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 param_env: ty::ParamEnv<'tcx>,
72 pub recursion_depth: usize,
76 pub type PredicateObligation<'tcx> = Obligation<'tcx, ty::Predicate<'tcx>>;
77 pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
79 /// Why did we incur this obligation? Used for error reporting.
80 #[derive(Clone, Debug, PartialEq, Eq)]
81 pub struct ObligationCause<'tcx> {
84 // The id of the fn body that triggered this obligation. This is
85 // used for region obligations to determine the precise
86 // environment in which the region obligation should be evaluated
87 // (in particular, closures can add new assumptions). See the
88 // field `region_obligations` of the `FulfillmentContext` for more
90 pub body_id: ast::NodeId,
92 pub code: ObligationCauseCode<'tcx>
95 #[derive(Clone, Debug, PartialEq, Eq)]
96 pub enum ObligationCauseCode<'tcx> {
97 /// Not well classified or should be obvious from span.
100 /// A slice or array is WF only if `T: Sized`
103 /// A tuple is WF only if its middle elements are Sized
106 /// This is the trait reference from the given projection
107 ProjectionWf(ty::ProjectionTy<'tcx>),
109 /// In an impl of trait X for type Y, type Y must
110 /// also implement all supertraits of X.
111 ItemObligation(DefId),
113 /// A type like `&'a T` is WF only if `T: 'a`.
114 ReferenceOutlivesReferent(Ty<'tcx>),
116 /// A type like `Box<Foo<'a> + 'b>` is WF only if `'b: 'a`.
117 ObjectTypeBound(Ty<'tcx>, ty::Region<'tcx>),
119 /// Obligation incurred due to an object cast.
120 ObjectCastObligation(/* Object type */ Ty<'tcx>),
122 /// Various cases where expressions must be sized/copy/etc:
123 AssignmentLhsSized, // L = X implies that L is Sized
124 StructInitializerSized, // S { ... } must be Sized
125 VariableType(ast::NodeId), // Type of each variable must be Sized
126 ReturnType, // Return type must be Sized
127 RepeatVec, // [T,..n] --> T must be Copy
129 // Types of fields (other than the last) in a struct must be sized.
132 // Constant expressions must be sized.
135 // static items must have `Sync` type
138 BuiltinDerivedObligation(DerivedObligationCause<'tcx>),
140 ImplDerivedObligation(DerivedObligationCause<'tcx>),
142 // error derived when matching traits/impls; see ObligationCause for more details
143 CompareImplMethodObligation {
144 item_name: ast::Name,
145 impl_item_def_id: DefId,
146 trait_item_def_id: DefId,
147 lint_id: Option<ast::NodeId>,
150 // Checking that this expression can be assigned where it needs to be
151 // FIXME(eddyb) #11161 is the original Expr required?
154 // Computing common supertype in the arms of a match expression
155 MatchExpressionArm { arm_span: Span,
156 source: hir::MatchSource },
158 // Computing common supertype in an if expression
161 // Computing common supertype of an if expression with no else counter-part
162 IfExpressionWithNoElse,
167 // `main` has wrong type
170 // `start` has wrong type
173 // intrinsic has wrong type
179 // `return` with no expression
183 #[derive(Clone, Debug, PartialEq, Eq)]
184 pub struct DerivedObligationCause<'tcx> {
185 /// The trait reference of the parent obligation that led to the
186 /// current obligation. Note that only trait obligations lead to
187 /// derived obligations, so we just store the trait reference here
189 parent_trait_ref: ty::PolyTraitRef<'tcx>,
191 /// The parent trait had this cause
192 parent_code: Rc<ObligationCauseCode<'tcx>>
195 pub type Obligations<'tcx, O> = Vec<Obligation<'tcx, O>>;
196 pub type PredicateObligations<'tcx> = Vec<PredicateObligation<'tcx>>;
197 pub type TraitObligations<'tcx> = Vec<TraitObligation<'tcx>>;
199 pub type Selection<'tcx> = Vtable<'tcx, PredicateObligation<'tcx>>;
201 #[derive(Clone,Debug)]
202 pub enum SelectionError<'tcx> {
204 OutputTypeParameterMismatch(ty::PolyTraitRef<'tcx>,
205 ty::PolyTraitRef<'tcx>,
206 ty::error::TypeError<'tcx>),
207 TraitNotObjectSafe(DefId),
210 pub struct FulfillmentError<'tcx> {
211 pub obligation: PredicateObligation<'tcx>,
212 pub code: FulfillmentErrorCode<'tcx>
216 pub enum FulfillmentErrorCode<'tcx> {
217 CodeSelectionError(SelectionError<'tcx>),
218 CodeProjectionError(MismatchedProjectionTypes<'tcx>),
219 CodeSubtypeError(ExpectedFound<Ty<'tcx>>,
220 TypeError<'tcx>), // always comes from a SubtypePredicate
224 /// When performing resolution, it is typically the case that there
225 /// can be one of three outcomes:
227 /// - `Ok(Some(r))`: success occurred with result `r`
228 /// - `Ok(None)`: could not definitely determine anything, usually due
229 /// to inconclusive type inference.
