Unable to render schema with recursive type that requires oneOf directive

[annad-at-tapad]

Minimally reproduced in this Scastie (which is modified from @ghostdogpr 's Scastie in our chat in Discord around this topic to account for the rules required for @oneOf: (1) the leaf case class must contain exactly 1 non-nullable field, (2) the field names in the leaf cases must be unique, and (3) any objects used in the leaf cases must have a Schema and an ArgBuilder).

Just in case there's some issue with accessing the Scastie content, I'm leaving the code snippet here as well:

import caliban.schema.Annotations.GQLOneOfInput
import caliban.schema.{ArgBuilder, Schema}

//@GQLOneOfInput
sealed trait Clause derives Schema.SemiAuto, ArgBuilder

case class SimpleClause(col: String) extends Clause derives Schema.SemiAuto, ArgBuilder
case class And (andClauses: Seq[Clause]) extends Clause derives Schema.SemiAuto, ArgBuilder
case class Or (orClauses: Seq[Clause]) extends Clause derives Schema.SemiAuto, ArgBuilder

case class Args(clause: Clause) derives Schema.SemiAuto, ArgBuilder
case class Query(test: Args => Int) derives Schema.SemiAuto


println(caliban.render[Query])

If I commented out the @GQLOneOfInput directive, the schema is rendered successfully as:

union Clause = And | Or | SimpleClause

type And {
  andClauses: [Clause!]!
}

type Or {
  orClauses: [Clause!]!
}

type Query {
  test(clause: Clause!): Int!
}

type SimpleClause {
  col: String!
}

However, with the directive, the code does not terminate.

[annad-at-tapad]

@ghostdogpr A colleague of mine came up with a workaround; I'm documenting it here as it may help others in the same situation:

import caliban.schema.Annotations.GQLOneOfInput
import caliban.schema.{ArgBuilder, Schema}

@GQLOneOfInput
sealed trait Clause derives Schema.SemiAuto, ArgBuilder

case class SimpleClause(col: String, v: String) derives Schema.SemiAuto, ArgBuilder
case class AndClauses(and: Seq[Clause]) derives Schema.SemiAuto, ArgBuilder
case class OrClauses(or: Seq[Clause]) derives Schema.SemiAuto, ArgBuilder

case class Simple(simpleClause: SimpleClause) extends Clause derives Schema.SemiAuto, ArgBuilder
case class And (andClauses: AndClauses) extends Clause derives Schema.SemiAuto, ArgBuilder
case class Or (orClauses: OrClauses) extends Clause derives Schema.SemiAuto, ArgBuilder

case class Args(clause: Clause) derives Schema.SemiAuto, ArgBuilder
case class Query(test: Args => Int) derives Schema.SemiAuto

println(caliban.render[Query])

This yields the following schema:

input AndClausesInput {
  and: [ClauseInput!]!
}

input ClauseInput @oneOf {
  andClauses: AndClausesInput
  orClauses: OrClausesInput
  simpleClause: SimpleClauseInput
}

input OrClausesInput {
  or: [ClauseInput!]!
}

input SimpleClauseInput {
  col: String!
  v: String!
}

type Query {
  test(clause: ClauseInput!): Int!
}