AddressSanitizer:DEADLYSIGNAL
=================================================================
==8767==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000008 (pc 0x7f01aa487f31 bp 0x000000000008 sp 0x7ffdb49a55b8 T0)
==8767==The signal is caused by a READ memory access.
==8767==Hint: address points to the zero page.
    #0 0x7f01aa487f30  (/lib/x86_64-linux-gnu/libc.so.6+0x15bf30)
    #1 0x7f01aa39c5d4 in fputs (/lib/x86_64-linux-gnu/libc.so.6+0x705d4)
    #2 0x55809e860bf4 in print(BigStr*) mycpp/gc_builtins.cc:14
    #3 0x55809e85cc5f in gc_stack_roots::print_list(List<BigStr*>*) (/home/uke/oil/_bin/cxx-asan+gcalways/mycpp/examples/gc_stack_roots.mycpp+0x14c5f)
    #4 0x55809e85d450 in gc_stack_roots::simple_collect() _gen/mycpp/examples/gc_stack_roots.mycpp.cc:122
    #5 0x55809e85df5a in gc_stack_roots::run_tests() _gen/mycpp/examples/gc_stack_roots.mycpp.cc:188
    #6 0x55809e85e03d in main _gen/mycpp/examples/gc_stack_roots.mycpp.cc:209
    #7 0x7f01aa35009a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
    #8 0x55809e85c7e9 in _start (/home/uke/oil/_bin/cxx-asan+gcalways/mycpp/examples/gc_stack_roots.mycpp+0x147e9)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/lib/x86_64-linux-gnu/libc.so.6+0x15bf30) 
==8767==ABORTING