Lint for Unnecessary Map

[mmstick]

It woud be nice if clippy could detect situations where map() is being used unnecessarily to pass a contained value wrapped as either a Result or an Option.

Unnecessarry

let mut file = File::open(path)
         .map(|file| file)
         .unwrap_or_else(|why| panic!("couldn't open {}: {}", infilename, why));

Recommended

let mut file = File::open(infilename)
         .unwrap_or_else(|why| panic!("couldn't open {}: {}", infilename, why));

[shepmaster]

wrapped as either a Result or an Option.

Wouldn't this apply for wider uses of map, such as on an iterator?

[mmstick]

Wouldn't this apply for wider uses of map, such as on an iterator?

I suppose it would also apply for using map(|x| x) uselessly on an Iterator too.

[camsteffen]

Resolved by #5694