As described in https://github.com/llvm/llvm-project/issues/69994, using the escape hatch makes us non-conforming in C++20. There are other problems like https://github.com/llvm/llvm-project/issues/63900. We discussed this in the libc++ monthly meeting today and agreed that we should deprecate the macro in LLVM 18 and remove it in LLVM 19.
