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::const_val::ConstEvalErr;
22 use middle::free_region::FreeRegionMap;
23 use ty::subst::Substs;
24 use ty::{self, AdtKind, Ty, TyCtxt, TypeFoldable, ToPredicate};
25 use ty::error::{ExpectedFound, TypeError};
26 use infer::{InferCtxt};
30 use syntax_pos::{Span, DUMMY_SP};
32 pub use self::coherence::{orphan_check, overlapping_impls, OrphanCheckErr, OverlapResult};
33 pub use self::fulfill::{FulfillmentContext, 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::on_unimplemented::{OnUnimplementedDirective, OnUnimplementedNote};
40 pub use self::select::{EvaluationCache, SelectionContext, SelectionCache};
41 pub use self::select::IntercrateAmbiguityCause;
42 pub use self::specialize::{OverlapError, specialization_graph, 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;
63 /// An `Obligation` represents some trait reference (e.g. `int:Eq`) for
64 /// which the vtable must be found. The process of finding a vtable is
65 /// called "resolving" the `Obligation`. This process consists of
66 /// either identifying an `impl` (e.g., `impl Eq for int`) that
67 /// provides the required vtable, or else finding a bound that is in
68 /// scope. The eventual result is usually a `Selection` (defined below).
69 #[derive(Clone, PartialEq, Eq)]
70 pub struct Obligation<'tcx, T> {
71 pub cause: ObligationCause<'tcx>,
72 pub param_env: ty::ParamEnv<'tcx>,
73 pub recursion_depth: usize,
77 pub type PredicateObligation<'tcx> = Obligation<'tcx, ty::Predicate<'tcx>>;
78 pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
80 /// Why did we incur this obligation? Used for error reporting.
81 #[derive(Clone, Debug, PartialEq, Eq)]
82 pub struct ObligationCause<'tcx> {
85 // The id of the fn body that triggered this obligation. This is
86 // used for region obligations to determine the precise
87 // environment in which the region obligation should be evaluated
88 // (in particular, closures can add new assumptions). See the
89 // field `region_obligations` of the `FulfillmentContext` for more
91 pub body_id: ast::NodeId,
93 pub code: ObligationCauseCode<'tcx>
96 #[derive(Clone, Debug, PartialEq, Eq)]
97 pub enum ObligationCauseCode<'tcx> {
98 /// Not well classified or should be obvious from span.
101 /// A slice or array is WF only if `T: Sized`
104 /// A tuple is WF only if its middle elements are Sized
107 /// This is the trait reference from the given projection
108 ProjectionWf(ty::ProjectionTy<'tcx>),
110 /// In an impl of trait X for type Y, type Y must
111 /// also implement all supertraits of X.
112 ItemObligation(DefId),
114 /// A type like `&'a T` is WF only if `T: 'a`.
115 ReferenceOutlivesReferent(Ty<'tcx>),
117 /// A type like `Box<Foo<'a> + 'b>` is WF only if `'b: 'a`.
118 ObjectTypeBound(Ty<'tcx>, ty::Region<'tcx>),
120 /// Obligation incurred due to an object cast.
121 ObjectCastObligation(/* Object type */ Ty<'tcx>),
123 // Various cases where expressions must be sized/copy/etc:
124 /// L = X implies that L is Sized
126 /// (x1, .., xn) must be Sized
127 TupleInitializerSized,
128 /// S { ... } must be Sized
129 StructInitializerSized,
130 /// Type of each variable must be Sized
131 VariableType(ast::NodeId),
132 /// Return type must be Sized
134 /// [T,..n] --> T must be Copy
137 /// Types of fields (other than the last) in a struct must be sized.
140 /// Constant expressions must be sized.
143 /// static items must have `Sync` type
146 BuiltinDerivedObligation(DerivedObligationCause<'tcx>),
148 ImplDerivedObligation(DerivedObligationCause<'tcx>),
150 /// error derived when matching traits/impls; see ObligationCause for more details
151 CompareImplMethodObligation {
152 item_name: ast::Name,
153 impl_item_def_id: DefId,
154 trait_item_def_id: DefId,
155 lint_id: Option<ast::NodeId>,
158 /// Checking that this expression can be assigned where it needs to be
159 // FIXME(eddyb) #11161 is the original Expr required?
162 /// Computing common supertype in the arms of a match expression
163 MatchExpressionArm { arm_span: Span,
164 source: hir::MatchSource },
166 /// Computing common supertype in an if expression
169 /// Computing common supertype of an if expression with no else counter-part
170 IfExpressionWithNoElse,
175 /// `main` has wrong type
178 /// `start` has wrong type
181 /// intrinsic has wrong type
187 /// `return` with no expression
190 /// `return` with an expression
191 ReturnType(ast::NodeId),
193 /// Block implicit return
194 BlockTailExpression(ast::NodeId),
197 #[derive(Clone, Debug, PartialEq, Eq)]
198 pub struct DerivedObligationCause<'tcx> {
199 /// The trait reference of the parent obligation that led to the
200 /// current obligation. Note that only trait obligations lead to
201 /// derived obligations, so we just store the trait reference here
203 parent_trait_ref: ty::PolyTraitRef<'tcx>,
205 /// The parent trait had this cause
206 parent_code: Rc<ObligationCauseCode<'tcx>>
209 pub type Obligations<'tcx, O> = Vec<Obligation<'tcx, O>>;
210 pub type PredicateObligations<'tcx> = Vec<PredicateObligation<'tcx>>;
211 pub type TraitObligations<'tcx> = Vec<TraitObligation<'tcx>>;
213 pub type Selection<'tcx> = Vtable<'tcx, PredicateObligation<'tcx>>;
215 #[derive(Clone,Debug)]
216 pub enum SelectionError<'tcx> {
218 OutputTypeParameterMismatch(ty::PolyTraitRef<'tcx>,
219 ty::PolyTraitRef<'tcx>,
220 ty::error::TypeError<'tcx>),
221 TraitNotObjectSafe(DefId),
222 ConstEvalFailure(ConstEvalErr<'tcx>),
225 pub struct FulfillmentError<'tcx> {
226 pub obligation: PredicateObligation<'tcx>,
227 pub code: FulfillmentErrorCode<'tcx>
231 pub enum FulfillmentErrorCode<'tcx> {
232 CodeSelectionError(SelectionError<'tcx>),
233 CodeProjectionError(MismatchedProjectionTypes<'tcx>),
234 CodeSubtypeError(ExpectedFound<Ty<'tcx>>,
235 TypeError<'tcx>), // always comes from a SubtypePredicate
239 /// When performing resolution, it is typically the case that there
240 /// can be one of three outcomes:
242 /// - `Ok(Some(r))`: success occurred with result `r`
243 /// - `Ok(None)`: could not definitely determine anything, usually due
244 /// to inconclusive type inference.
245 /// - `Err(e)`: error `e` occurred
246 pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>;
248 /// Given the successful resolution of an obligation, the `Vtable`
249 /// indicates where the vtable comes from. Note that while we call this
250 /// a "vtable", it does not necessarily indicate dynamic dispatch at
251 /// runtime. `Vtable` instances just tell the compiler where to find
252 /// methods, but in generic code those methods are typically statically
253 /// dispatched -- only when an object is constructed is a `Vtable`
254 /// instance reified into an actual vtable.
256 /// For example, the vtable may be tied to a specific impl (case A),
257 /// or it may be relative to some bound that is in scope (case B).
261 /// impl<T:Clone> Clone<T> for Option<T> { ... } // Impl_1
262 /// impl<T:Clone> Clone<T> for Box<T> { ... } // Impl_2
263 /// impl Clone for int { ... } // Impl_3
265 /// fn foo<T:Clone>(concrete: Option<Box<int>>,
267 /// mixed: Option<T>) {
269 /// // Case A: Vtable points at a specific impl. Only possible when
270 /// // type is concretely known. If the impl itself has bounded
271 /// // type parameters, Vtable will carry resolutions for those as well:
272 /// concrete.clone(); // Vtable(Impl_1, [Vtable(Impl_2, [Vtable(Impl_3)])])
274 /// // Case B: Vtable must be provided by caller. This applies when
275 /// // type is a type parameter.
