1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Trait Resolution. See README.md for an overview of how this works.
13 pub use self::SelectionError::*;
14 pub use self::FulfillmentErrorCode::*;
15 pub use self::Vtable::*;
16 pub use self::ObligationCauseCode::*;
19 use hir::def_id::DefId;
20 use middle::region::RegionMaps;
21 use middle::free_region::FreeRegionMap;
22 use ty::subst::Substs;
23 use ty::{self, Ty, TyCtxt, TypeFoldable, ToPredicate};
24 use ty::error::{ExpectedFound, TypeError};
25 use infer::{InferCtxt};
29 use syntax_pos::{Span, DUMMY_SP};
31 pub use self::error_reporting::TraitErrorKey;
32 pub use self::coherence::orphan_check;
33 pub use self::coherence::overlapping_impls;
34 pub use self::coherence::OrphanCheckErr;
35 pub use self::fulfill::{FulfillmentContext, GlobalFulfilledPredicates, RegionObligation};
36 pub use self::project::MismatchedProjectionTypes;
37 pub use self::project::{normalize, normalize_projection_type, Normalized};
38 pub use self::project::{ProjectionCache, ProjectionCacheSnapshot, Reveal};
39 pub use self::object_safety::ObjectSafetyViolation;
40 pub use self::object_safety::MethodViolationCode;
41 pub use self::select::{EvaluationCache, SelectionContext, SelectionCache};
42 pub use self::specialize::{OverlapError, specialization_graph, specializes, translate_substs};
43 pub use self::specialize::{SpecializesCache, find_associated_item};
44 pub use self::util::elaborate_predicates;
45 pub use self::util::supertraits;
46 pub use self::util::Supertraits;
47 pub use self::util::supertrait_def_ids;
48 pub use self::util::SupertraitDefIds;
49 pub use self::util::transitive_bounds;
62 /// An `Obligation` represents some trait reference (e.g. `int:Eq`) for
63 /// which the vtable must be found. The process of finding a vtable is
64 /// called "resolving" the `Obligation`. This process consists of
65 /// either identifying an `impl` (e.g., `impl Eq for int`) that
66 /// provides the required vtable, or else finding a bound that is in
67 /// scope. The eventual result is usually a `Selection` (defined below).
68 #[derive(Clone, PartialEq, Eq)]
69 pub struct Obligation<'tcx, T> {
70 pub cause: ObligationCause<'tcx>,
71 pub recursion_depth: usize,
75 pub type PredicateObligation<'tcx> = Obligation<'tcx, ty::Predicate<'tcx>>;
76 pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
78 /// Why did we incur this obligation? Used for error reporting.
79 #[derive(Clone, Debug, PartialEq, Eq)]
80 pub struct ObligationCause<'tcx> {
83 // The id of the fn body that triggered this obligation. This is
84 // used for region obligations to determine the precise
85 // environment in which the region obligation should be evaluated
86 // (in particular, closures can add new assumptions). See the
87 // field `region_obligations` of the `FulfillmentContext` for more
89 pub body_id: ast::NodeId,
91 pub code: ObligationCauseCode<'tcx>
94 #[derive(Clone, Debug, PartialEq, Eq)]
95 pub enum ObligationCauseCode<'tcx> {
96 /// Not well classified or should be obvious from span.
99 /// A slice or array is WF only if `T: Sized`
102 /// A tuple is WF only if its middle elements are Sized
105 /// This is the trait reference from the given projection
106 ProjectionWf(ty::ProjectionTy<'tcx>),
108 /// In an impl of trait X for type Y, type Y must
109 /// also implement all supertraits of X.
110 ItemObligation(DefId),
112 /// A type like `&'a T` is WF only if `T: 'a`.
113 ReferenceOutlivesReferent(Ty<'tcx>),
115 /// A type like `Box<Foo<'a> + 'b>` is WF only if `'b: 'a`.
116 ObjectTypeBound(Ty<'tcx>, ty::Region<'tcx>),
118 /// Obligation incurred due to an object cast.
