Function _verify_signature

mypy/stubtest.py:1108–1224

(
    stub: Signature[nodes.Argument],
    runtime: Signature[inspect.Parameter],
    function_name: str,
    warn_runtime_is_object_init: bool = False,
)

def _verify_signature(
    stub: Signature[nodes.Argument],
    runtime: Signature[inspect.Parameter],
    function_name: str,
    warn_runtime_is_object_init: bool = False,
) -> Iterator[str]:
    # Check positional arguments match up
    for stub_arg, runtime_arg in zip(stub.pos, runtime.pos):
        yield from _verify_arg_name(stub_arg, runtime_arg, function_name)
        yield from _verify_arg_default_value(stub_arg, runtime_arg)
        if (
            runtime_arg.kind == inspect.Parameter.POSITIONAL_ONLY
            and not stub_arg.pos_only
            and not stub_arg.variable.name.startswith("__")
            and stub_arg.variable.name.strip("_") != "self"
            and stub_arg.variable.name.strip("_") != "cls"
        ):
            yield (
                f'stub parameter "{stub_arg.variable.name}" should be positional-only '
                f'(add "/", e.g. "{runtime_arg.name}, /")'
            )
        if (
            runtime_arg.kind != inspect.Parameter.POSITIONAL_ONLY
            and (stub_arg.pos_only or stub_arg.variable.name.startswith("__"))
            and not runtime_arg.name.startswith("__")
            and stub_arg.variable.name.strip("_") != "self"
            and stub_arg.variable.name.strip("_") != "cls"
            and not is_dunder(function_name, exclude_special=True)  # noisy for dunder methods
        ):
            yield (
                f'stub parameter "{stub_arg.variable.name}" should be positional or keyword '
                '(remove "/")'
            )

    # Check unmatched positional args
    if len(stub.pos) > len(runtime.pos):
        # There are cases where the stub exhaustively lists out the extra parameters the function
        # would take through *args. Hence, a) if runtime accepts *args, we don't check whether the
        # runtime has all of the stub's parameters, b) below, we don't enforce that the stub takes
        # *args, since runtime logic may prevent arbitrary arguments from actually being accepted.
        if runtime.varpos is None:
            for stub_arg in stub.pos[len(runtime.pos) :]:
                # If the variable is in runtime.kwonly, it's just mislabelled as not a
                # keyword-only argument
                if stub_arg.variable.name not in runtime.kwonly:
                    msg = f'runtime does not have parameter "{stub_arg.variable.name}"'
                    if runtime.varkw is not None:
                        msg += ". Maybe you forgot to make it keyword-only in the stub?"
                    elif warn_runtime_is_object_init:
                        msg += ". You may need to write stubs for __new__ instead of __init__."
                    yield msg
                else:
                    yield f'stub parameter "{stub_arg.variable.name}" is not keyword-only'
            if stub.varpos is not None:
                yield f'runtime does not have *args parameter "{stub.varpos.variable.name}"'
    elif len(stub.pos) < len(runtime.pos):
        for runtime_arg in runtime.pos[len(stub.pos) :]:
            if runtime_arg.name not in stub.kwonly: