Repository: huggingface/transformers
Pull request: Initialize flash attn flag

_flash_supports_window_size is used further down in this file and relied on by e.g. [ring-flash-attention](https://github.com/zhuzilin/ring-flash-attention/blob/123f924/ring_flash_attn/adapters/hf_adapter.py#L9-L11). Even though it is an unexported name, it still makes sense to keep the state of `globals()` in this file consistent.

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Changed files:
filename: src/transformers/modeling_flash_attention_utils.py
patch: @@ -46,6 +46,9 @@
     from .integrations.npu_flash_attention import npu_flash_attn_varlen_func as flash_attn_varlen_func
 
 
+_flash_supports_window_size = False
+
+
 if flash_attn_func:
     _flash_supports_window_size = "window_size" in list(inspect.signature(flash_attn_func).parameters)