Prevent multiple statements on the same line

[hiqua]

Duplicates

I could not find a matching issue, but I find it hard to believe that it doesn't exist yet. Apologies if this is indeed a duplicate.

Expected Rule behavior

Do not allow multiple statements on the same line. ktlint does not complain with the following:

class MissingRules {
    fun f() {
        val a = 3; val b = 2
    }
}

Here, a and b should be declared separately.

Additional information

• Current version of ktlint: 0.40.0
• Styleguide section: https://developer.android.com/kotlin/style-guide#one_statement_per_line

One statement per line
Each statement is followed by a line break. Semicolons are not used.

[paul-dingemans]

I am not aware of any language constructs in Kotlin that use ; as separator between elements.

[atulgpt]

Hi, @paul-dingemans Should we disallow the semicolon itself? Even code like the below is possible in Kotlin. Which are not reported by ktlint

public fun f1() {
    val a = 3; val b = 2
}; public fun f2() {
    val a = 3; val b = 2
}

f1(); f2()

public class A {
    
}; public class B {
    
}

public class A; public class B

[paul-dingemans]

Semi colons can not be removed unconditionally. Ktlint already has a NoSemicolonsRule which removes redundant semi colons. That rule contains references to two interesting exceptions in which the semi colon is actually relevant:

• Using ktlint - f remove wrong semi colon #281
• ParseException ("Expecting an expression") on a ControlFlowWithEmptyBody expression #955

I think it would be best that the statement wrapping rule is just wrapping (e.g. inserting a new line after the semi colon) and not removing the semi colon. And the NoSemicolonRule will then take care of removal of semi colons like it currently does. For this it has to be enforce that the NoSemicolon runs after the statement wrapping rule. This can be done by adding a VisitorModifier.RunAfterRule in the NoSemicolonRule (this rule may run regardless whether the statement wrapping rule is loaded/enabled).