Latest revision as of 13:56, 16 February 2022

GNU Toolchain Update (gcc 12, glibc 2.35)

Summary

Update the Fedora 36 GNU Toolchain to gcc 12 and glibc 2.35.

The gcc 12 is currently under development and will be included in Fedora 36 upon release. The glibc 2.35 change will be tracked in this top-level GNU Toolchain system-wide update.

Owner

Name: Arjun Shankar
Email: arjun@redhat.com

Current status

Targeted release: Fedora Linux 36
Last updated: 2022-02-16
devel thread
FESCo issue: #2750
Tracker bug: #2050761
Release notes tracker: #805

Detailed Description

The GNU Compiler Collection, GNU C Library, GNU Debugger, and GNU Binary Utilities 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.

The GNU Compiler Collection is expected to release version 12 in Q2, before the Fedora 36 release. It will contain many new features, documented here: https://gcc.gnu.org/gcc-12/changes.html. The latest point release for gcc 12 will be included in Fedora 36, this will most probably be 12.1.

The GNU C Library version 2.35 is expected to be released in the beginning of February 2022; we have started closely tracking the glibc 2.35 development code in Fedora Rawhide and are addressing any issues as they arise. Given the present schedule Fedora 36 will branch after the release of glibc 2.35. However, the mass rebuild schedule means Fedora 36 will mass rebuild (if required) before the final release of glibc 2.35, but after the ABI is frozen.

The GNU Binutils version 2.37 and GNU Debugger version 11.1 currently included in Fedora 35 will continue to be included in Fedora 36. There will be a GNU Binutils version 2.38 released at the end of January, but the inclusion will be scheduled for Fedora 37.

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 36 branch.

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. An update to GCC 12.1 would mean a new major release and could have broad scope for change.

Release engineering: A mass rebuild is strongly encouraged; #10515

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.

The upgrade to glibc-2.35 coincides with the removal of nscd.

Some source changes may be required for gcc 12 rebase: https://gcc.gnu.org/gcc-12/changes.html

How To Test

The GNU Compiler Collection has its own testsuite which is run during the package build and examined by the gcc developers before being uploaded.

The GNU C Library has its own testsuite, 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.

User Experience

Users will see improved performance, many bugfixes and improvements to POSIX compliance, Unicode 14 support, C.UTF-8 locale support, improved experimental support for C++20 and C++23, new compiler warnings and improvements to existing ones, and more.

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 36 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 2.35 proves too disruptive to compiling the distribution we could revert to 2.34, but given that Rawhide has started tracking glibc 2.35, no show-stopper problems are expected. At this point, we can still revert to upstream version 2.34 if insurmountable problems appear, but to do so may require a mass rebuild to remove new symbols from the ABI/API.
Contingency mechanism for gcc: If gcc 12 proves too disruptive to compiling the distribution we could revert to gcc 11.

Contingency deadline: Fedora mass rebuild on 2022-01-19.
Blocks release? Yes, upgrading to the gcc 12 release blocks the release. Yes, upgrading to glibc 2.35 does block the release.

Documentation

The gcc 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.

Release Notes

The GNU Compiler Collection version 12 is soon to be released. See https://gcc.gnu.org/gcc-12/changes.html.

The GNU C Library version 2.35 will be released at the beginning of August 2021. 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

