https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96041
--- Comment #6 from anlauf at gcc dot gnu.org --- On x86_64 I never reach symbol.c:2662, since the code returns from line 2659. This the closest I get to your backtrace: Breakpoint 2, free_st_labels (label=0x0) at ../../gcc-trunk/gcc/fortran/symbol.c:2659 2659 if (label == NULL) (gdb) bt #0 free_st_labels (label=0x0) at ../../gcc-trunk/gcc/fortran/symbol.c:2659 #1 0x000000000073ad9a in gfc_free_namespace (ns=0x27c7c60) at ../../gcc-trunk/gcc/fortran/symbol.c:4050 #2 0x000000000073af45 in gfc_free_symbol (sym=0x27c7b00) at ../../gcc-trunk/gcc/fortran/symbol.c:3091 #3 0x000000000073b09f in free_sym_tree (sym_tree=0x275f280) at ../../gcc-trunk/gcc/fortran/symbol.c:3902 #4 0x000000000073b096 in free_sym_tree (sym_tree=0x27c5a00) at ../../gcc-trunk/gcc/fortran/symbol.c:3900 #5 0x000000000073b08d in free_sym_tree (sym_tree=0x275fb90) at ../../gcc-trunk/gcc/fortran/symbol.c:3899 #6 0x000000000073b08d in free_sym_tree (sym_tree=0x27c79a0) at ../../gcc-trunk/gcc/fortran/symbol.c:3899 #7 0x000000000073ad12 in gfc_free_namespace (ns=0x27c2670) at ../../gcc-trunk/gcc/fortran/symbol.c:4041 #8 0x000000000073b34b in gfc_symbol_done_2 () at ../../gcc-trunk/gcc/fortran/symbol.c:4101 #9 0x00000000006d9379 in gfc_done_2 () at ../../gcc-trunk/gcc/fortran/misc.c:358 #10 0x00000000006f2053 in clean_up_modules (gsym=0x275e880) at ../../gcc-trunk/gcc/fortran/parse.c:6267 #11 0x00000000006f201d in clean_up_modules (gsym=0x2823580) at ../../gcc-trunk/gcc/fortran/parse.c:6259 #12 0x00000000006fd73c in translate_all_program_units (gfc_global_ns_list=<optimized out>) at ../../gcc-trunk/gcc/fortran/parse.c:6330 #13 gfc_parse_file () at ../../gcc-trunk/gcc/fortran/parse.c:6546 #14 0x0000000000749f00 in gfc_be_parse_file () at ../../gcc-trunk/gcc/fortran/f95-lang.c:212 #15 0x0000000000d74e8f in compile_file () at ../../gcc-trunk/gcc/toplev.c:458 #16 0x00000000006621c9 in do_compile () at ../../gcc-trunk/gcc/toplev.c:2307 #17 toplev::main (this=this@entry=0x7fffffffd4ae, argc=<optimized out>, argc@entry=2, argv=<optimized out>, argv@entry=0x7fffffffd5a8) at ../../gcc-trunk/gcc/toplev.c:2446 #18 0x000000000066602b in main (argc=2, argv=0x7fffffffd5a8) at ../../gcc-trunk/gcc/main.c:39 (gdb) p label $1 = (gfc_st_label *) 0x0