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::free_region::FreeRegionMap;
21 use ty::subst::Substs;
22 use ty::{self, Ty, TyCtxt, TypeFoldable, ToPredicate};
27 use syntax_pos::{Span, DUMMY_SP};
29 pub use self::error_reporting::TraitErrorKey;
30 pub use self::coherence::orphan_check;
31 pub use self::coherence::overlapping_impls;
32 pub use self::coherence::OrphanCheckErr;
33 pub use self::fulfill::{FulfillmentContext, GlobalFulfilledPredicates, RegionObligation};
34 pub use self::project::MismatchedProjectionTypes;
35 pub use self::project::{normalize, normalize_projection_type, Normalized};
36 pub use self::project::{ProjectionCache, ProjectionCacheSnapshot, Reveal};
37 pub use self::object_safety::ObjectSafetyViolation;
38 pub use self::object_safety::MethodViolationCode;
39 pub use self::select::{EvaluationCache, SelectionContext, SelectionCache};
40 pub use self::select::{MethodMatchResult, MethodMatched, MethodAmbiguous, MethodDidNotMatch};
41 pub use self::select::{MethodMatchedData}; // intentionally don't export variants
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;
61 /// An `Obligation` represents some trait reference (e.g. `int:Eq`) for
62 /// which the vtable must be found. The process of finding a vtable is
63 /// called "resolving" the `Obligation`. This process consists of
64 /// either identifying an `impl` (e.g., `impl Eq for int`) that
65 /// provides the required vtable, or else finding a bound that is in
66 /// scope. The eventual result is usually a `Selection` (defined below).
67 #[derive(Clone, PartialEq, Eq)]
68 pub struct Obligation<'tcx, T> {
69 pub cause: ObligationCause<'tcx>,
70 pub recursion_depth: usize,
74 pub type PredicateObligation<'tcx> = Obligation<'tcx, ty::Predicate<'tcx>>;
75 pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
77 /// Why did we incur this obligation? Used for error reporting.
78 #[derive(Clone, Debug, PartialEq, Eq)]
79 pub struct ObligationCause<'tcx> {
82 // The id of the fn body that triggered this obligation. This is
83 // used for region obligations to determine the precise
84 // environment in which the region obligation should be evaluated
85 // (in particular, closures can add new assumptions). See the
86 // field `region_obligations` of the `FulfillmentContext` for more
88 pub body_id: ast::NodeId,
90 pub code: ObligationCauseCode<'tcx>
93 #[derive(Clone, Debug, PartialEq, Eq)]
94 pub enum ObligationCauseCode<'tcx> {
95 /// Not well classified or should be obvious from span.
98 /// A slice or array is WF only if `T: Sized`
101 /// A tuple is WF only if its middle elements are Sized
104 /// This is the trait reference from the given projection
105 ProjectionWf(ty::ProjectionTy<'tcx>),
107 /// In an impl of trait X for type Y, type Y must
108 /// also implement all supertraits of X.
109 ItemObligation(DefId),
111 /// A type like `&'a T` is WF only if `T: 'a`.
112 ReferenceOutlivesReferent(Ty<'tcx>),
114 /// A type like `Box<Foo<'a> + 'b>` is WF only if `'b: 'a`.
115 ObjectTypeBound(Ty<'tcx>, &'tcx ty::Region),
117 /// Obligation incurred due to an object cast.
118 ObjectCastObligation(/* Object type */ Ty<'tcx>),
120 /// Various cases where expressions must be sized/copy/etc:
121 AssignmentLhsSized, // L = X implies that L is Sized
122 StructInitializerSized, // S { ... } must be Sized
123 VariableType(ast::NodeId), // Type of each variable must be Sized
124 ReturnType, // Return type must be Sized
125 RepeatVec, // [T,..n] --> T must be Copy
127 // Types of fields (other than the last) in a struct must be sized.
130 // Constant expressions must be sized.
133 // static items must have `Sync` type
136 BuiltinDerivedObligation(DerivedObligationCause<'tcx>),
138 ImplDerivedObligation(DerivedObligationCause<'tcx>),
140 // error derived when matching traits/impls; see ObligationCause for more details
141 CompareImplMethodObligation {
142 item_name: ast::Name,
143 impl_item_def_id: DefId,
144 trait_item_def_id: DefId,
145 lint_id: Option<ast::NodeId>,
148 // Checking that this expression can be assigned where it needs to be
149 // FIXME(eddyb) #11161 is the original Expr required?
