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False positive overload-overlap with booleans and integer literals #20084
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
Activity
wyattscarpenter commentedon Oct 18, 2025
As a workaround, the second one will work if you use
Literal[True, False]instead ofbool(related to #14764).jorenham commentedon Oct 18, 2025
Note that ruff (pyupgrade if I remember correctly) can report this as an error (depending on your config, of course). Using literals also tends to negatively affect type-checker analysis times (although it's probably negligible in most cases). So I think that in this case I'd prefer using a classic
# type: ignore[overload-overlap]as workaround.