Auto merge of #5894 - tmiasko:self-assignment, r=Manishearth

Warn about explicit self-assignment

Warn about assignments where left-hand side place expression is the same
as right-hand side value expression. For example, warn about assignment in:

```rust
pub struct Event {
    id: usize,
    x: i32,
    y: i32,
}

pub fn copy_position(a: &mut Event, b: &Event) {
    a.x = b.x;
    a.y = a.y;
}
```

changelog: New lint `self_assignment`, checks for explicit self-assignments.

0 files changed, 0 insertions, 0 deletions