How to set(SHIELD "<shield>") in app CMakeLists.txt only for a specific board?

[cdwilson]

I have an app that needs to set(SHIELD "arduino_uno_click") in CMakeLists.txt but ONLY for the nRF9160 DK board (other boards supported by this app do not need this shield enabled).

I tried the following but it does not work:

cmake_minimum_required(VERSION 3.20.0)

if(CONFIG_BOARD_NRF9160DK_NRF9160 OR CONFIG_BOARD_NRF9160DK_NRF9160_NS)
  set(SHIELD "arduino_uno_click")
endif()

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})

...

[cdwilson]

This works correctly:

cmake_minimum_required(VERSION 3.20.0)

if((BOARD STREQUAL nrf9160dk_nrf9160) OR (BOARD STREQUAL nrf9160dk_nrf9160_ns))
  set(SHIELD "arduino_uno_click")
endif()

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})

...

(At this point, I don't understand why the first thing I tried doesn't work. If anyone knows, I'd appreciate the explanation!)