如何让CMake通过Makefile生成预处理C文件时使用-dD和-dI选项？

问题场景 #

在Windows 10的MINGW64（MSYS2）bash环境下，采用MSYS Makefiles构建CMake项目时，默认生成的C源文件预处理目标（如main.c.i）仅使用-g、-std=gnu11和-E选项执行GCC预处理，无法保留宏定义与包含指令信息。需要修改CMakeLists.txt，让预处理命令自动加入-dD和-dI选项。

现有示例CMakeLists.txt代码：

cmake_minimum_required(VERSION 3.13)

if (NOT(EXISTS "${CMAKE_SOURCE_DIR}/main.c" AND NOT IS_DIRECTORY "${CMAKE_SOURCE_DIR}/main.c"))
  message("${Cyan}Creating ${CMAKE_SOURCE_DIR}/main.c${ColourReset}")
  FILE(WRITE ${CMAKE_SOURCE_DIR}/main.c
    "#include <stdio.h>\n"
    "#define MYDEFINE 1\n"
    "\n"
    "int main() {\n"
    "  printf(\"Hello from mytest main .exe (MYDEFINE: %d)!\\n\", MYDEFINE);\n"
    "  return 0;\n"
    "}\n"
  )
endif()

project(mytest C)
set(CMAKE_C_STANDARD 11)
set(${PROJECT_NAME}_sources
    main.c
)

add_executable(${PROJECT_NAME} ${${PROJECT_NAME}_sources})

解决方案 #

通过设置CMAKE_C_PREPROCESSOR_FLAGS变量，可专门为C语言预处理阶段添加指定选项。在CMakeLists.txt的project指令之后添加以下配置：

# 为C语言预处理目标添加-dD和-dI选项，保留宏定义与包含指令
set(CMAKE_C_PREPROCESSOR_FLAGS "${CMAKE_C_PREPROCESSOR_FLAGS} -dD -dI")

修改后的完整CMakeLists.txt：

cmake_minimum_required(VERSION 3.13)

if (NOT(EXISTS "${CMAKE_SOURCE_DIR}/main.c" AND NOT IS_DIRECTORY "${CMAKE_SOURCE_DIR}/main.c"))
  message("${Cyan}Creating ${CMAKE_SOURCE_DIR}/main.c${ColourReset}")
  FILE(WRITE ${CMAKE_SOURCE_DIR}/main.c
    "#include <stdio.h>\n"
    "#define MYDEFINE 1\n"
    "\n"
    "int main() {\n"
    "  printf(\"Hello from mytest main .exe (MYDEFINE: %d)!\\n\", MYDEFINE);\n"
    "  return 0;\n"
    "}\n"
  )
endif()

project(mytest C)
# 新增：为预处理目标添加-dD和-dI选项
set(CMAKE_C_PREPROCESSOR_FLAGS "${CMAKE_C_PREPROCESSOR_FLAGS} -dD -dI")
set(CMAKE_C_STANDARD 11)
set(${PROJECT_NAME}_sources
    main.c
)

add_executable(${PROJECT_NAME} ${${PROJECT_NAME}_sources})

验证步骤 #

1. 清理原有构建目录：rm -rf build
2. 重新构建项目：mkdir build && cd build && cmake ../ -DCMAKE_BUILD_TYPE=Debug -G "MSYS Makefiles"
3. 执行预处理目标并查看命令：make VERBOSE=1 main.c.i

此时GCC命令行会包含-dD和-dI选项，生成的main.c.i文件会保留宏定义和包含指令信息。

内容的提问来源于stack exchange，提问作者sdbbs