230 /// - `Err(e)`: error `e` occurred
231 pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>;
233 /// Given the successful resolution of an obligation, the `Vtable`
234 /// indicates where the vtable comes from. Note that while we call this
235 /// a "vtable", it does not necessarily indicate dynamic dispatch at
236 /// runtime. `Vtable` instances just tell the compiler where to find
237 /// methods, but in generic code those methods are typically statically
238 /// dispatched -- only when an object is constructed is a `Vtable`
239 /// instance reified into an actual vtable.
241 /// For example, the vtable may be tied to a specific impl (case A),
242 /// or it may be relative to some bound that is in scope (case B).
246 /// impl<T:Clone> Clone<T> for Option<T> { ... } // Impl_1
247 /// impl<T:Clone> Clone<T> for Box<T> { ... } // Impl_2
248 /// impl Clone for int { ... } // Impl_3
250 /// fn foo<T:Clone>(concrete: Option<Box<int>>,
252 /// mixed: Option<T>) {
254 /// // Case A: Vtable points at a specific impl. Only possible when
255 /// // type is concretely known. If the impl itself has bounded
256 /// // type parameters, Vtable will carry resolutions for those as well:
257 /// concrete.clone(); // Vtable(Impl_1, [Vtable(Impl_2, [Vtable(Impl_3)])])
259 /// // Case B: Vtable must be provided by caller. This applies when
260 /// // type is a type parameter.
261 /// param.clone(); // VtableParam
263 /// // Case C: A mix of cases A and B.
264 /// mixed.clone(); // Vtable(Impl_1, [VtableParam])
268 /// ### The type parameter `N`
270 /// See explanation on `VtableImplData`.
272 pub enum Vtable<'tcx, N> {
273 /// Vtable identifying a particular impl.
274 VtableImpl(VtableImplData<'tcx, N>),
276 /// Vtable for default trait implementations
277 /// This carries the information and nested obligations with regards
278 /// to a default implementation for a trait `Trait`. The nested obligations
279 /// ensure the trait implementation holds for all the constituent types.
280 VtableDefaultImpl(VtableDefaultImplData<N>),
282 /// Successful resolution to an obligation provided by the caller
283 /// for some type parameter. The `Vec<N>` represents the
284 /// obligations incurred from normalizing the where-clause (if
288 /// Virtual calls through an object
289 VtableObject(VtableObjectData<'tcx, N>),
291 /// Successful resolution for a builtin trait.
292 VtableBuiltin(VtableBuiltinData<N>),
294 /// Vtable automatically generated for a closure. The def ID is the ID
295 /// of the closure expression. This is a `VtableImpl` in spirit, but the
296 /// impl is generated by the compiler and does not appear in the source.
297 VtableClosure(VtableClosureData<'tcx, N>),
299 /// Same as above, but for a fn pointer type with the given signature.
300 VtableFnPointer(VtableFnPointerData<'tcx, N>),
303 /// Identifies a particular impl in the source, along with a set of
304 /// substitutions from the impl's type/lifetime parameters. The
305 /// `nested` vector corresponds to the nested obligations attached to
306 /// the impl's type parameters.
308 /// The type parameter `N` indicates the type used for "nested
309 /// obligations" that are required by the impl. During type check, this
310 /// is `Obligation`, as one might expect. During trans, however, this
311 /// is `()`, because trans only requires a shallow resolution of an
312 /// impl, and nested obligations are satisfied later.
