Revision as of 17:42, 20 December 2021

LLVM 14

Summary

Update all llvm sub-projects in Fedora Linux to version 14.

Owner

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

Current status

Targeted release: Fedora Linux 36
Last updated: 2021-12-20
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 14, and there will be a soname version change for the llvm libraries. Compatibility packages clang13 and llvm13 will be added to ensure that packages that currently depend on clang and llvm version 13 libraries will continue to work.

Unlike previous releases, we will no longer be packaging release candidate builds in Rawhide or F36. Release candidates are not guaranteed to be ABI compatible with each other, so upgrading from one release candidate to another (or to the final release) requires rebuilding all the clang/LLVM library users. This has become very difficult to coordinate given the increased number of packages using the clang/LLVM libraries, so we decided to only package the final release.

We do plan to build release candidate versions into a side-tag for testing. We will also create an llvm-14 branch in dist-git, so that we can build the release candidate versions while still being able to fix bugs and make changes to LLVM 13 in the rawhide branch.

Note: we are still discussing with Release Engineering if a branch + side-tag will be possible #10414. If it's not possible, we will use COPR instead.

Feedback

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.
- Request an llvm-14 branch in dist-git for each llvm sub-project.
- Request a side-tag.
- Build llvm13 and clang13 compat packages into the side-tag.
- When upstream LLVM project releases version 14.0.0-rc1 (Late January 2021), package this using the llvm-14 branches and build it into the side-tag.
  - Repeat process for each release candidate.
- When upstream LLVM project releases version 14.0.0-final (March 2021), package this using the rawhide and f36 branches.

Other developers:
- Maintainers of packages that depend on clang-libs or llvm-libs will need to update their spec files to depend on the clang13 and llvm13 compatibility packages if they want to rebuild their package and it does not work with LLVM 14 yet. The key point here is that spec file changes are only needed if a package is going to be rebuilt after LLVM 14 is added to Fedora. The compatibility packages will ensure that already built packages continue to work.

Release engineering: #10414

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

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

Alignment with Objectives:

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 14.

User Experience

Users will benefit from new features and bug-fixes in the latest version of LLVM.

Dependencies

This change can be made without updating any other packages. However, as mention before, packages that need to use LLVM 13 will need to update their spec file on their first rebuild after this change.

Contingency Plan

Contingency mechanism: (What to do? Who will do it?): If there are major problems with LLVM 14, the compatibility package provide a way for other packages to continue using LLVM 13.

Contingency deadline: Final Freeze
Blocks release? No

Documentation

Release notes will be added for this change.

Release Notes

LLVM sub-projects in Fedora have been updated to version 14:

llvm
clang
lld
lldb
compiler-rt
libomp
llvm-test-suite
libcxx
libcxxabi
python-lit
flang
mlir
polly
libclc
llvm-unwind

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+* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/W7KG4VKBUL5IIOYPSWNTSGKWSSII253T/ devel thread]
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 * Tracker bug: <will be assigned by the Wrangler>
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-* Contingency mechanism: (What to do?  Who will do it?): If there are major problems with LLVM 13, the compatibility package provide a way for other packages to continue using LLVM 12.
+* Contingency mechanism: (What to do?  Who will do it?): If there are major problems with LLVM 14, the compatibility package provide a way for other packages to continue using LLVM 13.
 <!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->

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