119 ObjectCastObligation(/* Object type */ Ty<'tcx>),
121 /// Various cases where expressions must be sized/copy/etc:
122 AssignmentLhsSized, // L = X implies that L is Sized
123 StructInitializerSized, // S { ... } must be Sized
124 VariableType(ast::NodeId), // Type of each variable must be Sized
125 ReturnType, // Return type must be Sized
126 RepeatVec, // [T,..n] --> T must be Copy
128 // Types of fields (other than the last) in a struct must be sized.
131 // Constant expressions must be sized.
134 // static items must have `Sync` type
137 BuiltinDerivedObligation(DerivedObligationCause<'tcx>),
139 ImplDerivedObligation(DerivedObligationCause<'tcx>),
141 // error derived when matching traits/impls; see ObligationCause for more details
142 CompareImplMethodObligation {
143 item_name: ast::Name,
144 impl_item_def_id: DefId,
145 trait_item_def_id: DefId,
146 lint_id: Option<ast::NodeId>,
149 // Checking that this expression can be assigned where it needs to be
150 // FIXME(eddyb) #11161 is the original Expr required?
153 // Computing common supertype in the arms of a match expression
154 MatchExpressionArm { arm_span: Span,
155 source: hir::MatchSource },
157 // Computing common supertype in an if expression
160 // Computing common supertype of an if expression with no else counter-part
161 IfExpressionWithNoElse,
166 // `main` has wrong type
169 // `start` has wrong type
172 // intrinsic has wrong type
178 // `return` with no expression
182 #[derive(Clone, Debug, PartialEq, Eq)]
183 pub struct DerivedObligationCause<'tcx> {
184 /// The trait reference of the parent obligation that led to the
185 /// current obligation. Note that only trait obligations lead to
186 /// derived obligations, so we just store the trait reference here
188 parent_trait_ref: ty::PolyTraitRef<'tcx>,
190 /// The parent trait had this cause
191 parent_code: Rc<ObligationCauseCode<'tcx>>
194 pub type Obligations<'tcx, O> = Vec<Obligation<'tcx, O>>;
195 pub type PredicateObligations<'tcx> = Vec<PredicateObligation<'tcx>>;
196 pub type TraitObligations<'tcx> = Vec<TraitObligation<'tcx>>;
198 pub type Selection<'tcx> = Vtable<'tcx, PredicateObligation<'tcx>>;
200 #[derive(Clone,Debug)]
201 pub enum SelectionError<'tcx> {
203 OutputTypeParameterMismatch(ty::PolyTraitRef<'tcx>,
204 ty::PolyTraitRef<'tcx>,
205 ty::error::TypeError<'tcx>),
206 TraitNotObjectSafe(DefId),
209 pub struct FulfillmentError<'tcx> {
210 pub obligation: PredicateObligation<'tcx>,
211 pub code: FulfillmentErrorCode<'tcx>
215 pub enum FulfillmentErrorCode<'tcx> {
216 CodeSelectionError(SelectionError<'tcx>),
217 CodeProjectionError(MismatchedProjectionTypes<'tcx>),
218 CodeSubtypeError(ExpectedFound<Ty<'tcx>>,
219 TypeError<'tcx>), // always comes from a SubtypePredicate
223 /// When performing resolution, it is typically the case that there
224 /// can be one of three outcomes:
226 /// - `Ok(Some(r))`: success occurred with result `r`
227 /// - `Ok(None)`: could not definitely determine anything, usually due
228 /// to inconclusive type inference.
229 /// - `Err(e)`: error `e` occurred
230 pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>;
232 /// Given the successful resolution of an obligation, the `Vtable`
233 /// indicates where the vtable comes from. Note that while we call this
234 /// a "vtable", it does not necessarily indicate dynamic dispatch at
235 /// runtime. `Vtable` instances just tell the compiler where to find
236 /// methods, but in generic code those methods are typically statically
237 /// dispatched -- only when an object is constructed is a `Vtable`
238 /// instance reified into an actual vtable.
240 /// For example, the vtable may be tied to a specific impl (case A),
241 /// or it may be relative to some bound that is in scope (case B).
