New lint for zip with array length instead of enumerate()

[nweston]

Fixes #11.

I have one question about this: I'm matching an expression like x.iter().zip(0..x.len()) and I need to check that .iter() and .len() are called on the same thing. Right now I compare the snippet() of the two expressions but that seems kludgey. Is there a better way to check that two expressions are equivalent?

[Manishearth]

"x" will be an ExprPath with a single element.

[nweston]

In this example, sure. But in practice it could be something more complicated (a method call that returns a vector, for example). Unless we want the lint to ignore anything that isn't an ExprPath.

[Manishearth]

The method call could return a different vector each time. So yeah, simple variable access only 😄

[llogiq]

Yeah, perhaps we could allow simple blocks, like {x}, but I wouldn't do anything more complex.

[nweston]

OK, I changed it to expect ExprPath in both places and compare those.

[llogiq]

Thanks for the PR! I just added a wiki entry, too.