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