276 /// param.clone(); // VtableParam
278 /// // Case C: A mix of cases A and B.
279 /// mixed.clone(); // Vtable(Impl_1, [VtableParam])
283 /// ### The type parameter `N`
285 /// See explanation on `VtableImplData`.
287 pub enum Vtable<'tcx, N> {
288 /// Vtable identifying a particular impl.
289 VtableImpl(VtableImplData<'tcx, N>),
291 /// Vtable for default trait implementations
292 /// This carries the information and nested obligations with regards
293 /// to a default implementation for a trait `Trait`. The nested obligations
294 /// ensure the trait implementation holds for all the constituent types.
295 VtableDefaultImpl(VtableDefaultImplData<N>),
297 /// Successful resolution to an obligation provided by the caller
298 /// for some type parameter. The `Vec<N>` represents the
299 /// obligations incurred from normalizing the where-clause (if
303 /// Virtual calls through an object
304 VtableObject(VtableObjectData<'tcx, N>),
306 /// Successful resolution for a builtin trait.
307 VtableBuiltin(VtableBuiltinData<N>),
309 /// Vtable automatically generated for a closure. The def ID is the ID
310 /// of the closure expression. This is a `VtableImpl` in spirit, but the
311 /// impl is generated by the compiler and does not appear in the source.
312 VtableClosure(VtableClosureData<'tcx, N>),
314 /// Same as above, but for a fn pointer type with the given signature.
315 VtableFnPointer(VtableFnPointerData<'tcx, N>),
317 /// Vtable automatically generated for a generator
318 VtableGenerator(VtableGeneratorData<'tcx, N>),
321 /// Identifies a particular impl in the source, along with a set of
322 /// substitutions from the impl's type/lifetime parameters. The
323 /// `nested` vector corresponds to the nested obligations attached to
324 /// the impl's type parameters.
326 /// The type parameter `N` indicates the type used for "nested
327 /// obligations" that are required by the impl. During type check, this
328 /// is `Obligation`, as one might expect. During trans, however, this
329 /// is `()`, because trans only requires a shallow resolution of an
330 /// impl, and nested obligations are satisfied later.
331 #[derive(Clone, PartialEq, Eq)]
332 pub struct VtableImplData<'tcx, N> {
333 pub impl_def_id: DefId,
334 pub substs: &'tcx Substs<'tcx>,
338 #[derive(Clone, PartialEq, Eq)]
339 pub struct VtableGeneratorData<'tcx, N> {
340 pub closure_def_id: DefId,
341 pub substs: ty::ClosureSubsts<'tcx>,
342 /// Nested obligations. This can be non-empty if the generator
343 /// signature contains associated types.
347 #[derive(Clone, PartialEq, Eq)]
348 pub struct VtableClosureData<'tcx, N> {
349 pub closure_def_id: DefId,
350 pub substs: ty::ClosureSubsts<'tcx>,
351 /// Nested obligations. This can be non-empty if the closure
352 /// signature contains associated types.
357 pub struct VtableDefaultImplData<N> {
358 pub trait_def_id: DefId,
363 pub struct VtableBuiltinData<N> {
367 /// A vtable for some object-safe trait `Foo` automatically derived
368 /// for the object type `Foo`.
369 #[derive(PartialEq,Eq,Clone)]
370 pub struct VtableObjectData<'tcx, N> {
371 /// `Foo` upcast to the obligation trait. This will be some supertrait of `Foo`.
372 pub upcast_trait_ref: ty::PolyTraitRef<'tcx>,
374 /// The vtable is formed by concatenating together the method lists of
375 /// the base object trait and all supertraits; this is the start of
376 /// `upcast_trait_ref`'s methods in that vtable.
377 pub vtable_base: usize,
382 #[derive(Clone, PartialEq, Eq)]
383 pub struct VtableFnPointerData<'tcx, N> {
384 pub fn_ty: ty::Ty<'tcx>,
388 /// Creates predicate obligations from the generic bounds.
