C++ 从命令行调用时将包含目录添加到 CMake
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Adding include directories to CMake when calling it from the command line
提问by Ayberk ?zgür
I'm in a situation where I should not disturb the existing CMakeLists.txt files, but I still should add some g++ system include directory to my build.
我不应该打扰现有的 CMakeLists.txt 文件，但我仍然应该在我的构建中添加一些 g++ 系统包含目录。
In other words, I need -isystem /path/to/my/includeadded to my compiler flags, but when calling something like cmake ...
换句话说，我需要-isystem /path/to/my/include添加到我的编译器标志中，但是当调用类似cmake ...
Maybe something like cmake .. -DCMAKE_CXX_FLAGS="$CMAKE_CXX_FLAGS -isystem /path/to/my/include"? Is there a way to do this?
也许像cmake .. -DCMAKE_CXX_FLAGS="$CMAKE_CXX_FLAGS -isystem /path/to/my/include"？有没有办法做到这一点？
采纳答案by avtomaton
I have the same problem. I found two solutions:
我也有同样的问题。我找到了两个解决方案：
The one proposed by sakra in a previous answer, i.e. setting an environment variable with C++ flags:
export CXXFLAGS=-isystem\ /path/to/my/include cmake <path to my sources>ORthe same thing, but environment variable are set only for this CMakecall:
CXXFLAGS=-isystem\ /path/to/my/include cmake <path to my sources>IMPORTANT: you mustclean your build directory (i.e. clean the CMake cache) before launching any of this form. Without cleaning the cache, CMake will continue using your cached
CMAKE_CXX_FLAGSfrom the previous run.Directly setting
CMAKE_CXX_FLAGSin cmake string:cmake -DCMAKE_CXX_FLAGS=-isystem\ /path/to/my/include <path to my sources>
该在前面的回答沙克拉通过提出一个，即设置与C ++标志的环境变量：
export CXXFLAGS=-isystem\ /path/to/my/include cmake <path to my sources>或同样的事情，但环境变量仅为此CMake调用设置：
CXXFLAGS=-isystem\ /path/to/my/include cmake <path to my sources>重要提示：在启动任何此表单之前，您必须清理构建目录（即清理 CMake 缓存）。在不清理缓存的情况下，CMake 将继续使用您
CMAKE_CXX_FLAGS之前运行的缓存。直接
CMAKE_CXX_FLAGS在 cmake 字符串中设置：cmake -DCMAKE_CXX_FLAGS=-isystem\ /path/to/my/include <path to my sources>
I believe that it can be done by a more 'native' way, but I didn't find a variable responsible for paths to headers in CMake.
我相信它可以通过更“本机”的方式完成，但我没有找到负责 CMake 中标头路径的变量。
回答by sakra
You can set the environment variable CXXFLAGSbefore invoking CMake.
您可以CXXFLAGS在调用 CMake 之前设置环境变量。
$ export CXXFLAGS=-isystem\ /path/to/my/include
$ cmake ..
CMake will the initialize the cache variable CMAKE_CXX_FLAGSwith the flags from the environment variable. The variable affects all build types.
CMake 将CMAKE_CXX_FLAGS使用环境变量中的标志初始化缓存变量。该变量影响所有构建类型。
回答by scrutari
Using -DCMAKE_CXX_STANDARD_INCLUDE_DIRECTORIES=<something>worked for me even without toolchain file. This avoids cluttering compiler flags.
-DCMAKE_CXX_STANDARD_INCLUDE_DIRECTORIES=<something>即使没有工具链文件，使用也对我有用。这避免了混乱的编译器标志。
回答by rmbianchi
Just an additional note to the other answers: with CMake 3.15.3on macOS 10.14.5, only the solution using the CMake flag seems to work properly.
只是对其他答案的补充说明：对于macOS 10.14.5上的CMake 3.15.3，只有使用 CMake 标志的解决方案似乎可以正常工作。
So, in my case, only this solution worked fine:
所以，就我而言，只有这个解决方案工作正常：
cmake -DCMAKE_CXX_FLAGS=-I\ /path/to/include <path/to/source>
