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::coherence::orphan_check;
32 pub use self::coherence::overlapping_impls;
33 pub use self::coherence::OrphanCheckErr;
34 pub use self::fulfill::{FulfillmentContext, GlobalFulfilledPredicates, RegionObligation};
35 pub use self::project::MismatchedProjectionTypes;
36 pub use self::project::{normalize, normalize_projection_type, Normalized};
37 pub use self::project::{ProjectionCache, ProjectionCacheSnapshot, Reveal};
38 pub use self::object_safety::ObjectSafetyViolation;
39 pub use self::object_safety::MethodViolationCode;
40 pub use self::select::{EvaluationCache, SelectionContext, SelectionCache};
41 pub use self::specialize::{OverlapError, specialization_graph, specializes, translate_substs};
42 pub use self::specialize::{SpecializesCache, find_associated_item};
43 pub use self::util::elaborate_predicates;
44 pub use self::util::supertraits;
45 pub use self::util::Supertraits;
46 pub use self::util::supertrait_def_ids;
47 pub use self::util::SupertraitDefIds;
48 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 param_env: ty::ParamEnv<'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 param_env: ty::ParamEnv<'tcx>,
363 generic_bounds: &ty::InstantiatedPredicates<'tcx>)
364 -> PredicateObligations<'tcx>
366 util::predicates_for_generics(cause, 0, param_env, generic_bounds)
369 /// Determines whether the type `ty` is known to meet `bound` and
370 /// returns true if so. Returns false if `ty` either does not meet
371 /// `bound` or is not known to meet bound (note that this is
372 /// conservative towards *no impl*, which is the opposite of the
373 /// `evaluate` methods).
374 pub fn type_known_to_meet_bound<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
375 param_env: ty::ParamEnv<'tcx>,
381 debug!("type_known_to_meet_bound(ty={:?}, bound={:?})",
383 infcx.tcx.item_path_str(def_id));
385 let trait_ref = ty::TraitRef {
387 substs: infcx.tcx.mk_substs_trait(ty, &[]),
389 let obligation = Obligation {
391 cause: ObligationCause::misc(span, ast::DUMMY_NODE_ID),
393 predicate: trait_ref.to_predicate(),
396 let result = SelectionContext::new(infcx)
397 .evaluate_obligation_conservatively(&obligation);
398 debug!("type_known_to_meet_ty={:?} bound={} => {:?}",
399 ty, infcx.tcx.item_path_str(def_id), result);
401 if result && (ty.has_infer_types() || ty.has_closure_types()) {
402 // Because of inference "guessing", selection can sometimes claim
403 // to succeed while the success requires a guess. To ensure
404 // this function's result remains infallible, we must confirm
405 // that guess. While imperfect, I believe this is sound.
407 let mut fulfill_cx = FulfillmentContext::new();
409 // We can use a dummy node-id here because we won't pay any mind
410 // to region obligations that arise (there shouldn't really be any
412 let cause = ObligationCause::misc(span, ast::DUMMY_NODE_ID);
414 fulfill_cx.register_bound(infcx, param_env, ty, def_id, cause);
416 // Note: we only assume something is `Copy` if we can
417 // *definitively* show that it implements `Copy`. Otherwise,
418 // assume it is move; linear is always ok.
419 match fulfill_cx.select_all_or_error(infcx) {
421 debug!("type_known_to_meet_bound: ty={:?} bound={} success",
423 infcx.tcx.item_path_str(def_id));
427 debug!("type_known_to_meet_bound: ty={:?} bound={} errors={:?}",
429 infcx.tcx.item_path_str(def_id),
439 // FIXME: this is gonna need to be removed ...
440 /// Normalizes the parameter environment, reporting errors if they occur.
441 pub fn normalize_param_env_or_error<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
442 region_context: DefId,
443 unnormalized_env: ty::ParamEnv<'tcx>,
444 cause: ObligationCause<'tcx>)
445 -> ty::ParamEnv<'tcx>
447 // I'm not wild about reporting errors here; I'd prefer to
448 // have the errors get reported at a defined place (e.g.,
449 // during typeck). Instead I have all parameter
450 // environments, in effect, going through this function
451 // and hence potentially reporting errors. This ensurse of
452 // course that we never forget to normalize (the
453 // alternative seemed like it would involve a lot of
454 // manual invocations of this fn -- and then we'd have to
455 // deal with the errors at each of those sites).