389 pub fn predicates_for_generics<'tcx>(cause: ObligationCause<'tcx>,
390 param_env: ty::ParamEnv<'tcx>,
391 generic_bounds: &ty::InstantiatedPredicates<'tcx>)
392 -> PredicateObligations<'tcx>
394 util::predicates_for_generics(cause, 0, param_env, generic_bounds)
397 /// Determines whether the type `ty` is known to meet `bound` and
398 /// returns true if so. Returns false if `ty` either does not meet
399 /// `bound` or is not known to meet bound (note that this is
400 /// conservative towards *no impl*, which is the opposite of the
401 /// `evaluate` methods).
402 pub fn type_known_to_meet_bound<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
403 param_env: ty::ParamEnv<'tcx>,
409 debug!("type_known_to_meet_bound(ty={:?}, bound={:?})",
411 infcx.tcx.item_path_str(def_id));
413 let trait_ref = ty::TraitRef {
415 substs: infcx.tcx.mk_substs_trait(ty, &[]),
417 let obligation = Obligation {
419 cause: ObligationCause::misc(span, ast::DUMMY_NODE_ID),
421 predicate: trait_ref.to_predicate(),
424 let result = SelectionContext::new(infcx)
425 .evaluate_obligation_conservatively(&obligation);
426 debug!("type_known_to_meet_ty={:?} bound={} => {:?}",
427 ty, infcx.tcx.item_path_str(def_id), result);
429 if result && (ty.has_infer_types() || ty.has_closure_types()) {
430 // Because of inference "guessing", selection can sometimes claim
431 // to succeed while the success requires a guess. To ensure
432 // this function's result remains infallible, we must confirm
433 // that guess. While imperfect, I believe this is sound.
435 let mut fulfill_cx = FulfillmentContext::new();
437 // We can use a dummy node-id here because we won't pay any mind
438 // to region obligations that arise (there shouldn't really be any
440 let cause = ObligationCause::misc(span, ast::DUMMY_NODE_ID);
442 fulfill_cx.register_bound(infcx, param_env, ty, def_id, cause);
444 // Note: we only assume something is `Copy` if we can
445 // *definitively* show that it implements `Copy`. Otherwise,
446 // assume it is move; linear is always ok.
447 match fulfill_cx.select_all_or_error(infcx) {
449 debug!("type_known_to_meet_bound: ty={:?} bound={} success",
451 infcx.tcx.item_path_str(def_id));
455 debug!("type_known_to_meet_bound: ty={:?} bound={} errors={:?}",
457 infcx.tcx.item_path_str(def_id),
467 // FIXME: this is gonna need to be removed ...
468 /// Normalizes the parameter environment, reporting errors if they occur.
469 pub fn normalize_param_env_or_error<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
470 region_context: DefId,
471 unnormalized_env: ty::ParamEnv<'tcx>,
472 cause: ObligationCause<'tcx>)
473 -> ty::ParamEnv<'tcx>
475 // I'm not wild about reporting errors here; I'd prefer to
476 // have the errors get reported at a defined place (e.g.,
477 // during typeck). Instead I have all parameter
478 // environments, in effect, going through this function
479 // and hence potentially reporting errors. This ensurse of
480 // course that we never forget to normalize (the
481 // alternative seemed like it would involve a lot of
482 // manual invocations of this fn -- and then we'd have to
483 // deal with the errors at each of those sites).
485 // In any case, in practice, typeck constructs all the
486 // parameter environments once for every fn as it goes,
487 // and errors will get reported then; so after typeck we
488 // can be sure that no errors should occur.
490 let span = cause.span;
492 debug!("normalize_param_env_or_error(unnormalized_env={:?})",
495 let predicates: Vec<_> =
496 util::elaborate_predicates(tcx, unnormalized_env.caller_bounds.to_vec())
497 .filter(|p| !p.is_global()) // (*)
500 // (*) Any predicate like `i32: Trait<u32>` or whatever doesn't
501 // need to be in the *environment* to be proven, so screen those
502 // out. This is important for the soundness of inter-fn
503 // caching. Note though that we should probably check that these
504 // predicates hold at the point where the environment is
505 // constructed, but I am not currently doing so out of laziness.
