Convert `TypeVisitor` and `DefIdVisitor` to use `VisitorResult`

7 files changed, 67 insertions, 100 deletions

diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs
index 712fbf24440..2506456f1fb 100644
--- a/compiler/rustc_middle/src/ty/diagnostics.rs
+++ b/compiler/rustc_middle/src/ty/diagnostics.rs
@@ -482,9 +482,9 @@ pub struct IsSuggestableVisitor<'tcx> {
 }
 
 impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for IsSuggestableVisitor<'tcx> {
-    type BreakTy = ();
+    type Result = ControlFlow<()>;
 
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
         match *t.kind() {
             Infer(InferTy::TyVar(_)) if self.infer_suggestable => {}
 
@@ -536,7 +536,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for IsSuggestableVisitor<'tcx> {
         t.super_visit_with(self)
     }
 
-    fn visit_const(&mut self, c: Const<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_const(&mut self, c: Const<'tcx>) -> Self::Result {
         match c.kind() {
             ConstKind::Infer(InferConst::Var(_)) if self.infer_suggestable => {}
 
diff --git a/compiler/rustc_middle/src/ty/generic_args.rs b/compiler/rustc_middle/src/ty/generic_args.rs
index c87ef870a08..8079ad121ad 100644
--- a/compiler/rustc_middle/src/ty/generic_args.rs
+++ b/compiler/rustc_middle/src/ty/generic_args.rs
@@ -6,6 +6,8 @@ use crate::ty::sty::{ClosureArgs, CoroutineArgs, CoroutineClosureArgs, InlineCon
 use crate::ty::visit::{TypeVisitable, TypeVisitableExt, TypeVisitor};
 use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt};
 
+use rustc_ast_ir::visit::VisitorResult;
+use rustc_ast_ir::walk_visitable_list;
 use rustc_data_structures::intern::Interned;
 use rustc_errors::{DiagArgValue, IntoDiagnosticArg};
 use rustc_hir::def_id::DefId;
@@ -19,7 +21,7 @@ use std::cmp::Ordering;
 use std::marker::PhantomData;
 use std::mem;
 use std::num::NonZero;
-use std::ops::{ControlFlow, Deref};
+use std::ops::Deref;
 use std::ptr::NonNull;
 
 /// An entity in the Rust type system, which can be one of
@@ -240,7 +242,7 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for GenericArg<'tcx> {
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for GenericArg<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         match self.unpack() {
             GenericArgKind::Lifetime(lt) => lt.visit_with(visitor),
             GenericArgKind::Type(ty) => ty.visit_with(visitor),
@@ -554,8 +556,9 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<Ty<'tcx>> {
 
 impl<'tcx, T: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>> for &'tcx ty::List<T> {
     #[inline]
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        self.iter().try_for_each(|t| t.visit_with(visitor))
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
+        walk_visitable_list!(visitor, self.iter());
+        V::Result::output()
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index c6bb7032ace..0a38d379a52 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -33,7 +33,7 @@ pub use generics::*;
 pub use intrinsic::IntrinsicDef;
 use rustc_ast as ast;
 use rustc_ast::node_id::NodeMap;
-pub use rustc_ast_ir::{Movability, Mutability};
+pub use rustc_ast_ir::{try_visit, Movability, Mutability};
 use rustc_attr as attr;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::intern::Interned;
@@ -64,7 +64,6 @@ use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem;
 use std::num::NonZero;
-use std::ops::ControlFlow;
 use std::ptr::NonNull;
 use std::{fmt, str};
 
@@ -599,7 +598,7 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Term<'tcx> {
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Term<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         self.unpack().visit_with(visitor)
     }
 }
@@ -1043,8 +1042,8 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ParamEnv<'tcx> {
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ParamEnv<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        self.caller_bounds().visit_with(visitor)?;
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
+        try_visit!(self.caller_bounds().visit_with(visitor));
         self.reveal().visit_with(visitor)
     }
 }
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 540803d9530..c8c9afa7f4d 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -27,7 +27,7 @@ use std::cell::Cell;
 use std::collections::BTreeMap;
 use std::fmt::{self, Write as _};
 use std::iter;
-use std::ops::{ControlFlow, Deref, DerefMut};
+use std::ops::{Deref, DerefMut};
 
 // `pretty` is a separate module only for organization.
 use super::*;
@@ -2667,9 +2667,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
         }
 
         impl<'tcx> ty::visit::TypeVisitor<TyCtxt<'tcx>> for RegionNameCollector<'tcx> {
-            type BreakTy = ();
-
-            fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+            fn visit_region(&mut self, r: ty::Region<'tcx>) {
                 trace!("address: {:p}", r.0.0);
 
