compiler/rustc_infer/src/traits/engine.rs

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