1 //! See the Book for more information.
3 pub use self::freshen::TypeFreshener;
4 pub use self::LateBoundRegionConversionTime::*;
5 pub use self::RegionVariableOrigin::*;
6 pub use self::SubregionOrigin::*;
7 pub use self::ValuePairs::*;
9 use crate::traits::{self, ObligationCause, PredicateObligations, TraitEngine};
12 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
13 use rustc_data_structures::snapshot_vec as sv;
14 use rustc_data_structures::sync::Lrc;
15 use rustc_data_structures::undo_log::{Rollback, Snapshots, UndoLogs};
16 use rustc_data_structures::unify as ut;
17 use rustc_errors::DiagnosticBuilder;
19 use rustc_hir::def_id::{DefId, LocalDefId};
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::middle::region;
24 use rustc_middle::mir;
25 use rustc_middle::mir::interpret::ConstEvalResult;
26 use rustc_middle::traits::select;
27 use rustc_middle::ty::error::{ExpectedFound, TypeError, UnconstrainedNumeric};
28 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder};
29 use rustc_middle::ty::relate::RelateResult;
30 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, SubstsRef};
31 pub use rustc_middle::ty::IntVarValue;
32 use rustc_middle::ty::{self, GenericParamDefKind, InferConst, Ty, TyCtxt};
33 use rustc_middle::ty::{ConstVid, FloatVid, IntVid, TyVid};
34 use rustc_session::config::BorrowckMode;
35 use rustc_span::symbol::Symbol;
38 use std::cell::{Cell, Ref, RefCell};
39 use std::collections::BTreeMap;
41 use std::marker::PhantomData;
43 use self::combine::CombineFields;
44 use self::free_regions::RegionRelations;
45 use self::lexical_region_resolve::LexicalRegionResolutions;
46 use self::outlives::env::OutlivesEnvironment;
47 use self::region_constraints::{GenericKind, RegionConstraintData, VarInfos, VerifyBound};
48 use self::region_constraints::{
49 RegionConstraintCollector, RegionConstraintStorage, RegionSnapshot,
51 use self::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
57 pub mod error_reporting;
64 mod lexical_region_resolve;
68 pub mod region_constraints;
71 pub mod type_variable;
73 use crate::infer::canonical::OriginalQueryValues;
74 pub use rustc_middle::infer::unify_key;
78 pub struct InferOk<'tcx, T> {
80 pub obligations: PredicateObligations<'tcx>,
82 pub type InferResult<'tcx, T> = Result<InferOk<'tcx, T>, TypeError<'tcx>>;
84 pub type Bound<T> = Option<T>;
85 pub type UnitResult<'tcx> = RelateResult<'tcx, ()>; // "unify result"
86 pub type FixupResult<'tcx, T> = Result<T, FixupError<'tcx>>; // "fixup result"
88 /// How we should handle region solving.
90 /// This is used so that the region values inferred by HIR region solving are
91 /// not exposed, and so that we can avoid doing work in HIR typeck that MIR
92 /// typeck will also do.
93 #[derive(Copy, Clone, Debug)]
94 pub enum RegionckMode {
95 /// The default mode: report region errors, don't erase regions.
97 /// Erase the results of region after solving.
99 /// A flag that is used to suppress region errors, when we are doing
100 /// region checks that the NLL borrow checker will also do -- it might
102 suppress_errors: bool,
106 impl Default for RegionckMode {
107 fn default() -> Self {
113 pub fn suppressed(self) -> bool {
115 Self::Solve => false,
116 Self::Erase { suppress_errors } => suppress_errors,
120 /// Indicates that the MIR borrowck will repeat these region
121 /// checks, so we should ignore errors if NLL is (unconditionally)
123 pub fn for_item_body(tcx: TyCtxt<'_>) -> Self {
124 // FIXME(Centril): Once we actually remove `::Migrate` also make
125 // this always `true` and then proceed to eliminate the dead code.
126 match tcx.borrowck_mode() {
127 // If we're on Migrate mode, report AST region errors
128 BorrowckMode::Migrate => RegionckMode::Erase { suppress_errors: false },
130 // If we're on MIR, don't report AST region errors as they should be reported by NLL
131 BorrowckMode::Mir => RegionckMode::Erase { suppress_errors: true },
136 /// This type contains all the things within `InferCtxt` that sit within a
137 /// `RefCell` and are involved with taking/rolling back snapshots. Snapshot
138 /// operations are hot enough that we want only one call to `borrow_mut` per
139 /// call to `start_snapshot` and `rollback_to`.
140 pub struct InferCtxtInner<'tcx> {
141 /// Cache for projections. This cache is snapshotted along with the infcx.
143 /// Public so that `traits::project` can use it.
144 pub projection_cache: traits::ProjectionCacheStorage<'tcx>,
146 /// We instantiate `UnificationTable` with `bounds<Ty>` because the types
147 /// that might instantiate a general type variable have an order,
148 /// represented by its upper and lower bounds.
149 type_variables: type_variable::TypeVariableStorage<'tcx>,
150 undo_log: Logs<'tcx>,
152 /// Map from const parameter variable to the kind of const it represents.
153 const_unification_table: ut::UnificationStorage<ty::ConstVid<'tcx>>,
155 /// Map from integral variable to the kind of integer it represents.
156 int_unification_table: ut::UnificationStorage<ty::IntVid>,
158 /// Map from floating variable to the kind of float it represents.
159 float_unification_table: ut::UnificationStorage<ty::FloatVid>,
161 /// Tracks the set of region variables and the constraints between them.
162 /// This is initially `Some(_)` but when
163 /// `resolve_regions_and_report_errors` is invoked, this gets set to `None`
164 /// -- further attempts to perform unification, etc., may fail if new
165 /// region constraints would've been added.
166 region_constraints: Option<RegionConstraintStorage<'tcx>>,
168 /// A set of constraints that regionck must validate. Each
169 /// constraint has the form `T:'a`, meaning "some type `T` must
170 /// outlive the lifetime 'a". These constraints derive from
171 /// instantiated type parameters. So if you had a struct defined
174 /// struct Foo<T:'static> { ... }
176 /// then in some expression `let x = Foo { ... }` it will
177 /// instantiate the type parameter `T` with a fresh type `$0`. At
178 /// the same time, it will record a region obligation of
179 /// `$0:'static`. This will get checked later by regionck. (We
180 /// can't generally check these things right away because we have
181 /// to wait until types are resolved.)
183 /// These are stored in a map keyed to the id of the innermost
184 /// enclosing fn body / static initializer expression. This is
185 /// because the location where the obligation was incurred can be
186 /// relevant with respect to which sublifetime assumptions are in
187 /// place. The reason that we store under the fn-id, and not
188 /// something more fine-grained, is so that it is easier for
189 /// regionck to be sure that it has found *all* the region
190 /// obligations (otherwise, it's easy to fail to walk to a
191 /// particular node-id).
193 /// Before running `resolve_regions_and_report_errors`, the creator
194 /// of the inference context is expected to invoke
195 /// `process_region_obligations` (defined in `self::region_obligations`)
196 /// for each body-id in this map, which will process the
197 /// obligations within. This is expected to be done 'late enough'
198 /// that all type inference variables have been bound and so forth.
