use super::callee::DeferredCallResolution;
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_hir as hir;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::HirIdMap;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_span::def_id::LocalDefIdMap;
use rustc_span::{self, Span};
-use rustc_trait_selection::traits::{self, TraitEngine, TraitEngineExt as _};
+use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
+use rustc_trait_selection::traits::{self, PredicateObligation, TraitEngine, TraitEngineExt as _};
use std::cell::RefCell;
use std::ops::Deref;
/// we record that type variable here. This is later used to inform
/// fallback. See the `fallback` module for details.
pub(super) diverging_type_vars: RefCell<FxHashSet<Ty<'tcx>>>,
+
+ pub(super) infer_var_info: RefCell<FxHashMap<ty::TyVid, ty::InferVarInfo>>,
}
impl<'tcx> Deref for Inherited<'tcx> {
deferred_generator_interiors: RefCell::new(Vec::new()),
diverging_type_vars: RefCell::new(Default::default()),
body_id,
+ infer_var_info: RefCell::new(Default::default()),
}
}
if obligation.has_escaping_bound_vars() {
span_bug!(obligation.cause.span, "escaping bound vars in predicate {:?}", obligation);
}
+
+ self.update_infer_var_info(&obligation);
+
self.fulfillment_cx.borrow_mut().register_predicate_obligation(self, obligation);
}
self.register_predicates(infer_ok.obligations);
infer_ok.value
}
+
+ pub fn update_infer_var_info(&self, obligation: &PredicateObligation<'tcx>) {
+ let infer_var_info = &mut self.infer_var_info.borrow_mut();
+
+ // (*) binder skipped
+ if let ty::PredicateKind::Clause(ty::Clause::Trait(tpred)) = obligation.predicate.kind().skip_binder()
+ && let Some(ty) = self.shallow_resolve(tpred.self_ty()).ty_vid().map(|t| self.root_var(t))
+ && self.tcx.lang_items().sized_trait().map_or(false, |st| st != tpred.trait_ref.def_id)
+ {
+ let new_self_ty = self.tcx.types.unit;
+
+ // Then construct a new obligation with Self = () added
+ // to the ParamEnv, and see if it holds.
+ let o = obligation.with(self.tcx,
+ obligation
+ .predicate
+ .kind()
+ .rebind(
+ // (*) binder moved here
+ ty::PredicateKind::Clause(ty::Clause::Trait(tpred.with_self_ty(self.tcx, new_self_ty)))
+ ),
+ );
+ // Don't report overflow errors. Otherwise equivalent to may_hold.
+ if let Ok(result) = self.probe(|_| self.evaluate_obligation(&o)) && result.may_apply() {
+ infer_var_info.entry(ty).or_default().self_in_trait = true;
+ }
+ }
+
+ if let ty::PredicateKind::Clause(ty::Clause::Projection(predicate)) =
+ obligation.predicate.kind().skip_binder()
+ {
+ // If the projection predicate (Foo::Bar == X) has X as a non-TyVid,
+ // we need to make it into one.
+ if let Some(vid) = predicate.term.ty().and_then(|ty| ty.ty_vid()) {
+ debug!("infer_var_info: {:?}.output = true", vid);
+ infer_var_info.entry(vid).or_default().output = true;
+ }
+ }
+ }
}