152 // Computing common supertype in the arms of a match expression
153 MatchExpressionArm { arm_span: Span,
154 source: hir::MatchSource },
156 // Computing common supertype in an if expression
159 // Computing common supertype of an if expression with no else counter-part
160 IfExpressionWithNoElse,
165 // `main` has wrong type
168 // `start` has wrong type
171 // intrinsic has wrong type
178 #[derive(Clone, Debug, PartialEq, Eq)]
179 pub struct DerivedObligationCause<'tcx> {
180 /// The trait reference of the parent obligation that led to the
181 /// current obligation. Note that only trait obligations lead to
182 /// derived obligations, so we just store the trait reference here
184 parent_trait_ref: ty::PolyTraitRef<'tcx>,
186 /// The parent trait had this cause
187 parent_code: Rc<ObligationCauseCode<'tcx>>
190 pub type Obligations<'tcx, O> = Vec<Obligation<'tcx, O>>;
191 pub type PredicateObligations<'tcx> = Vec<PredicateObligation<'tcx>>;
192 pub type TraitObligations<'tcx> = Vec<TraitObligation<'tcx>>;
194 pub type Selection<'tcx> = Vtable<'tcx, PredicateObligation<'tcx>>;
196 #[derive(Clone,Debug)]
197 pub enum SelectionError<'tcx> {
199 OutputTypeParameterMismatch(ty::PolyTraitRef<'tcx>,
200 ty::PolyTraitRef<'tcx>,
201 ty::error::TypeError<'tcx>),
202 TraitNotObjectSafe(DefId),
205 pub struct FulfillmentError<'tcx> {
206 pub obligation: PredicateObligation<'tcx>,
207 pub code: FulfillmentErrorCode<'tcx>
211 pub enum FulfillmentErrorCode<'tcx> {
212 CodeSelectionError(SelectionError<'tcx>),
213 CodeProjectionError(MismatchedProjectionTypes<'tcx>),
217 /// When performing resolution, it is typically the case that there
218 /// can be one of three outcomes:
220 /// - `Ok(Some(r))`: success occurred with result `r`
221 /// - `Ok(None)`: could not definitely determine anything, usually due
222 /// to inconclusive type inference.
223 /// - `Err(e)`: error `e` occurred
224 pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>;
226 /// Given the successful resolution of an obligation, the `Vtable`
227 /// indicates where the vtable comes from. Note that while we call this
228 /// a "vtable", it does not necessarily indicate dynamic dispatch at
229 /// runtime. `Vtable` instances just tell the compiler where to find
230 /// methods, but in generic code those methods are typically statically
231 /// dispatched -- only when an object is constructed is a `Vtable`
232 /// instance reified into an actual vtable.
234 /// For example, the vtable may be tied to a specific impl (case A),
235 /// or it may be relative to some bound that is in scope (case B).
239 /// impl<T:Clone> Clone<T> for Option<T> { ... } // Impl_1
240 /// impl<T:Clone> Clone<T> for Box<T> { ... } // Impl_2
241 /// impl Clone for int { ... } // Impl_3
243 /// fn foo<T:Clone>(concrete: Option<Box<int>>,
245 /// mixed: Option<T>) {
247 /// // Case A: Vtable points at a specific impl. Only possible when
248 /// // type is concretely known. If the impl itself has bounded
249 /// // type parameters, Vtable will carry resolutions for those as well:
250 /// concrete.clone(); // Vtable(Impl_1, [Vtable(Impl_2, [Vtable(Impl_3)])])
252 /// // Case B: Vtable must be provided by caller. This applies when
253 /// // type is a type parameter.
254 /// param.clone(); // VtableParam
256 /// // Case C: A mix of cases A and B.
257 /// mixed.clone(); // Vtable(Impl_1, [VtableParam])
261 /// ### The type parameter `N`
263 /// See explanation on `VtableImplData`.
265 pub enum Vtable<'tcx, N> {
266 /// Vtable identifying a particular impl.
267 VtableImpl(VtableImplData<'tcx, N>),
269 /// Vtable for default trait implementations
270 /// This carries the information and nested obligations with regards
271 /// to a default implementation for a trait `Trait`. The nested obligations
272 /// ensure the trait implementation holds for all the constituent types.
