port to libc++ stdlib #1798
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port to libc++ stdlib #1798
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…recompile boost locally.
1. Environment setup
export MONAD_ROOT=/home/abhishek/monad-latest/monad
export BOOST_PREFIX=$HOME/boost-libcxx
export LIBBACKTRACE_ROOT=$HOME/libbacktrace-libcxx
2. Build libbacktrace (static, libc++)
cd $HOME
git clone https://github.com/ianlancetaylor/libbacktrace.git
cd libbacktrace
./configure CC=clang-19 CFLAGS='-O2 -fPIC' --prefix=$LIBBACKTRACE_ROOT
make -j$(nproc)
make install
3. Build Boost 1.83.0 against libc++
cd $HOME
curl -LO https://archives.boost.io/release/1.83.0/source/boost_1_83_0.tar.bz2
tar xf boost_1_83_0.tar.bz2
cd boost_1_83_0
./bootstrap.sh --with-toolset=clang --prefix=$BOOST_PREFIX
./b2 toolset=clang-19 \
cxxflags="-stdlib=libc++ -march=haswell -fPIC -I$LIBBACKTRACE_ROOT/include" \
linkflags="-stdlib=libc++ -L$LIBBACKTRACE_ROOT/lib" \
--with-context --with-fiber --with-stacktrace \
--with-filesystem --with-json --with-container --with-atomic --with-thread \
-sLIBBACKTRACE_PATH=$LIBBACKTRACE_ROOT \
install -j$(nproc)
4. Reconfigure the project for libc++
cd $MONAD_ROOT
python3 - <<'PY'
import shutil, os
shutil.rmtree('build', ignore_errors=True)
os.mkdir('build')
PY
cmake -S . -B build -G Ninja \
-DCMAKE_C_COMPILER=/usr/bin/clang-19 \
-DCMAKE_CXX_COMPILER=/usr/bin/clang++-19 \
-DCMAKE_C_FLAGS='-march=haswell' \
-DCMAKE_CXX_FLAGS='-march=haswell -stdlib=libc++' \
-DCMAKE_PREFIX_PATH=$BOOST_PREFIX \
-DLIBBACKTRACE_ROOT=$LIBBACKTRACE_ROOT \
-Dboost_context_DIR=$BOOST_PREFIX/lib/cmake/boost_context-1.83.0 \
-Dboost_fiber_DIR=$BOOST_PREFIX/lib/cmake/boost_fiber-1.83.0 \
-Dboost_stacktrace_backtrace_DIR=$BOOST_PREFIX/lib/cmake/boost_stacktrace_backtrace-1.83.0 \
-Dboost_stacktrace_addr2line_DIR=$BOOST_PREFIX/lib/cmake/boost_stacktrace_addr2line-1.83.0 \
-Dboost_stacktrace_basic_DIR=$BOOST_PREFIX/lib/cmake/boost_stacktrace_basic-1.83.0 \
-Dboost_filesystem_DIR=$BOOST_PREFIX/lib/cmake/boost_filesystem-1.83.0 \
-Dboost_json_DIR=$BOOST_PREFIX/lib/cmake/boost_json-1.83.0 \
-Dboost_container_DIR=$BOOST_PREFIX/lib/cmake/boost_container-1.83.0 \
-Dboost_atomic_DIR=$BOOST_PREFIX/lib/cmake/boost_atomic-1.83.0 \
-Dboost_thread_DIR=$BOOST_PREFIX/lib/cmake/boost_thread-1.83.0 \
-DBoost_USE_STATIC_LIBS=ON \
-DBoost_USE_STATIC_RUNTIME=OFF
5. **Build**
```bash
./scripts/build.sh # (or plain `ninja -C build`)
That reproduces exactly the libc++ toolchain we just set up (Boost + libbacktrace in $HOME, Clang 19, -stdlib=libc++).
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mostly done by codex-cli
it builds successfully on my machine and all tests pass.
for that, I needed to build boost and libfuzzer from sources using libc++, the CI here may not be doing that
3 third_party libraries also needed to be patched (intx, evmc, sikpre). the submodule commits referenced in this PR are in forks under my github account.
ideally, our code should build with both libc++ and libstdc++
Detailed build instructions:
• Prereqs
libbacktrace
Boost (1.83) with libc++ + libbacktrace
cxxflags="-stdlib=libc++ -fPIC -O2 -g -DBOOST_STACKTRACE_USE_BACKTRACE -I$HOME/libbacktrace-libcxx/include"
linkflags="-stdlib=libc++ -L$HOME/libbacktrace-libcxx/lib -lbacktrace"
libFuzzer runtime (compiler-rt only)
-DCMAKE_INSTALL_PREFIX=$HOME/libfuzzer-libcxx -DCMAKE_BUILD_TYPE=Release
-DCMAKE_C_COMPILER=clang-19 -DCMAKE_CXX_COMPILER=clang++-19
-DCMAKE_C_FLAGS="-stdlib=libc++ -O2 -fPIC" -DCMAKE_CXX_FLAGS="-stdlib=libc++ -O2 -fPIC"
-DCOMPILER_RT_BUILD_LIBFUZZER=ON -DCOMPILER_RT_BUILD_SANITIZERS=OFF -DCOMPILER_RT_BUILD_PROFILE=OFF
-DCOMPILER_RT_BUILD_BUILTINS=OFF -DCOMPILER_RT_BUILD_MEMPROF=OFF -DCOMPILER_RT_BUILD_GWP_ASAN=OFF
Project configure/build
From repo root:
export CC=clang-19
export CXX=clang++-19
export CMAKE_BUILD_TYPE=RelWithDebInfo
export CMAKE_PREFIX_PATH=$HOME/boost-libcxx
export LIBBACKTRACE_ROOT=$HOME/libbacktrace-libcxx
export LIBFUZZER_RUNTIME_PATH=$HOME/libfuzzer-libcxx/lib/linux/libclang_rt.fuzzer-x86_64.a
export CFLAGS="-march=haswell -stdlib=libc++"
export CXXFLAGS="-march=haswell -stdlib=libc++"
./scripts/configure.sh
./scripts/build.sh
(The configure script forwards the environment-set flags and installs -include category/core/char_traits.hpp automatically.)
Testing