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Unconstrained terms should account for infer vars being equated #108879

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merged 1 commit into from
Mar 10, 2023
+20 −15
Merged

Unconstrained terms should account for infer vars being equated #108879

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35 changes: 20 additions & 15 deletions compiler/rustc_trait_selection/src/solve/eval_ctxt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -93,37 +93,42 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
};

// Guard against `<T as Trait<?0>>::Assoc = ?0>`.
struct ContainsTerm<'tcx> {
struct ContainsTerm<'a, 'tcx> {
term: ty::Term<'tcx>,
infcx: &'a InferCtxt<'tcx>,
}
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsTerm<'tcx> {
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsTerm<'_, 'tcx> {
type BreakTy = ();
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
if t.needs_infer() {
if ty::Term::from(t) == self.term {
ControlFlow::Break(())
} else {
t.super_visit_with(self)
}
if let Some(vid) = t.ty_vid()
&& let ty::TermKind::Ty(term) = self.term.unpack()
&& let Some(term_vid) = term.ty_vid()
&& self.infcx.root_var(vid) == self.infcx.root_var(term_vid)
{
ControlFlow::Break(())
} else if t.has_non_region_infer() {
t.super_visit_with(self)
} else {
ControlFlow::Continue(())
}
}

fn visit_const(&mut self, c: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
if c.needs_infer() {
if ty::Term::from(c) == self.term {
ControlFlow::Break(())
} else {
c.super_visit_with(self)
}
if let ty::ConstKind::Infer(ty::InferConst::Var(vid)) = c.kind()
&& let ty::TermKind::Const(term) = self.term.unpack()
&& let ty::ConstKind::Infer(ty::InferConst::Var(term_vid)) = term.kind()
&& self.infcx.root_const_var(vid) == self.infcx.root_const_var(term_vid)
{
ControlFlow::Break(())
} else if c.has_non_region_infer() {
c.super_visit_with(self)
} else {
ControlFlow::Continue(())
}
}
}

let mut visitor = ContainsTerm { term: goal.predicate.term };
let mut visitor = ContainsTerm { infcx: self.infcx, term: goal.predicate.term };

term_is_infer
&& goal.predicate.projection_ty.visit_with(&mut visitor).is_continue()
Expand Down