Repository navigation
[clang] DISABLE_LLVM_LINK_LLVM_DYLIB no longer honored after upgrade to LLVM22 when configuring with builtin_llvm=OFF #23155
Description
Check duplicate issues.
- Checked for duplicates
Description
Check duplicate issues.
- Checked for duplicates
Description
With the following snippet:
docker run -it registry.cern.ch/root-ci/ubuntu2604:buildready
apt update
apt install llvm-20 libedit-dev libpolly-20-dev
git clone https://github.com/root-project/root root_src && cd root_src
git checkout v6-40-00-patches
sed -i 's|LLVM REQUIRED|LLVM ${ROOT_LLVM_VERSION_REQUIRED_MAJOR}.1 REQUIRED|g' interpreter/CMakeLists.txt # Backport of a patch from master
mkdir build && cd build
cmake -Dbuiltin_llvm=OFF -Dminimal=ON ..
grep -r LLVM.so *
shows that LLVM is not linked via shared object libraries, as expected.
Instead, in current master:
docker run -it registry.cern.ch/root-ci/ubuntu2604:buildready
apt update
apt install llvm-22 libpolly-22-dev
git clone https://github.com/root-project/root root_src && cd root_src
mkdir build && cd build
cmake -Dbuiltin_llvm=OFF -Dminimal=ON ..
grep -r LLVM.so *
shows a lot of occurrences in grep, which is not what one would expect. Which later leads to the issue described in #12156
Ubuntu26 installs LLVM20 and LLVM22 in the same way, so it's probably not a Debian packaging issue, but rather something with LLVM22 CMakeLists.txt changes. See only minor differences:
diff --brief --recursive /usr/lib/llvm-20/lib/ /usr/lib/llvm-22/lib/ | grep Only
Only in /usr/lib/llvm-20/lib/: libLLVM-20.so
Only in /usr/lib/llvm-22/lib/: libLLVM-22.so
Only in /usr/lib/llvm-20/lib/: libLLVM.so.20.1
Only in /usr/lib/llvm-22/lib/: libLLVM.so.22.1
Only in /usr/lib/llvm-20/lib/: libLTO.so.20.1
Only in /usr/lib/llvm-22/lib/: libLTO.so.22.1
Only in /usr/lib/llvm-20/lib/: libRemarks.so.20.1
Only in /usr/lib/llvm-22/lib/: libRemarks.so.22.1
Only in /usr/lib/llvm-20/lib/: libclang-cpp.so.20.1
Only in /usr/lib/llvm-22/lib/: libclang-cpp.so.22.1
Only in /usr/lib/llvm-20/lib/cmake: polly
Only in /usr/lib/llvm-20/lib/: libPolly.a
Only in /usr/lib/llvm-20/lib/: libPollyISL.a
Only in /usr/lib/llvm-22/lib/: libLLVMABI.a
Only in /usr/lib/llvm-22/lib/: libLLVMCAS.a
Only in /usr/lib/llvm-22/lib/: libLLVMDTLTO.a
Only in /usr/lib/llvm-22/lib/: libLLVMDWARFCFIChecker.a
Only in /usr/lib/llvm-22/lib/: libLLVMDebugInfoDWARFLowLevel.a
Only in /usr/lib/llvm-22/lib/: libLLVMFrontendDirective.a
Only in /usr/lib/llvm-22/lib/: libLLVMPlugins.a
Only in /usr/lib/llvm-22/lib/: libLLVMSupportLSP.a
Reproducer
docker run -it registry.cern.ch/root-ci/ubuntu2604:buildready
apt update
apt install llvm-22 libpolly-22-dev
git clone https://github.com/root-project/root root_src && cd root_src
mkdir build && cd build
cmake -Dbuiltin_llvm=OFF -Dminimal=ON ..
make clang-tblgen -j$(nproc)
ROOT version
ROOT v6.40.02
Built for linuxx8664gcc on Jun 10 2026, 10:37:47
From tags/v6-40-02@v6-40-02
With c++ (Ubuntu 13.3.0-6ubuntu2~24.04.1) 13.3.0 std201703
Binary directory: /opt/root/bin
Installation method
Source
Operating system
Ubuntu26 Docker
Additional context
tagging @guitargeek and @vepadulano since they have experience with builtin_llvm=OFF
conda-forge/llvmdev-feedstock#357 (comment)
Metadata
Metadata
Assignees
Type
Projects
- Status
Activity
guitargeek commentedon Aug 26, 2026
It's a never-ending story, see also:
LLVM_LINK_LLVM_DYLIB=ON#18387ferdymercury commentedon Aug 26, 2026
Thanks a lot! I can confirm that your patch #18387 (comment)
solves this issue. (Even if that issue you mean is with builtin_clang=OFF whereas I use builtin_clang=ON, so not exactly duplicate).
What I do not understand is why it works ok with LLVM20 without that patch, and starts failing with LLVM22.
[clang] do not search again for LLVM if already found by parent projects
[interpreter] do not let builtin_clang search again for LLVM if built…
[interpreter] do not let builtin_clang search again for LLVM if built…
[CMake] Don't let builtin_clang search for LLVM if builtin_llvm=OFF
[CMake] Don't let builtin_clang search for LLVM if builtin_llvm=OFF