                 // Collect all named lifetimes. These allow us to prevent duplication
@@ -2678,18 +2676,14 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                 if let Some(name) = r.get_name() {
                     self.used_region_names.insert(name);
                 }
-
-                ControlFlow::Continue(())
             }
 
             // We collect types in order to prevent really large types from compiling for
             // a really long time. See issue #83150 for why this is necessary.
-            fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+            fn visit_ty(&mut self, ty: Ty<'tcx>) {
                 let not_previously_inserted = self.type_collector.insert(ty);
                 if not_previously_inserted {
                     ty.super_visit_with(self)
-                } else {
-                    ControlFlow::Continue(())
                 }
             }
         }
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index c6805ba9323..c8fb11673cf 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -8,13 +8,14 @@ use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
 use crate::ty::print::{with_no_trimmed_paths, FmtPrinter, Printer};
 use crate::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
 use crate::ty::{self, AliasTy, InferConst, Lift, Term, TermKind, Ty, TyCtxt};
+use rustc_ast_ir::try_visit;
+use rustc_ast_ir::visit::VisitorResult;
 use rustc_hir::def::Namespace;
 use rustc_span::source_map::Spanned;
 use rustc_target::abi::TyAndLayout;
 use rustc_type_ir::{ConstKind, DebugWithInfcx, InferCtxtLike, WithInfcx};
 
 use std::fmt::{self, Debug};
-use std::ops::ControlFlow;
 
 use super::print::PrettyPrinter;
 use super::{GenericArg, GenericArgKind, Region};
@@ -482,11 +483,8 @@ impl<'a, 'tcx> Lift<'tcx> for Term<'a> {
 // Traversal implementations.
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::AdtDef<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
-        &self,
-        _visitor: &mut V,
-    ) -> ControlFlow<V::BreakTy> {
-        ControlFlow::Continue(())
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, _visitor: &mut V) -> V::Result {
+        V::Result::output()
     }
 }
 
@@ -500,7 +498,7 @@ impl<'tcx, T: TypeFoldable<TyCtxt<'tcx>>> TypeFoldable<TyCtxt<'tcx>> for ty::Bin
 }
 
 impl<'tcx, T: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>> for ty::Binder<'tcx, T> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         visitor.visit_binder(self)
     }
 }
@@ -517,10 +515,7 @@ impl<'tcx, T: TypeFoldable<TyCtxt<'tcx>>> TypeSuperFoldable<TyCtxt<'tcx>> for ty
 impl<'tcx, T: TypeVisitable<TyCtxt<'tcx>>> TypeSuperVisitable<TyCtxt<'tcx>>
     for ty::Binder<'tcx, T>
 {
-    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
-        &self,
-        visitor: &mut V,
-    ) -> ControlFlow<V::BreakTy> {
+    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         self.as_ref().skip_binder().visit_with(visitor)
     }
 }
@@ -553,7 +548,7 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Ty<'tcx> {
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Ty<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         visitor.visit_ty(*self)
     }
 }
@@ -609,27 +604,24 @@ impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for Ty<'tcx> {
 }
 
 impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for Ty<'tcx> {
-    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
-        &self,
-        visitor: &mut V,
-    ) -> ControlFlow<V::BreakTy> {
+    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         match self.kind() {
             ty::RawPtr(ref tm) => tm.visit_with(visitor),
             ty::Array(typ, sz) => {
-                typ.visit_with(visitor)?;
+                try_visit!(typ.visit_with(visitor));
                 sz.visit_with(visitor)
             }
             ty::Slice(typ) => typ.visit_with(visitor),
             ty::Adt(_, args) => args.visit_with(visitor),
             ty::Dynamic(ref trait_ty, ref reg, _) => {
-                trait_ty.visit_with(visitor)?;
+                try_visit!(trait_ty.visit_with(visitor));
                 reg.visit_with(visitor)
             }
             ty::Tuple(ts) => ts.visit_with(visitor),
             ty::FnDef(_, args) => args.visit_with(visitor),
             ty::FnPtr(ref f) => f.visit_with(visitor),
             ty::Ref(r, ty, _) => {
-                r.visit_with(visitor)?;
+                try_visit!(r.visit_with(visitor));
                 ty.visit_with(visitor)
             }
             ty::Coroutine(_did, ref args) => args.visit_with(visitor),
@@ -650,7 +642,7 @@ impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for Ty<'tcx> {
             | ty::Placeholder(..)
             | ty::Param(..)
             | ty::Never
-            | ty::Foreign(..) => ControlFlow::Continue(()),
+            | ty::Foreign(..) => V::Result::output(),
         }
     }
 }
@@ -665,7 +657,7 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Region<'tcx> {
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::Region<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         visitor.visit_region(*self)
     }
 }
@@ -690,13 +682,13 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Clause<'tcx> {
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::Predicate<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         visitor.visit_predicate(*self)
     }
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::Clause<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         visitor.visit_predicate(self.as_predicate())
     }
 }
@@ -712,10 +704,7 @@ impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for ty::Predicate<'tcx> {
 }
 
 impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for ty::Predicate<'tcx> {
-    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
-        &self,
-        visitor: &mut V,
-    ) -> ControlFlow<V::BreakTy> {
+    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         self.kind().visit_with(visitor)
     }
 }
@@ -739,7 +728,7 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Const<'tcx> {
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::Const<'tcx> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         visitor.visit_const(*self)
     }
 }
@@ -771,16 +760,13 @@ impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for ty::Const<'tcx> {
 }
 
 impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for ty::Const<'tcx> {
-    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
-        &self,
-        visitor: &mut V,
-    ) -> ControlFlow<V::BreakTy> {
-        self.ty().visit_with(visitor)?;
+    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
+        try_visit!(self.ty().visit_with(visitor));
         match self.kind() {
             ConstKind::Param(p) => p.visit_with(visitor),
             ConstKind::Infer(i) => i.visit_with(visitor),
             ConstKind::Bound(d, b) => {
-                d.visit_with(visitor)?;
+                try_visit!(d.visit_with(visitor));
                 b.visit_with(visitor)
             }
             ConstKind::Placeholder(p) => p.visit_with(visitor),
@@ -802,25 +788,19 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for InferConst {
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for InferConst {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
-        &self,
-        _visitor: &mut V,
-    ) -> ControlFlow<V::BreakTy> {
-        ControlFlow::Continue(())
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, _visitor: &mut V) -> V::Result {
+        V::Result::output()
     }
 }
 
 impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for ty::UnevaluatedConst<'tcx> {
-    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
-        &self,
-        visitor: &mut V,
-    ) -> ControlFlow<V::BreakTy> {
+    fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         self.args.visit_with(visitor)
     }
 }
 
 impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for TyAndLayout<'tcx, Ty<'tcx>> {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
         visitor.visit_ty(self.ty)
     }
 }
@@ -828,10 +808,9 @@ impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for TyAndLayout<'tcx, Ty<'tcx>> {
 impl<'tcx, T: TypeVisitable<TyCtxt<'tcx>> + Debug + Clone> TypeVisitable<TyCtxt<'tcx>>
     for Spanned<T>
 {
-    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        self.node.visit_with(visitor)?;
-        self.span.visit_with(visitor)?;
-        ControlFlow::Continue(())
+    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
+        try_visit!(self.node.visit_with(visitor));
+        self.span.visit_with(visitor)
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 17659ac2330..4b349e7836c 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -2113,9 +2113,9 @@ impl<'tcx> Ty<'tcx> {
         struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
 
         impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsTyVisitor<'tcx> {
-            type BreakTy = ();
+            type Result = ControlFlow<()>;
 
-            fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+            fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
                 if self.0 == t { ControlFlow::Break(()) } else { t.super_visit_with(self) }
             }
         }
@@ -2131,9 +2131,9 @@ impl<'tcx> Ty<'tcx> {
         struct ContainsClosureVisitor;
 
         impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsClosureVisitor {
-            type BreakTy = ();
+            type Result = ControlFlow<()>;
 
-            fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+            fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
                 if let ty::Closure(..) = t.kind() {
                     ControlFlow::Break(())
                 } else {
diff --git a/compiler/rustc_middle/src/ty/visit.rs b/compiler/rustc_middle/src/ty/visit.rs
index 59d09c3dc78..218567bbd59 100644
--- a/compiler/rustc_middle/src/ty/visit.rs
+++ b/compiler/rustc_middle/src/ty/visit.rs
@@ -64,19 +64,19 @@ impl<'tcx> TyCtxt<'tcx> {
         where
             F: FnMut(ty::Region<'tcx>) -> bool,
         {
-            type BreakTy = ();
+            type Result = ControlFlow<()>;
 
             fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
                 &mut self,
                 t: &Binder<'tcx, T>,
-            ) -> ControlFlow<Self::BreakTy> {
+            ) -> Self::Result {
                 self.outer_index.shift_in(1);
                 let result = t.super_visit_with(self);
                 self.outer_index.shift_out(1);
                 result
             }
 
-            fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+            fn visit_region(&mut self, r: ty::Region<'tcx>) -> Self::Result {
                 match *r {
                     ty::ReBound(debruijn, _) if debruijn < self.outer_index => {
                         ControlFlow::Continue(())
@@ -91,7 +91,7 @@ impl<'tcx> TyCtxt<'tcx> {
                 }
             }
 
