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//! What the derive macros refuse, each as a doctest that must not compile. The
//! module exists only while rustdoc collects doctests.
/// An event needs its event type:
///
/// ```compile_fail
/// #[derive(serde::Serialize, serde::Deserialize, architecturekit::Event)]
/// struct BookAcquired {
/// title: String,
/// }
/// ```
///
/// And the event type must not be empty:
///
/// ```compile_fail
/// #[derive(serde::Serialize, serde::Deserialize, architecturekit::Event)]
/// #[event(type = "")]
/// struct BookAcquired {
/// title: String,
/// }
/// ```
;
/// serde writes an enum in several shapes:
///
/// ```compile_fail
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// enum Format {
/// Hardcover,
/// Paperback,
/// }
/// ```
;
/// serde writes a unit struct as null:
///
/// ```compile_fail
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// struct Marker;
/// ```
;
/// serde writes a tuple struct with several fields as an array of mixed values:
///
/// ```compile_fail
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// struct Range(i64, String);
/// ```
;
/// serde writes a transparent struct as its only field:
///
/// ```compile_fail
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// #[serde(transparent)]
/// struct Pages {
/// count: i64,
/// unit: String,
/// }
/// ```
;
/// serde writes the fields of a flattened field in place of the field:
///
/// ```compile_fail
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// struct Audit {
/// by: String,
/// }
///
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// struct Book {
/// title: String,
/// #[serde(flatten)]
/// audit: Audit,
/// }
/// ```
;
/// A field that serde writes with a function of its own is not written as its
/// type describes:
///
/// ```compile_fail
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// struct Book {
/// #[serde(serialize_with = "serialize_pages")]
/// pages: i64,
/// }
///
/// fn serialize_pages<S: serde::Serializer>(pages: &i64, serializer: S) -> Result<S::Ok, S::Error> {
/// serializer.serialize_str(&pages.to_string())
/// }
/// ```
;
/// serde writes a struct with a tag with a further field:
///
/// ```compile_fail
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// #[serde(tag = "kind")]
/// struct Book {
/// title: String,
/// }
/// ```
;
/// serde writes a struct with `into` as the other type:
///
/// ```compile_fail
/// #[derive(Clone, serde::Serialize, architecturekit::Schema)]
/// #[serde(into = "String")]
/// struct Isbn {
/// digits: String,
/// }
///
/// impl From<Isbn> for String {
/// fn from(isbn: Isbn) -> Self {
/// isbn.digits
/// }
/// }
/// ```
;
/// The events of a state are an enum, with one variant per event type:
///
/// ```compile_fail
/// #[derive(architecturekit::Events)]
/// struct BookEvent {
/// title: String,
/// }
/// ```
///
/// And every variant holds exactly one event:
///
/// ```compile_fail
/// #[derive(serde::Serialize, serde::Deserialize, architecturekit::Event)]
/// #[event(type = "io.eventsourcingdb.library.book-acquired")]
/// struct BookAcquired {
/// title: String,
/// }
///
/// #[derive(architecturekit::Events)]
/// enum BookEvent {
/// Acquired(BookAcquired),
/// Lost,
/// }
/// ```
///
/// ```compile_fail
/// #[derive(serde::Serialize, serde::Deserialize, architecturekit::Event)]
/// #[event(type = "io.eventsourcingdb.library.book-acquired")]
/// struct BookAcquired {
/// title: String,
/// }
///
/// #[derive(architecturekit::Events)]
/// enum BookEvent {
/// Acquired { event: BookAcquired },
/// }
/// ```
;
/// Two variants of the same event type would make reading ambiguous:
///
/// ```compile_fail
/// #[derive(serde::Serialize, serde::Deserialize, architecturekit::Event)]
/// #[event(type = "io.eventsourcingdb.library.book-acquired")]
/// struct BookAcquired {
/// title: String,
/// }
///
/// #[derive(serde::Serialize, serde::Deserialize, architecturekit::Event)]
/// #[event(type = "io.eventsourcingdb.library.book-acquired")]
/// struct BookBought {
/// title: String,
/// }
///
/// #[derive(architecturekit::Events)]
/// enum BookEvent {
/// Acquired(BookAcquired),
/// Bought(BookBought),
/// }
/// ```
;
/// The variants of an enum of events name the event types of a state, so it
/// can not be generic:
///
/// ```compile_fail
/// #[derive(architecturekit::Events)]
/// enum Wrapped<T: architecturekit::Event> {
/// Event(T),
/// }
/// ```
;
/// A field needs a type that describes its schema:
///
/// ```compile_fail,E0277
/// #[derive(serde::Serialize)]
/// struct Address {
/// city: String,
/// }
///
/// #[derive(serde::Serialize, architecturekit::Schema)]
/// struct Reader {
/// address: Address,
/// }
/// ```
;