199 pub region_obligations: Vec<(hir::HirId, RegionObligation<'tcx>)>,
202 impl<'tcx> InferCtxtInner<'tcx> {
203 fn new() -> InferCtxtInner<'tcx> {
205 projection_cache: Default::default(),
206 type_variables: type_variable::TypeVariableStorage::new(),
207 undo_log: Logs::default(),
208 const_unification_table: ut::UnificationStorage::new(),
209 int_unification_table: ut::UnificationStorage::new(),
210 float_unification_table: ut::UnificationStorage::new(),
211 region_constraints: Some(RegionConstraintStorage::new()),
212 region_obligations: vec![],
216 pub(crate) fn projection_cache(&mut self) -> traits::ProjectionCache<'tcx, '_> {
217 self.projection_cache.with_log(&mut self.undo_log)
220 fn type_variables(&mut self) -> type_variable::TypeVariableTable<'tcx, '_> {
221 self.type_variables.with_log(&mut self.undo_log)
224 fn int_unification_table(
226 ) -> ut::UnificationTable<
227 ut::InPlace<ty::IntVid, &mut ut::UnificationStorage<ty::IntVid>, &mut Logs<'tcx>>,
229 ut::UnificationTable::with_log(&mut self.int_unification_table, &mut self.undo_log)
232 fn float_unification_table(
234 ) -> ut::UnificationTable<
235 ut::InPlace<ty::FloatVid, &mut ut::UnificationStorage<ty::FloatVid>, &mut Logs<'tcx>>,
237 ut::UnificationTable::with_log(&mut self.float_unification_table, &mut self.undo_log)
240 fn const_unification_table(
242 ) -> ut::UnificationTable<
245 &mut ut::UnificationStorage<ty::ConstVid<'tcx>>,
249 ut::UnificationTable::with_log(&mut self.const_unification_table, &mut self.undo_log)
252 pub fn unwrap_region_constraints(&mut self) -> RegionConstraintCollector<'tcx, '_> {
253 self.region_constraints
255 .expect("region constraints already solved")
256 .with_log(&mut self.undo_log)
260 pub struct Snapshot<'tcx> {
262 _marker: PhantomData<&'tcx ()>,
265 pub(crate) enum UndoLog<'tcx> {
266 TypeVariables(type_variable::UndoLog<'tcx>),
267 ConstUnificationTable(sv::UndoLog<ut::Delegate<ty::ConstVid<'tcx>>>),
268 IntUnificationTable(sv::UndoLog<ut::Delegate<ty::IntVid>>),
269 FloatUnificationTable(sv::UndoLog<ut::Delegate<ty::FloatVid>>),
270 RegionConstraintCollector(region_constraints::UndoLog<'tcx>),
271 RegionUnificationTable(sv::UndoLog<ut::Delegate<ty::RegionVid>>),
272 ProjectionCache(traits::UndoLog<'tcx>),
275 impl<'tcx> From<region_constraints::UndoLog<'tcx>> for UndoLog<'tcx> {
276 fn from(l: region_constraints::UndoLog<'tcx>) -> Self {
277 UndoLog::RegionConstraintCollector(l)
281 impl<'tcx> From<sv::UndoLog<ut::Delegate<type_variable::TyVidEqKey<'tcx>>>> for UndoLog<'tcx> {
282 fn from(l: sv::UndoLog<ut::Delegate<type_variable::TyVidEqKey<'tcx>>>) -> Self {
283 UndoLog::TypeVariables(type_variable::UndoLog::EqRelation(l))
287 impl<'tcx> From<sv::UndoLog<ut::Delegate<ty::TyVid>>> for UndoLog<'tcx> {
288 fn from(l: sv::UndoLog<ut::Delegate<ty::TyVid>>) -> Self {
289 UndoLog::TypeVariables(type_variable::UndoLog::SubRelation(l))
293 impl<'tcx> From<sv::UndoLog<type_variable::Delegate>> for UndoLog<'tcx> {
294 fn from(l: sv::UndoLog<type_variable::Delegate>) -> Self {
295 UndoLog::TypeVariables(type_variable::UndoLog::Values(l))
299 impl<'tcx> From<type_variable::Instantiate> for UndoLog<'tcx> {
300 fn from(l: type_variable::Instantiate) -> Self {
301 UndoLog::TypeVariables(type_variable::UndoLog::from(l))
305 impl From<type_variable::UndoLog<'tcx>> for UndoLog<'tcx> {
306 fn from(t: type_variable::UndoLog<'tcx>) -> Self {
307 Self::TypeVariables(t)
311 impl<'tcx> From<sv::UndoLog<ut::Delegate<ty::ConstVid<'tcx>>>> for UndoLog<'tcx> {
312 fn from(l: sv::UndoLog<ut::Delegate<ty::ConstVid<'tcx>>>) -> Self {
313 Self::ConstUnificationTable(l)
317 impl<'tcx> From<sv::UndoLog<ut::Delegate<ty::IntVid>>> for UndoLog<'tcx> {
318 fn from(l: sv::UndoLog<ut::Delegate<ty::IntVid>>) -> Self {
319 Self::IntUnificationTable(l)
323 impl<'tcx> From<sv::UndoLog<ut::Delegate<ty::FloatVid>>> for UndoLog<'tcx> {
324 fn from(l: sv::UndoLog<ut::Delegate<ty::FloatVid>>) -> Self {
325 Self::FloatUnificationTable(l)
329 impl<'tcx> From<sv::UndoLog<ut::Delegate<ty::RegionVid>>> for UndoLog<'tcx> {
330 fn from(l: sv::UndoLog<ut::Delegate<ty::RegionVid>>) -> Self {
331 Self::RegionUnificationTable(l)
335 impl<'tcx> From<traits::UndoLog<'tcx>> for UndoLog<'tcx> {
336 fn from(l: traits::UndoLog<'tcx>) -> Self {
337 Self::ProjectionCache(l)
341 pub(crate) type UnificationTable<'a, 'tcx, T> =
342 ut::UnificationTable<ut::InPlace<T, &'a mut ut::UnificationStorage<T>, &'a mut Logs<'tcx>>>;
344 struct RollbackView<'tcx, 'a> {
345 type_variables: type_variable::RollbackView<'tcx, 'a>,
346 const_unification_table: &'a mut ut::UnificationStorage<ty::ConstVid<'tcx>>,
347 int_unification_table: &'a mut ut::UnificationStorage<ty::IntVid>,
348 float_unification_table: &'a mut ut::UnificationStorage<ty::FloatVid>,
349 region_constraints: &'a mut RegionConstraintStorage<'tcx>,
350 projection_cache: &'a mut traits::ProjectionCacheStorage<'tcx>,
353 impl<'tcx> Rollback<UndoLog<'tcx>> for RollbackView<'tcx, '_> {
354 fn reverse(&mut self, undo: UndoLog<'tcx>) {
356 UndoLog::TypeVariables(undo) => self.type_variables.reverse(undo),
357 UndoLog::ConstUnificationTable(undo) => self.const_unification_table.reverse(undo),
358 UndoLog::IntUnificationTable(undo) => self.int_unification_table.reverse(undo),
359 UndoLog::FloatUnificationTable(undo) => self.float_unification_table.reverse(undo),
360 UndoLog::RegionConstraintCollector(undo) => self.region_constraints.reverse(undo),
361 UndoLog::RegionUnificationTable(undo) => {
362 self.region_constraints.unification_table.reverse(undo)
364 UndoLog::ProjectionCache(undo) => self.projection_cache.reverse(undo),
369 pub(crate) struct Logs<'tcx> {
370 logs: Vec<UndoLog<'tcx>>,
371 num_open_snapshots: usize,
374 impl Default for Logs<'_> {
375 fn default() -> Self {
376 Self { logs: Default::default(), num_open_snapshots: Default::default() }
380 impl<'tcx, T> UndoLogs<T> for Logs<'tcx>
382 UndoLog<'tcx>: From<T>,
384 fn num_open_snapshots(&self) -> usize {
385 self.num_open_snapshots
387 fn push(&mut self, undo: T) {
388 if self.in_snapshot() {
389 self.logs.push(undo.into())
392 fn clear(&mut self) {
394 self.num_open_snapshots = 0;
396 fn extend<J>(&mut self, undos: J)
399 J: IntoIterator<Item = T>,
401 if self.in_snapshot() {
402 self.logs.extend(undos.into_iter().map(UndoLog::from))
407 impl<'tcx> Snapshots<UndoLog<'tcx>> for Logs<'tcx> {
408 type Snapshot = Snapshot<'tcx>;
409 fn actions_since_snapshot(&self, snapshot: &Self::Snapshot) -> &[UndoLog<'tcx>] {
410 &self.logs[snapshot.undo_len..]
413 fn start_snapshot(&mut self) -> Self::Snapshot {
417 fn rollback_to<R>(&mut self, values: impl FnOnce() -> R, snapshot: Self::Snapshot)
419 R: Rollback<UndoLog<'tcx>>,
421 debug!("rollback_to({})", snapshot.undo_len);
422 self.assert_open_snapshot(&snapshot);
424 if self.logs.len() > snapshot.undo_len {
425 let mut values = values();
426 while self.logs.len() > snapshot.undo_len {
427 values.reverse(self.logs.pop().unwrap());
431 if self.num_open_snapshots == 1 {
432 // The root snapshot. It's safe to clear the undo log because
433 // there's no snapshot further out that we might need to roll back
435 assert!(snapshot.undo_len == 0);
439 self.num_open_snapshots -= 1;
442 fn commit(&mut self, snapshot: Self::Snapshot) {
443 debug!("commit({})", snapshot.undo_len);
445 if self.num_open_snapshots == 1 {
446 // The root snapshot. It's safe to clear the undo log because
447 // there's no snapshot further out that we might need to roll back
449 assert!(snapshot.undo_len == 0);
453 self.num_open_snapshots -= 1;
457 impl<'tcx> Logs<'tcx> {
458 pub(crate) fn region_constraints(
461 ) -> impl Iterator<Item = &'_ region_constraints::UndoLog<'tcx>> + Clone {
462 self.logs[after..].iter().filter_map(|log| match log {
463 UndoLog::RegionConstraintCollector(log) => Some(log),
468 fn assert_open_snapshot(&self, snapshot: &Snapshot<'tcx>) {
469 // Failures here may indicate a failure to follow a stack discipline.
470 assert!(self.logs.len() >= snapshot.undo_len);
471 assert!(self.num_open_snapshots > 0);
475 pub struct InferCtxt<'a, 'tcx> {
476 pub tcx: TyCtxt<'tcx>,
478 /// During type-checking/inference of a body, `in_progress_tables`
479 /// contains a reference to the tables being built up, which are
480 /// used for reading closure kinds/signatures as they are inferred,
481 /// and for error reporting logic to read arbitrary node types.
482 pub in_progress_tables: Option<&'a RefCell<ty::TypeckTables<'tcx>>>,
484 pub inner: RefCell<InferCtxtInner<'tcx>>,
486 /// If set, this flag causes us to skip the 'leak check' during
487 /// higher-ranked subtyping operations. This flag is a temporary one used
488 /// to manage the removal of the leak-check: for the time being, we still run the
489 /// leak-check, but we issue warnings. This flag can only be set to true
490 /// when entering a snapshot.
491 skip_leak_check: Cell<bool>,
493 /// Once region inference is done, the values for each variable.
494 lexical_region_resolutions: RefCell<Option<LexicalRegionResolutions<'tcx>>>,
496 /// Caches the results of trait selection. This cache is used
497 /// for things that have to do with the parameters in scope.
498 pub selection_cache: select::SelectionCache<'tcx>,
500 /// Caches the results of trait evaluation.
