hardcoded lib path breaks OpenBLASConfig.cmake

[negril]

In #5035 ${OPENBLAS_LIBRARY_DIR} was replaced by \$${_OpenBLAS_ROOT_DIR}/lib calling it an "improvement" without any rationale given as to why. Yet it renders the established and still used variables OPENBLAS_LIBRARY_DIR and OPENBLAS_INCLUDE_DIR partially ineffective.

This breaks the cmake config file on at least linux multilib systems, where 64 bit libraries are often installed in different paths like /usr/lib64.

When calling make install OPENBLAS_INCLUDE_DIR=/usr/include/openblas OPENBLAS_LIBRARY_DIR=/usr/lib64, it installs the library as /usr/lib64/libopenblas.so, but generates:

SET(OpenBLAS_VERSION "0.3.30")
file(REAL_PATH "../../.." _OpenBLAS_ROOT_DIR BASE_DIRECTORY ${CMAKE_CURRENT_LIST_DIR} )
SET(OpenBLAS_INCLUDE_DIRS ${_OpenBLAS_ROOT_DIR}/include)
SET(OpenBLAS_LIBRARIES ${_OpenBLAS_ROOT_DIR}/lib/libopenblas.so)

[martin-frbg]

Well if you look in the linked #4396 this appears to be a conflict between platform conventions (or ad-hoc conventions), perhaps this should be conditional on which variable is found to be non-empty at invocation of make install ?

[negril]

b9da1ad that's the local patch I used. Creating the unprefixed path is necessary as PREFIX is passed with OPENBLAS_*_DIR.