dave mitchell uaufmiabyncom wed nov 07 2007 071801pm 0000 nicholas clark wrote wed nov 07 2007 082332am 0800 jerry hedden wrote given following code attached usrbinperl use strict use warnings warnings redefine isa universalisa universalisa sub printjumping original isan comment goto isa main obj bless someclass printuniversalisaobj undef ok ok n 5100 produces jumping original isa segmentation fault core dumped 19376 jumping original isa 19376 invalid read size 4 19376 0x8171f56 s_varname svc11808 hmm happening use uninit warning occurs within xs code universalisa turns xs code called via goto call stack pad parent ie main sub f goto somexssub f xs code sees pad cv pl_main_cv rather f somexssub causes guessing code go around poking wrong pads badness coredumps follow think deal suspect theres also similar issue normal pp_entersub calls xs code late ponder worry another day segv dont know unitialised warning isnt second arg isa undef hofstadters law always takes longer expect even take account hofstadters law thu 07 aug 2008 182127 0000 perl 47233 core dump caused goto