[FIXED] What does the Some(..) syntax mean?

Issue

I wrote this snippet:

let my_option: Option<()> = None;
if my_option.is_some() {
    my_option.unwrap();
}

Clippy is telling me to use:

if let Some(..) = my_option {
    my_option.unwrap();
}

What does Some(..) mean? Is it just dropping the value similar to how using _ would in some cases? And where can I find more information about when and where I can use the ..?

Solution

Completing the excellent answer by @SvenMarnach, .. does have a meaning in patterns and it's indeed very similar to _: while _ means "ignore one field here", .. means "ignore zero or more fields here".

As such, in almost any place you can use _ you can also use .., although it can lead to mistakes if fields are added later. The only exceptions are identifier patterns - you can do if let _ = 123 but not if let .. = 123, and struct patterns because it has special syntax: ignoring one field is Struct { field: _ }, while ignoring many is Struct { .. }.

Answered By - Chayim Friedman

Answer Checked By - Willingham (PHPFixing Volunteer)