Wishlist: Blocked on upstream changes

[jonasbb]

• MSRV Rust 1.64:

  • Use workspace.package and workspace.dependencies. The main advantage is sharing the metadata between the related packages. The slightly simpler dependency management is a bonus.

• MSRV Rust 1.88:

  • Replace cfg(all()) and cfg(any()) with cfg(true) and cfg(false)

• feature(adt_const_params)

  • Add extra layers for serializing/deserializing. https://github.com/jonasbb/serde_with/issues/340#issuecomment-961492301

    ![feature(adt_const_params)]
    
    [derive(Copy, Clone, Debug, Default)]
    ub struct Layer<const FIELD: &'static str, T: ?Sized>(T);
    
    mpl<const FIELD: &'static str, T, U> SerializeAs<T> for Layer<FIELD, U>
    here
       U: SerializeAs<T>,
       T: ?Sized,
       U: ?Sized,
    
       fn serialize_as<S>(source: &T, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
           use serde::ser::SerializeStruct;
    
           let mut ser_struct = serializer.serialize_struct("Layer", 1)?;
           ser_struct.serialize_field(FIELD, &ser::SerializeAsWrap::<T, U>::new(source))?;
           ser_struct.end()
       }
    
    
    / Can be used like this
    [serde_as]
    [derive(Serialize)]
    truct Data {
       i: i32,
       #[serde_as(as = r#"Layer<"extra", Layer<"foobar", Layer<"really_another_one", DisplayFromStr>>>"#)]
       b: bool,
    
    
    / or like
    erde_json::to_string(&Layer::<"root">(&data))
    

    https://github.com/dtolnay/monostate contains a solution to encode &str into a static type without requiring adt_const_params. It doesn't quite fit the above use case, since the value is not accessible as a &'static str. But Layer could be implemented if it uses serialize_map.

  • Add a macro-free version of with_prefix!.

  • Get rid of the special key name requirement for `KeyValueMap https://github.com/jonasbb/serde_with/blob/725d177fdf66583fc234ca07e2ec8df4a03c1aa4/serde_with/src/key_value_map.rs#L210-L215

• feature(array_try_from_fn) https://github.com/rust-lang/rust/issues/89379

  • Replace the unsafe implementation of array_from_iterator with something from std. https://github.com/rust-lang/rust/issues/81615 https://github.com/jonasbb/serde_with/blob/b50b611b690aeb2747030b90b7c10e921ffb2ec4/serde_with/src/utils.rs#L119-L174

• Use workspace lints with separate overrides per crate: https://github.com/rust-lang/cargo/issues/13157

• feature(core_float_math) https://github.com/rust-lang/rust/issues/137578 https://github.com/jonasbb/serde_with/blob/be794b7f89683f1adc9e508f199f0822267f2d47/serde_with/src/utils/duration.rs#L389-L399

  Currently, for deserializing Durations as f64 the values are rounded. The round() function is only available in std, thus the implementations must be gated. Writing a rounding function that works well for all f64 values is also not trivial.