Fedora 32 System-Wide Change proposal: Stop shipping individual component libraries in clang-libs package
https://fedoraproject.org/wiki/Changes/Stop-Shipping-Individual-Component...
== Summary ==
Remove the individual component libraries (e.g. libclangBasic.so,
libclangAST.so, etc.) from the clang-libs package. Packages that
depend on the clang libraries should instead link against
libclang-cpp.so.
== Owner ==
* Name: [[User:tstellar| Tom Stellard]]
* Email: <tstellar(a)redhat.com>
== Detailed Description ==
The individual component libraries will be removed from the clang-libs
package in favor of libclang-cpp.so (which is already present in
clang-libs). The component shared libraries enabled by the
BUILD_SHARED=ON CMake option are not supported as a distribution
configuration by the upstream project and only recommended for use by
clang developers.[1]
The libclang-cpp.so shared object was added in clang 9.0 and now gives
us an alternative shared library option that is supported by the
upstream project and makes it possible for Fedora packages to stop
using the component libraries.
[1] https://llvm.org/docs/CMake.html
== Benefit to Fedora ==
We will improve stability in Fedora by packaging a build configuration
that is supported by the upstream project. In addition,
libclang-cpp.so will provide more LTO optimization opportunities than
the component libraries if LTO is enabled in Fedora builds. Also, in
order to access the clang API with the component libraries, an
application might need to link with up to 37 different shared
libraries, replacing these with a single shared library will help
improve application start-up times.
== Scope ==
* Proposal owners:
** The proposal owner will ensure that that all packages that depend
on clang-libs are updated to use libclang-cpp.so.
** Once all dependent packages have been migrated, the clang package
will be updated to pass -DBUILD_SHARED=OFF to cmake when configuring.
* Other developers: The other maintainers will be responsible for
reviewing and approving changes to their packages.
* Release engineering: [https://pagure.io/releng/issues/9096]
* Policies and guidelines: No policies or guidelines will need to be
updated as a result of this change.
* Trademark approval: N/A (not needed for this Change)
== Upgrade/compatibility impact ==
This change should not impact upgradeability.
== How To Test ==
This can be tested using existing CI tests or tests in the %check
section of spec files. The changes should not be visible to end users
so tests should behave exactly as they did before the change.
== User Experience ==
End users that develop applications using the clang libraries will
need to update their applications to use libclang-cpp.so instead of
the individual component libraries if they want to use libraries
shipped with Fedora. This may be inconvenient, but we don't want
users to continue using a configuration that is not supported by the
upstream project. Once this change is made though, the applications
will see the same benefits mentioned in the "Benefits to Fedora"
section.
End users using Fedora packages that depend on clang libraries will
not need to do anything different.
== Dependencies ==
The following packages depend on clang-libs and will need to be updated:
* bcc
* bpftrace
* castxml
* ccls
* clazy
* gnome-builder
* ispc
* kdevelop
* lldb
* mesa
* pocl
* qt-creator
* qt5-doctools
* shiboken2
* tinygo
== Contingency Plan ==
* Contingency mechanism: (What to do? Who will do it?) If we are
unable to migrate all dependent packages in time, then the proposal
owner will postpone the final step of passing -DBUILD_SHARED_LIBS=OFF
to cmake when configuring clang until a future Fedora release. In this
case, packages that have already been migrated will continue to work,
since libclang-cpp.so is already included in the clang-libs package.
* Contingency deadline: Change Checkpoint: Completion deadline
* Blocks release? No
* Blocks product? None
== Documentation ==
Release notes will be added for this change.
== Release Notes ==
The individual component libraries (e.g. libclangBasic.so,
libclangAST.so, etc.) have been removed from the clang-libs packages.
Developers who want to link their application against the clang
libraries should link against libclang-cpp.so instead.
--
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis