🐯 is_liger_kernel_available with min version

[qgallouedec]

From @lewtun

FYI I just install trl@main and got this from trying to run GRPO:

Traceback (most recent call last):
  File "/fsx/lewis/git/hf/dev/open-r1/openr1/bin/trl", line 4, in <module>
    from trl.cli import main
  File "/fsx/lewis/git/hf/dev/open-r1/openr1/lib/python3.11/site-packages/trl/cli.py", line 24, in <module>
    from .scripts.grpo import make_parser as make_grpo_parser
  File "/fsx/lewis/git/hf/dev/open-r1/openr1/lib/python3.11/site-packages/trl/scripts/grpo.py", line 22, in <module>
    from trl import GRPOConfig, GRPOTrainer, ModelConfig, ScriptArguments, TrlParser, get_peft_config
  File "<frozen importlib._bootstrap>", line 1229, in _handle_fromlist
  File "/fsx/lewis/git/hf/dev/open-r1/openr1/lib/python3.11/site-packages/trl/import_utils.py", line 127, in __getattr__
    value = getattr(module, name)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/fsx/lewis/git/hf/dev/open-r1/openr1/lib/python3.11/site-packages/trl/import_utils.py", line 126, in __getattr__
    module = self._get_module(self._class_to_module[name])
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/fsx/lewis/git/hf/dev/open-r1/openr1/lib/python3.11/site-packages/trl/import_utils.py", line 138, in _get_module
    raise RuntimeError(
RuntimeError: Failed to import trl.trainer.grpo_trainer because of the following error (look up to see its traceback):
cannot import name 'LigerFusedLinearGRPOLoss' from 'liger_kernel.chunked_loss' (/fsx/lewis/git/hf/dev/open-r1/openr1/lib/python3.11/site-packages/liger_kernel/chunked_loss/__init__.py)

The solution is to bump liger-kernel like here but it's odd that doing a new install of trl didn't catch this (I had an older version of liger installed)

From me:

I think it's because you did pip install trl and not pip install trl[liger]. Maybe the solution to avoid this is to also check the version in is_liger_available (returns True only if the min version is installed) , and more generally in all is_xxx_availalbe.

---

I suggest the following solution. Now when you run is_liger_kernel_available without the min version, it returns False.

1. It's a shame that you have to specify the min version in two places (setup.py and import_utils.py), but I can't think of any other easy and readable way to do it.

2. This implementation actually matches that of transformers, which, as everyone knows, is the source of all truth 🙇: https://github.com/huggingface/transformers/blob/main/src/transformers/utils/import_utils.py

3. We could do this with all our optional dependencies. But it's a bit time-consuming, so I'll leave it to follow-up PRs.

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[lewtun]

Thanks for the fix, LGTM!