Move visitor utils to rustc_ast_ir

compiler/rustc_ast/src/visit.rs

@@ -15,11 +15,12 @@
 
 use crate::ast::*;
 
-use core::ops::ControlFlow;
-
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
 
+pub use rustc_ast_ir::visit::VisitorResult;
+pub use rustc_ast_ir::{try_visit, visit_opt, walk_list, walk_visitable_list};
+
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub enum AssocCtxt {
     Trait,
@@ -101,51 +102,6 @@ pub enum LifetimeCtxt {
     GenericArg,
 }
 
-/// Similar to the `Try` trait, but also implemented for `()`.
-pub trait VisitorResult {
-    type Residual;
-    fn output() -> Self;
-    fn from_residual(residual: Self::Residual) -> Self;
-    fn branch(self) -> ControlFlow<Self::Residual>;
-}
-
-impl VisitorResult for () {
-    type Residual = !;
-
-    fn output() -> Self {}
-    fn from_residual(_: !) -> Self {}
-    fn branch(self) -> ControlFlow<!> {
-        ControlFlow::Continue(())
-    }
-}
-
-impl<T> VisitorResult for ControlFlow<T> {
-    type Residual = T;
-
-    fn output() -> Self {
-        ControlFlow::Continue(())
-    }
-    fn from_residual(residual: Self::Residual) -> Self {
-        ControlFlow::Break(residual)
-    }
-    fn branch(self) -> ControlFlow<T> {
-        self
-    }
-}
-
-#[macro_export]
-macro_rules! try_visit {
-    ($e:expr) => {
-        match $crate::visit::VisitorResult::branch($e) {
-            core::ops::ControlFlow::Continue(()) => (),
-            #[allow(unreachable_code)]
-            core::ops::ControlFlow::Break(r) => {
-                return $crate::visit::VisitorResult::from_residual(r);
-            }
-        }
-    };
-}
-
 /// Each method of the `Visitor` trait is a hook to be potentially
 /// overridden. Each method's default implementation recursively visits
 /// the substructure of the input via the corresponding `walk` method;
@@ -316,24 +272,6 @@ pub trait Visitor<'ast>: Sized {
     }
 }
 
-#[macro_export]
-macro_rules! walk_list {
-    ($visitor: expr, $method: ident, $list: expr $(, $($extra_args: expr),* )?) => {
-        for elem in $list {
-            $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
-        }
-    }
-}
-
-#[macro_export]
-macro_rules! visit_opt {
-    ($visitor: expr, $method: ident, $opt: expr $(, $($extra_args: expr),* )?) => {
-        if let Some(x) = $opt {
-            $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
-        }
-    }
-}
-
 pub fn walk_crate<'a, V: Visitor<'a>>(visitor: &mut V, krate: &'a Crate) -> V::Result {
     walk_list!(visitor, visit_item, &krate.items);
     walk_list!(visitor, visit_attribute, &krate.attrs);

compiler/rustc_ast_ir/src/lib.rs

@@ -1,3 +1,4 @@
+#![cfg_attr(feature = "nightly", feature(never_type))]
 #![cfg_attr(feature = "nightly", feature(rustc_attrs))]
 #![cfg_attr(feature = "nightly", allow(internal_features))]
 
@@ -5,6 +6,8 @@
 #[macro_use]
 extern crate rustc_macros;
 
+pub mod visit;
+
 /// The movability of a coroutine / closure literal:
 /// whether a coroutine contains self-references, causing it to be `!Unpin`.
 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Copy)]

compiler/rustc_ast_ir/src/visit.rs

@@ -0,0 +1,82 @@
+use core::ops::ControlFlow;
+
+/// Similar to the `Try` trait, but also implemented for `()`.
+pub trait VisitorResult {
+    type Residual;
+    fn output() -> Self;
+    fn from_residual(residual: Self::Residual) -> Self;
+    fn from_branch(b: ControlFlow<Self::Residual>) -> Self;
+    fn branch(self) -> ControlFlow<Self::Residual>;
+}
+
+impl VisitorResult for () {
+    #[cfg(feature = "nightly")]
+    type Residual = !;
+
+    #[cfg(not(feature = "nightly"))]
+    type Residual = core::ops::Infallible;
+
+    fn output() -> Self {}
+    fn from_residual(_: Self::Residual) -> Self {}
+    fn from_branch(_: ControlFlow<Self::Residual>) -> Self {}
+    fn branch(self) -> ControlFlow<Self::Residual> {
+        ControlFlow::Continue(())
+    }
+}
+
+impl<T> VisitorResult for ControlFlow<T> {
+    type Residual = T;
+
+    fn output() -> Self {
+        ControlFlow::Continue(())
+    }
+    fn from_residual(residual: Self::Residual) -> Self {
+        ControlFlow::Break(residual)
+    }
+    fn from_branch(b: Self) -> Self {
+        b
+    }
+    fn branch(self) -> Self {
+        self
+    }
+}
+
+#[macro_export]
+macro_rules! try_visit {
+    ($e:expr) => {
+        match $crate::visit::VisitorResult::branch($e) {
+            core::ops::ControlFlow::Continue(()) => (),
+            #[allow(unreachable_code)]
+            core::ops::ControlFlow::Break(r) => {
+                return $crate::visit::VisitorResult::from_residual(r);
+            }
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! visit_opt {
+    ($visitor: expr, $method: ident, $opt: expr $(, $($extra_args: expr),* )?) => {
+        if let Some(x) = $opt {
+            $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
+        }
+    }
+}
+
+#[macro_export]
+macro_rules! walk_list {
+    ($visitor: expr, $method: ident, $list: expr $(, $($extra_args: expr),* )?) => {
+        for elem in $list {
+            $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
+        }
+    }
+}
+
+#[macro_export]
+macro_rules! walk_visitable_list {
+    ($visitor: expr, $list: expr $(, $($extra_args: expr),* )?) => {
+        for elem in $list {
+            $crate::try_visit!(elem.visit_with($visitor $(, $($extra_args,)* )?));
+        }
+    }
+}

