Allow BCode to emit default interface methods

A DefDef owned by a trait may now have have a method body.
Such a method must be emitted without ACC_ABSTRACT, and
with the code attribute.

Tested by intercepting the compile pipeline and adding the
DEFAULTMETHOD flag and a method body before running
the backend.

1 files changed, 43 insertions, 0 deletions

diff --git a/test/junit/scala/tools/nsc/backend/jvm/DefaultMethodTest.scala b/test/junit/scala/tools/nsc/backend/jvm/DefaultMethodTest.scala
new file mode 100644
index 0000000000..f9a55bb26e
--- /dev/null
+++ b/test/junit/scala/tools/nsc/backend/jvm/DefaultMethodTest.scala
@@ -0,0 +1,43 @@
+package scala.tools.nsc.backend.jvm
+
+import org.junit.Assert._
+import org.junit.Test
+
+import scala.collection.JavaConverters
+import scala.tools.asm.Opcodes
+import scala.tools.asm.tree.ClassNode
+import scala.tools.nsc.backend.jvm.CodeGenTools._
+import JavaConverters._
+import scala.tools.testing.ClearAfterClass
+
+object DefaultMethodTest extends ClearAfterClass.Clearable {
+  var compiler = newCompiler(extraArgs = "-Ybackend:GenBCode")
+  def clear(): Unit = { compiler = null }
+}
+
+class DefaultMethodTest extends ClearAfterClass {
+  ClearAfterClass.stateToClear = DirectCompileTest
+  val compiler = DirectCompileTest.compiler
+
+  @Test
+  def defaultMethodsViaGenBCode(): Unit = {
+    import compiler._
+    val code = "package pack { trait T { def foo: Int }}"
+    object makeFooDefaultMethod extends Transformer {
+      val Foo = TermName("foo")
+      /** Transforms a single tree. */
+      override def transform(tree: compiler.Tree): compiler.Tree = tree match {
+        case dd @ DefDef(_, Foo, _, _, _, _) =>
+          dd.symbol.setFlag(reflect.internal.Flags.JAVA_DEFAULTMETHOD)
+          copyDefDef(dd)(rhs = Literal(Constant(1)).setType(definitions.IntTpe))
+        case _ => super.transform(tree)
+      }
+    }
+    val asmClasses: List[ClassNode] = readAsmClasses(compileTransformed(compiler)(code, Nil, makeFooDefaultMethod.transform(_)))
+    val foo = asmClasses.head.methods.iterator.asScala.toList.last
+    assertTrue("default method should not be abstract", (foo.access & Opcodes.ACC_ABSTRACT) == 0)
+    assertTrue("default method body emitted", foo.instructions.size() > 0)
+  }
+
+
+}