I've searched for RET504 before opening the issue.

def outer() -> list[object]:
    @register
    async def inner() -> None:
        print(layout)

    layout = [...]
    return layout  # noqa: RET504

The rule reports the assignment to layout as unnecessary, and provides a fix by rewriting it as return [...], which will break the inner function.

The rule doesn't trigger when layout is assigned to above the definition of the inner function, however in my use-case a decorator replaces the function with an object, which is then used to define layout, mandating the assignment to layout happens below the function definition.

[tool.ruff.lint]
preview = true
explicit-preview-rules = true
select = [ "ALL" ]

VSCode extension (v2024.54.0), ruff==0.7.1