501 pub evaluation_cache: select::EvaluationCache<'tcx>,
503 /// the set of predicates on which errors have been reported, to
504 /// avoid reporting the same error twice.
505 pub reported_trait_errors: RefCell<FxHashMap<Span, Vec<ty::Predicate<'tcx>>>>,
507 pub reported_closure_mismatch: RefCell<FxHashSet<(Span, Option<Span>)>>,
509 /// When an error occurs, we want to avoid reporting "derived"
510 /// errors that are due to this original failure. Normally, we
511 /// handle this with the `err_count_on_creation` count, which
512 /// basically just tracks how many errors were reported when we
513 /// started type-checking a fn and checks to see if any new errors
514 /// have been reported since then. Not great, but it works.
516 /// However, when errors originated in other passes -- notably
517 /// resolve -- this heuristic breaks down. Therefore, we have this
518 /// auxiliary flag that one can set whenever one creates a
519 /// type-error that is due to an error in a prior pass.
521 /// Don't read this flag directly, call `is_tainted_by_errors()`
522 /// and `set_tainted_by_errors()`.
523 tainted_by_errors_flag: Cell<bool>,
525 /// Track how many errors were reported when this infcx is created.
526 /// If the number of errors increases, that's also a sign (line
527 /// `tained_by_errors`) to avoid reporting certain kinds of errors.
528 // FIXME(matthewjasper) Merge into `tainted_by_errors_flag`
529 err_count_on_creation: usize,
531 /// This flag is true while there is an active snapshot.
532 in_snapshot: Cell<bool>,
534 /// What is the innermost universe we have created? Starts out as
535 /// `UniverseIndex::root()` but grows from there as we enter
536 /// universal quantifiers.
538 /// N.B., at present, we exclude the universal quantifiers on the
539 /// item we are type-checking, and just consider those names as
540 /// part of the root universe. So this would only get incremented
541 /// when we enter into a higher-ranked (`for<..>`) type or trait
543 universe: Cell<ty::UniverseIndex>,
546 /// A map returned by `replace_bound_vars_with_placeholders()`
547 /// indicating the placeholder region that each late-bound region was
549 pub type PlaceholderMap<'tcx> = BTreeMap<ty::BoundRegion, ty::Region<'tcx>>;
551 /// See the `error_reporting` module for more details.
552 #[derive(Clone, Debug, PartialEq, Eq, TypeFoldable)]
553 pub enum ValuePairs<'tcx> {
554 Types(ExpectedFound<Ty<'tcx>>),
555 Regions(ExpectedFound<ty::Region<'tcx>>),
556 Consts(ExpectedFound<&'tcx ty::Const<'tcx>>),
557 TraitRefs(ExpectedFound<ty::TraitRef<'tcx>>),
558 PolyTraitRefs(ExpectedFound<ty::PolyTraitRef<'tcx>>),
561 /// The trace designates the path through inference that we took to
562 /// encounter an error or subtyping constraint.
564 /// See the `error_reporting` module for more details.
565 #[derive(Clone, Debug)]
566 pub struct TypeTrace<'tcx> {
567 cause: ObligationCause<'tcx>,
568 values: ValuePairs<'tcx>,
571 /// The origin of a `r1 <= r2` constraint.
573 /// See `error_reporting` module for more details
574 #[derive(Clone, Debug)]
575 pub enum SubregionOrigin<'tcx> {
576 /// Arose from a subtyping relation
577 Subtype(Box<TypeTrace<'tcx>>),
579 /// Stack-allocated closures cannot outlive innermost loop
580 /// or function so as to ensure we only require finite stack
581 InfStackClosure(Span),
583 /// Invocation of closure must be within its lifetime
586 /// Dereference of reference must be within its lifetime
589 /// Closure bound must not outlive captured variables
590 ClosureCapture(Span, hir::HirId),
592 /// Index into slice must be within its lifetime
595 /// When casting `&'a T` to an `&'b Trait` object,
596 /// relating `'a` to `'b`
597 RelateObjectBound(Span),
599 /// Some type parameter was instantiated with the given type,
600 /// and that type must outlive some region.
601 RelateParamBound(Span, Ty<'tcx>),
603 /// The given region parameter was instantiated with a region
604 /// that must outlive some other region.
605 RelateRegionParamBound(Span),
607 /// A bound placed on type parameters that states that must outlive
608 /// the moment of their instantiation.
609 RelateDefaultParamBound(Span, Ty<'tcx>),
611 /// Creating a pointer `b` to contents of another reference
614 /// Creating a pointer `b` to contents of an upvar
615 ReborrowUpvar(Span, ty::UpvarId),
617 /// Data with type `Ty<'tcx>` was borrowed
618 DataBorrowed(Ty<'tcx>, Span),
620 /// (&'a &'b T) where a >= b
621 ReferenceOutlivesReferent(Ty<'tcx>, Span),
623 /// Type or region parameters must be in scope.
624 ParameterInScope(ParameterOrigin, Span),
626 /// The type T of an expression E must outlive the lifetime for E.
627 ExprTypeIsNotInScope(Ty<'tcx>, Span),
629 /// A `ref b` whose region does not enclose the decl site
630 BindingTypeIsNotValidAtDecl(Span),
632 /// Regions appearing in a method receiver must outlive method call
635 /// Regions appearing in a function argument must outlive func call
638 /// Region in return type of invoked fn must enclose call
641 /// Operands must be in scope
644 /// Region resulting from a `&` expr must enclose the `&` expr
647 /// An auto-borrow that does not enclose the expr where it occurs
650 /// Region constraint arriving from destructor safety
651 SafeDestructor(Span),
653 /// Comparing the signature and requirements of an impl method against
654 /// the containing trait.
655 CompareImplMethodObligation {
657 item_name: ast::Name,
658 impl_item_def_id: DefId,
659 trait_item_def_id: DefId,
663 // `SubregionOrigin` is used a lot. Make sure it doesn't unintentionally get bigger.
664 #[cfg(target_arch = "x86_64")]
665 static_assert_size!(SubregionOrigin<'_>, 32);
667 /// Places that type/region parameters can appear.
668 #[derive(Clone, Copy, Debug)]
669 pub enum ParameterOrigin {
671 MethodCall, // foo.bar() <-- parameters on impl providing bar()
672 OverloadedOperator, // a + b when overloaded
673 OverloadedDeref, // *a when overloaded
676 /// Times when we replace late-bound regions with variables:
677 #[derive(Clone, Copy, Debug)]
678 pub enum LateBoundRegionConversionTime {
679 /// when a fn is called
682 /// when two higher-ranked types are compared
685 /// when projecting an associated type
686 AssocTypeProjection(DefId),
689 /// Reasons to create a region inference variable
691 /// See `error_reporting` module for more details
692 #[derive(Copy, Clone, Debug)]
693 pub enum RegionVariableOrigin {
694 /// Region variables created for ill-categorized reasons,
695 /// mostly indicates places in need of refactoring
698 /// Regions created by a `&P` or `[...]` pattern
701 /// Regions created by `&` operator
704 /// Regions created as part of an autoref of a method receiver
707 /// Regions created as part of an automatic coercion
710 /// Region variables created as the values for early-bound regions
711 EarlyBoundRegion(Span, Symbol),
713 /// Region variables created for bound regions
714 /// in a function or method that is called
715 LateBoundRegion(Span, ty::BoundRegion, LateBoundRegionConversionTime),
717 UpvarRegion(ty::UpvarId, Span),
719 BoundRegionInCoherence(ast::Name),
721 /// This origin is used for the inference variables that we create
722 /// during NLL region processing.
723 NLL(NLLRegionVariableOrigin),
726 #[derive(Copy, Clone, Debug)]
727 pub enum NLLRegionVariableOrigin {
728 /// During NLL region processing, we create variables for free
729 /// regions that we encounter in the function signature and
730 /// elsewhere. This origin indices we've got one of those.
733 /// "Universal" instantiation of a higher-ranked region (e.g.,
734 /// from a `for<'a> T` binder). Meant to represent "any region".
735 Placeholder(ty::PlaceholderRegion),
737 /// The variable we create to represent `'empty(U0)`.
741 /// If this is true, then this variable was created to represent a lifetime
742 /// bound in a `for` binder. For example, it might have been created to
743 /// represent the lifetime `'a` in a type like `for<'a> fn(&'a u32)`.
744 /// Such variables are created when we are trying to figure out if there
745 /// is any valid instantiation of `'a` that could fit into some scenario.
747 /// This is used to inform error reporting: in the case that we are trying to
748 /// determine whether there is any valid instantiation of a `'a` variable that meets
749 /// some constraint C, we want to blame the "source" of that `for` type,
750 /// rather than blaming the source of the constraint C.
755 impl NLLRegionVariableOrigin {
756 pub fn is_universal(self) -> bool {
758 NLLRegionVariableOrigin::FreeRegion => true,
759 NLLRegionVariableOrigin::Placeholder(..) => true,
760 NLLRegionVariableOrigin::Existential { .. } => false,
761 NLLRegionVariableOrigin::RootEmptyRegion => false,
765 pub fn is_existential(self) -> bool {
770 // FIXME(eddyb) investigate overlap between this and `TyOrConstInferVar`.
771 #[derive(Copy, Clone, Debug)]
772 pub enum FixupError<'tcx> {
773 UnresolvedIntTy(IntVid),
774 UnresolvedFloatTy(FloatVid),
776 UnresolvedConst(ConstVid<'tcx>),
779 /// See the `region_obligations` field for more information.
