rollup merge of #23601: nikomatsakis/by-value-index

This is a [breaking-change]. When indexing a generic map (hashmap, etc) using the `[]` operator, it is now necessary to borrow explicitly, so change `map[key]` to `map[&key]` (consistent with the `get` routine). However, indexing of string-valued maps with constant strings can now be written `map["abc"]`.

r? @japaric
cc @aturon @Gankro

1 files changed, 12 insertions, 0 deletions

diff --git a/src/libstd/ffi/os_str.rs b/src/libstd/ffi/os_str.rs
index 4d411046632..5851c6e2998 100644
--- a/src/libstd/ffi/os_str.rs
+++ b/src/libstd/ffi/os_str.rs
@@ -133,6 +133,7 @@ impl<'a> From<&'a OsStr> for OsString {
     }
 }
 
+#[cfg(stage0)]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Index<ops::RangeFull> for OsString {
     type Output = OsStr;
@@ -143,6 +144,17 @@ impl ops::Index<ops::RangeFull> for OsString {
     }
 }
 
+#[cfg(not(stage0))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl ops::Index<ops::RangeFull> for OsString {
+    type Output = OsStr;
+
+    #[inline]
+    fn index(&self, _index: ops::RangeFull) -> &OsStr {
+        unsafe { mem::transmute(self.inner.as_slice()) }
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Deref for OsString {
     type Target = OsStr;