[libcxx-commits] [libcxxabi] [libc++abi] Handle null pointer-to-object: Issue #64593 (PR #68076)

[Iain Sandoe via libcxx-commits]

iains wrote:

@mikeash , @rjmccall 

OK:
 * So I modified this now such that the function signatures are unchanged (the virtual base cookie is passed in the `__dynamic_cast_info` object instead).   The asm actually on ly mentions the function name - but I'm expecting that means 'mangled function name'.

* the additions to the `__dynamic_cast_info` are trailing so that a callee passed a pointer to an object, but that does not know about them would not be affected (I do not think this actually matters, in reality, it's just a bit of defensive programming)

@ldionne 

Thanks for the pointers.

I was unable to reproduce the asan fail on either x86_64 macOS 14 or arm64 macOS 12.7 - so I went ahead and made a conservative change - we will have to see if the problem clears on the bot.

The other cases are fixed (only testable on x86_64 AFAICT), I see some ld64 warnings about mismatched build versions on arm64 macOS 12,7 - and when the library is missing - we then get caught be the changes that mean there's no lib in `/usr/lib/` any more.

(we still expect the formatting complaints)


https://github.com/llvm/llvm-project/pull/68076