cmake 中 BUILD_INTERFACE

在CMake中，BUILD_INTERFACE是用于指定构建接口的关键字。它用于指定在构建目标时所使用的头文件和链接库等接口文件。

当使用BUILD_INTERFACE关键字时，CMake会将相关的头文件和链接库（INTERFACE_INCLUDE_DIRECTORIES、INTERFACE_LINK_LIBRARIES等）添加到构建目标的接口属性中。这意味着这些接口文件只在构建目标时可用，而不会被导出到安装目录中。

在实际使用中，你可以通过设置BUILD_INTERFACE来避免将接口文件安装到目标文件夹，从而提供更好的封装和隔离性。这对于库的开发者来说尤为重要，因为它们可以控制哪些文件在使用他们的库时可见。

相关问题

cmake BUILD_INTERFACE

CMake's `BUILD_INTERFACE` is a generator expression that is used to specify build-time dependencies or paths. It allows you to control the behavior of targets during the build process.

When using `BUILD_INTERFACE`, you can specify paths or include directories that are only relevant during the build phase of your project. These paths or directories will not be propagated to consuming projects when they link against your target.

For example, if you have a library target and you want to include some header files only during the build process, you can use `BUILD_INTERFACE` in conjunction with `target_include_directories()`. This ensures that the headers are only included when building your target, but not when using your library as a dependency.

Here's an example:

target_include_directories(my_library
    PUBLIC
        $<INSTALL_INTERFACE:include>
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
)

In this example, `${CMAKE_CURRENT_SOURCE_DIR}/include` is included only during the build process, while `include` is included when using the installed library.

Note that `BUILD_INTERFACE` is evaluated during the configuration step, so any paths or dependencies specified with it should be available at configure time.

cmake_minimum_required(VERSION 3.16) # 声明该项目的名称和版本号 project(MyLib VERSION 1.0) # 添加库代码文件到该库 add_library(mylib STATIC src/header.cpp) target_include_directories(mylib INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include> ) add_library(mylib_shared SHARED src/header.cpp) target_include_directories(mylib_shared INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include> ) # include_directories(include) # 指定install路径，以便于其他项目找到该库 install(TARGETS mylib mylib_shared EXPORT MyLibTargets ARCHIVE DESTINATION lib LIBRARY DESTINATION lib RUNTIME DESTINATION bin) install(FILES include/header.h DESTINATION include) # 生成MyLibConfig.cmake文件 include(CMakePackageConfigHelpers) write_basic_package_version_file( "${CMAKE_CURRENT_BINARY_DIR}/MyLibConfigVersion.cmake" VERSION ${MyLib_VERSION} COMPATIBILITY AnyNewerVersion ) configure_package_config_file( "${CMAKE_CURRENT_SOURCE_DIR}/MyLibConfig.cmake.in" "${CMAKE_CURRENT_BINARY_DIR}/MyLibConfig.cmake" INSTALL_DESTINATION cmake ) install( EXPORT MyLibTargets NAMESPACE MyLib:: DESTINATION cmake ) # export(EXPORT MyLibTargets # NAMESPACE MyLib:: # FILE MyLibTargets.cmake) # install(FILES ${CMAKE_CURRENT_BINARY_DIR}/MyLibTargets.cmake DESTINATION cmake) install( FILES "${CMAKE_CURRENT_BINARY_DIR}/MyLibConfig.cmake" "${CMAKE_CURRENT_BINARY_DIR}/MyLibConfigVersion.cmake" DESTINATION cmake )为什么执行时，提醒/home/czl/cmake_lib/src/header.cpp:1:10: fatal error: header.h: 没有那个文件或目录

在你的 `CMakeLists.txt` 文件中，你已经将 `include/header.h` 安装到了 `include` 目录中，但是在 `add_library` 命令中没有将该目录添加到编译器的 include 路径中，所以编译器无法找到该头文件。

你可以将 `target_include_directories` 命令添加到 `add_library` 命令中，这样就可以将 `include` 目录添加到编译器的 include 路径中了。修改后的代码如下所示：

cmake_minimum_required(VERSION 3.16)
project(MyLib VERSION 1.0)

# 添加库代码文件到该库
add_library(mylib STATIC src/header.cpp)
target_include_directories(mylib 
    PUBLIC
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
        $<INSTALL_INTERFACE:include>
)

add_library(mylib_shared SHARED src/header.cpp)
target_include_directories(mylib_shared 
    PUBLIC
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
        $<INSTALL_INTERFACE:include>
)

# 指定install路径，以便于其他项目找到该库
install(TARGETS mylib mylib_shared
        EXPORT MyLibTargets
        ARCHIVE DESTINATION lib
        LIBRARY DESTINATION lib
        RUNTIME DESTINATION bin)

install(FILES include/header.h DESTINATION include)

# 生成MyLibConfig.cmake文件
include(CMakePackageConfigHelpers)
write_basic_package_version_file(
    "${CMAKE_CURRENT_BINARY_DIR}/MyLibConfigVersion.cmake"
    VERSION ${MyLib_VERSION}
    COMPATIBILITY AnyNewerVersion
)

configure_package_config_file(
    "${CMAKE_CURRENT_SOURCE_DIR}/MyLibConfig.cmake.in"
    "${CMAKE_CURRENT_BINARY_DIR}/MyLibConfig.cmake"
    INSTALL_DESTINATION cmake
)

install(
    EXPORT MyLibTargets
    NAMESPACE MyLib::
    DESTINATION cmake
)

install(
    FILES
        "${CMAKE_CURRENT_BINARY_DIR}/MyLibConfig.cmake"
        "${CMAKE_CURRENT_BINARY_DIR}/MyLibConfigVersion.cmake"
    DESTINATION cmake
)

注意，在这里，我们使用了 `PUBLIC` 修饰符，将 include 路径添加到了 `mylib` 和 `mylib_shared` 目标的 include 路径中，这样在编译 `mylib` 和 `mylib_shared` 时都可以找到 `include/header.h` 头文件。