508 debug!("normalize_param_env_or_error: elaborated-predicates={:?}",
511 let elaborated_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates),
512 unnormalized_env.reveal);
514 tcx.infer_ctxt().enter(|infcx| {
515 let predicates = match fully_normalize(
519 // You would really want to pass infcx.param_env.caller_bounds here,
520 // but that is an interned slice, and fully_normalize takes &T and returns T, so
521 // without further refactoring, a slice can't be used. Luckily, we still have the
522 // predicate vector from which we created the ParamEnv in infcx, so we
523 // can pass that instead. It's roundabout and a bit brittle, but this code path
524 // ought to be refactored anyway, and until then it saves us from having to copy.
527 Ok(predicates) => predicates,
529 infcx.report_fulfillment_errors(&errors, None);
530 // An unnormalized env is better than nothing.
531 return elaborated_env;
535 debug!("normalize_param_env_or_error: normalized predicates={:?}",
538 let region_scope_tree = region::ScopeTree::default();
539 let free_regions = FreeRegionMap::new();
540 infcx.resolve_regions_and_report_errors(region_context, ®ion_scope_tree, &free_regions);
541 let predicates = match infcx.fully_resolve(&predicates) {
542 Ok(predicates) => predicates,
544 // If we encounter a fixup error, it means that some type
545 // variable wound up unconstrained. I actually don't know
546 // if this can happen, and I certainly don't expect it to
547 // happen often, but if it did happen it probably
548 // represents a legitimate failure due to some kind of
549 // unconstrained variable, and it seems better not to ICE,
550 // all things considered.
551 tcx.sess.span_err(span, &fixup_err.to_string());
552 // An unnormalized env is better than nothing.
553 return elaborated_env;
557 let predicates = match tcx.lift_to_global(&predicates) {
558 Some(predicates) => predicates,
559 None => return elaborated_env,
562 debug!("normalize_param_env_or_error: resolved predicates={:?}",
565 ty::ParamEnv::new(tcx.intern_predicates(&predicates), unnormalized_env.reveal)
569 pub fn fully_normalize<'a, 'gcx, 'tcx, T>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
570 cause: ObligationCause<'tcx>,
571 param_env: ty::ParamEnv<'tcx>,
573 -> Result<T, Vec<FulfillmentError<'tcx>>>
574 where T : TypeFoldable<'tcx>
576 debug!("fully_normalize(value={:?})", value);
578 let selcx = &mut SelectionContext::new(infcx);
579 // FIXME (@jroesch) ISSUE 26721
580 // I'm not sure if this is a bug or not, needs further investigation.
581 // It appears that by reusing the fulfillment_cx here we incur more
582 // obligations and later trip an asssertion on regionck.rs line 337.
584 // The two possibilities I see is:
585 // - normalization is not actually fully happening and we
586 // have a bug else where
587 // - we are adding a duplicate bound into the list causing
588 // its size to change.
590 // I think we should probably land this refactor and then come
591 // back to this is a follow-up patch.
592 let mut fulfill_cx = FulfillmentContext::new();
594 let Normalized { value: normalized_value, obligations } =
595 project::normalize(selcx, param_env, cause, value);
596 debug!("fully_normalize: normalized_value={:?} obligations={:?}",
599 for obligation in obligations {
600 fulfill_cx.register_predicate_obligation(selcx.infcx(), obligation);
603 debug!("fully_normalize: select_all_or_error start");
604 match fulfill_cx.select_all_or_error(infcx) {
607 debug!("fully_normalize: error={:?}", e);
611 debug!("fully_normalize: select_all_or_error complete");
612 let resolved_value = infcx.resolve_type_vars_if_possible(&normalized_value);
613 debug!("fully_normalize: resolved_value={:?}", resolved_value);
617 /// Normalizes the predicates and checks whether they hold in an empty
618 /// environment. If this returns false, then either normalize
619 /// encountered an error or one of the predicates did not hold. Used
620 /// when creating vtables to check for unsatisfiable methods.
