I never understood why I need to write void as empty function arguments.

src/class/usbtmc/usbtmc_device.c

@@ -511,7 +511,7 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
     switch(usbtmc_state.state) {
     case STATE_TX_SHORTED:
       TU_VERIFY(atomicChangeState(STATE_TX_SHORTED, STATE_NAK));
-      TU_VERIFY(tud_usbtmc_app_msgBulkIn_complete_cb(rhport));
+      TU_VERIFY(tud_usbtmc_app_msgBulkIn_complete_cb());
       break;
 
     case STATE_TX_INITIATED:
@@ -578,11 +578,11 @@ bool usbtmcd_control_request_cb(uint8_t rhport, tusb_control_request_t const * r
       criticalEnter();
       usbtmc_state.state = STATE_NAK; // USBD core has placed EP in NAK state for us
       criticalLeave();
-      usmtmcd_app_bulkOut_clearFeature_cb(rhport);
+      usmtmcd_app_bulkOut_clearFeature_cb();
     }
     else if (ep_addr == usbtmc_state.ep_bulk_in)
     {
-      usmtmcd_app_bulkIn_clearFeature_cb(rhport);
+      usmtmcd_app_bulkIn_clearFeature_cb();
     }
     else
     {

src/class/usbtmc/usbtmc_device.h

@@ -69,11 +69,11 @@ void tud_usbtmc_app_open_cb(uint8_t interface_id);
 bool tud_usbtmc_app_msgBulkOut_start_cb(usbtmc_msg_request_dev_dep_out const * msgHeader);
 // transfer_complete does not imply that a message is complete.
 bool tud_usbtmc_app_msg_data_cb( void *data, size_t len, bool transfer_complete);
-void usmtmcd_app_bulkOut_clearFeature_cb(); // Notice to clear and abort the pending BULK out transfer
+void usmtmcd_app_bulkOut_clearFeature_cb(void); // Notice to clear and abort the pending BULK out transfer
 
 bool tud_usbtmc_app_msgBulkIn_request_cb(usbtmc_msg_request_dev_dep_in const * request);
-bool tud_usbtmc_app_msgBulkIn_complete_cb();
-void usmtmcd_app_bulkIn_clearFeature_cb(); // Notice to clear and abort the pending BULK out transfer
+bool tud_usbtmc_app_msgBulkIn_complete_cb(void);
+void usmtmcd_app_bulkIn_clearFeature_cb(void); // Notice to clear and abort the pending BULK out transfer
 
 bool tud_usbtmc_app_initiate_abort_bulk_in_cb(uint8_t *tmcResult);
 bool tud_usbtmc_app_initiate_abort_bulk_out_cb(uint8_t *tmcResult);
@@ -103,7 +103,7 @@ bool usbtmcd_transmit_dev_msg_data(
     const void * data, size_t len,
     bool endOfMessage, bool usingTermChar);
 
-bool usbtmcd_start_bus_read();
+bool usbtmcd_start_bus_read(void);
 
 
 /* "callbacks" from USB device core */