Octave module build fails to link OpenCL with octave 9.1.0

[opoplawski]

I'm working on updating octave to 9.1.0 in Fedora Rawhide. Rebuilding the octave-mcxlab package (which uses this source) fails with:;

error: /home/orion/BUILDROOT/octave-mcxlab-2024.2-1.fc41.x86_64/usr/share/octave/packages/mcxlab-2024.2/mcxcl.mex: failed to load
Incompatible version or missing dependency?
/home/orion/BUILDROOT/octave-mcxlab-2024.2-1.fc41.x86_64/usr/share/octave/packages/mcxlab-2024.2/mcxcl.mex: undefined symbol: clBuildProgram

This is because mcxcl.mex is no longer being linked with -lOpenCL. Adding -v to mkoctfile shows:

CXXFLAGS=' ' LFLAGS='-g -L/usr/lib64/octave/9.1.0 -lOpenCL ' LDFLAGS='' mkoctfile -v mcx_host.o mcx_utils.o tictoc.o mcxcl.o mcx_shapes.o cjson/cJSON.o --mex mcxlabcl.cpp  -o ../mcxlabcl/mcxcl.mex
g++ -c   -I/usr/include/suitesparse  -I/usr/include/suitesparse -fPIC -I/usr/include/octave-9.1.0/octave/.. -I/usr/include/octave-9.1.0/octave  -pthread -fopenmp     -I.  -DMEX_DEBUG mcxlabcl.cpp -o /tmp/oct-XCR4qO.o
In file included from /usr/include/CL/cl.h:20,
                 from mcx_host.hpp:9,
                 from mcxlabcl.cpp:36:
/usr/include/CL/cl_version.h:22:104: note: ‘#pragma message: cl_version.h: CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 300 (OpenCL 3.0)’
   22 | #pragma message("cl_version.h: CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 300 (OpenCL 3.0)")
      |                                                                                                        ^
g++ -I/usr/include/octave-9.1.0/octave/.. -I/usr/include/octave-9.1.0/octave  -pthread -fopenmp    -o ../mcxlabcl/mcxcl.mex  mcx_host.o mcx_utils.o tictoc.o mcxcl.o mcx_shapes.o cjson/cJSON.o /tmp/oct-XCR4qO.o   -shared -Wl,-Bsymbolic  -L/usr/lib64 -shared -Wl,-Bsymbolic      -Wl,-z,relro -Wl,--as-needed  -Wl,-z,pack-relative-relocs -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld-errors -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -Wl,--build-id=sha1   -flto

So as you can see, none of LFLAGS ends up on the link line.

Looking at the mkoctfile man page it accepts all of those arguments as direct arguments to mkoctfile. Doing so fixes the build. I have a PR to do that.