Clone issue on recursive, v1.0.0-alpha.4

[soywod]

Continuing my migration from v0.9.2 to v1.0.0-alpha.4, I cannot make the recursive work as before. So far here what I tried:

pub(crate) fn multi_part<'a>() -> impl Parser<'a, &'a str, Part, extra::Err<Rich<'a, char>>> {
    recursive(|multipart| {
        just(MULTI_PART_BEGIN)
            .ignore_then(
                choice((
                    multipart_type(),
                    #[cfg(feature = "pgp")]
                    encrypt(),
                    #[cfg(feature = "pgp")]
                    sign(),
                ))
                .repeated()
                .collect::<HashMap<String, String>>()
                .then_ignore(just(GREATER_THAN))
                .then_ignore(just(NEW_LINE).or_not()),
            )
            .then(
                choice((
                    multipart,
                    attachment(),
                    single_part(),
                    text_plain_part().map(Part::TextPlainPart),
                ))
                .repeated()
                .collect::<Vec<Part>>()
                .then_ignore(just(MULTI_PART_END))
                .then_ignore(just(NEW_LINE).or_not()),
            )
            .map(|(props, parts)| Part::MultiPart(props, parts))
    })
}

And here the error I get:

error[E0277]: the trait bound `impl chumsky::Parser<'_, &str, tokens::Part, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>: Clone` is not satisfied in `(Recursive<dyn chumsky::Parser<'_, &str, tokens::Part, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>>, impl chumsky::Parser<'_, &str, tokens::Part, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>, impl chumsky::Parser<'_, &str, tokens::Part, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>, chumsky::combinator::Map<impl chumsky::Parser<'_, &str, String, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>, String, fn(String) -> tokens::Part {tokens::Part::TextPlainPart}>)`
   --> mml/src/body/compiler/parsers/parts.rs:138:5
    |
138 |     recursive(|multipart| {
    |     ^^^^^^^^^ within `(Recursive<dyn chumsky::Parser<'_, &str, tokens::Part, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>>, impl chumsky::Parser<'_, &str, tokens::Part, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>, impl chumsky::Parser<'_, &str, tokens::Part, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>, chumsky::combinator::Map<impl chumsky::Parser<'_, &str, String, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>, String, fn(String) -> tokens::Part {tokens::Part::TextPlainPart}>)`, the trait `Clone` is not implemented for `impl chumsky::Parser<'_, &str, tokens::Part, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>`
    |
    = note: required because it appears within the type `(Recursive<dyn Parser<'_, &str, Part, Full<Rich<'_, char>, (), ()>>>, impl Parser<'_, &str, Part, Full<Rich<'_, char>, (), ()>>, impl Parser<'_, &str, Part, Full<Rich<'_, char>, (), ()>>, Map<impl Parser<'_, &str, String, Full<Rich<'_, char>, (), ()>>, String, fn(String) -> Part {Part::TextPlainPart}>)`
    = note: required for `Choice<(Recursive<dyn Parser<'_, &str, Part, Full<Rich<'_, char>, (), ()>>>, impl Parser<'_, &str, Part, ...>, ..., ...)>` to implement `Clone`
    = note: the full type name has been written to '/home/soywod/sourcehut/pimalaya/target/debug/deps/mml-3c223f74a7a7f669.long-type-12348717603651493785.txt'
    = note: 6 redundant requirements hidden
    = note: required for `Map<Then<IgnoreThen<Just<&str, &str, Full<Rich<'_, char, ..., ...>, ..., ...>>, ..., ..., ...>, ..., ..., ..., ...>, ..., ...>` to implement `Clone`
    = note: the full type name has been written to '/home/soywod/sourcehut/pimalaya/target/debug/deps/mml-3c223f74a7a7f669.long-type-8510872911944606774.txt'
note: required by a bound in `chumsky::recursive::recursive`
   --> /home/soywod/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.4/src/recursive.rs:271:30
    |
267 | pub fn recursive<'a, 'b, I, O, E, A, F>(f: F) -> Recursive<Direct<'a, 'b, I, O, E>>
    |        --------- required by a bound in this function
...
271 |     A: Parser<'a, I, O, E> + Clone + MaybeSync + 'b,
    |                              ^^^^^ required by this bound in `recursive`

