px4_main_t: fix method declaration throughout the code base

px4_main_t is defined as:
typedef int (*px4_main_t)(int argc, char *argv[]);
which matches with the definition in NuttX, given to task_create

src/drivers/distance_sensor/ulanding/ulanding.cpp

@@ -122,7 +122,7 @@ private:
 	unsigned 	_tail;
 	uint8_t 	_buf[BUF_LEN];
 
-	static void task_main_trampoline(int argc, char *argv[]);
+	static int task_main_trampoline(int argc, char *argv[]);
 	void task_main();
 
 	bool read_and_parse(uint8_t *buf, int len, float *range);
@@ -299,10 +299,11 @@ Radar::init()
 	return ret;
 }
 
-void
+int
 Radar::task_main_trampoline(int argc, char *argv[])
 {
 	radar::g_dev->task_main();
+	return 0;
 }
 
 int

src/drivers/gps/gps.cpp

@@ -134,7 +134,7 @@ public:
 	/**
 	 * task spawn trampoline for the secondary GPS
 	 */
-	static void run_trampoline_secondary(int argc, char *argv[]);
+	static int run_trampoline_secondary(int argc, char *argv[]);
 
 	/** @see ModuleBase::run() */
 	void run() override;
@@ -997,7 +997,7 @@ int GPS::task_spawn(int argc, char *argv[], Instance instance)
 	return 0;
 }
 
-void GPS::run_trampoline_secondary(int argc, char *argv[])
+int GPS::run_trampoline_secondary(int argc, char *argv[])
 {
 
 #ifdef __PX4_NUTTX
@@ -1014,6 +1014,7 @@ void GPS::run_trampoline_secondary(int argc, char *argv[])
 		_secondary_instance = nullptr;
 		delete gps;
 	}
+	return 0;
 }
 GPS *GPS::instantiate(int argc, char *argv[])
 {

src/examples/bottle_drop/bottle_drop.cpp

@@ -158,7 +158,7 @@ private:
 	/**
 	 * Shim for calling task_main from task_create.
 	 */
-	static void	task_main_trampoline(int argc, char *argv[]);
+	static int	task_main_trampoline(int argc, char *argv[]);
 };
 
 namespace bottle_drop
@@ -868,10 +868,11 @@ BottleDrop::answer_command(struct vehicle_command_s *cmd, unsigned result)
 	}
 }
 
-void
+int
 BottleDrop::task_main_trampoline(int argc, char *argv[])
 {
 	bottle_drop::g_bottle_drop->task_main();
+	return 0;
 }
 
 static void usage()

src/modules/attitude_estimator_q/attitude_estimator_q_main.cpp

@@ -91,7 +91,7 @@ public:
 	 */
 	int		start();
 
-	static void	task_main_trampoline(int argc, char *argv[]);
+	static int	task_main_trampoline(int argc, char *argv[]);
 
 	void		task_main();
 
@@ -243,9 +243,10 @@ int AttitudeEstimatorQ::start()
 	return OK;
 }
 
-void AttitudeEstimatorQ::task_main_trampoline(int argc, char *argv[])
+int AttitudeEstimatorQ::task_main_trampoline(int argc, char *argv[])
 {
 	attitude_estimator_q::instance->task_main();
+	return 0;
 }
 
 void AttitudeEstimatorQ::task_main()

src/modules/events/temperature_calibration/task.cpp

@@ -83,7 +83,7 @@ public:
 	 */
 	int		start();
 
-	static void do_temperature_calibration(int argc, char *argv[]);
+	static int do_temperature_calibration(int argc, char *argv[]);
 
 	void		task_main();
 
@@ -320,9 +320,10 @@ void TemperatureCalibration::task_main()
 	PX4_INFO("Exiting temperature calibration task");
 }
 
