Is building with clang supported?

[OfekShilon]

I have clang-14 installed and wanted to use it. I did export CXXFLAGS="-stdlib=libc++" and
./helio/blaze.sh -release -clang which seem to have passed, but ninja dragonfly bombarded me with many errors. Start of dump:

FAILED: third_party/src/gperf_project-stamp/gperf_project-build third_party/libs/gperf/lib/libprofiler.a
cd /home/ofek/src/dragonfly/clang-opt/third_party/src/gperf_project-build && /usr/bin/cmake -P /home/ofek/src/dragonfly/clang-opt/third_party/src/gperf_project-stamp/gperf_project-build-Release.cmake && /usr/bin/cmake -E touch /home/ofek/src/dragonfly/clang-opt/third_party/src/gperf_project-stamp/gperf_project-build
CMake Error at /home/ofek/src/dragonfly/clang-opt/third_party/src/gperf_project-stamp/gperf_project-build-Release.cmake:49 (message):
  Command failed: 2

   'make' '-j4'

  See also

    /home/ofek/src/dragonfly/clang-opt/third_party/src/gperf_project-stamp/gperf_project-build-*.log
...

dragonfly/clang-opt/third_party/src/gperf_project-stamp/gperf_project-build-err.log starts with:

Makefile:4264: warning: overriding recipe for target 'heap-checker_debug_unittest.sh'
Makefile:4260: warning: ignoring old recipe for target 'heap-checker_debug_unittest.sh'
Makefile:4288: warning: overriding recipe for target 'heap-profiler_debug_unittest.sh'
Makefile:4284: warning: ignoring old recipe for target 'heap-profiler_debug_unittest.sh'
Makefile:4494: warning: overriding recipe for target 'sampling_debug_test.sh'
Makefile:4490: warning: ignoring old recipe for target 'sampling_debug_test.sh'
/home/ofek/src/dragonfly/clang-opt/third_party/gperf/benchmark/malloc_bench.cc:32:10: fatal error: 'algorithm' file not found
#include <algorithm>
         ^~~~~~~~~~~
1 error generated.
...

What is the state of support for clang? blaze.sh does include a -clang switch but it is undocumented. Is there a point in trying to sort through these errors or is clang just not supported?

[romange]

Hi @OfekShilon , it should work. Why do you need to export cxxflags?
Did you try without the export?

[OfekShilon]

@romange gcc build succeeds, Clang build without any flags fails with:

ofek@ofek-lap:~/src/dragonfly$ ./helio/blaze.sh -release -clang
Using launcher /usr/bin/ccache
+ cmake -L -B clang-opt -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=/usr/bin/clang++ -GNinja -DCMAKE_CXX_COMPILER_LAUNCHER=/usr/bin/ccache
-- The CXX compiler identification is Clang 14.0.6
-- Check for working CXX compiler: /usr/bin/clang++
-- Check for working CXX compiler: /usr/bin/clang++ -- broken
CMake Error at /usr/share/cmake-3.16/Modules/CMakeTestCXXCompiler.cmake:53 (message):
  The C++ compiler

    "/usr/bin/clang++"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: /home/ofek/src/dragonfly/clang-opt/CMakeFiles/CMakeTmp

    Run Build Command(s):/usr/bin/ninja cmTC_7368d && [1/2] Building CXX object CMakeFiles/cmTC_7368d.dir/testCXXCompiler.cxx.o
    [2/2] Linking CXX executable cmTC_7368d
    FAILED: cmTC_7368d
    : && /usr/bin/clang++     CMakeFiles/cmTC_7368d.dir/testCXXCompiler.cxx.o  -o cmTC_7368d   && :
    /usr/bin/ld: cannot find -lstdc++
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    ninja: build stopped: subcommand failed.
    ...

So I added the -stdlib=libc++ flag, blaze.sh succeeded but was followed by the build errors I pasted above. I'll try to debug them later
(also contacted you directly on Linkedin..)

[romange]

Ofek, I've tried running clang-12 on my machine (ubuntu 20.04) and it does not encounter the problems you mentioned.
There were indeed some compile errors under clang but nothing like in the snippet. And anyway, I fixed those errors in this PR #290 .

[OfekShilon]

Thanks Roman! I'll give it another go over the weekend.

[safa-topal]

Facing similar issue with 1.11.0 on Fedora 37,38. Is there a chance of a dependency change between 1.9.0 and 1.11.0? Our builds works fine on 1.9.0.

+ cmake -L -B build-opt -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=g++ -GNinja -DCMAKE_CXX_COMPILER_LAUNCHER=/usr/bin/ccache '-DHELIO_RELEASE_FLAGS=-g1 -gz' '-DCMAKE_EXE_LINKER_FLAGS=-lz -static-libstdc++ -static-libgcc' -DBoost_USE_STATIC_LIBS=OFF -DOPENSSL_USE_STATIC_LIBS=OFF -DENABLE_GIT_VERSION=ON -DWITH_UNWIND=OFF -DMARCH_OPT=
-- The C compiler identification is GNU 12.3.1
-- The CXX compiler identification is GNU 12.3.1
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/lib64/ccache/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - failed
-- Check for working CXX compiler: /usr/lib64/ccache/g++
-- Check for working CXX compiler: /usr/lib64/ccache/g++ - broken
CMake Error at /usr/share/cmake/Modules/CMakeTestCXXCompiler.cmake:60 (message):
  The C++ compiler
    "/usr/lib64/ccache/g++"
  is not able to compile a simple test program.
  It fails with the following output:

    Change Dir: '/deps-f37-aarch64/rpmbuild/BUILD/dragonfly-1.11.0/build-opt/CMakeFiles/CMakeScratch/TryCompile-Fir1WU'
    Run Build Command(s): /usr/bin/ninja-build -v cmTC_153c8
    [1/2] /usr/lib64/ccache/g++    -o CMakeFiles/cmTC_153c8.dir/testCXXCompiler.cxx.o -c /deps-f37-aarch64/rpmbuild/BUILD/dragonfly-1.11.0/build-opt/CMakeFiles/CMakeScratch/TryCompile-Fir1WU/testCXXCompiler.cxx
    [2/2] : && /usr/lib64/ccache/g++  -lz -static-libstdc++ -static-libgcc CMakeFiles/cmTC_153c8.dir/testCXXCompiler.cxx.o -o cmTC_153c8   && :
    FAILED: cmTC_153c8 
    : && /usr/lib64/ccache/g++  -lz -static-libstdc++ -static-libgcc CMakeFiles/cmTC_153c8.dir/testCXXCompiler.cxx.o -o cmTC_153c8   && :
    /usr/bin/ld: cannot find -lstdc++: No such file or directory
    collect2: error: ld returned 1 exit status
    ninja: build stopped: subcommand failed.

[kostasrim]

Hi @safa-topal, it seems like the issue is that it can't find the static libstdc++.

Can you plz try:

sudo dnf install glibc-static libstdc++-static -y

and let me know?

[safa-topal]

Hey @kostasrim, worked like charm! Much appreciated.

[kostasrim]

Lit, I will patch our docs as well. Thank you for reporting this!

[romange]

@safa-topal we publish prebuilt fedora packages:
see dragonfly.x86_64.rpm
from here: https://github.com/dragonflydb/dragonfly/releases/tag/v1.11.0