406 DataBorrowed(Ty<'tcx>, Span),
408 /// (&'a &'b T) where a >= b
409 ReferenceOutlivesReferent(Ty<'tcx>, Span),
411 /// Comparing the signature and requirements of an impl method against
412 /// the containing trait.
413 CompareImplItemObligation {
415 impl_item_def_id: LocalDefId,
416 trait_item_def_id: DefId,
419 /// Checking that the bounds of a trait's associated type hold for a given impl
420 CheckAssociatedTypeBounds {
421 parent: Box<SubregionOrigin<'tcx>>,
422 impl_item_def_id: LocalDefId,
423 trait_item_def_id: DefId,
426 AscribeUserTypeProvePredicate(Span),
429 // `SubregionOrigin` is used a lot. Make sure it doesn't unintentionally get bigger.
430 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
431 static_assert_size!(SubregionOrigin<'_>, 32);
433 impl<'tcx> SubregionOrigin<'tcx> {
434 pub fn to_constraint_category(&self) -> ConstraintCategory<'tcx> {
436 Self::Subtype(type_trace) => type_trace.cause.to_constraint_category(),
437 Self::AscribeUserTypeProvePredicate(span) => ConstraintCategory::Predicate(*span),
438 _ => ConstraintCategory::BoringNoLocation,
443 /// Times when we replace late-bound regions with variables:
444 #[derive(Clone, Copy, Debug)]
445 pub enum LateBoundRegionConversionTime {
446 /// when a fn is called
449 /// when two higher-ranked types are compared
452 /// when projecting an associated type
453 AssocTypeProjection(DefId),
456 /// Reasons to create a region inference variable
458 /// See `error_reporting` module for more details
459 #[derive(Copy, Clone, Debug)]
460 pub enum RegionVariableOrigin {
461 /// Region variables created for ill-categorized reasons,
462 /// mostly indicates places in need of refactoring
465 /// Regions created by a `&P` or `[...]` pattern
468 /// Regions created by `&` operator
471 /// Regions created as part of an autoref of a method receiver
474 /// Regions created as part of an automatic coercion
477 /// Region variables created as the values for early-bound regions
478 EarlyBoundRegion(Span, Symbol),
480 /// Region variables created for bound regions
481 /// in a function or method that is called
482 LateBoundRegion(Span, ty::BoundRegionKind, LateBoundRegionConversionTime),
484 UpvarRegion(ty::UpvarId, Span),
486 /// This origin is used for the inference variables that we create
487 /// during NLL region processing.
488 Nll(NllRegionVariableOrigin),
491 #[derive(Copy, Clone, Debug)]
492 pub enum NllRegionVariableOrigin {
493 /// During NLL region processing, we create variables for free
494 /// regions that we encounter in the function signature and
495 /// elsewhere. This origin indices we've got one of those.
498 /// "Universal" instantiation of a higher-ranked region (e.g.,
499 /// from a `for<'a> T` binder). Meant to represent "any region".
500 Placeholder(ty::PlaceholderRegion),
503 /// If this is true, then this variable was created to represent a lifetime
504 /// bound in a `for` binder. For example, it might have been created to
505 /// represent the lifetime `'a` in a type like `for<'a> fn(&'a u32)`.
506 /// Such variables are created when we are trying to figure out if there
507 /// is any valid instantiation of `'a` that could fit into some scenario.
509 /// This is used to inform error reporting: in the case that we are trying to
510 /// determine whether there is any valid instantiation of a `'a` variable that meets
511 /// some constraint C, we want to blame the "source" of that `for` type,
512 /// rather than blaming the source of the constraint C.
517 // FIXME(eddyb) investigate overlap between this and `TyOrConstInferVar`.
518 #[derive(Copy, Clone, Debug)]
519 pub enum FixupError<'tcx> {
520 UnresolvedIntTy(IntVid),
521 UnresolvedFloatTy(FloatVid),
523 UnresolvedConst(ConstVid<'tcx>),
526 /// See the `region_obligations` field for more information.
527 #[derive(Clone, Debug)]
528 pub struct RegionObligation<'tcx> {
529 pub sub_region: ty::Region<'tcx>,
530 pub sup_type: Ty<'tcx>,
531 pub origin: SubregionOrigin<'tcx>,
534 impl<'tcx> fmt::Display for FixupError<'tcx> {
535 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
536 use self::FixupError::*;
539 UnresolvedIntTy(_) => write!(
541 "cannot determine the type of this integer; \
542 add a suffix to specify the type explicitly"
544 UnresolvedFloatTy(_) => write!(
546 "cannot determine the type of this number; \
547 add a suffix to specify the type explicitly"
549 UnresolvedTy(_) => write!(f, "unconstrained type"),
550 UnresolvedConst(_) => write!(f, "unconstrained const value"),
555 /// A temporary returned by `tcx.infer_ctxt()`. This is necessary
556 /// for multiple `InferCtxt` to share the same `in_progress_typeck_results`
557 /// without using `Rc` or something similar.
558 pub struct InferCtxtBuilder<'tcx> {
560 defining_use_anchor: DefiningAnchor,
561 considering_regions: bool,
562 fresh_typeck_results: Option<RefCell<ty::TypeckResults<'tcx>>>,
563 normalize_fn_sig_for_diagnostic:
564 Option<Lrc<dyn Fn(&InferCtxt<'_, 'tcx>, ty::PolyFnSig<'tcx>) -> ty::PolyFnSig<'tcx>>>,
567 pub trait TyCtxtInferExt<'tcx> {
568 fn infer_ctxt(self) -> InferCtxtBuilder<'tcx>;
571 impl<'tcx> TyCtxtInferExt<'tcx> for TyCtxt<'tcx> {
572 fn infer_ctxt(self) -> InferCtxtBuilder<'tcx> {
575 defining_use_anchor: DefiningAnchor::Error,
576 considering_regions: true,
577 fresh_typeck_results: None,
578 normalize_fn_sig_for_diagnostic: None,
583 impl<'tcx> InferCtxtBuilder<'tcx> {
584 /// Used only by `rustc_hir_analysis` during body type-checking/inference,
585 /// will initialize `in_progress_typeck_results` with fresh `TypeckResults`.
586 /// Will also change the scope for opaque type defining use checks to the given owner.
587 pub fn with_fresh_in_progress_typeck_results(mut self, table_owner: OwnerId) -> Self {
588 self.fresh_typeck_results = Some(RefCell::new(ty::TypeckResults::new(table_owner)));
589 self.with_opaque_type_inference(DefiningAnchor::Bind(table_owner.def_id))
592 /// Whenever the `InferCtxt` should be able to handle defining uses of opaque types,
593 /// you need to call this function. Otherwise the opaque type will be treated opaquely.
595 /// It is only meant to be called in two places, for typeck
596 /// (via `with_fresh_in_progress_typeck_results`) and for the inference context used
598 pub fn with_opaque_type_inference(mut self, defining_use_anchor: DefiningAnchor) -> Self {
599 self.defining_use_anchor = defining_use_anchor;
603 pub fn ignoring_regions(mut self) -> Self {
604 self.considering_regions = false;
608 pub fn with_normalize_fn_sig_for_diagnostic(
610 fun: Lrc<dyn Fn(&InferCtxt<'_, 'tcx>, ty::PolyFnSig<'tcx>) -> ty::PolyFnSig<'tcx>>,
612 self.normalize_fn_sig_for_diagnostic = Some(fun);
616 /// Given a canonical value `C` as a starting point, create an
617 /// inference context that contains each of the bound values
618 /// within instantiated as a fresh variable. The `f` closure is
619 /// invoked with the new infcx, along with the instantiated value
620 /// `V` and a substitution `S`. This substitution `S` maps from
621 /// the bound values in `C` to their instantiated values in `V`
622 /// (in other words, `S(C) = V`).
