将命令行实用程序的输出传递给编译器/链接器 [英] Pass output of command line utility to compiler/linker

问题描述

我想将 getconf PAGESIZE 命令输出的结果作为预处理器定义传递给我的程序，格式为 -DPAGESIZE =`getconf PAGESIZE` 在自定义分配器声明中用于 [[gnu :: assume_aligned（PAGESIZE）] ）。

I want to pass result of the getconf PAGESIZE command output as preprocessor define to my program in form of -DPAGESIZE=`getconf PAGESIZE` for [[gnu::assume_aligned(PAGESIZE)]] in custom allocator declaration.

我尝试了以下操作：

add_definitions(-DPAGESIZE=`getconf PAGESIZE`)

但它的扩展范围完全与 -DPAGESIZE = \`getconf ... PAGESIZE` ，其中 ... 是其他 CMAKE_CXX_FLAGS * 的内容。即在 CMakeLists.txt 文件中存在转义符转义的问题。

But it expanded exactly as -DPAGESIZE="\`getconf" ... PAGESIZE`, where ... is contents of other CMAKE_CXX_FLAGS*. I.e. there is an issue with escaping of backticks in CMakeLists.txt files.

如何正确地将这样的参数传递给 CMakeLists.txt 文件中的编译器/链接器？也许还有另一种方法可以达到期望？

How to properly pass such an arguments to compiler/linker in CMakeLists.txt files? Maybe is there another way to achieve desired?

我还尝试了 add_definitions（-DPAGESIZE = $$（getconf PAGESIZE））（ $$ 由 cmake $ >），但 -DPAGESIZE 和其余部分由 cmake 分割。 add_definitions（-DPAGESIZE = $$（getconf PAGESIZE））使 cmake 避开每个美元符号。 / p>

Also I tried add_definitions(-DPAGESIZE="$$(getconf PAGESIZE)") ($$ expanded as $ by cmake), but -DPAGESIZE and the rest part are splitted by cmake. add_definitions("-DPAGESIZE=$$(getconf PAGESIZE)") makes cmake to escape every dollar sign though.

推荐答案

根据 add_definitions 命令，传递给此命令的预处理器定义将附加到 COMPILE_DEFINITIONS 属性：

According to documentation for add_definitions command, preprocessor definitions, passed to this command, are appended to COMPILE_DEFINITIONS property:

以-D或/ D开头的看起来像预处理程序定义的标志会自动添加到当前目录的COMPILE_DEFINITIONS目录属性中。

Flags beginning in -D or /D that look like preprocessor definitions are automatically added to the COMPILE_DEFINITIONS directory property for the current directory.

和 COMPILE_DEFINITIONS 属性的内容，根据其文档始终由CMake进行转义，因此您不能在构建命令中保留反引号的特殊含义：

And content of COMPILE_DEFINITIONS property, according to its documentation is always escaped by CMake, so you cannot preserve special meaning of backticks in the build command:

CMake wi ll将自动为本机构建系统正确地忽略该值

CMake will automatically escape the value correctly for the native build system

您可以手动修改CMAKE_CXX_FLAGS，如您的注释中所示。

Your may modify CMAKE_CXX_FLAGS manually, as you show in your comment.

更好的方法是在 configuration 阶段使用 execute_process 命令运行所需的命令，并使用它的输出用于 add_definitions 命令。 （或使用此输出通过 configure_file 创建其他头文件）。

The better way is to use execute_process command for run needed command at configuration stage, and use its output for add_definitions command. (Or use this output for create additional header file with configure_file).

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