245 /// impl<T:Clone> Clone<T> for Option<T> { ... } // Impl_1
246 /// impl<T:Clone> Clone<T> for Box<T> { ... } // Impl_2
247 /// impl Clone for int { ... } // Impl_3
249 /// fn foo<T:Clone>(concrete: Option<Box<int>>,
251 /// mixed: Option<T>) {
253 /// // Case A: Vtable points at a specific impl. Only possible when
254 /// // type is concretely known. If the impl itself has bounded
255 /// // type parameters, Vtable will carry resolutions for those as well:
256 /// concrete.clone(); // Vtable(Impl_1, [Vtable(Impl_2, [Vtable(Impl_3)])])
258 /// // Case B: Vtable must be provided by caller. This applies when
259 /// // type is a type parameter.
260 /// param.clone(); // VtableParam
262 /// // Case C: A mix of cases A and B.
263 /// mixed.clone(); // Vtable(Impl_1, [VtableParam])
267 /// ### The type parameter `N`
269 /// See explanation on `VtableImplData`.
271 pub enum Vtable<'tcx, N> {
272 /// Vtable identifying a particular impl.
273 VtableImpl(VtableImplData<'tcx, N>),
275 /// Vtable for default trait implementations
276 /// This carries the information and nested obligations with regards
277 /// to a default implementation for a trait `Trait`. The nested obligations
278 /// ensure the trait implementation holds for all the constituent types.
279 VtableDefaultImpl(VtableDefaultImplData<N>),
281 /// Successful resolution to an obligation provided by the caller
282 /// for some type parameter. The `Vec<N>` represents the
283 /// obligations incurred from normalizing the where-clause (if
287 /// Virtual calls through an object
288 VtableObject(VtableObjectData<'tcx, N>),
290 /// Successful resolution for a builtin trait.
291 VtableBuiltin(VtableBuiltinData<N>),
293 /// Vtable automatically generated for a closure. The def ID is the ID
294 /// of the closure expression. This is a `VtableImpl` in spirit, but the
295 /// impl is generated by the compiler and does not appear in the source.
296 VtableClosure(VtableClosureData<'tcx, N>),
298 /// Same as above, but for a fn pointer type with the given signature.
299 VtableFnPointer(VtableFnPointerData<'tcx, N>),
302 /// Identifies a particular impl in the source, along with a set of
303 /// substitutions from the impl's type/lifetime parameters. The
304 /// `nested` vector corresponds to the nested obligations attached to
305 /// the impl's type parameters.
307 /// The type parameter `N` indicates the type used for "nested
308 /// obligations" that are required by the impl. During type check, this
309 /// is `Obligation`, as one might expect. During trans, however, this
310 /// is `()`, because trans only requires a shallow resolution of an
311 /// impl, and nested obligations are satisfied later.
312 #[derive(Clone, PartialEq, Eq)]
313 pub struct VtableImplData<'tcx, N> {
314 pub impl_def_id: DefId,
315 pub substs: &'tcx Substs<'tcx>,
319 #[derive(Clone, PartialEq, Eq)]
320 pub struct VtableClosureData<'tcx, N> {
321 pub closure_def_id: DefId,
322 pub substs: ty::ClosureSubsts<'tcx>,
323 /// Nested obligations. This can be non-empty if the closure
324 /// signature contains associated types.
329 pub struct VtableDefaultImplData<N> {
330 pub trait_def_id: DefId,
335 pub struct VtableBuiltinData<N> {
339 /// A vtable for some object-safe trait `Foo` automatically derived
340 /// for the object type `Foo`.
341 #[derive(PartialEq,Eq,Clone)]
342 pub struct VtableObjectData<'tcx, N> {
343 /// `Foo` upcast to the obligation trait. This will be some supertrait of `Foo`.
344 pub upcast_trait_ref: ty::PolyTraitRef<'tcx>,
346 /// The vtable is formed by concatenating together the method lists of
347 /// the base object trait and all supertraits; this is the start of
348 /// `upcast_trait_ref`'s methods in that vtable.
