[Truffle] Implement the basics of Kernel#__callee__.

Author: eregon

spec/truffle/tags/core/kernel/__callee___tags.txt

@@ -1,9 +1,6 @@
 fails:Kernel.__callee__ returns the current method, even when aliased
 fails:Kernel.__callee__ returns the aliased name when aliased method
 fails:Kernel.__callee__ returns the caller from blocks too
-fails:Kernel.__callee__ returns the caller from define_method too
-fails:Kernel.__callee__ returns the caller from block inside define_method too
-fails:Kernel.__callee__ returns the caller from a define_method called from the same class
 fails:Kernel.__callee__ returns method name even from eval
 fails:Kernel.__callee__ returns nil when not called from a method
 fails:Kernel.__callee__ returns the caller when sent as a string

spec/truffle/tags/core/kernel/__method___tags.txt

@@ -1,5 +1,3 @@
-fails:Kernel.__method__ returns the caller from define_method too
-fails:Kernel.__method__ returns the caller from block inside define_method too
 fails:Kernel.__method__ returns method name even from eval
 fails:Kernel.__method__ returns nil from inside a class body
 fails:Kernel.__method__ returns nil when not called from a method

truffle/src/main/java/org/jruby/truffle/nodes/core/KernelNodes.java

@@ -353,6 +353,25 @@ public boolean blockGiven() {
         }
     }
 
+    @CoreMethod(names = "__callee__", needsSelf = false)
+    public abstract static class CalleeNameNode extends CoreMethodNode {
+
+        public CalleeNameNode(RubyContext context, SourceSection sourceSection) {
+            super(context, sourceSection);
+        }
+
+        public CalleeNameNode(CalleeNameNode prev) {
+            super(prev);
+        }
+
+        @Specialization
+        public RubySymbol calleeName(VirtualFrame frame) {
+            notDesignedForCompilation();
+            // the "called name" of a method.
+            return getContext().getSymbolTable().getSymbol(RubyCallStack.getCallingMethod(frame).getName());
+        }
+    }
+
     @CoreMethod(names = "caller", isModuleFunction = true, optional = 1)
     public abstract static class CallerNode extends CoreMethodNode {
 
@@ -1287,6 +1306,7 @@ public MethodNameNode(MethodNameNode prev) {
         @Specialization
         public RubySymbol methodName(VirtualFrame frame) {
             notDesignedForCompilation();
+            // the "original/definition name" of the method.
             return getContext().getSymbolTable().getSymbol(RubyCallStack.getCallingMethod(frame).getSharedMethodInfo().getName());
         }