-- in.cue --
#schema: a!: bool
_hidden & #schema // must fail here, but not elsewhere
_hidden: {
	"a":        true
	notAllowed: true
}
allowed: true
-- out/compile --
--- in.cue
{
  #schema: {
    a!: bool
  }
  (〈0;_hidden〉 & 〈0;#schema〉)
  _hidden: {
    a: true
    notAllowed: true
  }
  allowed: true
}
