offset_of! is unsound

[kazcw]

siege-render/src/vertex.rs

Line 8 in cb56a00

macro_rules! offset_of {

All uses of offset_of invoke UB. There's no fix until RFC 2582 is implemented. From the RFC:

references must be aligned and dereferencable, even when they are created and never used.

[mikedilger]

Wow, thanks, that's subtle.

Out of curiousity, are you using Siege Engine or did you find this with some sort of code scan? It's a code dump in a sorry and unmaintained state IMHO because I didn't think anybody was using it.

[kazcw]

Just a search. I came across a sketchy offset_of macro somewhere else; after I determined that there was no legal way to implement a macro like that, I searched github for other uses of that name in Rust code. This repo came up near the top.