fix self

pydantic/fields.py

@@ -383,15 +383,15 @@ class MyModel(pydantic.BaseModel):
             return cls(annotation=annotation, default=default, frozen=final or None)
 
     @classmethod
-    def merge_field_infos(cls, *field_infos: typing_extensions.Self, **overrides: Any) -> typing_extensions.Self:
+    def merge_field_infos(cls, *field_infos: FieldInfo, **overrides: Any) -> typing_extensions.Self:
         """Merge `FieldInfo` instances keeping only explicitly set attributes.
 
         Later `FieldInfo` instances override earlier ones.
 
         Returns:
             FieldInfo: A merged FieldInfo instance.
         """
-        flattened_field_infos: list[typing_extensions.Self] = []
+        flattened_field_infos: list[FieldInfo] = []
         for field_info in field_infos:
             flattened_field_infos.extend(x for x in field_info.metadata if isinstance(x, FieldInfo))
             flattened_field_infos.append(field_info)
@@ -402,7 +402,7 @@ def merge_field_infos(cls, *field_infos: typing_extensions.Self, **overrides: An
             field_info._attributes_set.update(overrides)
             for k, v in overrides.items():
                 setattr(field_info, k, v)
-            return field_info
+            return field_info  # type: ignore
 
         new_kwargs: dict[str, Any] = {}
         metadata = {}