Fix calls with explicit args and internal generic dispatch

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/function/RCallNode.java

@@ -359,22 +359,24 @@ public abstract class RCallNode extends RCallBaseNode implements RSyntaxNode, RS
         RBuiltinDescriptor builtin = builtinProfile.profile(function.getRBuiltin());
         RArgsValuesAndNames argAndNames = (RArgsValuesAndNames) explicitArgs.execute(frame);
 
-        Object dispatchObject = argAndNames.getArgument(0);
-
-        if (isAttributableProfile.profile(dispatchObject instanceof RAttributeStorage) && isS4Profile.profile(((RAttributeStorage) dispatchObject).isS4())) {
-            RList list = (RList) promiseHelperNode.checkEvaluate(frame, REnvironment.getRegisteredNamespace("methods").get(".BasicFunsList"));
-            // TODO create a node that looks up the name in the names attribute
-            int index = list.getElementIndexByName(builtin.getName());
-            if (index != -1) {
-                RFunction basicFun = (RFunction) list.getDataAt(index);
-                Object result = call.execute(frame, basicFun, argAndNames, null, null);
-                if (result != RRuntime.DEFERRED_DEFAULT_MARKER) {
-                    return result;
+        RStringVector type = null;
+        if (!argAndNames.isEmpty()) {
+            Object dispatchObject = argAndNames.getArgument(0);
+            if (isAttributableProfile.profile(dispatchObject instanceof RAttributeStorage) && isS4Profile.profile(((RAttributeStorage) dispatchObject).isS4())) {
+                RList list = (RList) promiseHelperNode.checkEvaluate(frame, REnvironment.getRegisteredNamespace("methods").get(".BasicFunsList"));
+                // TODO create a node that looks up the name in the names attribute
+                int index = list.getElementIndexByName(builtin.getName());
+                if (index != -1) {
+                    RFunction basicFun = (RFunction) list.getDataAt(index);
+                    Object result = call.execute(frame, basicFun, argAndNames, null, null);
+                    if (result != RRuntime.DEFERRED_DEFAULT_MARKER) {
+                        return result;
+                    }
                 }
             }
+            type = classHierarchyNode.execute(promiseHelperNode.checkEvaluate(frame, dispatchObject));
         }
 
-        RStringVector type = argAndNames.isEmpty() ? null : classHierarchyNode.execute(promiseHelperNode.checkEvaluate(frame, dispatchObject));
         S3Args s3Args;
         RFunction resultFunction;
         if (implicitTypeProfile.profile(type != null)) {

com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/builtins/TestBuiltin_docall.java

@@ -48,5 +48,7 @@ public class TestBuiltin_docall extends TestBase {
         assertEval("{ boo <- function(c) ls(parent.frame(2)); foo <- function(a,b) boo(a); bar <- function(x,z) do.call('foo', list(parse(text='goo()'),2)); bar() }");
         assertEval("{ boo <- function(c) ls(parent.frame(3)); foo <- function(a,b) boo(a); bar <- function(x,z) do.call('foo', list(parse(text='goo()'),2)); baz <- function(bazX) bar(bazX,1); baz(); }");
         assertEval("{ f1 <- function(a) ls(parent.frame(2)); f2 <- function(b) f1(b); f3 <- function(c) f2(c); f4 <- function(d) do.call('f3', list(d)); f4(42); }");
+
+        assertEval("do.call('c', list())");
     }
 }