title: Verbose cmake: How to get more diagnostics?
body: <p>I am getting some strange error from cmake :</p>
  
  <pre><code>loading initial cache file ../../Tweaks/compiler-rt/arm.txt
  -- Performing Test COMPILER_RT_HAS_FPIE_FLAG
  CMake Error at CMakeLists.txt:2 (set):
    Syntax error in cmake code at
  
      D:/Work/AcSo/Views/llvmSecond/build-arm/compiler-rt/CMakeFiles/CMakeTmp/CMakeLists.txt:2
  
    when parsing string
  
      D:/Work/AcSo/Views/llvmSecond/llvm/projects/compiler-rt/cmake;D:/Work/AcSo/Views/llvmSecond/llvm/projects/compiler-rt/cmake/Modules;D:/Work/AcSo/Views/llvmSecond/llvm/cmake;D:\Work\AcSo\Views\llvmSecond\build-host\Release\lib\cmake\llvm
  
    Invalid character escape '\W'.
  
  
  CMake Error: Internal CMake error, TryCompile configure of cmake failed
  -- Configuring incomplete, errors occurred!
  See also "D:/Work/AcSo/Views/llvmSecond/build-arm/compiler-rt/CMakeFiles/CMakeOutput.log".
  </code></pre>
  
  <p>All I could understand is that it gets a windows path somehow, and then complains about <code>\W</code> character sequence. Actually I've done what I could to give cmake Linux paths. So I don't know where the Windows path comes from. Nothing seems essential for this error in <code>CMakeOutput.log</code></p>
  
  <p>I would like to get more diagnostics from cmake, i.e. what and why it does, but searching for "cmake verbose" instead gives results about making the <code>make</code> verbose, not cmake itself.</p>
  
  <p>Is there a way to force cmake verbose / get more diagnostics / debug or trace output? Or if you can tell what's the problem in my specific case, that's appreciated too.</p>