623 pub fn enter_with_canonical<T, R>(
626 canonical: &Canonical<'tcx, T>,
627 f: impl for<'a> FnOnce(InferCtxt<'a, 'tcx>, T, CanonicalVarValues<'tcx>) -> R,
630 T: TypeFoldable<'tcx>,
634 infcx.instantiate_canonical_with_fresh_inference_vars(span, canonical);
635 f(infcx, value, subst)
639 pub fn enter<R>(&mut self, f: impl for<'a> FnOnce(InferCtxt<'a, 'tcx>) -> R) -> R {
640 let InferCtxtBuilder {
644 ref fresh_typeck_results,
645 ref normalize_fn_sig_for_diagnostic,
647 let in_progress_typeck_results = fresh_typeck_results.as_ref();
652 in_progress_typeck_results,
653 inner: RefCell::new(InferCtxtInner::new()),
654 lexical_region_resolutions: RefCell::new(None),
655 selection_cache: Default::default(),
656 evaluation_cache: Default::default(),
657 reported_trait_errors: Default::default(),
658 reported_closure_mismatch: Default::default(),
659 tainted_by_errors: Cell::new(None),
660 err_count_on_creation: tcx.sess.err_count(),
661 in_snapshot: Cell::new(false),
662 skip_leak_check: Cell::new(false),
663 universe: Cell::new(ty::UniverseIndex::ROOT),
664 normalize_fn_sig_for_diagnostic: normalize_fn_sig_for_diagnostic
671 impl<'tcx, T> InferOk<'tcx, T> {
672 pub fn unit(self) -> InferOk<'tcx, ()> {
673 InferOk { value: (), obligations: self.obligations }
676 /// Extracts `value`, registering any obligations into `fulfill_cx`.
677 pub fn into_value_registering_obligations(
679 infcx: &InferCtxt<'_, 'tcx>,
680 fulfill_cx: &mut dyn TraitEngine<'tcx>,
682 let InferOk { value, obligations } = self;
683 fulfill_cx.register_predicate_obligations(infcx, obligations);
688 impl<'tcx> InferOk<'tcx, ()> {
689 pub fn into_obligations(self) -> PredicateObligations<'tcx> {
694 #[must_use = "once you start a snapshot, you should always consume it"]
695 pub struct CombinedSnapshot<'a, 'tcx> {
696 undo_snapshot: Snapshot<'tcx>,
697 region_constraints_snapshot: RegionSnapshot,
698 universe: ty::UniverseIndex,
699 was_in_snapshot: bool,
700 _in_progress_typeck_results: Option<Ref<'a, ty::TypeckResults<'tcx>>>,
703 impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
704 /// calls `tcx.try_unify_abstract_consts` after
705 /// canonicalizing the consts.
706 #[instrument(skip(self), level = "debug")]
707 pub fn try_unify_abstract_consts(
709 a: ty::UnevaluatedConst<'tcx>,
710 b: ty::UnevaluatedConst<'tcx>,
711 param_env: ty::ParamEnv<'tcx>,
713 // Reject any attempt to unify two unevaluated constants that contain inference
714 // variables, since inference variables in queries lead to ICEs.
715 if a.substs.has_non_region_infer()
716 || b.substs.has_non_region_infer()
717 || param_env.has_non_region_infer()
719 debug!("a or b or param_env contain infer vars in its substs -> cannot unify");
723 let param_env_and = param_env.and((a, b));
724 let erased = self.tcx.erase_regions(param_env_and);
725 debug!("after erase_regions: {:?}", erased);
727 self.tcx.try_unify_abstract_consts(erased)
730 pub fn is_in_snapshot(&self) -> bool {
731 self.in_snapshot.get()
734 pub fn freshen<T: TypeFoldable<'tcx>>(&self, t: T) -> T {
735 t.fold_with(&mut self.freshener())
738 /// Returns the origin of the type variable identified by `vid`, or `None`
739 /// if this is not a type variable.
741 /// No attempt is made to resolve `ty`.
742 pub fn type_var_origin(&'a self, ty: Ty<'tcx>) -> Option<TypeVariableOrigin> {
744 ty::Infer(ty::TyVar(vid)) => {
745 Some(*self.inner.borrow_mut().type_variables().var_origin(vid))
751 pub fn freshener<'b>(&'b self) -> TypeFreshener<'b, 'tcx> {
752 freshen::TypeFreshener::new(self, false)
755 /// Like `freshener`, but does not replace `'static` regions.
756 pub fn freshener_keep_static<'b>(&'b self) -> TypeFreshener<'b, 'tcx> {
757 freshen::TypeFreshener::new(self, true)
760 pub fn unsolved_variables(&self) -> Vec<Ty<'tcx>> {
761 let mut inner = self.inner.borrow_mut();
762 let mut vars: Vec<Ty<'_>> = inner
764 .unsolved_variables()
766 .map(|t| self.tcx.mk_ty_var(t))
769 (0..inner.int_unification_table().len())
770 .map(|i| ty::IntVid { index: i as u32 })
771 .filter(|&vid| inner.int_unification_table().probe_value(vid).is_none())
772 .map(|v| self.tcx.mk_int_var(v)),
775 (0..inner.float_unification_table().len())
776 .map(|i| ty::FloatVid { index: i as u32 })
777 .filter(|&vid| inner.float_unification_table().probe_value(vid).is_none())
778 .map(|v| self.tcx.mk_float_var(v)),
785 trace: TypeTrace<'tcx>,
786 param_env: ty::ParamEnv<'tcx>,
787 define_opaque_types: bool,
788 ) -> CombineFields<'a, 'tcx> {
794 obligations: PredicateObligations::new(),
799 /// Clear the "currently in a snapshot" flag, invoke the closure,
800 /// then restore the flag to its original value. This flag is a
801 /// debugging measure designed to detect cases where we start a
802 /// snapshot, create type variables, and register obligations
803 /// which may involve those type variables in the fulfillment cx,
804 /// potentially leaving "dangling type variables" behind.
805 /// In such cases, an assertion will fail when attempting to
806 /// register obligations, within a snapshot. Very useful, much
807 /// better than grovelling through megabytes of `RUSTC_LOG` output.
809 /// HOWEVER, in some cases the flag is unhelpful. In particular, we
810 /// sometimes create a "mini-fulfilment-cx" in which we enroll
811 /// obligations. As long as this fulfillment cx is fully drained
812 /// before we return, this is not a problem, as there won't be any
813 /// escaping obligations in the main cx. In those cases, you can
814 /// use this function.
815 pub fn save_and_restore_in_snapshot_flag<F, R>(&self, func: F) -> R
817 F: FnOnce(&Self) -> R,
819 let flag = self.in_snapshot.replace(false);
820 let result = func(self);
821 self.in_snapshot.set(flag);
825 fn start_snapshot(&self) -> CombinedSnapshot<'a, 'tcx> {
826 debug!("start_snapshot()");
828 let in_snapshot = self.in_snapshot.replace(true);
830 let mut inner = self.inner.borrow_mut();
833 undo_snapshot: inner.undo_log.start_snapshot(),
834 region_constraints_snapshot: inner.unwrap_region_constraints().start_snapshot(),
835 universe: self.universe(),
836 was_in_snapshot: in_snapshot,
837 // Borrow typeck results "in progress" (i.e., during typeck)
838 // to ban writes from within a snapshot to them.
