| // Copyright 2018 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use rustc::traits::{EvaluationResult, Obligation, ObligationCause, |
| OverflowError, SelectionContext, TraitQueryMode}; |
| use rustc::traits::query::CanonicalPredicateGoal; |
| use rustc::ty::query::Providers; |
| use rustc::ty::{ParamEnvAnd, TyCtxt}; |
| use syntax::codemap::DUMMY_SP; |
| |
| crate fn provide(p: &mut Providers) { |
| *p = Providers { |
| evaluate_obligation, |
| ..*p |
| }; |
| } |
| |
| fn evaluate_obligation<'tcx>( |
| tcx: TyCtxt<'_, 'tcx, 'tcx>, |
| goal: CanonicalPredicateGoal<'tcx>, |
| ) -> Result<EvaluationResult, OverflowError> { |
| tcx.infer_ctxt().enter(|ref infcx| { |
| let ( |
| ParamEnvAnd { |
| param_env, |
| value: predicate, |
| }, |
| _canonical_inference_vars, |
| ) = infcx.instantiate_canonical_with_fresh_inference_vars(DUMMY_SP, &goal); |
| |
| let mut selcx = SelectionContext::with_query_mode(&infcx, TraitQueryMode::Canonical); |
| let obligation = Obligation::new(ObligationCause::dummy(), param_env, predicate); |
| |
| selcx.evaluate_obligation_recursively(&obligation) |
| }) |
| } |