如何从cmake目标自动生成pkgconfig文件

Question

我想从目标生成cmake中的pkgconfig文件.我盯着写下这样的东西:

function(auto_pkgconfig TARGET)

    get_target_property(INCLUDE_DIRS ${TARGET} INTERFACE_INCLUDE_DIRECTORIES)
    string(REPLACE "$<BUILD_INTERFACE:" "$<0:" INCLUDE_DIRS "${INCLUDE_DIRS}")
    string(REPLACE "$<INSTALL_INTERFACE:" "$<1:" INCLUDE_DIRS "${INCLUDE_DIRS}")
    string(REPLACE "$<INSTALL_PREFIX>" "${CMAKE_INSTALL_PREFIX}" INCLUDE_DIRS "${INCLUDE_DIRS}")


    file(GENERATE OUTPUT ${TARGET}.pc CONTENT "
Name: ${TARGET}
Cflags: -I$<JOIN:${INCLUDE_DIRS}, -I>
Libs: -L${CMAKE_INSTALL_PREFIX}/lib -l${TARGET}
")
    install(FILES ${TARGET}.pc DESTINATION lib/pkgconfig)
endfunction()

这是一个简化版本,但它基本上读取INTERFACE_INCLUDE_DIRECTORIES属性并处理INSTALL_INTERFACE生成器表达式.只要在调用之前设置了include目录,这样就可以正常工作auto_pkgconfig,如下所示:

add_library(foo foo.cpp)

target_include_directories(foo PUBLIC 
    $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/include>
    $<INSTALL_INTERFACE:$<INSTALL_PREFIX>/include>
    ${OTHER_INCLUDE_DIRS}
)

auto_pkgconfig(foo)

但是,有时会在调用之后设置属性auto_pkgconfig,如下所示:

add_library(foo foo.cpp)
auto_pkgconfig(foo)

target_include_directories(foo PUBLIC 
    $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/include>
    $<INSTALL_INTERFACE:$<INSTALL_PREFIX>/include>
    ${OTHER_INCLUDE_DIRS}
)

但是,这将无法正确读取包含目录.我希望auto_pkgconfig在设置所有目标属性后运行.我可以使用生成器表达式,通过更改auto_pkgconfig为:

function(auto_pkgconfig TARGET)

    file(GENERATE OUTPUT ${TARGET}.pc CONTENT "
Name: ${TARGET}
Cflags: -I$<JOIN:$<TARGET_PROPERTY:${TARGET},INTERFACE_INCLUDE_DIRECTORIES>, -I>
Libs: -L$<TARGET_FILE_DIR:${TARGET}> -l${TARGET}
")
    install(FILES ${TARGET}.pc DESTINATION lib/pkgconfig)
endfunction() 

但是,这将读取BUILD_INTERFACE而不是INSTALL_INTERFACE.那么有没有另一种方法来设置它们之后读取目标属性？

Answer 1

根据CMake 文档， 的内容INSTALL_INTERFACE仅在调用时可用install(EXPORT)。除非他们扩展 CMake，否则最好执行其他操作来生成 PkgConfig 文件。理想情况下，您对安装布局有足够的控制权，以使这一切变得容易。

然而，这并不意味着你不能按照你的要求去做；这只是“小马托尼”级别的邪恶。其实我很犹豫要不要发这个。请不要将此视为建议。

这个想法是使用install(EXPORT)CMake 生成适当的脚本。然后生成一个使用您上面给出的代码的虚拟 CMake 项目file(GENERATE OUTPUT ...)；虚拟项目将看到导出的，即。INSTALL_INTERFACE特性。

我最初尝试使用install(CODE [[ ... ]])这样做，但它也看到了$<BUILD_INTERFACE:...>视图。我在CMake Discourse上询问过这个问题。

cmake_minimum_required(VERSION 3.16)
project(example)

# Dummy library for demo

add_library(example SHARED example.cpp)

target_compile_definitions(example
  PUBLIC $<BUILD_INTERFACE:BUILD>
         $<INSTALL_INTERFACE:INSTALL>)

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

# Here be dragons...

function(auto_pc TARGET)
  file(CONFIGURE OUTPUT "pc.${TARGET}/CMakeLists.txt"
       CONTENT [[
cmake_minimum_required(VERSION 3.16)
project(pc_@TARGET@)

find_package(pc_@TARGET@ REQUIRED CONFIG)

file(GENERATE OUTPUT @TARGET@.pc
     CONTENT [=[
Name: @TARGET@
Cflags: -I$<JOIN:$<TARGET_PROPERTY:INTERFACE_INCLUDE_DIRECTORIES>, -I> -D$<JOIN:$<TARGET_PROPERTY:INTERFACE_COMPILE_DEFINITIONS>, -D>
Libs: -L$<TARGET_FILE_DIR:@TARGET@> -l@TARGET@
]=]   TARGET "@TARGET@")
]] @ONLY NEWLINE_STYLE LF)

  install(TARGETS ${TARGET} EXPORT pc_${TARGET})
  install(EXPORT pc_${TARGET} DESTINATION "_auto_pc" FILE pc_${TARGET}-config.cmake)

  file(CONFIGURE OUTPUT "pc.${TARGET}/post-install.cmake"
       CONTENT [[
file(REAL_PATH "${CMAKE_INSTALL_PREFIX}" prefix)
set(proj "@CMAKE_CURRENT_BINARY_DIR@/pc.@TARGET@")
execute_process(COMMAND "@CMAKE_COMMAND@" "-Dpc_@TARGET@_DIR=${prefix}/_auto_pc" -S "${proj}" -B "${proj}/build")
file(COPY "${proj}/build/@TARGET@.pc" DESTINATION "${prefix}")
]] @ONLY NEWLINE_STYLE LF)

  install(SCRIPT "${CMAKE_CURRENT_BINARY_DIR}/pc.${TARGET}/post-install.cmake")
endfunction()

auto_pc(example)

# Clean up install path
install(CODE [[ file(REMOVE_RECURSE "${CMAKE_INSTALL_PREFIX}/_auto_pc") ]])

结果如下：

alex@Alex-Desktop:~/test$ cmake -S . -B build
...
-- Configuring done
-- Generating done
-- Build files have been written to: /home/alex/test/build
alex@Alex-Desktop:~/test$ cmake --build build/
...
alex@Alex-Desktop:~/test$ cmake --install build --prefix install
-- Install configuration: ""
-- Installing: /home/alex/test/install/lib/libexample.so
-- Installing: /home/alex/test/install/_auto_pc/pc_example-config.cmake
-- Installing: /home/alex/test/install/_auto_pc/pc_example-config-noconfig.cmake
-- The C compiler identification is GNU 9.3.0
-- The CXX compiler identification is GNU 9.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/alex/test/build/pc.example/build
alex@Alex-Desktop:~/test$ ls install/
example.pc  lib
alex@Alex-Desktop:~/test$ cat install/example.pc
Name: example
Cflags: -I/home/alex/test/install/include -DINSTALL
Libs: -L/home/alex/test/install/lib -lexample

这应该让你感到悲伤。这让我很难过。