New lint: needless `Path::new`

[ada4a]

What it does

Checks whether a &str is wrapped in Path::new before being passed to a function that accepts impl AsRef<Path>. So somewhat similar to needless_borrow

Advantage

• more concise
• avoids the import

Drawbacks

can't think of any...

Example

std::fs::write(Path::new("foo.txt"), "foo");

Could be written as:

std::fs::write("foo.txt", "foo");

[ada4a]

I've never implemented a lint before, but would like to try implementing this one if it's deemed useful:)

[ada4a]

The same goes for wrapping in &PathBuf::from, which is even since it makes a completely needless allocation

[ada4a]

Reading through the guide, it looks like this lint will need to be late-pass, and so somewhat more complicated. The guide mentions LatePassLint, but it's hard to understand what its methods are supposed to do since there doesn't seem to be any documentation whatsoever. I would appreciate pointers to similar lints so that I could hopefully imitate them...

[Alexendoo]

A lint pass visits the whole crate, whenever the visitor sees an expression for example it calls check_expr, when it sees an item it will call check_item etc.

The individual docs for Item, Expr and so on have more details