fix miswork on TypeVar arguments

Snowapril · Snowapril · commit 0cf8b3a36d8f · 2021-10-25T22:39:22.000+09:00
Signed-off-by: snowapril &lt;sinjihng@gmail.com&gt;
diff --git a/vm/src/builtins/genericalias.rs b/vm/src/builtins/genericalias.rs
@@ -204,24 +204,24 @@ fn subs_tvars(
     argitems: &[PyObjectRef],
     vm: &VirtualMachine,
 ) -> PyResult {
-    let sub_params = obj.clone().get_attr("__parameters__", vm)?;
-    if let Ok(sub_params) = PyTupleRef::try_from_object(vm, sub_params) {
-        let sub_args = sub_params
-            .as_slice()
-            .iter()
-            .map(|arg| {
-                if let Some(idx) = tuple_index(params, arg) {
-                    argitems[idx].clone()
-                } else {
-                    arg.clone()
-                }
-            })
-            .collect::<Vec<_>>();
-        let sub_args: PyObjectRef = PyTuple::new_ref(sub_args, &vm.ctx).into();
-        obj.get_item(sub_args, vm)
-    } else {
-        Ok(obj)
+    if let Some(sub_params) = obj.class().get_attr("__parameters__") {
+        if let Ok(sub_params) = PyTupleRef::try_from_object(vm, sub_params) {
+            let sub_args = sub_params
+                .as_slice()
+                .iter()
+                .map(|arg| {
+                    if let Some(idx) = tuple_index(params, arg) {
+                        argitems[idx].clone()
+                    } else {
+                        arg.clone()
+                    }
+                })
+                .collect::<Vec<_>>();
+            let sub_args: PyObjectRef = PyTuple::new_ref(sub_args, &vm.ctx).into();
+            return obj.get_item(sub_args, vm);
+        }
     }
+    Ok(obj)
 }
 
 impl AsMapping for PyGenericAlias {