781 pub struct RegionObligation<'tcx> {
782 pub sub_region: ty::Region<'tcx>,
783 pub sup_type: Ty<'tcx>,
784 pub origin: SubregionOrigin<'tcx>,
787 impl<'tcx> fmt::Display for FixupError<'tcx> {
788 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
789 use self::FixupError::*;
792 UnresolvedIntTy(_) => write!(
794 "cannot determine the type of this integer; \
795 add a suffix to specify the type explicitly"
797 UnresolvedFloatTy(_) => write!(
799 "cannot determine the type of this number; \
800 add a suffix to specify the type explicitly"
802 UnresolvedTy(_) => write!(f, "unconstrained type"),
803 UnresolvedConst(_) => write!(f, "unconstrained const value"),
808 /// Helper type of a temporary returned by `tcx.infer_ctxt()`.
809 /// Necessary because we can't write the following bound:
810 /// `F: for<'b, 'tcx> where 'tcx FnOnce(InferCtxt<'b, 'tcx>)`.
811 pub struct InferCtxtBuilder<'tcx> {
812 global_tcx: TyCtxt<'tcx>,
813 fresh_tables: Option<RefCell<ty::TypeckTables<'tcx>>>,
816 pub trait TyCtxtInferExt<'tcx> {
817 fn infer_ctxt(self) -> InferCtxtBuilder<'tcx>;
820 impl TyCtxtInferExt<'tcx> for TyCtxt<'tcx> {
821 fn infer_ctxt(self) -> InferCtxtBuilder<'tcx> {
822 InferCtxtBuilder { global_tcx: self, fresh_tables: None }
826 impl<'tcx> InferCtxtBuilder<'tcx> {
827 /// Used only by `rustc_typeck` during body type-checking/inference,
828 /// will initialize `in_progress_tables` with fresh `TypeckTables`.
829 pub fn with_fresh_in_progress_tables(mut self, table_owner: LocalDefId) -> Self {
830 self.fresh_tables = Some(RefCell::new(ty::TypeckTables::empty(Some(table_owner))));
834 /// Given a canonical value `C` as a starting point, create an
835 /// inference context that contains each of the bound values
836 /// within instantiated as a fresh variable. The `f` closure is
837 /// invoked with the new infcx, along with the instantiated value
838 /// `V` and a substitution `S`. This substitution `S` maps from
839 /// the bound values in `C` to their instantiated values in `V`
840 /// (in other words, `S(C) = V`).
841 pub fn enter_with_canonical<T, R>(
844 canonical: &Canonical<'tcx, T>,
845 f: impl for<'a> FnOnce(InferCtxt<'a, 'tcx>, T, CanonicalVarValues<'tcx>) -> R,
848 T: TypeFoldable<'tcx>,
852 infcx.instantiate_canonical_with_fresh_inference_vars(span, canonical);
853 f(infcx, value, subst)
857 pub fn enter<R>(&mut self, f: impl for<'a> FnOnce(InferCtxt<'a, 'tcx>) -> R) -> R {
858 let InferCtxtBuilder { global_tcx, ref fresh_tables } = *self;
859 let in_progress_tables = fresh_tables.as_ref();
860 global_tcx.enter_local(|tcx| {
864 inner: RefCell::new(InferCtxtInner::new()),
865 lexical_region_resolutions: RefCell::new(None),
866 selection_cache: Default::default(),
867 evaluation_cache: Default::default(),
868 reported_trait_errors: Default::default(),
869 reported_closure_mismatch: Default::default(),
870 tainted_by_errors_flag: Cell::new(false),
871 err_count_on_creation: tcx.sess.err_count(),
872 in_snapshot: Cell::new(false),
873 skip_leak_check: Cell::new(false),
874 universe: Cell::new(ty::UniverseIndex::ROOT),
880 impl<'tcx, T> InferOk<'tcx, T> {
881 pub fn unit(self) -> InferOk<'tcx, ()> {
882 InferOk { value: (), obligations: self.obligations }
885 /// Extracts `value`, registering any obligations into `fulfill_cx`.
886 pub fn into_value_registering_obligations(
888 infcx: &InferCtxt<'_, 'tcx>,
889 fulfill_cx: &mut dyn TraitEngine<'tcx>,
891 let InferOk { value, obligations } = self;
892 for obligation in obligations {
893 fulfill_cx.register_predicate_obligation(infcx, obligation);
899 impl<'tcx> InferOk<'tcx, ()> {
900 pub fn into_obligations(self) -> PredicateObligations<'tcx> {
905 #[must_use = "once you start a snapshot, you should always consume it"]
906 pub struct FullSnapshot<'a, 'tcx> {
907 snapshot: CombinedSnapshot<'a, 'tcx>,
908 region_constraints_snapshot: RegionSnapshot,
909 type_snapshot: type_variable::Snapshot<'tcx>,
910 const_snapshot: usize,
912 float_snapshot: usize,
915 #[must_use = "once you start a snapshot, you should always consume it"]
916 pub struct CombinedSnapshot<'a, 'tcx> {
917 undo_snapshot: Snapshot<'tcx>,
918 region_obligations_snapshot: usize,
919 universe: ty::UniverseIndex,
920 was_in_snapshot: bool,
921 was_skip_leak_check: bool,
922 _in_progress_tables: Option<Ref<'a, ty::TypeckTables<'tcx>>>,
925 impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
926 pub fn is_in_snapshot(&self) -> bool {
927 self.in_snapshot.get()
930 pub fn freshen<T: TypeFoldable<'tcx>>(&self, t: T) -> T {
931 t.fold_with(&mut self.freshener())
934 pub fn type_var_diverges(&'a self, ty: Ty<'_>) -> bool {
936 ty::Infer(ty::TyVar(vid)) => self.inner.borrow_mut().type_variables().var_diverges(vid),
941 pub fn freshener<'b>(&'b self) -> TypeFreshener<'b, 'tcx> {
942 freshen::TypeFreshener::new(self)
945 pub fn type_is_unconstrained_numeric(&'a self, ty: Ty<'_>) -> UnconstrainedNumeric {
946 use rustc_middle::ty::error::UnconstrainedNumeric::Neither;
947 use rustc_middle::ty::error::UnconstrainedNumeric::{UnconstrainedFloat, UnconstrainedInt};
949 ty::Infer(ty::IntVar(vid)) => {
950 if self.inner.borrow_mut().int_unification_table().probe_value(vid).is_some() {
956 ty::Infer(ty::FloatVar(vid)) => {
957 if self.inner.borrow_mut().float_unification_table().probe_value(vid).is_some() {
967 pub fn unsolved_variables(&self) -> Vec<Ty<'tcx>> {
968 let mut inner = self.inner.borrow_mut();
969 // FIXME(const_generics): should there be an equivalent function for const variables?
971 let mut vars: Vec<Ty<'_>> = inner
973 .unsolved_variables()
975 .map(|t| self.tcx.mk_ty_var(t))
978 (0..inner.int_unification_table().len())
979 .map(|i| ty::IntVid { index: i as u32 })
980 .filter(|&vid| inner.int_unification_table().probe_value(vid).is_none())
981 .map(|v| self.tcx.mk_int_var(v)),
984 (0..inner.float_unification_table().len())
985 .map(|i| ty::FloatVid { index: i as u32 })
986 .filter(|&vid| inner.float_unification_table().probe_value(vid).is_none())
987 .map(|v| self.tcx.mk_float_var(v)),
994 trace: TypeTrace<'tcx>,
995 param_env: ty::ParamEnv<'tcx>,
996 ) -> CombineFields<'a, 'tcx> {
1002 obligations: PredicateObligations::new(),
1006 /// Clear the "currently in a snapshot" flag, invoke the closure,
1007 /// then restore the flag to its original value. This flag is a
1008 /// debugging measure designed to detect cases where we start a
1009 /// snapshot, create type variables, and register obligations
1010 /// which may involve those type variables in the fulfillment cx,
1011 /// potentially leaving "dangling type variables" behind.
1012 /// In such cases, an assertion will fail when attempting to
1013 /// register obligations, within a snapshot. Very useful, much
1014 /// better than grovelling through megabytes of `RUSTC_LOG` output.
1016 /// HOWEVER, in some cases the flag is unhelpful. In particular, we
1017 /// sometimes create a "mini-fulfilment-cx" in which we enroll
1018 /// obligations. As long as this fulfillment cx is fully drained
1019 /// before we return, this is not a problem, as there won't be any
1020 /// escaping obligations in the main cx. In those cases, you can
1021 /// use this function.
1022 pub fn save_and_restore_in_snapshot_flag<F, R>(&self, func: F) -> R
1024 F: FnOnce(&Self) -> R,
1026 let flag = self.in_snapshot.replace(false);
1027 let result = func(self);
1028 self.in_snapshot.set(flag);
1032 fn start_full_snapshot(&self) -> FullSnapshot<'a, 'tcx> {
1033 let snapshot = self.start_snapshot();
1034 let mut inner = self.inner.borrow_mut();
1037 type_snapshot: inner.type_variables().snapshot(),
1038 const_snapshot: inner.const_unification_table().len(),
1039 int_snapshot: inner.int_unification_table().len(),
1040 float_snapshot: inner.float_unification_table().len(),
1041 region_constraints_snapshot: inner.unwrap_region_constraints().start_snapshot(),
1045 fn start_snapshot(&self) -> CombinedSnapshot<'a, 'tcx> {
1046 debug!("start_snapshot()");
1048 let in_snapshot = self.in_snapshot.replace(true);
1050 let mut inner = self.inner.borrow_mut();
1052 inner.undo_log.num_open_snapshots += 1;
1053 let undo_snapshot = Snapshot { undo_len: inner.undo_log.logs.len(), _marker: PhantomData };
1056 region_obligations_snapshot: inner.region_obligations.len(),
1057 universe: self.universe(),
1058 was_in_snapshot: in_snapshot,
1059 was_skip_leak_check: self.skip_leak_check.get(),
1060 // Borrow tables "in progress" (i.e., during typeck)
1061 // to ban writes from within a snapshot to them.