457 // In any case, in practice, typeck constructs all the
458 // parameter environments once for every fn as it goes,
459 // and errors will get reported then; so after typeck we
460 // can be sure that no errors should occur.
462 let span = cause.span;
464 debug!("normalize_param_env_or_error(unnormalized_env={:?})",
467 let predicates: Vec<_> =
468 util::elaborate_predicates(tcx, unnormalized_env.caller_bounds.to_vec())
469 .filter(|p| !p.is_global()) // (*)
472 // (*) Any predicate like `i32: Trait<u32>` or whatever doesn't
473 // need to be in the *environment* to be proven, so screen those
474 // out. This is important for the soundness of inter-fn
475 // caching. Note though that we should probably check that these
476 // predicates hold at the point where the environment is
477 // constructed, but I am not currently doing so out of laziness.
480 debug!("normalize_param_env_or_error: elaborated-predicates={:?}",
483 let elaborated_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates),
484 unnormalized_env.reveal);
486 tcx.infer_ctxt().enter(|infcx| {
487 let predicates = match fully_normalize(
491 // You would really want to pass infcx.param_env.caller_bounds here,
492 // but that is an interned slice, and fully_normalize takes &T and returns T, so
493 // without further refactoring, a slice can't be used. Luckily, we still have the
494 // predicate vector from which we created the ParamEnv in infcx, so we
495 // can pass that instead. It's roundabout and a bit brittle, but this code path
496 // ought to be refactored anyway, and until then it saves us from having to copy.
499 Ok(predicates) => predicates,
501 infcx.report_fulfillment_errors(&errors);
502 // An unnormalized env is better than nothing.
503 return elaborated_env;
507 debug!("normalize_param_env_or_error: normalized predicates={:?}",
510 let region_maps = RegionMaps::new();
511 let free_regions = FreeRegionMap::new();
512 infcx.resolve_regions_and_report_errors(region_context, ®ion_maps, &free_regions);
513 let predicates = match infcx.fully_resolve(&predicates) {
514 Ok(predicates) => predicates,
516 // If we encounter a fixup error, it means that some type
517 // variable wound up unconstrained. I actually don't know
518 // if this can happen, and I certainly don't expect it to
519 // happen often, but if it did happen it probably
520 // represents a legitimate failure due to some kind of
521 // unconstrained variable, and it seems better not to ICE,
522 // all things considered.
523 tcx.sess.span_err(span, &fixup_err.to_string());
524 // An unnormalized env is better than nothing.
525 return elaborated_env;
529 let predicates = match tcx.lift_to_global(&predicates) {
530 Some(predicates) => predicates,
531 None => return elaborated_env,
534 debug!("normalize_param_env_or_error: resolved predicates={:?}",
537 ty::ParamEnv::new(tcx.intern_predicates(&predicates), unnormalized_env.reveal)
541 pub fn fully_normalize<'a, 'gcx, 'tcx, T>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
542 cause: ObligationCause<'tcx>,
543 param_env: ty::ParamEnv<'tcx>,
545 -> Result<T, Vec<FulfillmentError<'tcx>>>
546 where T : TypeFoldable<'tcx>
548 debug!("fully_normalize(value={:?})", value);
550 let mut selcx = &mut SelectionContext::new(infcx);
551 // FIXME (@jroesch) ISSUE 26721
552 // I'm not sure if this is a bug or not, needs further investigation.
553 // It appears that by reusing the fulfillment_cx here we incur more
554 // obligations and later trip an asssertion on regionck.rs line 337.
556 // The two possibilities I see is:
557 // - normalization is not actually fully happening and we
558 // have a bug else where
559 // - we are adding a duplicate bound into the list causing
560 // its size to change.
562 // I think we should probably land this refactor and then come
563 // back to this is a follow-up patch.
