Trailing commas in enums

[Kantis]

Description

I noticed trailing commas in enums seems to be unhandled by the trialing-comma rule. Added tests to verify that it is unhandled at the moment. I would be up for trying to add handling for enums as well, if you agree that it should be handled.

Checklist

• PR description added
• tests are added
• CHANGELOG.md is updated

[paul-dingemans]

It is okay to add a trailing comma in enumerations although this is not yet handled correctly by IntelliJ IDEA default formatter (for example see https://youtrack.jetbrains.com/issue/KTIJ-19916/Enabledisable-trailing-comma-in-the-formatter-intention-is-not-provided-when-trailing-comma-is-used-in-enumerations). The reason that it is okay to add in Ktlint is that IntelliJ does accept enums with or without trailing comma's regardless of the settings. So implementing it correctly in Ktlint will not lead to a conflict with de default IntelliJ IDEA formatter.

[paul-dingemans]

Please mind handling of enum which also contain addition declarations.

Add/remove trailing commain case below depending on setting:

enum class SomeEnum1(id: String) {
    FOO("foo"),
    BAR("bar"),
    ;
    
    fun doSomething(id: String) {}
}

Note that the ; might need to be wrapped to a separate line in case the BAR item in the original code was followed by ; on the same line.

enum class SomeEnum1(id: String) {
    FOO("foo"),
    BAR("bar"), // some EOL comment
    ;
    
    fun doSomething(id: String) {}
}

enum class SomeEnum1(id: String) {
    FOO("foo"),
    BAR("bar") /* some block comment */,
    ;
    
    fun doSomething(id: String) {}
}

Finnally do not add a trailing comma in case the one-but-last and the last enumeration value are on the same line.

[paul-dingemans]

Thanks for your contribution. Please address the issues.

[paul-dingemans]

Hi @Kantis,

Are you making any progress on this issue and are you able to finish in a couple of days? This PR is blocking #1555 (ready to be merged to master) and as a consequence also #1557.

[Kantis]

Hi @Kantis,

Are you making any progress on this issue and are you able to finish in a couple of days? This PR is blocking #1555 (ready to be merged to master) and as a consequence also #1557.

Sorry for blocking. I've been zoned out a bit from coding, but I'll put in some effort to get this done to unblock the other things.

[paul-dingemans]

Code is looking good. I have simplied the code a bit and made it more consistent with other parts of the code base.