313 #[derive(Clone, PartialEq, Eq)]
314 pub struct VtableImplData<'tcx, N> {
315 pub impl_def_id: DefId,
316 pub substs: &'tcx Substs<'tcx>,
320 #[derive(Clone, PartialEq, Eq)]
321 pub struct VtableClosureData<'tcx, N> {
322 pub closure_def_id: DefId,
323 pub substs: ty::ClosureSubsts<'tcx>,
324 /// Nested obligations. This can be non-empty if the closure
325 /// signature contains associated types.
330 pub struct VtableDefaultImplData<N> {
331 pub trait_def_id: DefId,
336 pub struct VtableBuiltinData<N> {
340 /// A vtable for some object-safe trait `Foo` automatically derived
341 /// for the object type `Foo`.
342 #[derive(PartialEq,Eq,Clone)]
343 pub struct VtableObjectData<'tcx, N> {
344 /// `Foo` upcast to the obligation trait. This will be some supertrait of `Foo`.
345 pub upcast_trait_ref: ty::PolyTraitRef<'tcx>,
347 /// The vtable is formed by concatenating together the method lists of
348 /// the base object trait and all supertraits; this is the start of
349 /// `upcast_trait_ref`'s methods in that vtable.
350 pub vtable_base: usize,
355 #[derive(Clone, PartialEq, Eq)]
356 pub struct VtableFnPointerData<'tcx, N> {
357 pub fn_ty: ty::Ty<'tcx>,
361 /// Creates predicate obligations from the generic bounds.
362 pub fn predicates_for_generics<'tcx>(cause: ObligationCause<'tcx>,
363 param_env: ty::ParamEnv<'tcx>,
364 generic_bounds: &ty::InstantiatedPredicates<'tcx>)
365 -> PredicateObligations<'tcx>
367 util::predicates_for_generics(cause, 0, param_env, generic_bounds)
370 /// Determines whether the type `ty` is known to meet `bound` and
371 /// returns true if so. Returns false if `ty` either does not meet
372 /// `bound` or is not known to meet bound (note that this is
373 /// conservative towards *no impl*, which is the opposite of the
374 /// `evaluate` methods).
375 pub fn type_known_to_meet_bound<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
376 param_env: ty::ParamEnv<'tcx>,
382 debug!("type_known_to_meet_bound(ty={:?}, bound={:?})",
384 infcx.tcx.item_path_str(def_id));
386 let trait_ref = ty::TraitRef {
388 substs: infcx.tcx.mk_substs_trait(ty, &[]),
390 let obligation = Obligation {
392 cause: ObligationCause::misc(span, ast::DUMMY_NODE_ID),
394 predicate: trait_ref.to_predicate(),
397 let result = SelectionContext::new(infcx)
398 .evaluate_obligation_conservatively(&obligation);
399 debug!("type_known_to_meet_ty={:?} bound={} => {:?}",
400 ty, infcx.tcx.item_path_str(def_id), result);
402 if result && (ty.has_infer_types() || ty.has_closure_types()) {
403 // Because of inference "guessing", selection can sometimes claim
404 // to succeed while the success requires a guess. To ensure
405 // this function's result remains infallible, we must confirm
406 // that guess. While imperfect, I believe this is sound.
408 let mut fulfill_cx = FulfillmentContext::new();
410 // We can use a dummy node-id here because we won't pay any mind
411 // to region obligations that arise (there shouldn't really be any
413 let cause = ObligationCause::misc(span, ast::DUMMY_NODE_ID);
415 fulfill_cx.register_bound(infcx, param_env, ty, def_id, cause);
417 // Note: we only assume something is `Copy` if we can
418 // *definitively* show that it implements `Copy`. Otherwise,
419 // assume it is move; linear is always ok.
420 match fulfill_cx.select_all_or_error(infcx) {
422 debug!("type_known_to_meet_bound: ty={:?} bound={} success",
424 infcx.tcx.item_path_str(def_id));
428 debug!("type_known_to_meet_bound: ty={:?} bound={} errors={:?}",
430 infcx.tcx.item_path_str(def_id),
440 // FIXME: this is gonna need to be removed ...
441 /// Normalizes the parameter environment, reporting errors if they occur.
442 pub fn normalize_param_env_or_error<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
443 region_context: DefId,
444 unnormalized_env: ty::ParamEnv<'tcx>,
445 cause: ObligationCause<'tcx>)
446 -> ty::ParamEnv<'tcx>
448 // I'm not wild about reporting errors here; I'd prefer to
449 // have the errors get reported at a defined place (e.g.,
450 // during typeck). Instead I have all parameter
451 // environments, in effect, going through this function
452 // and hence potentially reporting errors. This ensurse of
453 // course that we never forget to normalize (the
454 // alternative seemed like it would involve a lot of
455 // manual invocations of this fn -- and then we'd have to
456 // deal with the errors at each of those sites).
