Remove redundant check and add test case for explicit !!merge on *+ traversal

pkg/yqlib/operator_anchors_aliases_test.go

@@ -319,6 +319,18 @@ somethingElse:
 `
 
 var anchorOperatorScenarios = []expressionScenario{
+	{
+		// mergeObjects previously skipped all !!merge-tagged nodes. Since !!merge only appears on
+		// << map keys, this meant applyAssignment was never called for the << key. It was later
+		// autocreated by createStringScalarNode("<<") with tag !!str, silently dropping !!merge.
+		// DontFollowAlias:true already prevents aliases being followed, so the skip was redundant.
+		// Old (buggy) output: "D0, P[], (!!map)::base: &base\n    x: 1\ndest:\n    <<: *base\n"
+		skipDoc:     true,
+		description: "direct *+ preserves explicit !!merge tag on << key (regression for issue 2677)",
+		document:    "base: &base\n    x: 1\ndest:\n    !!merge <<: *base\n",
+		expression:  `. as $d | {} *+ $d`,
+		expected:    []string{"D0, P[], (!!map)::base: &base\n    x: 1\ndest:\n    !!merge <<: *base\n"},
+	},
 	{
 		skipDoc:     true,
 		description: "explicit !!merge tag on << key is preserved through ireduce merge",

pkg/yqlib/operator_multiply.go

@@ -189,10 +189,6 @@ func mergeObjects(d *dataTreeNavigator, context Context, lhs *CandidateNode, rhs
 
 		log.Debugf("going to applied assignment to LHS: %v with RHS: %v", NodeToString(lhs), NodeToString(candidate))
 
-		if candidate.Tag == "!!merge" && !candidate.IsMapKey {
-			continue
-		}
-
 		err := applyAssignment(d, context, pathIndexToStartFrom, lhs, candidate, preferences)
 		if err != nil {
 			return nil, err