Structs with duplicate methods do not cause compilation warning or error

```
pub struct Foo;

impl Foo {
    pub fn bar(&self) {
        println("I'm bar 1");
    }

    pub fn bar(&self) {
        println("I'm bar 2");
    }
}

fn main() {
    let foo = Foo;
    foo.bar();
}
```

The above program compiles and prints `I'm bar 1`.