349 pub vtable_base: usize,
354 #[derive(Clone, PartialEq, Eq)]
355 pub struct VtableFnPointerData<'tcx, N> {
356 pub fn_ty: ty::Ty<'tcx>,
360 /// Creates predicate obligations from the generic bounds.
361 pub fn predicates_for_generics<'tcx>(cause: ObligationCause<'tcx>,
362 generic_bounds: &ty::InstantiatedPredicates<'tcx>)
363 -> PredicateObligations<'tcx>
365 util::predicates_for_generics(cause, 0, generic_bounds)
368 /// Determines whether the type `ty` is known to meet `bound` and
369 /// returns true if so. Returns false if `ty` either does not meet
370 /// `bound` or is not known to meet bound (note that this is
371 /// conservative towards *no impl*, which is the opposite of the
372 /// `evaluate` methods).
373 pub fn type_known_to_meet_bound<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
379 debug!("type_known_to_meet_bound(ty={:?}, bound={:?})",
381 infcx.tcx.item_path_str(def_id));
383 let trait_ref = ty::TraitRef {
385 substs: infcx.tcx.mk_substs_trait(ty, &[]),
387 let obligation = Obligation {
388 cause: ObligationCause::misc(span, ast::DUMMY_NODE_ID),
390 predicate: trait_ref.to_predicate(),
393 let result = SelectionContext::new(infcx)
394 .evaluate_obligation_conservatively(&obligation);
395 debug!("type_known_to_meet_ty={:?} bound={} => {:?}",
396 ty, infcx.tcx.item_path_str(def_id), result);
398 if result && (ty.has_infer_types() || ty.has_closure_types()) {
399 // Because of inference "guessing", selection can sometimes claim
400 // to succeed while the success requires a guess. To ensure
401 // this function's result remains infallible, we must confirm
402 // that guess. While imperfect, I believe this is sound.
404 let mut fulfill_cx = FulfillmentContext::new();
406 // We can use a dummy node-id here because we won't pay any mind
407 // to region obligations that arise (there shouldn't really be any
409 let cause = ObligationCause::misc(span, ast::DUMMY_NODE_ID);
411 fulfill_cx.register_bound(infcx, ty, def_id, cause);
413 // Note: we only assume something is `Copy` if we can
414 // *definitively* show that it implements `Copy`. Otherwise,
415 // assume it is move; linear is always ok.
416 match fulfill_cx.select_all_or_error(infcx) {
418 debug!("type_known_to_meet_bound: ty={:?} bound={} success",
420 infcx.tcx.item_path_str(def_id));
424 debug!("type_known_to_meet_bound: ty={:?} bound={} errors={:?}",
426 infcx.tcx.item_path_str(def_id),
436 // FIXME: this is gonna need to be removed ...
437 /// Normalizes the parameter environment, reporting errors if they occur.
438 pub fn normalize_param_env_or_error<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
439 region_context: DefId,
440 unnormalized_env: ty::ParameterEnvironment<'tcx>,
441 cause: ObligationCause<'tcx>)
442 -> ty::ParameterEnvironment<'tcx>
444 // I'm not wild about reporting errors here; I'd prefer to
445 // have the errors get reported at a defined place (e.g.,
446 // during typeck). Instead I have all parameter
447 // environments, in effect, going through this function
448 // and hence potentially reporting errors. This ensurse of
449 // course that we never forget to normalize (the
450 // alternative seemed like it would involve a lot of
451 // manual invocations of this fn -- and then we'd have to
452 // deal with the errors at each of those sites).
454 // In any case, in practice, typeck constructs all the
455 // parameter environments once for every fn as it goes,
456 // and errors will get reported then; so after typeck we
457 // can be sure that no errors should occur.
