Use GC_EXTERNAL_LIST_LOOP_* where appropriate, fns.c src/ChangeLog addition: 2011-04-04 Aidan Kehoe <kehoea@parhasard.net> * lisp.h (GC_EXTERNAL_LIST_LOOP_3, GC_EXTERNAL_LIST_LOOP_4): New. * fns.c (count_with_tail, list_position_cons_before, FassocX): * fns.c (FrassocX, position, FdeleteX, FremoveX): * fns.c (list_delete_duplicates_from_end): * fns.c (Fdelete_duplicates, Fremove_duplicates, Freduce): * fns.c (Fnsubstitute, Fsubstitute, sublis, nsublis, Fnsublis): * fns.c (venn, nvenn, Funion, Fset_exclusive_or, Fnset_exclusive_or): Use GC_EXTERNAL_LIST_LOOP_* in the sequence functions in fns.c where appropriate, there were some corner cases where my old approach was unsafe (mainly if the circularity checking's tortoise lost GCPRO protection. Add GC_EXTERNAL_LIST_LOOP_{3,4}, analogous to GC_EXTERNAL_LIST_LOOP_2.