Added support for including symbols in lists.

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/unary/CastListNode.java

@@ -41,6 +41,7 @@ import com.oracle.truffle.r.runtime.data.RNull;
 import com.oracle.truffle.r.runtime.data.RPairList;
 import com.oracle.truffle.r.runtime.data.RS4Object;
 import com.oracle.truffle.r.runtime.data.RStringVector;
+import com.oracle.truffle.r.runtime.data.RSymbol;
 import com.oracle.truffle.r.runtime.data.model.RAbstractVector;
 import com.oracle.truffle.r.runtime.env.REnvironment;
 
@@ -137,6 +138,11 @@ public abstract class CastListNode extends CastBaseNode {
         return RDataFactory.createList(new Object[]{o});
     }
 
+    @Specialization
+    protected RList doRSymbol(RSymbol s) {
+        return RDataFactory.createList(new Object[]{s});
+    }
+
     public static CastListNode create() {
         return CastListNodeGen.create(true, true, true);
     }

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/unary/PrecedenceNode.java

@@ -46,6 +46,7 @@ import com.oracle.truffle.r.runtime.data.RRaw;
 import com.oracle.truffle.r.runtime.data.RRawVector;
 import com.oracle.truffle.r.runtime.data.RS4Object;
 import com.oracle.truffle.r.runtime.data.RStringVector;
+import com.oracle.truffle.r.runtime.data.RSymbol;
 import com.oracle.truffle.r.runtime.env.REnvironment;
 import com.oracle.truffle.r.runtime.nodes.RBaseNode;
 
@@ -202,6 +203,11 @@ public abstract class PrecedenceNode extends RBaseNode {
         return LIST_PRECEDENCE;
     }
 
+    @Specialization
+    protected int doS4Object(RSymbol o, byte recursive) {
+        return LIST_PRECEDENCE;
+    }
+
     @Specialization(guards = {"recursive == LOGICAL_FALSE", "args.getLength() == 1"})
     protected int doArgsValuesAndNames(RArgsValuesAndNames args, byte recursive, @Cached("createRecursive()") PrecedenceNode precedenceNode) {
         return precedenceNode.executeInteger(args.getArgument(0), recursive);

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

@@ -541,6 +541,8 @@ public class TestBuiltin_c extends TestBase {
         assertEval("{ e1 <- new.env(), c(e1, 3) }");
 
         assertEval("{ setClass(\"foo\", representation(d=\"numeric\")); x<-new(\"foo\", d=42); y<-c(x, 7); y[[1]] }");
+
+        assertEval("{ typeof(c(as.symbol(\"foo\"), 42)) }");
     }
 
     @Test