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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, '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_obligation_recursively(&obligation)
},
)
}
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