Proposal to Deprecate macOS Intel Support in ITK 6 (Retain in ITK 5)

Engineering
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Proposal

Deprecate macOS Intel (x86_64) support in ITK 6, while maintaining it in ITK 5 as a long-term support (LTS) release. This aligns with Apple’s phased sunsetting of Intel Macs and industry-wide shifts toward Apple Silicon optimization.

Rationale

1. Apple’s Official Transition Timeline

  • Apple completed its transition to Apple Silicon in June 2023 with the Intel Mac Pro’s discontinuation[1].
  • macOS 17 (2026) is projected to be Apple Silicon–only, ending major OS updates for Intel Macs[2][3].
  • Security updates for Intel Macs will continue until ~2027 for newer models (e.g., 2019 iMac, Mac Pro) but lack feature parity[2:1][4].

2. Third-Party Software Trends

  • Major developers (e.g., Adobe, Microsoft) now prioritize Apple Silicon optimizations, with some dropping Intel support entirely[2:2][4:1].
  • ARM64 macOS now dominates developer toolchains, with Xcode and CI/CD pipelines increasingly excluding Intel[4:2].

3. ITK Maintenance Burden

  • Supporting legacy Intel macOS complicates builds, testing, and CI/CD for ARM64-specific optimizations.
  • macOS Intel GitHub Action Runners (macos-13) are slower than the ARM counterparts.
  • Deprecating Intel in ITK 6 allows focused resources on Apple Silicon performance.

Proposed Implementation

  • ITK 6:
    • Remove Intel macOS from build matrices.
    • Document deprecation in release notes, directing users to ITK 5 for legacy workflows.
  • ITK 5:
    • Maintain Intel macOS support as an LTS branch until 2027 (aligned with Apple’s security update window).
    • Backport critical fixes only.

Community Impact Considerations

  • Affected Users: Researchers/clinicians relying on older Intel Macs for specialized hardware (e.g., GPUs, PCIe devices).
  • Mitigation: Provide migration guides for Apple Silicon or Linux/Windows alternatives.
  • Timeline: Target deprecation for ITK 6.0 (Q1 2026), coinciding with macOS 17’s expected release[3:1].

Supporting Data

Key Fact Source
macOS 17 (2026) likely Apple Silicon–only [2:3][3:2]
Final Intel Mac (Mac Pro) discontinued June 2023 [1:1]
Security updates until ~2027 for newer Intel Macs [2:4][4:3]
Average 2-year security update window post-OS EOL [2:5][3:3][4:4]

Request for Feedback

Please share:

  1. Use cases requiring Intel macOS support beyond 2026.
  2. Concerns about legacy hardware/software dependencies.
  3. Preferences for LTS backport policies in ITK 5.

References inline via linked sources. Data current as of April 2025.

  1. Mac transition to Apple silicon - Wikipedia ↩︎ ↩︎

  2. Got an Intel Mac? Here's the deal so far, and possible future ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

  3. When will Apple stop supporting Intel Macs? - 9to5Mac ↩︎ ↩︎ ↩︎ ↩︎

  4. How Long Will Intel Macs Be Supported? - ComputerCity ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

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The discussion has started on GitHub: