Merge pull request #354 from Pyriphlegethon/master

Add "unnecessary mut passed" lint

tests/compile-fail/for_loop.rs

@@ -16,7 +16,7 @@ impl Unrelated {
 
 #[deny(needless_range_loop, explicit_iter_loop, iter_next_loop, reverse_range_loop, explicit_counter_loop)]
 #[deny(unused_collect)]
-#[allow(linkedlist,shadow_unrelated)]
+#[allow(linkedlist,shadow_unrelated,unnecessary_mut_passed)]
 fn main() {
     let mut vec = vec![1, 2, 3, 4];
     let vec2 = vec![1, 2, 3, 4];

tests/compile-fail/mut_reference.rs

@@ -0,0 +1,46 @@
+#![feature(plugin)]
+#![plugin(clippy)]
+
+#![allow(unused_variables)]
+
+fn takes_an_immutable_reference(a: &i32) {
+}
+
+
+fn takes_a_mutable_reference(a: &mut i32) {
+}
+
+struct MyStruct;
+
+impl MyStruct {
+    fn takes_an_immutable_reference(&self, a: &i32) {
+    }
+
+    fn takes_a_mutable_reference(&self, a: &mut i32) {
+    }
+}
+
+#[deny(unnecessary_mut_passed)]
+fn main() {
+    // Functions
+    takes_an_immutable_reference(&mut 42); //~ERROR The function/method "takes_an_immutable_reference" doesn't need a mutable reference
+    
+    // Methods
+    let my_struct = MyStruct;
+    my_struct.takes_an_immutable_reference(&mut 42); //~ERROR The function/method "takes_an_immutable_reference" doesn't need a mutable reference
+    
+
+    // No error
+    
+    // Functions
+    takes_an_immutable_reference(&42);
+    takes_a_mutable_reference(&mut 42);
+    let a = &mut 42;
+    takes_an_immutable_reference(a);
+    
+    // Methods
+    my_struct.takes_an_immutable_reference(&42);
+    my_struct.takes_a_mutable_reference(&mut 42);
+    my_struct.takes_an_immutable_reference(a);
+    
+}