FBRetainCycleDetector has a crash about fbretaincycledetector

[HGJiang]

FBRecycleTest`FB::RetainCycleDetector::Parser::Type::Type:
0x10448f70a <+0>: pushq %rbp
0x10448f70b <+1>: movq %rsp, %rbp
0x10448f70e <+4>: pushq %r15
0x10448f710 <+6>: pushq %r14
0x10448f712 <+8>: pushq %rbx
0x10448f713 <+9>: pushq %rax
0x10448f714 <+10>: movq %rdx, %r15
0x10448f717 <+13>: movq %rdi, %rbx
0x10448f71a <+16>: movq 0x791f(%rip), %rax ; (void *)0x000000010449b060: vtable for FB::RetainCycleDetector::Parser::Type
0x10448f721 <+23>: addq $0x10, %rax
0x10448f725 <+27>: movq %rax, (%rbx)
0x10448f728 <+30>: leaq 0x8(%rbx), %r14
0x10448f72c <+34>: movq %r14, %rdi
0x10448f72f <+37>: callq 0x1044926d8 ; symbol stub for: std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator >::basic_string(std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator > const&)
-> 0x10448f734 <+42>: leaq 0x20(%rbx), %rdi ;Thread 1: EXC_BAD_ACCESS (code=1, address=0x8)
0x10448f738 <+46>: movq %r15, %rsi
0x10448f73b <+49>: callq 0x1044926d8 ; symbol stub for: std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator >::basic_string(std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator > const&)
0x10448f740 <+54>: movq $0x0, 0x48(%rbx)
0x10448f748 <+62>: movq $0x0, 0x40(%rbx)
0x10448f750 <+70>: movq $0x0, 0x38(%rbx)
0x10448f758 <+78>: addq $0x8, %rsp
0x10448f75c <+82>: popq %rbx
0x10448f75d <+83>: popq %r14
0x10448f75f <+85>: popq %r15
0x10448f761 <+87>: popq %rbp
0x10448f762 <+88>: retq
0x10448f763 <+89>: movq %rax, %rbx
0x10448f766 <+92>: jmp 0x10448f773 ; <+105> at Type.h:25
0x10448f768 <+94>: movq %rax, %rbx
0x10448f76b <+97>: movq %r14, %rdi
0x10448f76e <+100>: callq 0x1044926e4 ; symbol stub for: std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator >::~basic_string()
0x10448f773 <+105>: movq %rbx, %rdi
0x10448f776 <+108>: callq 0x1044926b4 ; symbol stub for: _Unwind_Resume

[HGJiang]