unet Chunking not supported in coremltools>7.1 and <7.1 does not support dynamic reshape

[nighting0le01]

🐞Describing the bug

using the torch2coreml script with the --chunk-unet option would result in the following error:
AttributeError: 'CacheDoublyLinkedList' object has no attribute 'index'. This error occurred because the index attribute has been removed from the CacheDoublyLinkedList class in the latest versions of coremltools.:apple/ml-stable-diffusion#327

Stack Trace

• If applicable, please paste the complete stack trace.

To Reproduce

use coreml==7.2 and try to run https://github.com/apple/ml-stable-diffusion?tab=readme-ov-file#-converting-models-to-core-ml
python -m python_coreml_stable_diffusion.torch2coreml --convert-unet --convert-text-encoder --convert-vae-decoder --convert-safety-checker --model-version <model-version-string-from-hub> -o <output-mlpackages-directory>

# Paste Python code snippet here, complete with any required import statements.

• If the model conversion succeeds, but there is a numerical mismatch in predictions, please include the code used for comparisons.

System environment (please complete the following information):

• coremltools version:
• OS (e.g. MacOS version or Linux type):
• Any other relevant version information (e.g. PyTorch or TensorFlow version):

(Pdb) main_block.operations
<coremltools.converters.mil.mil.utils.CacheDoublyLinkedList object at 0x7fe93c0d7c70>
(Pdb) p coremltools.converters.mil.mil.utils.CacheDoublyLinkedList
*** NameError: name 'coremltools' is not defined
(Pdb) c
Traceback (most recent call last):
  File "/workspace/pixart.py", line 266, in <module>
    main()
  File "/workspace/pixart.py", line 191, in main
    op_idx, first_chunk_weights_size, total_weights_size = _get_op_idx_split_location(
  File "/opt/conda/envs/mobile_t2i/lib/python3.9/site-packages/python_coreml_stable_diffusion/chunk_mlprogram.py", line 94, in _get_op_idx_split_location
    for op in main_block.operations:
AttributeError: 'CacheDoublyLinkedList' object has no attribute 'index'

Additional context

• Add anything else about the problem here that you want to share.
• error also came when trying to conver Pixart sigma model to Coreml:https://github.com/PixArt-alpha/PixArt-sigma

[nighting0le01]

class CacheDoublyLinkedList:
    # ... [rest of your class definition] ...

    def index(self, op: Operation) -> int:
        """
        Find the index of an operation in the linked list.
        """
        cursor = self.start
        idx = 0
        while cursor is not None:
            if cursor.op == op:
                return idx
            cursor = cursor.next
            idx += 1
        raise ValueError(f"{op} is not in the list")
        
        

maybe something like this to use .index over the linked list