1 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
2 use crate::traits::{self, TraitEngine, TraitEngineExt};
4 use rustc_hir::def_id::DefId;
5 use rustc_hir::lang_items::LangItem;
6 use rustc_infer::traits::ObligationCause;
7 use rustc_middle::arena::ArenaAllocatable;
8 use rustc_middle::infer::canonical::{Canonical, CanonicalizedQueryResponse, QueryResponse};
9 use rustc_middle::traits::query::Fallible;
10 use rustc_middle::ty::subst::SubstsRef;
11 use rustc_middle::ty::ToPredicate;
12 use rustc_middle::ty::WithConstness;
13 use rustc_middle::ty::{self, Ty, TypeFoldable};
14 use rustc_span::{Span, DUMMY_SP};
18 pub use rustc_infer::infer::*;
20 pub trait InferCtxtExt<'tcx> {
21 fn type_is_copy_modulo_regions(
23 param_env: ty::ParamEnv<'tcx>,
28 fn partially_normalize_associated_types_in<T>(
30 cause: ObligationCause<'tcx>,
31 param_env: ty::ParamEnv<'tcx>,
35 T: TypeFoldable<'tcx>;
37 /// Check whether a `ty` implements given trait(trait_def_id).
40 /// - the def-id of the trait
42 /// - the *other* type parameters of the trait, excluding the self-type
43 /// - the parameter environment
45 /// Invokes `evaluate_obligation`, so in the event that evaluating
46 /// `Ty: Trait` causes overflow, EvaluatedToRecur (or EvaluatedToUnknown)
48 fn type_implements_trait(
52 params: SubstsRef<'tcx>,
53 param_env: ty::ParamEnv<'tcx>,
54 ) -> traits::EvaluationResult;
56 impl<'cx, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'cx, 'tcx> {
57 fn type_is_copy_modulo_regions(
59 param_env: ty::ParamEnv<'tcx>,
63 let ty = self.resolve_vars_if_possible(ty);
65 if !(param_env, ty).needs_infer() {
66 return ty.is_copy_modulo_regions(self.tcx.at(span), param_env);
69 let copy_def_id = self.tcx.require_lang_item(LangItem::Copy, None);
71 // This can get called from typeck (by euv), and `moves_by_default`
72 // rightly refuses to work with inference variables, but
73 // moves_by_default has a cache, which we want to use in other
75 traits::type_known_to_meet_bound_modulo_regions(self, param_env, ty, copy_def_id, span)
78 /// Normalizes associated types in `value`, potentially returning
79 /// new obligations that must further be processed.
80 fn partially_normalize_associated_types_in<T>(
82 cause: ObligationCause<'tcx>,
83 param_env: ty::ParamEnv<'tcx>,
87 T: TypeFoldable<'tcx>,
89 debug!("partially_normalize_associated_types_in(value={:?})", value);
90 let mut selcx = traits::SelectionContext::new(self);
91 let traits::Normalized { value, obligations } =
92 traits::normalize(&mut selcx, param_env, cause, value);
94 "partially_normalize_associated_types_in: result={:?} predicates={:?}",
97 InferOk { value, obligations }
100 fn type_implements_trait(
104 params: SubstsRef<'tcx>,
105 param_env: ty::ParamEnv<'tcx>,
106 ) -> traits::EvaluationResult {
108 "type_implements_trait: trait_def_id={:?}, type={:?}, params={:?}, param_env={:?}",
109 trait_def_id, ty, params, param_env
113 ty::TraitRef { def_id: trait_def_id, substs: self.tcx.mk_substs_trait(ty, params) };
115 let obligation = traits::Obligation {
116 cause: traits::ObligationCause::dummy(),
119 predicate: ty::Binder::dummy(trait_ref).without_const().to_predicate(self.tcx),
121 self.evaluate_obligation(&obligation).unwrap_or(traits::EvaluationResult::EvaluatedToErr)
125 pub trait InferCtxtBuilderExt<'tcx> {
126 fn enter_canonical_trait_query<K, R>(
128 canonical_key: &Canonical<'tcx, K>,
129 operation: impl FnOnce(&InferCtxt<'_, 'tcx>, &mut dyn TraitEngine<'tcx>, K) -> Fallible<R>,
130 ) -> Fallible<CanonicalizedQueryResponse<'tcx, R>>
132 K: TypeFoldable<'tcx>,
133 R: Debug + TypeFoldable<'tcx>,
134 Canonical<'tcx, QueryResponse<'tcx, R>>: ArenaAllocatable<'tcx>;
137 impl<'tcx> InferCtxtBuilderExt<'tcx> for InferCtxtBuilder<'tcx> {
138 /// The "main method" for a canonicalized trait query. Given the
139 /// canonical key `canonical_key`, this method will create a new
140 /// inference context, instantiate the key, and run your operation
141 /// `op`. The operation should yield up a result (of type `R`) as
142 /// well as a set of trait obligations that must be fully
143 /// satisfied. These obligations will be processed and the
144 /// canonical result created.
146 /// Returns `NoSolution` in the event of any error.
148 /// (It might be mildly nicer to implement this on `TyCtxt`, and
149 /// not `InferCtxtBuilder`, but that is a bit tricky right now.
150 /// In part because we would need a `for<'tcx>` sort of
151 /// bound for the closure and in part because it is convenient to
152 /// have `'tcx` be free on this function so that we can talk about
153 /// `K: TypeFoldable<'tcx>`.)
154 fn enter_canonical_trait_query<K, R>(
156 canonical_key: &Canonical<'tcx, K>,
157 operation: impl FnOnce(&InferCtxt<'_, 'tcx>, &mut dyn TraitEngine<'tcx>, K) -> Fallible<R>,
158 ) -> Fallible<CanonicalizedQueryResponse<'tcx, R>>
160 K: TypeFoldable<'tcx>,
161 R: Debug + TypeFoldable<'tcx>,
162 Canonical<'tcx, QueryResponse<'tcx, R>>: ArenaAllocatable<'tcx>,
164 self.enter_with_canonical(
167 |ref infcx, key, canonical_inference_vars| {
168 let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
169 let value = operation(infcx, &mut *fulfill_cx, key)?;
170 infcx.make_canonicalized_query_response(
171 canonical_inference_vars,