Bug #36244 MySQL CLI doesn't recognize standalone -- as comment

Description:
A comment that is just '--\n' is not recognized by MySQL CLI, and CLI commands like 'SYSTEM' are not detected in further statement, what causes syntax error:

mysql> #
mysql> -- a
mysql> --
    -> select 1;
+---+
| 1 |
+---+
| 1 | 
+---+
1 row in set (0.00 sec)

mysql> --
    -> system echo test
    -> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'system echo test' at line 2

How to repeat:
( echo --; echo system echo test) | mysql

Suggested fix:
if '--' is not treated as internal comment, at detect statements as SYSTEM in it.

The -- comment is not detected at all by mysql> it is a SQL comment and should thus be sent to the server for evaluation.

To be a valid SQL comment I think it has to have a two double dashes followed by a space. Please double check that.

Do note 'such as newline' at http://dev.mysql.com/doc/refman/5.0/en/ansi-diff-comments.html:

Standard SQL uses “--” as a start-comment sequence. MySQL Server uses “#” as the start comment character. MySQL Server 3.23.3 and up also supports a variant of the “--” comment style. That is, the “--” start-comment sequence must be followed by a space (or by a control character such as a newline).

Do note:
'-- ' is detected by CLI
'#\n' is detected by CLI
'--\n' is deceted by server, not by CLI

it is inconsistency both with standard and server behavior.

removed stale assignment

See below the patch for this bug:

=== modified file 'client/mysql.cc'
--- old/client/mysql.cc	2008-03-28 18:02:27 +0000
+++ new/client/mysql.cc	2008-06-23 12:26:19 +0000
@@ -2156,7 +2156,8 @@
     }
     else if (!*ml_comment && (!*in_string && (inchar == '#' ||
 			      inchar == '-' && pos[1] == '-' &&
-			      my_isspace(charset_info,pos[2]))))
+			      (my_isspace(charset_info,pos[2]) ||
+                               !pos[2]))))
     {
       // Flush previously accepted characters
       if (out != line)

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/48388

2641 Gleb Shchepa	2008-06-24
      Bug #36244: MySQL CLI doesn't recognize standalone -- or # 
                  as a commentary
      
      mysql client has been modified to interpret EOL after
      standalone -- and # commentary strings like whitespace 
      character (according to 
      http://dev.mysql.com/doc/refman/5.0/en/ansi-diff-comments.html)

revno 2641 is good with me.

That part of the code is rather ugly, so a comment would be helpful there.

/* The third byte is either whitespace or is the end of the line -- which would occur only because of the user sending newline -- which is itself whitespace and should also match. */

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/48394

2641 Gleb Shchepa	2008-06-24
      Bug #36244: MySQL CLI doesn't recognize standalone -- 
                  as a commentary
      
      mysql client has been modified to interpret EOL after
      standalone -- commentary strings like whitespace
      character (according to
      http://dev.mysql.com/doc/refman/5.0/en/ansi-diff-comments.html)

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/48407

2643 Gleb Shchepa	2008-06-24
      back-port from 5.1.
      
      Bug#35480: BOM detection code crashes mysql CLI with zero-sized input
            
      MySQL client crashed if no input was passed to it.

Pushed into 5.0.66

Noted in 5.0.66 changelog.

The mysql client failed to recognize comment lines consisting of --
followed by a newline.

Setting report to Patch queued pending push into 5.1.x/6.0.x.

Noted in 5.1.27, 6.0.6 changelogs.

Pushed into 5.0.68  (revid:kpettersson@mysql.com-20080715152926-s5kgnqhtu93b3c8v) (pib:2)
(Retry automatic marking, to ensure nothing is missed. cm01)

Fix is pushed to 5.1.28, not 5.1.27.

Pushed into 5.1.27  (revid:joerg@mysql.com-20080626161101-h5hsaluwtf05xdr2) (version source revid:joerg@mysql.com-20080626161101-h5hsaluwtf05xdr2) (pib:3)