839 _in_progress_typeck_results: self
840 .in_progress_typeck_results
841 .map(|typeck_results| typeck_results.borrow()),
845 #[instrument(skip(self, snapshot), level = "debug")]
846 fn rollback_to(&self, cause: &str, snapshot: CombinedSnapshot<'a, 'tcx>) {
847 let CombinedSnapshot {
849 region_constraints_snapshot,
852 _in_progress_typeck_results,
855 self.in_snapshot.set(was_in_snapshot);
856 self.universe.set(universe);
858 let mut inner = self.inner.borrow_mut();
859 inner.rollback_to(undo_snapshot);
860 inner.unwrap_region_constraints().rollback_to(region_constraints_snapshot);
863 #[instrument(skip(self, snapshot), level = "debug")]
864 fn commit_from(&self, snapshot: CombinedSnapshot<'a, 'tcx>) {
865 let CombinedSnapshot {
867 region_constraints_snapshot: _,
870 _in_progress_typeck_results,
873 self.in_snapshot.set(was_in_snapshot);
875 self.inner.borrow_mut().commit(undo_snapshot);
878 /// Execute `f` and commit the bindings if closure `f` returns `Ok(_)`.
879 #[instrument(skip(self, f), level = "debug")]
880 pub fn commit_if_ok<T, E, F>(&self, f: F) -> Result<T, E>
882 F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> Result<T, E>,
884 let snapshot = self.start_snapshot();
885 let r = f(&snapshot);
886 debug!("commit_if_ok() -- r.is_ok() = {}", r.is_ok());
889 self.commit_from(snapshot);
892 self.rollback_to("commit_if_ok -- error", snapshot);
898 /// Execute `f` then unroll any bindings it creates.
899 #[instrument(skip(self, f), level = "debug")]
900 pub fn probe<R, F>(&self, f: F) -> R
902 F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> R,
904 let snapshot = self.start_snapshot();
905 let r = f(&snapshot);
906 self.rollback_to("probe", snapshot);
910 /// If `should_skip` is true, then execute `f` then unroll any bindings it creates.
911 #[instrument(skip(self, f), level = "debug")]
912 pub fn probe_maybe_skip_leak_check<R, F>(&self, should_skip: bool, f: F) -> R
914 F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> R,
916 let snapshot = self.start_snapshot();
917 let was_skip_leak_check = self.skip_leak_check.get();
919 self.skip_leak_check.set(true);
921 let r = f(&snapshot);
922 self.rollback_to("probe", snapshot);
923 self.skip_leak_check.set(was_skip_leak_check);
927 /// Scan the constraints produced since `snapshot` began and returns:
929 /// - `None` -- if none of them involve "region outlives" constraints
930 /// - `Some(true)` -- if there are `'a: 'b` constraints where `'a` or `'b` is a placeholder
931 /// - `Some(false)` -- if there are `'a: 'b` constraints but none involve placeholders
932 pub fn region_constraints_added_in_snapshot(
934 snapshot: &CombinedSnapshot<'a, 'tcx>,
938 .unwrap_region_constraints()
939 .region_constraints_added_in_snapshot(&snapshot.undo_snapshot)
942 pub fn opaque_types_added_in_snapshot(&self, snapshot: &CombinedSnapshot<'a, 'tcx>) -> bool {
943 self.inner.borrow().undo_log.opaque_types_in_snapshot(&snapshot.undo_snapshot)
946 pub fn add_given(&self, sub: ty::Region<'tcx>, sup: ty::RegionVid) {
947 self.inner.borrow_mut().unwrap_region_constraints().add_given(sub, sup);
950 pub fn can_sub<T>(&self, param_env: ty::ParamEnv<'tcx>, a: T, b: T) -> UnitResult<'tcx>
952 T: at::ToTrace<'tcx>,
954 let origin = &ObligationCause::dummy();
956 self.at(origin, param_env).sub(a, b).map(|InferOk { obligations: _, .. }| {
957 // Ignore obligations, since we are unrolling
958 // everything anyway.
963 pub fn can_eq<T>(&self, param_env: ty::ParamEnv<'tcx>, a: T, b: T) -> UnitResult<'tcx>
965 T: at::ToTrace<'tcx>,
967 let origin = &ObligationCause::dummy();
969 self.at(origin, param_env).eq(a, b).map(|InferOk { obligations: _, .. }| {
970 // Ignore obligations, since we are unrolling
971 // everything anyway.
976 #[instrument(skip(self), level = "debug")]
979 origin: SubregionOrigin<'tcx>,
983 self.inner.borrow_mut().unwrap_region_constraints().make_subregion(origin, a, b);
986 /// Require that the region `r` be equal to one of the regions in
987 /// the set `regions`.
988 #[instrument(skip(self), level = "debug")]
989 pub fn member_constraint(
991 key: ty::OpaqueTypeKey<'tcx>,
992 definition_span: Span,
994 region: ty::Region<'tcx>,
995 in_regions: &Lrc<Vec<ty::Region<'tcx>>>,
997 self.inner.borrow_mut().unwrap_region_constraints().member_constraint(
1006 /// Processes a `Coerce` predicate from the fulfillment context.
1007 /// This is NOT the preferred way to handle coercion, which is to
1008 /// invoke `FnCtxt::coerce` or a similar method (see `coercion.rs`).
1010 /// This method here is actually a fallback that winds up being
1011 /// invoked when `FnCtxt::coerce` encounters unresolved type variables
1012 /// and records a coercion predicate. Presently, this method is equivalent
1013 /// to `subtype_predicate` -- that is, "coercing" `a` to `b` winds up
1014 /// actually requiring `a <: b`. This is of course a valid coercion,
1015 /// but it's not as flexible as `FnCtxt::coerce` would be.
1017 /// (We may refactor this in the future, but there are a number of
1018 /// practical obstacles. Among other things, `FnCtxt::coerce` presently
1019 /// records adjustments that are required on the HIR in order to perform
1020 /// the coercion, and we don't currently have a way to manage that.)
1021 pub fn coerce_predicate(
1023 cause: &ObligationCause<'tcx>,
1024 param_env: ty::ParamEnv<'tcx>,
1025 predicate: ty::PolyCoercePredicate<'tcx>,
1026 ) -> Result<InferResult<'tcx, ()>, (TyVid, TyVid)> {
1027 let subtype_predicate = predicate.map_bound(|p| ty::SubtypePredicate {
1028 a_is_expected: false, // when coercing from `a` to `b`, `b` is expected
1032 self.subtype_predicate(cause, param_env, subtype_predicate)
1035 pub fn subtype_predicate(
1037 cause: &ObligationCause<'tcx>,
1038 param_env: ty::ParamEnv<'tcx>,
1039 predicate: ty::PolySubtypePredicate<'tcx>,
1040 ) -> Result<InferResult<'tcx, ()>, (TyVid, TyVid)> {
1041 // Check for two unresolved inference variables, in which case we can
1042 // make no progress. This is partly a micro-optimization, but it's
1043 // also an opportunity to "sub-unify" the variables. This isn't
1044 // *necessary* to prevent cycles, because they would eventually be sub-unified
1045 // anyhow during generalization, but it helps with diagnostics (we can detect
1046 // earlier that they are sub-unified).