458 // In any case, in practice, typeck constructs all the
459 // parameter environments once for every fn as it goes,
460 // and errors will get reported then; so after typeck we
461 // can be sure that no errors should occur.
463 let span = cause.span;
465 debug!("normalize_param_env_or_error(unnormalized_env={:?})",
468 let predicates: Vec<_> =
469 util::elaborate_predicates(tcx, unnormalized_env.caller_bounds.to_vec())
470 .filter(|p| !p.is_global()) // (*)
473 // (*) Any predicate like `i32: Trait<u32>` or whatever doesn't
474 // need to be in the *environment* to be proven, so screen those
475 // out. This is important for the soundness of inter-fn
476 // caching. Note though that we should probably check that these
477 // predicates hold at the point where the environment is
478 // constructed, but I am not currently doing so out of laziness.
481 debug!("normalize_param_env_or_error: elaborated-predicates={:?}",
484 let elaborated_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates),
485 unnormalized_env.reveal);
487 tcx.infer_ctxt(()).enter(|infcx| {
488 let predicates = match fully_normalize(
492 // You would really want to pass infcx.param_env.caller_bounds here,
493 // but that is an interned slice, and fully_normalize takes &T and returns T, so
494 // without further refactoring, a slice can't be used. Luckily, we still have the
495 // predicate vector from which we created the ParamEnv in infcx, so we
496 // can pass that instead. It's roundabout and a bit brittle, but this code path
497 // ought to be refactored anyway, and until then it saves us from having to copy.
500 Ok(predicates) => predicates,
502 infcx.report_fulfillment_errors(&errors);
503 // An unnormalized env is better than nothing.
504 return elaborated_env;
508 debug!("normalize_param_env_or_error: normalized predicates={:?}",
511 let region_maps = RegionMaps::new();
512 let free_regions = FreeRegionMap::new();
513 infcx.resolve_regions_and_report_errors(region_context, ®ion_maps, &free_regions);
514 let predicates = match infcx.fully_resolve(&predicates) {
515 Ok(predicates) => predicates,
517 // If we encounter a fixup error, it means that some type
518 // variable wound up unconstrained. I actually don't know
519 // if this can happen, and I certainly don't expect it to
520 // happen often, but if it did happen it probably
521 // represents a legitimate failure due to some kind of
522 // unconstrained variable, and it seems better not to ICE,
523 // all things considered.
524 tcx.sess.span_err(span, &fixup_err.to_string());
525 // An unnormalized env is better than nothing.
526 return elaborated_env;
530 let predicates = match tcx.lift_to_global(&predicates) {
531 Some(predicates) => predicates,
532 None => return elaborated_env,
535 debug!("normalize_param_env_or_error: resolved predicates={:?}",
538 ty::ParamEnv::new(tcx.intern_predicates(&predicates), unnormalized_env.reveal)
542 pub fn fully_normalize<'a, 'gcx, 'tcx, T>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
543 cause: ObligationCause<'tcx>,
544 param_env: ty::ParamEnv<'tcx>,
546 -> Result<T, Vec<FulfillmentError<'tcx>>>
547 where T : TypeFoldable<'tcx>
549 debug!("fully_normalize(value={:?})", value);
551 let mut selcx = &mut SelectionContext::new(infcx);
552 // FIXME (@jroesch) ISSUE 26721
553 // I'm not sure if this is a bug or not, needs further investigation.
554 // It appears that by reusing the fulfillment_cx here we incur more
555 // obligations and later trip an asssertion on regionck.rs line 337.
557 // The two possibilities I see is:
558 // - normalization is not actually fully happening and we
559 // have a bug else where
560 // - we are adding a duplicate bound into the list causing
561 // its size to change.
563 // I think we should probably land this refactor and then come
564 // back to this is a follow-up patch.
