Formatting of list-patterns on multiple lines is incorrect

[jcouv]

This issue is referenced in tests from PR #53850

Relates to test plan #51289

[jcouv]

@jinujoseph I'm afraid this issue needs attention from someone with a bit more expertise. I tried to fix this today but was unable to.

[sharwell]

@jcouv I looked at the linked PR and wasn't able to figure out what the request here is.

[jcouv]

@sharwell My PR fixed formatting of list-patterns on a single line (which is the common case). But when it comes to multi-line format, it's probably not right (it's not doing anything).
Specifically:

1. if you type x is [ <enter>, we probably want the open brace to be pushed to the next line and the cursor to be place with a deeper indentation like this:

_ = x is
[
    $$
]

2. if you start from a non-formatted multi-line sample like the following, we don't know how to properly format it:

    _ = x is
        [
1,
    2,
 ];

It probably should be something like one of these two (not sure which):

    _ = x is
    [
        1,
        2,
    ];

or maybe

    _ = x is
        [
            1,
            2,
        ];

Note: the existing scenario with braces is array instantiation. We also don't know how to format those on multiple lines (I guess it's very uncommon as well).

[davidwengier]

@jinujoseph I'm afraid this issue needs attention from someone with a bit more expertise. I tried to fix this today but was unable to.

Good news, its been assigned to me.

Bad news, I've literally never touched or seen the C# formatter code 😛

[jcouv]

Thanks @davidwengier
If that helps, I've been collecting notes from my previous forays. We can build on that and make it easier for next time.
https://github.com/dotnet/roslyn/blob/main/docs/wiki/Notes-on-formatting.md

[jcouv]

Thanks @davidwengier for fixing this!