SI-7825 Consider DEFAULTMETHOD when refchecking concreteness

A class should not be required to implement a Java default method.

This commit uses `isDeferredNotDefault` in place of `isDeferred`
when finding unimplemented methods.

The test itself does not depend on Java 8 as we use scalac's
Java source parser to set things up.

1 files changed, 34 insertions, 0 deletions

diff --git a/test/files/run/t7825.scala b/test/files/run/t7825.scala
new file mode 100644
index 0000000000..65ca06fdfc
--- /dev/null
+++ b/test/files/run/t7825.scala
@@ -0,0 +1,34 @@
+import scala.tools.partest._
+
+object Test extends CompilerTest {
+  import global._
+
+  override lazy val units: List[CompilationUnit] = {
+    // We can test this on JDK6.
+    javaCompilationUnits(global)(defaultMethodSource) ++ compilationUnits(global)(scalaExtendsDefault)
+  }
+
+  private def defaultMethodSource = """
+public interface Iterator<E> {
+    boolean hasNext();
+    E next();
+    default void remove() {
+        throw new UnsupportedOperationException("remove");
+    }
+}
+  """
+
+  private def scalaExtendsDefault = """
+object Test {
+  object X extends Iterator[String] {
+    def hasNext = true
+    def next = "!"
+  }
+}
+  """
+
+  // We're only checking we that the Scala compilation unit passes refchecks
+  // No further checks are needed here.
+  def check(source: String, unit: global.CompilationUnit): Unit = {
+  }
+}