Introduce jerry_port_track_promise_rejection (#4451)

This patch resolves #2931.

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

docs/05.PORT-API.md

@@ -151,6 +151,32 @@ jerry_port_get_native_module (jerry_value_t name) /**< module specifier */
 }
 ```
 
+## Promise
+
+```c
+/**
+ * HostPromiseRejectionTracker operations
+ */
+typedef enum
+{
+  JERRY_PROMISE_REJECTION_OPERATION_REJECT, /**< promise is rejected without any handlers */
+  JERRY_PROMISE_REJECTION_OPERATION_HANDLE, /**< handler is added to a rejected promise for the first time */
+} jerry_promise_rejection_operation_t;
+
+/**
+ * Track unhandled promise rejections.
+ *
+ * Note:
+ *      This port function is called by jerry-core when JERRY_BUILTIN_PROMISE
+ *      is enabled.
+ *
+ * @param promise rejected promise
+ * @param operation HostPromiseRejectionTracker operation
+ */
+void jerry_port_track_promise_rejection (const jerry_value_t promise,
+                                         const jerry_promise_rejection_operation_t operation);
+```
+
 ## Date
 
 ```c
@@ -392,3 +418,32 @@ void jerry_port_sleep (uint32_t sleep_time)
 } /* jerry_port_sleep */
 #endif /* defined (JERRY_DEBUGGER) && (JERRY_DEBUGGER == 1) */
 ```
+
+## Promise
+
+```c
+#include "jerryscript-port.h"
+
+/**
+ * Default implementation of jerry_port_track_promise_rejection.
+ * Prints the reason of the unhandled rejections.
+ */
+void
+jerry_port_track_promise_rejection (const jerry_value_t promise, /**< rejected promise */
+                                    const jerry_promise_rejection_operation_t operation) /**< operation */
+{
+  (void) operation; /* unused */
+
+  jerry_value_t reason = jerry_get_promise_result (promise);
+  jerry_value_t reason_to_string = jerry_value_to_string (reason);
+  jerry_size_t req_sz = jerry_get_utf8_string_size (reason_to_string);
+  jerry_char_t str_buf_p[req_sz + 1];
+  jerry_string_to_utf8_char_buffer (reason_to_string, str_buf_p, req_sz);
+  str_buf_p[req_sz] = '\0';
+
+  jerry_release_value (reason_to_string);
+  jerry_release_value (reason);
+
+  printf ("Uncaught (in promise) %s\n", str_buf_p);
+} /* jerry_port_track_promise_rejection */
+```