-            fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+            fn visit_ty(&mut self, ty: Ty<'tcx>) -> Self::Result {
                 // We're only interested in types involving regions
                 if ty.flags().intersects(TypeFlags::HAS_FREE_REGIONS) {
                     ty.super_visit_with(self)
@@ -140,8 +140,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let mut collector = LateBoundRegionsCollector::new(just_constrained);
         let value = value.skip_binder();
         let value = if just_constrained { self.expand_weak_alias_tys(value) } else { value };
-        let result = value.visit_with(&mut collector);
-        assert!(result.is_continue()); // should never have stopped early
+        value.visit_with(&mut collector);
         collector.regions
     }
 }
@@ -165,19 +164,19 @@ impl<'tcx> ValidateBoundVars<'tcx> {
 }
 
 impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ValidateBoundVars<'tcx> {
-    type BreakTy = ();
+    type Result = ControlFlow<()>;
 
     fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
         &mut self,
         t: &Binder<'tcx, T>,
-    ) -> ControlFlow<Self::BreakTy> {
+    ) -> Self::Result {
         self.binder_index.shift_in(1);
         let result = t.super_visit_with(self);
         self.binder_index.shift_out(1);
         result
     }
 
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
         if t.outer_exclusive_binder() < self.binder_index
             || !self.visited.insert((self.binder_index, t))
         {
@@ -211,7 +210,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ValidateBoundVars<'tcx> {
         t.super_visit_with(self)
     }
 
-    fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_region(&mut self, r: ty::Region<'tcx>) -> Self::Result {
         match *r {
             ty::ReBound(index, br) if index == self.binder_index => {
                 if self.bound_vars.len() <= br.var.as_usize() {
@@ -266,23 +265,19 @@ impl LateBoundRegionsCollector {
 }
 
 impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for LateBoundRegionsCollector {
-    fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
-        &mut self,
-        t: &Binder<'tcx, T>,
-    ) -> ControlFlow<Self::BreakTy> {
+    fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(&mut self, t: &Binder<'tcx, T>) {
         self.current_index.shift_in(1);
-        let result = t.super_visit_with(self);
+        t.super_visit_with(self);
         self.current_index.shift_out(1);
-        result
     }
 
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_ty(&mut self, t: Ty<'tcx>) {
         if self.just_constrained {
             match t.kind() {
                 // If we are only looking for "constrained" regions, we have to ignore the
                 // inputs to a projection as they may not appear in the normalized form.
                 ty::Alias(ty::Projection | ty::Inherent | ty::Opaque, _) => {
-                    return ControlFlow::Continue(());
+                    return;
                 }
                 // All weak alias types should've been expanded beforehand.
                 ty::Alias(ty::Weak, _) => bug!("unexpected weak alias type"),
@@ -293,26 +288,25 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for LateBoundRegionsCollector {
         t.super_visit_with(self)
     }
 
-    fn visit_const(&mut self, c: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_const(&mut self, c: ty::Const<'tcx>) {
         // if we are only looking for "constrained" region, we have to
         // ignore the inputs of an unevaluated const, as they may not appear
         // in the normalized form
         if self.just_constrained {
             if let ty::ConstKind::Unevaluated(..) = c.kind() {
-                return ControlFlow::Continue(());
+                return;
             }
         }
 
         c.super_visit_with(self)
     }
 
-    fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_region(&mut self, r: ty::Region<'tcx>) {
         if let ty::ReBound(debruijn, br) = *r {
             if debruijn == self.current_index {
                 self.regions.insert(br.kind);
             }
         }
-        ControlFlow::Continue(())
     }
 }
 
@@ -332,7 +326,7 @@ impl MaxUniverse {
 }
 
 impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for MaxUniverse {
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_ty(&mut self, t: Ty<'tcx>) {
         if let ty::Placeholder(placeholder) = t.kind() {
             self.max_universe = ty::UniverseIndex::from_u32(
                 self.max_universe.as_u32().max(placeholder.universe.as_u32()),
@@ -342,7 +336,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for MaxUniverse {
         t.super_visit_with(self)
     }
 
-    fn visit_const(&mut self, c: ty::consts::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_const(&mut self, c: ty::consts::Const<'tcx>) {
         if let ty::ConstKind::Placeholder(placeholder) = c.kind() {
             self.max_universe = ty::UniverseIndex::from_u32(
                 self.max_universe.as_u32().max(placeholder.universe.as_u32()),
@@ -352,13 +346,11 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for MaxUniverse {
         c.super_visit_with(self)
     }
 
-    fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+    fn visit_region(&mut self, r: ty::Region<'tcx>) {
         if let ty::RePlaceholder(placeholder) = *r {
             self.max_universe = ty::UniverseIndex::from_u32(
                 self.max_universe.as_u32().max(placeholder.universe.as_u32()),
             );
         }
-
-        ControlFlow::Continue(())
     }
 }