Merge anchor traversing: add test for aliased sequence, cleanup

pkg/yqlib/operator_traverse_path.go

@@ -293,9 +293,10 @@ func doTraverseMap(newMatches *orderedmap.OrderedMap, node *CandidateNode, wante
 }
 
 func traverseMergeAnchor(newMatches *orderedmap.OrderedMap, value *CandidateNode, wantedKey string, prefs traversePreferences, splat bool) error {
+	if value.Kind == AliasNode {
+		value = value.Alias
+	}
 	switch value.Kind {
-	case AliasNode:
-		return traverseMergeAnchor(newMatches, value.Alias, wantedKey, prefs, splat)
 	case MappingNode:
 		return doTraverseMap(newMatches, value, wantedKey, prefs, splat)
 	case SequenceNode:
@@ -313,10 +314,10 @@ func traverseMergeAnchor(newMatches *orderedmap.OrderedMap, value *CandidateNode
 				return err
 			}
 		}
+		return nil
 	default:
 		return fmt.Errorf("can only use merge anchors with maps (!!map) or sequences (!!seq) of maps, but got %v", value.Tag)
 	}
-	return nil
 }
 
 func traverseArray(candidate *CandidateNode, operation *Operation, prefs traversePreferences) (*list.List, error) {

pkg/yqlib/operator_traverse_path_test.go

@@ -365,7 +365,7 @@ var traversePathOperatorScenarios = []expressionScenario{
 			"D0, P[0], (!!null)::null\n",
 		},
 	},
-	{
+	{ // Merge anchor with inline map
 		skipDoc:    true,
 		document:   `{<<: {a: 42}}`,
 		expression: `.a`,
@@ -373,7 +373,7 @@ var traversePathOperatorScenarios = []expressionScenario{
 			"D0, P[<< a], (!!int)::42\n",
 		},
 	},
-	{
+	{ // Merge anchor with sequence with inline map
 		skipDoc:    true,
 		document:   `{<<: [{a: 42}]}`,
 		expression: `.a`,
@@ -381,6 +381,14 @@ var traversePathOperatorScenarios = []expressionScenario{
 			"D0, P[<< 0 a], (!!int)::42\n",
 		},
 	},
+	{ // Merge anchor with aliased sequence with inline map
+		skipDoc:    true,
+		document:   `{s: &s [{a: 42}], m: {<<: *s}}`,
+		expression: `.m.a`,
+		expected: []string{
+			"D0, P[s 0 a], (!!int)::42\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		document:   mergeDocSample,