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