Add missing tests

Author: rail-rain

tests/ui/manual_memcpy.rs

@@ -99,6 +99,16 @@ pub fn manual_copy(src: &[i32], dst: &mut [i32], dst2: &mut [i32]) {
         dst[i] = src[i - from];
     }
 
+    #[allow(clippy::identity_op)]
+    for i in 0..5 {
+        dst[i - 0] = src[i];
+    }
+
+    #[allow(clippy::reverse_range_loop)]
+    for i in 0..0 {
+        dst[i] = src[i];
+    }
+
     // `RangeTo` `for` loop - don't trigger lint
     for i in 0.. {
         dst[i] = src[i];

tests/ui/manual_memcpy.stderr

@@ -67,10 +67,22 @@ LL |     for i in from..from + 3 {
    |              ^^^^^^^^^^^^^^ help: try replacing the loop by: `dst[from..from + 3].clone_from_slice(&src[..(from + 3 - from)])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:110:14
+  --> $DIR/manual_memcpy.rs:103:14
+   |
+LL |     for i in 0..5 {
+   |              ^^^^ help: try replacing the loop by: `dst[..5].clone_from_slice(&src[..5])`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/manual_memcpy.rs:108:14
+   |
+LL |     for i in 0..0 {
+   |              ^^^^ help: try replacing the loop by: `dst[..0].clone_from_slice(&src[..0])`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/manual_memcpy.rs:120:14
    |
 LL |     for i in 0..src.len() {
    |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[..])`
 
-error: aborting due to 11 previous errors
+error: aborting due to 13 previous errors