ENH: Add ITK_FREEZE_REMOTE_MODULES option to prevent remote module updates

[Copilot]

Description

Developers modifying remote modules lose changes when CMake reconfigures and updates modules to upstream versions. Setting Module_<name>_GIT_TAG for each module is cumbersome with multiple remotes.

Changes

• Added ITK_FREEZE_REMOTE_MODULES CMake option in ITKModuleRemote.cmake

  • Default: OFF, marked advanced
  • Prevents git fetch/update on existing remote modules
  • New modules still clone normally (intentional)

• Modified itk_fetch_module() in ITKModuleRemote.cmake

  • Check runs after Module_<name>_GIT_TAG override processing
  • Precedence: ITK_FORBID_DOWNLOADS > Module_<name>_GIT_TAG > ITK_FREEZE_REMOTE_MODULES > empty tag check
  • Status message logged when skipping updates

• Updated Modules/Remote/README.md

  • New "Working with Modified Remote Modules" section
  • Documents both global freeze and per-module override patterns

Usage

# Freeze all remote modules
cmake -DITK_FREEZE_REMOTE_MODULES=ON /path/to/ITK

# Per-module override still works (takes precedence)
cmake -DITK_FREEZE_REMOTE_MODULES=ON \
      -DModule_Montage_GIT_TAG="" \
      /path/to/ITK

PR Checklist

• No API changes were made (or the changes have been approved)
• No major design changes were made (or the changes have been approved)
• Added test (or behavior not changed)
• Updated API documentation (or API not changed)
• Added license to new files (if any)
• Added Python wrapping to new files (if any) as described in ITK Software Guide Section 9.5
• Added ITK examples for all new major features (if any)

Original prompt

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This section details on the original issue you should resolve

<issue_title>Improve workflow of updating remote modules</issue_title>
<issue_description>Updating remote modules is cumbersome. Brad made a nice suggestion to improve the situation. It would be good if someone implemented it. I am repeating it here:

To prevent the remote's hash to reverting to what is upstream, set CMake variables Module_XXX_GIT_TAG. In one of my local builds I have Module_MinimalPathExtraction_GIT_TAG set to e43a18f43272bea8c9de5ded7846efbffc81f0ad and Module_Montage_GIT_TAG set to 9aafc48520b2cac963f0f1dfad97b32ed9ab89cf.

That can be cumbersome with multiple remotes being modified... Ideally a flag not to update any of them would be ideal. 🤔
</issue_description>

<agent_instructions>Implement the requested feature by appropriately modifying CMake code in this repository.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Improve workflow of updating remote modules #5742

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[dzenanz]

Can you give this a try Brad?

[blowekamp]

The changes seem to work for me.

[hjmjohnson]

Yippie! I've been thinking that this was needed for many years! Thank you for getting it put into place!