Merge pull request #950 from visualfc/println2

cl: fix print/println cmd no params call

cl/compile_test.go

@@ -3475,3 +3475,26 @@ func (p *Point) String() string {
 }
 `)
 }
+
+func TestCallPrintln(t *testing.T) {
+	gopClTest(t, `
+print
+print "hello"
+print("hello")
+println
+println "hello"
+println("hello")
+`, `package main
+
+import fmt "fmt"
+
+func main() {
+	fmt.Print()
+	fmt.Print("hello")
+	fmt.Print("hello")
+	fmt.Println()
+	fmt.Println("hello")
+	fmt.Println("hello")
+}
+`)
+}

cl/stmt.go

@@ -81,9 +81,14 @@ func compileStmt(ctx *blockCtx, stmt ast.Stmt) {
 	commentStmt(ctx, stmt)
 	switch v := stmt.(type) {
 	case *ast.ExprStmt:
-		compileExpr(ctx, v.X)
-		if canAutoCall(v.X) && isFunc(ctx.cb.InternalStack().Get(-1).Type) {
+		if obj, ok := isBuiltinAutoCall(ctx, v.X); ok {
+			ctx.cb.Val(obj)
 			ctx.cb.Call(0)
+		} else {
+			compileExpr(ctx, v.X)
+			if canAutoCall(v.X) && isFunc(ctx.cb.InternalStack().Get(-1).Type) {
+				ctx.cb.Call(0)
+			}
 		}
 	case *ast.AssignStmt:
 		compileAssignStmt(ctx, v)
@@ -142,6 +147,19 @@ retry:
 	return false
 }
 
+func isBuiltinAutoCall(ctx *blockCtx, expr ast.Expr) (types.Object, bool) {
+	if ident, ok := expr.(*ast.Ident); ok {
+		switch ident.Name {
+		case "print", "println":
+			_, builtin := lookupType(ctx, ident.Name)
+			if isBuiltin(builtin) {
+				return builtin, true
+			}
+		}
+	}
+	return nil, false
+}
+
 func compileReturnStmt(ctx *blockCtx, expr *ast.ReturnStmt) {
 	var n = -1
 	var results *types.Tuple