[BUG] Doesn't compile due to errors with spdlog

[eezstreet]

I'm attempting to build ArrayFire from source, and I'm stuck due to an issue with spdlog.

I have the latest version of spdlog that is present in my system:

libspdlog-dev/focal,now 1:1.5.0-1 arm64 [installed]
  Very fast, header only or compiled, C++ logging library

libspdlog1/focal,now 1:1.5.0-1 arm64 [installed,automatic]
  Very fast C++ logging library

And when trying to generate the makefiles for ArrayFire (using CMake), I get the following error:

CMake Error at CMakeLists.txt:264 (add_library):
  add_library cannot create ALIAS target "af_spdlog" because target
  "spdlog::spdlog" is imported but not globally visible.

If I change the following line in CMakeLists.txt from this:

if(TARGET spdlog::spdlog OR AF_WITH_EXTERNAL_PACKAGES_ONLY)

to this:

if(NOT TARGET spdlog::spdlog OR AF_WITH_EXTERNAL_PACKAGES_ONLY)

I can get it to work. However, this is not ideal.

Reproducible Code and/or Steps

I did the following:

mkdir build && cd build && cmake ..

System Information

1. ArrayFire version: latest on master
2. Devices installed on system: It's an Orin DevKit.
3. Output from af::info(): N/A, it doesn't compile.
4. Output from scripts:

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.6 LTS
Release:        20.04
Codename:       focal
nvidia-smi not found
rocm-smi not found.
clinfo not found.

(note: nvidia-smi is not available due to this being a Jetson device.)

Checklist

• Using the latest available ArrayFire release
• GPU drivers are up to date