How to integrate xtensor-blas in cmake by using fetch_content

[Roy-Kid]

Hi everyone,

I try to use cmake to manage my all dependencies. Here is the code I want it to download xtensor and related packages automatically if find_package is failed:

# define target
file(GLOB_RECURSE MOLCORE_SRC "./*.cpp")
add_library(
    molcore_molcore
    ${MOLCORE_SRC}
)

# introduce deps
find_package(xtl QUIET)
find_package(xtensor QUIET)
find_package(xtensor-blas QUIET)

if(NOT xtl_FOUND)
  message("downloading xtl source...")
  FetchContent_Declare(
    xtl
    GIT_REPOSITORY https://github.com/xtensor-stack/xtl.git
    GIT_TAG        master
  )
  FetchContent_MakeAvailable(xtl)
else()
  message("found xtl ${xtl_VERSION}")
endif()
if(NOT xtensor_FOUND)
  message("downloading xtensor source...")
  FetchContent_Declare(
    xtensor
    GIT_REPOSITORY https://github.com/xtensor-stack/xtensor.git
    GIT_TAG        master
    FIND_PACKAGE_ARGS NAMES xtensor
  )
  FetchContent_MakeAvailable(xtensor)
  target_include_directories(molcore_molcore PUBLIC "$<BUILD_INTERFACE:${xtensor_SOURCE_DIR}/include>" "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
else()
  message("found xtensor ${xtensor_VERSION}")
  target_include_directories(molcore_molcore PUBLIC ${xtensor_INCLUDE_DIRS})
endif()
if(NOT xtensor-blas_FOUND)
  message("downloading xtensor-blas source...")
  FetchContent_Declare(
    xtensor-blas
    GIT_REPOSITORY https://github.com/xtensor-stack/xtensor-blas.git
    GIT_TAG        master
    FIND_PACKAGE_ARGS NAMES xtensor
  )
  FetchContent_MakeAvailable(xtensor-blas)
else()
  message("found xtensor-blas ${xtensor-blas_VERSION}")
endif()

It seems xtensor is found, but still error raises:

found xtl 0.7.2
found xtensor 0.23.10
downloading xtensor-blas source...
-- The C compiler identification is GNU 11.4.0
-- 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
-- xtensor-blas v0.21.0
CMake Error (dev) at build/dev/_deps/xtensor-blas-src/CMakeLists.txt:49 (set):
  uninitialized variable 'XTENSOR_VERSION_MAJOR'
This error is for project developers. Use -Wno-error=dev to suppress it.

Can you give a receipt about integrating xtensor using cmake instead of conda? I also tried spack, but it was also a little difficult to get a head-only file.