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use rustc::infer::canonical::{Canonical, QueryResult};
use rustc::traits::{self, FulfillmentContext, Normalized, ObligationCause,
SelectionContext};
use rustc::traits::query::{CanonicalProjectionGoal, NoSolution, normalize::NormalizationResult};
use rustc::ty::{ParamEnvAnd, TyCtxt};
use rustc_data_structures::sync::Lrc;
use syntax::ast::DUMMY_NODE_ID;
use syntax_pos::DUMMY_SP;
use util;
use std::sync::atomic::Ordering;
crate fn normalize_projection_ty<'tcx>(
tcx: TyCtxt<'_, 'tcx, 'tcx>,
goal: CanonicalProjectionGoal<'tcx>,
) -> Result<Lrc<Canonical<'tcx, QueryResult<'tcx, NormalizationResult<'tcx>>>>, NoSolution> {
debug!("normalize_provider(goal={:#?})", goal);
tcx.sess.perf_stats.normalize_projection_ty.fetch_add(1, Ordering::Relaxed);
tcx.infer_ctxt().enter(|ref infcx| {
let (
ParamEnvAnd {
param_env,
value: goal,
},
canonical_inference_vars,
) = infcx.instantiate_canonical_with_fresh_inference_vars(DUMMY_SP, &goal);
let fulfill_cx = &mut FulfillmentContext::new();
let selcx = &mut SelectionContext::new(infcx);
let cause = ObligationCause::misc(DUMMY_SP, DUMMY_NODE_ID);
let Normalized {
value: answer,
obligations,
} = traits::normalize_projection_type(selcx, param_env, goal, cause, 0);
fulfill_cx.register_predicate_obligations(infcx, obligations);
util::make_query_response(
infcx,
canonical_inference_vars,
NormalizationResult { normalized_ty: answer },
fulfill_cx,
)
})
}