1062 _in_progress_tables: self.in_progress_tables.map(|tables| tables.borrow()),
1066 fn rollback_to(&self, cause: &str, snapshot: CombinedSnapshot<'a, 'tcx>) {
1067 debug!("rollback_to(cause={})", cause);
1068 let CombinedSnapshot {
1070 region_obligations_snapshot,
1073 was_skip_leak_check,
1074 _in_progress_tables,
1077 self.in_snapshot.set(was_in_snapshot);
1078 self.universe.set(universe);
1079 self.skip_leak_check.set(was_skip_leak_check);
1081 let InferCtxtInner {
1083 const_unification_table,
1084 int_unification_table,
1085 float_unification_table,
1091 } = &mut *self.inner.borrow_mut();
1092 undo_log.rollback_to(
1094 type_variables: type_variable::RollbackView::from(type_variables),
1095 const_unification_table,
1096 int_unification_table,
1097 float_unification_table,
1098 region_constraints: region_constraints.as_mut().unwrap(),
1103 region_obligations.truncate(region_obligations_snapshot);
1106 fn commit_from(&self, snapshot: CombinedSnapshot<'a, 'tcx>) {
1107 debug!("commit_from()");
1108 let CombinedSnapshot {
1110 region_obligations_snapshot: _,
1113 was_skip_leak_check,
1114 _in_progress_tables,
1117 self.in_snapshot.set(was_in_snapshot);
1118 self.skip_leak_check.set(was_skip_leak_check);
1120 let mut inner = self.inner.borrow_mut();
1121 inner.undo_log.commit(undo_snapshot);
1124 /// Executes `f` and commit the bindings.
1125 pub fn commit_unconditionally<R, F>(&self, f: F) -> R
1127 F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> R,
1129 debug!("commit_unconditionally()");
1130 let snapshot = self.start_snapshot();
1131 let r = f(&snapshot);
1132 self.commit_from(snapshot);
1136 /// Execute `f` and commit the bindings if closure `f` returns `Ok(_)`.
1137 pub fn commit_if_ok<T, E, F>(&self, f: F) -> Result<T, E>
1139 F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> Result<T, E>,
1141 debug!("commit_if_ok()");
1142 let snapshot = self.start_snapshot();
1143 let r = f(&snapshot);
1144 debug!("commit_if_ok() -- r.is_ok() = {}", r.is_ok());
1147 self.commit_from(snapshot);
1150 self.rollback_to("commit_if_ok -- error", snapshot);
1156 /// Execute `f` then unroll any bindings it creates.
1157 pub fn probe<R, F>(&self, f: F) -> R
1159 F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> R,
1162 let snapshot = self.start_snapshot();
1163 let r = f(&snapshot);
1164 self.rollback_to("probe", snapshot);
1168 pub fn probe_full<R, F>(&self, f: F) -> R
1170 F: FnOnce(&FullSnapshot<'a, 'tcx>) -> R,
1173 let snapshot = self.start_full_snapshot();
1174 let r = f(&snapshot);
1175 self.rollback_to("probe", snapshot.snapshot);
1179 /// If `should_skip` is true, then execute `f` then unroll any bindings it creates.
1180 pub fn probe_maybe_skip_leak_check<R, F>(&self, should_skip: bool, f: F) -> R
1182 F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> R,
1185 let snapshot = self.start_snapshot();
1186 let skip_leak_check = should_skip || self.skip_leak_check.get();
1187 self.skip_leak_check.set(skip_leak_check);
1188 let r = f(&snapshot);
1189 self.rollback_to("probe", snapshot);
1193 /// Scan the constraints produced since `snapshot` began and returns:
1195 /// - `None` -- if none of them involve "region outlives" constraints
1196 /// - `Some(true)` -- if there are `'a: 'b` constraints where `'a` or `'b` is a placeholder
1197 /// - `Some(false)` -- if there are `'a: 'b` constraints but none involve placeholders
1198 pub fn region_constraints_added_in_snapshot(
1200 snapshot: &CombinedSnapshot<'a, 'tcx>,
1204 .unwrap_region_constraints()
1205 .region_constraints_added_in_snapshot(&snapshot.undo_snapshot)
1208 pub fn add_given(&self, sub: ty::Region<'tcx>, sup: ty::RegionVid) {
1209 self.inner.borrow_mut().unwrap_region_constraints().add_given(sub, sup);
1212 pub fn can_sub<T>(&self, param_env: ty::ParamEnv<'tcx>, a: T, b: T) -> UnitResult<'tcx>
1214 T: at::ToTrace<'tcx>,
1216 let origin = &ObligationCause::dummy();
1218 self.at(origin, param_env).sub(a, b).map(|InferOk { obligations: _, .. }| {
1219 // Ignore obligations, since we are unrolling
1220 // everything anyway.
1225 pub fn can_eq<T>(&self, param_env: ty::ParamEnv<'tcx>, a: T, b: T) -> UnitResult<'tcx>
1227 T: at::ToTrace<'tcx>,
1229 let origin = &ObligationCause::dummy();
1231 self.at(origin, param_env).eq(a, b).map(|InferOk { obligations: _, .. }| {
1232 // Ignore obligations, since we are unrolling
1233 // everything anyway.
1240 origin: SubregionOrigin<'tcx>,
1241 a: ty::Region<'tcx>,
1242 b: ty::Region<'tcx>,
1244 debug!("sub_regions({:?} <: {:?})", a, b);
1245 self.inner.borrow_mut().unwrap_region_constraints().make_subregion(origin, a, b);
1248 /// Require that the region `r` be equal to one of the regions in
1249 /// the set `regions`.
1250 pub fn member_constraint(
1252 opaque_type_def_id: DefId,
1253 definition_span: Span,
1254 hidden_ty: Ty<'tcx>,
1255 region: ty::Region<'tcx>,
1256 in_regions: &Lrc<Vec<ty::Region<'tcx>>>,
1258 debug!("member_constraint({:?} <: {:?})", region, in_regions);
1259 self.inner.borrow_mut().unwrap_region_constraints().member_constraint(
1268 pub fn subtype_predicate(
1270 cause: &ObligationCause<'tcx>,
1271 param_env: ty::ParamEnv<'tcx>,
1272 predicate: &ty::PolySubtypePredicate<'tcx>,
1273 ) -> Option<InferResult<'tcx, ()>> {
1274 // Subtle: it's ok to skip the binder here and resolve because
1275 // `shallow_resolve` just ignores anything that is not a type
1276 // variable, and because type variable's can't (at present, at
1277 // least) capture any of the things bound by this binder.
1279 // NOTE(nmatsakis): really, there is no *particular* reason to do this
1280 // `shallow_resolve` here except as a micro-optimization.
1281 // Naturally I could not resist.
1282 let two_unbound_type_vars = {
1283 let a = self.shallow_resolve(predicate.skip_binder().a);
1284 let b = self.shallow_resolve(predicate.skip_binder().b);
1285 a.is_ty_var() && b.is_ty_var()
1288 if two_unbound_type_vars {
1289 // Two unbound type variables? Can't make progress.
1293 Some(self.commit_if_ok(|snapshot| {
1294 let (ty::SubtypePredicate { a_is_expected, a, b }, placeholder_map) =
1295 self.replace_bound_vars_with_placeholders(predicate);
1297 let ok = self.at(cause, param_env).sub_exp(a_is_expected, a, b)?;
1299 self.leak_check(false, &placeholder_map, snapshot)?;
1305 pub fn region_outlives_predicate(
1307 cause: &traits::ObligationCause<'tcx>,
1308 predicate: &ty::PolyRegionOutlivesPredicate<'tcx>,
1309 ) -> UnitResult<'tcx> {
1310 self.commit_if_ok(|snapshot| {
1311 let (ty::OutlivesPredicate(r_a, r_b), placeholder_map) =
1312 self.replace_bound_vars_with_placeholders(predicate);
1313 let origin = SubregionOrigin::from_obligation_cause(cause, || {
1314 RelateRegionParamBound(cause.span)
1316 self.sub_regions(origin, r_b, r_a); // `b : a` ==> `a <= b`
1317 self.leak_check(false, &placeholder_map, snapshot)?;
1322 pub fn next_ty_var_id(&self, diverging: bool, origin: TypeVariableOrigin) -> TyVid {
1323 self.inner.borrow_mut().type_variables().new_var(self.universe(), diverging, origin)
1326 pub fn next_ty_var(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
1327 self.tcx.mk_ty_var(self.next_ty_var_id(false, origin))
1330 pub fn next_ty_var_in_universe(
1332 origin: TypeVariableOrigin,
1333 universe: ty::UniverseIndex,
1335 let vid = self.inner.borrow_mut().type_variables().new_var(universe, false, origin);
1336 self.tcx.mk_ty_var(vid)
1339 pub fn next_diverging_ty_var(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
1340 self.tcx.mk_ty_var(self.next_ty_var_id(true, origin))
1343 pub fn next_const_var(
1346 origin: ConstVariableOrigin,
1347 ) -> &'tcx ty::Const<'tcx> {
1348 self.tcx.mk_const_var(self.next_const_var_id(origin), ty)
1351 pub fn next_const_var_in_universe(
1354 origin: ConstVariableOrigin,
1355 universe: ty::UniverseIndex,
1356 ) -> &'tcx ty::Const<'tcx> {
1360 .const_unification_table()
1361 .new_key(ConstVarValue { origin, val: ConstVariableValue::Unknown { universe } });
1362 self.tcx.mk_const_var(vid, ty)
1365 pub fn next_const_var_id(&self, origin: ConstVariableOrigin) -> ConstVid<'tcx> {
1366 self.inner.borrow_mut().const_unification_table().new_key(ConstVarValue {
1368 val: ConstVariableValue::Unknown { universe: self.universe() },
1372 fn next_int_var_id(&self) -> IntVid {
1373 self.inner.borrow_mut().int_unification_table().new_key(None)
1376 pub fn next_int_var(&self) -> Ty<'tcx> {
1377 self.tcx.mk_int_var(self.next_int_var_id())
1380 fn next_float_var_id(&self) -> FloatVid {
1381 self.inner.borrow_mut().float_unification_table().new_key(None)
1384 pub fn next_float_var(&self) -> Ty<'tcx> {
1385 self.tcx.mk_float_var(self.next_float_var_id())
1388 /// Creates a fresh region variable with the next available index.
