stubtest: handle name mangling

Author: hauntsaninja

mypy/stubtest.py

@@ -241,9 +241,12 @@ def verify_typeinfo(
     to_check.update(m for m in cast(Any, vars)(runtime) if not m.startswith("_"))
 
     for entry in sorted(to_check):
+        mangled_entry = entry
+        if entry.startswith("__") and not entry.endswith("__"):
+            mangled_entry = "_{}{}".format(stub.name, entry)
         yield from verify(
             next((t.names[entry].node for t in stub.mro if entry in t.names), MISSING),
-            getattr(runtime, entry, MISSING),
+            getattr(runtime, mangled_entry, MISSING),
             object_path + [entry],
         )
 
@@ -267,7 +270,13 @@ def _verify_static_class_methods(
     # Look the object up statically, to avoid binding by the descriptor protocol
     static_runtime = importlib.import_module(object_path[0])
     for entry in object_path[1:]:
-        static_runtime = inspect.getattr_static(static_runtime, entry)
+        try:
+            static_runtime = inspect.getattr_static(static_runtime, entry)
+        except AttributeError:
+            # This can happen with mangled names, ignore for now.
+            # TODO: pass more information about ancestors of nodes/objects to verify, so we don't
+            # have to do this hacky lookup. Would be useful in a couple other places too.
+            return
 
     if isinstance(static_runtime, classmethod) and not stub.is_class:
         yield "runtime is a classmethod but stub is not"

mypy/test/teststubtest.py

@@ -572,6 +572,22 @@ def h(x: str): ...
         yield Case(stub="", runtime="__all__ += ['y']\ny = 5", error="y")
         yield Case(stub="", runtime="__all__ += ['g']\ndef g(): pass", error="g")
 
+    @collect_cases
+    def test_name_mangling(self) -> Iterator[Case]:
+        yield Case(
+            stub="""
+            class X:
+                def __mangle_good(self, text: str) -> None: ...
+                def __mangle_bad(self, number: int) -> None: ...
+            """,
+            runtime="""
+            class X:
+                def __mangle_good(self, text): pass
+                def __mangle_bad(self, text): pass
+            """,
+            error="X.__mangle_bad"
+        )
+
 
 def remove_color_code(s: str) -> str:
     return re.sub("\\x1b.*?m", "", s)  # this works!