False positive `overload-overlap` with booleans and integer literals
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bug
topic-overloads
- Dominant language
- Python
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Description
Bug Report, To Reproduce, & Actual Behaviour
The following 2 cases trigger overload-overlap, when neither of them should (see mypy Playground).
from typing import overload, Literal
@overload
def display_str_literal(val: Literal[False], /) -> Literal["BooleanFalse"]: ... # E: ... overload-overlap
@overload
def display_str_literal(val: Literal[0], /) -> Literal["Zero"]: ...
from typing import overload, Literal
@overload
def display_str_literal_2(val: bool, /) -> Literal["Boolean"]: ...
@overload
def display_str_literal_2(val: Literal[-1], /) -> Literal["NegativeOne"]: ...
- Mypy version used: 1.18.2
- Python version used: 3.12, 3.13
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 with the two reproductions in the linked mypy Playground and confirm the overload-overlap diagnostics on Python 3.12 or 3.13. Trace the type-checker path that reports overload overlap for Literal booleans and integer literals; done means both examples type-check without a false-positive diagnostic.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 39/100