1389 /// The variable will be created in the maximum universe created
1390 /// thus far, allowing it to name any region created thus far.
1391 pub fn next_region_var(&self, origin: RegionVariableOrigin) -> ty::Region<'tcx> {
1392 self.next_region_var_in_universe(origin, self.universe())
1395 /// Creates a fresh region variable with the next available index
1396 /// in the given universe; typically, you can use
1397 /// `next_region_var` and just use the maximal universe.
1398 pub fn next_region_var_in_universe(
1400 origin: RegionVariableOrigin,
1401 universe: ty::UniverseIndex,
1402 ) -> ty::Region<'tcx> {
1404 self.inner.borrow_mut().unwrap_region_constraints().new_region_var(universe, origin);
1405 self.tcx.mk_region(ty::ReVar(region_var))
1408 /// Return the universe that the region `r` was created in. For
1409 /// most regions (e.g., `'static`, named regions from the user,
1410 /// etc) this is the root universe U0. For inference variables or
1411 /// placeholders, however, it will return the universe which which
1412 /// they are associated.
1413 fn universe_of_region(&self, r: ty::Region<'tcx>) -> ty::UniverseIndex {
1414 self.inner.borrow_mut().unwrap_region_constraints().universe(r)
1417 /// Number of region variables created so far.
1418 pub fn num_region_vars(&self) -> usize {
1419 self.inner.borrow_mut().unwrap_region_constraints().num_region_vars()
1422 /// Just a convenient wrapper of `next_region_var` for using during NLL.
1423 pub fn next_nll_region_var(&self, origin: NLLRegionVariableOrigin) -> ty::Region<'tcx> {
1424 self.next_region_var(RegionVariableOrigin::NLL(origin))
1427 /// Just a convenient wrapper of `next_region_var` for using during NLL.
1428 pub fn next_nll_region_var_in_universe(
1430 origin: NLLRegionVariableOrigin,
1431 universe: ty::UniverseIndex,
1432 ) -> ty::Region<'tcx> {
1433 self.next_region_var_in_universe(RegionVariableOrigin::NLL(origin), universe)
1436 pub fn var_for_def(&self, span: Span, param: &ty::GenericParamDef) -> GenericArg<'tcx> {
1438 GenericParamDefKind::Lifetime => {
1439 // Create a region inference variable for the given
1440 // region parameter definition.
1441 self.next_region_var(EarlyBoundRegion(span, param.name)).into()
1443 GenericParamDefKind::Type { .. } => {
1444 // Create a type inference variable for the given
1445 // type parameter definition. The substitutions are
1446 // for actual parameters that may be referred to by
1447 // the default of this type parameter, if it exists.
1448 // e.g., `struct Foo<A, B, C = (A, B)>(...);` when
1449 // used in a path such as `Foo::<T, U>::new()` will
1450 // use an inference variable for `C` with `[T, U]`
1451 // as the substitutions for the default, `(T, U)`.
1452 let ty_var_id = self.inner.borrow_mut().type_variables().new_var(
1455 TypeVariableOrigin {
1456 kind: TypeVariableOriginKind::TypeParameterDefinition(
1464 self.tcx.mk_ty_var(ty_var_id).into()
1466 GenericParamDefKind::Const { .. } => {
1467 let origin = ConstVariableOrigin {
1468 kind: ConstVariableOriginKind::ConstParameterDefinition(param.name),
1472 self.inner.borrow_mut().const_unification_table().new_key(ConstVarValue {
1474 val: ConstVariableValue::Unknown { universe: self.universe() },
1476 self.tcx.mk_const_var(const_var_id, self.tcx.type_of(param.def_id)).into()
1481 /// Given a set of generics defined on a type or impl, returns a substitution mapping each
1482 /// type/region parameter to a fresh inference variable.
1483 pub fn fresh_substs_for_item(&self, span: Span, def_id: DefId) -> SubstsRef<'tcx> {
1484 InternalSubsts::for_item(self.tcx, def_id, |param, _| self.var_for_def(span, param))
1487 /// Returns `true` if errors have been reported since this infcx was
1488 /// created. This is sometimes used as a heuristic to skip
1489 /// reporting errors that often occur as a result of earlier
1490 /// errors, but where it's hard to be 100% sure (e.g., unresolved
1491 /// inference variables, regionck errors).
1492 pub fn is_tainted_by_errors(&self) -> bool {
1494 "is_tainted_by_errors(err_count={}, err_count_on_creation={}, \
1495 tainted_by_errors_flag={})",
1496 self.tcx.sess.err_count(),
1497 self.err_count_on_creation,
1498 self.tainted_by_errors_flag.get()
1501 if self.tcx.sess.err_count() > self.err_count_on_creation {
1502 return true; // errors reported since this infcx was made
1504 self.tainted_by_errors_flag.get()
1507 /// Set the "tainted by errors" flag to true. We call this when we
1508 /// observe an error from a prior pass.
1509 pub fn set_tainted_by_errors(&self) {
1510 debug!("set_tainted_by_errors()");
1511 self.tainted_by_errors_flag.set(true)
1514 /// Process the region constraints and report any errors that
1515 /// result. After this, no more unification operations should be
1516 /// done -- or the compiler will panic -- but it is legal to use
1517 /// `resolve_vars_if_possible` as well as `fully_resolve`.
1518 pub fn resolve_regions_and_report_errors(
1520 region_context: DefId,
1521 region_map: ®ion::ScopeTree,
1522 outlives_env: &OutlivesEnvironment<'tcx>,
1526 self.is_tainted_by_errors() || self.inner.borrow().region_obligations.is_empty(),
1527 "region_obligations not empty: {:#?}",
1528 self.inner.borrow().region_obligations
1530 let (var_infos, data) = self
1535 .expect("regions already resolved")
1536 .with_log(&mut inner.undo_log)
1537 .into_infos_and_data();
1539 let region_rels = &RegionRelations::new(
1543 outlives_env.free_region_map(),
1546 let (lexical_region_resolutions, errors) =
1547 lexical_region_resolve::resolve(region_rels, var_infos, data, mode);
1549 let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
1550 assert!(old_value.is_none());
1552 if !self.is_tainted_by_errors() {
1553 // As a heuristic, just skip reporting region errors
1554 // altogether if other errors have been reported while
1555 // this infcx was in use. This is totally hokey but
1556 // otherwise we have a hard time separating legit region
1557 // errors from silly ones.
1558 self.report_region_errors(region_map, &errors);
1562 /// Obtains (and clears) the current set of region
1563 /// constraints. The inference context is still usable: further
1564 /// unifications will simply add new constraints.
1566 /// This method is not meant to be used with normal lexical region
1567 /// resolution. Rather, it is used in the NLL mode as a kind of
1568 /// interim hack: basically we run normal type-check and generate
1569 /// region constraints as normal, but then we take them and
1570 /// translate them into the form that the NLL solver
1571 /// understands. See the NLL module for mode details.
1572 pub fn take_and_reset_region_constraints(&self) -> RegionConstraintData<'tcx> {
1574 self.inner.borrow().region_obligations.is_empty(),
1575 "region_obligations not empty: {:#?}",
1576 self.inner.borrow().region_obligations
1579 self.inner.borrow_mut().unwrap_region_constraints().take_and_reset_data()
1582 /// Gives temporary access to the region constraint data.
1583 #[allow(non_camel_case_types)] // bug with impl trait
1584 pub fn with_region_constraints<R>(
1586 op: impl FnOnce(&RegionConstraintData<'tcx>) -> R,
1588 let mut inner = self.inner.borrow_mut();
1589 op(inner.unwrap_region_constraints().data())
1592 /// Takes ownership of the list of variable regions. This implies
1593 /// that all the region constraints have already been taken, and
1594 /// hence that `resolve_regions_and_report_errors` can never be
1595 /// called. This is used only during NLL processing to "hand off" ownership
1596 /// of the set of region variables into the NLL region context.
