Building libc++ instructions fail on linux

[rconde01]

Following these directions using gcc 13.1 on Redhat EL9:
https://releases.llvm.org/19.1.0/projects/libcxx/docs/BuildingLibcxx.html#id4

ninja -C build runtimes gives:

CMake Error at /home/rconde/Documents/cn2/p/b/clang4e9cde48f94f6/b/libunwind/src/CMakeLists.txt:102 (message):
  Compiler doesn't support generation of unwind tables if exception support
  is disabled.  Building libunwind DSO with runtime dependency on C++ ABI
  library is not supported.

[philnik777]

What exactly were the commands you ran?

[rconde01]

cmake --version
gcc --version
ninja --version

wget https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.0/llvm-project-19.1.0.src.tar.xz

rm -rf llvm-project-19.1.0.src

tar -xJf llvm-project-19.1.0.src.tar.xz

cd llvm-project-19.1.0.src

mkdir build

cmake -G Ninja -S llvm -B build \
   -DCMAKE_BUILD_TYPE=Release \
   -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" \
   -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind" \
   -DLLVM_RUNTIME_TARGETS="x86_64-unknown-linux-gnu"
ninja -C build runtimes

And the log is attached.

build.txt

[philnik777]

It looks like your Clang build is broken somehow. Could you check what happens when you try to build a simple test program with the just built Clang? The executable should be at build/bin/clang++. Something like int main() {} is probably enough of a test program.

[rconde01]

hmm:

/opt/rh/gcc-toolset-13/root/usr/bin/ld: cannot find crtbeginS.o: No such file or directory
/opt/rh/gcc-toolset-13/root/usr/bin/ld: cannot find -lstdc++: No such file or directory
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

I used gcc-toolset-13 to compile

[philnik777]

Ok, that's out of my field of expertise. Moving to Clang.