F41 Change Proposal: GNUToolchain (system-wide)

[Aoife Moloney]

Wiki - https://fedoraproject.org/wiki/Changes/GNUToolchainF41

This document represents a proposed Change. As part of the Changes
process, proposals are publicly announced in order to receive
community feedback. This proposal will only be implemented if approved
by the Fedora Engineering Steering Committee.

== Summary ==
Update the Fedora 41 GNU Toolchain to gcc 14.1+, binutils 2.42+, glibc
2.40 and gdb 14+.

The set of core GNU Toolchain packages for Fedora 41 are as follows:

* GNU C Compiler 14.1+
** Associated runtimes for C++ (libstdc++), Go (gccgo), OpenMP (gomp),
Fortran (gfortran), D (phobos), Objective C/C++.
* GNU Binary Utilities 2.42+
* GNU C Library 2.40
* GNU Debugger 14+ (immediately available in Fedora 40)

The gcc 14.1+ change will be tracked in this top-level GNU Toolchain
system-wide update.

The binutils 2.42+ change will be tracked in this top-level GNU
Toolchain system-wide update.

The glibc 2.40 change will be tracked in this top-level GNU Toolchain
system-wide update.

The gdb 14+ update was rolled out across all Fedora releases and the
move to 14+ will be handled in the same fashion. The debugger is
capable of debugging the binary artifacts produced by the rest of the
system toolchain.

== Owner ==
* Name: [[User:codonell|Carlos O'Donell]]

* Email: carlos(a)redhat.com


== Detailed Description ==
The GNU Compiler Collection, GNU Binary Utilities, GNU C Library, and
the GNU Debugger make up the core part of the GNU Toolchain and it is
useful for our users to transition these components as a complete
implementation when making a new release of Fedora.

<!-- Use this text for a GCC update: -->
The GNU Compiler Collection is expected to release version 14.1+
(point release), before the Fedora 41 release. It will contain many
new features, documented here:
https://gcc.gnu.org/gcc-14/changes.html. The latest point release for
gcc 14.1+ will be included in Fedora 41, this will most probably be
14.2 or later.

<!-- Use this text for a BINUTILS update: -->
The GNU Binutils version 2.42 was released before Fedora 41; and we
have already been using this version of binutils in Fedora Rawhide
successfully to build the distribution. Given the present schedule for
Fedora 41 we will continue to use Binutils 2.42 or 2.43 if deemed
stable enough.  As an experiment we will be trying out more frequent
updates to the rawhide binutils, so that it remains closer to the
upstream master sources.  Currently rawhide binutils is synced twice a
year, bu the plan is to try syncing monthly or maybe every fortnight.

<!-- Use this text for a GLIBC update: -->
The GNU C Library version 2.40 is expected to be release before Fedora
41; we have started closely tracking the glibc 2.40 development code
in Fedora Rawhide and are addressing any issues as they arise. Given
the present schedule Fedora 41 will branch after the release of glibc
2.40. However, the mass rebuild schedule means Fedora 41 will mass
rebuild (if required) before the final release of glibc 2.40, but
after the ABI is frozen.

<!-- Use this text for a GDB update: -->
The GNU Debugger version 14+ has already been rolled out across all
Fedora releases at the same time.

== Benefit to Fedora ==
Stays up to date with latest features, improvements, security and bug
fixes from gcc, glibc, binutils, and gdb upstream.

The goal is to track and transition to the latest components of the
GNU Toolchain.

== Scope ==
* Proposal owners: Fedora Toolchain Team (gcc, glibc, binutils, gdb,
...) developers need to ensure that gcc, glibc, binutils, and gdb in
rawhide are stable and ready for the Fedora 41 branch. <!-- What work
do the feature owners have to accomplish to complete the feature in
time for release?  Is it a large change affecting many parts of the
distribution or is it a very isolated change? What are those
changes?-->

* Other developers: Given that glibc is backwards compatible and we
have been testing the new glibc in rawhide it should make very little
impact when updated, except for the occasional deprecation warnings
and removal of legacy interfaces from public header files

* Release engineering: A mass rebuild is strongly encouraged;
[https://pagure.io/releng/issue/11898 #11898]

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

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

* Alignment with Objectives: N/A



== Upgrade/compatibility impact ==
The compiler, the static linker and the the library are backwards
compatible with the previous version of Fedora.

