Formatter: Match (includes MatchCase and Patterns)

[konstin]

This is a bigger project that includes the following nodes:

• Formatter: StmtMatch #6298
• Formatter: MatchCase #6299
• Format PatternMatchAs #6641
• Format PatternMatchClass #6642
• Format PatternMatchMapping #6644
• Format PatternMatchOr #6643
• Format PatternMatchSequence #6645
• Format PatternMatchSingleton #6557
• Format PatternMatchStar #6558
• Format PatternMatchValue #6555
• Preserve pattern parentheses #6753
• Can omit parentheses layout for patterns #6933

The match arms have the same considerations for comments as if branches or try-except branches.

[MichaReiser]

As a note. The idea isn't that this is all implemented in a single PR. I recommend to start implementing StmtMatch and stubbing out the match cases (if they aren't already). We can then add support for the match statements one by one

[dhruvmanila]

Regarding the match patterns, I would say that PatternMatchValue, PatternMatchSingleton, PatternMatchStar, PatternMatchSequence (sequence of other patterns), and PatternMatchOr (similar to PatternMatchSequence) are good first issues and could be taken on in the order mentioned.

[evanrittenhouse]

I can take those pattern issues! Feel free to assign them to me

[MichaReiser]

I can take those pattern issues! Feel free to assign them to me

Awesome. Let's start with one to leave an opportunity for other contributors too. Can you pick one and comment on the issue so that I can assign it to you?

[MichaReiser]

I don't think this is ready yet. We first need to land #6594 (@evanrittenhouse you can work on top of that PR, as long as you don't mind that there's one failing test).

[cnpryer]

Is #6933 still required for the Alpha release? Looks like it’s marked as Beta.

[charliermarsh]

My impression is that #6933 shouldn't be blocking for alpha.