compiler/rustc_infer/src/traits/engine.rs

   1 use crate::infer::InferCtxt;
   2 use crate::traits::Obligation;
   3 use rustc_data_structures::fx::FxHashMap;
   4 use rustc_hir::def_id::DefId;
   5 use rustc_middle::ty::{self, ToPredicate, Ty};
   6
   7 use super::FulfillmentError;
   8 use super::{ObligationCause, PredicateObligation};
   9
  10 pub trait TraitEngine<'tcx>: 'tcx {
  11     fn normalize_projection_type(
  12         &mut self,
  13         infcx: &InferCtxt<'tcx>,
  14         param_env: ty::ParamEnv<'tcx>,
  15         projection_ty: ty::ProjectionTy<'tcx>,
  16         cause: ObligationCause<'tcx>,
  17     ) -> Ty<'tcx>;
  18
  19     /// Requires that `ty` must implement the trait with `def_id` in
  20     /// the given environment. This trait must not have any type
  21     /// parameters (except for `Self`).
  22     fn register_bound(
  23         &mut self,
  24         infcx: &InferCtxt<'tcx>,
  25         param_env: ty::ParamEnv<'tcx>,
  26         ty: Ty<'tcx>,
  27         def_id: DefId,
  28         cause: ObligationCause<'tcx>,
  29     ) {
  30         let trait_ref = ty::TraitRef { def_id, substs: infcx.tcx.mk_substs_trait(ty, &[]) };
  31         self.register_predicate_obligation(
  32             infcx,
  33             Obligation {
  34                 cause,
  35                 recursion_depth: 0,
  36                 param_env,
  37                 predicate: ty::Binder::dummy(trait_ref).without_const().to_predicate(infcx.tcx),
  38             },
  39         );
  40     }
  41
  42     fn register_predicate_obligation(
  43         &mut self,
  44         infcx: &InferCtxt<'tcx>,
  45         obligation: PredicateObligation<'tcx>,
  46     );
  47
  48     fn select_all_or_error(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
  49
  50     fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
  51
  52     fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>>;
  53
  54     fn relationships(&mut self) -> &mut FxHashMap<ty::TyVid, ty::FoundRelationships>;
  55 }
  56
  57 pub trait TraitEngineExt<'tcx> {
  58     fn register_predicate_obligations(
  59         &mut self,
  60         infcx: &InferCtxt<'tcx>,
  61         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
  62     );
  63 }
  64
  65 impl<'tcx, T: ?Sized + TraitEngine<'tcx>> TraitEngineExt<'tcx> for T {
  66     fn register_predicate_obligations(
  67         &mut self,
  68         infcx: &InferCtxt<'tcx>,
  69         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
  70     ) {
  71         for obligation in obligations {
  72             self.register_predicate_obligation(infcx, obligation);
  73         }
  74     }
  75 }