<!-- Use this text for a GCC X update: We want to call out the CHANGES
URL from upstream. -->
<!-- Some source changes may be required for gcc X rebase:
https://gcc.gnu.org/gcc-X/changes.html -->

Any source level changes required for glibc 2.40 will be noted here:
https://sourceware.org/glibc/wiki/Release/2.40#Packaging_Changes

== How To Test ==
<!-- Use this text for a GCC update: -->
The GNU Compiler Collection has its own test suite which is run during
the package build and examined by the gcc developers before being
uploaded.

<!-- Use this text for a GLIBC update: -->
The GNU C Library has its own test suite which is run during the
package build and examined by the glibc developers before being
uploaded. This test suite has over 6200 tests that run to verify the
correct operation of the library. In the future we may also run the
microbenchmark to look for performance regressions.

<!-- Use this text for a BINUTILS update: -->
The GNU Binutils has its own test suite which is run during the
package build and examined by binutils developers before being
uploaded. The regression test suite is run to verify the correct
operation of the static linker and attendant utilities.

<!-- Use this text for a GDB update: -->
The GNU Debugger has its own test suite which is run during the
package build and examined by gdb developers before being uploaded.
The regression test suite is run to verify the correct operation of
the debugger.

== User Experience ==
<!-- TODO: Talk about any new GNU Toolchain user experience updates. -->
Upgrading the 4 main GNU Toolchain components (gcc, binutils, glibc,
and gdb) ensures that users have an up to date working system
compiler, assembler, static linker, core language runtimes (C, C++,
etc), dyanmic linker, and debugger. All of these components are being
updated to provide support for newer language features, and hardware
features; enabling users to make use of these features for their
applications. In some cases the components are updated in a
synchronized fashion if a feature requires support across the
components that constitute the implementation e.g. compiler feature
that requires language library support.

== Dependencies ==
All packages do not need to be rebuilt due to backwards compatibility.
However, it is advantageous if a mass rebuild is performed during the
Fedora 41 cycle. The mass rebuild would ensure all packages can be
built with the newer compiler and core runtime.

== Contingency Plan ==
* Contingency mechanism glibc: If glibc 2.40 proves too disruptive to
compiling the distribution we could revert to 2.39, but given that
Rawhide has started tracking glibc 2.40, no show-stopper problems are
expected.  At this point we can still revert to upstream version 2.39
if insurmountable problems appear, but to do so may require a mass
rebuild to remove new symbols from the ABI/API.

* Contingency mechanism binutils: If binutils 2.42 proves too
distruptive to assembling and linking the distribution we could revert
to 2.41, but given that Rawhide is using 2.42, no show-stopper
problems are expected. At this point we can still revert if
insurmountable problems appear, but to do so may require a mass
rebuild if the defects involve generated binaries.

<!-- Use this text for a GCC update: -->
<!-- Not needed in F[X is odd] because GCC is not being updated. -->
* Contingency mechanism for gcc: If gcc 14.1+ proves too disruptive to
compiling the distribution we could revert to gcc 14.0.

<!-- No comments needed because GDB updates asynchornously. -->

* Contingency deadline: Fedora mass rebuild on 2024-07-17.

* Blocks release?
** No, upgrading to gcc 14+ does block the release.
** Yes, upgrading to binutils 2.42 does block the release.
** Yes, upgrading to glibc 2.40 does block the release.
** No, upgrading to gdb 14+ does not block the release.



== Documentation ==
The gcc manual contains the documentation for the release and doesn't
need any more additional work.

The binutils manual contains the documentation for the release and
doesn't need any more additional work.

The glibc manual contains the documentation for the release and
doesn't need any more additional work.

The gdb manual contains the documentation for the release and doesn't
need any more additional work.


== Release Notes ==
<!-- Use this text for GCC updates: -->

See https://gcc.gnu.org/gcc-14/changes.html for the GNU Compiler
Collection version 14 release notes.

<!-- Use this text for GLIBC updates: -->
The GNU C Library version 2.40 will be released at the beginning of
August 2024. The current NEWS notes can be seen here as they are
added: https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS;hb=HEAD

The GNU Binary Utilities version 2.42 was released February 2024. The
current release notes will be sent to the developer mailing list.




-- 

Aoife Moloney

Fedora Operations Architect

Fedora Project

Matrix: @amoloney:fedora.im

IRC: amoloney