oss-fuzz: build is broken #33232

1. 
   fanquake commented at 10:02 am on August 21, 2025: member

   Now that #31802 is merged, oss-fuzz needs fixing, to either opt-out of multiprocess, or configure depends to use the pre-built Clang for native package compilation (as Ubuntu 20.04 ships with GCC 9):

    0/src/bitcoin-core/depends/work/download/native_capnp-1.2.0/capnproto-cxx-1.2.0.tar.gz.temp: OK
    1Extracting native_capnp...
    2/src/bitcoin-core/depends/sources/capnproto-cxx-1.2.0.tar.gz: OK
    3Preprocessing native_capnp...
    4Configuring native_capnp...
    5-- The CXX compiler identification is GNU 9.4.0
    6-- Detecting CXX compiler ABI info
    7-- Detecting CXX compiler ABI info - failed
    8-- Check for working CXX compiler: /usr/bin/g++
    9-- Check for working CXX compiler: /usr/bin/g++ - broken
   10CMake Error at /usr/local/share/cmake-3.29/Modules/CMakeTestCXXCompiler.cmake:60 (message):
   11  The C++ compiler
   12
   13    "/usr/bin/g++"
   14
   15  is not able to compile a simple test program.
   16
   17  It fails with the following output:
   18
   19    Change Dir: '/src/bitcoin-core/depends/work/build/x86_64-pc-linux-gnu/native_capnp/1.2.0-b8ef312d3bf/CMakeFiles/CMakeScratch/TryCompile-8xnY4X'
   20    
   21    Run Build Command(s): /usr/local/bin/cmake -E env VERBOSE=1 /usr/bin/make -f Makefile cmTC_a7435/fast
   22    make[1]: Entering directory '/src/bitcoin-core/depends/work/build/x86_64-pc-linux-gnu/native_capnp/1.2.0-b8ef312d3bf/CMakeFiles/CMakeScratch/TryCompile-8xnY4X'
   23    /usr/bin/make  -f CMakeFiles/cmTC_a7435.dir/build.make CMakeFiles/cmTC_a7435.dir/build
   24    make[2]: Entering directory '/src/bitcoin-core/depends/work/build/x86_64-pc-linux-gnu/native_capnp/1.2.0-b8ef312d3bf/CMakeFiles/CMakeScratch/TryCompile-8xnY4X'
   25    Building CXX object CMakeFiles/cmTC_a7435.dir/testCXXCompiler.cxx.o
   26    /usr/bin/g++   -I/src/bitcoin-core/depends/x86_64-pc-linux-gnu/native/include       -pipe -std=c++20  -fPIE -o CMakeFiles/cmTC_a7435.dir/testCXXCompiler.cxx.o -c /src/bitcoin-core/depends/work/build/x86_64-pc-linux-gnu/native_capnp/1.2.0-b8ef312d3bf/CMakeFiles/CMakeScratch/TryCompile-8xnY4X/testCXXCompiler.cxx
   27    g++: error: unrecognized command line option '-std=c++20'; did you mean '-std=c++2a'?
   28    make[2]: *** [CMakeFiles/cmTC_a7435.dir/build.make:78: CMakeFiles/cmTC_a7435.dir/testCXXCompiler.cxx.o] Error 1
   

   See also #31802 (comment).

2. 
   Sjors commented at 10:22 am on August 21, 2025: member

   Since I’m not at all familiar with oss-fuzz, I’ve gone for the simplest solution for now: https://github.com/google/oss-fuzz/pull/13854

   Once that’s merged, let’s rename this issue to “oss-fuzz: IPC support disabled”, because I do think we should add coverage.

3. 
   maflcko commented at 2:30 pm on August 22, 2025: member

   should be fixed?
4. maflcko closed this on Aug 22, 2025

   ---

5. fanquake added the label Fuzzing on Oct 30, 2025

Contributors
fanquake Sjors maflcko

Labels
Fuzzing