src/librustc_infer/traits/engine.rs

   1 use crate::infer::InferCtxt;
   2 use crate::traits::Obligation;
   3 use rustc::ty::{self, ToPredicate, Ty, TyCtxt, WithConstness};
   4 use rustc_hir::def_id::DefId;
   5
   6 use super::{FulfillmentContext, FulfillmentError};
   7 use super::{ObligationCause, PredicateObligation};
   8
   9 pub trait TraitEngine<'tcx>: 'tcx {
  10     fn normalize_projection_type(
  11         &mut self,
  12         infcx: &InferCtxt<'_, 'tcx>,
  13         param_env: ty::ParamEnv<'tcx>,
  14         projection_ty: ty::ProjectionTy<'tcx>,
  15         cause: ObligationCause<'tcx>,
  16     ) -> Ty<'tcx>;
  17
  18     /// Requires that `ty` must implement the trait with `def_id` in
  19     /// the given environment. This trait must not have any type
  20     /// parameters (except for `Self`).
  21     fn register_bound(
  22         &mut self,
  23         infcx: &InferCtxt<'_, 'tcx>,
  24         param_env: ty::ParamEnv<'tcx>,
  25         ty: Ty<'tcx>,
  26         def_id: DefId,
  27         cause: ObligationCause<'tcx>,
  28     ) {
  29         let trait_ref = ty::TraitRef { def_id, substs: infcx.tcx.mk_substs_trait(ty, &[]) };
  30         self.register_predicate_obligation(
  31             infcx,
  32             Obligation {
  33                 cause,
  34                 recursion_depth: 0,
  35                 param_env,
  36                 predicate: trait_ref.without_const().to_predicate(),
  37             },
  38         );
  39     }
  40
  41     fn register_predicate_obligation(
  42         &mut self,
  43         infcx: &InferCtxt<'_, 'tcx>,
  44         obligation: PredicateObligation<'tcx>,
  45     );
  46
  47     fn select_all_or_error(
  48         &mut self,
  49         infcx: &InferCtxt<'_, 'tcx>,
  50     ) -> Result<(), Vec<FulfillmentError<'tcx>>>;
  51
  52     fn select_where_possible(
  53         &mut self,
  54         infcx: &InferCtxt<'_, 'tcx>,
  55     ) -> Result<(), Vec<FulfillmentError<'tcx>>>;
  56
  57     fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>>;
  58 }
  59
  60 pub trait TraitEngineExt<'tcx> {
  61     fn register_predicate_obligations(
  62         &mut self,
  63         infcx: &InferCtxt<'_, 'tcx>,
  64         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
  65     );
  66 }
  67
  68 impl<T: ?Sized + TraitEngine<'tcx>> TraitEngineExt<'tcx> for T {
  69     fn register_predicate_obligations(
  70         &mut self,
  71         infcx: &InferCtxt<'_, 'tcx>,
  72         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
  73     ) {
  74         for obligation in obligations {
  75             self.register_predicate_obligation(infcx, obligation);
  76         }
  77     }
  78 }
  79
  80 impl dyn TraitEngine<'tcx> {
  81     pub fn new(_tcx: TyCtxt<'tcx>) -> Box<Self> {
  82         Box::new(FulfillmentContext::new())
  83     }
  84 }