add support for django.conf.settings.SETTING_NAME

mypy_django_plugin/plugins/setup_settings.py

@@ -0,0 +1,34 @@
+from typing import cast, Any
+
+from django.conf import Settings
+from mypy.nodes import MDEF, TypeInfo, SymbolTable
+from mypy.plugin import ClassDefContext
+from mypy.semanal import SemanticAnalyzerPass2
+from mypy.types import Instance, AnyType, TypeOfAny
+
+from mypy_django_plugin import helpers
+
+
+def get_obj_type_name(value: Any) -> str:
+    return type(value).__module__ + '.' + type(value).__qualname__
+
+
+class DjangoConfSettingsInitializerHook(object):
+    def __init__(self, settings: Settings):
+        self.settings = settings
+
+    def __call__(self, ctx: ClassDefContext) -> None:
+        api = cast(SemanticAnalyzerPass2, ctx.api)
+        for name, value in self.settings.__dict__.items():
+            if name.isupper():
+                if value is None:
+                    ctx.cls.info.names[name] = helpers.create_new_symtable_node(name, MDEF,
+                                                                                instance=api.builtin_type('builtins.object'))
+                    continue
+
+                type_fullname = get_obj_type_name(value)
+                sym = api.lookup_fully_qualified_or_none(type_fullname)
+                if sym is not None:
+                    args = len(sym.node.type_vars) * [AnyType(TypeOfAny.from_omitted_generics)]
+                    ctx.cls.info.names[name] = helpers.create_new_symtable_node(name, MDEF,
+                                                                                instance=Instance(sym.node, args))