lines().count() should warn in case of Err

[DorianCoding]

What it does

As stated here, Lines can enter an infinite loop if nothing like map_while is used when used on directory. Therefore something like lines().count() may enter an infinite loop. Therefore, it would be good if a warn can be added to fix like : lines().map_while(Result::ok).count().

Advantage

• It will avoid entering a loop when used on directory in certain platforms.

Drawbacks

• Some users may be interested in getting the count with lines with errors included.

Example

let linecount = BufReader::new(File::open("some-path")?).lines().count();

Could be warned and this used instead :

let linecount = BufReader::new(File::open("some-path")?).lines().map_while(Result::ok).count();

[scottlamb]

+1 to the idea of having a lint on Iterator<Item = Result<_, _>>::count. I'd prefer the suggested alternative be to bubble up the error rather than swallow it.