Changes/F33Boost173

Boost 1.73 upgrade

Summary

This change brings Boost 1.73 to Fedora. This will mean Fedora ships with a recent upstream Boost release.

Owner

• Name: Jonathan Wakely
• Email: jwakely@redhat.com

Current status

• Targeted release: Fedora 33
• Last updated: 2020-04-27
• 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

The aim is to synchronize Fedora with the most recent Boost release. Because ABI stability is one of explicit Boost non-goals, this entails rebuilding of all dependent packages. This has also always entailed yours truly assisting maintainers of client packages in decoding cryptic boost-ese seen in output from g++. Such care is to be expected this time around as well.

The equivalent changes for previous releases were Fedora 30 Change, Fedora 29 Change, Fedora 28 Change, Fedora 27 Change, Fedora 26 Change, Fedora 25 Change, Fedora 24 Change, Fedora 23 Change and Fedora 22 Change.

Benefit to Fedora

Fedora 32 includes Boost 1.69 which is the same version as F31 and F30, and is several releases behind the latest upstream release (Boost 1.73 is due for release late April 2020).

Fedora will stay relevant, as far as Boost clients are concerned. Boost 1.73 brings four new components:

• Boost.Outcome, A set of tools for reporting and handling function failures in contexts where directly using C++ exception handling is unsuitable, from Niall Douglas.
• Boost.Histogram, Fast and extensible multi-dimensional histograms with convenient interface for C++14, from Hans Dembinski.
• Boost.Variant2, A never-valueless, strong guarantee implementation of std::variant, from Peter Dimov.
• Boost.Nowide, Standard library functions with UTF-8 API on Windows, from Artyom Beilis.

Scope

• Proposal owners:
  • Build will be done with Boost.Build v2 (which is the upstream-sanctioned way of building Boost)
  • Request a "f33-boost" build system tag (discussion): TODO
  • Build boost into that tag (take a look at the build #606493 for inspiration)
  • Post a request for rebuilds to fedora-devel
  • Work on rebuilding dependent packages in the tag.
  • When most is done, re-tag all the packages to rawhide
  • Watch fedora-devel and assist in rebuilding broken Boost clients (by fixing the client, or Boost).

• Other developers:
  • Those who depend on Boost DSOs will have to rebuild their packages. Feature owners will alleviate some of this work as indicated above, and will assist those whose packages fail to build in debugging them.
  • The existing boost-nowide package will need to be retired, as it is now included in the upstream Boost release.

• Release engineering: #9421 (a check of an impact with Release Engineering is needed)

• Policies and guidelines:
  • Apart from scope, this is business as usual, so no new policies, no new guidelines.

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

Upgrade/compatibility impact

• The boost-jam package has been replaced by boost-b2. The separate boost-nowide package will be replace by a subpackage of boost.
• No manual configuration or data migration needed.
• Some impact on other packages needing code changes to rebuild. Historically this hasn't been too much of a problem and could always be resolved before deadline.

How To Test

• No special hardware is needed.
• Integration testing simply consists of installing Boost packages (dnf install boost) on Fedora and checking that it does not break other packages (see below for a way to obtain a list of boost clients).

User Experience

• Expected to remain largely the same.
• Developers building third-party software on Fedora may need to rebuild against the new Boost packages, and may need to adjust their code if the new Boost release is not source-compatible.
• Developers using bjam to build their own software will need to switch to using the new name for the tool, b2

Dependencies

Packages that must be rebuilt: $ dnf repoquery -s --releasever=rawhide --whatrequires libboost\* --disablerepo=* --enablerepo=fedora | sort -u

All clients: $ dnf repoquery --releasever=rawhide --archlist=src --whatrequires boost-devel --disablerepo='*' --enablerepo=fedora-source

Contingency Plan

• Contingency mechanism: Worst case scenario is to abandon the update and simply ship F33 with Boost 1.69, which is already in rawhide. It would also be possible to ship an older release (1.70.0, 1.71.0 or 1.72.0) which would still be newer than in current Fedora releases.

• Contingency deadline: We will know whether the change can be made once the rebuilds in the side tag are done, which will be July 2020, ideally before the mass rebuild.

• Blocks release? No
• Blocks product? None

Documentation

• https://www.boost.org/users/history/version_1_73_0.html (Beta1 released on 12 April 2020, final release expected soon)
• https://www.boost.org/users/history/version_1_72_0.html (released on 11 December 2019)
• https://www.boost.org/users/history/version_1_71_0.html (released on 19 August 2019)
• https://www.boost.org/users/history/version_1_70_0.html (released on 12 April 2019)
• https://www.boost.org/development/index.html

Release Notes

Boost has been upgraded to version 1.73. Apart from a number of bug fixes and improvements to existing libraries. Compared to Fedora 32, this brings:

• New header-only components: Boost.Outcome, Boost.Histogram, Boost.Variant2 and Boost.Nowide.
• The bjam tool in the boost-jam package has been replaced by b2 in the boost-b2 package.