1597 pub fn take_region_var_origins(&self) -> VarInfos {
1598 let mut inner = self.inner.borrow_mut();
1599 let (var_infos, data) = inner
1602 .expect("regions already resolved")
1603 .with_log(&mut inner.undo_log)
1604 .into_infos_and_data();
1605 assert!(data.is_empty());
1609 pub fn ty_to_string(&self, t: Ty<'tcx>) -> String {
1610 self.resolve_vars_if_possible(&t).to_string()
1613 pub fn tys_to_string(&self, ts: &[Ty<'tcx>]) -> String {
1614 let tstrs: Vec<String> = ts.iter().map(|t| self.ty_to_string(*t)).collect();
1615 format!("({})", tstrs.join(", "))
1618 pub fn trait_ref_to_string(&self, t: &ty::TraitRef<'tcx>) -> String {
1619 self.resolve_vars_if_possible(t).print_only_trait_path().to_string()
1622 /// If `TyVar(vid)` resolves to a type, return that type. Else, return the
1623 /// universe index of `TyVar(vid)`.
1624 pub fn probe_ty_var(&self, vid: TyVid) -> Result<Ty<'tcx>, ty::UniverseIndex> {
1625 use self::type_variable::TypeVariableValue;
1627 match self.inner.borrow_mut().type_variables().probe(vid) {
1628 TypeVariableValue::Known { value } => Ok(value),
1629 TypeVariableValue::Unknown { universe } => Err(universe),
1633 /// Resolve any type variables found in `value` -- but only one
1634 /// level. So, if the variable `?X` is bound to some type
1635 /// `Foo<?Y>`, then this would return `Foo<?Y>` (but `?Y` may
1636 /// itself be bound to a type).
1638 /// Useful when you only need to inspect the outermost level of
1639 /// the type and don't care about nested types (or perhaps you
1640 /// will be resolving them as well, e.g. in a loop).
1641 pub fn shallow_resolve<T>(&self, value: T) -> T
1643 T: TypeFoldable<'tcx>,
1645 value.fold_with(&mut ShallowResolver { infcx: self })
1648 pub fn root_var(&self, var: ty::TyVid) -> ty::TyVid {
1649 self.inner.borrow_mut().type_variables().root_var(var)
1652 /// Where possible, replaces type/const variables in
1653 /// `value` with their final value. Note that region variables
1654 /// are unaffected. If a type/const variable has not been unified, it
1655 /// is left as is. This is an idempotent operation that does
1656 /// not affect inference state in any way and so you can do it
1658 pub fn resolve_vars_if_possible<T>(&self, value: &T) -> T
1660 T: TypeFoldable<'tcx>,
1662 if !value.needs_infer() {
1663 return value.clone(); // Avoid duplicated subst-folding.
1665 let mut r = resolve::OpportunisticVarResolver::new(self);
1666 value.fold_with(&mut r)
1669 /// Returns the first unresolved variable contained in `T`. In the
1670 /// process of visiting `T`, this will resolve (where possible)
1671 /// type variables in `T`, but it never constructs the final,
1672 /// resolved type, so it's more efficient than
1673 /// `resolve_vars_if_possible()`.
1674 pub fn unresolved_type_vars<T>(&self, value: &T) -> Option<(Ty<'tcx>, Option<Span>)>
1676 T: TypeFoldable<'tcx>,
1678 let mut r = resolve::UnresolvedTypeFinder::new(self);
1679 value.visit_with(&mut r);
1683 pub fn probe_const_var(
1685 vid: ty::ConstVid<'tcx>,
1686 ) -> Result<&'tcx ty::Const<'tcx>, ty::UniverseIndex> {
1687 match self.inner.borrow_mut().const_unification_table().probe_value(vid).val {
1688 ConstVariableValue::Known { value } => Ok(value),
1689 ConstVariableValue::Unknown { universe } => Err(universe),
1693 pub fn fully_resolve<T: TypeFoldable<'tcx>>(&self, value: &T) -> FixupResult<'tcx, T> {
1695 * Attempts to resolve all type/region/const variables in
1696 * `value`. Region inference must have been run already (e.g.,
1697 * by calling `resolve_regions_and_report_errors`). If some
1698 * variable was never unified, an `Err` results.
1700 * This method is idempotent, but it not typically not invoked
1701 * except during the writeback phase.
1704 resolve::fully_resolve(self, value)
1707 // [Note-Type-error-reporting]
1708 // An invariant is that anytime the expected or actual type is Error (the special
1709 // error type, meaning that an error occurred when typechecking this expression),
1710 // this is a derived error. The error cascaded from another error (that was already
1711 // reported), so it's not useful to display it to the user.
1712 // The following methods implement this logic.
1713 // They check if either the actual or expected type is Error, and don't print the error
1714 // in this case. The typechecker should only ever report type errors involving mismatched
1715 // types using one of these methods, and should not call span_err directly for such
1718 pub fn type_error_struct_with_diag<M>(
1722 actual_ty: Ty<'tcx>,
1723 ) -> DiagnosticBuilder<'tcx>
1725 M: FnOnce(String) -> DiagnosticBuilder<'tcx>,
1727 let actual_ty = self.resolve_vars_if_possible(&actual_ty);
1728 debug!("type_error_struct_with_diag({:?}, {:?})", sp, actual_ty);
1730 // Don't report an error if actual type is `Error`.
1731 if actual_ty.references_error() {
1732 return self.tcx.sess.diagnostic().struct_dummy();
1735 mk_diag(self.ty_to_string(actual_ty))
1738 pub fn report_mismatched_types(
1740 cause: &ObligationCause<'tcx>,
1743 err: TypeError<'tcx>,
1744 ) -> DiagnosticBuilder<'tcx> {
1745 let trace = TypeTrace::types(cause, true, expected, actual);
1746 self.report_and_explain_type_error(trace, &err)
1749 pub fn replace_bound_vars_with_fresh_vars<T>(
1752 lbrct: LateBoundRegionConversionTime,
1753 value: &ty::Binder<T>,
1754 ) -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
1756 T: TypeFoldable<'tcx>,
1758 let fld_r = |br| self.next_region_var(LateBoundRegion(span, br, lbrct));
1760 self.next_ty_var(TypeVariableOrigin {
1761 kind: TypeVariableOriginKind::MiscVariable,
1765 let fld_c = |_, ty| {
1766 self.next_const_var(
1768 ConstVariableOrigin { kind: ConstVariableOriginKind::MiscVariable, span },
1771 self.tcx.replace_bound_vars(value, fld_r, fld_t, fld_c)
1774 /// See the [`region_constraints::RegionConstraintCollector::verify_generic_bound`] method.
1775 pub fn verify_generic_bound(
1777 origin: SubregionOrigin<'tcx>,
1778 kind: GenericKind<'tcx>,
1779 a: ty::Region<'tcx>,
1780 bound: VerifyBound<'tcx>,
1782 debug!("verify_generic_bound({:?}, {:?} <: {:?})", kind, a, bound);
1786 .unwrap_region_constraints()
1787 .verify_generic_bound(origin, kind, a, bound);
1790 /// Obtains the latest type of the given closure; this may be a
1791 /// closure in the current function, in which case its
1792 /// `ClosureKind` may not yet be known.
1793 pub fn closure_kind(&self, closure_substs: SubstsRef<'tcx>) -> Option<ty::ClosureKind> {
1794 let closure_kind_ty = closure_substs.as_closure().kind_ty();
1795 let closure_kind_ty = self.shallow_resolve(closure_kind_ty);
1796 closure_kind_ty.to_opt_closure_kind()
1799 /// Clears the selection, evaluation, and projection caches. This is useful when
1800 /// repeatedly attempting to select an `Obligation` while changing only
1801 /// its `ParamEnv`, since `FulfillmentContext` doesn't use probing.
1802 pub fn clear_caches(&self) {
1803 self.selection_cache.clear();
1804 self.evaluation_cache.clear();
1805 self.inner.borrow_mut().projection_cache().clear();
1808 fn universe(&self) -> ty::UniverseIndex {
1812 /// Creates and return a fresh universe that extends all previous
1813 /// universes. Updates `self.universe` to that new universe.
1814 pub fn create_next_universe(&self) -> ty::UniverseIndex {
1815 let u = self.universe.get().next_universe();
1816 self.universe.set(u);
1820 /// Resolves and evaluates a constant.
1822 /// The constant can be located on a trait like `<A as B>::C`, in which case the given
1823 /// substitutions and environment are used to resolve the constant. Alternatively if the
1824 /// constant has generic parameters in scope the substitutions are used to evaluate the value of
1825 /// the constant. For example in `fn foo<T>() { let _ = [0; bar::<T>()]; }` the repeat count
1826 /// constant `bar::<T>()` requires a substitution for `T`, if the substitution for `T` is still
1827 /// too generic for the constant to be evaluated then `Err(ErrorHandled::TooGeneric)` is
1830 /// This handles inferences variables within both `param_env` and `substs` by
1831 /// performing the operation on their respective canonical forms.
1832 pub fn const_eval_resolve(
1834 param_env: ty::ParamEnv<'tcx>,
1836 substs: SubstsRef<'tcx>,
1837 promoted: Option<mir::Promoted>,
1839 ) -> ConstEvalResult<'tcx> {
1840 let mut original_values = OriginalQueryValues::default();
1841 let canonical = self.canonicalize_query(&(param_env, substs), &mut original_values);
1843 let (param_env, substs) = canonical.value;
1844 // The return value is the evaluated value which doesn't contain any reference to inference
1845 // variables, thus we don't need to substitute back the original values.