273 VtableDefaultImpl(VtableDefaultImplData<N>),
275 /// Successful resolution to an obligation provided by the caller
276 /// for some type parameter. The `Vec<N>` represents the
277 /// obligations incurred from normalizing the where-clause (if
281 /// Virtual calls through an object
282 VtableObject(VtableObjectData<'tcx, N>),
284 /// Successful resolution for a builtin trait.
285 VtableBuiltin(VtableBuiltinData<N>),
287 /// Vtable automatically generated for a closure. The def ID is the ID
288 /// of the closure expression. This is a `VtableImpl` in spirit, but the
289 /// impl is generated by the compiler and does not appear in the source.
290 VtableClosure(VtableClosureData<'tcx, N>),
292 /// Same as above, but for a fn pointer type with the given signature.
293 VtableFnPointer(VtableFnPointerData<'tcx, N>),
296 /// Identifies a particular impl in the source, along with a set of
297 /// substitutions from the impl's type/lifetime parameters. The
298 /// `nested` vector corresponds to the nested obligations attached to
299 /// the impl's type parameters.
301 /// The type parameter `N` indicates the type used for "nested
302 /// obligations" that are required by the impl. During type check, this
303 /// is `Obligation`, as one might expect. During trans, however, this
304 /// is `()`, because trans only requires a shallow resolution of an
305 /// impl, and nested obligations are satisfied later.
306 #[derive(Clone, PartialEq, Eq)]
307 pub struct VtableImplData<'tcx, N> {
308 pub impl_def_id: DefId,
309 pub substs: &'tcx Substs<'tcx>,
313 #[derive(Clone, PartialEq, Eq)]
314 pub struct VtableClosureData<'tcx, N> {
315 pub closure_def_id: DefId,
316 pub substs: ty::ClosureSubsts<'tcx>,
317 /// Nested obligations. This can be non-empty if the closure
318 /// signature contains associated types.
323 pub struct VtableDefaultImplData<N> {
324 pub trait_def_id: DefId,
329 pub struct VtableBuiltinData<N> {
333 /// A vtable for some object-safe trait `Foo` automatically derived
334 /// for the object type `Foo`.
335 #[derive(PartialEq,Eq,Clone)]
336 pub struct VtableObjectData<'tcx, N> {
337 /// `Foo` upcast to the obligation trait. This will be some supertrait of `Foo`.
338 pub upcast_trait_ref: ty::PolyTraitRef<'tcx>,
340 /// The vtable is formed by concatenating together the method lists of
341 /// the base object trait and all supertraits; this is the start of
342 /// `upcast_trait_ref`'s methods in that vtable.
343 pub vtable_base: usize,
348 #[derive(Clone, PartialEq, Eq)]
349 pub struct VtableFnPointerData<'tcx, N> {
350 pub fn_ty: ty::Ty<'tcx>,
354 /// Creates predicate obligations from the generic bounds.
355 pub fn predicates_for_generics<'tcx>(cause: ObligationCause<'tcx>,
356 generic_bounds: &ty::InstantiatedPredicates<'tcx>)
357 -> PredicateObligations<'tcx>
359 util::predicates_for_generics(cause, 0, generic_bounds)
362 /// Determines whether the type `ty` is known to meet `bound` and
363 /// returns true if so. Returns false if `ty` either does not meet
364 /// `bound` or is not known to meet bound (note that this is
365 /// conservative towards *no impl*, which is the opposite of the
366 /// `evaluate` methods).
367 pub fn type_known_to_meet_bound<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
373 debug!("type_known_to_meet_bound(ty={:?}, bound={:?})",
375 infcx.tcx.item_path_str(def_id));
377 let trait_ref = ty::TraitRef {
379 substs: infcx.tcx.mk_substs_trait(ty, &[]),
381 let obligation = Obligation {
382 cause: ObligationCause::misc(span, ast::DUMMY_NODE_ID),
384 predicate: trait_ref.to_predicate(),
387 let result = SelectionContext::new(infcx)
388 .evaluate_obligation_conservatively(&obligation);
389 debug!("type_known_to_meet_ty={:?} bound={} => {:?}",
390 ty, infcx.tcx.item_path_str(def_id), result);
392 if result && (ty.has_infer_types() || ty.has_closure_types()) {
393 // Because of inference "guessing", selection can sometimes claim
394 // to succeed while the success requires a guess. To ensure
395 // this function's result remains infallible, we must confirm
396 // that guess. While imperfect, I believe this is sound.
