Fix #1770 (#1771)

changes/1770-selimb.md

@@ -0,0 +1 @@
+Fix false positive from mypy plugin when a class nested within a `BaseModel` is named `Model`.

pydantic/mypy.py

@@ -328,7 +328,7 @@ class PydanticModelTransformer:
         construct_arguments = [fields_set_argument] + construct_arguments
 
         obj_type = ctx.api.named_type('__builtins__.object')
-        self_tvar_name = 'Model'
+        self_tvar_name = '_PydanticBaseModel'  # Make sure it does not conflict with other names in the class
         tvar_fullname = ctx.cls.fullname + '.' + self_tvar_name
         tvd = TypeVarDef(self_tvar_name, tvar_fullname, -1, [], obj_type)
         self_tvar_expr = TypeVarExpr(self_tvar_name, tvar_fullname, [], obj_type)

tests/mypy/modules/plugin_success.py

@@ -123,3 +123,13 @@ p = AddProject(name='x', slug='y', description='z')
 
 class TypeAliasAsAttribute(BaseModel):
     __type_alias_attribute__ = Union[str, bytes]
+
+
+class NestedModel(BaseModel):
+    class Model(BaseModel):
+        id: str
+
+    model: Model
+
+
+_ = NestedModel.Model