Macro ghosts::ghost

macro_rules! ghost {
    ( $($_:tt)* ) => { ... };
    (
        $( #[tag($meta:meta)] )?
        $( #[no_init] )?
        $( |$ghost_ctx:pat| )?
        $expr_or_block:expr
    ) => { ... };
}

Ghost expressions. PhantomCode of sorts, if you want.

See the main docs for more info.

Examples

? and .await work inside it.

use ::ghosts::vestibule::*;

fn main ()
 -> ::std::io::Result<()>
{
   let casper = ghost!({
       let foo = ::std::fs::File::open("/the/door")?;
   });
   async {
       let in_the_shell = ghost!({
           let bar = example().await;
       });
   };
   Ok(())
}

async
fn example ()
{
   // …
}

break and continue work inside it, provided they be labelled.

use ::ghosts::vestibule::*;

let _: i32 = 'labelled: loop {
   let casper = ghost!({
       break 'labelled 42;
   });
   break 0;
};

ghost! expressions consume ownership of their captures…

use ::ghosts::vestibule::*;

let owned = String::from("…");
let casper = ghost!(owned);
drop(owned); // Error, use of moved value

• (note: once in the Ghost Realm™, things stay there. There is no way for ownership relinquished over the Ghost Realm™ to ever be claimed back outside of it)

… unless the #[no_init] opt-out is used

use ::ghosts::vestibule::*;

let owned = String::from("…");
let casper = ghost!(#[no_init] {
   owned
});
drop(owned); // Ok