Support function pointer type about libffi-rs HOT 3 OPEN

@Phosra Out of curiosity, on what platforms would this be unsound?

Admittedly, such platform would likely be a Harvard architecture platform that doesn't implement POSIX - in practice... it's very unlikely to encounter such a platform, even less so for one with different sizes.

Although, it's possible to find maybe a Harvard embedded platform? How that could possibly affect FFI, I suppose it could be useful for interacting with native code after developing and running a new scripting language compiled as a bytecode, such as is done for JavaScript via XS, or Python via CircuitPython.

More realistically, although I cannot quite determine whether it's so, but a (future) CHERI Aarch64 Harvard, platform running an OS that doesn't implement POSIX could run into such an issue... still amusingly unlikely!

It's more of a "technical" issue. :)

from libffi-rs.

@Phosra Out of curiosity, on what platforms would this be unsound?

from libffi-rs.