AddressSanitizer:DEADLYSIGNAL
=================================================================
==8658==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000008 (pc 0x7fa1409fdf31 bp 0x000000000008 sp 0x7ffe14912098 T0)
==8658==The signal is caused by a READ memory access.
==8658==Hint: address points to the zero page.
    #0 0x7fa1409fdf30  (/lib/x86_64-linux-gnu/libc.so.6+0x15bf30)
    #1 0x7fa1409125d4 in fputs (/lib/x86_64-linux-gnu/libc.so.6+0x705d4)
    #2 0x5563ddbac8fa in print(BigStr*) mycpp/gc_builtins.cc:14
    #3 0x5563ddba9af0 in gc_stack_roots::collect_in_loop() (/home/uke/oil/_bin/cxx-asan+gcalways/mycpp/examples/gc_stack_roots.mycpp+0x16af0)
    #4 0x5563ddba9c74 in gc_stack_roots::run_tests() (/home/uke/oil/_bin/cxx-asan+gcalways/mycpp/examples/gc_stack_roots.mycpp+0x16c74)
    #5 0x5563ddba9d43 in main (/home/uke/oil/_bin/cxx-asan+gcalways/mycpp/examples/gc_stack_roots.mycpp+0x16d43)
    #6 0x7fa1408c609a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
    #7 0x5563ddba77e9 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) 
==8658==ABORTING