Move FlagComputation, PatternKind, and TypeWalker to rustc_type_ir

Author: jackh726

Diff for: compiler/rustc_middle/src/arena.rs

@@ -89,7 +89,6 @@ macro_rules! arena_types {
             [] name_set: rustc_data_structures::unord::UnordSet<rustc_span::Symbol>,
             [] autodiff_item: rustc_ast::expand::autodiff_attrs::AutoDiffItem,
             [] ordered_name_set: rustc_data_structures::fx::FxIndexSet<rustc_span::Symbol>,
-            [] pats: rustc_middle::ty::PatternKind<'tcx>,
             [] valtree: rustc_middle::ty::ValTreeKind<'tcx>,
 
             // Note that this deliberately duplicates items in the `rustc_hir::arena`,

Diff for: compiler/rustc_middle/src/ty/consts.rs

@@ -3,6 +3,7 @@ use std::borrow::Cow;
 use rustc_data_structures::intern::Interned;
 use rustc_error_messages::MultiSpan;
 use rustc_macros::HashStable;
+use rustc_type_ir::walk::TypeWalker;
 use rustc_type_ir::{self as ir, TypeFlags, WithCachedTypeInfo};
 
 use crate::ty::{self, Ty, TyCtxt};
@@ -243,4 +244,18 @@ impl<'tcx> Const<'tcx> {
     pub fn is_ct_infer(self) -> bool {
         matches!(self.kind(), ty::ConstKind::Infer(_))
     }
+
+    /// Iterator that walks `self` and any types reachable from
+    /// `self`, in depth-first order. Note that just walks the types
+    /// that appear in `self`, it does not descend into the fields of
+    /// structs or variants. For example:
+    ///
+    /// ```text
+    /// isize => { isize }
+    /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
+    /// [isize] => { [isize], isize }
+    /// ```
+    pub fn walk(self) -> TypeWalker<TyCtxt<'tcx>> {
+        TypeWalker::new(self.into())
+    }
 }

Diff for: compiler/rustc_middle/src/ty/context.rs

@@ -870,7 +870,7 @@ impl<'tcx> CtxtInterners<'tcx> {
         Ty(Interned::new_unchecked(
             self.type_
                 .intern(kind, |kind| {
-                    let flags = super::flags::FlagComputation::for_kind(&kind);
+                    let flags = ty::FlagComputation::<TyCtxt<'tcx>>::for_kind(&kind);
                     let stable_hash = self.stable_hash(&flags, sess, untracked, &kind);
 
                     InternedInSet(self.arena.alloc(WithCachedTypeInfo {
@@ -896,7 +896,7 @@ impl<'tcx> CtxtInterners<'tcx> {
         Const(Interned::new_unchecked(
             self.const_
                 .intern(kind, |kind: ty::ConstKind<'_>| {
-                    let flags = super::flags::FlagComputation::for_const_kind(&kind);
+                    let flags = ty::FlagComputation::<TyCtxt<'tcx>>::for_const_kind(&kind);
                     let stable_hash = self.stable_hash(&flags, sess, untracked, &kind);
 
                     InternedInSet(self.arena.alloc(WithCachedTypeInfo {
@@ -912,7 +912,7 @@ impl<'tcx> CtxtInterners<'tcx> {
 
     fn stable_hash<'a, T: HashStable<StableHashingContext<'a>>>(
         &self,
-        flags: &ty::flags::FlagComputation,
+        flags: &ty::FlagComputation<TyCtxt<'tcx>>,
         sess: &'a Session,
         untracked: &'a Untracked,
         val: &T,
@@ -940,7 +940,7 @@ impl<'tcx> CtxtInterners<'tcx> {
         Predicate(Interned::new_unchecked(
             self.predicate
                 .intern(kind, |kind| {
-                    let flags = super::flags::FlagComputation::for_predicate(kind);
+                    let flags = ty::FlagComputation::<TyCtxt<'tcx>>::for_predicate(kind);
 
                     let stable_hash = self.stable_hash(&flags, sess, untracked, &kind);
 
@@ -961,7 +961,7 @@ impl<'tcx> CtxtInterners<'tcx> {
         } else {
             self.clauses
                 .intern_ref(clauses, || {
-                    let flags = super::flags::FlagComputation::for_clauses(clauses);
+                    let flags = ty::FlagComputation::<TyCtxt<'tcx>>::for_clauses(clauses);
 
                     InternedInSet(ListWithCachedTypeInfo::from_arena(
                         &*self.arena,