Result.map Example Err(..) meaning?

1

Reading the Example for Result.map i stumbled upon the Err Variant

let line = "1\n2\n3\n4\n";

for num in line.lines() {
    match num.parse::<i32>().map(|i| i * 2) {
        Ok(n) => println!("{n}"),
        Err(..) => {}
    }
}

What does Err(..) mean here?
.. = RangeFull?

2

When you parse the str, you create a Result<i32, std::num::ParseIntError>. The Result::map method changes the Ok value if it is Ok, and leaves Err untouched if not. At this point, it is still a Result. You match the Result, and the .. just means "match all values. (In every field of the n-ary tuple.)" It is similar to _.

3

.. in a few contexts means all remaining fields / all remaining members of a tuple / all remaining elements of a slice or array.

in this case Result(..) means a result variant with all of it's content ignored

4

the .. token here is the "rest pattern", not the range operator.

5

I am a little curious why they used it in that example. There's still only one value in the Err variant, even if that value is a struct in this case. Is this a common idiom, for people to default to .. instead of _ since it's more general? (not that this matters much anyways)