C++ and SDK

[nick_haman]

I am migrating my project to C++.  Everything in the SDK works so far except NRF_BLE_GATT_DEF().  This returns the error C++ requires a type specifier for all declarations.  Is there a workaround?

[nick_haman]

Another error occurs in the APP_USBD_CDC_ACM_GLOBAL_DEF:

static void cdc_acm_user_ev_handler(app_usbd_class_inst_t const * p_inst, app_usbd_cdc_acm_user_event_t event);

/**
 * @brief CDC_ACM class instance
 * */
APP_USBD_CDC_ACM_GLOBAL_DEF(m_app_cdc_acm,
	cdc_acm_user_ev_handler,
	CDC_ACM_COMM_INTERFACE,
	CDC_ACM_DATA_INTERFACE,
	CDC_ACM_COMM_EPIN,
	CDC_ACM_DATA_EPIN,
	CDC_ACM_DATA_EPOUT,
	APP_USBD_CDC_COMM_PROTOCOL_AT_V250);
	

Error invalid conversion from 'void (*)(const app_usbd_class_inst_t*, app_usbd_cdc_acm_user_event_t)' {aka 'void (*)(const app_usbd_class_inst_s*, app_usbd_cdc_acm_user_event_e)'} to 'app_usbd_cdc_acm_user_ev_handler_t' {aka 'void (*)(const app_usbd_class_inst_s*, int)'} 

Changing the event type to int gives another error about initialization.

[nick_haman]

Actually, when I convert it to int:

static void cdc_acm_user_ev_handler(app_usbd_class_inst_t const * p_inst, int event);

Error designator order for field 'app_usbd_cdc_acm_inst_t::comm_interface' does not match declaration order in 'app_usbd_cdc_acm_inst_t' 

[SwRa]

Hi,

Which example are you trying to convert to C++.? Also, which compiler are you using.?

Regards,

Swathy

[Nguyen Hoan Hoang]

Data structure assignments must be in the order as the defined in the structure in C++.  You need to re-order the assignments.  For example.

typedef struct {
    int a;
    float b;
    char c;
} X_t;

// Wrong order, rejected by C++, accepted by C
X_t failedAssign = {
    .b = 1.0,
    .a = 3,
};

// Correct order, accepted by both
X_t goodAssign = {
    .a = 3;
    .b = 1.0,
};

Unfortunately there are a lot of those in the SDK.

[nick_haman]

SDK 16.0 using  usb_cdc_acm example.  GCC with -std=C++11.  

My workaround so far has been to place the above definition and callback function in a C module and to pass the arguments to the real callback in the C++ module.  

Also, when including app_usbd_cdc_acm.h in the C++ module it complained about a forward enum declaration.  I had to move the enum declaration into the app_usbd_cdc_acm_internal.h file and protect it with a #define:

#ifndef _APP_USBD_CDC_
#define _APP_USBD_CDC_


	typedef enum app_usbd_cdc_acm_user_event_e {
		APP_USBD_CDC_ACM_USER_EVT_RX_DONE, /**< User event RX_DONE.    */
		APP_USBD_CDC_ACM_USER_EVT_TX_DONE, /**< User event TX_DONE.    */

		APP_USBD_CDC_ACM_USER_EVT_PORT_OPEN, /**< User event PORT_OPEN.  */
		APP_USBD_CDC_ACM_USER_EVT_PORT_CLOSE, /**< User event PORT_CLOSE. */
	} app_usbd_cdc_acm_user_event_t;
	
#endif // !_APP_USBD_CDC_

/*lint -save -e165*/
/**
 * @brief Forward declaration of @ref app_usbd_cdc_acm_user_event_e.
 *
 */
enum app_usbd_cdc_acm_user_event_e;