_imp is actually only deprecated for user code, it's still heavily used in cpython internals. I think it'd probably be good to implement it in _imp (at least at some point)

@coolreader18
The part that is needed in frozen_module is _imp._override_frozen_modules_for_tests.

From grepping this function (_override_frozen_modules_for_test) in cpython repo, it is only used in frozen_modules in test/support/import_helper.py.

Instead of implementing _override_frozen_modules_for_test right now, I chosed to raise Exception if we actually use this function. And from test result, we didn't use this function at all. Following are the implementation from cpython and this PR.

cpython version

@contextlib.contextmanager
def frozen_modules(enabled=True):
    _imp._override_frozen_modules_for_tests(1 if enabled else -1)
    try:
        yield
    finally:
        _imp._override_frozen_modules_for_tests(0)

This PR

@contextlib.contextmanager
def frozen_modules(enabled=True):
    if enabled:
        raise NotImplemented("frozen_modules is not implemented on RustPython")

    yield

Compared with previous commit, this PR also doesn't change the behavior since the old commit just ignore all function called of frozen_modules. Now we add frozen_modules and check if we need _imp.override_frozen_modules_for_tests. If yes, we raise exception. If not (seems like all tests we're running now doesn't need this), it exhibit the same behavior as cpython.

it sounds reasonable to me

Oh yes, me as well, sorry I just didn't have the time to fully review the added code when I first noticed this. LGTM