Do not copy node type in ast.Patch

Fixes #468

ast/node.go

@@ -17,7 +17,6 @@ type Node interface {
 }
 
 func Patch(node *Node, newNode Node) {
- newNode.SetType((*node).Type())
  newNode.SetLocation((*node).Location())
  *node = newNode
 }

checker/checker.go

@@ -536,6 +536,14 @@ func (v *checker) SliceNode(node *ast.SliceNode) (reflect.Type, info) {
 }
 
 func (v *checker) CallNode(node *ast.CallNode) (reflect.Type, info) {
+ t, i := v.functionReturnType(node)
+ if node.Type() != nil {
+ return node.Type(), i
+ }
+ return t, i
+}
+
+func (v *checker) functionReturnType(node *ast.CallNode) (reflect.Type, info) {
  fn, fnInfo := v.visit(node.Callee)
 
  if fnInfo.fn != nil {

test/patch/set_type/set_type_test.go

@@ -0,0 +1,56 @@
+package set_type_test
+
+import (
+ "reflect"
+ "testing"
+
+ "github.com/stretchr/testify/require"
+
+ "github.com/antonmedv/expr"
+ "github.com/antonmedv/expr/ast"
+)
+
+func TestPatch_SetType(t *testing.T) {
+ _, err := expr.Compile(
+ `Value + "string"`,
+ expr.Env(Env{}),
+ expr.Function(
+ "getValue",
+ func(params ...any) (any, error) {
+ return params[0].(Value).Int, nil
+ },
+ // We can set function type right here,
+ // but we want to check what SetType in
+ // getValuePatcher will take an effect.
+ ),
+ expr.Patch(getValuePatcher{}),
+ )
+ require.Error(t, err)
+}
+
+type Value struct {
+ Int int
+}
+
+type Env struct {
+ Value Value
+}
+
+var valueType = reflect.TypeOf((*Value)(nil)).Elem()
+
+type getValuePatcher struct{}
+
+func (getValuePatcher) Visit(node *ast.Node) {
+ id, ok := (*node).(*ast.IdentifierNode)
+ if !ok {
+ return
+ }
+ if id.Type() == valueType {
+ newNode := &ast.CallNode{
+ Callee: &ast.IdentifierNode{Value: "getValue"},
+ Arguments: []ast.Node{id},
+ }
+ newNode.SetType(reflect.TypeOf(0))
+ ast.Patch(node, newNode)
+ }
+}