[RFC - doc] Add note about the possibility of symbols getting moved across blocks

[Tom Tromey]

>>>>> "Eli" == Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Wed, 25 Apr 2012 13:36:20 +0530
>> From: Siva Chandra <sivachandra@google.com>
>> 
>> A @code{gdb.Block} is iterable.  The iterator returns the symbols
>> -(@pxref{Symbols In Python}) local to the block.
>> +(@pxref{Symbols In Python}) local to the block.  Users using this
>> +feature should keep in mind that future improvements to the internal
>> +representation, of symbols and symbol tables, can move symbols across
>> +blocks within a symbol table.

Eli> Thanks.  But I still don't see how the warning is useful.  What should
Eli> I do or not do if I want to avoid whatever dangers you warn me about?

You could test new versions of gdb to be sure they conform to your
expectations.

Tom