是否有任何 C++ 编译器可以针对悬空引用发出警告？

给出以下代码，其中x是一个悬空的const reference到一个消失的对象，因此是未定义的行为。

auto get_vec() { return std::vector<int>{1,2,3,4,5}; }
const auto& x = get_vec().back();

似乎两者都不是GCC 7.3, 铿锵6.0 and MSVC即使启用了所有警告，也能够发出警告。 有谁知道在这些情况下是否有办法发出警告？ 有什么区别吗const auto& and auto&&在这些情况下？

注意，如果back()将按值返回，这不会是未定义的行为，因为生命周期临时对象 x 已扩展为函数 scoop。

长话短说：我有一个代码库，其中const auto&被用作初始化变量的默认方式，并且出于某种奇怪的原因，这些情况使用 MSVC 正确执行，但是当使用 Android 版 Clang 编译时，每次出现都会导致错误的赋值。目前，解决方案似乎正在调查每一个const auto&在整个代码库中。 而且，在很多情况下const auto&指的是通过引用返回的重对象，因此只需删除&不是一个解决方案。

还有一件事，我要为滥用行为负责const auto& :)

我现在唯一能想到的就是将 CLANG 与 -fsanitize=address 一起使用。当然，这只会在运行时有帮助，但随后你会得到像这样的好东西：

==102554==ERROR: AddressSanitizer: heap-use-after-free on address 0x603000000020 at pc 0x00000050db71 bp 0x7ffdd3a5b770 sp 0x7ffdd3a5b768
READ of size 4 at 0x603000000020 thread T0
    #0 0x50db70 in main (/home/user/testDang+0x50db70)
    #1 0x1470fb404889 in __libc_start_main (/lib64/libc.so.6+0x20889)
    #2 0x41a019 in _start (/home/user/testDang+0x41a019)

0x603000000020 is located 16 bytes inside of 20-byte region [0x603000000010,0x603000000024)
freed by thread T0 here:
    #0 0x50a290 in operator delete(void*) (/home/user/testDang+0x50a290)
    #1 0x50eccf in __gnu_cxx::new_allocator<int>::deallocate(int*, unsigned long) (/home/user/testDang+0x50eccf)
    #2 0x50ec9f in std::allocator_traits<std::allocator<int> >::deallocate(std::allocator<int>&, int*, unsigned long) (/home/user/testDang+0x50ec9f)
    #3 0x50ec2a in std::_Vector_base<int, std::allocator<int> >::_M_deallocate(int*, unsigned long) (/home/user/testDang+0x50ec2a)
    #4 0x50e577 in std::_Vector_base<int, std::allocator<int> >::~_Vector_base() (/home/user/testDang+0x50e577)
    #5 0x50e210 in std::vector<int, std::allocator<int> >::~vector() (/home/user/testDang+0x50e210)
    #6 0x50db16 in main (/home/user/testDang+0x50db16)
    #7 0x1470fb404889 in __libc_start_main (/lib64/libc.so.6+0x20889)

previously allocated by thread T0 here:
    #0 0x509590 in operator new(unsigned long) (/home/user/testDang+0x509590)
    #1 0x50e9ab in __gnu_cxx::new_allocator<int>::allocate(unsigned long, void const*) (/home/user/testDang+0x50e9ab)
    #2 0x50e94b in std::allocator_traits<std::allocator<int> >::allocate(std::allocator<int>&, unsigned long) (/home/user/testDang+0x50e94b)
    #3 0x50e872 in std::_Vector_base<int, std::allocator<int> >::_M_allocate(unsigned long) (/home/user/testDang+0x50e872)
    #4 0x50e2ff in void std::vector<int, std::allocator<int> >::_M_range_initialize<int const*>(int const*, int const*, std::forward_iterator_tag) (/home/user/testDang+0x50e2ff)
    #5 0x50deb7 in std::vector<int, std::allocator<int> >::vector(std::initializer_list<int>, std::allocator<int> const&) (/home/user/testDang+0x50deb7)
    #6 0x50dafb in main (/home/user/testDang+0x50dafb)
    #7 0x1470fb404889 in __libc_start_main (/lib64/libc.so.6+0x20889)

SUMMARY: AddressSanitizer: heap-use-after-free (/home/user/testDang+0x50db70) in main
Shadow bytes around the buggy address:
  0x0c067fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c067fff8000: fa fa fd fd[fd]fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb

也许您有自动化的单元测试，可以轻松地作为“sanizizer”构建运行。