fix argument evaluation when calling variadic functions

fixes #171

eval.go

@@ -1278,8 +1278,7 @@ func (st *Runtime) evaluateArgs(fnType reflect.Type, args CallArgs, pipedArg *re
 		}
 	}
 
-	slot, i := 0, 0
-	var term reflect.Value
+	slot := 0 // index in argument values (evaluated expressions combined with piped argument if applicable)
 
 	if !args.HasPipeSlot && pipedArg != nil {
 		in := fnType.In(slot)
@@ -1290,8 +1289,11 @@ func (st *Runtime) evaluateArgs(fnType reflect.Type, args CallArgs, pipedArg *re
 		slot++
 	}
 
-	for i < len(args.Exprs) {
+	i := 0 // index in parsed argument expression list
+
+	for slot < numArgsRequired {
 		in := fnType.In(slot)
+		var term reflect.Value
 		if args.Exprs[i].Type() == NodeUnderscore {
 			term = *pipedArg
 		} else {
@@ -1308,6 +1310,7 @@ func (st *Runtime) evaluateArgs(fnType reflect.Type, args CallArgs, pipedArg *re
 	if isVariadic {
 		in := fnType.In(numArgsRequired).Elem()
 		for i < len(args.Exprs) {
+			var term reflect.Value
 			if args.Exprs[i].Type() == NodeUnderscore {
 				term = *pipedArg
 			} else {

eval_test.go

@@ -162,8 +162,13 @@ func TestEvalActionNode(t *testing.T) {
 		"José Santos", "[email protected]",
 	})
 
+	data.Set("print", fmt.Sprint)
+	data.Set("printf", fmt.Sprintf)
+
 	RunJetTest(t, nil, nil, "actionNode", `hello {{"world"}}`, `hello world`)
 	RunJetTest(t, data, nil, "actionNode_func", `hello {{lower: "WORLD"}}`, `hello world`)
+	RunJetTest(t, data, nil, "actionNode_func_variadic", `{{ print("hello world") }}`, `hello world`)
+	RunJetTest(t, data, nil, "actionNode_func_variadic2", `{{ printf("hello %s", "world") }}`, `hello world`)
 	RunJetTest(t, data, nil, "actionNode_funcPipe", `hello {{lower: "WORLD" |upper}}`, `hello WORLD`)
 	RunJetTest(t, data, nil, "actionNode_funcPipe_parens", `{{ "foo" | repeat(2) }}`, `foofoo`)
 	RunJetTest(t, data, nil, "actionNode_funcPipe_parens2", `hello {{lower ( "WORLD" ) |upper}}`, `hello WORLD`)