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Fedora 30 System-Wide Change Proposal: Boost 1.69 Upgrade

<a href="https://fedoraproject.org/wiki/Changes/F30Boost169" title="https://fedoraproject.org/wiki/Changes/F30Boost169">https://fedoraproject.org/wiki/Changes/F30Boost169</a>

== Summary ==
This change brings Boost 1.69 to Fedora. This will mean Fedora ships
with a recent upstream Boost release.

== Owner ==
* Name: [[User:jwakely|Jonathan Wakely]]
* Email: jwakely at fedoraproject dot org

== 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.

== Benefit to Fedora ==
Fedora 29 includes Boost 1.67 but the latest upstream release, Boost
1.68, was released on August 9th, 2018 (the 1.69 release is scheduled
for mid-November 2018, so it should be in time for F30).

Fedora will stay relevant, as far as Boost clients are concerned.
Boost 1.68 brings two new libraries:
* [https://www.boost.org/doc/libs/1_68_0/doc/html/yap.html YAP], an
expression template library for C++14 and later, from Zach Laine.

== Scope ==
* Proposal owners:
** Build will be done with Boost.Build v2 (which is the
upstream-sanctioned way of building Boost)
** Request a "f30-boost" build system tag
([http://lists.fedoraproject.org/pipermail/devel/2011-November/159908.html
discussion]): <a href="https://pagure.io/releng/issue/7614" title="https://pagure.io/releng/issue/7614">https://pagure.io/releng/issue/7614</a>
** Build boost into that tag (take a look at the
[http://koji.fedoraproject.org/koji/buildinfo?buildID=606493 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.

* Release engineering: [https://pagure.io/releng/issue/7595] (a check
of an impact with Release Engineering is needed)
** [[Fedora_Program_Management/ReleaseBlocking/Fedora{{FedoraVersionNumber|next}}|List
of deliverables]]: All deliverables will include updated Boost
packages.

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

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

== Upgrade/compatibility impact ==
* No impact on system upgrade.
* No manual configuration or data migration needed.
* Some impact on other packages. Historically this hasn't been too big
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
(<code>dnf install boost</code>) 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.

== Dependencies ==
Packages that must be rebuilt:
<code>$ repoquery -s --releasever=rawhide --whatrequires libboost\*
--disablerepo=* --enablerepo=fedora | sort -u</code>

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

== Contingency Plan ==
* Contingency mechanism: Worst case scenario is to abandon the update
and simply ship F30 with Boost 1.67, which is already in rawhide.

* Contingency deadline: We will know whether the change can be made
once the rebuilds in the side tag are done, which will be January
2019, ideally before the mass rebuild.

* Blocks release? No
* Blocks product? None

== Documentation ==
* <a href="https://www.boost.org/users/history/version_1_68_0.html" title="https://www.boost.org/users/history/version_1_68_0.html">https://www.boost.org/users/history/version_1_68_0.html</a>
* <a href="https://www.boost.org/development/index.html" title="https://www.boost.org/development/index.html">https://www.boost.org/development/index.html</a>