Emit trait method bodies in statics

And use this as the target of the default methods or
statically resolved super or $init calls.

The call-site change is predicated on `-Yuse-trait-statics`
as a stepping stone for experimentation / bootstrapping.

I have performed this transformation in the backend,
rather than trying to reflect this in the view from
Scala symbols + ASTs.

We also need to add an restriction related to invokespecial to Java
parents: to support a super call to one of these to implement a
super accessor, the interface must be listed as a direct parent
of the class.

The static method names has a trailing $ added to avoid duplicate
name and signature errors in classfiles.

1 files changed, 10 insertions, 12 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeIdiomatic.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeIdiomatic.scala
index ed1b4ec325..e3d45a9b3e 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeIdiomatic.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeIdiomatic.scala
@@ -190,6 +190,7 @@ abstract class BCodeIdiomatic extends SubComponent {
         JavaStringBuilderClassName,
         INSTANCE_CONSTRUCTOR_NAME,
         "()V",
+        itf = false,
         pos
       )
     }
@@ -373,30 +374,27 @@ abstract class BCodeIdiomatic extends SubComponent {
     final def rem(tk: BType) { emitPrimitive(JCodeMethodN.remOpcodes, tk) } // can-multi-thread
 
     // can-multi-thread
-    final def invokespecial(owner: String, name: String, desc: String, pos: Position) {
-      addInvoke(Opcodes.INVOKESPECIAL, owner, name, desc, false, pos)
+    final def invokespecial(owner: String, name: String, desc: String, itf: Boolean, pos: Position): Unit = {
+      emitInvoke(Opcodes.INVOKESPECIAL, owner, name, desc, itf, pos)
     }
     // can-multi-thread
-    final def invokestatic(owner: String, name: String, desc: String, pos: Position) {
-      addInvoke(Opcodes.INVOKESTATIC, owner, name, desc, false, pos)
+    final def invokestatic(owner: String, name: String, desc: String, itf: Boolean, pos: Position): Unit = {
+      emitInvoke(Opcodes.INVOKESTATIC, owner, name, desc, itf, pos)
     }
     // can-multi-thread
-    final def invokeinterface(owner: String, name: String, desc: String, pos: Position) {
-      addInvoke(Opcodes.INVOKEINTERFACE, owner, name, desc, true, pos)
+    final def invokeinterface(owner: String, name: String, desc: String, pos: Position): Unit = {
+      emitInvoke(Opcodes.INVOKEINTERFACE, owner, name, desc, itf = true, pos)
     }
     // can-multi-thread
-    final def invokevirtual(owner: String, name: String, desc: String, pos: Position) {
-      addInvoke(Opcodes.INVOKEVIRTUAL, owner, name, desc, false, pos)
+    final def invokevirtual(owner: String, name: String, desc: String, pos: Position): Unit = {
+      emitInvoke(Opcodes.INVOKEVIRTUAL, owner, name, desc, itf = false, pos)
     }
 
-    private def addInvoke(opcode: Int, owner: String, name: String, desc: String, itf: Boolean, pos: Position) = {
+    def emitInvoke(opcode: Int, owner: String, name: String, desc: String, itf: Boolean, pos: Position): Unit = {
       val node = new MethodInsnNode(opcode, owner, name, desc, itf)
       jmethod.instructions.add(node)
       if (settings.optInlinerEnabled) callsitePositions(node) = pos
     }
-    final def invokedynamic(owner: String, name: String, desc: String) {
-      jmethod.visitMethodInsn(Opcodes.INVOKEDYNAMIC, owner, name, desc)
-    }
 
     // can-multi-thread
     final def goTo(label: asm.Label) { jmethod.visitJumpInsn(Opcodes.GOTO, label) }