compiler/rustc_typeck/src/check/inherited.rs

   1 use super::callee::DeferredCallResolution;
   2 use super::MaybeInProgressTables;
   3
   4 use rustc_data_structures::fx::FxHashMap;
   5 use rustc_data_structures::vec_map::VecMap;
   6 use rustc_hir as hir;
   7 use rustc_hir::def_id::{DefIdMap, LocalDefId};
   8 use rustc_hir::HirIdMap;
   9 use rustc_infer::infer;
  10 use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt};
  11 use rustc_middle::ty::fold::TypeFoldable;
  12 use rustc_middle::ty::{self, OpaqueTypeKey, Ty, TyCtxt};
  13 use rustc_span::{self, Span};
  14 use rustc_trait_selection::infer::InferCtxtExt as _;
  15 use rustc_trait_selection::opaque_types::OpaqueTypeDecl;
  16 use rustc_trait_selection::traits::{self, ObligationCause, TraitEngine, TraitEngineExt};
  17
  18 use std::cell::RefCell;
  19 use std::ops::Deref;
  20
  21 /// Closures defined within the function. For example:
  22 ///
  23 ///     fn foo() {
  24 ///         bar(move|| { ... })
  25 ///     }
  26 ///
  27 /// Here, the function `foo()` and the closure passed to
  28 /// `bar()` will each have their own `FnCtxt`, but they will
  29 /// share the inherited fields.
  30 pub struct Inherited<'a, 'tcx> {
  31     pub(super) infcx: InferCtxt<'a, 'tcx>,
  32
  33     pub(super) typeck_results: super::MaybeInProgressTables<'a, 'tcx>,
  34
  35     pub(super) locals: RefCell<HirIdMap<super::LocalTy<'tcx>>>,
  36
  37     pub(super) fulfillment_cx: RefCell<Box<dyn TraitEngine<'tcx>>>,
  38
  39     // Some additional `Sized` obligations badly affect type inference.
  40     // These obligations are added in a later stage of typeck.
  41     pub(super) deferred_sized_obligations:
  42         RefCell<Vec<(Ty<'tcx>, Span, traits::ObligationCauseCode<'tcx>)>>,
  43
  44     // When we process a call like `c()` where `c` is a closure type,
  45     // we may not have decided yet whether `c` is a `Fn`, `FnMut`, or
  46     // `FnOnce` closure. In that case, we defer full resolution of the
  47     // call until upvar inference can kick in and make the
  48     // decision. We keep these deferred resolutions grouped by the
  49     // def-id of the closure, so that once we decide, we can easily go
  50     // back and process them.
  51     pub(super) deferred_call_resolutions: RefCell<DefIdMap<Vec<DeferredCallResolution<'tcx>>>>,
  52
  53     pub(super) deferred_cast_checks: RefCell<Vec<super::cast::CastCheck<'tcx>>>,
  54
  55     pub(super) deferred_generator_interiors:
  56         RefCell<Vec<(hir::BodyId, Ty<'tcx>, hir::GeneratorKind)>>,
  57
  58     // Opaque types found in explicit return types and their
  59     // associated fresh inference variable. Writeback resolves these
  60     // variables to get the concrete type, which can be used to
  61     // 'de-opaque' OpaqueTypeDecl, after typeck is done with all functions.
  62     pub(super) opaque_types: RefCell<VecMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>>,
  63
  64     /// A map from inference variables created from opaque
  65     /// type instantiations (`ty::Infer`) to the actual opaque
  66     /// type (`ty::Opaque`). Used during fallback to map unconstrained
  67     /// opaque type inference variables to their corresponding
  68     /// opaque type.
  69     pub(super) opaque_types_vars: RefCell<FxHashMap<Ty<'tcx>, Ty<'tcx>>>,
  70
  71     pub(super) body_id: Option<hir::BodyId>,
  72 }
  73
  74 impl<'a, 'tcx> Deref for Inherited<'a, 'tcx> {
  75     type Target = InferCtxt<'a, 'tcx>;
  76     fn deref(&self) -> &Self::Target {
  77         &self.infcx
  78     }
  79 }
  80
  81 /// Helper type of a temporary returned by `Inherited::build(...)`.
  82 /// Necessary because we can't write the following bound:
  83 /// `F: for<'b, 'tcx> where 'tcx FnOnce(Inherited<'b, 'tcx>)`.
