internal/core/adt: fix disjunctions in data mode

The toDataAll path is currently not used, but will
be used in the upcoming matchN builtin.

In data mode, defaults of disjunctons should be taken
and a non-ambiguous default should consequently be
converted to data also.

This will be tested as part of the matchN builtin.

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: I40c1fed6c6c2284c750c3f9115a8ea6456bcc37a
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1199550
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>

internal/core/adt/composite.go

@@ -760,8 +760,18 @@ func toDataAll(ctx *OpContext, v BaseValue) BaseValue {
 	// to avoid issues with the closedness algorithm down the line.
 	case *Disjunction:
 		d := *x
-		d.Values = make([]Value, len(x.Values))
-		for i, v := range x.Values {
+		values := x.Values
+		// Data mode involves taking default values and if there is an
+		// unambiguous default value, we should convert that to data as well.
+		switch x.NumDefaults {
+		case 0:
+		case 1:
+			return toDataAll(ctx, values[0])
+		default:
+			values = values[:x.NumDefaults]
+		}
+		d.Values = make([]Value, len(values))
+		for i, v := range values {
 			switch x := v.(type) {
 			case *Vertex:
 				d.Values[i] = x.ToDataAll(ctx)