| use rustc::traits::query::CanonicalPredicateGoal; |
| use rustc::traits::{ |
| EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode, |
| }; |
| use rustc::ty::query::Providers; |
| use rustc::ty::{ParamEnvAnd, TyCtxt}; |
| use syntax::source_map::DUMMY_SP; |
| |
| crate fn provide(p: &mut Providers<'_>) { |
| *p = Providers { |
| evaluate_obligation, |
| ..*p |
| }; |
| } |
| |
| fn evaluate_obligation<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| canonical_goal: CanonicalPredicateGoal<'tcx>, |
| ) -> Result<EvaluationResult, OverflowError> { |
| tcx.infer_ctxt().enter_with_canonical( |
| DUMMY_SP, |
| &canonical_goal, |
| |ref infcx, goal, _canonical_inference_vars| { |
| let ParamEnvAnd { |
| param_env, |
| value: predicate, |
| } = goal; |
| |
| let mut selcx = SelectionContext::with_query_mode(&infcx, TraitQueryMode::Canonical); |
| let obligation = Obligation::new(ObligationCause::dummy(), param_env, predicate); |
| |
| selcx.evaluate_root_obligation(&obligation) |
| }, |
| ) |
| } |