enum & allOf

https://github.com/discord/discord-api-spec/blob/main/specs/openapi.json contains a lot of schemas like this.

    RoleSelectDefaultValueResponse:
      type: object
      properties:
        type:
          type: string
          enum:
          - role
          allOf:
          - $ref: '#/components/schemas/SnowflakeSelectDefaultValueTypes'
        id:
          $ref: '#/components/schemas/SnowflakeType'
      required:
      - type
      - id
...
    SnowflakeSelectDefaultValueTypes:
      type: string
      oneOf:
      - title: USER
        const: user
      - title: ROLE
        const: role
      - title: CHANNEL
        const: channel

Note I am using https://github.com/sciguy16/openapi31to30 to make it compatible with progenitor/typify

I checked the openapi doc using https://github.com/daveshanley/vacuum , and while there were a lot of warnings, they didnt appear to relate to the above https://github.com/discord/discord-api-spec/issues/41

I don't see any prohibition on using enum & allOf in this way...?
As I understand it, the addition of allOf SnowflakeSelectDefaultValueTypes is redundant, as SnowflakeSelectDefaultValueTypes is a superset of the enum, and could be simply discarded.

typify on main fails at https://github.com/oxidecomputer/typify/blob/7d61436/typify-impl/src/defaults.rs#L320

  thread 'main' panicked at /Users/jayvdb/rust/typify/typify-impl/src/defaults.rs:320:47:
  internal error: entered unreachable code
  stack backtrace:
     0: __rustc::rust_begin_unwind
               at /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/std/src/panicking.rs:697:5
     1: core::panicking::panic_fmt
               at /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/core/src/panicking.rs:75:14
     2: core::panicking::panic
               at /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/core/src/panicking.rs:145:5
     3: typify_impl::defaults::<impl typify_impl::type_entry::TypeEntry>::validate_value
     4: typify_impl::convert::<impl typify_impl::TypeSpace>::convert_typed_enum::{{closure}}
     5: core::iter::traits::iterator::Iterator::try_for_each::call::{{closure}}
     6: core::iter::traits::iterator::Iterator::try_fold
     7: core::iter::traits::iterator::Iterator::try_for_each
     8: typify_impl::convert::<impl typify_impl::TypeSpace>::convert_typed_enum
     9: typify_impl::convert::<impl typify_impl::TypeSpace>::convert_schema_object
    10: typify_impl::convert::<impl typify_impl::TypeSpace>::convert_schema
    11: typify_impl::TypeSpace::id_for_schema
    12: typify_impl::structs::<impl typify_impl::TypeSpace>::struct_property
    13: typify_impl::structs::<impl typify_impl::TypeSpace>::struct_members::{{closure}}
    14: core::iter::adapters::filter_map::filter_map_try_fold::{{closure}}
    15: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
    16: core::iter::traits::iterator::Iterator::try_fold
    17: <core::iter::adapters::chain::Chain<A,B> as core::iter::traits::iterator::Iterator>::try_fold
    18: <core::iter::adapters::filter_map::FilterMap<I,F> as core::iter::traits::iterator::Iterator>::try_fold
    19: <core::iter::adapters::GenericShunt<I,R> as core::iter::traits::iterator::Iterator>::try_fold
    20: <core::iter::adapters::GenericShunt<I,R> as core::iter::traits::iterator::Iterator>::next
    21: alloc::vec::Vec<T,A>::extend_desugared
    22: <alloc::vec::Vec<T,A> as alloc::vec::spec_extend::SpecExtend<T,I>>::spec_extend
    23: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter_nested::SpecFromIterNested<T,I>>::from_iter
    24: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
    25: <alloc::vec::Vec<T> as core::iter::traits::collect::FromIterator<T>>::from_iter
    26: core::iter::traits::iterator::Iterator::collect
    27: <core::result::Result<V,E> as core::iter::traits::collect::FromIterator<core::result::Result<A,E>>>::from_iter::{{closure}}
    28: core::iter::adapters::try_process
    29: <core::result::Result<V,E> as core::iter::traits::collect::FromIterator<core::result::Result<A,E>>>::from_iter
    30: core::iter::traits::iterator::Iterator::collect
    31: typify_impl::structs::<impl typify_impl::TypeSpace>::struct_members
    32: typify_impl::convert::<impl typify_impl::TypeSpace>::convert_object
    33: typify_impl::convert::<impl typify_impl::TypeSpace>::convert_schema_object
    34: typify_impl::convert::<impl typify_impl::TypeSpace>::convert_schema
    35: typify_impl::TypeSpace::convert_ref_type
    36: typify_impl::TypeSpace::add_ref_types_impl
    37: typify_impl::TypeSpace::add_ref_types
    38: progenitor_impl::Generator::generate_tokens

Start with typify-impl/src/defaults.rs around line 320, then follow the convert_typed_enum and convert_schema_object frames in the reported backtrace. Reproduce generation using the linked Discord OpenAPI schema and the sciguy16/openapi31to30 conversion. Done means enum combined with allOf no longer reaches the unreachable panic and the schema is handled consistently.