-- in.cue --

// cycle is a structural cycle
cycle: a: cycle

// reference to outside structural cycle
r1a: cycle | int
r1b: int | cycle

r2a: cycle | 1
r2b: 1 | cycle

r3a: cycle | null
r3b: null | cycle

r4a: cycle | {}
r4b: {} | cycle

r5a: cycle | []
r5b: [] | cycle

// reference to ancestor node
s1a: x: s1a | int
s1b: x: int | s1b

s2a: x: s2a | 1
s2b: x: 1 | s2b

s3a: x: s3a | null
s3b: x: null | s3b

s4a: x: s4a | {}
s4b: x: {} | s4b

s5a: x: s5a | []
s5b: x: [] | s5b


-- out/eval --
Errors:
cycle.a: structural cycle

Result:
(_|_){
  // [structural cycle]
  cycle: (_|_){
    // [structural cycle]
    a: (_|_){
      // [structural cycle] cycle.a: structural cycle
      a: (_|_){// 〈1;cycle〉
      }
    }
  }
  r1a: (int){ int }
  r1b: (int){ int }
  r2a: (int){ 1 }
  r2b: (int){ 1 }
  r3a: (null){ null }
  r3b: (null){ null }
  r4a: (struct){
  }
  r4b: (struct){
  }
  r5a: (#list){
  }
  r5b: (#list){
  }
  s1a: (struct){
    x: (int){ int }
  }
  s1b: (struct){
    x: (int){ int }
  }
  s2a: (struct){
    x: (int){ 1 }
  }
  s2b: (struct){
    x: (int){ 1 }
  }
  s3a: (struct){
    x: (null){ null }
  }
  s3b: (struct){
    x: (null){ null }
  }
  s4a: (struct){
    x: (struct){
    }
  }
  s4b: (struct){
    x: (struct){
    }
  }
  s5a: (struct){
    x: (#list){
    }
  }
  s5b: (struct){
    x: (#list){
    }
  }
}
-- out/compile --
--- in.cue
{
  cycle: {
    a: 〈1;cycle〉
  }
  r1a: (〈0;cycle〉|int)
  r1b: (int|〈0;cycle〉)
  r2a: (〈0;cycle〉|1)
  r2b: (1|〈0;cycle〉)
  r3a: (〈0;cycle〉|null)
  r3b: (null|〈0;cycle〉)
  r4a: (〈0;cycle〉|{})
  r4b: ({}|〈0;cycle〉)
  r5a: (〈0;cycle〉|[])
  r5b: ([]|〈0;cycle〉)
  s1a: {
    x: (〈1;s1a〉|int)
  }
  s1b: {
    x: (int|〈1;s1b〉)
  }
  s2a: {
    x: (〈1;s2a〉|1)
  }
  s2b: {
    x: (1|〈1;s2b〉)
  }
  s3a: {
    x: (〈1;s3a〉|null)
  }
  s3b: {
    x: (null|〈1;s3b〉)
  }
  s4a: {
    x: (〈1;s4a〉|{})
  }
  s4b: {
    x: ({}|〈1;s4b〉)
  }
  s5a: {
    x: (〈1;s5a〉|[])
  }
  s5b: {
    x: ([]|〈1;s5b〉)
  }
}