Report lines starting with &&.

python/tidy/servo_tidy/tidy.py

@@ -378,6 +378,7 @@ def check_rust(file_name, lines):
             (r": &Vec<", "use &[T] instead of &Vec<T>", no_filter),
             # No benefit over using &str
             (r": &String", "use &str instead of &String", no_filter),
+            (r"^&&", "operators should go at the end of the first line", no_filter),
         ]
 
         for pattern, message, filter_func in regex_rules:

python/tidy/servo_tidy_tests/rust_tidy.rs

@@ -32,6 +32,9 @@ impl test {
     }
 
     fn test_fun2(y : &String, z : &Vec<f32>) -> f32 {
-        1
+        let x = true;
+        x
+            && x;
     }
+
 }

python/tidy/servo_tidy_tests/test_tidy.py

@@ -70,6 +70,7 @@ class CheckTidiness(unittest.TestCase):
         self.assertEqual('extra space before :', errors.next()[2])
         self.assertEqual('use &[T] instead of &Vec<T>', errors.next()[2])
         self.assertEqual('use &str instead of &String', errors.next()[2])
+        self.assertEqual('operators should go at the end of the first line', errors.next()[2])
         self.assertNoMoreErrors(errors)
 
     def test_spec_link(self):