565 let mut fulfill_cx = FulfillmentContext::new();
567 let Normalized { value: normalized_value, obligations } =
568 project::normalize(selcx, param_env, cause, value);
569 debug!("fully_normalize: normalized_value={:?} obligations={:?}",
572 for obligation in obligations {
573 fulfill_cx.register_predicate_obligation(selcx.infcx(), obligation);
576 debug!("fully_normalize: select_all_or_error start");
577 match fulfill_cx.select_all_or_error(infcx) {
580 debug!("fully_normalize: error={:?}", e);
584 debug!("fully_normalize: select_all_or_error complete");
585 let resolved_value = infcx.resolve_type_vars_if_possible(&normalized_value);
586 debug!("fully_normalize: resolved_value={:?}", resolved_value);
590 /// Normalizes the predicates and checks whether they hold in an empty
591 /// environment. If this returns false, then either normalize
592 /// encountered an error or one of the predicates did not hold. Used
593 /// when creating vtables to check for unsatisfiable methods.
594 pub fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
595 predicates: Vec<ty::Predicate<'tcx>>)
598 debug!("normalize_and_test_predicates(predicates={:?})",
601 tcx.infer_ctxt(()).enter(|infcx| {
602 let param_env = ty::ParamEnv::empty(Reveal::All);
603 let mut selcx = SelectionContext::new(&infcx);
604 let mut fulfill_cx = FulfillmentContext::new();
605 let cause = ObligationCause::dummy();
606 let Normalized { value: predicates, obligations } =
607 normalize(&mut selcx, param_env, cause.clone(), &predicates);
608 for obligation in obligations {
609 fulfill_cx.register_predicate_obligation(&infcx, obligation);
611 for predicate in predicates {
612 let obligation = Obligation::new(cause.clone(), param_env, predicate);
613 fulfill_cx.register_predicate_obligation(&infcx, obligation);
616 fulfill_cx.select_all_or_error(&infcx).is_ok()
620 /// Given a trait `trait_ref`, iterates the vtable entries
621 /// that come from `trait_ref`, including its supertraits.
622 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
623 pub fn get_vtable_methods<'a, 'tcx>(
624 tcx: TyCtxt<'a, 'tcx, 'tcx>,
625 trait_ref: ty::PolyTraitRef<'tcx>)
626 -> impl Iterator<Item=Option<(DefId, &'tcx Substs<'tcx>)>> + 'a
628 debug!("get_vtable_methods({:?})", trait_ref);
630 supertraits(tcx, trait_ref).flat_map(move |trait_ref| {
631 let trait_methods = tcx.associated_items(trait_ref.def_id())
632 .filter(|item| item.kind == ty::AssociatedKind::Method);
634 // Now list each method's DefId and Substs (for within its trait).
635 // If the method can never be called from this object, produce None.
636 trait_methods.map(move |trait_method| {
637 debug!("get_vtable_methods: trait_method={:?}", trait_method);
638 let def_id = trait_method.def_id;
640 // Some methods cannot be called on an object; skip those.
641 if !tcx.is_vtable_safe_method(trait_ref.def_id(), &trait_method) {
642 debug!("get_vtable_methods: not vtable safe");
646 // the method may have some early-bound lifetimes, add
648 let substs = Substs::for_item(tcx, def_id,
649 |_, _| tcx.types.re_erased,
650 |def, _| trait_ref.substs().type_for_def(def));
652 // the trait type may have higher-ranked lifetimes in it;
653 // so erase them if they appear, so that we get the type
654 // at some particular call site
655 let substs = tcx.erase_late_bound_regions_and_normalize(&ty::Binder(substs));
657 // It's possible that the method relies on where clauses that
658 // do not hold for this particular set of type parameters.
659 // Note that this method could then never be called, so we
660 // do not want to try and trans it, in that case (see #23435).