621 pub fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
622 predicates: Vec<ty::Predicate<'tcx>>)
625 debug!("normalize_and_test_predicates(predicates={:?})",
628 let result = tcx.infer_ctxt().enter(|infcx| {
629 let param_env = ty::ParamEnv::empty(Reveal::All);
630 let mut selcx = SelectionContext::new(&infcx);
631 let mut fulfill_cx = FulfillmentContext::new();
632 let cause = ObligationCause::dummy();
633 let Normalized { value: predicates, obligations } =
634 normalize(&mut selcx, param_env, cause.clone(), &predicates);
635 for obligation in obligations {
636 fulfill_cx.register_predicate_obligation(&infcx, obligation);
638 for predicate in predicates {
639 let obligation = Obligation::new(cause.clone(), param_env, predicate);
640 fulfill_cx.register_predicate_obligation(&infcx, obligation);
643 fulfill_cx.select_all_or_error(&infcx).is_ok()
645 debug!("normalize_and_test_predicates(predicates={:?}) = {:?}",
650 /// Given a trait `trait_ref`, iterates the vtable entries
651 /// that come from `trait_ref`, including its supertraits.
652 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
653 pub fn get_vtable_methods<'a, 'tcx>(
654 tcx: TyCtxt<'a, 'tcx, 'tcx>,
655 trait_ref: ty::PolyTraitRef<'tcx>)
656 -> impl Iterator<Item=Option<(DefId, &'tcx Substs<'tcx>)>> + 'a
658 debug!("get_vtable_methods({:?})", trait_ref);
660 supertraits(tcx, trait_ref).flat_map(move |trait_ref| {
661 let trait_methods = tcx.associated_items(trait_ref.def_id())
662 .filter(|item| item.kind == ty::AssociatedKind::Method);
664 // Now list each method's DefId and Substs (for within its trait).
665 // If the method can never be called from this object, produce None.
666 trait_methods.map(move |trait_method| {
667 debug!("get_vtable_methods: trait_method={:?}", trait_method);
668 let def_id = trait_method.def_id;
670 // Some methods cannot be called on an object; skip those.
671 if !tcx.is_vtable_safe_method(trait_ref.def_id(), &trait_method) {
672 debug!("get_vtable_methods: not vtable safe");
676 // the method may have some early-bound lifetimes, add
678 let substs = Substs::for_item(tcx, def_id,
679 |_, _| tcx.types.re_erased,
680 |def, _| trait_ref.substs().type_for_def(def));
682 // the trait type may have higher-ranked lifetimes in it;
683 // so erase them if they appear, so that we get the type
684 // at some particular call site
685 let substs = tcx.erase_late_bound_regions_and_normalize(&ty::Binder(substs));
687 // It's possible that the method relies on where clauses that
688 // do not hold for this particular set of type parameters.
689 // Note that this method could then never be called, so we
690 // do not want to try and trans it, in that case (see #23435).
691 let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
692 if !normalize_and_test_predicates(tcx, predicates.predicates) {
693 debug!("get_vtable_methods: predicates do not hold");
697 Some((def_id, substs))
702 impl<'tcx,O> Obligation<'tcx,O> {
703 pub fn new(cause: ObligationCause<'tcx>,
704 param_env: ty::ParamEnv<'tcx>,
706 -> Obligation<'tcx, O>
708 Obligation { cause, param_env, recursion_depth: 0, predicate }
711 fn with_depth(cause: ObligationCause<'tcx>,
712 recursion_depth: usize,
713 param_env: ty::ParamEnv<'tcx>,
715 -> Obligation<'tcx, O>
717 Obligation { cause, param_env, recursion_depth, predicate }
720 pub fn misc(span: Span,
721 body_id: ast::NodeId,
722 param_env: ty::ParamEnv<'tcx>,
724 -> Obligation<'tcx, O> {
725 Obligation::new(ObligationCause::misc(span, body_id), param_env, trait_ref)