398 let mut fulfill_cx = FulfillmentContext::new();
400 // We can use a dummy node-id here because we won't pay any mind
401 // to region obligations that arise (there shouldn't really be any
403 let cause = ObligationCause::misc(span, ast::DUMMY_NODE_ID);
405 fulfill_cx.register_bound(infcx, ty, def_id, cause);
407 // Note: we only assume something is `Copy` if we can
408 // *definitively* show that it implements `Copy`. Otherwise,
409 // assume it is move; linear is always ok.
410 match fulfill_cx.select_all_or_error(infcx) {
412 debug!("type_known_to_meet_bound: ty={:?} bound={} success",
414 infcx.tcx.item_path_str(def_id));
418 debug!("type_known_to_meet_bound: ty={:?} bound={} errors={:?}",
420 infcx.tcx.item_path_str(def_id),
430 // FIXME: this is gonna need to be removed ...
431 /// Normalizes the parameter environment, reporting errors if they occur.
432 pub fn normalize_param_env_or_error<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
433 unnormalized_env: ty::ParameterEnvironment<'tcx>,
434 cause: ObligationCause<'tcx>)
435 -> ty::ParameterEnvironment<'tcx>
437 // I'm not wild about reporting errors here; I'd prefer to
438 // have the errors get reported at a defined place (e.g.,
439 // during typeck). Instead I have all parameter
440 // environments, in effect, going through this function
441 // and hence potentially reporting errors. This ensurse of
442 // course that we never forget to normalize (the
443 // alternative seemed like it would involve a lot of
444 // manual invocations of this fn -- and then we'd have to
445 // deal with the errors at each of those sites).
447 // In any case, in practice, typeck constructs all the
448 // parameter environments once for every fn as it goes,
449 // and errors will get reported then; so after typeck we
450 // can be sure that no errors should occur.
452 let span = cause.span;
453 let body_id = cause.body_id;
455 debug!("normalize_param_env_or_error(unnormalized_env={:?})",
458 let predicates: Vec<_> =
459 util::elaborate_predicates(tcx, unnormalized_env.caller_bounds.clone())
460 .filter(|p| !p.is_global()) // (*)
463 // (*) Any predicate like `i32: Trait<u32>` or whatever doesn't
464 // need to be in the *environment* to be proven, so screen those
465 // out. This is important for the soundness of inter-fn
466 // caching. Note though that we should probably check that these
467 // predicates hold at the point where the environment is
468 // constructed, but I am not currently doing so out of laziness.
471 debug!("normalize_param_env_or_error: elaborated-predicates={:?}",
474 let elaborated_env = unnormalized_env.with_caller_bounds(predicates);
476 tcx.infer_ctxt(elaborated_env, Reveal::UserFacing).enter(|infcx| {
477 let predicates = match fully_normalize(&infcx, cause,
478 &infcx.parameter_environment.caller_bounds) {
479 Ok(predicates) => predicates,
481 infcx.report_fulfillment_errors(&errors);
482 // An unnormalized env is better than nothing.
483 return infcx.parameter_environment;
487 debug!("normalize_param_env_or_error: normalized predicates={:?}",
490 let free_regions = FreeRegionMap::new();
491 infcx.resolve_regions_and_report_errors(&free_regions, body_id);
492 let predicates = match infcx.fully_resolve(&predicates) {
493 Ok(predicates) => predicates,
495 // If we encounter a fixup error, it means that some type
496 // variable wound up unconstrained. I actually don't know
497 // if this can happen, and I certainly don't expect it to
498 // happen often, but if it did happen it probably
499 // represents a legitimate failure due to some kind of
500 // unconstrained variable, and it seems better not to ICE,
501 // all things considered.
502 tcx.sess.span_err(span, &fixup_err.to_string());
503 // An unnormalized env is better than nothing.
504 return infcx.parameter_environment;
508 let predicates = match tcx.lift_to_global(&predicates) {
509 Some(predicates) => predicates,
510 None => return infcx.parameter_environment
513 debug!("normalize_param_env_or_error: resolved predicates={:?}",
516 infcx.parameter_environment.with_caller_bounds(predicates)
520 pub fn fully_normalize<'a, 'gcx, 'tcx, T>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
521 cause: ObligationCause<'tcx>,
523 -> Result<T, Vec<FulfillmentError<'tcx>>>
524 where T : TypeFoldable<'tcx>
526 debug!("fully_normalize(value={:?})", value);
528 let mut selcx = &mut SelectionContext::new(infcx);
529 // FIXME (@jroesch) ISSUE 26721
530 // I'm not sure if this is a bug or not, needs further investigation.