661 let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
662 if !normalize_and_test_predicates(tcx, predicates.predicates) {
663 debug!("get_vtable_methods: predicates do not hold");
667 Some((def_id, substs))
672 impl<'tcx,O> Obligation<'tcx,O> {
673 pub fn new(cause: ObligationCause<'tcx>,
674 param_env: ty::ParamEnv<'tcx>,
676 -> Obligation<'tcx, O>
678 Obligation { cause, param_env, recursion_depth: 0, predicate }
681 fn with_depth(cause: ObligationCause<'tcx>,
682 recursion_depth: usize,
683 param_env: ty::ParamEnv<'tcx>,
685 -> Obligation<'tcx, O>
687 Obligation { cause, param_env, recursion_depth, predicate }
690 pub fn misc(span: Span,
691 body_id: ast::NodeId,
692 param_env: ty::ParamEnv<'tcx>,
694 -> Obligation<'tcx, O> {
695 Obligation::new(ObligationCause::misc(span, body_id), param_env, trait_ref)
698 pub fn with<P>(&self, value: P) -> Obligation<'tcx,P> {
699 Obligation { cause: self.cause.clone(),
700 param_env: self.param_env,
701 recursion_depth: self.recursion_depth,
706 impl<'tcx> ObligationCause<'tcx> {
707 pub fn new(span: Span,
708 body_id: ast::NodeId,
709 code: ObligationCauseCode<'tcx>)
710 -> ObligationCause<'tcx> {
711 ObligationCause { span: span, body_id: body_id, code: code }
714 pub fn misc(span: Span, body_id: ast::NodeId) -> ObligationCause<'tcx> {
715 ObligationCause { span: span, body_id: body_id, code: MiscObligation }
718 pub fn dummy() -> ObligationCause<'tcx> {
719 ObligationCause { span: DUMMY_SP, body_id: ast::CRATE_NODE_ID, code: MiscObligation }
723 impl<'tcx, N> Vtable<'tcx, N> {
724 pub fn nested_obligations(self) -> Vec<N> {
726 VtableImpl(i) => i.nested,
728 VtableBuiltin(i) => i.nested,
729 VtableDefaultImpl(d) => d.nested,
730 VtableClosure(c) => c.nested,
731 VtableObject(d) => d.nested,
732 VtableFnPointer(d) => d.nested,
736 fn nested_obligations_mut(&mut self) -> &mut Vec<N> {
738 &mut VtableImpl(ref mut i) => &mut i.nested,
739 &mut VtableParam(ref mut n) => n,
740 &mut VtableBuiltin(ref mut i) => &mut i.nested,
741 &mut VtableDefaultImpl(ref mut d) => &mut d.nested,
742 &mut VtableClosure(ref mut c) => &mut c.nested,
743 &mut VtableObject(ref mut d) => &mut d.nested,
744 &mut VtableFnPointer(ref mut d) => &mut d.nested,
748 pub fn map<M, F>(self, f: F) -> Vtable<'tcx, M> where F: FnMut(N) -> M {
750 VtableImpl(i) => VtableImpl(VtableImplData {
751 impl_def_id: i.impl_def_id,
753 nested: i.nested.into_iter().map(f).collect(),
755 VtableParam(n) => VtableParam(n.into_iter().map(f).collect()),
756 VtableBuiltin(i) => VtableBuiltin(VtableBuiltinData {
757 nested: i.nested.into_iter().map(f).collect(),
759 VtableObject(o) => VtableObject(VtableObjectData {
760 upcast_trait_ref: o.upcast_trait_ref,
761 vtable_base: o.vtable_base,
762 nested: o.nested.into_iter().map(f).collect(),
764 VtableDefaultImpl(d) => VtableDefaultImpl(VtableDefaultImplData {
765 trait_def_id: d.trait_def_id,
766 nested: d.nested.into_iter().map(f).collect(),
768 VtableFnPointer(p) => VtableFnPointer(VtableFnPointerData {
770 nested: p.nested.into_iter().map(f).collect(),
772 VtableClosure(c) => VtableClosure(VtableClosureData {
773 closure_def_id: c.closure_def_id,
775 nested: c.nested.into_iter().map(f).collect(),
781 impl<'tcx> FulfillmentError<'tcx> {
782 fn new(obligation: PredicateObligation<'tcx>,
783 code: FulfillmentErrorCode<'tcx>)
784 -> FulfillmentError<'tcx>
786 FulfillmentError { obligation: obligation, code: code }
790 impl<'tcx> TraitObligation<'tcx> {
791 fn self_ty(&self) -> ty::Binder<Ty<'tcx>> {
792 ty::Binder(self.predicate.skip_binder().self_ty())
796 pub fn provide(providers: &mut ty::maps::Providers) {
797 *providers = ty::maps::Providers {
798 is_object_safe: object_safety::is_object_safe_provider,
799 specialization_graph_of: specialize::specialization_graph_provider,
804 pub fn provide_extern(providers: &mut ty::maps::Providers) {
805 *providers = ty::maps::Providers {
806 is_object_safe: object_safety::is_object_safe_provider,
807 specialization_graph_of: specialize::specialization_graph_provider,