Changes/LLVM-17

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LLVM 17

This is a proposed Change for Fedora Linux.
This document represents a proposed Change. As part of the Changes process, proposals are publicly announced in order to receive community feedback. This proposal will only be implemented if approved by the Fedora Engineering Steering Committee.

Summary

Update all llvm sub-projects in Fedora Linux to version 17.

Owner

• Name: Tom Stellard
• Email: <tstellar@redhat.com>

Current status

• Targeted release: Fedora Linux 39
• Last updated: 2023-06-05
• [<will be assigned by the Wrangler> devel thread]
• FESCo issue: <will be assigned by the Wrangler>
• Tracker bug: <will be assigned by the Wrangler>
• Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

All llvm sub-projects in Fedora will be updated to version 17, and there will be a soname version change for the llvm libraries. Compatibility packages clang16, llvm16, and lld16 will be added to ensure that packages that currently depend on clang and llvm version 16 libraries will continue to work.

Other notable changes:

• The Clang Resource Directory will be moved from /usr/lib64/clang/17/ to /usr/lib/clang/17/ this is the location of clang's internal headers and runtime libraries like libomp and compiler-rt. Package owners of packages that read or write this directory will need to update their packages when rebuilding against/with LLVM 17. The %clang_resource_dir helper macro can be used to make this transition smoother, and packages are encouraged to update to use this macro even before the LLVM 17 update.

• Along with the Clang Resource Directory change, compiler-rt will now install its libraries into /usr/lib/clang/16/lib/$TRIPLE/ instead of /usr/lib64/clang/16/lib/

LLVM Build Schedule

We will be changing our build schedule slightly from previous Fedora releases. We will now plan to ship a release candidate in Fedora build prior to the Beta Freeze rather than waiting until after.

Important Dates

• July 28: Upstream: 17.0.0-rc1 Release
• Aug 8: Fedora: f39 branch created
• Aug 11: Upstream: 17.0.0-rc2 Release
• Aug 22: Fedora: f39 Beta Freeze
• Aug 25: Upstream: 17.0.0-rc3 Release
• Sep 8: Upstream: 17.0.0 Release
• Oct 10: Fedora: f38 Final Freeze

Plan

1. Build LLVM 17.0.0-rc1 in COPR.
2. Build LLVM 17.0.0-rc1 into a rawhide side-tag in Koji.
3. Build LLVM 17.0.0-rc1 into a f39 side-tag in Koji.
4. Build LLVM 17.0.0-rc2 into a rawhide side-tag in Koji.
5. Build LLVM 17.0.0-rc2 into a f39 side-tag in Koji.
6. Push F39 Bodhi Update with 17.0.0-rc2 (or 17.0.0-rc1 if -rc2 is not ready) prior to the Beta Freeze.
7. Continue building new release candidates and pushing them to stable until the Final Freeze.

Updates after 17.0.0-rc2 will generally be very small and can be done after the Final Freeze is over. If we are late packaging -rc3 or the final release, we will not ask for a Final Freeze exception, unless they contain a fix for a critical release blocking bug.

Benefit to Fedora

New features and bug fixes provided by the latest version of LLVM.

Scope

• Proposal owners:
  • Review existing llvm and clang compatibility packages and orphan any packages that are no longer used.
  • Do scratch builds of Fedora packages that depend on llvm and report issues to package maintainer.

• Other developers:
  • Fix build issues found with LLVM-17 or switch their package to use the llvm16 compat libs.

• Release engineering: [1]

• Policies and guidelines: N/A (not needed for this Change)

• Trademark approval: N/A (not needed for this Change)

• Alignment with Community Initiatives:

Upgrade/compatibility impact

This change should not impact upgradeability.

How To Test

The CI tests for the llvm sub-packages in Fedora will be used to catch regressions that might be potentially introduced by the update to LLVM 17.

Dependencies

Packages that depend on one of the llvm packages will need to be updated to work with LLVM17 or will need to switch to using one of the llvm16 compat packages.

Contingency Plan

• Contingency mechanism: If there are major problems with LLVM 17, the compatibility package provide a way for other packages to continue using LLVM 16.
• Contingency deadline: Beta Freeze
• Blocks release? No

Documentation

Release notes will be added for this change.