459 let span = cause.span;
461 debug!("normalize_param_env_or_error(unnormalized_env={:?})",
464 let predicates: Vec<_> =
465 util::elaborate_predicates(tcx, unnormalized_env.caller_bounds.to_vec())
466 .filter(|p| !p.is_global()) // (*)
469 // (*) Any predicate like `i32: Trait<u32>` or whatever doesn't
470 // need to be in the *environment* to be proven, so screen those
471 // out. This is important for the soundness of inter-fn
472 // caching. Note though that we should probably check that these
473 // predicates hold at the point where the environment is
474 // constructed, but I am not currently doing so out of laziness.
477 debug!("normalize_param_env_or_error: elaborated-predicates={:?}",
480 let elaborated_env = unnormalized_env.with_caller_bounds(tcx.intern_predicates(&predicates));
482 tcx.infer_ctxt(elaborated_env, Reveal::UserFacing).enter(|infcx| {
483 let predicates = match fully_normalize(
485 // You would really want to pass infcx.parameter_environment.caller_bounds here,
486 // but that is an interned slice, and fully_normalize takes &T and returns T, so
487 // without further refactoring, a slice can't be used. Luckily, we still have the
488 // predicate vector from which we created the ParameterEnvironment in infcx, so we
489 // can pass that instead. It's roundabout and a bit brittle, but this code path
490 // ought to be refactored anyway, and until then it saves us from having to copy.
493 Ok(predicates) => predicates,
495 infcx.report_fulfillment_errors(&errors);
496 // An unnormalized env is better than nothing.
497 return infcx.parameter_environment;
501 debug!("normalize_param_env_or_error: normalized predicates={:?}",
504 let region_maps = RegionMaps::new();
505 let free_regions = FreeRegionMap::new();
506 infcx.resolve_regions_and_report_errors(region_context, ®ion_maps, &free_regions);
507 let predicates = match infcx.fully_resolve(&predicates) {
508 Ok(predicates) => predicates,
510 // If we encounter a fixup error, it means that some type
511 // variable wound up unconstrained. I actually don't know
512 // if this can happen, and I certainly don't expect it to
513 // happen often, but if it did happen it probably
514 // represents a legitimate failure due to some kind of
515 // unconstrained variable, and it seems better not to ICE,
516 // all things considered.
517 tcx.sess.span_err(span, &fixup_err.to_string());
518 // An unnormalized env is better than nothing.
519 return infcx.parameter_environment;
523 let predicates = match tcx.lift_to_global(&predicates) {
524 Some(predicates) => predicates,
525 None => return infcx.parameter_environment
528 debug!("normalize_param_env_or_error: resolved predicates={:?}",
531 infcx.parameter_environment.with_caller_bounds(tcx.intern_predicates(&predicates))
535 pub fn fully_normalize<'a, 'gcx, 'tcx, T>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
536 cause: ObligationCause<'tcx>,
538 -> Result<T, Vec<FulfillmentError<'tcx>>>
539 where T : TypeFoldable<'tcx>
541 debug!("fully_normalize(value={:?})", value);
543 let mut selcx = &mut SelectionContext::new(infcx);
544 // FIXME (@jroesch) ISSUE 26721
545 // I'm not sure if this is a bug or not, needs further investigation.
546 // It appears that by reusing the fulfillment_cx here we incur more
547 // obligations and later trip an asssertion on regionck.rs line 337.
549 // The two possibilities I see is:
550 // - normalization is not actually fully happening and we
551 // have a bug else where
552 // - we are adding a duplicate bound into the list causing
553 // its size to change.
555 // I think we should probably land this refactor and then come
556 // back to this is a follow-up patch.
557 let mut fulfill_cx = FulfillmentContext::new();
559 let Normalized { value: normalized_value, obligations } =
560 project::normalize(selcx, cause, value);
561 debug!("fully_normalize: normalized_value={:?} obligations={:?}",
564 for obligation in obligations {
565 fulfill_cx.register_predicate_obligation(selcx.infcx(), obligation);
568 debug!("fully_normalize: select_all_or_error start");
569 match fulfill_cx.select_all_or_error(infcx) {
572 debug!("fully_normalize: error={:?}", e);
576 debug!("fully_normalize: select_all_or_error complete");
577 let resolved_value = infcx.resolve_type_vars_if_possible(&normalized_value);
578 debug!("fully_normalize: resolved_value={:?}", resolved_value);
582 /// Normalizes the predicates and checks whether they hold. If this
583 /// returns false, then either normalize encountered an error or one
584 /// of the predicates did not hold. Used when creating vtables to
585 /// check for unsatisfiable methods.
