Remove unnecessary casts in SyntaxRewriter

[natikgadzhi]

This pull request removes unnecessary casts in SyntaxRewriter, i.e. funcs that look like this:

open func visit(_ node: AttributeListSyntax) -> AttributeListSyntax {
    return Syntax(visitChildren(node)).cast(AttributeListSyntax.self)
}

become this:

open func visit(_ node: AttributeListSyntax) -> AttributeListSyntax {
    return visitChildren(node)
}

It's more readable, and visitChildren(node) is guaranteed to return the same type as node anyway, so the cast is unnecessary. Thank you, @Matejkob, for filing the issue with pointers on how to get started!

Closes #2102.

Disclaimer: I'm here to learn, and just making my first steps. Please feel free to "well, actually" me.

TODOs

• Tests crash locally without SKIP_LONG_TESTS. The crash is in SyntaxVisitor.visit and pretty deep. But, they also crash for me on main. 👀

[natikgadzhi]

Oh, a lot of these is just swift-format 508.0.1.

[Matejkob]

https://github.com/apple/swift-syntax/blob/b4749403093de49b11418d7bd80f7ee2b4a926dd/CONTRIBUTING.md?plain=1#L26

swift-format doesn't format generated code, so I think something went awry during the code generation process. Would you mind re-running the code generation to try to fix it?

[Matejkob]

Thank you, @natikgadzhi, for working on this! ❤️

[natikgadzhi]

I ran swift-format format Sources/SwiftSyntax/generated/SyntaxRewriter.swift —in-place manually. Happy to generate without formatting through — my bad, I should have just ran format.py

[natikgadzhi]

There! Much cleaner now.

[ahoppen]

Nice. Thank you. So much cleaner. 🤩

[ahoppen]

Happy to generate without formatting through — my bad, I should have just ran format.py

We don’t manually format the generated files because the formatting will disappear the next time that you re-run CodeGeneration, which makes it hard to spot the modifications made by CodeGeneration.

[ahoppen]

@swift-ci Please test

[kimdv]

Thanks @natikgadzhi 🙌

[ahoppen]

@swift-ci Please test