FindBLAS for Intel MKL is broken on Mac OS X.
I have a new Mac computer and do not currently have access to my old one. On the old one, finding MKL worked (I did report some issues before and they were solved in version 3.14 I believe. On my new laptop, I am using CLion which comes bundled with 3.15. I also did a fresh install of Intel MKL. Now the search fails. After investigating, I had to modify two lines in the source of FindBLAS.cmake. They were both introduced/modified in commit 89ab54c1. The first line is:
set(_BLAS_MKLROOT_LIB_DIR "$ENV{MKLROOT}/lib/intel64")
There is no (more?) subdirectory intel64 so this does not work. The second line is:
string(APPEND _BLAS_MKLROOT_LIB_DIR "_mac")
Again the path of the library does not have a _mac postfix. I do not know if this is a new MKL packaging change as I do not have access to my old computer, though from memory, I think it may be. By commenting the last line and removing intel64 from the first, everything works fine. This may not be the case with older versions of MKL, so maybe the existence of those paths should be tested instead of setting the variable indiscriminately?