Fix PartialType-related crash in --strict-optional

mypy/checker.py

@@ -2247,7 +2247,8 @@ def leave_partial_types(self) -> None:
         partial_types = self.partial_types.pop()
         if not self.current_node_deferred:
             for var, context in partial_types.items():
-                if experiments.STRICT_OPTIONAL and cast(PartialType, var.type).type is None:
+                if (experiments.STRICT_OPTIONAL and
+                        isinstance(var.type, PartialType) and var.type.type is None):
                     # None partial type: assume variable is intended to have type None
                     var.type = NoneTyp()
                 else:

mypy/checkexpr.py

@@ -157,8 +157,10 @@ def try_infer_partial_type(self, e: CallExpr) -> None:
             var = cast(Var, e.callee.expr.node)
             partial_types = self.chk.find_partial_types(var)
             if partial_types is not None and not self.chk.current_node_deferred:
-                partial_type = cast(PartialType, var.type)
-                if partial_type is None or partial_type.type is None:
+                partial_type = var.type
+                if (partial_type is None or
+                        not isinstance(partial_type, PartialType) or
+                        partial_type.type is None):
                     # A partial None type -> can't infer anything.
                     return
                 typename = partial_type.type.fullname()

test-data/unit/check-optional.test

@@ -315,3 +315,18 @@ x = f  # type: Callable[[], None]
 [case testOptionalCallable]
 from typing import Callable, Optional
 T = Optional[Callable[..., None]]
+
+[case testAnyTypeInPartialTypeList]
+# options: check_untyped_defs
+def f(): ...
+
+def lookup_field(name, obj):
+    try:
+        pass
+    except:
+        attr = f()
+    else:
+        attr = None
+[out]
+main: note: In function "lookup_field":
+main:10: error: Need type annotation for variable