586 pub fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
587 predicates: Vec<ty::Predicate<'tcx>>)
590 debug!("normalize_and_test_predicates(predicates={:?})",
593 tcx.infer_ctxt((), Reveal::All).enter(|infcx| {
594 let mut selcx = SelectionContext::new(&infcx);
595 let mut fulfill_cx = FulfillmentContext::new();
596 let cause = ObligationCause::dummy();
597 let Normalized { value: predicates, obligations } =
598 normalize(&mut selcx, cause.clone(), &predicates);
599 for obligation in obligations {
600 fulfill_cx.register_predicate_obligation(&infcx, obligation);
602 for predicate in predicates {
603 let obligation = Obligation::new(cause.clone(), predicate);
604 fulfill_cx.register_predicate_obligation(&infcx, obligation);
607 fulfill_cx.select_all_or_error(&infcx).is_ok()
611 /// Given a trait `trait_ref`, iterates the vtable entries
612 /// that come from `trait_ref`, including its supertraits.
613 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
614 pub fn get_vtable_methods<'a, 'tcx>(
615 tcx: TyCtxt<'a, 'tcx, 'tcx>,
616 trait_ref: ty::PolyTraitRef<'tcx>)
617 -> impl Iterator<Item=Option<(DefId, &'tcx Substs<'tcx>)>> + 'a
619 debug!("get_vtable_methods({:?})", trait_ref);
621 supertraits(tcx, trait_ref).flat_map(move |trait_ref| {
622 let trait_methods = tcx.associated_items(trait_ref.def_id())
623 .filter(|item| item.kind == ty::AssociatedKind::Method);
625 // Now list each method's DefId and Substs (for within its trait).
626 // If the method can never be called from this object, produce None.
627 trait_methods.map(move |trait_method| {
628 debug!("get_vtable_methods: trait_method={:?}", trait_method);
629 let def_id = trait_method.def_id;
631 // Some methods cannot be called on an object; skip those.
632 if !tcx.is_vtable_safe_method(trait_ref.def_id(), &trait_method) {
633 debug!("get_vtable_methods: not vtable safe");
637 // the method may have some early-bound lifetimes, add
639 let substs = Substs::for_item(tcx, def_id,
640 |_, _| tcx.types.re_erased,
641 |def, _| trait_ref.substs().type_for_def(def));
643 // the trait type may have higher-ranked lifetimes in it;
644 // so erase them if they appear, so that we get the type
645 // at some particular call site
646 let substs = tcx.erase_late_bound_regions_and_normalize(&ty::Binder(substs));
648 // It's possible that the method relies on where clauses that
649 // do not hold for this particular set of type parameters.
650 // Note that this method could then never be called, so we
651 // do not want to try and trans it, in that case (see #23435).
