The exact warning message is: Access to field 'mse_start' results in a
dereference of a null pointer (loaded from variable 'new_mark_stack_ptr').
* typd_mlc.c (GC_array_mark_proc): Add assertion that mark_stack_ptr is
non-NULL (thus orig_mark_stack_ptr is non-NULL too).
/* and request a mark stack expansion. */
/* This cannot cause a mark stack overflow, since it replaces */
/* the original array entry. */
+ GC_ASSERT(mark_stack_ptr != NULL);
GC_mark_stack_too_small = TRUE;
new_mark_stack_ptr = orig_mark_stack_ptr + 1;
new_mark_stack_ptr -> mse_start = (ptr_t)addr;