Fix AttributeError in _patch_mistral_regex when fix_mistral_regex=True #45317
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mohdfaour03 wants to merge 2 commits intohuggingface:mainfrom
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Fix AttributeError in _patch_mistral_regex when fix_mistral_regex=True #45317mohdfaour03 wants to merge 2 commits intohuggingface:mainfrom
mohdfaour03 wants to merge 2 commits intohuggingface:mainfrom
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itazap
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Apr 9, 2026
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Thanks for fixing! let's just add a small test with passing fix_mistral_reegex=True so that we catch this next time 😊
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[For maintainers] Suggested jobs to run (before merge) run-slow: auto |
The existing test only checks that passing fix_mistral_regex=True doesn't error, but the hub model's config version causes early return so the patching logic is never exercised. This new test creates a local config with an old transformers_version to force the patching code path, verifying that the pre_tokenizer is correctly patched to a Sequence without AttributeError.
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View the CircleCI Test Summary for this PR: https://huggingface.co/spaces/transformers-community/circle-ci-viz?pr=45317&sha=93b05c |
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@itazap Added a test that calls |
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Apr 9, 2026
| with tempfile.TemporaryDirectory() as tmp_dir: | ||
| config_path = os.path.join(tmp_dir, "config.json") | ||
| with open(config_path, "w", encoding="utf-8") as f: | ||
| json.dump({"model_type": "mistral", "transformers_version": "4.50.0"}, f) |
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I dont think we need a v4 pin here, it still fails in v5 no?
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This was referenced Apr 21, 2026
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Fixes #45081
Problem
Loading a Mistral tokenizer with
fix_mistral_regex=Truecrashes because_patch_mistral_regexreceives a rawtokenizers.Tokenizerbut tries toaccess
.backend_tokenizer.pre_tokenizeron it — that attribute only existson
PreTrainedTokenizerFast.Fix
Removed the
.backend_tokenizerindirection (3 lines) since the tokenizerpassed in is already the backend tokenizer.
AI tools helped locate the bug. I reviewed and understood the fix.
Before submitting
Pull Request section?
to it if that's the case. Answer : Issue _patch_mistral_regex crashes with AttributeError: 'tokenizers.Tokenizer' object has no attribute 'backend_tokenizer' when loading Mistral tokenizer with fix_mistral_regex=True #45081
Who can review?
@ArthurZucker @itazap (tokenizers)