  84 pub struct InheritedBuilder<'tcx> {
  85     infcx: infer::InferCtxtBuilder<'tcx>,
  86     def_id: LocalDefId,
  87 }
  88
  89 impl Inherited<'_, 'tcx> {
  90     pub fn build(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> InheritedBuilder<'tcx> {
  91         let hir_owner = tcx.hir().local_def_id_to_hir_id(def_id).owner;
  92
  93         InheritedBuilder {
  94             infcx: tcx.infer_ctxt().with_fresh_in_progress_typeck_results(hir_owner),
  95             def_id,
  96         }
  97     }
  98 }
  99
 100 impl<'tcx> InheritedBuilder<'tcx> {
 101     pub fn enter<F, R>(&mut self, f: F) -> R
 102     where
 103         F: for<'a> FnOnce(Inherited<'a, 'tcx>) -> R,
 104     {
 105         let def_id = self.def_id;
 106         self.infcx.enter(|infcx| f(Inherited::new(infcx, def_id)))
 107     }
 108 }
 109
 110 impl Inherited<'a, 'tcx> {
 111     pub(super) fn new(infcx: InferCtxt<'a, 'tcx>, def_id: LocalDefId) -> Self {
 112         let tcx = infcx.tcx;
 113         let item_id = tcx.hir().local_def_id_to_hir_id(def_id);
 114         let body_id = tcx.hir().maybe_body_owned_by(item_id);
 115
 116         Inherited {
 117             typeck_results: MaybeInProgressTables {
 118                 maybe_typeck_results: infcx.in_progress_typeck_results,
 119             },
 120             infcx,
 121             fulfillment_cx: RefCell::new(<dyn TraitEngine<'_>>::new(tcx)),
 122             locals: RefCell::new(Default::default()),
 123             deferred_sized_obligations: RefCell::new(Vec::new()),
 124             deferred_call_resolutions: RefCell::new(Default::default()),
 125             deferred_cast_checks: RefCell::new(Vec::new()),
 126             deferred_generator_interiors: RefCell::new(Vec::new()),
 127             opaque_types: RefCell::new(Default::default()),
 128             opaque_types_vars: RefCell::new(Default::default()),
 129             body_id,
 130         }
 131     }
 132
 133     pub(super) fn register_predicate(&self, obligation: traits::PredicateObligation<'tcx>) {
 134         debug!("register_predicate({:?})", obligation);
 135         if obligation.has_escaping_bound_vars() {
 136             span_bug!(obligation.cause.span, "escaping bound vars in predicate {:?}", obligation);
 137         }
 138         self.fulfillment_cx.borrow_mut().register_predicate_obligation(self, obligation);
 139     }
 140
 141     pub(super) fn register_predicates<I>(&self, obligations: I)
 142     where
 143         I: IntoIterator<Item = traits::PredicateObligation<'tcx>>,
 144     {
 145         for obligation in obligations {
 146             self.register_predicate(obligation);
 147         }
 148     }
 149
 150     pub(super) fn register_infer_ok_obligations<T>(&self, infer_ok: InferOk<'tcx, T>) -> T {
 151         self.register_predicates(infer_ok.obligations);
 152         infer_ok.value
 153     }
 154
 155     pub(super) fn normalize_associated_types_in<T>(
 156         &self,
 157         span: Span,
 158         body_id: hir::HirId,
 159         param_env: ty::ParamEnv<'tcx>,
 160         value: T,
 161     ) -> T
 162     where
 163         T: TypeFoldable<'tcx>,
 164     {
 165         self.normalize_associated_types_in_with_cause(
 166             ObligationCause::misc(span, body_id),
 167             param_env,
 168             value,
 169         )
 170     }
 171
 172     pub(super) fn normalize_associated_types_in_with_cause<T>(
 173         &self,
 174         cause: ObligationCause<'tcx>,
 175         param_env: ty::ParamEnv<'tcx>,
 176         value: T,
 177     ) -> T
 178     where
 179         T: TypeFoldable<'tcx>,
 180     {
 181         let ok = self.partially_normalize_associated_types_in(cause, param_env, value);
 182         debug!(?ok);
 183         self.register_infer_ok_obligations(ok)
 184     }
 185 }