The following script :

<?
class toto {
  function titi() { }
}
$toto = new toto;
echo function_exists($toto->titi);
?>

generates a segmentation fault with the following backtrace :

Program received signal SIGSEGV, Segmentation fault.
0x8060a38 in _estrdup (s=0x0) at alloc.c:267
267             length = strlen(s)+1;
(gdb) bt
#0  0x8060a38 in _estrdup (s=0x0) at alloc.c:267
#1  0x8067b6c in php3_function_exists (ht=0x80da418, return_value=0x80b133c, 
    list=0x80c2380, plist=0x80c2340) at functions/basic_functions.c:2063
#2  0x80506b3 in phpparse () at control_structures_inline.h:934
#3  0x8059cc8 in php3_parse (yyin=0x80d3f20) at main.c:1553
#4  0x805a302 in main (argc=2, argv=0xbffff9a4) at main.c:1862

OK, I know it shouldn't do what I expect anyway, but it crashes...

NB : the bug doesn't occur under PHP4b3.