bk commit into 5.0 tree (gshchepa:1.2623) BUG#36488

[<gshchepa]

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ChangeSet@stripped, 2008-05-13 20:27:46+05:00, gshchepa@stripped +3 -0
  Fixed bug #36488: regexp returns false matches, concatenating
                    with previous rows.
  
  The WHERE clause containing expression:
    CONCAT(empty_field1, empty_field2, ..., 'literal constant', ...)
      REGEXP 'regular expression'
  may return wrong matches.
  
  Optimization of the CONCAT function has been fixed.
  

  mysql-test/r/func_concat.result@stripped, 2008-05-13 20:27:07+05:00, gshchepa@stripped +7 -0
    Added test case for bug #36488.

  mysql-test/t/func_concat.test@stripped, 2008-05-13 20:27:08+05:00, gshchepa@stripped +10 -0
    Added test case for bug #36488.

  sql/item_strfunc.cc@stripped, 2008-05-13 20:27:09+05:00, gshchepa@stripped +6 -0
    Fixed bug #36488.
    The Item_func_concat::val_str method is optimized to
    use first non-empty argument of the CONCAT function for in-place
    result accumulation. This optimization is acceptable if that
    first argument is not a constant.
    However, current implementation checks this condition only for
    the first actual argument of the CONCAT function.
    So, the Item_func_concat::val_str method can corrupt values
    of, for example, literal strings by appending random data.
    
    The Item_func_concat::val_str method has been modified to take
    into account the ability to be modified in-place for the first
    non-empty argument.

diff -Nrup a/mysql-test/r/func_concat.result b/mysql-test/r/func_concat.result
--- a/mysql-test/r/func_concat.result	2006-06-15 02:46:27 +05:00
+++ b/mysql-test/r/func_concat.result	2008-05-13 20:27:07 +05:00
@@ -82,3 +82,10 @@ a
 1234562
 x
 drop table t1;
+CREATE TABLE t1 (c1 varchar(100), c2 varchar(100));
+INSERT INTO t1 VALUES ('',''), ('','First'), ('Random','Random');
+SELECT * FROM t1 WHERE CONCAT(c1,' ',c2) REGEXP 'First.*';
+c1	c2
+	First
+DROP TABLE t1;
+# End of 5.0 tests
diff -Nrup a/mysql-test/t/func_concat.test b/mysql-test/t/func_concat.test
--- a/mysql-test/t/func_concat.test	2006-06-15 00:54:05 +05:00
+++ b/mysql-test/t/func_concat.test	2008-05-13 20:27:08 +05:00
@@ -68,3 +68,13 @@ create table t1(f1 varchar(6)) charset=u
 insert into t1 values ("123456");
 select concat(f1, 2) a from t1 union select 'x' a from t1;
 drop table t1;
+
+#
+# Bug #36488: regexp returns false matches, concatenating with previous rows
+#
+CREATE TABLE t1 (c1 varchar(100), c2 varchar(100));
+INSERT INTO t1 VALUES ('',''), ('','First'), ('Random','Random');
+SELECT * FROM t1 WHERE CONCAT(c1,' ',c2) REGEXP 'First.*';
+DROP TABLE t1;
+
+--echo # End of 5.0 tests
diff -Nrup a/sql/item_strfunc.cc b/sql/item_strfunc.cc
--- a/sql/item_strfunc.cc	2007-10-11 16:07:09 +05:00
+++ b/sql/item_strfunc.cc	2008-05-13 20:27:09 +05:00
@@ -294,6 +294,12 @@ String *Item_func_concat::val_str(String
     {
       if (!(res=args[i]->val_str(str)))
 	goto null;
+      /*
+       CONCAT accumulates its result in the result of its the first
+       non-empty argument. Because of this we need is_const to be 
+       evaluated only for it.
+      */
+      is_const= args[i]->const_item() || !args[i]->used_tables();
     }
     else
     {