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Inconsistent feeling handling of Any in binder #20870
Description
from typing import Any, Final
CONSTANT: Final = 2015
def good(result: dict[str, Any]) -> None:
code = 'asdf'
if isinstance(result, dict):
code = result.get('code', code)
reveal_type(code) # N: Revealed type is "Any"
if code == CONSTANT:
reveal_type(code) # N: Revealed type is "Any"
def bad(result: Any) -> None:
code = 'asdf'
if isinstance(result, dict):
code = result.get('code', code)
reveal_type(code) # N: Revealed type is "builtins.str"
if code == CONSTANT:
reveal_type(code) # N: Revealed type is "builtins.str"
Based on real world code for rotki
This feels a little inconsistent / violating of gradual typing
Not exactly sure what if anything we should do, though
Found this via #20660 which makes --warn-unreachable flag raise a diagnostic on the second comparison
Activity
ilevkivskyi commentedon Feb 23, 2026
I vaguely remember discussion with @cdce8p about this, and IIRC he said that your
bad()is actually good (and vice versa). The current behavior w.r.t.Anyin binder is a result of many compromises. At some point I tried to make it proper and principled (which is actually not hard by itself), but I lost, because people were not happy with getting more possible false negatives.ilevkivskyi commentedon Feb 23, 2026
Btw this works (much) better with
--allow-redefinition-new. For last two reveals I am gettingMatch typeshed dict.get in fixtures (#20871)