Type mismatch resolving `<OpaqueLayout_<PhantomData<&[u8]>> as CType>::OPAQUE_KIND == Concrete`

help
1

I tried using saffer-ffi 0.1.13 for generating C headers. Following the sample works without a problem. However, when attempting to add for the following function, it fails with errors for the code below

pub fn byte_pair_encode(piece: &[u8], ranks: &HashMap<Vec<u8>, Rank>) -> Vec<Rank> {
    if piece.len() == 1 {
        return vec![ranks[piece]];
    }
    _byte_pair_merge(ranks, piece)
        .windows(2)
        .map(|part| ranks[&piece[part[0].0..part[1].0]])
        .collect()
}

The error message

type mismatch resolving `<OpaqueLayout_<PhantomData<&[u8]>> as CType>::OPAQUE_KIND == Concrete`
required for `&[u8]` to implement `ConcreteReprC`

the trait bound `HashMap<std::vec::Vec<u8>, u32, BuildHasherDefault<FxHasher>>: ReprC` is not satisfied
the trait `ReprC` is implemented for `HashMap<K, V>`
required for `&HashMap<std::vec::Vec<u8>, u32, BuildHasherDefault<FxHasher>>` to implement `ReprC`
required for `&HashMap<std::vec::Vec<u8>, u32, BuildHasherDefault<FxHasher>>` to implement `ConcreteReprC`

type mismatch resolving `<OpaqueLayout_<PhantomData<Vec<u32>>> as CType>::OPAQUE_KIND == Concrete`
required for `std::vec::Vec<u32>` to implement `ConcreteReprC`

I kind of understand the trait ReprC is implemented for HashMap<K, V> , as the actual type K is Vec<?>, and V u32. But when checking the custom type page about hashmap, that page says Coming soon.

How can I solve those errors? Thanks.

2

Sounds like you cannot use HashMap with safer-ffi.

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