Naming rules should allow keywords to be wrapped between backticks

[dimasadryantos]

Expected Behavior

Function name with backticks and short name should not throwing an error when formatting.

Observed Behavior

Ktlint detect function name with backticks wrongly for example if I have method like in the following :

fun `when`(): String {
    return ""
}

when I format the code it would throw an error like the following :
[ktlint] /Users/dsetyawan/Documents/pAPI/spring-kotlin-demo/src/main/kotlin/com/example/springkotlindemo/SpringKotlinDemoApplication.kt:13:5: Function name should start with a lowercase letter (except factory methods) and use camel case (standard:function-naming)

Steps to Reproduce

Clone my example project : https://github.com/dimasadryantos/spring-kotlin-demo/tree/master
Run : mvn clean compile or ktlint --format

Your Environment

• Version of ktlint used: 0.51.0-FINAL
• Operating System and version: Mac
• Detailed in dependencies provided in pom.xml https://github.com/dimasadryantos/spring-kotlin-demo/blob/master/pom.xml

[paul-dingemans]

Duplicate of #2339

[JakeWharton]

This is not a duplicate of that issue. You cannot remove the backticks here as the name is otherwise a keyword. Backticks are required to use spaces but it is certainly not their only use.

[paul-dingemans]

This is not a duplicate of that issue. You cannot remove the backticks here as the name is otherwise a keyword. Backticks are required to use spaces but it is certainly not their only use.

Indeed, you can not remove the backticks here.

According to Kotlin coding conventions:

In tests (and only in tests), you can use method names with spaces enclosed in backticks.

So when you read above literally, it would allow the example code above as a kind of helper method inside a Test class. But, from the Kotlin coding conventions it is quite clear that it is meant for functions annotated with @Test.

[JakeWharton]

Right. So this issue should be reopened as there are valid, non-test-based uses of backticks. If you are overriding a Java method whose name is a Kotlin keyword, or you need to provide binary compatibility with a previous version of a library which used a Kotlin keyword as a function or property name they are necessary and should not be flagged.

[dimasadryantos]

I'd agree with @JakeWharton , also this issue is only appear on this version.

[JakeWharton]

In my specific case, I have a property named "package":

val `package` = type.names[0]

It represents a package, so that's what I named it.

The failing rule says

Property name should start with a lowercase letter and use camel case

It does start with a lowercase "p" and use camel case. The backticks are not part of the name. The backticks allow me to tell the compiler's parser that I am producing a variable name and not a hard keyword.

[paul-dingemans]

From the view point of the Kotlin parser, the backticks are an integral part of the identifier as can be seen in screenshot below. On the right hand side you the the PSI (AST) structure of the parsed file. The highlighted IDENTIFIER field matches with the name of the variable including the backticks.

But I do see the point that you're making that the keywords should be accepted, even in case they are included between backticks. This applies to rules property-naming, function-naming and class-naming.

[JakeWharton]

Thank you!