Added --sql-mode=NO_UNSIGNED_SUBTRACTION

Docs/manual.texi:
  More information about UNSIGNED BIGINT arithmetic
sql/slave.cc:
  Make binary logs 4G safe
sql/slave.h:
  Make binary logs 4G safe
sql/sql_rename.cc:
  cleanup

1 files changed, 15 insertions, 0 deletions

diff --git a/sql/item_func.cc b/sql/item_func.cc
index 209fbea1674..5dcc638235f 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -280,6 +280,21 @@ longlong Item_func_plus::val_int()
   return (longlong) Item_func_plus::val();
 }
 
+
+/*
+  The following function is here to allow the user to force
+  subtraction of UNSIGNED BIGINT to return negative values.
+*/
+
+void Item_func_minus::fix_length_and_dec()
+{
+  Item_num_op::fix_length_and_dec();
+  if (unsigned_flag &&
+      (current_thd->sql_mode & MODE_NO_UNSIGNED_SUBTRACTION))
+    unsigned_flag=0;
+}
+
+
 double Item_func_minus::val()
 {
   double value=args[0]->val() - args[1]->val();