1048 // Note that we can just skip the binders here because
1049 // type variables can't (at present, at
1050 // least) capture any of the things bound by this binder.
1052 // Note that this sub here is not just for diagnostics - it has semantic
1054 let r_a = self.shallow_resolve(predicate.skip_binder().a);
1055 let r_b = self.shallow_resolve(predicate.skip_binder().b);
1056 match (r_a.kind(), r_b.kind()) {
1057 (&ty::Infer(ty::TyVar(a_vid)), &ty::Infer(ty::TyVar(b_vid))) => {
1058 self.inner.borrow_mut().type_variables().sub(a_vid, b_vid);
1059 return Err((a_vid, b_vid));
1064 Ok(self.commit_if_ok(|_snapshot| {
1065 let ty::SubtypePredicate { a_is_expected, a, b } =
1066 self.replace_bound_vars_with_placeholders(predicate);
1068 let ok = self.at(cause, param_env).sub_exp(a_is_expected, a, b)?;
1074 pub fn region_outlives_predicate(
1076 cause: &traits::ObligationCause<'tcx>,
1077 predicate: ty::PolyRegionOutlivesPredicate<'tcx>,
1079 let ty::OutlivesPredicate(r_a, r_b) = self.replace_bound_vars_with_placeholders(predicate);
1081 SubregionOrigin::from_obligation_cause(cause, || RelateRegionParamBound(cause.span));
1082 self.sub_regions(origin, r_b, r_a); // `b : a` ==> `a <= b`
1085 /// Number of type variables created so far.
1086 pub fn num_ty_vars(&self) -> usize {
1087 self.inner.borrow_mut().type_variables().num_vars()
1090 pub fn next_ty_var_id(&self, origin: TypeVariableOrigin) -> TyVid {
1091 self.inner.borrow_mut().type_variables().new_var(self.universe(), origin)
1094 pub fn next_ty_var(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
1095 self.tcx.mk_ty_var(self.next_ty_var_id(origin))
1098 pub fn next_ty_var_id_in_universe(
1100 origin: TypeVariableOrigin,
1101 universe: ty::UniverseIndex,
1103 self.inner.borrow_mut().type_variables().new_var(universe, origin)
1106 pub fn next_ty_var_in_universe(
1108 origin: TypeVariableOrigin,
1109 universe: ty::UniverseIndex,
1111 let vid = self.next_ty_var_id_in_universe(origin, universe);
1112 self.tcx.mk_ty_var(vid)
1115 pub fn next_const_var(&self, ty: Ty<'tcx>, origin: ConstVariableOrigin) -> ty::Const<'tcx> {
1116 self.tcx.mk_const_var(self.next_const_var_id(origin), ty)
1119 pub fn next_const_var_in_universe(
1122 origin: ConstVariableOrigin,
1123 universe: ty::UniverseIndex,
1124 ) -> ty::Const<'tcx> {
1128 .const_unification_table()
1129 .new_key(ConstVarValue { origin, val: ConstVariableValue::Unknown { universe } });
1130 self.tcx.mk_const_var(vid, ty)
1133 pub fn next_const_var_id(&self, origin: ConstVariableOrigin) -> ConstVid<'tcx> {
1134 self.inner.borrow_mut().const_unification_table().new_key(ConstVarValue {
1136 val: ConstVariableValue::Unknown { universe: self.universe() },
1140 fn next_int_var_id(&self) -> IntVid {
1141 self.inner.borrow_mut().int_unification_table().new_key(None)
1144 pub fn next_int_var(&self) -> Ty<'tcx> {
1145 self.tcx.mk_int_var(self.next_int_var_id())
1148 fn next_float_var_id(&self) -> FloatVid {
1149 self.inner.borrow_mut().float_unification_table().new_key(None)
1152 pub fn next_float_var(&self) -> Ty<'tcx> {
1153 self.tcx.mk_float_var(self.next_float_var_id())
1156 /// Creates a fresh region variable with the next available index.
1157 /// The variable will be created in the maximum universe created
1158 /// thus far, allowing it to name any region created thus far.
1159 pub fn next_region_var(&self, origin: RegionVariableOrigin) -> ty::Region<'tcx> {
1160 self.next_region_var_in_universe(origin, self.universe())
1163 /// Creates a fresh region variable with the next available index
1164 /// in the given universe; typically, you can use
1165 /// `next_region_var` and just use the maximal universe.
1166 pub fn next_region_var_in_universe(
1168 origin: RegionVariableOrigin,
1169 universe: ty::UniverseIndex,
1170 ) -> ty::Region<'tcx> {
1172 self.inner.borrow_mut().unwrap_region_constraints().new_region_var(universe, origin);
1173 self.tcx.mk_region(ty::ReVar(region_var))
1176 /// Return the universe that the region `r` was created in. For
1177 /// most regions (e.g., `'static`, named regions from the user,
1178 /// etc) this is the root universe U0. For inference variables or
1179 /// placeholders, however, it will return the universe which which
1180 /// they are associated.
1181 pub fn universe_of_region(&self, r: ty::Region<'tcx>) -> ty::UniverseIndex {
1182 self.inner.borrow_mut().unwrap_region_constraints().universe(r)
1185 /// Number of region variables created so far.
1186 pub fn num_region_vars(&self) -> usize {
1187 self.inner.borrow_mut().unwrap_region_constraints().num_region_vars()
1190 /// Just a convenient wrapper of `next_region_var` for using during NLL.
1191 pub fn next_nll_region_var(&self, origin: NllRegionVariableOrigin) -> ty::Region<'tcx> {
1192 self.next_region_var(RegionVariableOrigin::Nll(origin))
1195 /// Just a convenient wrapper of `next_region_var` for using during NLL.
1196 pub fn next_nll_region_var_in_universe(
1198 origin: NllRegionVariableOrigin,
1199 universe: ty::UniverseIndex,
1200 ) -> ty::Region<'tcx> {
1201 self.next_region_var_in_universe(RegionVariableOrigin::Nll(origin), universe)
1204 pub fn var_for_def(&self, span: Span, param: &ty::GenericParamDef) -> GenericArg<'tcx> {
1206 GenericParamDefKind::Lifetime => {
1207 // Create a region inference variable for the given
1208 // region parameter definition.
1209 self.next_region_var(EarlyBoundRegion(span, param.name)).into()
1211 GenericParamDefKind::Type { .. } => {
1212 // Create a type inference variable for the given
1213 // type parameter definition. The substitutions are
1214 // for actual parameters that may be referred to by
1215 // the default of this type parameter, if it exists.
1216 // e.g., `struct Foo<A, B, C = (A, B)>(...);` when
1217 // used in a path such as `Foo::<T, U>::new()` will
1218 // use an inference variable for `C` with `[T, U]`
1219 // as the substitutions for the default, `(T, U)`.
1220 let ty_var_id = self.inner.borrow_mut().type_variables().new_var(
1222 TypeVariableOrigin {
1223 kind: TypeVariableOriginKind::TypeParameterDefinition(
1231 self.tcx.mk_ty_var(ty_var_id).into()
1233 GenericParamDefKind::Const { .. } => {
1234 let origin = ConstVariableOrigin {
1235 kind: ConstVariableOriginKind::ConstParameterDefinition(
1242 self.inner.borrow_mut().const_unification_table().new_key(ConstVarValue {
1244 val: ConstVariableValue::Unknown { universe: self.universe() },
1246 self.tcx.mk_const_var(const_var_id, self.tcx.type_of(param.def_id)).into()
1251 /// Given a set of generics defined on a type or impl, returns a substitution mapping each
1252 /// type/region parameter to a fresh inference variable.
