BUG#11927: Warnings shown for CAST( chr as signed) but not (chr + 0)

 When implicitly converting string fields to numbers the 
 string-to-number conversion error was not sent to the client.
 Added code to send the conversion error as warning.
 
 We also need to prevent generation of warnings from the places
 where val_xxx() methods are called for the sole purpose of updating
 the Item::null_value flag.
 To achieve that a special function is added (and called) : 
 update_null_value(). This function will set the no_errors flag and
 will call val_xxx(). The warning generation in Field_string::val_xxx()
 will use the flag when generating the conversion warnings. 

1 files changed, 4 insertions, 0 deletions

diff --git a/mysql-test/r/compare.result b/mysql-test/r/compare.result
index da0ca8ddba1..c141b255716 100644
--- a/mysql-test/r/compare.result
+++ b/mysql-test/r/compare.result
@@ -46,6 +46,10 @@ create table t1 (a tinyint(1),b binary(1));
 insert into t1 values (0x01,0x01);
 select * from t1 where a=b;
 a	b
+Warnings:
+Warning	1292	Truncated incorrect DOUBLE value: '
'
 select * from t1 where a=b and b=0x01;
 a	b
+Warnings:
+Warning	1292	Truncated incorrect DOUBLE value: '
'
 drop table if exists t1;