co3 0.4.0

Build C API from Rust
Documentation 
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use co3::{Tag, ReprC, ffi, rust_spec::RustSpec};

#[derive(RustSpec, Tag, ReprC)]
#[tag(u8, unsafe(1))]
#[repr(transparent)]
struct Attribute(u32);

#[derive(RustSpec, ReprC)]
#[repr(C)]
struct Prefix<T: ?Sized> {
    head: u32,
    tail: T,
}

fn prefix_head<T: ?Sized>(prefix: &Prefix<T>) -> u32 {
    prefix.head
}

ffi! {
    #![unsafe(export("C"))]

    #[symbol_name = "dispatch_opaque_tail_head"]
    fn prefix_head<'a, dyn(u8) T: ?Sized>(prefix: &'a Prefix<T>) -> u32
    where
        use<T> @ <Attribute>;
}

ffi! {
    #![unsafe(extern("C"))]

    #[symbol_name = "dispatch_opaque_tail_head"]
    fn imported_prefix_head<'a, dyn(u8) T: ?Sized>(
        tag_id: <dyn T>::TAG,
        prefix: &'a Prefix<T>,
    ) -> u32
    where
        use<T> @ <Attribute>;
}

fn main() {
    let prefix = Box::leak(Box::new(Prefix {
        head: 7,
        tail: Attribute(9),
    }));

    assert_eq!(imported_prefix_head(prefix), 7);
}