sdk_resources.h does not compile with c++ in SDK12. The _cplusplus guard only begins if ESB_PRESENT is defined. The guard should either be moved above or below
#ifdef ESB_PRESENT
#include "nrf_esb_resources.h"
#ifdef __cplusplus
extern "C" {
#endif
#else
#define ESB_PPI_CHANNELS_USED 0uL /**< PPI channels utilized by ESB (not available to th spplication). */
#define ESB_TIMERS_USED 0uL /**< Timers used by ESB. */
#define ESB_SWI_USED 0uL /**< Software interrupts used by ESB */
#endif
#define NRF_PPI_CHANNELS_USED (SD_PPI_CHANNELS_USED | GZLL_PPI_CHANNELS_USED | ESB_PPI_CHANNELS_USED)
#define NRF_PPI_GROUPS_USED (SD_PPI_GROUPS_USED)
#define NRF_SWI_USED (SD_SWI_USED | GZLL_SWI_USED | ESB_SWI_USED)
#define NRF_TIMERS_USED (SD_TIMERS_USED | GZLL_TIMERS_USED | ESB_TIMERS_USED)
#ifdef __cplusplus
}
#endif
#endif // APP_RESOURCES_H__
