perf: use `next_back` on `DoubleEndedIterator`

helix-core/src/test.rs

@@ -65,7 +65,7 @@ pub fn print(s: &str) -> (String, Selection) {
         let head_at_beg = iter.next_if_eq(&"|").is_some();
         let last_grapheme = |s: &str| {
             UnicodeSegmentation::graphemes(s, true)
-                .last()
+                .next_back()
                 .map(String::from)
         };
 

helix-lsp/src/client.rs

@@ -39,7 +39,7 @@ fn workspace_for_uri(uri: lsp::Url) -> WorkspaceFolder {
     lsp::WorkspaceFolder {
         name: uri
             .path_segments()
-            .and_then(|segments| segments.last())
+            .and_then(|mut segments| segments.next_back())
             .map(|basename| basename.to_string())
             .unwrap_or_default(),
         uri,

helix-view/src/register.rs

@@ -145,7 +145,8 @@ impl Registers {
     }
 
     pub fn last<'a>(&'a self, name: char, editor: &'a Editor) -> Option<Cow<'a, str>> {
-        self.read(name, editor).and_then(|values| values.last())
+        self.read(name, editor)
+            .and_then(|mut values| values.next_back())
     }
 
     pub fn iter_preview(&self) -> impl Iterator<Item = (char, &str)> {