a small bug fix

Docs/manual.texi

@@ -50364,6 +50364,10 @@ each individual 4.0.x release.
 
 @itemize @bullet
 @item
+Fixed a bug in guessing a field type out of the function. The error was 
+introduced in 4.0.3 so that field type depended on the first argument to
+the function instead of the function itself
+@item
 Fixed a bug with wildcarded fields in select list, which led to the wrong 
 number of elements in a list containing all fields
 @item

mysql-test/r/create.result

@@ -136,3 +136,8 @@ t1	CREATE TABLE `t1` (
 drop table t1;
 create table t1 select if(1,'1','0'), month("2002-08-02");
 drop table t1;
+create table t1 select if('2002'='2002','Y','N');
+select * from t1;
+if('2002'='2002','Y','N')
+Y
+drop table if exists t1;

mysql-test/t/create.test

@@ -91,3 +91,6 @@ show create table t1;
 drop table t1;
 create table t1 select if(1,'1','0'), month("2002-08-02");
 drop table t1;
+create table t1 select if('2002'='2002','Y','N');
+select * from t1;
+drop table if exists t1;

sql/item_func.cc

@@ -173,7 +173,7 @@ Field *Item_func::tmp_table_field(TABLE *t_arg)
 
   if (!t_arg)
     return result_field;
-  switch (args[0]->result_type()) {
+  switch (result_type()) {
   case INT_RESULT:
     if (max_length > 11)
       res= new Field_longlong(max_length, maybe_null, name, t_arg,