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[libc++] Updates the compilers used post LLVM-20 branching. #126564

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Merged
merged 2 commits into from
Feb 18, 2025
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[libc++] Updates the compilers used post LLVM-20 branching. #126564

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cb49571
[libc++] Updates the compilers used post LLVM-20 branching.
mordante Feb 10, 2025
bd0d864
Fixes CI.
mordante Feb 12, 2025
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28 changes: 16 additions & 12 deletions .github/workflows/libcxx-build-and-test.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ jobs:
stage1:
if: github.repository_owner == 'llvm'
runs-on: libcxx-self-hosted-linux
container: ghcr.io/llvm/libcxx-linux-builder:d8a0709b1090350a7fe3604d8ab78c7d62f10698
container: ghcr.io/llvm/libcxx-linux-builder:b319dfef21f6c7b0bc6a356d6b9f41a3b3b98ae9
continue-on-error: false
strategy:
fail-fast: false
Expand All @@ -48,8 +48,8 @@ jobs:
'generic-cxx26',
'generic-modules'
]
cc: [ 'clang-20' ]
cxx: [ 'clang++-20' ]
cc: [ 'clang-21' ]
cxx: [ 'clang++-21' ]
include:
- config: 'generic-gcc'
cc: 'gcc-14'
Expand All @@ -75,7 +75,7 @@ jobs:
stage2:
if: github.repository_owner == 'llvm'
runs-on: libcxx-self-hosted-linux
container: ghcr.io/llvm/libcxx-linux-builder:d8a0709b1090350a7fe3604d8ab78c7d62f10698
container: ghcr.io/llvm/libcxx-linux-builder:b319dfef21f6c7b0bc6a356d6b9f41a3b3b98ae9
needs: [ stage1 ]
continue-on-error: false
strategy:
Expand All @@ -88,18 +88,22 @@ jobs:
'generic-cxx20',
'generic-cxx23'
]
cc: [ 'clang-20' ]
cxx: [ 'clang++-20' ]
cc: [ 'clang-21' ]
cxx: [ 'clang++-21' ]
include:
- config: 'generic-gcc-cxx11'
cc: 'gcc-14'
cxx: 'g++-14'
- config: 'generic-cxx23'
cc: 'clang-18'
cxx: 'clang++-18'
- config: 'generic-cxx26'
cc: 'clang-20'
cxx: 'clang++-20'
- config: 'generic-cxx26'
cc: 'clang-19'
cxx: 'clang++-19'
# Release transition
- config: 'generic-cxx23'
cc: 'clang-18'
cxx: 'clang++-18'
Comment on lines +103 to +106
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Do we really need this? I don't think there is much code that requires clang-18-specific workarounds currently and it's really not clear to me when we should drop it otherwise.

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Yes we need this. At the moment patches get actively backported to the release branch. Testing clang-18 enures that backporting is easy to do. Once LLVM 20.1.0 is released we can drop clang-18. (We've been doing this is the past too.)

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I agree with @mordante, this is easy to keep around for a few weeks and it reduces friction when backporting.

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I don't remember any rules on this and I though it was around for quite a while sometimes. If we agree that it can go after the initial release I'm fine with it, but I really don't want to keep it around for the whole cycle, since that would effectively extend our supported compilers by one version.

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It's indeed only for the release transition.

steps:
- uses: actions/checkout@v4
- name: ${{ matrix.config }}
Expand Down Expand Up @@ -163,14 +167,14 @@ jobs:
- config: 'generic-msan'
machine: libcxx-self-hosted-linux
runs-on: ${{ matrix.machine }}
container: ghcr.io/llvm/libcxx-linux-builder:d8a0709b1090350a7fe3604d8ab78c7d62f10698
container: ghcr.io/llvm/libcxx-linux-builder:b319dfef21f6c7b0bc6a356d6b9f41a3b3b98ae9
steps:
- uses: actions/checkout@v4
- name: ${{ matrix.config }}
run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
env:
CC: clang-20
CXX: clang++-20
CC: clang-21
CXX: clang++-21
- uses: actions/upload-artifact@26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
if: always()
with:
Expand Down
16 changes: 8 additions & 8 deletions libcxx/docs/index.rst
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Expand Up @@ -128,14 +128,14 @@ Libc++ aims to support common compilers that implement the C++11 Standard. In or
good balance between stability for users and maintenance cost, testing coverage and development
velocity, libc++ drops support for older compilers as newer ones are released.

============ =============== ========================== =====================
Compiler Versions Restrictions Support policy
============ =============== ========================== =====================
Clang 17, 18, 19-git latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_ and the development version
AppleClang 15 latest stable release per `Xcode's release page <https://developer.apple.com/documentation/xcode-release-notes>`_
Open XL 17.1 (AIX) latest stable release per `Open XL's documentation page <https://www.ibm.com/docs/en/openxl-c-and-cpp-aix>`_
GCC 14 In C++11 or later only latest stable release per `GCC's release page <https://gcc.gnu.org/releases.html>`_
============ =============== ========================== =====================
============ =================== ========================== =====================
Compiler Versions Restrictions Support policy
============ =================== ========================== =====================
Clang 18, 19, 20, 21-git latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_ and the development version
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I don't think we should document that we support more versions than we plan to support when this gets released.

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I prefer to keep this as is, and drop 18 when we no longer support it.

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But we don't support it anymore. This is purely around for ease of migration.

AppleClang 15 latest stable release per `Xcode's release page <https://developer.apple.com/documentation/xcode-release-notes>`_
Open XL 17.1 (AIX) latest stable release per `Open XL's documentation page <https://www.ibm.com/docs/en/openxl-c-and-cpp-aix>`_
GCC 14 In C++11 or later only latest stable release per `GCC's release page <https://gcc.gnu.org/releases.html>`_
============ =================== ========================== =====================

Libc++ also supports common platforms and architectures:

Expand Down
2 changes: 1 addition & 1 deletion libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp
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Expand Up @@ -12,7 +12,7 @@
// UNSUPPORTED: c++03

// TODO: Investigate these failures which break the CI.
// UNSUPPORTED: clang-18, clang-19, clang-20
// UNSUPPORTED: clang-18, clang-19, clang-20, clang-21
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Let's revive the patch to remove this. It's been broken for 1.5 years. If nobody cares about it, we should get rid of it.

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It's not been broken. Our CI is. This actually works for every clang version listed here, except in the CI.

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Do we know why it does not work in our CI?

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IIRC the last time it mostly worked except in the optimized build. I've disabled it for everything, since it was already the same day as the LLVM 20 branch and the test was already disabled for all the other versions. We should look into it and maybe just disable it for the optimized build.


// The Android libc++ tests are run on a non-Android host, connected to an
// Android device over adb. gdb needs special support to make this work (e.g.
Expand Down