^CMake Error at GenInSubdir-Common.cmake:[0-9]+ \(add_custom_target\):
  Cannot find source file:

    [^
]*/Tests/RunCMake/CMP0118/GenInSubdir-WARN-build/GenInSubdir/sub.txt
Call Stack \(most recent call first\):
  GenInSubdir-WARN.cmake:[0-9]+ \(include\)
  CMakeLists.txt:[0-9]+ \(include\)