lib: fix return value for n_m_reindex

Also update the documentation for the behaviour of n_m_get_thread_id
that this fix relies on.

2 files changed, 6 insertions, 4 deletions

diff --git a/lib/message.cc b/lib/message.cc
index 09708ed9..87448101 100644
--- a/lib/message.cc
+++ b/lib/message.cc
@@ -2205,8 +2205,10 @@ notmuch_message_reindex (notmuch_message_t *message,
     /* Save in case we need to delete message */
     orig_thread_id = notmuch_message_get_thread_id (message);
     if (! orig_thread_id) {
-	/* XXX TODO: make up new error return? */
-	INTERNAL_ERROR ("message without thread-id");
+	/* the following is correct as long as there is only one reason
+	   n_m_get_thread_id returns NULL
+	*/
+	return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
     }
 
     /* strdup it because the metadata may be invalidated */
diff --git a/lib/notmuch.h b/lib/notmuch.h
index 82d6c10f..0dd442d4 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -1378,8 +1378,8 @@ notmuch_message_get_message_id (notmuch_message_t *message);
  * notmuch_message_destroy on 'message' or until a query from which it
  * derived is destroyed).
  *
- * This function will not return NULL since Notmuch ensures that every
- * message belongs to a single thread.
+ * This function will return NULL if triggers an unhandled Xapian
+ * exception.
  */
 const char *
 notmuch_message_get_thread_id (notmuch_message_t *message);