1253 pub fn fresh_substs_for_item(&self, span: Span, def_id: DefId) -> SubstsRef<'tcx> {
1254 InternalSubsts::for_item(self.tcx, def_id, |param, _| self.var_for_def(span, param))
1257 /// Returns `true` if errors have been reported since this infcx was
1258 /// created. This is sometimes used as a heuristic to skip
1259 /// reporting errors that often occur as a result of earlier
1260 /// errors, but where it's hard to be 100% sure (e.g., unresolved
1261 /// inference variables, regionck errors).
1262 pub fn is_tainted_by_errors(&self) -> bool {
1264 "is_tainted_by_errors(err_count={}, err_count_on_creation={}, \
1265 tainted_by_errors={})",
1266 self.tcx.sess.err_count(),
1267 self.err_count_on_creation,
1268 self.tainted_by_errors.get().is_some()
1271 if self.tcx.sess.err_count() > self.err_count_on_creation {
1272 return true; // errors reported since this infcx was made
1274 self.tainted_by_errors.get().is_some()
1277 /// Set the "tainted by errors" flag to true. We call this when we
1278 /// observe an error from a prior pass.
1279 pub fn set_tainted_by_errors(&self) {
1280 debug!("set_tainted_by_errors()");
1281 self.tainted_by_errors.set(Some(
1282 self.tcx.sess.delay_span_bug(DUMMY_SP, "`InferCtxt` incorrectly tainted by errors"),
1286 pub fn skip_region_resolution(&self) {
1287 let (var_infos, _) = {
1288 let mut inner = self.inner.borrow_mut();
1289 let inner = &mut *inner;
1290 // Note: `inner.region_obligations` may not be empty, because we
1291 // didn't necessarily call `process_registered_region_obligations`.
1292 // This is okay, because that doesn't introduce new vars.
1294 .region_constraint_storage
1296 .expect("regions already resolved")
1297 .with_log(&mut inner.undo_log)
1298 .into_infos_and_data()
1301 let lexical_region_resolutions = LexicalRegionResolutions {
1302 values: rustc_index::vec::IndexVec::from_elem_n(
1303 crate::infer::lexical_region_resolve::VarValue::Value(self.tcx.lifetimes.re_erased),
1308 let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
1309 assert!(old_value.is_none());
1312 /// Process the region constraints and return any any errors that
1313 /// result. After this, no more unification operations should be
1314 /// done -- or the compiler will panic -- but it is legal to use
1315 /// `resolve_vars_if_possible` as well as `fully_resolve`.
1316 pub fn resolve_regions(
1318 outlives_env: &OutlivesEnvironment<'tcx>,
1319 ) -> Vec<RegionResolutionError<'tcx>> {
1320 let (var_infos, data) = {
1321 let mut inner = self.inner.borrow_mut();
1322 let inner = &mut *inner;
1324 self.is_tainted_by_errors() || inner.region_obligations.is_empty(),
1325 "region_obligations not empty: {:#?}",
1326 inner.region_obligations
1329 .region_constraint_storage
1331 .expect("regions already resolved")
1332 .with_log(&mut inner.undo_log)
1333 .into_infos_and_data()
1336 let region_rels = &RegionRelations::new(self.tcx, outlives_env.free_region_map());
1338 let (lexical_region_resolutions, errors) =
1339 lexical_region_resolve::resolve(outlives_env.param_env, region_rels, var_infos, data);
1341 let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
1342 assert!(old_value.is_none());
1347 /// Process the region constraints and report any errors that
1348 /// result. After this, no more unification operations should be
1349 /// done -- or the compiler will panic -- but it is legal to use
1350 /// `resolve_vars_if_possible` as well as `fully_resolve`.
1352 /// Make sure to call [`InferCtxt::process_registered_region_obligations`]
1353 /// first, or preferably use [`InferCtxt::check_region_obligations_and_report_errors`]
1354 /// to do both of these operations together.
1355 pub fn resolve_regions_and_report_errors(
1357 generic_param_scope: LocalDefId,
1358 outlives_env: &OutlivesEnvironment<'tcx>,
1360 let errors = self.resolve_regions(outlives_env);
1362 if !self.is_tainted_by_errors() {
1363 // As a heuristic, just skip reporting region errors
1364 // altogether if other errors have been reported while
1365 // this infcx was in use. This is totally hokey but
1366 // otherwise we have a hard time separating legit region
1367 // errors from silly ones.
1368 self.report_region_errors(generic_param_scope, &errors);
1372 /// Obtains (and clears) the current set of region
1373 /// constraints. The inference context is still usable: further
1374 /// unifications will simply add new constraints.
1376 /// This method is not meant to be used with normal lexical region
1377 /// resolution. Rather, it is used in the NLL mode as a kind of
1378 /// interim hack: basically we run normal type-check and generate
1379 /// region constraints as normal, but then we take them and
1380 /// translate them into the form that the NLL solver
1381 /// understands. See the NLL module for mode details.
1382 pub fn take_and_reset_region_constraints(&self) -> RegionConstraintData<'tcx> {
1384 self.inner.borrow().region_obligations.is_empty(),
1385 "region_obligations not empty: {:#?}",
1386 self.inner.borrow().region_obligations
1389 self.inner.borrow_mut().unwrap_region_constraints().take_and_reset_data()
1392 /// Gives temporary access to the region constraint data.
1393 pub fn with_region_constraints<R>(
1395 op: impl FnOnce(&RegionConstraintData<'tcx>) -> R,
1397 let mut inner = self.inner.borrow_mut();
1398 op(inner.unwrap_region_constraints().data())
1401 pub fn region_var_origin(&self, vid: ty::RegionVid) -> RegionVariableOrigin {
1402 let mut inner = self.inner.borrow_mut();
1403 let inner = &mut *inner;
1405 .region_constraint_storage
1407 .expect("regions already resolved")
1408 .with_log(&mut inner.undo_log)
1412 /// Takes ownership of the list of variable regions. This implies
1413 /// that all the region constraints have already been taken, and
1414 /// hence that `resolve_regions_and_report_errors` can never be
1415 /// called. This is used only during NLL processing to "hand off" ownership
1416 /// of the set of region variables into the NLL region context.
1417 pub fn take_region_var_origins(&self) -> VarInfos {
1418 let mut inner = self.inner.borrow_mut();
1419 let (var_infos, data) = inner
1420 .region_constraint_storage
1422 .expect("regions already resolved")
1423 .with_log(&mut inner.undo_log)
1424 .into_infos_and_data();
1425 assert!(data.is_empty());
1429 pub fn ty_to_string(&self, t: Ty<'tcx>) -> String {
1430 self.resolve_vars_if_possible(t).to_string()
1433 /// If `TyVar(vid)` resolves to a type, return that type. Else, return the
1434 /// universe index of `TyVar(vid)`.
1435 pub fn probe_ty_var(&self, vid: TyVid) -> Result<Ty<'tcx>, ty::UniverseIndex> {
1436 use self::type_variable::TypeVariableValue;
1438 match self.inner.borrow_mut().type_variables().probe(vid) {
1439 TypeVariableValue::Known { value } => Ok(value),
1440 TypeVariableValue::Unknown { universe } => Err(universe),
1444 /// Resolve any type variables found in `value` -- but only one
1445 /// level. So, if the variable `?X` is bound to some type
1446 /// `Foo<?Y>`, then this would return `Foo<?Y>` (but `?Y` may
1447 /// itself be bound to a type).
