CMake: How to use LINK_INTERFACE_MULTIPLICITY? - cmake

Question

Linking against the Intel MKL static libraries introduces circular dependencies. When I import the libraries,
set(LIBRARIES mkl_intel_lp64 mkl_sequential mkl_core)
foreach(_lib ${LIBRARIES})
add_library(${_lib} UNKNOWN IMPORTED)
set_target_properties(${_lib} PROPERTIES IMPORTED_LOCATION
/opt/intel/mkl/lib/intel64/lib${_lib}.a)
endforeach()
and link to my executable,
target_link_libraries(main PRIVATE ${LIBRARIES})
I get a ton of undefined references to the linear algebra calls. For example,
ztrevc3_gen.f:(.text+0x1af7): undefined reference to `mkl_blas_zdscal'
One way to get around this is to use the appropriate linker flags:
target_link_libraries(main PRIVATE -Wl,--start-group ${LIBRARIES} -Wl,--end-group)
Another option is to do this:
target_link_libraries(main PRIVATE ${LIBRARIES} ${LIBRARIES} ${LIBRARIES})
However, as I was searching for a more elegant solution I came across the LINK_INTERFACE_MULTIPLICITY property. If set this property along with the imported library location,
set(LIBRARIES mkl_intel_lp64 mkl_sequential mkl_core)
foreach(_lib ${LIBRARIES})
add_library(${_lib} UNKNOWN IMPORTED)
set_target_properties(${_lib} PROPERTIES IMPORTED_LOCATION
/opt/intel/mkl/lib/intel64/lib${_lib}.a
LINK_INTERFACE_MULTIPLICITY 3)
endforeach()
I get the same undefined references as before, so appearently this is not working. What is the proper way to use LINK_INTERFACE_MULTIPLICITY and is there a more elegant way to get around circular dependencies?
EDIT
Here is a minimal example that fails, this time with the correct IMPORTED_LINK_INTERFACE_MULTIPLICITY variable.
# CMakeLists.txt
cmake_minimum_required(VERSION 3.10)
project(test Fortran)
add_executable(main main.f90)
set(LIBRARIES mkl_intel_lp64 mkl_sequential mkl_core)
foreach(_lib ${LIBRARIES})
add_library(${_lib} UNKNOWN IMPORTED)
set_target_properties(${_lib} PROPERTIES IMPORTED_LOCATION
/opt/intel/mkl/lib/intel64/lib${_lib}.a
IMPORTED_LINK_INTERFACE_MULTIPLICITY 3)
endforeach()
list(APPEND LIBRARIES dl pthread)
target_link_libraries(main ${LIBRARIES})
#target_link_libraries(main ${LIBRARIES} ${LIBRARIES} ${LIBRARIES})
# main.f90
call zpotrf
end program
If you uncomment the last line then the build succeeds. Unfortunately, the MKL in not free (except in some cases) but hopefully somebody can test this. I should note that it fails with some linear algebra calls and not others like dgemm.

Answer 1

Property LINK_INTERFACE_MULTIPLICITY is for "normal" STATIC library. For IMPORTED library IMPORTED_LINK_INTERFACE_MULTIPLICITY property should be used instead:
set_target_properties(${_lib} PROPERTIES
IMPORTED_LOCATION /opt/intel/mkl/lib/intel64/lib${_lib}.a
IMPORTED_LINK_INTERFACE_MULTIPLICITY 3)