@@ Line 1: / Line 1: @@
-{{admon/important | Comments and Explanations | The page source contains comments providing guidance to fill out each section. They are invisible when viewing this page. To read it, choose the "view source" link.<br/> '''Copy the source to a ''new page'' before making changes!  DO NOT EDIT THIS TEMPLATE FOR YOUR CHANGE PROPOSAL.'''}}
+<!-- The actual name of your proposed change page should look something like: Changes/Your_Change_Proposal_Name.  This keeps all change proposals in the same namespace -->
-{{admon/tip | Guidance | For details on how to fill out this form, see the [https://docs.fedoraproject.org/en-US/program_management/changes_guide/ documentation].}}
+= GNU Toolchain Update (gcc 12, glibc 2.35) <!-- The name of your change proposal --> =
-<!-- The actual name of your proposed change page should look something like: Changes/Your_Change_Proposal_Name.  This keeps all change proposals in the same namespace -->
-= GNU Toolchain Update (gcc 12, glibc 2.35, binutils 2.38, gdb 11.1) <!-- The name of your change proposal --> =
 == Summary ==
 <!-- A sentence or two summarizing what this change is and what it will do. This information is used for the overall changeset summary page for each release. Note that motivation for the change should be in the Benefit to Fedora section below, and this part should answer the question "What?" rather than "Why?". -->
-Switch the Fedora 36 GNU Toolchain to gcc 12 (latest point release), binutils 2.38, glibc 2.35, and gdb 11.1.
+Update the Fedora 36 GNU Toolchain to gcc 12 and glibc 2.35.
+The gcc 12 is currently under development and will be included in Fedora 36 upon release. The glibc 2.35 change will be tracked in this top-level GNU Toolchain system-wide update.
-The gcc 12 is currently under development and will be included in Fedora 36 upon release. The glibc 2.35 change will be tracked in this top-level GNU Toolchain system-wide update. Likewise the binutils 2.38 release will be tracked in this top-level GNU Toolchain system-wide update. The gdb 11.1 is already in Fedora 36, but the release will be updated to the latest point release.
 == Owner ==
@@ Line 28: / Line 26: @@
 == Current status ==
-[[Category:ChangePageIncomplete]]
+[[Category:ChangeAcceptedF36]]
 <!-- When your change proposal page is completed and ready for review and announcement -->
 <!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
@@ Line 46: / Line 44: @@
 ON_QA -> change is fully code complete
 -->
-* FESCo issue: <will be assigned by the Wrangler>
+* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/AZD3XBK54M5FU6RI65NSUSDQ4CNEHEAH/ devel thread]
-* Tracker bug: <will be assigned by the Wrangler>
+* FESCo issue: [https://pagure.io/fesco/issue/2750 #2750]
-* Release notes tracker: <will be assigned by the Wrangler>
+* Tracker bug: [https://bugzilla.redhat.com/show_bug.cgi?id=2050761 #2050761]
+* Release notes tracker: [https://pagure.io/fedora-docs/release-notes/issue/805 #805]
 == Detailed Description ==
 <!-- Expand on the summary, if appropriate.  A couple sentences suffices to explain the goal, but the more details you can provide the better. -->
-The GNU Compiler Collection, GNU C Library, GNU Debugger, and GNU Binary Utilities make up the core part of the GNU Toolchain and it is useful to transition these components as a complete implementation when making a new release of Fedora.
+The GNU Compiler Collection, GNU C Library, GNU Debugger, and GNU Binary Utilities 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.
-The GNU Compiler Collection is expected to release version 12 containing many new features documented here: https://gcc.gnu.org/gcc-12/changes.html. The latest point release for gcc 12 will be included in Fedora 36, this will most probably mean 12.1, or possibly 12.2.
+The GNU Compiler Collection is expected to release version 12 in Q2, before the Fedora 36 release. It will contain many new features, documented here: https://gcc.gnu.org/gcc-12/changes.html. The latest point release for gcc 12 will be included in Fedora 36, this will most probably be 12.1.
-The GNU C Library version 2.35 is expected to be released in the beginning of February 2022; we have started closely tracking the glibc 2.35 development code in Fedora Rawhide and are addressing any issues as they arise. Given the present schedule Fedora 36 will branch after the release of glibc 2.35. However, the mass rebuild schedule means Fedora 36 will mass rebuild (if required).
+The GNU C Library version 2.35 is expected to be released in the beginning of February 2022; we have started closely tracking the glibc 2.35 development code in Fedora Rawhide and are addressing any issues as they arise. Given the present schedule Fedora 36 will branch after the release of glibc 2.35. However, the mass rebuild schedule means Fedora 36 will mass rebuild (if required) before the final release of glibc 2.35, but after the ABI is frozen.
-The GNU Binutils version 2.38 will be released near the end of TODO INCLUDE MONTH 2022;
+The GNU Binutils version 2.37 and GNU Debugger version 11.1 currently included in Fedora 35 will continue to be included in Fedora 36. There will be a GNU Binutils version 2.38 released at the end of January, but the inclusion will be scheduled for Fedora 37.
-The GNU Debugger verion 11.1 is already released.
 == Benefit to Fedora ==
@@ Line 92: / Line 89: @@
 -->
-Stays up to date with latest features, improvements security and bug fixes from gcc, binutils, gdb and glibc upstream.
+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, ...)
+* 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 36 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?-->
-<!-- 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: Developers need to ensure that gcc, binutils, gdb, and glibc in rawhide are stable and ready for the Fedora 36 branch. 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.  An update to GCC 12.1 would be mean a new major release and could have broad scope for change. The binutils 2.38 update also has the broad scope for change and generated object files should be reviewed and failures to build analyzed.
