2 files changed, 28 insertions, 12 deletions

diff --git a/crates/ra_syntax/src/ast/edit.rs b/crates/ra_syntax/src/ast/edit.rs
index 2ef173a03..abc7a646c 100644
--- a/crates/ra_syntax/src/ast/edit.rs
+++ b/crates/ra_syntax/src/ast/edit.rs
@@ -189,6 +189,21 @@ impl ast::RecordFieldList {
     }
 }
 
+impl ast::TypeAliasDef {
+    #[must_use]
+    pub fn remove_bounds(&self) -> ast::TypeAliasDef {
+        let colon = match self.colon_token() {
+            Some(it) => it,
+            None => return self.clone(),
+        };
+        let end = match self.type_bound_list() {
+            Some(it) => it.syntax().clone().into(),
+            None => colon.clone().into(),
+        };
+        self.replace_children(colon.into()..=end, iter::empty())
+    }
+}
+
 impl ast::TypeParam {
     #[must_use]
     pub fn remove_bounds(&self) -> ast::TypeParam {
@@ -299,12 +314,8 @@ impl ast::UseTree {
             Some(it) => it,
             None => return self.clone(),
         };
-        let use_tree = make::use_tree(
-            suffix.clone(),
-            self.use_tree_list(),
-            self.alias(),
-            self.star_token().is_some(),
-        );
+        let use_tree =
+            make::use_tree(suffix, self.use_tree_list(), self.alias(), self.star_token().is_some());
         let nested = make::use_tree_list(iter::once(use_tree));
         return make::use_tree(prefix.clone(), Some(nested), None, false);
 
diff --git a/crates/ra_syntax/src/ast/tokens.rs b/crates/ra_syntax/src/ast/tokens.rs
index 2e72d4927..045f69133 100644
--- a/crates/ra_syntax/src/ast/tokens.rs
+++ b/crates/ra_syntax/src/ast/tokens.rs
@@ -1,6 +1,9 @@
 //! There are many AstNodes, but only a few tokens, so we hand-write them here.
 
-use std::convert::{TryFrom, TryInto};
+use std::{
+    borrow::Cow,
+    convert::{TryFrom, TryInto},
+};
 
 use crate::{
     ast::{AstToken, Comment, RawString, String, Whitespace},
@@ -138,11 +141,11 @@ impl HasQuotes for String {}
 impl HasQuotes for RawString {}
 
 pub trait HasStringValue: HasQuotes {
-    fn value(&self) -> Option<std::string::String>;
+    fn value(&self) -> Option<Cow<'_, str>>;
 }
 
 impl HasStringValue for String {
-    fn value(&self) -> Option<std::string::String> {
+    fn value(&self) -> Option<Cow<'_, str>> {
         let text = self.text().as_str();
         let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
 
@@ -156,15 +159,17 @@ impl HasStringValue for String {
         if has_error {
             return None;
         }
-        Some(buf)
+        // FIXME: don't actually allocate for borrowed case
+        let res = if buf == text { Cow::Borrowed(text) } else { Cow::Owned(buf) };
+        Some(res)
     }
 }
 
 impl HasStringValue for RawString {
-    fn value(&self) -> Option<std::string::String> {
+    fn value(&self) -> Option<Cow<'_, str>> {
         let text = self.text().as_str();
         let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
-        Some(text.to_string())
+        Some(Cow::Borrowed(text))
     }
 }