Fedora 31 System-Wide Change proposal: Boost 1.70 upgrade

[Ben Cotton]

https://fedoraproject.org/wiki/Changes/F31Boost170

== Summary ==
This change brings Boost 1.70 to Fedora. This will mean Fedora ships
with a recent upstream Boost release.

== Owner ==

* Name: [[User:jwakely| Jonathan Wakely]]
* Email: [e-mail]

== 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
[[Changes/F30Boost169|Fedora 30 Change]], [[Changes/F29Boost167|Fedora
29 Change]], [[Changes/F28Boost166|Fedora 28 Change]],
[[Changes/F27Boost164|Fedora 27 Change]], [[Changes/F26Boost163|Fedora
26 Change]], [[Changes/F25Boost161|Fedora 25 Change]],
[[Changes/F24Boost160|Fedora 24 Change]],
[[Changes/F23Boost159|Fedora 23 Change]] and
[[Changes/F22Boost158|Fedora 22 Change]].

== Benefit to Fedora ==

Fedora 30 includes Boost 1.69, but the latest upstream release, Boost
1.70, was released on April 12th, 2019.

Fedora will stay relevant, as far as Boost clients are concerned.
Boost 1.70 brings two new components:
* [https://www.boost.org/libs/outcome/ Boost.Outcome], A set of tools
for reporting and handling function failures in contexts where
<i>directly</i> using C++ exception handling is unsuitable, from Niall
Douglas.
* [https://www.boost.org/libs/histogram/ Boost.Histogram], Fast and
extensible multi-dimensional histograms with convenient interface for
C++14, from Hans Dembinski.

== Scope ==
* Proposal owners:
** Build will be done with Boost.Build v2 (which is the
upstream-sanctioned way of building Boost)
** Request a "f31-boost"
[https://docs.pagure.org/releng/sop_adding_side_build_targets.html
build system tag]
([http://lists.fedoraproject.org/pipermail/devel/2011-November/159908.html
discussion]): https://pagure.io/releng/issue/8061
** 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/8500] (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 ==
* No impact on system upgrade (no removed subpackages this time).
* No manual configuration or data migration needed.
* Some impact on other packages needing code changes to rebuild.
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>$ dnf repoquery -s --releasever=rawhide --whatrequires
libboost* --disablerepo=* --enablerepo=fedora | sort -u</code>

All clients:
<code>$ dnf 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 F31 with Boost 1.69, 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 July 2019,
ideally before the mass rebuild.

* Blocks release? No
* Blocks product? None

== Documentation ==
* 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 1.70. Apart from a number of bug
fixes and improvements to existing libraries, compared to Fedora 30,
this brings:
* New header-only components: [https://www.boost.org/libs/outcome/
Boost.Outcome] and [https://www.boost.org/libs/histogram/
Boost.Histogram]

[Ben Cotton]

On Tue, Jul 2, 2019 at 10:02 AM Ben Cotton  wrote:
> https://fedoraproject.org/wiki/Changes/F31Boost170
>
> == Summary ==
> This change brings Boost 1.70 to Fedora. This will mean Fedora ships
> with a recent upstream Boost release.

This change, previously approved by FESCo, has been withdrawn by the
change owner.