564 let mut fulfill_cx = FulfillmentContext::new();
566 let Normalized { value: normalized_value, obligations } =
567 project::normalize(selcx, param_env, cause, value);
568 debug!("fully_normalize: normalized_value={:?} obligations={:?}",
571 for obligation in obligations {
572 fulfill_cx.register_predicate_obligation(selcx.infcx(), obligation);
575 debug!("fully_normalize: select_all_or_error start");
576 match fulfill_cx.select_all_or_error(infcx) {
579 debug!("fully_normalize: error={:?}", e);
583 debug!("fully_normalize: select_all_or_error complete");
584 let resolved_value = infcx.resolve_type_vars_if_possible(&normalized_value);
585 debug!("fully_normalize: resolved_value={:?}", resolved_value);
589 /// Normalizes the predicates and checks whether they hold in an empty
590 /// environment. If this returns false, then either normalize
591 /// encountered an error or one of the predicates did not hold. Used
592 /// when creating vtables to check for unsatisfiable methods.
593 pub fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
594 predicates: Vec<ty::Predicate<'tcx>>)
597 debug!("normalize_and_test_predicates(predicates={:?})",
600 let result = tcx.infer_ctxt().enter(|infcx| {
601 let param_env = ty::ParamEnv::empty(Reveal::All);
602 let mut selcx = SelectionContext::new(&infcx);
603 let mut fulfill_cx = FulfillmentContext::new();
604 let cause = ObligationCause::dummy();
605 let Normalized { value: predicates, obligations } =
606 normalize(&mut selcx, param_env, cause.clone(), &predicates);
607 for obligation in obligations {
608 fulfill_cx.register_predicate_obligation(&infcx, obligation);
610 for predicate in predicates {
611 let obligation = Obligation::new(cause.clone(), param_env, predicate);
612 fulfill_cx.register_predicate_obligation(&infcx, obligation);
615 fulfill_cx.select_all_or_error(&infcx).is_ok()
617 debug!("normalize_and_test_predicates(predicates={:?}) = {:?}",
622 /// Given a trait `trait_ref`, iterates the vtable entries
623 /// that come from `trait_ref`, including its supertraits.
624 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
625 pub fn get_vtable_methods<'a, 'tcx>(
626 tcx: TyCtxt<'a, 'tcx, 'tcx>,
627 trait_ref: ty::PolyTraitRef<'tcx>)
628 -> impl Iterator<Item=Option<(DefId, &'tcx Substs<'tcx>)>> + 'a
630 debug!("get_vtable_methods({:?})", trait_ref);
632 supertraits(tcx, trait_ref).flat_map(move |trait_ref| {
633 let trait_methods = tcx.associated_items(trait_ref.def_id())
634 .filter(|item| item.kind == ty::AssociatedKind::Method);
636 // Now list each method's DefId and Substs (for within its trait).
637 // If the method can never be called from this object, produce None.
638 trait_methods.map(move |trait_method| {
639 debug!("get_vtable_methods: trait_method={:?}", trait_method);
640 let def_id = trait_method.def_id;
642 // Some methods cannot be called on an object; skip those.
643 if !tcx.is_vtable_safe_method(trait_ref.def_id(), &trait_method) {
644 debug!("get_vtable_methods: not vtable safe");
648 // the method may have some early-bound lifetimes, add
650 let substs = Substs::for_item(tcx, def_id,
651 |_, _| tcx.types.re_erased,
652 |def, _| trait_ref.substs().type_for_def(def));
654 // the trait type may have higher-ranked lifetimes in it;
655 // so erase them if they appear, so that we get the type
656 // at some particular call site
657 let substs = tcx.erase_late_bound_regions_and_normalize(&ty::Binder(substs));
659 // It's possible that the method relies on where clauses that
660 // do not hold for this particular set of type parameters.
661 // Note that this method could then never be called, so we
662 // do not want to try and trans it, in that case (see #23435).
