title: CMake/MinGW unknown compilers, gcc.exe broken
body: <p>I am trying to install on my windows desktop, a software suite called NUPACK which is used to design nucleic acid reaction pathways. <a href="http://www.nupack.org/" rel="noreferrer">http://www.nupack.org/</a></p>
  
  <p>This software requires CMake to install, and from my understanding, CMake does not have compilers by itself, and requires us to have compilers separately installed. As such, I downloaded MinGW to use as a C++ compiler. Prior to running, I have set the environment variables of both CMake and MinGW's bin. I am running CMake (version 3.11.1) through the command prompt but I keep encountering the following problem:</p>
  
  <pre><code>C:\Users\Nicholas\Documents\nupack\build&gt;Cmake -DCMAKE_INSTALL_PREFIX=NUPACKINSTALL -G "MinGW Makefiles" ..
  -- The C compiler identification is unknown
  -- The CXX compiler identification is unknown
  -- Check for working C compiler: C:/MinGW/bin/gcc.exe
  -- Check for working C compiler: C:/MinGW/bin/gcc.exe -- broken
  CMake Error at C:/Program Files/CMake/share/cmake- 
  3.11/Modules/CMakeTestCCompiler.cmake:52 (message):
    The C compiler
  
      "C:/MinGW/bin/gcc.exe"
  
    is not able to compile a simple test program.
  </code></pre>
  
  <p>I'm guessing CMake cannot identify my MinGW gcc and gcc++ compilers somehow. I tried the following next, but the same error arose.</p>
  
  <pre><code>set CMAKE_C_COMPILER=%C:\mingw\bin\gcc%
  set CMAKE_CXX_COMPILER=%C:\mingw\bin\g++%
  </code></pre>
  
  <p>Has anyone encountered the same problem? Can this be resolved by using MinGW64? I am using Windows 10 and previously, I tried using visual studio 2017's compilers, but it had its on set of problems too. </p>