-- in.cue --
import "struct"

minFields: {
	[string]: struct.MinFields(1)

	incomplete1: {}
	fail1: close({})
	ok1: {a: 1}
	ok2: close({a: 1})
}

maxFields: {
	[string]: struct.MaxFields(1)

	ok1: {}
	ok2: {a: 1}
	ok3: close({a: 1})

	fail1: {a: 1, b: 2}
}

-- out/structs --
Errors:
minFields.fail1: invalid value {} (does not satisfy struct.MinFields(1)): len(fields) < MinFields(1) (0 < 1):
    ./in.cue:4:12
    ./in.cue:4:29
    ./in.cue:7:9
maxFields.fail1: invalid value {a:1,b:2} (does not satisfy struct.MaxFields(1)): len(fields) > MaxFields(1) (2 > 1):
    ./in.cue:13:12
    ./in.cue:13:29
    ./in.cue:19:9

Result:
import "struct"

minFields: {
	incomplete1: {} & struct.MinFields(1)
	fail1: _|_ // minFields.fail1: invalid value {} (does not satisfy struct.MinFields(1)): len(fields) < MinFields(1) (0 < 1)
	ok1: {
		a: 1
	}
	ok2: {
		a: 1
	}
}
maxFields: {
	ok1: {}
	ok2: {
		a: 1
	}
	ok3: {
		a: 1
	}
	fail1: _|_ // maxFields.fail1: invalid value {a:1,b:2} (does not satisfy struct.MaxFields(1)): len(fields) > MaxFields(1) (2 > 1)
}