4 files changed, 22 insertions, 15 deletions

diff --git a/crates/ra_hir_def/src/data.rs b/crates/ra_hir_def/src/data.rs
index 5ca331380..f9e5701db 100644
--- a/crates/ra_hir_def/src/data.rs
+++ b/crates/ra_hir_def/src/data.rs
@@ -38,7 +38,7 @@ impl FunctionData {
 
         Arc::new(FunctionData {
             name: func.name.clone(),
-            params: func.params.clone(),
+            params: func.params.to_vec(),
             ret_type: func.ret_type.clone(),
             attrs: item_tree.attrs(loc.id.value.into()).clone(),
             has_self_param: func.has_self_param,
@@ -70,7 +70,7 @@ impl TypeAliasData {
             name: typ.name.clone(),
             type_ref: typ.type_ref.clone(),
             visibility: item_tree[typ.visibility].clone(),
-            bounds: typ.bounds.clone(),
+            bounds: typ.bounds.to_vec(),
         })
     }
 }
diff --git a/crates/ra_hir_def/src/item_tree.rs b/crates/ra_hir_def/src/item_tree.rs
index 9e1fd904f..5155b6111 100644
--- a/crates/ra_hir_def/src/item_tree.rs
+++ b/crates/ra_hir_def/src/item_tree.rs
@@ -438,7 +438,7 @@ pub struct Function {
     pub generic_params: GenericParamsId,
     pub has_self_param: bool,
     pub is_unsafe: bool,
-    pub params: Vec<TypeRef>,
+    pub params: Box<[TypeRef]>,
     pub ret_type: TypeRef,
     pub ast_id: FileAstId<ast::FnDef>,
 }
@@ -505,7 +505,7 @@ pub struct Trait {
     pub visibility: RawVisibilityId,
     pub generic_params: GenericParamsId,
     pub auto: bool,
-    pub items: Vec<AssocItem>,
+    pub items: Box<[AssocItem]>,
     pub ast_id: FileAstId<ast::TraitDef>,
 }
 
@@ -515,7 +515,7 @@ pub struct Impl {
     pub target_trait: Option<TypeRef>,
     pub target_type: TypeRef,
     pub is_negative: bool,
-    pub items: Vec<AssocItem>,
+    pub items: Box<[AssocItem]>,
     pub ast_id: FileAstId<ast::ImplDef>,
 }
 
@@ -524,7 +524,7 @@ pub struct TypeAlias {
     pub name: Name,
     pub visibility: RawVisibilityId,
     /// Bounds on the type alias itself. Only valid in trait declarations, eg. `type Assoc: Copy;`.
-    pub bounds: Vec<TypeBound>,
+    pub bounds: Box<[TypeBound]>,
     pub generic_params: GenericParamsId,
     pub type_ref: Option<TypeRef>,
     pub ast_id: FileAstId<ast::TypeAliasDef>,
@@ -541,7 +541,7 @@ pub struct Mod {
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum ModKind {
     /// `mod m { ... }`
-    Inline { items: Vec<ModItem> },
+    Inline { items: Box<[ModItem]> },
 
     /// `mod m;`
     Outline {},
diff --git a/crates/ra_hir_def/src/item_tree/lower.rs b/crates/ra_hir_def/src/item_tree/lower.rs
index b1847a6cb..6e31266a2 100644
--- a/crates/ra_hir_def/src/item_tree/lower.rs
+++ b/crates/ra_hir_def/src/item_tree/lower.rs
@@ -325,7 +325,7 @@ impl Ctx {
             generic_params: GenericParamsId::EMPTY,
             has_self_param,
             is_unsafe: func.unsafe_token().is_some(),
-            params,
+            params: params.into_boxed_slice(),
             ret_type,
             ast_id,
         };
@@ -344,7 +344,14 @@ impl Ctx {
         let bounds = self.lower_type_bounds(type_alias);
         let generic_params = self.lower_generic_params(GenericsOwner::TypeAlias, type_alias);
         let ast_id = self.source_ast_id_map.ast_id(type_alias);
-        let res = TypeAlias { name, visibility, bounds, generic_params, type_ref, ast_id };
+        let res = TypeAlias {
+            name,
+            visibility,
+            bounds: bounds.into_boxed_slice(),
+            generic_params,
+            type_ref,
+            ast_id,
+        };
         Some(id(self.data().type_aliases.alloc(res)))
     }
 
@@ -384,7 +391,7 @@ impl Ctx {
                     })
                     .unwrap_or_else(|| {
                         mark::hit!(name_res_works_for_broken_modules);
-                        Vec::new()
+                        Box::new([]) as Box<[_]>
                     }),
             }
         };
@@ -552,7 +559,7 @@ impl Ctx {
             GenericsOwner::Function(func) => {
                 generics.fill(&self.body_ctx, sm, node);
                 // lower `impl Trait` in arguments
-                for param in &func.params {
+                for param in &*func.params {
                     generics.fill_implicit_impl_trait_args(param);
                 }
             }
diff --git a/crates/ra_hir_def/src/item_tree/tests.rs b/crates/ra_hir_def/src/item_tree/tests.rs
index b72f0f47b..cd4c8a199 100644
--- a/crates/ra_hir_def/src/item_tree/tests.rs
+++ b/crates/ra_hir_def/src/item_tree/tests.rs
@@ -31,7 +31,7 @@ fn test_inner_items(ra_fixture: &str) {
             ModItem::TypeAlias(it) => tree.source(&db, InFile::new(file_id, it)).into(),
             ModItem::Mod(it) => {
                 if let ModKind::Inline { items } = &tree[it].kind {
-                    worklist.extend(items);
+                    worklist.extend(&**items);
                 }
                 tree.source(&db, InFile::new(file_id, it)).into()
             }
@@ -125,14 +125,14 @@ fn fmt_mod_item(out: &mut String, tree: &ItemTree, item: ModItem) {
         }
         ModItem::Trait(it) => {
             format_to!(out, "{:?}", tree[it]);
-            for item in &tree[it].items {
+            for item in &*tree[it].items {
                 fmt_mod_item(&mut children, tree, ModItem::from(*item));
                 format_to!(children, "\n");
             }
         }
         ModItem::Impl(it) => {
             format_to!(out, "{:?}", tree[it]);
-            for item in &tree[it].items {
+            for item in &*tree[it].items {
                 fmt_mod_item(&mut children, tree, ModItem::from(*item));
                 format_to!(children, "\n");
             }
@@ -144,7 +144,7 @@ fn fmt_mod_item(out: &mut String, tree: &ItemTree, item: ModItem) {
             format_to!(out, "{:?}", tree[it]);
             match &tree[it].kind {
                 ModKind::Inline { items } => {
-                    for item in items {
+                    for item in &**items {
                         fmt_mod_item(&mut children, tree, *item);
                         format_to!(children, "\n");
                     }