1846 self.tcx.const_eval_resolve(param_env, def_id, substs, promoted, span)
1849 /// If `typ` is a type variable of some kind, resolve it one level
1850 /// (but do not resolve types found in the result). If `typ` is
1851 /// not a type variable, just return it unmodified.
1852 // FIXME(eddyb) inline into `ShallowResolver::visit_ty`.
1853 fn shallow_resolve_ty(&self, typ: Ty<'tcx>) -> Ty<'tcx> {
1855 ty::Infer(ty::TyVar(v)) => {
1856 // Not entirely obvious: if `typ` is a type variable,
1857 // it can be resolved to an int/float variable, which
1858 // can then be recursively resolved, hence the
1859 // recursion. Note though that we prevent type
1860 // variables from unifying to other type variables
1861 // directly (though they may be embedded
1862 // structurally), and we prevent cycles in any case,
1863 // so this recursion should always be of very limited
1866 // Note: if these two lines are combined into one we get
1867 // dynamic borrow errors on `self.inner`.
1868 let known = self.inner.borrow_mut().type_variables().probe(v).known();
1869 known.map(|t| self.shallow_resolve_ty(t)).unwrap_or(typ)
1872 ty::Infer(ty::IntVar(v)) => self
1875 .int_unification_table()
1877 .map(|v| v.to_type(self.tcx))
1880 ty::Infer(ty::FloatVar(v)) => self
1883 .float_unification_table()
1885 .map(|v| v.to_type(self.tcx))
1892 /// `ty_or_const_infer_var_changed` is equivalent to one of these two:
1893 /// * `shallow_resolve(ty) != ty` (where `ty.kind = ty::Infer(_)`)
1894 /// * `shallow_resolve(ct) != ct` (where `ct.kind = ty::ConstKind::Infer(_)`)
1896 /// However, `ty_or_const_infer_var_changed` is more efficient. It's always
1897 /// inlined, despite being large, because it has only two call sites that
1898 /// are extremely hot (both in `traits::fulfill`'s checking of `stalled_on`
1899 /// inference variables), and it handles both `Ty` and `ty::Const` without
1900 /// having to resort to storing full `GenericArg`s in `stalled_on`.
1902 pub fn ty_or_const_infer_var_changed(&self, infer_var: TyOrConstInferVar<'tcx>) -> bool {
1904 TyOrConstInferVar::Ty(v) => {
1905 use self::type_variable::TypeVariableValue;
1907 // If `inlined_probe` returns a `Known` value, it never equals
1908 // `ty::Infer(ty::TyVar(v))`.
1909 match self.inner.borrow_mut().type_variables().inlined_probe(v) {
1910 TypeVariableValue::Unknown { .. } => false,
1911 TypeVariableValue::Known { .. } => true,
1915 TyOrConstInferVar::TyInt(v) => {
1916 // If `inlined_probe_value` returns a value it's always a
1917 // `ty::Int(_)` or `ty::UInt(_)`, which never matches a
1919 self.inner.borrow_mut().int_unification_table().inlined_probe_value(v).is_some()
1922 TyOrConstInferVar::TyFloat(v) => {
1923 // If `probe_value` returns a value it's always a
1924 // `ty::Float(_)`, which never matches a `ty::Infer(_)`.
1926 // Not `inlined_probe_value(v)` because this call site is colder.
1927 self.inner.borrow_mut().float_unification_table().probe_value(v).is_some()
1930 TyOrConstInferVar::Const(v) => {
1931 // If `probe_value` returns a `Known` value, it never equals
1932 // `ty::ConstKind::Infer(ty::InferConst::Var(v))`.
1934 // Not `inlined_probe_value(v)` because this call site is colder.
1935 match self.inner.borrow_mut().const_unification_table.probe_value(v).val {
1936 ConstVariableValue::Unknown { .. } => false,
1937 ConstVariableValue::Known { .. } => true,
1944 /// Helper for `ty_or_const_infer_var_changed` (see comment on that), currently
1945 /// used only for `traits::fulfill`'s list of `stalled_on` inference variables.
1946 #[derive(Copy, Clone, Debug)]
1947 pub enum TyOrConstInferVar<'tcx> {
1948 /// Equivalent to `ty::Infer(ty::TyVar(_))`.
1950 /// Equivalent to `ty::Infer(ty::IntVar(_))`.
1952 /// Equivalent to `ty::Infer(ty::FloatVar(_))`.
1955 /// Equivalent to `ty::ConstKind::Infer(ty::InferConst::Var(_))`.
1956 Const(ConstVid<'tcx>),
1959 impl TyOrConstInferVar<'tcx> {
1960 /// Tries to extract an inference variable from a type or a constant, returns `None`
1961 /// for types other than `ty::Infer(_)` (or `InferTy::Fresh*`) and
1962 /// for constants other than `ty::ConstKind::Infer(_)` (or `InferConst::Fresh`).
1963 pub fn maybe_from_generic_arg(arg: GenericArg<'tcx>) -> Option<Self> {
1964 match arg.unpack() {
1965 GenericArgKind::Type(ty) => Self::maybe_from_ty(ty),
1966 GenericArgKind::Const(ct) => Self::maybe_from_const(ct),
1967 GenericArgKind::Lifetime(_) => None,
1971 /// Tries to extract an inference variable from a type, returns `None`
1972 /// for types other than `ty::Infer(_)` (or `InferTy::Fresh*`).
1973 pub fn maybe_from_ty(ty: Ty<'tcx>) -> Option<Self> {
1975 ty::Infer(ty::TyVar(v)) => Some(TyOrConstInferVar::Ty(v)),
1976 ty::Infer(ty::IntVar(v)) => Some(TyOrConstInferVar::TyInt(v)),
1977 ty::Infer(ty::FloatVar(v)) => Some(TyOrConstInferVar::TyFloat(v)),
1982 /// Tries to extract an inference variable from a constant, returns `None`
1983 /// for constants other than `ty::ConstKind::Infer(_)` (or `InferConst::Fresh`).
1984 pub fn maybe_from_const(ct: &'tcx ty::Const<'tcx>) -> Option<Self> {
1986 ty::ConstKind::Infer(InferConst::Var(v)) => Some(TyOrConstInferVar::Const(v)),
1992 struct ShallowResolver<'a, 'tcx> {
1993 infcx: &'a InferCtxt<'a, 'tcx>,
1996 impl<'a, 'tcx> TypeFolder<'tcx> for ShallowResolver<'a, 'tcx> {
1997 fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
2001 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
2002 self.infcx.shallow_resolve_ty(ty)
2005 fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
2006 if let ty::Const { val: ty::ConstKind::Infer(InferConst::Var(vid)), .. } = ct {
2010 .const_unification_table()
2021 impl<'tcx> TypeTrace<'tcx> {
2022 pub fn span(&self) -> Span {
2027 cause: &ObligationCause<'tcx>,
2028 a_is_expected: bool,
2031 ) -> TypeTrace<'tcx> {
2032 TypeTrace { cause: cause.clone(), values: Types(ExpectedFound::new(a_is_expected, a, b)) }
2035 pub fn dummy(tcx: TyCtxt<'tcx>) -> TypeTrace<'tcx> {
2037 cause: ObligationCause::dummy(),
2038 values: Types(ExpectedFound { expected: tcx.types.err, found: tcx.types.err }),
2043 impl<'tcx> SubregionOrigin<'tcx> {
2044 pub fn span(&self) -> Span {
2046 Subtype(ref a) => a.span(),
2047 InfStackClosure(a) => a,
2048 InvokeClosure(a) => a,
2049 DerefPointer(a) => a,
2050 ClosureCapture(a, _) => a,
2052 RelateObjectBound(a) => a,
2053 RelateParamBound(a, _) => a,
2054 RelateRegionParamBound(a) => a,
2055 RelateDefaultParamBound(a, _) => a,
2057 ReborrowUpvar(a, _) => a,
2058 DataBorrowed(_, a) => a,
2059 ReferenceOutlivesReferent(_, a) => a,
2060 ParameterInScope(_, a) => a,
2061 ExprTypeIsNotInScope(_, a) => a,
2062 BindingTypeIsNotValidAtDecl(a) => a,
2069 SafeDestructor(a) => a,
2070 CompareImplMethodObligation { span, .. } => span,
2074 pub fn from_obligation_cause<F>(cause: &traits::ObligationCause<'tcx>, default: F) -> Self
2076 F: FnOnce() -> Self,
2079 traits::ObligationCauseCode::ReferenceOutlivesReferent(ref_type) => {
2080 SubregionOrigin::ReferenceOutlivesReferent(ref_type, cause.span)
2083 traits::ObligationCauseCode::CompareImplMethodObligation {
2087 } => SubregionOrigin::CompareImplMethodObligation {
2099 impl RegionVariableOrigin {
2100 pub fn span(&self) -> Span {
2102 MiscVariable(a) => a,
2103 PatternRegion(a) => a,
2104 AddrOfRegion(a) => a,
2107 EarlyBoundRegion(a, ..) => a,
2108 LateBoundRegion(a, ..) => a,
2109 BoundRegionInCoherence(_) => rustc_span::DUMMY_SP,
2110 UpvarRegion(_, a) => a,
2111 NLL(..) => bug!("NLL variable used with `span`"),
2116 impl<'tcx> fmt::Debug for RegionObligation<'tcx> {
2117 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2120 "RegionObligation(sub_region={:?}, sup_type={:?})",
2121 self.sub_region, self.sup_type