| use rustc_infer::infer::TyCtxtInferExt; |
| use rustc_middle::query::Providers; |
| use rustc_middle::ty::{ParamEnvAnd, TyCtxt}; |
| use rustc_span::DUMMY_SP; |
| use rustc_trait_selection::traits::query::CanonicalPredicateGoal; |
| use rustc_trait_selection::traits::{ |
| EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode, |
| }; |
| |
| pub(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> { |
| assert!(!tcx.next_trait_solver_globally()); |
| debug!("evaluate_obligation(canonical_goal={:#?})", canonical_goal); |
| let (ref infcx, goal, _canonical_inference_vars) = |
| tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &canonical_goal); |
| debug!("evaluate_obligation: goal={:#?}", goal); |
| let ParamEnvAnd { param_env, value: predicate } = goal; |
| |
| let mut selcx = SelectionContext::with_query_mode(&infcx, TraitQueryMode::Canonical); |
| let obligation = Obligation::new(tcx, ObligationCause::dummy(), param_env, predicate); |
| |
| selcx.evaluate_root_obligation(&obligation) |
| } |