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use dep_graph::{DepKind, DepTrackingMapConfig};
use std::marker::PhantomData;
use syntax_pos::DUMMY_SP;
use infer::InferCtxt;
use syntax_pos::Span;
use traits::{FulfillmentContext, Obligation, ObligationCause, SelectionContext,
TraitEngine, Vtable};
use ty::{self, Ty, TyCtxt};
use ty::subst::{Subst, Substs};
use ty::fold::TypeFoldable;
pub fn trans_fulfill_obligation<'a, 'tcx>(ty: TyCtxt<'a, 'tcx, 'tcx>,
(param_env, trait_ref):
(ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>))
-> Vtable<'tcx, ()>
{
let trait_ref = ty.erase_regions(&trait_ref);
debug!("trans::fulfill_obligation(trait_ref={:?}, def_id={:?})",
(param_env, trait_ref), trait_ref.def_id());
ty.infer_ctxt().enter(|infcx| {
let mut selcx = SelectionContext::new(&infcx);
let obligation_cause = ObligationCause::dummy();
let obligation = Obligation::new(obligation_cause,
param_env,
trait_ref.to_poly_trait_predicate());
let selection = match selcx.select(&obligation) {
Ok(Some(selection)) => selection,
Ok(None) => {
bug!("Encountered ambiguity selecting `{:?}` during trans, \
presuming due to overflow",
trait_ref)
}
Err(e) => {
bug!("Encountered error `{:?}` selecting `{:?}` during trans",
e, trait_ref)
}
};
debug!("fulfill_obligation: selection={:?}", selection);
let mut fulfill_cx = FulfillmentContext::new();
let vtable = selection.map(|predicate| {
debug!("fulfill_obligation: register_predicate_obligation {:?}", predicate);
fulfill_cx.register_predicate_obligation(&infcx, predicate);
});
let vtable = infcx.drain_fulfillment_cx_or_panic(DUMMY_SP, &mut fulfill_cx, &vtable);
info!("Cache miss: {:?} => {:?}", trait_ref, vtable);
vtable
})
}
impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> {
pub fn subst_and_normalize_erasing_regions<T>(
self,
param_substs: &Substs<'tcx>,
param_env: ty::ParamEnv<'tcx>,
value: &T
) -> T
where
T: TypeFoldable<'tcx>,
{
debug!(
"subst_and_normalize_erasing_regions(\
param_substs={:?}, \
value={:?}, \
param_env={:?})",
param_substs,
value,
param_env,
);
let substituted = value.subst(self, param_substs);
self.normalize_erasing_regions(param_env, substituted)
}
}
pub struct TraitSelectionCache<'tcx> {
data: PhantomData<&'tcx ()>
}
impl<'tcx> DepTrackingMapConfig for TraitSelectionCache<'tcx> {
type Key = (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>);
type Value = Vtable<'tcx, ()>;
fn to_dep_kind() -> DepKind {
DepKind::TraitSelect
}
}
pub struct ProjectionCache<'gcx> {
data: PhantomData<&'gcx ()>
}
impl<'gcx> DepTrackingMapConfig for ProjectionCache<'gcx> {
type Key = Ty<'gcx>;
type Value = Ty<'gcx>;
fn to_dep_kind() -> DepKind {
DepKind::TraitSelect
}
}
impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
fn drain_fulfillment_cx_or_panic<T>(&self,
span: Span,
fulfill_cx: &mut FulfillmentContext<'tcx>,
result: &T)
-> T::Lifted
where T: TypeFoldable<'tcx> + ty::Lift<'gcx>
{
debug!("drain_fulfillment_cx_or_panic()");
match fulfill_cx.select_all_or_error(self) {
Ok(()) => { }
Err(errors) => {
span_bug!(span, "Encountered errors `{:?}` resolving bounds after type-checking",
errors);
}
}
let result = self.resolve_type_vars_if_possible(result);
let result = self.tcx.erase_regions(&result);
match self.tcx.lift_to_global(&result) {
Some(result) => result,
None => {
span_bug!(span, "Uninferred types/regions in `{:?}`", result);
}
}
}
}