Re: [Buildroot] [PATCH 1/2] package/llvm-project/libclc: fix build with llvm 23

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello,

On Tue, Oct 13, 2026 at 11:58:24PM +0200, Bernd Kuhls wrote:
> Buildroot commit 5f79161e4a8756acdb25c8500de9b2dee663f2ac bumped the
> llvm packages from 22.1.8 to 23.1.0 causing configure errors with the
> libclc package:
> 
> -- Check for working CLC compiler: /usr/bin/gcc
> CMake Error at cmake/modules/CMakeTestCLCCompiler.cmake:29 (message):
>   The CLC compiler
> 
>     /usr/bin/gcc
> 
>   is not able to compile a simple OpenCL test program.
> 
>   Output:
> 
>   gcc: error: unrecognized command-line option
>   '--target=spirv64-unknown-unknown'
> 
> Update various configure options to detect the correct host compiler.
> 
> Add post install hooks to create symlink which is needed for mesa3d to
> detect libclc.
> Fixes tests.package.test_mesa3d.TestMesa3DRusticl.test_run:
> 
> Libclc failed to load. Please make sure it is installed and provides
>                 spirv-mesa3d-.spv and/or spirv64-mesa3d-.spv
> 
> For details see
> https://gitlab.archlinux.org/archlinux/packaging/packages/libclc/-/commit/ca75c4b19c76ae856a368d070d914b12f71203a5#line_9b9baac1e_A71
> 
> Fixes:
> https://autobuild.buildroot.net/results/3fc/3fcdcb71be590b090df2f765c68aeaecc44dd215/
> 
> Signed-off-by: Bernd Kuhls <bernd@kuhls.net>

Thanks for having looked at this problem. Some questions below.

> ---
>  package/llvm-project/libclc/libclc.mk | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/package/llvm-project/libclc/libclc.mk b/package/llvm-project/libclc/libclc.mk
> index ff00871747..cefdca63d4 100644
> --- a/package/llvm-project/libclc/libclc.mk
> +++ b/package/llvm-project/libclc/libclc.mk
> @@ -36,13 +36,28 @@ LIBCLC_CONF_OPTS = \
>  	-DCMAKE_EXE_LINKER_FLAGS="$(HOST_LDFLAGS)" \
>  	-DCMAKE_SHARED_LINKER_FLAGS="$(HOST_LDFLAGS)" \
>  	-DCMAKE_MODULE_LINKER_FLAGS="$(HOST_LDFLAGS)" \
> -	-DCMAKE_C_COMPILER="$(CMAKE_HOST_C_COMPILER)" \
> -	-DCMAKE_CXX_COMPILER="$(CMAKE_HOST_CXX_COMPILER)" \

So we were using gcc

> +	-DCMAKE_C_COMPILER="$(HOST_DIR)/bin/clang" \
> +	-DCMAKE_CXX_COMPILER="$(HOST_DIR)/bin/clang" \

and now we're using clang? Is that what the change is about?

>  	-DLLVM_CMAKE_DIR="$(HOST_DIR)/lib/cmake/llvm" \
> +	-DLIBCLC_TARGET=spirv64-unknown-unknown \
>  	-DLIBCLC_CUSTOM_LLVM_TOOLS_BINARY_DIR="$(HOST_DIR)/bin"
>  
>  HOST_LIBCLC_CONF_OPTS = \
> -	-DLIBCLC_TARGETS_TO_BUILD=spirv64-mesa3d-
> +	-DCMAKE_C_COMPILER_FORCED=ON \
> +	-DCMAKE_CXX_COMPILER_FORCED=ON \
> +	-DCMAKE_C_COMPILER="$(HOST_DIR)/bin/clang" \
> +	-DCMAKE_CXX_COMPILER="$(HOST_DIR)/bin/clang" \
> +	-DLIBCLC_TARGET=spirv64-unknown-unknown

Is it correct to have the same -DLIBCLC_TARGET=spirv64-unknown-unknown
value passed to both the host and target package? What does that
do/mean excactly?

> +define LIBCLC_LINK_STAGING_SPV
> +	ln -sf spirv64-unknown-unknown/libclc.spv $(STAGING_DIR)/usr/share/clc/spirv64-mesa3d-.spv
> +endef
> +LIBCLC_POST_INSTALL_STAGING_HOOKS += LIBCLC_LINK_STAGING_SPV
> +
> +define LIBCLC_LINK_TARGET_SPV
> +	ln -sf spirv64-unknown-unknown/libclc.spv $(TARGET_DIR)/usr/share/clc/spirv64-mesa3d-.spv
> +endef
> +LIBCLC_POST_INSTALL_TARGET_HOOKS += LIBCLC_LINK_TARGET_SPV

A comment above those, perhaps replicating the comment from the
ArchLinux package, would be good to have.

Thanks!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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