如何使用CMake通过命令行定义C ++预处理器宏？ [英] How to define a C++ preprocessor macro through the command line with CMake?

问题描述

我尝试在CMake的命令行中设置预处理器宏。我尝试过：

I try to set a preprocessor macro in the command line of CMake. I've tried:

set generator="Visual Studio 8 2005"
set params=-D MY_MACRO=1
cmake.exe -G %generator% %params% ..\some_project

但是它在编译时既没有定义，也没有在CMake生成的文件中找到名称 MY_MACRO ，除了 CMakeCache.txt 的形式：

but it's neither defined when I compile nor can I find the name MY_MACRO in the files generated by CMake at all, except for CMakeCache.txt where it's present in the form:

MY_MACRO:UNINITIALIZED=1

我该怎么办？

推荐答案

问题背后的动机是批量构建第三方库，这就是为什么我要避免修改CMakeLists的原因。这么多年后，即使我不再需要它了，我也发现可以通过 CMake外部的手段轻松实现：

The motivation behind the question was to batch build 3rd party libraries, which is why I wanted to avoid modifying CMakeLists. So years later, even though I don't need that anymore, I figured out that it's easily achievable by means external to CMake:

• 照常调用CMake，没有特殊标志。

• Invoke CMake as usual, no special flags.

然后：

• 使用MSVC：编译器读取 CL 环境变量以获取额外的命令行参数。因此

• With MSVC: The compiler reads the CL environment variable to get extra command line arguments. So

set CL=/DMY_MACRO=1 %CL%

然后调用MSBuild来完成其工作。

then invoke MSBuild to do its job.

与其他工具链：通过在调用 make之前设置 CFLAGS 或 CXXFLAGS 环境变量可能是可行的code>，但我没有检查。

With other toolchains: It might be doable by setting CFLAGS or CXXFLAGS environment variables prior to calling make, but I didn't check that.

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