663 let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
664 if !normalize_and_test_predicates(tcx, predicates.predicates) {
665 debug!("get_vtable_methods: predicates do not hold");
669 Some((def_id, substs))
674 impl<'tcx,O> Obligation<'tcx,O> {
675 pub fn new(cause: ObligationCause<'tcx>,
676 param_env: ty::ParamEnv<'tcx>,
678 -> Obligation<'tcx, O>
680 Obligation { cause, param_env, recursion_depth: 0, predicate }
683 fn with_depth(cause: ObligationCause<'tcx>,
684 recursion_depth: usize,
685 param_env: ty::ParamEnv<'tcx>,
687 -> Obligation<'tcx, O>
689 Obligation { cause, param_env, recursion_depth, predicate }
692 pub fn misc(span: Span,
693 body_id: ast::NodeId,
694 param_env: ty::ParamEnv<'tcx>,
696 -> Obligation<'tcx, O> {
697 Obligation::new(ObligationCause::misc(span, body_id), param_env, trait_ref)
700 pub fn with<P>(&self, value: P) -> Obligation<'tcx,P> {
701 Obligation { cause: self.cause.clone(),
702 param_env: self.param_env,
703 recursion_depth: self.recursion_depth,
708 impl<'tcx> ObligationCause<'tcx> {
709 pub fn new(span: Span,
710 body_id: ast::NodeId,
711 code: ObligationCauseCode<'tcx>)
712 -> ObligationCause<'tcx> {
713 ObligationCause { span: span, body_id: body_id, code: code }
716 pub fn misc(span: Span, body_id: ast::NodeId) -> ObligationCause<'tcx> {
717 ObligationCause { span: span, body_id: body_id, code: MiscObligation }
720 pub fn dummy() -> ObligationCause<'tcx> {
721 ObligationCause { span: DUMMY_SP, body_id: ast::CRATE_NODE_ID, code: MiscObligation }
725 impl<'tcx, N> Vtable<'tcx, N> {
726 pub fn nested_obligations(self) -> Vec<N> {
728 VtableImpl(i) => i.nested,
730 VtableBuiltin(i) => i.nested,
731 VtableDefaultImpl(d) => d.nested,
732 VtableClosure(c) => c.nested,
733 VtableObject(d) => d.nested,
734 VtableFnPointer(d) => d.nested,
738 fn nested_obligations_mut(&mut self) -> &mut Vec<N> {
740 &mut VtableImpl(ref mut i) => &mut i.nested,
741 &mut VtableParam(ref mut n) => n,
742 &mut VtableBuiltin(ref mut i) => &mut i.nested,
743 &mut VtableDefaultImpl(ref mut d) => &mut d.nested,
744 &mut VtableClosure(ref mut c) => &mut c.nested,
745 &mut VtableObject(ref mut d) => &mut d.nested,
746 &mut VtableFnPointer(ref mut d) => &mut d.nested,
750 pub fn map<M, F>(self, f: F) -> Vtable<'tcx, M> where F: FnMut(N) -> M {
752 VtableImpl(i) => VtableImpl(VtableImplData {
753 impl_def_id: i.impl_def_id,
755 nested: i.nested.into_iter().map(f).collect(),
757 VtableParam(n) => VtableParam(n.into_iter().map(f).collect()),
758 VtableBuiltin(i) => VtableBuiltin(VtableBuiltinData {
759 nested: i.nested.into_iter().map(f).collect(),
761 VtableObject(o) => VtableObject(VtableObjectData {
762 upcast_trait_ref: o.upcast_trait_ref,
763 vtable_base: o.vtable_base,
764 nested: o.nested.into_iter().map(f).collect(),
766 VtableDefaultImpl(d) => VtableDefaultImpl(VtableDefaultImplData {
767 trait_def_id: d.trait_def_id,
768 nested: d.nested.into_iter().map(f).collect(),
770 VtableFnPointer(p) => VtableFnPointer(VtableFnPointerData {
772 nested: p.nested.into_iter().map(f).collect(),
774 VtableClosure(c) => VtableClosure(VtableClosureData {
775 closure_def_id: c.closure_def_id,
777 nested: c.nested.into_iter().map(f).collect(),
783 impl<'tcx> FulfillmentError<'tcx> {
784 fn new(obligation: PredicateObligation<'tcx>,
785 code: FulfillmentErrorCode<'tcx>)
786 -> FulfillmentError<'tcx>
788 FulfillmentError { obligation: obligation, code: code }
792 impl<'tcx> TraitObligation<'tcx> {
793 fn self_ty(&self) -> ty::Binder<Ty<'tcx>> {
794 ty::Binder(self.predicate.skip_binder().self_ty())
798 pub fn provide(providers: &mut ty::maps::Providers) {
799 *providers = ty::maps::Providers {
800 is_object_safe: object_safety::is_object_safe_provider,
801 specialization_graph_of: specialize::specialization_graph_provider,
806 pub fn provide_extern(providers: &mut ty::maps::Providers) {
807 *providers = ty::maps::Providers {
808 is_object_safe: object_safety::is_object_safe_provider,
809 specialization_graph_of: specialize::specialization_graph_provider,