xdebug-2.2.5 tested with php 5.5.9 and 5.5.16 segfaults here:

Program terminated with signal 11, Segmentation fault.
#0 0x00007fccf0d22dca in xdebug_build_fname (edata=0x7fff7c6eac80, tmp=0x3452930)
at /usr/src/xdebug-2.2.5/xdebug_stack.c:918
918 tmp->function = xdebug_sprintf(
(gdb) list
913 }
914
915 if (!fname) {
916 fname = "whoops";
917 }
918 tmp->function = xdebug_sprintf(
919 "%s:{%s:%d}",
920 edata->function_state.function->common.function_name,
921 fname,
922 edata->opline->lineno

(gdb) p edata
$10 = (zend_execute_data ) 0x7fff7c6eac80
(gdb) p edata->opline
$11 = (struct _zend_op ) 0x0
(gdb) p *edata
$12 = {opline = 0x0, function_state = {function = 0x27f7bd0, arguments = 0x7fccf12fb6c0}, op_array = 0x0,
object = 0x0, symbol_table = 0x0, prev_execute_data = 0x7fccf12fb5e0, old_error_reporting = 0x0,
nested = 0 '\000', original_return_value = 0x2bae650, current_scope = 0x29477c0,
current_called_scope = 0x7fccf12f9d68, current_this = 0x0, fast_ret = 0x7fccf12f9da8,
call_slots = 0x7fccf12fb670, call = 0x7fccf12fb670}