CMake: resolving build error "string sub-command REGEX, mode REPLACE needs ... "

[rileyjmurray]

(We know that RandLAPACK's CMake build system needs work. I'm just mentioning this issue for those who run into it until we overhaul our CMake.)

If you change something in CMakeCache.txt or if you re-run cmake with different arguments, you might get errors like the following:

CMake Error at CMake/rl_version.cmake:16 (string):
  string sub-command REGEX, mode REPLACE needs at least 6 arguments total to
  command.
Call Stack (most recent call first):
  CMakeLists.txt:43 (include)


CMake Error at CMake/rl_version.cmake:19 (string):
  string sub-command REGEX, mode REPLACE needs at least 6 arguments total to
  command.
Call Stack (most recent call first):
  CMakeLists.txt:43 (include)


CMake Error at CMake/rl_version.cmake:22 (string):
  string sub-command REGEX, mode REPLACE needs at least 6 arguments total to
  command.
Call Stack (most recent call first):
  CMakeLists.txt:43 (include)

These errors are resolved by obliterating all CMake files that are currently in your build directory, and starting from scratch with the CMake configuration line you want.