http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56218
janus at gcc dot gnu.org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2013-02-06 CC| |janus at gcc dot gnu.org Summary|Segfault with allocatable |[OOP] Segfault with |intent(out) derived type |allocatable intent(out) |argument having allocatable |derived type argument |component |having allocatable | |component Ever Confirmed|0 |1 --- Comment #1 from janus at gcc dot gnu.org 2013-02-06 09:26:59 UTC --- Confirmed. I get a runtime segfault with 4.6, 4.7 and trunk (though with 4.6 it seems to be slightly different). Further reduced test case: program test_poly implicit none type :: foo_t real, allocatable :: a(:) end type class(foo_t), allocatable :: f call do_stuff(f) contains subroutine do_stuff (f) class(foo_t), intent(out), allocatable :: f end subroutine end program The dump shows the following: do_stuff (struct __class_test_poly_Foo_t_a & restrict f) { if (f->_data->a.data != 0B) { __builtin_free ((void *) f->_data->a.data); } f->_data->a.data = 0B; } So the problem is clear: Before freeing the allocatable components, we do not check whether 'f->_data' is null (i.e. whether 'f' is allocated at all).