compiler/rustc_typeck/src/check/inherited.rs

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