1> Command line: C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO\2017\COMMUNITY\COMMON7\IDE\COMMONEXTENSIONS\MICROSOFT\CMAKE\CMake\bin\cmake.exe -G "Visual Studio 15 2017 Win64" -DCMAKE_INSTALL_PREFIX:PATH="C:\Users\Stephen\AppData\Local\CMakeBuild\01ec6fa0-891c-e932-b1f6-102a4aedd859\build\install" -DCMAKE_CONFIGURATION_TYPES="Release" "C:\Users\Stephen\Source\Repos\Celestia\thirdparty\Eigen\Eigen"
1> Working directory: C:\Users\Stephen\AppData\Local\CMakeBuild\01ec6fa0-891c-e932-b1f6-102a4aedd859\build\x64-Release
1> CMake Error at C:\Users\Stephen\Source\Repos\Celestia\thirdparty\Eigen\Eigen\CMakeLists.txt:1 (include):
1> include could not find load file:
1>
1> RegexUtils
1>
1>
1> CMake Error at C:\Users\Stephen\Source\Repos\Celestia\thirdparty\Eigen\Eigen\CMakeLists.txt:2 (test_escape_string_as_regex):
1> Unknown CMake command "test_escape_string_as_regex".
Can someone tell me what I've missed? - this was a fresh clone.