1449 /// Useful when you only need to inspect the outermost level of
1450 /// the type and don't care about nested types (or perhaps you
1451 /// will be resolving them as well, e.g. in a loop).
1452 pub fn shallow_resolve<T>(&self, value: T) -> T
1454 T: TypeFoldable<'tcx>,
1456 value.fold_with(&mut ShallowResolver { infcx: self })
1459 pub fn root_var(&self, var: ty::TyVid) -> ty::TyVid {
1460 self.inner.borrow_mut().type_variables().root_var(var)
1463 /// Where possible, replaces type/const variables in
1464 /// `value` with their final value. Note that region variables
1465 /// are unaffected. If a type/const variable has not been unified, it
1466 /// is left as is. This is an idempotent operation that does
1467 /// not affect inference state in any way and so you can do it
1469 pub fn resolve_vars_if_possible<T>(&self, value: T) -> T
1471 T: TypeFoldable<'tcx>,
1473 if !value.needs_infer() {
1474 return value; // Avoid duplicated subst-folding.
1476 let mut r = resolve::OpportunisticVarResolver::new(self);
1477 value.fold_with(&mut r)
1480 pub fn resolve_numeric_literals_with_default<T>(&self, value: T) -> T
1482 T: TypeFoldable<'tcx>,
1484 if !value.needs_infer() {
1485 return value; // Avoid duplicated subst-folding.
1487 let mut r = InferenceLiteralEraser { tcx: self.tcx };
1488 value.fold_with(&mut r)
1491 /// Returns the first unresolved variable contained in `T`. In the
1492 /// process of visiting `T`, this will resolve (where possible)
1493 /// type variables in `T`, but it never constructs the final,
1494 /// resolved type, so it's more efficient than
1495 /// `resolve_vars_if_possible()`.
1496 pub fn unresolved_type_vars<T>(&self, value: &T) -> Option<(Ty<'tcx>, Option<Span>)>
1498 T: TypeVisitable<'tcx>,
1500 value.visit_with(&mut resolve::UnresolvedTypeFinder::new(self)).break_value()
1503 pub fn probe_const_var(
1505 vid: ty::ConstVid<'tcx>,
1506 ) -> Result<ty::Const<'tcx>, ty::UniverseIndex> {
1507 match self.inner.borrow_mut().const_unification_table().probe_value(vid).val {
1508 ConstVariableValue::Known { value } => Ok(value),
1509 ConstVariableValue::Unknown { universe } => Err(universe),
1513 pub fn fully_resolve<T: TypeFoldable<'tcx>>(&self, value: T) -> FixupResult<'tcx, T> {
1515 * Attempts to resolve all type/region/const variables in
1516 * `value`. Region inference must have been run already (e.g.,
1517 * by calling `resolve_regions_and_report_errors`). If some
1518 * variable was never unified, an `Err` results.
1520 * This method is idempotent, but it not typically not invoked
1521 * except during the writeback phase.
1524 resolve::fully_resolve(self, value)
1527 // [Note-Type-error-reporting]
1528 // An invariant is that anytime the expected or actual type is Error (the special
1529 // error type, meaning that an error occurred when typechecking this expression),
1530 // this is a derived error. The error cascaded from another error (that was already
1531 // reported), so it's not useful to display it to the user.
1532 // The following methods implement this logic.
1533 // They check if either the actual or expected type is Error, and don't print the error
1534 // in this case. The typechecker should only ever report type errors involving mismatched
1535 // types using one of these methods, and should not call span_err directly for such
1538 pub fn type_error_struct_with_diag<M>(
1542 actual_ty: Ty<'tcx>,
1543 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed>
1545 M: FnOnce(String) -> DiagnosticBuilder<'tcx, ErrorGuaranteed>,
1547 let actual_ty = self.resolve_vars_if_possible(actual_ty);
1548 debug!("type_error_struct_with_diag({:?}, {:?})", sp, actual_ty);
1550 let mut err = mk_diag(self.ty_to_string(actual_ty));
1552 // Don't report an error if actual type is `Error`.
1553 if actual_ty.references_error() {
1554 err.downgrade_to_delayed_bug();
1560 pub fn report_mismatched_types(
1562 cause: &ObligationCause<'tcx>,
1565 err: TypeError<'tcx>,
1566 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
1567 self.report_and_explain_type_error(TypeTrace::types(cause, true, expected, actual), err)
1570 pub fn report_mismatched_consts(
1572 cause: &ObligationCause<'tcx>,
1573 expected: ty::Const<'tcx>,
1574 actual: ty::Const<'tcx>,
1575 err: TypeError<'tcx>,
1576 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
1577 self.report_and_explain_type_error(TypeTrace::consts(cause, true, expected, actual), err)
1580 pub fn replace_bound_vars_with_fresh_vars<T>(
1583 lbrct: LateBoundRegionConversionTime,
1584 value: ty::Binder<'tcx, T>,
1587 T: TypeFoldable<'tcx> + Copy,
1589 if let Some(inner) = value.no_bound_vars() {
1593 struct ToFreshVars<'a, 'tcx> {
1594 infcx: &'a InferCtxt<'a, 'tcx>,
1596 lbrct: LateBoundRegionConversionTime,
1597 map: FxHashMap<ty::BoundVar, ty::GenericArg<'tcx>>,
1600 impl<'tcx> BoundVarReplacerDelegate<'tcx> for ToFreshVars<'_, 'tcx> {
1601 fn replace_region(&mut self, br: ty::BoundRegion) -> ty::Region<'tcx> {
1604 .or_insert_with(|| {
1606 .next_region_var(LateBoundRegion(self.span, br.kind, self.lbrct))
1611 fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx> {
1614 .or_insert_with(|| {
1616 .next_ty_var(TypeVariableOrigin {
1617 kind: TypeVariableOriginKind::MiscVariable,
1624 fn replace_const(&mut self, bv: ty::BoundVar, ty: Ty<'tcx>) -> ty::Const<'tcx> {
1627 .or_insert_with(|| {
1631 ConstVariableOrigin {
1632 kind: ConstVariableOriginKind::MiscVariable,
1641 let delegate = ToFreshVars { infcx: self, span, lbrct, map: Default::default() };
1642 self.tcx.replace_bound_vars_uncached(value, delegate)
1645 /// See the [`region_constraints::RegionConstraintCollector::verify_generic_bound`] method.
1646 pub fn verify_generic_bound(
1648 origin: SubregionOrigin<'tcx>,
1649 kind: GenericKind<'tcx>,
1650 a: ty::Region<'tcx>,
1651 bound: VerifyBound<'tcx>,
1653 debug!("verify_generic_bound({:?}, {:?} <: {:?})", kind, a, bound);
1657 .unwrap_region_constraints()
1658 .verify_generic_bound(origin, kind, a, bound);
1661 /// Obtains the latest type of the given closure; this may be a
1662 /// closure in the current function, in which case its
1663 /// `ClosureKind` may not yet be known.
