ruff/crates/red_knot_python_semantic/resources/mdtest/conditional/match.md

Pattern matching

With wildcard

def _(target: int):
    match target:
        case 1:
            y = 2
        case _:
            y = 3

    reveal_type(y)  # revealed: Literal[2, 3]

Without wildcard

def _(target: int):
    match target:
        case 1:
            y = 2
        case 2:
            y = 3

    # revealed: Literal[2, 3]
    # error: [possibly-unresolved-reference]
    reveal_type(y)

Basic match

def _(target: int):
    y = 1
    y = 2

    match target:
        case 1:
            y = 3
        case 2:
            y = 4

    reveal_type(y)  # revealed: Literal[2, 3, 4]

Guard with object that implements __bool__ incorrectly

class NotBoolable:
    __bool__ = 3

def _(target: int, flag: NotBoolable):
    y = 1
    match target:
        # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
        case 1 if flag:
            y = 2
        case 2:
            y = 3

    reveal_type(y)  # revealed: Literal[1, 2, 3]