Document that Index ops can panic on HashMap & BTreeMap.

Fixes #47011.
rust-lang · Jan 29, 2018 · 7b4cbbd · 7b4cbbd
1 parent 21882aa
commit 7b4cbbd
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/src/liballoc/btree/map.rs b/src/liballoc/btree/map.rs
@@ -1748,6 +1748,11 @@ impl<'a, K: Ord, Q: ?Sized, V> Index<&'a Q> for BTreeMap<K, V>
 {
     type Output = V;
 
+    /// Returns a reference to the value corresponding to the supplied key.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the key is not present in the `BTreeMap`.
     #[inline]
     fn index(&self, key: &Q) -> &V {
         self.get(key).expect("no entry found for key")

diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
@@ -1384,9 +1384,14 @@ impl<'a, K, Q: ?Sized, V, S> Index<&'a Q> for HashMap<K, V, S>
 {
     type Output = V;
 
+    /// Returns a reference to the value corresponding to the supplied key.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the key is not present in the `HashMap`.
     #[inline]
-    fn index(&self, index: &Q) -> &V {
-        self.get(index).expect("no entry found for key")
+    fn index(&self, key: &Q) -> &V {
+        self.get(key).expect("no entry found for key")
     }
 }