ruff/crates/ty_python_semantic/resources/mdtest/scopes/builtin.md

Builtin scope

Conditionally global or builtin

If a builtin name is conditionally defined as a global, a name lookup should union the builtin type with the conditionally-defined type:

def returns_bool() -> bool:
    return True

if returns_bool():
    chr: int = 1

def f():
    reveal_type(chr)  # revealed: int | (def chr(i: SupportsIndex, /) -> str)

Conditionally global or builtin, with annotation

Same is true if the name is annotated:

def returns_bool() -> bool:
    return True

if returns_bool():
    chr: int = 1

def f():
    reveal_type(chr)  # revealed: int | (def chr(i: SupportsIndex, /) -> str)