https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60898
--- Comment #8 from Dominique d'Humieres <dominiq at lps dot ens.fr> --- Backtrace for the reduced test case * thread #1: tid = 0x1357c7a, 0x00000001000afb00 f951`count_st_nodes(st=<unavailable>) + 16 at symbol.c:3580, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x9) frame #0: 0x00000001000afb00 f951`count_st_nodes(st=<unavailable>) + 16 at symbol.c:3580 3577 if (!st) 3578 return 0; 3579 -> 3580 nodes = count_st_nodes (st->left); 3581 nodes++; 3582 nodes += count_st_nodes (st->right); 3583 (lldb) bt * thread #1: tid = 0x1357c7a, 0x00000001000afb00 f951`count_st_nodes(st=<unavailable>) + 16 at symbol.c:3580, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x9) * frame #0: 0x00000001000afb00 f951`count_st_nodes(st=<unavailable>) + 16 at symbol.c:3580 frame #1: 0x00000001000afb09 f951`count_st_nodes(st=<unavailable>) + 25 at symbol.c:3580 frame #2: 0x00000001000afb09 f951`count_st_nodes(st=<unavailable>) + 25 at symbol.c:3580 frame #3: 0x00000001000afb09 f951`count_st_nodes(st=<unavailable>) + 25 at symbol.c:3580 frame #4: 0x00000001000afb09 f951`count_st_nodes(st=<unavailable>) + 25 at symbol.c:3580 frame #5: 0x00000001000afb09 f951`count_st_nodes(st=<unavailable>) + 25 at symbol.c:3580 frame #6: 0x00000001000afb09 f951`count_st_nodes(st=<unavailable>) + 25 at symbol.c:3580 frame #7: 0x00000001000afb09 f951`count_st_nodes(st=<unavailable>) + 25 at symbol.c:3580 frame #8: 0x00000001000b1a61 f951`do_traverse_symtree(st=<unavailable>, st_func=0x0000000000000000, sym_func=0x00000001000f6040) + 49 at symbol.c:3617 frame #9: 0x00000001000f7255 f951`gfc_generate_function_code(ns=0x0000000142052e00) + 373 at trans-decl.c:5126 frame #10: 0x00000001000cb9b2 f951`gfc_generate_module_code(ns=<unavailable>) + 466 at trans.c:1998 frame #11: 0x00000001000817c3 f951`gfc_parse_file() + 167 at parse.c:4934 frame #12: 0x000000010008171c f951`gfc_parse_file() + 1116 frame #13: 0x00000001000c4c56 f951`gfc_be_parse_file + 38 at f95-lang.c:212 frame #14: 0x00000001008ba397 f951`compile_file + 39 at toplev.c:548 frame #15: 0x00000001008bcbbf f951`toplev_main(argc=2, argv=0x00007fff5fbff440) + 3327 at toplev.c:1946