Soundness issue when borrowing Lua in a callback

[kyren]

Currently this compiles, and that is a problem because lua does not have a stable address. Closures should go back to having a 'static lifetime.

    let lua = Lua::new();
    let globals = lua.globals();

    globals.set("boom", lua.create_function(|_, _| {
        lua.pack(lua.eval::<i32>("1 + 1", None)?)
    })).unwrap();

[jonas-schievink]

Just to clarify: This example in itself is still fine, the issue is that the borrow of lua isn't tracked by Rust, allowing code to move it while it's still borrowed: Doing let moved = lua; after the code above would compile (after a bit of restructuring) and lead to a dangling pointer deref when the function is called.

[kyren]

Thanks for the clarification, that is exactly right. This is discussed further in #32 for anybody following along, but we should probably discuss it further here.

So, the proposed solution is simply to move callbacks back to 'static lifetime, and I don't see really any other way of solving this, but it sounds like you might have some ideas?

[jonas-schievink]

Let's go back to 'static for now. Should I feel very motivated I might search for a better solution, but I don't think that's happening anytime soon.