Simplify the buffer push done by scan_break

Author: dtolnay

compiler/rustc_ast_pretty/src/pp.rs

@@ -311,13 +311,12 @@ impl Printer {
             self.left_total = 1;
             self.right_total = 1;
             self.right = self.left;
-            self.buf.truncate(1);
+            self.buf.clear();
         } else {
-            self.right += 1;
-            self.buf.advance_right();
             self.check_stack(0);
+            self.right += 1;
         }
-        self.buf[self.right] = BufEntry { token: Token::Break(b), size: -self.right_total };
+        self.buf.push(BufEntry { token: Token::Break(b), size: -self.right_total });
         self.scan_stack.push_front(self.right);
         self.right_total += b.blank_space;
     }

compiler/rustc_ast_pretty/src/pp/ring.rs

@@ -41,10 +41,6 @@ impl<T> RingBuffer<T> {
     pub fn clear(&mut self) {
         self.data.clear();
     }
-
-    pub fn truncate(&mut self, len: usize) {
-        self.data.truncate(len);
-    }
 }
 
 impl<T> Index<usize> for RingBuffer<T> {