-- in.cue --
// Allow lookup in partially evaluated struct as long as the end result is
// concrete.
A: {
    a: {
        parent: ""
        children: [ for k, v in A if v.parent == k { k } ]
    }
    b: {
        parent: "a"
        children: [ for k, v in A if v.parent == k { k } ]
    }
}

// This should result in an incomplete error (a reference cycle error classifies
// as incomplete).
B: {
    a: {
        parent: ""
        children: [ for k, v in B for _, w in v.children { k } ]
    }
}

// Issue #486
Issue486: {
    A: {
        a: {
            parent: ""
            children: [...string]
        }
        b: {
            parent: "a"
            children: [...string]
        }
        c: {
            parent: "b"
            children: [...string]
        }
    }

    A: [Name=string]: {
        children: [
            for k, v in A
            if v.parent == Name {
                k
            }
        ]
    }
}
-- out/eval --
(struct){
  A: (struct){
    a: (struct){
      parent: (string){ "" }
      children: (#list){
      }
    }
    b: (struct){
      parent: (string){ "a" }
      children: (#list){
      }
    }
  }
  B: (struct){
    a: (struct){
      parent: (string){ "" }
      children: (_|_){
        // [cycle] cycle error:
        //     ./in.cue:19:47
      }
    }
  }
  Issue486: (struct){
    A: (struct){
      a: (struct){
        parent: (string){ "" }
        children: (#list){
          0: (string){ "b" }
        }
      }
      b: (struct){
        parent: (string){ "a" }
        children: (#list){
          0: (string){ "c" }
        }
      }
      c: (struct){
        parent: (string){ "b" }
        children: (#list){
        }
      }
    }
  }
}
-- out/compile --
--- in.cue
{
  A: {
    a: {
      parent: ""
      children: [
        for k, v in 〈2;A〉 if (〈0;v〉.parent == 〈0;k〉) {
          〈1;k〉
        },
      ]
    }
    b: {
      parent: "a"
      children: [
        for k, v in 〈2;A〉 if (〈0;v〉.parent == 〈0;k〉) {
          〈1;k〉
        },
      ]
    }
  }
  B: {
    a: {
      parent: ""
      children: [
        for k, v in 〈2;B〉 for _, w in 〈0;v〉.children {
          〈2;k〉
        },
      ]
    }
  }
  Issue486: {
    A: {
      a: {
        parent: ""
        children: [
          ...string,
        ]
      }
      b: {
        parent: "a"
        children: [
          ...string,
        ]
      }
      c: {
        parent: "b"
        children: [
          ...string,
        ]
      }
    }
    A: {
      [string]: {
        children: [
          for k, v in 〈2;A〉 if (〈0;v〉.parent == 〈2;-〉) {
            〈1;k〉
          },
        ]
      }
    }
  }
}