1 use rustc::ty::query::Providers;
2 use rustc::ty::{ParamEnvAnd, TyCtxt};
3 use rustc_infer::infer::TyCtxtInferExt;
4 use rustc_infer::traits::query::CanonicalPredicateGoal;
5 use rustc_infer::traits::{
6 EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode,
8 use rustc_span::source_map::DUMMY_SP;
10 crate fn provide(p: &mut Providers<'_>) {
11 *p = Providers { evaluate_obligation, ..*p };
14 fn evaluate_obligation<'tcx>(
16 canonical_goal: CanonicalPredicateGoal<'tcx>,
17 ) -> Result<EvaluationResult, OverflowError> {
18 debug!("evaluate_obligation(canonical_goal={:#?})", canonical_goal);
19 tcx.infer_ctxt().enter_with_canonical(
22 |ref infcx, goal, _canonical_inference_vars| {
23 debug!("evaluate_obligation: goal={:#?}", goal);
24 let ParamEnvAnd { param_env, value: predicate } = goal;
26 let mut selcx = SelectionContext::with_query_mode(&infcx, TraitQueryMode::Canonical);
27 let obligation = Obligation::new(ObligationCause::dummy(), param_env, predicate);
29 selcx.evaluate_root_obligation(&obligation)