Projects using cmake and requiring llvm stopped working with llvm6 with the
following error:

[  173s] CMake Error at /usr/lib64/cmake/llvm/LLVMExports.cmake:271 (message):
[  173s]   The imported target "PollyISL" references the file
[  173s] 
[  173s]      "/usr/lib64/libPollyISL.a"
[  173s] 
[  173s]   but this file does not exist.  Possible reasons include:
[  173s] 
[  173s]   * The file was deleted, renamed, or moved to another location.
[  173s] 
[  173s]   * An install or uninstall procedure did not complete successfully.
[  173s] 
[  173s]   * The installation package was faulty and contained
[  173s] 
[  173s]      "/usr/lib64/cmake/llvm/LLVMExports.cmake"

Example package:
https://build.opensuse.org/package/show/home:darix:darktable:master/darktable