Fix dec

sqlmypy.py

@@ -1,15 +1,16 @@
+from mypy.mro import calculate_mro, MroError
 from mypy.plugin import Plugin, FunctionContext, ClassDefContext
 from mypy.plugins.common import add_method
 from mypy.nodes import(
     NameExpr, Expression, StrExpr, TypeInfo, ClassDef, Block, SymbolTable, SymbolTableNode, GDEF,
-    Argument, Var, ARG_STAR2, MDEF
+    Argument, Var, ARG_STAR2, MDEF, TupleExpr
 )
 from mypy.types import (
     UnionType, NoneTyp, Instance, Type, AnyType, TypeOfAny, UninhabitedType, CallableType
 )
 from mypy.typevars import fill_typevars_with_any
 
-from typing import Optional, Callable, Dict, TYPE_CHECKING
+from typing import Optional, Callable, Dict, TYPE_CHECKING, List
 if TYPE_CHECKING:
     from typing_extensions import Final
 
@@ -141,14 +142,30 @@ def decl_info_hook(ctx):
 
         Base = declarative_base()
     """
+    cls_instances = []  # type: List[Instance]
+
+    if 'cls' in ctx.call.arg_names:
+        declarative_base_cls_arg = ctx.call.args[ctx.call.arg_names.index("cls")]
+        if isinstance(declarative_base_cls_arg, TupleExpr):
+            cls_instances = [Instance(item.node, []) for item in declarative_base_cls_arg.items]
+        else:
+            cls_instances = [Instance(declarative_base_cls_arg.node, [])]
+
     class_def = ClassDef(ctx.name, Block([]))
     class_def.fullname = ctx.api.qualified_name(ctx.name)
 
     info = TypeInfo(SymbolTable(), class_def, ctx.api.cur_mod_id)
     class_def.info = info
     obj = ctx.api.builtin_type('builtins.object')
-    info.mro = [info, obj.type]
-    info.bases = [obj]
+    info.bases = cls_instances + [obj]
+    try:
+        calculate_mro(info)
+    except MroError:
+        ctx.api.errors.report(ctx.get_line(), ctx.get_column(), "Not able to calculate MRO for declarative base",
+                              blocker=False)
+        info.bases = [obj]
+        info.fallback_to_any = True
+
     ctx.api.add_symbol_table_node(ctx.name, SymbolTableNode(GDEF, info))
     set_declarative(info)