make ast.Node return *nature.Nature (#849)

ast/node.go

@@ -15,7 +15,7 @@ var (
 type Node interface {
 	Location() file.Location
 	SetLocation(file.Location)
-	Nature() nature.Nature
+	Nature() *nature.Nature
 	SetNature(nature.Nature)
 	Type() reflect.Type
 	SetType(reflect.Type)
@@ -47,8 +47,8 @@ func (n *base) SetLocation(loc file.Location) {
 }
 
 // Nature returns the nature of the node.
-func (n *base) Nature() nature.Nature {
-	return n.nature
+func (n *base) Nature() *nature.Nature {
+	return &n.nature
 }
 
 // SetNature sets the nature of the node.

checker/checker.go

@@ -635,8 +635,7 @@ func (v *Checker) callNode(node *ast.CallNode) Nature {
 	// checker pass we should replace anyType on method node
 	// with new correct function return type.
 	if typ := node.Type(); typ != nil && typ != anyType {
-		nt := node.Nature()
-		return nt
+		return *node.Nature()
 	}
 
 	nt := v.visit(node.Callee)

checker/info.go

@@ -15,8 +15,7 @@ func FieldIndex(c *Cache, env Nature, node ast.Node) (bool, []int, string) {
 			return true, idx, n.Value
 		}
 	case *ast.MemberNode:
-		base := n.Node.Nature()
-		base = base.Deref(c)
+		base := n.Node.Nature().Deref(c)
 		if base.Kind == reflect.Struct {
 			if prop, ok := n.Property.(*ast.StringNode); ok {
 				if idx, ok := base.FieldIndex(c, prop.Value); ok {

compiler/compiler.go

@@ -1088,8 +1088,7 @@ func (c *compiler) BuiltinNode(node *ast.BuiltinNode) {
 		for i, arg := range node.Arguments {
 			c.compile(arg)
 			argType := arg.Type()
-			argNature := arg.Nature()
-			if argType.Kind() == reflect.Ptr || argNature.IsUnknown(c.ntCache) {
+			if argType.Kind() == reflect.Ptr || arg.Nature().IsUnknown(c.ntCache) {
 				if f.Deref == nil {
 					// By default, builtins expect arguments to be dereferenced.
 					c.emit(OpDeref)