Fix for BUG#6825: When calculating Item_func_neg::max_length, add 1 for '-'.

For numeric constants we only need to add, since the parser doesn't produce 
negative numbers. 
For strings we only add (we actually could substract 1 if given string is a constant 
and it has '-number' form but we're not doing that because 
 * we set max_length bigger then necessary in other cases as well.  
 * the current solution is simpler and safer (bigger max_length is better then cutting out)


mysql-test/r/func_concat.result:
  Test for BUG#6825
mysql-test/r/metadata.result:
  Ajusted results according to fix of bug BUG#6825:length(-1) = 2 , not 1
mysql-test/t/func_concat.test:
  Test for BUG#6825

1 files changed, 16 insertions, 0 deletions

diff --git a/mysql-test/t/func_concat.test b/mysql-test/t/func_concat.test
index 0cf1502b10e..78818cdda4e 100644
--- a/mysql-test/t/func_concat.test
+++ b/mysql-test/t/func_concat.test
@@ -34,3 +34,19 @@ create table t1 (a char(4), b double, c date, d tinyint(4));
 insert into t1 values ('AAAA', 105, '2003-03-01', 1);
 select * from t1 where concat(A,C,B,D) = 'AAAA2003-03-011051';
 drop table t1;
+
+# BUG#6825 
+select 'a' union select concat('a', -4);
+select 'a' union select concat('a', -4.5);
+
+select 'a' union select concat('a', -(4 + 1));
+select 'a' union select concat('a', 4 - 5);
+
+select 'a' union select concat('a', -'3');
+select 'a' union select concat('a', -concat('3',4));
+
+select 'a' union select concat('a', -0);
+select 'a' union select concat('a', -0.0);
+
+select 'a' union select concat('a', -0.0000);
+