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LeakingImplicitClassVal

Non-private val fields of implicit classes leak as publicly accessible extension methods. This rule adds the private access modifier on the field of implicit value classes in order to prevent direct access.

// before implicit class XtensionVal(val str: String) extends AnyVal { def doubled: String = str + str } "message".str // compiles // after implicit class XtensionValFixed(private val str: String) extends AnyVal { def doubled: String = str + str } "message".str // does not compile 

This rule only triggers for val fields, it ignores other modifiers such as var.