error[E0277]: the trait bound `impl chumsky::Parser<'_, &str, (String, String), chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>: Clone` is not satisfied in `(impl chumsky::Parser<'_, &str, (String, String), chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>,)`
   --> mml/src/body/compiler/parsers/parts.rs:138:5
    |
138 |     recursive(|multipart| {
    |     ^^^^^^^^^ within `(impl chumsky::Parser<'_, &str, (String, String), chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>,)`, the trait `Clone` is not implemented for `impl chumsky::Parser<'_, &str, (String, String), chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>`
    |
    = note: required because it appears within the type `(impl Parser<'_, &str, (String, String), Full<Rich<'_, char>, (), ()>>,)`
    = note: required for `Choice<(impl chumsky::Parser<'_, &str, (String, String), chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>,)>` to implement `Clone`
    = note: 7 redundant requirements hidden
    = note: required for `Map<Then<IgnoreThen<Just<&str, &str, Full<Rich<'_, char, ..., ...>, ..., ...>>, ..., ..., ...>, ..., ..., ..., ...>, ..., ...>` to implement `Clone`
    = note: the full type name has been written to '/home/soywod/sourcehut/pimalaya/target/debug/deps/mml-3c223f74a7a7f669.long-type-8510872911944606774.txt'
note: required by a bound in `chumsky::recursive::recursive`
   --> /home/soywod/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.4/src/recursive.rs:271:30
    |
267 | pub fn recursive<'a, 'b, I, O, E, A, F>(f: F) -> Recursive<Direct<'a, 'b, I, O, E>>
    |        --------- required by a bound in this function
...
271 |     A: Parser<'a, I, O, E> + Clone + MaybeSync + 'b,
    |                              ^^^^^ required by this bound in `recursive`

error[E0277]: the trait bound `impl chumsky::Parser<'_, &str, String, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>: Clone` is not satisfied
   --> mml/src/body/compiler/parsers/parts.rs:138:5
    |
138 |     recursive(|multipart| {
    |     ^^^^^^^^^ the trait `Clone` is not implemented for `impl chumsky::Parser<'_, &str, String, chumsky::extra::Full<chumsky::error::Rich<'_, char>, (), ()>>`
    |
    = note: required for `Map<impl Parser<'_, &str, String, Full<Rich<'_, char>, (), ()>>, String, fn(String) -> Part {Part::TextPlainPart}>` to implement `Clone`
    = note: the full type name has been written to '/home/soywod/sourcehut/pimalaya/target/debug/deps/mml-3c223f74a7a7f669.long-type-17933626124731835590.txt'
    = note: required because it appears within the type `(Recursive<dyn Parser<'_, &str, Part, Full<Rich<'_, char>, (), ()>>>, impl Parser<'_, &str, Part, Full<Rich<'_, char>, (), ()>>, impl Parser<'_, &str, Part, Full<Rich<'_, char>, (), ()>>, Map<impl Parser<'_, &str, String, Full<Rich<'_, char>, (), ()>>, String, fn(String) -> Part {Part::TextPlainPart}>)`
    = note: required for `Choice<(Recursive<dyn Parser<'_, &str, Part, Full<Rich<'_, char>, (), ()>>>, impl Parser<'_, &str, Part, ...>, ..., ...)>` to implement `Clone`
    = note: the full type name has been written to '/home/soywod/sourcehut/pimalaya/target/debug/deps/mml-3c223f74a7a7f669.long-type-12348717603651493785.txt'
    = note: 6 redundant requirements hidden
    = note: required for `Map<Then<IgnoreThen<Just<&str, &str, Full<Rich<'_, char, ..., ...>, ..., ...>>, ..., ..., ...>, ..., ..., ..., ...>, ..., ...>` to implement `Clone`
    = note: the full type name has been written to '/home/soywod/sourcehut/pimalaya/target/debug/deps/mml-3c223f74a7a7f669.long-type-8510872911944606774.txt'
note: required by a bound in `chumsky::recursive::recursive`
   --> /home/soywod/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.4/src/recursive.rs:271:30
    |
267 | pub fn recursive<'a, 'b, I, O, E, A, F>(f: F) -> Recursive<Direct<'a, 'b, I, O, E>>
    |        --------- required by a bound in this function
...
271 |     A: Parser<'a, I, O, E> + Clone + MaybeSync + 'b,
    |                              ^^^^^ required by this bound in `recursive`

[wackbyte]

The error is occuring because recursive requires the parser it contains to implement Clone, but impl Parser is an opaque type that only implements Parser and not Clone. Therefore, the solution is likely to add + Clone to the return type of all the other parsers you use in this function (multipart_type(), encrypt(), etc.).

[soywod]

Thank you, it worked as expected!