531 // It appears that by reusing the fulfillment_cx here we incur more
532 // obligations and later trip an asssertion on regionck.rs line 337.
534 // The two possibilities I see is:
535 // - normalization is not actually fully happening and we
536 // have a bug else where
537 // - we are adding a duplicate bound into the list causing
538 // its size to change.
540 // I think we should probably land this refactor and then come
541 // back to this is a follow-up patch.
542 let mut fulfill_cx = FulfillmentContext::new();
544 let Normalized { value: normalized_value, obligations } =
545 project::normalize(selcx, cause, value);
546 debug!("fully_normalize: normalized_value={:?} obligations={:?}",
549 for obligation in obligations {
550 fulfill_cx.register_predicate_obligation(selcx.infcx(), obligation);
553 debug!("fully_normalize: select_all_or_error start");
554 match fulfill_cx.select_all_or_error(infcx) {
557 debug!("fully_normalize: error={:?}", e);
561 debug!("fully_normalize: select_all_or_error complete");
562 let resolved_value = infcx.resolve_type_vars_if_possible(&normalized_value);
563 debug!("fully_normalize: resolved_value={:?}", resolved_value);
567 /// Normalizes the predicates and checks whether they hold. If this
568 /// returns false, then either normalize encountered an error or one
569 /// of the predicates did not hold. Used when creating vtables to
570 /// check for unsatisfiable methods.
571 pub fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
572 predicates: Vec<ty::Predicate<'tcx>>)
575 debug!("normalize_and_test_predicates(predicates={:?})",
578 tcx.infer_ctxt((), Reveal::All).enter(|infcx| {
579 let mut selcx = SelectionContext::new(&infcx);
580 let mut fulfill_cx = FulfillmentContext::new();
581 let cause = ObligationCause::dummy();
582 let Normalized { value: predicates, obligations } =
583 normalize(&mut selcx, cause.clone(), &predicates);
584 for obligation in obligations {
585 fulfill_cx.register_predicate_obligation(&infcx, obligation);
587 for predicate in predicates {
588 let obligation = Obligation::new(cause.clone(), predicate);
589 fulfill_cx.register_predicate_obligation(&infcx, obligation);
592 fulfill_cx.select_all_or_error(&infcx).is_ok()
596 /// Given a trait `trait_ref`, iterates the vtable entries
597 /// that come from `trait_ref`, including its supertraits.
598 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
599 pub fn get_vtable_methods<'a, 'tcx>(
600 tcx: TyCtxt<'a, 'tcx, 'tcx>,
601 trait_ref: ty::PolyTraitRef<'tcx>)
602 -> impl Iterator<Item=Option<(DefId, &'tcx Substs<'tcx>)>> + 'a
604 debug!("get_vtable_methods({:?})", trait_ref);
606 supertraits(tcx, trait_ref).flat_map(move |trait_ref| {
607 tcx.populate_implementations_for_trait_if_necessary(trait_ref.def_id());
609 let trait_methods = tcx.associated_items(trait_ref.def_id())
610 .filter(|item| item.kind == ty::AssociatedKind::Method);
612 // Now list each method's DefId and Substs (for within its trait).
613 // If the method can never be called from this object, produce None.
614 trait_methods.map(move |trait_method| {
615 debug!("get_vtable_methods: trait_method={:?}", trait_method);
616 let def_id = trait_method.def_id;
618 // Some methods cannot be called on an object; skip those.
619 if !tcx.is_vtable_safe_method(trait_ref.def_id(), &trait_method) {
620 debug!("get_vtable_methods: not vtable safe");
624 // the method may have some early-bound lifetimes, add
626 let substs = Substs::for_item(tcx, def_id,
627 |_, _| tcx.mk_region(ty::ReErased),
628 |def, _| trait_ref.substs().type_for_def(def));
630 // the trait type may have higher-ranked lifetimes in it;
631 // so erase them if they appear, so that we get the type
632 // at some particular call site
633 let substs = tcx.erase_late_bound_regions_and_normalize(&ty::Binder(substs));
635 // It's possible that the method relies on where clauses that
636 // do not hold for this particular set of type parameters.
637 // Note that this method could then never be called, so we
638 // do not want to try and trans it, in that case (see #23435).
