kotlin-fork/compiler/testData/diagnostics/tests/when/withSubjectVariable/reassignmentToWhenSubjectVariable.kt

// !LANGUAGE: +VariableDeclarationInWhenSubject
// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -UNUSED_VALUE

fun foo(): Any = 42

fun test1(x: Any) {
    when (val y = foo()) {
        is String -> <!VAL_REASSIGNMENT!>y<!> = ""
    }
}