src/librustc_traits/normalize_projection_ty.rs

   1 use rustc::infer::canonical::{Canonical, QueryResponse};
   2 use rustc::traits::query::{normalize::NormalizationResult, CanonicalProjectionGoal, NoSolution};
   3 use rustc::traits::{self, ObligationCause, SelectionContext, TraitEngineExt};
   4 use rustc::ty::query::Providers;
   5 use rustc::ty::{ParamEnvAnd, TyCtxt};
   6 use rustc_data_structures::sync::Lrc;
   7 use std::sync::atomic::Ordering;
   8 use syntax::ast::DUMMY_NODE_ID;
   9 use syntax_pos::DUMMY_SP;
  10
  11 crate fn provide(p: &mut Providers) {
  12     *p = Providers {
  13         normalize_projection_ty,
  14         ..*p
  15     };
  16 }
  17
  18 fn normalize_projection_ty<'tcx>(
  19     tcx: TyCtxt<'_, 'tcx, 'tcx>,
  20     goal: CanonicalProjectionGoal<'tcx>,
  21 ) -> Result<Lrc<Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>>, NoSolution> {
  22     debug!("normalize_provider(goal={:#?})", goal);
  23
  24     tcx.sess
  25         .perf_stats
  26         .normalize_projection_ty
  27         .fetch_add(1, Ordering::Relaxed);
  28     tcx.infer_ctxt().enter_canonical_trait_query(
  29         &goal,
  30         |infcx,
  31          fulfill_cx,
  32          ParamEnvAnd {
  33              param_env,
  34              value: goal,
  35          }| {
  36             let selcx = &mut SelectionContext::new(infcx);
  37             let cause = ObligationCause::misc(DUMMY_SP, DUMMY_NODE_ID);
  38             let mut obligations = vec![];
  39             let answer = traits::normalize_projection_type(
  40                 selcx,
  41                 param_env,
  42                 goal,
  43                 cause,
  44                 0,
  45                 &mut obligations,
  46             );
  47             fulfill_cx.register_predicate_obligations(infcx, obligations);
  48             Ok(NormalizationResult {
  49                 normalized_ty: answer,
  50             })
  51         },
  52     )
  53 }