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