尝试在Windows 7中构建nanomsg project时出现错误：

cmake ..
-- Building for: NMake Makefiles
-- The C compiler identification is GNU 4.7.1
-- Check for working C compiler: C:/Program Files (x86)/CodeBlocks/MinGW/bin/gcc.exe
CMake Error: Generator: execution of make failed. Make command was: "nmake" "/NOLOGO" "cmTC_5d837\fast"
-- Check for working C compiler: C:/Program Files (x86)/CodeBlocks/MinGW/bin/gcc.exe -- broken
CMake Error at C:/Program Files (x86)/cmake-3.9.4-win64-x64/share/cmake-3.9/Modules/CMakeTestCCompiler.cmake:51 (message):
The C compiler "C:/Program Files (x86)/CodeBlocks/MinGW/bin/gcc.exe" is not
able to compile a simple test program.

It fails with the following output:

Change Dir: C:/Users/User/Documents/Internal/nanomsg-master/build/CMakeFiles/CMakeTmp

Run Build Command:"nmake" "/NOLOGO" "cmTC_5d837\fast"

Generator: execution of make failed.  Make command was: "nmake" "/NOLOGO"
"cmTC_5d837\fast"

CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
CMakeLists.txt:29 (project)

-- Configuring incomplete, errors occurred!
See also "C:/Users/User/Documents/Internal/nanomsg-master/build/CMakeFiles/CMakeOutput.log".
See also "C:/Users/User/Documents/Internal/nanomsg-master/build/CMakeFiles/CMakeError.log".

我使用gcc编译器和Mingw工具链中的make，可以在一个简单的示例中成功运行gcc.exe和mingw32-make.exe。
在文件CMakeCache.txt中该高速缓存变量设置如下：

//C compiler
CMAKE_C_COMPILER:FILEPATH=C:/Program Files (x86)/CodeBlocks/MinGW/bin/gcc.exe

//Program used to build from makefiles.
CMAKE_MAKE_PROGRAM:STRING=nmake

我认为这个问题来自CMAKE_MAKE_PROGRAM变量，它应该取C:/Program Files (x86)/CodeBlocks/MinGW/bin/mingw32-make.exe，但是我不明白它从哪里得到nmake的值。
即使我手动更换了它，我也会遇到同样的问题。
我的疑问：

• CMake如何填充该高速缓存变量？
• 为什么CMAKE_MAKE_PROGRAM取nmake的值？
• 为什么手动更改此变量不能解决问题？