tuple does not define __new__

[ltworf]

Reporting python/mypy#4991 here.

This code to make a subclass of tuple does not pass the test.

class A(tuple):
    def __new__(cls, fields):
        return super(A, cls).__new__(cls, tuple(fields))

With those settings:

python_version=3.5
warn_unused_ignores=True
warn_redundant_casts=True
strict_optional=True
scripts_are_modules=True
check_untyped_defs=True

Using mypy 0.590

And it results in

/tmp/test.py:3: error: Too many arguments for "__new__" of "object"

[ltworf]

It can be called with

tuple.__new__(tuple,[1,2,3])
tuple.__new__(tuple)

So I think the type should be:

    def __new__(cls: Type[_T], iterable: Iterable[Any]=tuple()) -> _T: ...

[ltworf]

Seems I did some mistake

./stdlib/3/builtins.pyi:585:56: Y011 Default values for typed arguments must be "..."
./stdlib/3/builtins.pyi:585:56: B008 Do not perform calls in argument defaults. The call is performed only once at function definition time. All calls to your function will reuse the result of that definition-time call. If this is intended, assign the function call to a module-level variable and use that variable as a default value.

The calls in default is fine, since tuple() is not mutable though.