bpo-46255: Remove unnecessary check in _IOBase._check*() methods

[ghost]

These methods are METH_NOARGS, in all cases the second parameter will be NULL.

    {"_checkClosed",   _PyIOBase_check_closed, METH_NOARGS},
    {"_checkSeekable", _PyIOBase_check_seekable, METH_NOARGS},
    {"_checkReadable", _PyIOBase_check_readable, METH_NOARGS},
    {"_checkWritable", _PyIOBase_check_writable, METH_NOARGS},

https://bugs.python.org/issue46255

[encukou]

in all cases the second parameter will be NULL.

Unfortunately, that's not true. They are called from other C code as well:

cpython/Modules/_io/textio.c

Line 1485 in f232cfa

else if (_PyIOBase_check_closed((PyObject *)self, Py_True) == NULL) \

cpython/Modules/_io/bufferedio.c

Line 1242 in f232cfa

if (_PyIOBase_check_seekable(self->raw, Py_True) == NULL)

cpython/Modules/_io/bufferedio.c

Line 1437 in f232cfa

if (_PyIOBase_check_readable(raw, Py_True) == NULL)

cpython/Modules/_io/bufferedio.c

Line 1791 in f232cfa

if (_PyIOBase_check_writable(raw, Py_True) == NULL)

This would be a nice simplification if that wasn't the case!