Lint manual swaps

tests/compile-fail/swap.rs

@@ -4,6 +4,8 @@
 #![deny(clippy)]
 #![allow(unused_assignments)]
 
+struct Foo(u32);
+
 fn main() {
     let mut a = 42;
     let mut b = 1337;
@@ -12,6 +14,31 @@ fn main() {
     b = a;
     //~^^ ERROR this looks like you are trying to swap `a` and `b`
     //~| HELP try
-    //~| SUGGESTION std::mem::swap(a, b);
+    //~| SUGGESTION std::mem::swap(&mut a, &mut b);
+    //~| NOTE or maybe you should use `std::mem::replace`?
+
+    let t = a;
+    a = b;
+    b = t;
+    //~^^^ ERROR this looks like you are swapping `a` and `b` manually
+    //~| HELP try
+    //~| SUGGESTION std::mem::swap(&mut a, &mut b);
+    //~| NOTE or maybe you should use `std::mem::replace`?
+
+    let mut c = Foo(42);
+
+    c.0 = a;
+    a = c.0;
+    //~^^ ERROR this looks like you are trying to swap `c.0` and `a`
+    //~| HELP try
+    //~| SUGGESTION std::mem::swap(&mut c.0, &mut a);
+    //~| NOTE or maybe you should use `std::mem::replace`?
+
+    let t = c.0;
+    c.0 = a;
+    a = t;
+    //~^^^ ERROR this looks like you are swapping `c.0` and `a` manually
+    //~| HELP try
+    //~| SUGGESTION std::mem::swap(&mut c.0, &mut a);
     //~| NOTE or maybe you should use `std::mem::replace`?
 }