cmake - 尽管设置了CC和CXX变量，但C编译器的标识是未知的

Question

我正在使用以下命令:

    cmake CC="C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\cl.exe" 
CXX="C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\cl.exe"  -G "Visual Studio 12
 Win64" -DBOOST_ROOT="c:\local\boost_1_56_0" -DBOOST_LIBRARYDIR="c:\local\boost_1_56_0\lib64-
msvc-12.0"  ..

它说:

The C compiler identification is unknown

和

The CXX compiler identification is unknown

当我在那里设置这些变量时，怎么可能？

编辑:错误日志文件:

Compiling the C compiler identification source file "CMakeCCompilerId.c" failed.
Compiler:  
Build flags: 
Id flags: 

The output was:
1
Microsoft (R) Build Engine version 12.0.30723.0
[Microsoft .NET Framework, version 4.0.30319.18444]
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 21-09-2014 20:17:49.
Project "D:\foo\build\CMakeFiles\3.0.2\CompilerIdC\CompilerIdC.vcxproj" on node 1 (default targets).
PrepareForBuild:
  Creating directory "Debug\".
  Creating directory "Debug\CompilerIdC.tlog\".
InitializeBuildStatus:
  Creating "Debug\CompilerIdC.tlog\unsuccessfulbuild" because "AlwaysCreate" was specified.
ClCompile:
  C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\x86_amd64\CL.exe /c /nologo /W0 /WX- /Od /D _MBCS /Gm- /EHsc /RTC1 /MDd /GS /fp:precise /Zc:wchar_t /Zc:forScope /Fo"Debug\\" /Fd"Debug\vc120.pdb" /Gd /TC /errorReport:queue CMakeCCompilerId.c
  CMakeCCompilerId.c
Link:
  C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\x86_amd64\link.exe /ERRORREPORT:QUEUE /OUT:".\CompilerIdC.exe" /INCREMENTAL:NO /NOLOGO kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /MANIFEST /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /manifest:embed /PDB:".\CompilerIdC.pdb" /SUBSYSTEM:CONSOLE /TLBID:1 /DYNAMICBASE /NXCOMPAT /IMPLIB:".\CompilerIdC.lib" /MACHINE:X64 Debug\CMakeCCompilerId.obj
LINK : fatal error LNK1181: cannot open input file 'gdi32.lib' [D:\foo\build\CMakeFiles\3.0.2\CompilerIdC\CompilerIdC.vcxproj]
Done Building Project "D:\foo\build\CMakeFiles\3.0.2\CompilerIdC\CompilerIdC.vcxproj" (default targets) -- FAILED.

Build FAILED.

"D:\foo\build\CMakeFiles\3.0.2\CompilerIdC\CompilerIdC.vcxproj" (default target) (1) ->
(Link target) -> 
  LINK : fatal error LNK1181: cannot open input file 'gdi32.lib' [D:\foo\build\CMakeFiles\3.0.2\CompilerIdC\CompilerIdC.vcxproj]

    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:00.47


Compiling the CXX compiler identification source file "CMakeCXXCompilerId.cpp" failed.
Compiler:  
Build flags: 
Id flags: 

The output was:
1
Microsoft (R) Build Engine version 12.0.30723.0
[Microsoft .NET Framework, version 4.0.30319.18444]
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 21-09-2014 20:17:50.
Project "D:\foo\build\CMakeFiles\3.0.2\CompilerIdCXX\CompilerIdCXX.vcxproj" on node 1 (default targets).
PrepareForBuild:
  Creating directory "Debug\".
  Creating directory "Debug\CompilerIdCXX.tlog\".
InitializeBuildStatus:
  Creating "Debug\CompilerIdCXX.tlog\unsuccessfulbuild" because "AlwaysCreate" was specified.
ClCompile:
  C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\x86_amd64\CL.exe /c /nologo /W0 /WX- /Od /D _MBCS /Gm- /EHsc /RTC1 /MDd /GS /fp:precise /Zc:wchar_t /Zc:forScope /Fo"Debug\\" /Fd"Debug\vc120.pdb" /Gd /TP /errorReport:queue CMakeCXXCompilerId.cpp
  CMakeCXXCompilerId.cpp
Link:
  C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\x86_amd64\link.exe /ERRORREPORT:QUEUE /OUT:".\CompilerIdCXX.exe" /INCREMENTAL:NO /NOLOGO kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /MANIFEST /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /manifest:embed /PDB:".\CompilerIdCXX.pdb" /SUBSYSTEM:CONSOLE /TLBID:1 /DYNAMICBASE /NXCOMPAT /IMPLIB:".\CompilerIdCXX.lib" /MACHINE:X64 Debug\CMakeCXXCompilerId.obj
LINK : fatal error LNK1181: cannot open input file 'gdi32.lib' [D:\foo\build\CMakeFiles\3.0.2\CompilerIdCXX\CompilerIdCXX.vcxproj]
Done Building Project "D:\foo\build\CMakeFiles\3.0.2\CompilerIdCXX\CompilerIdCXX.vcxproj" (default targets) -- FAILED.

Build FAILED.

"D:\foo\build\CMakeFiles\3.0.2\CompilerIdCXX\CompilerIdCXX.vcxproj" (default target) (1) ->
(Link target) -> 
  LINK : fatal error LNK1181: cannot open input file 'gdi32.lib' [D:\foo\build\CMakeFiles\3.0.2\CompilerIdCXX\CompilerIdCXX.vcxproj]

    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:00.50

Answer 1

可以使用CC和CXX变量来选择编译器，但是比使用-G(generator)参数要复杂得多。例如，路径中的斜线必须是Unix样式(/)，并且在第一次运行CMake配置之后，除非清除了缓存，否则它们不会生效。

有关可用的生成器选项的列表，请包括--help选项

Boost库的路径还必须使用Unix样式斜杠(/)。许多命令将转换Windows路径，但是在命令行中传递定义时，您将希望始终使用Unix样式路径。

您的命令将更改为以下内容:

cmake -G "Visual Studio 12 2013 Win64" -DBOOST_ROOT="C:/local/boost_1_56_0" -DBOOST_LIBRARYDIR="C:/local/boost_1_56_0/lib64-msvc-12.0" ..

您还需要确保为Visual Studio和x64正确设置了PATH环境变量。通过使用以下命令打开VS2013 x64 native 工具命令提示符，可以轻松完成此操作:

cmd /k "%VS120CoMNTOOLS%\..\..\VC\vcvarsall.bat" amd64

另外，在尝试之前，请确保已清除cmake缓存。最简单的方法是删除cmake构建文件夹，但是您也可以使用CMake-gui清除缓存。