[sundermann]

Fixes CONVERT_DYNAMIC_TO_CHOICE exposing abstract schema types and elements as constructible enum variants.

Changes

• Exclude abstract descendants and substitution-group members while retaining concrete descendants, including leaves beneath abstract intermediate types.
• Filter only the choice being converted, preserving unconverted dynamic types and their boxed-dyn trait implementations and supertraits. Cache abstract identifiers before conversion to keep individual, bulk, and mixed conversions independent of order.
• Represent types without concrete alternatives as uninhabited types, including XML serialization and deserialization in flattened and wrapped layouts.
• Preserve element names, namespaces, and root state through unflattened dynamic content. Wrappers pass caller context unchanged; their content enum chooses the caller's name for type-identified alternatives or the schema's substitution tag.
• Add an XSD fixture and compiled type and quick-xml snapshots with and without FLATTEN_CONTENT, with unreachable_code denied. Cover nested and standalone concrete XML round trips, rejection of abstract tags and types, and empty choices. Metadata regressions cover conversion order and preserving unconverted dynamic types.
• Omit unused root context and helper parameter bindings from empty-enum XML implementations. Keep snapshot-covered assertions in the compiled fixtures rather than duplicate token-string tests, and leave the release changelog unchanged.

Generated API changes: enums lose invalid abstract variants, and abstract types without concrete descendants can no longer be instantiated as empty structs. A required field of an uninhabited type also makes its containing type impossible to construct.

Checklist

• Tests for the change (a bug fix has a test that fails without the fix)
• Changed snapshots are regenerated with update-expectations and reviewed
• cargo fmt, cargo clippy and cargo test pass (see CONTRIBUTING.md)
• cargo build -p benchmark --release and release runs of read_write, bpmn, and vsme pass
• Breaking changes of the public API or the generated code are described above

[Bergmann89]

Hey @sundermann,

Thanks, the core fix looks right to me: abstract complex types and abstract elements are both caught, concrete leaves under an abstract intermediate survive, and computing the abstract set up front really makes the conversion order-independent. The onix snapshot changes are all explained by the removed abstract XHTML heads.

A few things before merging:

• Missing test for the generated serializer/deserializer. The new tests use Config::test_default(), which only renders the types, so the quick_xml code for the new empty enums is never generated or compiled. In the flattened case next_event renders match *self.value {} followed by more code, which will most likely trigger unreachable_code. Please add a feature test under tests/feature/ with schema.xsd + compiled expected/default.rs / expected/quick_xml.rs, with and without FLATTEN_CONTENT, plus a read test that a concrete member round-trips and an abstract tag is rejected.
• Converting a single type affects other dynamic types. remove_abstract_derived_types (dynamic_to_choice.rs) strips abstract entries from every dynamic type, not just the one being converted. For a type that stays dynamic, this drops trait impls and supertraits from the boxed-dyn output. Please touch only the types being converted.

Nits: add an empty /// line before the new doc lines in dynamic_to_choice.rs:20, and the comment at complex.rs:292 mostly repeats the condition.

[sundermann]

@Bergmann89 Thanks! I revisited the PR and adressed the feedback, should be good now

[Bergmann89]

Thanks, that looks great now! The new feature test with the read tests is exactly what I was looking for, and the conversion only touches the converted types now.

I added the last small things as suggestions, then it's ready to merge.