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -8,8 +8,7 @@
 
 use itertools::{Either, Itertools};
 use rustc_ast::ptr::P;
-use rustc_ast::visit::{AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
-use rustc_ast::walk_list;
+use rustc_ast::visit::{walk_list, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
 use rustc_ast::*;
 use rustc_ast_pretty::pprust::{self, State};
 use rustc_data_structures::fx::FxIndexMap;

compiler/rustc_builtin_macros/src/deriving/default.rs

@@ -2,7 +2,8 @@ use crate::deriving::generic::ty::*;
 use crate::deriving::generic::*;
 use crate::errors;
 use rustc_ast as ast;
-use rustc_ast::{attr, walk_list, EnumDef, VariantData};
+use rustc_ast::visit::walk_list;
+use rustc_ast::{attr, EnumDef, VariantData};
 use rustc_expand::base::{Annotatable, DummyResult, ExtCtxt};
 use rustc_span::symbol::Ident;
 use rustc_span::symbol::{kw, sym};

compiler/rustc_expand/src/expand.rs

@@ -14,8 +14,7 @@ use rustc_ast::mut_visit::*;
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter};
 use rustc_ast::tokenstream::TokenStream;
-use rustc_ast::visit::{self, AssocCtxt, Visitor, VisitorResult};
-use rustc_ast::{try_visit, walk_list};
+use rustc_ast::visit::{self, try_visit, walk_list, AssocCtxt, Visitor, VisitorResult};
 use rustc_ast::{AssocItemKind, AstNodeWrapper, AttrArgs, AttrStyle, AttrVec, ExprKind};
 use rustc_ast::{ForeignItemKind, HasAttrs, HasNodeId};
 use rustc_ast::{Inline, ItemKind, MacStmtStyle, MetaItemKind, ModKind};

compiler/rustc_hir/src/intravisit.rs

@@ -65,8 +65,7 @@
 //! example coroutine inference, and possibly also HIR borrowck.
 
 use crate::hir::*;
-use rustc_ast::visit::VisitorResult;
-use rustc_ast::{try_visit, visit_opt, walk_list};
+use rustc_ast::visit::{try_visit, visit_opt, walk_list, VisitorResult};
 use rustc_ast::{Attribute, Label};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::symbol::{Ident, Symbol};

compiler/rustc_hir_analysis/src/check/region.rs

@@ -6,7 +6,7 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/borrow_check.html
 
-use rustc_ast::walk_list;
+use rustc_ast::visit::walk_list;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;

compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs

@@ -6,7 +6,7 @@
 //! the types in HIR to identify late-bound lifetimes and assign their Debruijn indices. This file
 //! is also responsible for assigning their semantics to implicit lifetimes in trait objects.
 
-use rustc_ast::walk_list;
+use rustc_ast::visit::walk_list;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_errors::{codes::*, struct_span_code_err};
 use rustc_hir as hir;

compiler/rustc_lint/src/early.rs

@@ -17,8 +17,8 @@
 use crate::context::{EarlyContext, LintContext, LintStore};
 use crate::passes::{EarlyLintPass, EarlyLintPassObject};
 use rustc_ast::ptr::P;
-use rustc_ast::visit::{self as ast_visit, Visitor};
-use rustc_ast::{self as ast, walk_list, HasAttrs};
+use rustc_ast::visit::{self as ast_visit, walk_list, Visitor};
+use rustc_ast::{self as ast, HasAttrs};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_feature::Features;
 use rustc_middle::ty::RegisteredTools;

compiler/rustc_middle/src/hir/map/mod.rs

@@ -3,8 +3,7 @@ use crate::middle::debugger_visualizer::DebuggerVisualizerFile;
 use crate::query::LocalCrate;
 use crate::ty::TyCtxt;
 use rustc_ast as ast;
-use rustc_ast::visit::VisitorResult;
-use rustc_ast::walk_list;
+use rustc_ast::visit::{walk_list, VisitorResult};
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::svh::Svh;

compiler/rustc_resolve/src/late.rs

@@ -13,7 +13,7 @@ use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
 use crate::{ResolutionError, Resolver, Segment, UseError};
 
 use rustc_ast::ptr::P;
-use rustc_ast::visit::{AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
+use rustc_ast::visit::{walk_list, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
 use rustc_ast::*;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
 use rustc_errors::{