如何通过 FetchContent 将 Eigen 库添加到 cmake c++ 项目

Question

通过添加特征值

FetchContent_Declare(
  eigen
  GIT_REPOSITORY https://gitlab.com/libeigen/eigen.git
  GIT_TAG        3.3.9
)

FetchContent_GetProperties(eigen)

if(NOT eigen_POPULATED)
    FetchContent_Populate(eigen)
    add_subdirectory(${eigen_SOURCE_DIR} ${eigen_BINARY_DIR})
endif()

find_package (Eigen3 3.3 REQUIRED NO_MODULE) 

给我错误

CMake Error at o/b/x64-Debug/_deps/eigen-build/Eigen3Config.cmake:20 (include):
  The file

    D:/XXX/o/b/x64-Debug/_deps/eigen-build/Eigen3Targets.cmake

  was generated by the export() command.  It may not be used as the argument
  to the include() command.  Use ALIAS targets instead to refer to targets by
  alternative names.        D:\XXX\o/b/x64-Debug/_deps/eigen-build/Eigen3Config.cmake   20

但手动下载 Eigen 并添加它效果很好

add_subdirectory("${PROJECT_SOURCE_DIR}/extern/eigen")
find_package (Eigen3 3.3 REQUIRED NO_MODULE) 

有任何想法吗 ？

Answer 1

以任意顺序：

• ALIASEigen 仅在主参考上提供目标
  ：https://gitlab.com/libeigen/eigen/-/commit/cf0b5b0344a3bfcf410e95bf22289015a2daf34b#9a2aa4db38d3115ed60da621e012c0efc0172aae_671_599

• FetchContent 用法可以是

message(CHECK_START "Fetching Eigen3")
list(APPEND CMAKE_MESSAGE_INDENT "  ")

include(FetchContent)
FetchContent_Declare(
  Eigen
  GIT_REPOSITORY https://gitlab.com/libeigen/eigen.git
  GIT_TAG master
  GIT_SHALLOW TRUE
  GIT_PROGRESS TRUE)
# note: To disable eigen tests,
# you should put this code in a add_subdirectory to avoid to change
# BUILD_TESTING for your own project too since variables are directory
# scoped
set(BUILD_TESTING OFF)
set(EIGEN_BUILD_TESTING OFF)
set(EIGEN_MPL2_ONLY ON)
set(EIGEN_BUILD_PKGCONFIG OFF)
set(EIGEN_BUILD_DOC OFF)
FetchContent_MakeAvailable(Eigen)

list(POP_BACK CMAKE_MESSAGE_INDENT)
message(CHECK_PASS "fetched")
...
target_link_libraries(YourTarget PRIVATE Eigen3::Eigen)

• 请find_package()参阅https://gitlab.kitware.com/cmake/cmake/-/issues/17735 编辑：现在您也可以在 参考中使用： https FetchContent()/add_subdirectory(): //cmake.org/cmake/help/latest/module/FetchContent .html#integrating-with-find-package
  FIND_PACKAGE_ARGS NAMES Eigen3Fetchcontent_Declare()