fix(huggingface): resolve the config class for eval() explicitly (#2703)

[Anai-Guo]

Fixes #2703.

Problem

download_model() imports the config class with exec() and then builds it with eval():

# torchbenchmark/util/framework/huggingface/basic_configs.py:302-304
config_cls_name = _extract_config_cls_name(HUGGINGFACE_MODELS[model_name][2])
exec(f"from transformers import {config_cls_name}")
config = eval(HUGGINGFACE_MODELS[model_name][2])

As of Python 3.13, PEP 667 makes locals() in an optimized (function) scope return an independent snapshot, so exec() writes the imported name into a dict the following eval() never reads. Every entry in HUGGINGFACE_MODELS then fails:

NameError: name 'AutoConfig' is not defined

On 3.12 and earlier, both calls shared a single locals dict, so the name happened to be visible — which is why this has gone unnoticed.

Fix

Drop the exec() and evaluate the constructor against an explicit namespace built with getattr(transformers, ...) — the same lookup the very next line already uses for the model class:

config_ns = {config_cls_name: getattr(transformers, config_cls_name)}
config = eval(HUGGINGFACE_MODELS[model_name][2], config_ns)

transformers is already imported at module level, and all seven config classes referenced by the table (AutoConfig, BertConfig, BigBirdConfig, LlamaConfig, PhiConfig, ReformerConfig, WhisperConfig) are top-level transformers exports. This also stops the import leaking into the caller's scope.

Verification

The real download_model was AST-extracted from this file and replayed over all 31 entries of HUGGINGFACE_MODELS against a stub transformers module, on both interpreters:

	Python 3.13.13	Python 3.12.10
before	0 / 31 ok — all NameError: name 'AutoConfig' is not defined	31 / 31 ok
after	31 / 31 ok	31 / 31 ok

So the failure reproduces exactly as reported on 3.13, the fix clears it, and 3.12 behaviour is unchanged.

black --line-length 88 reports the file unchanged.

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