+* 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.  An update to GCC 12.1 would mean a new major release and could have broad scope for change. <!-- What work do other developers 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?-->
-<!-- What work do other developers 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?-->
-* Release engineering: [https://pagure.io/releng/issues #Releng issue number] <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Release engineering: A mass rebuild is strongly encouraged; [https://pagure.io/releng/issue/10515 #10515]
 <!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)?  Is a mass rebuild required?  include a link to the releng issue.
 The issue is required to be filed prior to feature submission, to ensure that someone is on board to do any process development work and testing and that all changes make it into the pipeline; a bullet point in a change is not sufficient communication -->
-A mass rebuild is strongly encouraged. TODO LIST ANY SPECIFICS TO LOOK OUT FOR.
 * Policies and guidelines: N/A (not needed for this Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
@@ Line 115: / Line 109: @@
 <!-- If your Change may require trademark approval (for example, if it is a new Spin), file a ticket ( https://pagure.io/Fedora-Council/tickets/issues ) requesting trademark approval from the Fedora Council. This approval will be done via the Council's consensus-based process. -->
-* Alignment with Objectives:
+* Alignment with Objectives: N/A
 <!-- Does your proposal align with the current Fedora Objectives: https://docs.fedoraproject.org/en-US/project/objectives/ ? It's okay if it doesn't, but it's something to consider -->
 == Upgrade/compatibility impact ==
 <!-- What happens to systems that have had a previous versions of Fedora installed and are updated to the version containing this change? Will anything require manual configuration or data migration? Will any existing functionality be no longer supported? -->
+The compiler, the static linker and the the library are backwards compatible with the previous version of Fedora.
+The upgrade to glibc-2.35 coincides with the [[Changes/RemoveNSCD|removal of nscd]].
+Some source changes may be required for gcc 12 rebase: https://gcc.gnu.org/gcc-12/changes.html
 <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
@@ Line 139: / Line 138: @@
 -->
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+The GNU Compiler Collection has its own testsuite which is run during the package build and examined by the gcc developers before being uploaded.
+The GNU C Library has its own testsuite, 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.
@@ Line 153: / Line 154: @@
   - Green has been scientifically proven to be the most relaxing color. The move to a default background color of green with green text will result in Fedora users being the most relaxed users of any operating system.
 -->
+Users will see improved performance, many bugfixes and improvements to POSIX compliance, Unicode 14 support, C.UTF-8 locale support, improved experimental support for C++20 and C++23, new compiler warnings and improvements to existing ones, and more.
 == Dependencies ==
 <!-- What other packages (RPMs) depend on this package?  Are there changes outside the developers' control on which completion of this change depends?  In other words, completion of another change owned by someone else and might cause you to not be able to finish on time or that you would need to coordinate?  Other upstream projects like the kernel (if this is not a kernel change)? -->
+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 36 cycle. The mass rebuild would ensure all packages can be built with the newer compiler and core runtime.
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
@@ Line 163: / Line 165: @@
 <!-- If you cannot complete your feature by the final development freeze, what is the backup plan?  This might be as simple as "Revert the shipped configuration".  Or it might not (e.g. rebuilding a number of dependent packages).  If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy.  -->
-* Contingency mechanism: (What to do?  Who will do it?) N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Contingency mechanism glibc: If glibc 2.35 proves too disruptive to compiling the distribution we could revert to 2.34, but given that Rawhide has started tracking glibc 2.35, no show-stopper problems are expected.  At this point, we can still revert to upstream version 2.34 if insurmountable problems appear, but to do so may require a mass rebuild to remove new symbols from the ABI/API.
+* Contingency mechanism for gcc: If gcc 12 proves too disruptive to compiling the distribution we could revert to gcc 11.
+<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 <!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
-* Contingency deadline: N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Contingency deadline: Fedora mass rebuild on 2022-01-19. <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 <!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
-* Blocks release? N/A (not a System Wide Change), Yes/No <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Blocks release? Yes, upgrading to the gcc 12 release blocks the release. Yes, upgrading to glibc 2.35 does block the release. <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 == Documentation ==
 <!-- Is there upstream documentation on this change, or notes you have written yourself?  Link to that material here so other interested developers can get involved. -->
+The gcc 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.
 <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-N/A (not a System Wide Change)
 == Release Notes ==
@@ Line 182: / Line 189: @@
 Release Notes are not required for initial draft of the Change Proposal but has to be completed by the Change Freeze.
 -->
+The GNU Compiler Collection version 12 is soon to be released. See https://gcc.gnu.org/gcc-12/changes.html.
+The GNU C Library version 2.35 will be released at the beginning of August 2021. 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

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