Bug#12711164 - 61676: RESULT OF DIV WITH DECIMAL AND INTEGER DOES NOT MAKE SENSE

Truncate result of decimal division before converting to integer.

mysql-test/r/func_math.result

@@ -709,3 +709,22 @@ foo
 select 999999999999999999999999999999999999999999999999999999999999999999999999999999999 % 0.0 as foo;
 foo
 NULL
+#
+# Bug#12711164 - 61676:
+# RESULT OF DIV WITH DECIMAL AND INTEGER DOES NOT MAKE SENSE 
+#
+select 5 div 2;
+5 div 2
+2
+select 5.0 div 2.0;
+5.0 div 2.0
+2
+select 5.0 div 2;
+5.0 div 2
+2
+select 5 div 2.0;
+5 div 2.0
+2
+select 5.9 div 2, 1.23456789e3 DIV 2, 1.23456789e9 DIV 2, 1.23456789e19 DIV 2;
+5.9 div 2	1.23456789e3 DIV 2	1.23456789e9 DIV 2	1.23456789e19 DIV 2
+2	617	617283945	6172839450000000000

mysql-test/t/func_math.test

@@ -547,3 +547,14 @@ let $nine_81=
 
 eval select $nine_81 % 0.1 as foo;
 eval select $nine_81 % 0.0 as foo;
+
+--echo #
+--echo # Bug#12711164 - 61676:
+--echo # RESULT OF DIV WITH DECIMAL AND INTEGER DOES NOT MAKE SENSE 
+--echo #
+
+select 5 div 2;
+select 5.0 div 2.0;
+select 5.0 div 2;
+select 5 div 2.0;
+select 5.9 div 2, 1.23456789e3 DIV 2, 1.23456789e9 DIV 2, 1.23456789e19 DIV 2;

sql/item_func.cc

@@ -1605,8 +1605,13 @@ longlong Item_func_int_div::val_int()
       return 0;
     }
 
+    my_decimal truncated;
+    const bool do_truncate= true;
+    if (my_decimal_round(E_DEC_FATAL_ERROR, &tmp, 0, do_truncate, &truncated))
+      DBUG_ASSERT(false);
+
     longlong res;
-    if (my_decimal2int(E_DEC_FATAL_ERROR, &tmp, unsigned_flag, &res) &
+    if (my_decimal2int(E_DEC_FATAL_ERROR, &truncated, unsigned_flag, &res) &
         E_DEC_OVERFLOW)
       raise_integer_overflow();
     return res;