728 pub fn with<P>(&self, value: P) -> Obligation<'tcx,P> {
729 Obligation { cause: self.cause.clone(),
730 param_env: self.param_env,
731 recursion_depth: self.recursion_depth,
736 impl<'tcx> ObligationCause<'tcx> {
737 pub fn new(span: Span,
738 body_id: ast::NodeId,
739 code: ObligationCauseCode<'tcx>)
740 -> ObligationCause<'tcx> {
741 ObligationCause { span: span, body_id: body_id, code: code }
744 pub fn misc(span: Span, body_id: ast::NodeId) -> ObligationCause<'tcx> {
745 ObligationCause { span: span, body_id: body_id, code: MiscObligation }
748 pub fn dummy() -> ObligationCause<'tcx> {
749 ObligationCause { span: DUMMY_SP, body_id: ast::CRATE_NODE_ID, code: MiscObligation }
753 impl<'tcx, N> Vtable<'tcx, N> {
754 pub fn nested_obligations(self) -> Vec<N> {
756 VtableImpl(i) => i.nested,
758 VtableBuiltin(i) => i.nested,
759 VtableDefaultImpl(d) => d.nested,
760 VtableClosure(c) => c.nested,
761 VtableGenerator(c) => c.nested,
762 VtableObject(d) => d.nested,
763 VtableFnPointer(d) => d.nested,
767 fn nested_obligations_mut(&mut self) -> &mut Vec<N> {
769 &mut VtableImpl(ref mut i) => &mut i.nested,
770 &mut VtableParam(ref mut n) => n,
771 &mut VtableBuiltin(ref mut i) => &mut i.nested,
772 &mut VtableDefaultImpl(ref mut d) => &mut d.nested,
773 &mut VtableGenerator(ref mut c) => &mut c.nested,
774 &mut VtableClosure(ref mut c) => &mut c.nested,
775 &mut VtableObject(ref mut d) => &mut d.nested,
776 &mut VtableFnPointer(ref mut d) => &mut d.nested,
780 pub fn map<M, F>(self, f: F) -> Vtable<'tcx, M> where F: FnMut(N) -> M {
782 VtableImpl(i) => VtableImpl(VtableImplData {
783 impl_def_id: i.impl_def_id,
785 nested: i.nested.into_iter().map(f).collect(),
787 VtableParam(n) => VtableParam(n.into_iter().map(f).collect()),
788 VtableBuiltin(i) => VtableBuiltin(VtableBuiltinData {
789 nested: i.nested.into_iter().map(f).collect(),
791 VtableObject(o) => VtableObject(VtableObjectData {
792 upcast_trait_ref: o.upcast_trait_ref,
793 vtable_base: o.vtable_base,
794 nested: o.nested.into_iter().map(f).collect(),
796 VtableDefaultImpl(d) => VtableDefaultImpl(VtableDefaultImplData {
797 trait_def_id: d.trait_def_id,
798 nested: d.nested.into_iter().map(f).collect(),
800 VtableFnPointer(p) => VtableFnPointer(VtableFnPointerData {
802 nested: p.nested.into_iter().map(f).collect(),
804 VtableGenerator(c) => VtableGenerator(VtableGeneratorData {
805 closure_def_id: c.closure_def_id,
807 nested: c.nested.into_iter().map(f).collect(),
809 VtableClosure(c) => VtableClosure(VtableClosureData {
810 closure_def_id: c.closure_def_id,
812 nested: c.nested.into_iter().map(f).collect(),
818 impl<'tcx> FulfillmentError<'tcx> {
819 fn new(obligation: PredicateObligation<'tcx>,
820 code: FulfillmentErrorCode<'tcx>)
821 -> FulfillmentError<'tcx>
823 FulfillmentError { obligation: obligation, code: code }
827 impl<'tcx> TraitObligation<'tcx> {
828 fn self_ty(&self) -> ty::Binder<Ty<'tcx>> {
829 ty::Binder(self.predicate.skip_binder().self_ty())
833 pub fn provide(providers: &mut ty::maps::Providers) {
834 *providers = ty::maps::Providers {
835 is_object_safe: object_safety::is_object_safe_provider,
836 specialization_graph_of: specialize::specialization_graph_provider,
837 specializes: specialize::specializes,
842 pub fn provide_extern(providers: &mut ty::maps::Providers) {
843 *providers = ty::maps::Providers {
844 is_object_safe: object_safety::is_object_safe_provider,
845 specialization_graph_of: specialize::specialization_graph_provider,
846 specializes: specialize::specializes,