Odd behavior with overload and `Any` arguments.
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Description
Bug Report
The behavior of overload is not properly matching when one of the arguments is Any.
See https://github.com/microsoft/pyright/issues/5216#issuecomment-1594046589
To Reproduce
from typing import Any, Literal, TypeVar, overload
_T = TypeVar("_T")
class A:
@overload
def method1(self, k: Literal["hi"], default: Any) -> float:
...
@overload
def method1(self, k: str, default: _T) -> Any | _T:
...
def method1(self, k: str, default: _T) -> Any | _T:
...
def func(a: A, b: list, c: Any):
v1 = a.method1("hi", [])
reveal_type(v1) # mypy: float
my_list1: list = []
v2 = a.method1("hi", my_list1)
reveal_type(v2) # mypy: Any
v3 = a.method1("hi", b)
reveal_type(v3) # mypy: Any
v4 = a.method1("hi", c)
reveal_type(v4) # mypy: Any
my_list2: list[int] = []
v5 = a.method1("hi", my_list2)
reveal_type(v5) # mypy: float```
**Expected Behavior**
All of the revealed types should have been `float`, since the first argument of each call to `method1()` is `"hi"`. This is the behavior of `pyright`, which seems to make more sense.
**Actual Behavior**
```text
overload.py:19: note: Revealed type is "builtins.float"
overload.py:23: note: Revealed type is "Any"
overload.py:26: note: Revealed type is "Any"
overload.py:29: note: Revealed type is "Any"
overload.py:33: note: Revealed type is "builtins.float"
Your Environment
- Mypy version used: 1.3
- Mypy command-line flags: None
- Mypy configuration options from
mypy.ini(and other config files): None - Python version used: 3.10
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the supplied Python reproducer with mypy 1.3 and inspect the revealed types for each overload call. Trace overload matching for Literal["hi"] when the second argument is Any or an unparameterized list; done means all five calls reveal float as expected.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100