pkg/list: MatchN matches in final mode

Matching is defined on final values. Make this
analogous to matchN.

Also change the second Validate to Err.

Fixes #3519

Signed-off-by: Marcel van Lohuizen <mpvl@gmail.com>
Change-Id: I7fe2f6f977e3c589db2aa0103256a4f64ab1ceb2
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1204425
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Roger Peppe <rogpeppe@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>

Author: mpvl

pkg/list/list.go

@@ -333,15 +333,15 @@ func Contains(a []cue.Value, v cue.Value) bool {
 func MatchN(list []cue.Value, n pkg.Schema, matchValue pkg.Schema) (bool, error) {
 	var nmatch int64
 	for _, w := range list {
-		if matchValue.Unify(w).Validate() == nil {
+		if matchValue.Unify(w).Validate(cue.Final()) == nil {
 			nmatch++
 		}
 	}
 
 	r, _ := value.ToInternal(n)
 	ctx := (*cue.Context)(r)
 
-	if err := n.Unify(ctx.Encode(nmatch)).Validate(); err != nil {
+	if err := n.Unify(ctx.Encode(nmatch)).Err(); err != nil {
 		return false, pkg.ValidationError{B: &adt.Bottom{
 			Code: adt.EvalError,
 			Err: errors.Newf(

pkg/list/testdata/matchn_err.txtar

@@ -47,6 +47,10 @@ t1.l6: invalid value [1,2,3,"str",[1],{foo:1}] (does not satisfy list.MatchN): n
     ./in.cue:11:6
     ./in.cue:4:12
     ./in.cue:11:18
+issue3519.a: invalid value [{}] (does not satisfy list.MatchN): number of matched elements is 0: does not satisfy 1:
+    ./in.cue:16:8
+    ./in.cue:15:8
+    ./in.cue:16:20
 
 Result:
 t1: {
@@ -58,7 +62,7 @@ t1: {
 	l6: _|_ // t1.l6: invalid value [1,2,3,"str",[1],{foo:1}] (does not satisfy list.MatchN): number of matched elements is 0: does not satisfy >0
 }
 issue3519: {
-	a: [{}]
+	a: _|_ // issue3519.a: invalid value [{}] (does not satisfy list.MatchN): number of matched elements is 0: does not satisfy 1
 }
 #TOO: {
 	too: int