Auto merge of rust-lang#14017 - lowr:patch/remove-type-walk, r=Veykril

internal: remove `TypeWalk`

Because less code is better!

`hir_ty::TypeWalk` is only used in analysis-stats and its usage can be replaced by checking `TypeFlags` (which is precomputed upon `TyKind` interning so it should make analysis-stats a bit faster, though it was really negligible in my local environment).

We should just use chalk's `TypeVisitor` or `TypeFolder` instead even if we come to need it again.

Author: bors

crates/hir-ty/src/lib.rs

@@ -20,7 +20,6 @@ mod lower;
 mod mapping;
 mod tls;
 mod utils;
-mod walk;
 pub mod db;
 pub mod diagnostics;
 pub mod display;
@@ -71,7 +70,6 @@ pub use mapping::{
 };
 pub use traits::TraitEnvironment;
 pub use utils::{all_super_traits, is_fn_unsafe_to_call};
-pub use walk::TypeWalk;
 
 pub use chalk_ir::{
     cast::Cast, AdtId, BoundVar, DebruijnIndex, Mutability, Safety, Scalar, TyVariableKind,
@@ -107,6 +105,7 @@ pub type GenericArgData = chalk_ir::GenericArgData<Interner>;
 
 pub type Ty = chalk_ir::Ty<Interner>;
 pub type TyKind = chalk_ir::TyKind<Interner>;
+pub type TypeFlags = chalk_ir::TypeFlags;
 pub type DynTy = chalk_ir::DynTy<Interner>;
 pub type FnPointer = chalk_ir::FnPointer<Interner>;
 // pub type FnSubst = chalk_ir::FnSubst<Interner>;

crates/hir-ty/src/walk.rs

@@ -3168,6 +3168,8 @@ impl Type {
     }
 
     pub fn contains_unknown(&self) -> bool {
+        // FIXME: When we get rid of `ConstScalar::Unknown`, we can just look at precomputed
+        // `TypeFlags` in `TyData`.
         return go(&self.ty);
 
         fn go(ty: &Ty) -> bool {
@@ -3482,10 +3484,9 @@ impl Type {
         Type { env: self.env.clone(), ty }
     }
 
+    /// Visits every type, including generic arguments, in this type. `cb` is called with type
+    /// itself first, and then with its generic arguments.
     pub fn walk(&self, db: &dyn HirDatabase, mut cb: impl FnMut(Type)) {
-        // TypeWalk::walk for a Ty at first visits parameters and only after that the Ty itself.
-        // We need a different order here.
-
         fn walk_substs(
             db: &dyn HirDatabase,
             type_: &Type,

crates/hir/src/lib.rs

@@ -15,7 +15,7 @@ use hir_def::{
     expr::ExprId,
     FunctionId,
 };
-use hir_ty::{TyExt, TypeWalk};
+use hir_ty::{Interner, TyExt, TypeFlags};
 use ide::{Analysis, AnalysisHost, LineCol, RootDatabase};
 use ide_db::base_db::{
     salsa::{self, debug::DebugQueryTable, ParallelDatabase},
@@ -280,12 +280,8 @@ impl flags::AnalysisStats {
                     }
                     true
                 } else {
-                    let mut is_partially_unknown = false;
-                    ty.walk(&mut |ty| {
-                        if ty.is_unknown() {
-                            is_partially_unknown = true;
-                        }
-                    });
+                    let is_partially_unknown =
+                        ty.data(Interner).flags.contains(TypeFlags::HAS_ERROR);
                     if is_partially_unknown {
                         num_exprs_partially_unknown += 1;
                     }