Make type walking infrastructure a bit nicer

If/when we switch to using Chalk's Ty, we'll need to replace this by its `Fold`
trait, but I didn't want to import the whole thing just yet.

6 files changed, 9 insertions, 19 deletions

diff --git a/crates/ra_hir/src/ty/autoderef.rs b/crates/ra_hir/src/ty/autoderef.rs
index 2535d4ae7..08f52a53b 100644
--- a/crates/ra_hir/src/ty/autoderef.rs
+++ b/crates/ra_hir/src/ty/autoderef.rs
@@ -7,7 +7,7 @@ use std::iter::successors;
 
 use log::{info, warn};
 
-use super::{traits::Solution, Canonical, Ty};
+use super::{traits::Solution, Canonical, Ty, TypeWalk};
 use crate::{HasGenericParams, HirDatabase, Name, Resolver};
 
 const AUTODEREF_RECURSION_LIMIT: usize = 10;
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index b89a40b4b..ec3b7ffef 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -30,7 +30,7 @@ use super::{
     autoderef, lower, method_resolution, op, primitive,
     traits::{Guidance, Obligation, ProjectionPredicate, Solution},
     ApplicationTy, CallableDef, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef,
-    Ty, TypableDef, TypeCtor,
+    Ty, TypableDef, TypeCtor, TypeWalk,
 };
 use crate::{
     adt::VariantDef,
diff --git a/crates/ra_hir/src/ty/infer/unify.rs b/crates/ra_hir/src/ty/infer/unify.rs
index e7e8825d1..9a0d2d8f9 100644
--- a/crates/ra_hir/src/ty/infer/unify.rs
+++ b/crates/ra_hir/src/ty/infer/unify.rs
@@ -3,7 +3,7 @@
 use super::{InferenceContext, Obligation};
 use crate::db::HirDatabase;
 use crate::ty::{
-    Canonical, InEnvironment, InferTy, ProjectionPredicate, ProjectionTy, TraitRef, Ty,
+    Canonical, InEnvironment, InferTy, ProjectionPredicate, ProjectionTy, TraitRef, Ty, TypeWalk,
 };
 
 impl<'a, D: HirDatabase> InferenceContext<'a, D> {
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index 0011c06b4..f6f0137cf 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -10,6 +10,7 @@ use std::sync::Arc;
 
 use super::{
     FnSig, GenericPredicate, ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
+    TypeWalk,
 };
 use crate::{
     adt::VariantDef,
diff --git a/crates/ra_hir/src/ty/traits.rs b/crates/ra_hir/src/ty/traits.rs
index 25316bc02..6e0271a96 100644
--- a/crates/ra_hir/src/ty/traits.rs
+++ b/crates/ra_hir/src/ty/traits.rs
@@ -8,7 +8,7 @@ use ra_db::salsa;
 use ra_prof::profile;
 use rustc_hash::FxHashSet;
 
-use super::{Canonical, GenericPredicate, HirDisplay, ProjectionTy, TraitRef, Ty};
+use super::{Canonical, GenericPredicate, HirDisplay, ProjectionTy, TraitRef, Ty, TypeWalk};
 use crate::{db::HirDatabase, Crate, ImplBlock, Trait};
 
 use self::chalk::{from_chalk, ToChalk};
@@ -138,25 +138,13 @@ pub struct ProjectionPredicate {
     pub ty: Ty,
 }
 
-impl ProjectionPredicate {
-    pub fn subst(mut self, substs: &super::Substs) -> ProjectionPredicate {
-        self.walk_mut(&mut |ty| match ty {
-            Ty::Param { idx, .. } => {
-                if let Some(t) = substs.get(*idx as usize).cloned() {
-                    *ty = t;
-                }
-            }
-            _ => {}
-        });
-        self
-    }
-
-    pub fn walk(&self, f: &mut impl FnMut(&Ty)) {
+impl TypeWalk for ProjectionPredicate {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
         self.projection_ty.walk(f);
         self.ty.walk(f);
     }
 
-    pub fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
+    fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
         self.projection_ty.walk_mut(f);
         self.ty.walk_mut(f);
     }
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 3ab5b7cca..c201c5e50 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -19,6 +19,7 @@ use crate::{
     ty::display::HirDisplay,
     ty::{
         ApplicationTy, CallableDef, GenericPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
+        TypeWalk,
     },
     Crate, HasGenericParams, ImplBlock, ImplItem, Trait, TypeAlias,
 };