1664 pub fn closure_kind(&self, closure_substs: SubstsRef<'tcx>) -> Option<ty::ClosureKind> {
1665 let closure_kind_ty = closure_substs.as_closure().kind_ty();
1666 let closure_kind_ty = self.shallow_resolve(closure_kind_ty);
1667 closure_kind_ty.to_opt_closure_kind()
1670 /// Clears the selection, evaluation, and projection caches. This is useful when
1671 /// repeatedly attempting to select an `Obligation` while changing only
1672 /// its `ParamEnv`, since `FulfillmentContext` doesn't use probing.
1673 pub fn clear_caches(&self) {
1674 self.selection_cache.clear();
1675 self.evaluation_cache.clear();
1676 self.inner.borrow_mut().projection_cache().clear();
1679 pub fn universe(&self) -> ty::UniverseIndex {
1683 /// Creates and return a fresh universe that extends all previous
1684 /// universes. Updates `self.universe` to that new universe.
1685 pub fn create_next_universe(&self) -> ty::UniverseIndex {
1686 let u = self.universe.get().next_universe();
1687 self.universe.set(u);
1691 pub fn try_const_eval_resolve(
1693 param_env: ty::ParamEnv<'tcx>,
1694 unevaluated: ty::UnevaluatedConst<'tcx>,
1697 ) -> Result<ty::Const<'tcx>, ErrorHandled> {
1698 match self.const_eval_resolve(param_env, unevaluated, span) {
1699 Ok(Some(val)) => Ok(ty::Const::from_value(self.tcx, val, ty)),
1702 let def_id = unevaluated.def.did;
1704 tcx.def_span(def_id),
1705 "unable to construct a constant value for the unevaluated constant {:?}",
1709 Err(err) => Err(err),
1713 /// Resolves and evaluates a constant.
1715 /// The constant can be located on a trait like `<A as B>::C`, in which case the given
1716 /// substitutions and environment are used to resolve the constant. Alternatively if the
1717 /// constant has generic parameters in scope the substitutions are used to evaluate the value of
1718 /// the constant. For example in `fn foo<T>() { let _ = [0; bar::<T>()]; }` the repeat count
1719 /// constant `bar::<T>()` requires a substitution for `T`, if the substitution for `T` is still
1720 /// too generic for the constant to be evaluated then `Err(ErrorHandled::TooGeneric)` is
1723 /// This handles inferences variables within both `param_env` and `substs` by
1724 /// performing the operation on their respective canonical forms.
1725 #[instrument(skip(self), level = "debug")]
1726 pub fn const_eval_resolve(
1728 mut param_env: ty::ParamEnv<'tcx>,
1729 unevaluated: ty::UnevaluatedConst<'tcx>,
1731 ) -> EvalToValTreeResult<'tcx> {
1732 let mut substs = self.resolve_vars_if_possible(unevaluated.substs);
1735 // Postpone the evaluation of constants whose substs depend on inference
1737 if substs.has_non_region_infer() {
1738 let ac = AbstractConst::new(self.tcx, unevaluated);
1741 substs = InternalSubsts::identity_for_item(self.tcx, unevaluated.def.did);
1742 param_env = self.tcx.param_env(unevaluated.def.did);
1745 if ct.unify_failure_kind(self.tcx) == FailureKind::Concrete {
1746 substs = replace_param_and_infer_substs_with_placeholder(self.tcx, substs);
1748 return Err(ErrorHandled::TooGeneric);
1751 Err(guar) => return Err(ErrorHandled::Reported(guar)),
1755 let param_env_erased = self.tcx.erase_regions(param_env);
1756 let substs_erased = self.tcx.erase_regions(substs);
1757 debug!(?param_env_erased);
1758 debug!(?substs_erased);
1760 let unevaluated = ty::UnevaluatedConst { def: unevaluated.def, substs: substs_erased };
1762 // The return value is the evaluated value which doesn't contain any reference to inference
1763 // variables, thus we don't need to substitute back the original values.
1764 self.tcx.const_eval_resolve_for_typeck(param_env_erased, unevaluated, span)
1767 /// `ty_or_const_infer_var_changed` is equivalent to one of these two:
1768 /// * `shallow_resolve(ty) != ty` (where `ty.kind = ty::Infer(_)`)
1769 /// * `shallow_resolve(ct) != ct` (where `ct.kind = ty::ConstKind::Infer(_)`)
1771 /// However, `ty_or_const_infer_var_changed` is more efficient. It's always
1772 /// inlined, despite being large, because it has only two call sites that
1773 /// are extremely hot (both in `traits::fulfill`'s checking of `stalled_on`
1774 /// inference variables), and it handles both `Ty` and `ty::Const` without
1775 /// having to resort to storing full `GenericArg`s in `stalled_on`.
1777 pub fn ty_or_const_infer_var_changed(&self, infer_var: TyOrConstInferVar<'tcx>) -> bool {
1779 TyOrConstInferVar::Ty(v) => {
1780 use self::type_variable::TypeVariableValue;
1782 // If `inlined_probe` returns a `Known` value, it never equals
1783 // `ty::Infer(ty::TyVar(v))`.
1784 match self.inner.borrow_mut().type_variables().inlined_probe(v) {
1785 TypeVariableValue::Unknown { .. } => false,
1786 TypeVariableValue::Known { .. } => true,
1790 TyOrConstInferVar::TyInt(v) => {
1791 // If `inlined_probe_value` returns a value it's always a
1792 // `ty::Int(_)` or `ty::UInt(_)`, which never matches a
1794 self.inner.borrow_mut().int_unification_table().inlined_probe_value(v).is_some()
1797 TyOrConstInferVar::TyFloat(v) => {
1798 // If `probe_value` returns a value it's always a
1799 // `ty::Float(_)`, which never matches a `ty::Infer(_)`.
1801 // Not `inlined_probe_value(v)` because this call site is colder.
1802 self.inner.borrow_mut().float_unification_table().probe_value(v).is_some()
1805 TyOrConstInferVar::Const(v) => {
1806 // If `probe_value` returns a `Known` value, it never equals
1807 // `ty::ConstKind::Infer(ty::InferConst::Var(v))`.
1809 // Not `inlined_probe_value(v)` because this call site is colder.
1810 match self.inner.borrow_mut().const_unification_table().probe_value(v).val {
1811 ConstVariableValue::Unknown { .. } => false,
1812 ConstVariableValue::Known { .. } => true,
1819 /// Helper for `ty_or_const_infer_var_changed` (see comment on that), currently
1820 /// used only for `traits::fulfill`'s list of `stalled_on` inference variables.
1821 #[derive(Copy, Clone, Debug)]
1822 pub enum TyOrConstInferVar<'tcx> {
1823 /// Equivalent to `ty::Infer(ty::TyVar(_))`.
1825 /// Equivalent to `ty::Infer(ty::IntVar(_))`.
1827 /// Equivalent to `ty::Infer(ty::FloatVar(_))`.
1830 /// Equivalent to `ty::ConstKind::Infer(ty::InferConst::Var(_))`.
1831 Const(ConstVid<'tcx>),
1834 impl<'tcx> TyOrConstInferVar<'tcx> {
1835 /// Tries to extract an inference variable from a type or a constant, returns `None`
1836 /// for types other than `ty::Infer(_)` (or `InferTy::Fresh*`) and
1837 /// for constants other than `ty::ConstKind::Infer(_)` (or `InferConst::Fresh`).