652 let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
653 if !normalize_and_test_predicates(tcx, predicates.predicates) {
654 debug!("get_vtable_methods: predicates do not hold");
658 Some((def_id, substs))
663 impl<'tcx,O> Obligation<'tcx,O> {
664 pub fn new(cause: ObligationCause<'tcx>,
666 -> Obligation<'tcx, O>
668 Obligation { cause: cause,
670 predicate: trait_ref }
673 fn with_depth(cause: ObligationCause<'tcx>,
674 recursion_depth: usize,
676 -> Obligation<'tcx, O>
678 Obligation { cause: cause,
679 recursion_depth: recursion_depth,
680 predicate: trait_ref }
683 pub fn misc(span: Span, body_id: ast::NodeId, trait_ref: O) -> Obligation<'tcx, O> {
684 Obligation::new(ObligationCause::misc(span, body_id), trait_ref)
687 pub fn with<P>(&self, value: P) -> Obligation<'tcx,P> {
688 Obligation { cause: self.cause.clone(),
689 recursion_depth: self.recursion_depth,
694 impl<'tcx> ObligationCause<'tcx> {
695 pub fn new(span: Span,
696 body_id: ast::NodeId,
697 code: ObligationCauseCode<'tcx>)
698 -> ObligationCause<'tcx> {
699 ObligationCause { span: span, body_id: body_id, code: code }
702 pub fn misc(span: Span, body_id: ast::NodeId) -> ObligationCause<'tcx> {
703 ObligationCause { span: span, body_id: body_id, code: MiscObligation }
706 pub fn dummy() -> ObligationCause<'tcx> {
707 ObligationCause { span: DUMMY_SP, body_id: ast::CRATE_NODE_ID, code: MiscObligation }
711 impl<'tcx, N> Vtable<'tcx, N> {
712 pub fn nested_obligations(self) -> Vec<N> {
714 VtableImpl(i) => i.nested,
716 VtableBuiltin(i) => i.nested,
717 VtableDefaultImpl(d) => d.nested,
718 VtableClosure(c) => c.nested,
719 VtableObject(d) => d.nested,
720 VtableFnPointer(d) => d.nested,
724 fn nested_obligations_mut(&mut self) -> &mut Vec<N> {
726 &mut VtableImpl(ref mut i) => &mut i.nested,
727 &mut VtableParam(ref mut n) => n,
728 &mut VtableBuiltin(ref mut i) => &mut i.nested,
729 &mut VtableDefaultImpl(ref mut d) => &mut d.nested,
730 &mut VtableClosure(ref mut c) => &mut c.nested,
731 &mut VtableObject(ref mut d) => &mut d.nested,
732 &mut VtableFnPointer(ref mut d) => &mut d.nested,
736 pub fn map<M, F>(self, f: F) -> Vtable<'tcx, M> where F: FnMut(N) -> M {
738 VtableImpl(i) => VtableImpl(VtableImplData {
739 impl_def_id: i.impl_def_id,
741 nested: i.nested.into_iter().map(f).collect(),
743 VtableParam(n) => VtableParam(n.into_iter().map(f).collect()),
744 VtableBuiltin(i) => VtableBuiltin(VtableBuiltinData {
745 nested: i.nested.into_iter().map(f).collect(),
747 VtableObject(o) => VtableObject(VtableObjectData {
748 upcast_trait_ref: o.upcast_trait_ref,
749 vtable_base: o.vtable_base,
750 nested: o.nested.into_iter().map(f).collect(),
752 VtableDefaultImpl(d) => VtableDefaultImpl(VtableDefaultImplData {
753 trait_def_id: d.trait_def_id,
754 nested: d.nested.into_iter().map(f).collect(),
756 VtableFnPointer(p) => VtableFnPointer(VtableFnPointerData {
758 nested: p.nested.into_iter().map(f).collect(),
760 VtableClosure(c) => VtableClosure(VtableClosureData {
761 closure_def_id: c.closure_def_id,
763 nested: c.nested.into_iter().map(f).collect(),
769 impl<'tcx> FulfillmentError<'tcx> {
770 fn new(obligation: PredicateObligation<'tcx>,
771 code: FulfillmentErrorCode<'tcx>)
772 -> FulfillmentError<'tcx>
774 FulfillmentError { obligation: obligation, code: code }
778 impl<'tcx> TraitObligation<'tcx> {
779 fn self_ty(&self) -> ty::Binder<Ty<'tcx>> {
780 ty::Binder(self.predicate.skip_binder().self_ty())
784 pub fn provide(providers: &mut ty::maps::Providers) {
785 *providers = ty::maps::Providers {
786 is_object_safe: object_safety::is_object_safe_provider,
787 specialization_graph_of: specialize::specialization_graph_provider,
792 pub fn provide_extern(providers: &mut ty::maps::Providers) {
793 *providers = ty::maps::Providers {
794 is_object_safe: object_safety::is_object_safe_provider,
795 specialization_graph_of: specialize::specialization_graph_provider,