Test case for #7175

Author: odersky

tests/pos/i7175.scala

@@ -0,0 +1,59 @@
+object foo {
+  def main(args: Array[String]): Unit = println("Dotty")
+
+  import java.net.URL
+  import java.util.List
+
+  trait ConfigOrigin {
+    def description: String
+    def filename: String
+    def url: URL
+    def resource: String
+    def lineNumber: Int
+    def comments: List[String]
+    def withComments(comments: List[String]): ConfigOrigin
+    def withLineNumber(lineNumber: Int): ConfigOrigin
+  }
+
+
+  trait ConfigValue extends ConfigMergeable {
+    def origin: ConfigOrigin
+    //def valueType: ConfigValueType
+    def unwrapped: AnyRef
+    def render: String
+    //def render(options: ConfigRenderOptions): String
+    override def withFallback(other: ConfigMergeable): ConfigValue
+    //def atPath(path: String): Config
+    //def atKey(key: String): Config
+    def withOrigin(origin: ConfigOrigin): ConfigValue
+  }
+
+
+  trait ConfigMergeable {
+    def withFallback(other: ConfigMergeable): ConfigMergeable
+  }
+
+  trait MergeableValue extends ConfigMergeable {
+    def toFallbackValue(): ConfigValue
+  }
+
+  // no impl
+  final class SimpleConfigOrigin extends ConfigOrigin {
+    def comments: java.util.List[String] = ???
+    def description: String = ???
+    def filename: String = ???
+    def lineNumber: Int = ???
+    def resource: String = ???
+    def url: java.net.URL = ???
+    def withComments(comments: java.util.List[String]): foo.ConfigOrigin = ???
+    def withLineNumber(lineNumber: Int): foo.ConfigOrigin = ???
+  }
+
+  abstract class AbstractConfigValue (val _origin: ConfigOrigin)
+    extends ConfigValue
+    with MergeableValue {
+
+  override def origin: SimpleConfigOrigin =
+    this._origin.asInstanceOf[SimpleConfigOrigin]
+  }
+}