commit bash-20161216 snapshot

lib/readline/doc/hsuser.texi

@@ -198,8 +198,12 @@ with the other options to replace the history list completely.
 
 @item -d @var{offset}
 Delete the history entry at position @var{offset}.
-@var{offset} should be specified as it appears when the history is
-displayed.
+If @var{offset} is positive, it should be specified as it appears when
+the history is displayed.
+If @var{offset} is negative, it is interpreted as relative to one greater
+than the last history position, so negative indices count back from the
+end of the history, and an index of @samp{-1} refers to the current
+@code{history -d} command.
 
 @item -a
 Append the new history lines to the history file.

lib/readline/history.c

@@ -498,14 +498,27 @@ remove_history (which)
 {
   HIST_ENTRY *return_value;
   register int i;
+#if 1
+  int nentries;
+  HIST_ENTRY **start, **end;
+#endif
 
   if (which < 0 || which >= history_length || history_length ==  0 || the_history == 0)
     return ((HIST_ENTRY *)NULL);
 
   return_value = the_history[which];
 
+#if 1
+  /* Copy the rest of the entries, moving down one slot.  Copy includes
+     trailing NULL.  */
+  nentries = history_length - which;
+  start = the_history + which;
+  end = start + 1;
+  memmove (start, end, nentries * sizeof (HIST_ENTRY *));
+#else
   for (i = which; i < history_length; i++)
     the_history[i] = the_history[i + 1];
+#endif
 
   history_length--;