Fix TypeError in convert_rope_params_to_dict when ignore_keys is a list

[hangjun-ezra]

What does this PR do?

Fixes a TypeError: unsupported operand type(s) for |: 'list' and 'set' in RotaryEmbeddingConfigMixin.convert_rope_params_to_dict when ignore_keys_at_rope_validation is a list instead of a set.

Root cause

In modeling_rope_utils.py line 649, the else branch passes through ignore_keys_at_rope_validation without type coercion. Line 651 then performs ignore_keys_at_rope_validation | {"partial_rotary_factor"}, which fails if the value is a list (since list | set is not supported in Python).

When does this happen?

Model configs define ignore_keys_at_rope_validation as a set literal in __init__, so the normal from_pretrained flow works. However, when third-party serving frameworks (e.g. vLLM) define their own config classes that pass this field through JSON deserialization, the value arrives as a list, triggering the crash.

Encountered in practice when serving Qwen3.5-27B via vLLM (which bundles its own Qwen3_5TextConfig that inherits from PretrainedConfig).

Fix

Wrap in set() to normalize any iterable. set(already_a_set) returns a copy, so existing behavior is preserved.

- set() if ignore_keys_at_rope_validation is None else ignore_keys_at_rope_validation
+ set() if ignore_keys_at_rope_validation is None else set(ignore_keys_at_rope_validation)

Traceback

File "transformers/modeling_rope_utils.py", line 651, in convert_rope_params_to_dict
    ignore_keys_at_rope_validation = ignore_keys_at_rope_validation | {"partial_rotary_factor"}
TypeError: unsupported operand type(s) for |: 'list' and 'set'

Full call chain: Qwen3_5TextConfig.__init__ → PretrainedConfig.__init__ → convert_rope_params_to_dict

[Rocketknight1]

hey @redpanda1995 please stop going around randomly approving PRs - it creates notifications for the maintainers, and also you're clearly not actually reviewing them because several of them were invalid! We'll just block you across all HF repos if this continues.

[Rocketknight1]

It's a bit weird to add code to support malformed calls from external frameworks, but it's very harmless (since set(set) is a no-op) so I'm willing to accept this one!

[HuggingFaceDocBuilderDev]

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