[libcxx-commits] [libcxx] [libc++] Add an ABI setting to harden unique_ptr<T[]>::operator[] (PR #91798)

[Eli Friedman via libcxx-commits]

efriedma-quic wrote:

https://itanium-cxx-abi.github.io/cxx-abi/abi.html#array-cookies describes array cookies.  If the cookie is present, I can't think of any reason it would be a problem for libc++ to read it.

If the cookie isn't present, though, we can't access it, and forcing the compiler to generate a cookie where it normally wouldn't generate one is ABI break.

https://github.com/llvm/llvm-project/pull/91798