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Bug 4419

Summary: Undefined symbols for SDL_COREMOTION_SensorDriver on iOS using CMake
Product: SDL Reporter: Steve Robinson <ssrobins>
Component: buildAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: 2.0.9   
Hardware: iPhone/iPod touch   
OS: macOS 10.13   

Description Steve Robinson 2018-12-10 00:37:15 UTC 
When building SDL2 2.0.9 on iOS with a CMake-generated Xcode project, I get this linker error:

Undefined symbols for architecture armv7:
  "_SDL_COREMOTION_SensorDriver", referenced from:
      _SDL_SensorInit in libSDL2.a(SDL_sensor.o)
      _SDL_SensorQuit in libSDL2.a(SDL_sensor.o)
      _SDL_SensorUpdate in libSDL2.a(SDL_sensor.o)
ld: symbol(s) not found for architecture armv7

Full build output:
https://gitlab.com/ssrobins/sdl2-example/-/jobs/132014142

To fix it, I replaced the following in the CMakeLists.txt file:
if(SDL_SENSOR)
  file(GLOB SENSOR_SOURCES ${SDL2_SOURCE_DIR}/src/sensor/*.c)
  set(SOURCE_FILES ${SOURCE_FILES} ${SENSOR_SOURCES})
endif()

With this:
if(SDL_SENSOR)
  file(GLOB SENSOR_SOURCES ${SDL2_SOURCE_DIR}/src/sensor/*.c)
  if(IOS)
    file(GLOB EXTRA_SENSOR_SOURCES ${SDL2_SOURCE_DIR}/src/coremotion/*.m)
  endif()
  set(SOURCE_FILES ${SOURCE_FILES} ${SENSOR_SOURCES} ${EXTRA_SENSOR_SOURCES})
endif()

Commit:
https://gitlab.com/ssrobins/conan-sdl2/commit/020262ad603471a32aac24b8d48202003d55691e
I also employed the build changes described here https://bugzilla.libsdl.org/show_bug.cgi?id=4178, which you can see in the referenced commit above.
Comment 1 Steve Robinson 2020-04-06 04:46:50 UTC 
It's fixed in SDL 2.0.12. Thanks!