639 let predicates = tcx.item_predicates(def_id).instantiate_own(tcx, substs);
640 if !normalize_and_test_predicates(tcx, predicates.predicates) {
641 debug!("get_vtable_methods: predicates do not hold");
645 Some((def_id, substs))
650 impl<'tcx,O> Obligation<'tcx,O> {
651 pub fn new(cause: ObligationCause<'tcx>,
653 -> Obligation<'tcx, O>
655 Obligation { cause: cause,
657 predicate: trait_ref }
660 fn with_depth(cause: ObligationCause<'tcx>,
661 recursion_depth: usize,
663 -> Obligation<'tcx, O>
665 Obligation { cause: cause,
666 recursion_depth: recursion_depth,
667 predicate: trait_ref }
670 pub fn misc(span: Span, body_id: ast::NodeId, trait_ref: O) -> Obligation<'tcx, O> {
671 Obligation::new(ObligationCause::misc(span, body_id), trait_ref)
674 pub fn with<P>(&self, value: P) -> Obligation<'tcx,P> {
675 Obligation { cause: self.cause.clone(),
676 recursion_depth: self.recursion_depth,
681 impl<'tcx> ObligationCause<'tcx> {
682 pub fn new(span: Span,
683 body_id: ast::NodeId,
684 code: ObligationCauseCode<'tcx>)
685 -> ObligationCause<'tcx> {
686 ObligationCause { span: span, body_id: body_id, code: code }
689 pub fn misc(span: Span, body_id: ast::NodeId) -> ObligationCause<'tcx> {
690 ObligationCause { span: span, body_id: body_id, code: MiscObligation }
693 pub fn dummy() -> ObligationCause<'tcx> {
694 ObligationCause { span: DUMMY_SP, body_id: ast::CRATE_NODE_ID, code: MiscObligation }
698 impl<'tcx, N> Vtable<'tcx, N> {
699 pub fn nested_obligations(self) -> Vec<N> {
701 VtableImpl(i) => i.nested,
703 VtableBuiltin(i) => i.nested,
704 VtableDefaultImpl(d) => d.nested,
705 VtableClosure(c) => c.nested,
706 VtableObject(d) => d.nested,
707 VtableFnPointer(d) => d.nested,
711 fn nested_obligations_mut(&mut self) -> &mut Vec<N> {
713 &mut VtableImpl(ref mut i) => &mut i.nested,
714 &mut VtableParam(ref mut n) => n,
715 &mut VtableBuiltin(ref mut i) => &mut i.nested,
716 &mut VtableDefaultImpl(ref mut d) => &mut d.nested,
717 &mut VtableClosure(ref mut c) => &mut c.nested,
718 &mut VtableObject(ref mut d) => &mut d.nested,
719 &mut VtableFnPointer(ref mut d) => &mut d.nested,
723 pub fn map<M, F>(self, f: F) -> Vtable<'tcx, M> where F: FnMut(N) -> M {
725 VtableImpl(i) => VtableImpl(VtableImplData {
726 impl_def_id: i.impl_def_id,
728 nested: i.nested.into_iter().map(f).collect(),
730 VtableParam(n) => VtableParam(n.into_iter().map(f).collect()),
731 VtableBuiltin(i) => VtableBuiltin(VtableBuiltinData {
732 nested: i.nested.into_iter().map(f).collect(),
734 VtableObject(o) => VtableObject(VtableObjectData {
735 upcast_trait_ref: o.upcast_trait_ref,
736 vtable_base: o.vtable_base,
737 nested: o.nested.into_iter().map(f).collect(),
739 VtableDefaultImpl(d) => VtableDefaultImpl(VtableDefaultImplData {
740 trait_def_id: d.trait_def_id,
741 nested: d.nested.into_iter().map(f).collect(),
743 VtableFnPointer(p) => VtableFnPointer(VtableFnPointerData {
745 nested: p.nested.into_iter().map(f).collect(),
747 VtableClosure(c) => VtableClosure(VtableClosureData {
748 closure_def_id: c.closure_def_id,
750 nested: c.nested.into_iter().map(f).collect(),
756 impl<'tcx> FulfillmentError<'tcx> {
757 fn new(obligation: PredicateObligation<'tcx>,
758 code: FulfillmentErrorCode<'tcx>)
759 -> FulfillmentError<'tcx>
761 FulfillmentError { obligation: obligation, code: code }
765 impl<'tcx> TraitObligation<'tcx> {
766 fn self_ty(&self) -> ty::Binder<Ty<'tcx>> {
767 ty::Binder(self.predicate.skip_binder().self_ty())