convenience variable rejected in array cast

[Vincent Liard]

Hello,

I am experiencing trouble with GDB 6.8-debian through emacs 22.2.1 while 
casting a pointer to an array using "convenience variables" to indicate 
its dimensions.

As an example, I have defined variables $lines and $columns.
(gdb) set $lines = 6
(gdb) set $columns = 6

I have an 6x6 array of doubles called "p" as shown below.
(gdb) print (double[6][6])*p
$12 = {{1, 0, 0, 0, 0, 0}, {0, 1, 0, 0, 0, 0}, {0, 0, 1, 0, 0, 0}, {0, 0, 
0, 1, 0, 0}, {0, 0, 0, 0, 1, 0}, {0, 0, 0, 0, 0, 1}}

I just replace the explicit constants (6) by my variables $lines and 
$columns in the above expression and it nolonger works.
(gdb) print (double[$lines][$columns])*p
A syntax error in expression, near `$lines][$columns])*p'.

It may be a limitation, not a bug, but I have found no clue. Could anyone 
tell me if I'm doing anything wrong ?
Thanks !

Vincent Liard