Description:
------------
When using SoapClient and a nested object structure to send I get a SegFault due to a stack overflow

I have used gdb to look at the backtrace and it looks like this:

[..snip..]
#34426 0x081a974d in ?? ()
#34427 0x081ad9f1 in sdl_guess_convert_xml ()
#34428 0x081a974d in ?? ()
#34429 0x081ad9f1 in sdl_guess_convert_xml ()
#34430 0x081a974d in ?? ()
#34431 0x081ad9f1 in sdl_guess_convert_xml ()
#34432 0x081a974d in ?? ()
#34433 0x081ad9f1 in sdl_guess_convert_xml ()
#34434 0x081a974d in ?? ()
#34435 0x081ad9f1 in sdl_guess_convert_xml ()
#34436 0x081a974d in ?? ()
#34437 0x081ad9f1 in sdl_guess_convert_xml ()
#34438 0x081a974d in ?? ()
#34439 0x081ad9f1 in sdl_guess_convert_xml ()
#34440 0x081a974d in ?? ()
#34441 0x081ad9f1 in sdl_guess_convert_xml ()
#34442 0x081a974d in ?? ()
[.. snip ..]

Reproduce code:
---------------
I have a whole bunch of auto generated classes made from a WSDL document. Maybe the bug is due to the fact that i have classes called "string" that I inherit from (string is a type in WSDL as far as I could see).

Expected result:
----------------
That we actually send the request and receive a reply.

Actual result:
--------------
Segmentation Fault (stack overflow it seems in gdb)