Eliminate a token clone from advance_left

Author: dtolnay

compiler/rustc_ast_pretty/src/pp.rs

@@ -319,7 +319,7 @@ impl Printer {
         let mut left_size = self.buf.first().unwrap().size;
 
         while left_size >= 0 {
-            let left = self.buf.first().unwrap().token.clone();
+            let left = self.buf.pop_first().unwrap().token;
 
             let len = match left {
                 Token::Break(b) => b.blank_space,
@@ -335,7 +335,6 @@ impl Printer {
 
             self.left_total += len;
 
-            self.buf.advance_left();
             if self.buf.is_empty() {
                 break;
             }

compiler/rustc_ast_pretty/src/pp/ring.rs

@@ -32,11 +32,6 @@ impl<T> RingBuffer<T> {
         index
     }
 
-    pub fn advance_left(&mut self) {
-        self.data.pop_front().unwrap();
-        self.offset += 1;
-    }
-
     pub fn clear(&mut self) {
         self.data.clear();
     }
@@ -53,6 +48,12 @@ impl<T> RingBuffer<T> {
         self.data.front_mut()
     }
 
+    pub fn pop_first(&mut self) -> Option<T> {
+        let first = self.data.pop_front()?;
+        self.offset += 1;
+        Some(first)
+    }
+
     pub fn last(&self) -> Option<&T> {
         self.data.back()
     }