-void TemperatureCalibration::do_temperature_calibration(int argc, char *argv[])
+int TemperatureCalibration::do_temperature_calibration(int argc, char *argv[])
 {
 	temperature_calibration::instance->task_main();
+	return 0;
 }
 
 int TemperatureCalibration::start()

src/modules/gnd_att_control/GroundRoverAttitudeControl.cpp

@@ -174,10 +174,11 @@ GroundRoverAttitudeControl::battery_status_poll()
 	}
 }
 
-void
+int
 GroundRoverAttitudeControl::task_main_trampoline(int argc, char *argv[])
 {
 	att_gnd_control::g_control->task_main();
+	return 0;
 }
 
 void

src/modules/gnd_att_control/GroundRoverAttitudeControl.hpp

@@ -136,7 +136,7 @@ private:
 	void		vehicle_attitude_setpoint_poll();
 	void		battery_status_poll();
 
-	static void	task_main_trampoline(int argc, char *argv[]);
+	static int	task_main_trampoline(int argc, char *argv[]);
 	void		task_main();
 
 };

src/modules/gnd_pos_control/GroundRoverPositionControl.cpp

@@ -479,27 +479,27 @@ GroundRoverPositionControl::task_main()
 	_control_task = -1;
 }
 
-void
+int
 GroundRoverPositionControl::task_main_trampoline(int argc, char *argv[])
 {
 	gnd_control::g_control = new GroundRoverPositionControl();
 
 	if (gnd_control::g_control == nullptr) {
 		warnx("OUT OF MEM");
-		return;
+		return -1;
 	}
 
 	/* only returns on exit */
 	gnd_control::g_control->task_main();
 	delete gnd_control::g_control;
 	gnd_control::g_control = nullptr;
+	return 0;
 }
 
 int
 GroundRoverPositionControl::start()
 {
 	ASSERT(_control_task == -1);
-	warn("Starting by marco");
 
 	/* start the task */
 	_control_task = px4_task_spawn_cmd("gnd_pos_ctrl",
@@ -508,7 +508,6 @@ GroundRoverPositionControl::start()
 					   1700,
 					   (px4_main_t)&GroundRoverPositionControl::task_main_trampoline,
 					   nullptr);
-	warn("done");
 
 	if (_control_task < 0) {
 		warn("task start failed");

src/modules/gnd_pos_control/GroundRoverPositionControl.hpp

@@ -202,7 +202,7 @@ private:
 	/**
 	 * Shim for calling task_main from task_create.
 	 */
-	static void	task_main_trampoline(int argc, char *argv[]);
+	static int	task_main_trampoline(int argc, char *argv[]);
 
 	/**
 	 * Main sensor collection task.

src/modules/mc_pos_control/mc_pos_control_main.cpp

@@ -412,7 +412,7 @@ private:
 	/**
 	 * Shim for calling task_main from task_create.
 	 */
-	static void	task_main_trampoline(int argc, char *argv[]);
+	static int	task_main_trampoline(int argc, char *argv[]);
 
 	/**
 	 * Main sensor collection task.
@@ -768,10 +768,11 @@ MulticopterPositionControl::throttle_curve(float ctl, float ctr)
 	}
 }
 
-void
+int
 MulticopterPositionControl::task_main_trampoline(int argc, char *argv[])
 {
 	pos_control::g_control->task_main();
+	return 0;
 }
 
 void

src/modules/simulator/gpssim/gpssim.cpp

@@ -136,7 +136,7 @@ private:
 	/**
 	 * Trampoline to the worker task
 	 */
-	static void			task_main_trampoline(void *arg);
+	static int			task_main_trampoline(int argc, char *argv[]);
 
 
 	/**
@@ -273,10 +273,11 @@ GPSSIM::devIOCTL(unsigned long cmd, unsigned long arg)
 	return ret;
 }
 
-void
+int
-GPSSIM::task_main_trampoline(void *arg)
+GPSSIM::task_main_trampoline(int argc, char *argv[])
 {
 	g_dev->task_main();
+	return 0;
 }
 
 int

src/modules/uORB/uORB_tests/uORBTest_UnitTest.cpp

@@ -401,7 +401,7 @@ int uORBTest::UnitTest::test_multi()
 