1838 pub fn maybe_from_generic_arg(arg: GenericArg<'tcx>) -> Option<Self> {
1839 match arg.unpack() {
1840 GenericArgKind::Type(ty) => Self::maybe_from_ty(ty),
1841 GenericArgKind::Const(ct) => Self::maybe_from_const(ct),
1842 GenericArgKind::Lifetime(_) => None,
1846 /// Tries to extract an inference variable from a type, returns `None`
1847 /// for types other than `ty::Infer(_)` (or `InferTy::Fresh*`).
1848 fn maybe_from_ty(ty: Ty<'tcx>) -> Option<Self> {
1850 ty::Infer(ty::TyVar(v)) => Some(TyOrConstInferVar::Ty(v)),
1851 ty::Infer(ty::IntVar(v)) => Some(TyOrConstInferVar::TyInt(v)),
1852 ty::Infer(ty::FloatVar(v)) => Some(TyOrConstInferVar::TyFloat(v)),
1857 /// Tries to extract an inference variable from a constant, returns `None`
1858 /// for constants other than `ty::ConstKind::Infer(_)` (or `InferConst::Fresh`).
1859 fn maybe_from_const(ct: ty::Const<'tcx>) -> Option<Self> {
1861 ty::ConstKind::Infer(InferConst::Var(v)) => Some(TyOrConstInferVar::Const(v)),
1867 /// Replace `{integer}` with `i32` and `{float}` with `f64`.
1868 /// Used only for diagnostics.
1869 struct InferenceLiteralEraser<'tcx> {
1873 impl<'tcx> TypeFolder<'tcx> for InferenceLiteralEraser<'tcx> {
1874 fn tcx(&self) -> TyCtxt<'tcx> {
1878 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
1880 ty::Infer(ty::IntVar(_) | ty::FreshIntTy(_)) => self.tcx.types.i32,
1881 ty::Infer(ty::FloatVar(_) | ty::FreshFloatTy(_)) => self.tcx.types.f64,
1882 _ => ty.super_fold_with(self),
1887 struct ShallowResolver<'a, 'tcx> {
1888 infcx: &'a InferCtxt<'a, 'tcx>,
1891 impl<'a, 'tcx> TypeFolder<'tcx> for ShallowResolver<'a, 'tcx> {
1892 fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
1896 /// If `ty` is a type variable of some kind, resolve it one level
1897 /// (but do not resolve types found in the result). If `typ` is
1898 /// not a type variable, just return it unmodified.
1899 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
1901 ty::Infer(ty::TyVar(v)) => {
1902 // Not entirely obvious: if `typ` is a type variable,
1903 // it can be resolved to an int/float variable, which
1904 // can then be recursively resolved, hence the
1905 // recursion. Note though that we prevent type
1906 // variables from unifying to other type variables
1907 // directly (though they may be embedded
1908 // structurally), and we prevent cycles in any case,
1909 // so this recursion should always be of very limited
1912 // Note: if these two lines are combined into one we get
1913 // dynamic borrow errors on `self.inner`.
1914 let known = self.infcx.inner.borrow_mut().type_variables().probe(v).known();
1915 known.map_or(ty, |t| self.fold_ty(t))
1918 ty::Infer(ty::IntVar(v)) => self
1922 .int_unification_table()
1924 .map_or(ty, |v| v.to_type(self.infcx.tcx)),
1926 ty::Infer(ty::FloatVar(v)) => self
1930 .float_unification_table()
1932 .map_or(ty, |v| v.to_type(self.infcx.tcx)),
1938 fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
1939 if let ty::ConstKind::Infer(InferConst::Var(vid)) = ct.kind() {
1943 .const_unification_table()
1954 impl<'tcx> TypeTrace<'tcx> {
1955 pub fn span(&self) -> Span {
1960 cause: &ObligationCause<'tcx>,
1961 a_is_expected: bool,
1964 ) -> TypeTrace<'tcx> {
1966 cause: cause.clone(),
1967 values: Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
1971 pub fn poly_trait_refs(
1972 cause: &ObligationCause<'tcx>,
1973 a_is_expected: bool,
1974 a: ty::PolyTraitRef<'tcx>,
1975 b: ty::PolyTraitRef<'tcx>,
1976 ) -> TypeTrace<'tcx> {
1978 cause: cause.clone(),
1979 values: PolyTraitRefs(ExpectedFound::new(a_is_expected, a.into(), b.into())),
1984 cause: &ObligationCause<'tcx>,
1985 a_is_expected: bool,
1988 ) -> TypeTrace<'tcx> {
1990 cause: cause.clone(),
1991 values: Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
1996 impl<'tcx> SubregionOrigin<'tcx> {
1997 pub fn span(&self) -> Span {
1999 Subtype(ref a) => a.span(),
2000 RelateObjectBound(a) => a,
2001 RelateParamBound(a, ..) => a,
2002 RelateRegionParamBound(a) => a,
2004 ReborrowUpvar(a, _) => a,
2005 DataBorrowed(_, a) => a,
2006 ReferenceOutlivesReferent(_, a) => a,
2007 CompareImplItemObligation { span, .. } => span,
2008 AscribeUserTypeProvePredicate(span) => span,
2009 CheckAssociatedTypeBounds { ref parent, .. } => parent.span(),
2013 pub fn from_obligation_cause<F>(cause: &traits::ObligationCause<'tcx>, default: F) -> Self
2015 F: FnOnce() -> Self,
2017 match *cause.code() {
2018 traits::ObligationCauseCode::ReferenceOutlivesReferent(ref_type) => {
2019 SubregionOrigin::ReferenceOutlivesReferent(ref_type, cause.span)
2022 traits::ObligationCauseCode::CompareImplItemObligation {
2026 } => SubregionOrigin::CompareImplItemObligation {
2032 traits::ObligationCauseCode::CheckAssociatedTypeBounds {
2035 } => SubregionOrigin::CheckAssociatedTypeBounds {
2038 parent: Box::new(default()),
2041 traits::ObligationCauseCode::AscribeUserTypeProvePredicate(span) => {
2042 SubregionOrigin::AscribeUserTypeProvePredicate(span)
2050 impl RegionVariableOrigin {
2051 pub fn span(&self) -> Span {
2058 | EarlyBoundRegion(a, ..)
2059 | LateBoundRegion(a, ..)
2060 | UpvarRegion(_, a) => a,
2061 Nll(..) => bug!("NLL variable used with `span`"),
2066 /// Replaces substs that reference param or infer variables with suitable
2067 /// placeholders. This function is meant to remove these param and infer
2068 /// substs when they're not actually needed to evaluate a constant.
2069 fn replace_param_and_infer_substs_with_placeholder<'tcx>(
2071 substs: SubstsRef<'tcx>,
2072 ) -> SubstsRef<'tcx> {
2073 tcx.mk_substs(substs.iter().enumerate().map(|(idx, arg)| {
2074 match arg.unpack() {
2075 GenericArgKind::Type(_) if arg.has_non_region_param() || arg.has_non_region_infer() => {
2076 tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
2077 universe: ty::UniverseIndex::ROOT,
2078 name: ty::BoundVar::from_usize(idx),
2082 GenericArgKind::Const(ct) if ct.has_non_region_infer() || ct.has_non_region_param() => {
2084 // If the type references param or infer, replace that too...
2085 if ty.has_non_region_param() || ty.has_non_region_infer() {
2086 bug!("const `{ct}`'s type should not reference params or types");
2088 tcx.mk_const(ty::ConstS {
2090 kind: ty::ConstKind::Placeholder(ty::PlaceholderConst {
2091 universe: ty::UniverseIndex::ROOT,
2092 name: ty::BoundVar::from_usize(idx),