CMake generate step failing in `Linux_amd64 src-azurelinux-3.0-net9.0-crossdeps-graph` jobs

[ellahathaway]

Several public PR builds are failing with the following error:

#8 5.342 CMake Error at /llvm-project.src/libcxx/cmake/Modules/HandleLibCXXABI.cmake:59 (add_library):
#8 5.342   No SOURCES given to target: libcxx-abi-headers-generate-private-headers

Below are three builds which have experienced the error:

• https://dev.azure.com/dnceng-public/public/_build/results?buildId=766292&view=logs&j=9451fe7a-3b19-5e32-5ae2-ab8409ac889d&t=8b49f318-ee4b-51db-c9b2-6c2579fdf8cb
• https://dev.azure.com/dnceng-public/public/_build/results?buildId=766733&view=logs&j=9451fe7a-3b19-5e32-5ae2-ab8409ac889d&t=8b49f318-ee4b-51db-c9b2-6c2579fdf8cb
• https://dev.azure.com/dnceng-public/public/_build/results?buildId=767687&view=logs&j=9451fe7a-3b19-5e32-5ae2-ab8409ac889d&t=8b49f318-ee4b-51db-c9b2-6c2579fdf8cb

I first noticed this in checks for this PR, and the errors are unrelated to the changes in that PR.

[mthalman]

This is the affected command:

dotnet-buildtools-prereqs-docker/src/azurelinux/3.0/net9.0/cross/riscv64-alpine/Dockerfile

Lines 8 to 31 in 7146e2a

	RUN TARGET_TRIPLE="riscv64-alpine-linux-musl" && \
	cmake -S llvm-project.src/runtimes -B runtimes \
	-DCMAKE_BUILD_TYPE=Release \
	-DCMAKE_ASM_COMPILER=clang \
	-DCMAKE_C_COMPILER=clang \
	-DCMAKE_CXX_COMPILER=clang++ \
	-DCMAKE_ASM_COMPILER_TARGET="$TARGET_TRIPLE" \
	-DCMAKE_C_COMPILER_TARGET="$TARGET_TRIPLE" \
	-DCMAKE_CXX_COMPILER_TARGET="$TARGET_TRIPLE" \
	# We're going to link the static libraries we build here into PIC images, so build the static libraries as PIC.
	-DCMAKE_POSITION_INDEPENDENT_CODE=ON \
	-DCMAKE_SYSROOT="$ROOTFS_DIR" \
	# Specify linker to use for exes directly for CMake toolchain detection
	-DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld" \
	# Don't search for tools in the sysroot as we're cross-compiling
	-DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM="NEVER" \
	-DLLVM_USE_LINKER=lld \
	-DLLVM_ENABLE_RUNTIMES="libcxx" \
	-DLIBCXX_ENABLE_SHARED=OFF \
	-DLIBCXX_HAS_MUSL_LIBC=ON \
	-DLIBCXX_CXX_ABI=libstdc++ \
	-DLIBCXX_CXX_ABI_INCLUDE_PATHS="$ROOTFS_DIR/usr/include/c++/13.2.1/;$ROOTFS_DIR/usr/include/c++/13.2.1/$TARGET_TRIPLE" && \
	cmake --build runtimes -j $(getconf _NPROCESSORS_ONLN) && \
	cmake --install runtimes --prefix "$ROOTFS_DIR/usr"

@am11 - Can you investigate?

[am11]

@mthalman that file is for Linux-musl-riscv64. We don’t even have a CI leg for it. These errors are occurring in other legs like linux arm.

[mthalman]

that file is for Linux-musl-riscv64. We don’t even have a CI leg for it.

Are you implying that there's no need for this Dockerfile and it can be removed?

These errors are occurring in other legs like linux arm.

Not sure what you mean by this. Can you provide a relevant link?

[am11]

OK, I was on the phone and was reading it wrong. So it has just started to fail? It wasn't failing in #1098 and many builds since, right?

[mthalman]

It just started failing recently.

[am11]

Are you implying that there's no need for this Dockerfile and it can be removed?

Even if it's not used in runtime today, we want to keep it to test the builds. I use it in github actions and others too. I will eventually add it to community pipeline (in dotnet/runtime) as well, but haven't gotten enough cycles to go about it.

[am11]

PR is up #1162.