 
 
-int uORBTest::UnitTest::pub_test_multi2_entry(char *const argv[])
+int uORBTest::UnitTest::pub_test_multi2_entry(int argc, char *argv[])
 {
 	uORBTest::UnitTest &t = uORBTest::UnitTest::instance();
 	return t.pub_test_multi2_main();
@@ -707,7 +707,7 @@ int uORBTest::UnitTest::test_queue()
 }
 
 
-int uORBTest::UnitTest::pub_test_queue_entry(char *const argv[])
+int uORBTest::UnitTest::pub_test_queue_entry(int argc, char *argv[])
 {
 	uORBTest::UnitTest &t = uORBTest::UnitTest::instance();
 	return t.pub_test_queue_main();
@@ -842,7 +842,7 @@ int uORBTest::UnitTest::test_note(const char *fmt, ...)
 	return OK;
 }
 
-int uORBTest::UnitTest::pubsubtest_threadEntry(char *const argv[])
+int uORBTest::UnitTest::pubsubtest_threadEntry(int argc, char *argv[])
 {
 	uORBTest::UnitTest &t = uORBTest::UnitTest::instance();
 	return t.pubsublatency_main();

src/modules/uORB/uORB_tests/uORBTest_UnitTest.hpp

@@ -86,10 +86,10 @@ private:
 	// Disallow copy
 	UnitTest(const uORBTest::UnitTest & /*unused*/) = delete;
 
-	static int pubsubtest_threadEntry(char *const argv[]);
+	static int pubsubtest_threadEntry(int argc, char *argv[]);
 	int pubsublatency_main();
 
-	static int pub_test_multi2_entry(char *const argv[]);
+	static int pub_test_multi2_entry(int argc, char *argv[]);
 	int pub_test_multi2_main();
 
 	volatile bool _thread_should_exit;
@@ -111,7 +111,7 @@ private:
 
 	/* queuing tests */
 	int test_queue();
-	static int pub_test_queue_entry(char *const argv[]);
+	static int pub_test_queue_entry(int argc, char *argv[]);
 	int pub_test_queue_main();
 	int test_queue_poll_notify();
 	volatile int _num_messages_sent = 0;

src/modules/vtol_att_control/vtol_att_control_main.cpp

@@ -572,10 +572,11 @@ void VtolAttitudeControl::fill_fw_att_rates_sp()
 	}
 }
 
-void
+int
 VtolAttitudeControl::task_main_trampoline(int argc, char *argv[])
 {
 	VTOL_att_control::g_control->task_main();
+	return 0;
 }
 
 void VtolAttitudeControl::task_main()

src/modules/vtol_att_control/vtol_att_control_main.h

@@ -214,7 +214,7 @@ private:
 //*****************Member functions***********************************************************************
 
 	void 		task_main();	//main task
-	static void	task_main_trampoline(int argc, char *argv[]);	//Shim for calling task_main from task_create.
+	static int	task_main_trampoline(int argc, char *argv[]);	//Shim for calling task_main from task_create.
 
 	void		land_detected_poll();
 	void		tecs_status_poll();

src/platforms/px4_module.h

@@ -149,8 +149,9 @@ public:
 	 * @param argc start argument(s)
 	 * @param argv start argument(s)
 	 */
-	static void run_trampoline(int argc, char *argv[])
+	static int run_trampoline(int argc, char *argv[])
 	{
+		int ret = 0;
 
 #ifdef __PX4_NUTTX
 		// on NuttX task_create() adds the task name as first argument
@@ -166,9 +167,12 @@ public:
 
 		} else {
 			PX4_ERR("failed to instantiate object");
+			ret = -1;
 		}
 
 		exit_and_cleanup();
+
+		return ret;
 	}
 
 	/**