specialize ToString for str

2 files changed, 10 insertions, 1 deletions

diff --git a/src/libcollections/lib.rs b/src/libcollections/lib.rs
index a6be81c91bb..8e62b389a6e 100644
--- a/src/libcollections/lib.rs
+++ b/src/libcollections/lib.rs
@@ -48,6 +48,7 @@
 #![feature(placement_new_protocol)]
 #![feature(shared)]
 #![feature(slice_patterns)]
+#![feature(specialization)]
 #![feature(staged_api)]
 #![feature(step_by)]
 #![feature(str_char)]
diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index 98225dd3dda..d552c99c21b 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -1770,7 +1770,7 @@ pub trait ToString {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: fmt::Display + ?Sized> ToString for T {
     #[inline]
-    fn to_string(&self) -> String {
+    default fn to_string(&self) -> String {
         use core::fmt::Write;
         let mut buf = String::new();
         let _ = buf.write_fmt(format_args!("{}", self));
@@ -1779,6 +1779,14 @@ impl<T: fmt::Display + ?Sized> ToString for T {
     }
 }
 
+#[stable(feature = "str_to_string_specialization", since = "1.9.0")]
+impl ToString for str {
+    #[inline]
+    fn to_string(&self) -> String {
+        String::from(self)
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl AsRef<str> for String {
     #[inline]