From 665f6b02674afc921b1f46c7fc61a0d02fecc704 Mon Sep 17 00:00:00 2001
From: Mike Farah <mikefarah@gmail.com>
Date: Sun, 20 Feb 2022 14:29:52 +1100
Subject: [PATCH] Fixed self assigned issue #1107

---
 pkg/yqlib/candidate_node.go           | 17 +++++++++++-----
 pkg/yqlib/lib.go                      | 28 +++++++++++++++++++++++++++
 pkg/yqlib/operator_anchors_aliases.go |  2 +-
 pkg/yqlib/operator_assign_test.go     |  9 +++++++++
 release_notes.txt                     |  3 +++
 5 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/pkg/yqlib/candidate_node.go b/pkg/yqlib/candidate_node.go
index c8fe1402..18dc60e9 100644
--- a/pkg/yqlib/candidate_node.go
+++ b/pkg/yqlib/candidate_node.go
@@ -116,15 +116,24 @@ func (n *CandidateNode) Copy() (*CandidateNode, error) {
 	if err != nil {
 		return nil, err
 	}
+	clone.Node = deepClone(n.Node)
 	return clone, nil
 }
 
 // updates this candidate from the given candidate node
 func (n *CandidateNode) UpdateFrom(other *CandidateNode, prefs assignPreferences) {
 
-	n.UpdateAttributesFrom(other, prefs)
-	n.Node.Content = other.Node.Content
+	// if this is an empty map or empty array, use the style of other node.
+	if n.Node.Kind != yaml.ScalarNode && len(n.Node.Content) == 0 {
+		n.Node.Style = other.Node.Style
+	}
+
+	n.Node.Content = deepCloneContent(other.Node.Content)
+	n.Node.Kind = other.Node.Kind
 	n.Node.Value = other.Node.Value
+
+	n.UpdateAttributesFrom(other, prefs)
+
 }
 
 func (n *CandidateNode) UpdateAttributesFrom(other *CandidateNode, prefs assignPreferences) {
@@ -150,10 +159,8 @@ func (n *CandidateNode) UpdateAttributesFrom(other *CandidateNode, prefs assignP
 
 	// merge will pickup the style of the new thing
 	// when autocreating nodes
-	//
-	// if this is an empty map or empty array, use the style of other node.
 
-	if n.Node.Style == 0 || (n.Node.Kind != yaml.ScalarNode && len(n.Node.Content) == 0) {
+	if n.Node.Style == 0 {
 		n.Node.Style = other.Node.Style
 	}
 
diff --git a/pkg/yqlib/lib.go b/pkg/yqlib/lib.go
index db91dcca..3175ed30 100644
--- a/pkg/yqlib/lib.go
+++ b/pkg/yqlib/lib.go
@@ -245,7 +245,35 @@ func recursiveNodeEqual(lhs *yaml.Node, rhs *yaml.Node) bool {
 		return recurseNodeObjectEqual(lhs, rhs)
 	}
 	return false
+}
 
+func deepCloneContent(content []*yaml.Node) []*yaml.Node {
+	clonedContent := make([]*yaml.Node, len(content))
+	for i, child := range content {
+		clonedContent[i] = deepClone(child)
+	}
+	return clonedContent
+}
+
+func deepClone(node *yaml.Node) *yaml.Node {
+	if node == nil {
+		return nil
+	}
+	clonedContent := deepCloneContent(node.Content)
+	return &yaml.Node{
+		Content:     clonedContent,
+		Kind:        node.Kind,
+		Style:       node.Style,
+		Tag:         node.Tag,
+		Value:       node.Value,
+		Anchor:      node.Anchor,
+		Alias:       deepClone(node.Alias),
+		HeadComment: node.HeadComment,
+		LineComment: node.LineComment,
+		FootComment: node.FootComment,
+		Line:        node.Line,
+		Column:      node.Column,
+	}
 }
 
 // yaml numbers can be hex encoded...
diff --git a/pkg/yqlib/operator_anchors_aliases.go b/pkg/yqlib/operator_anchors_aliases.go
index 9d512bcd..d5cbb3f0 100644
--- a/pkg/yqlib/operator_anchors_aliases.go
+++ b/pkg/yqlib/operator_anchors_aliases.go
@@ -201,7 +201,7 @@ func explodeNode(node *yaml.Node, context Context) error {
 			node.Kind = node.Alias.Kind
 			node.Style = node.Alias.Style
 			node.Tag = node.Alias.Tag
-			node.Content = node.Alias.Content
+			node.Content = deepCloneContent(node.Alias.Content)
 			node.Value = node.Alias.Value
 			node.Alias = nil
 		}
diff --git a/pkg/yqlib/operator_assign_test.go b/pkg/yqlib/operator_assign_test.go
index b5f6813c..42d11b24 100644
--- a/pkg/yqlib/operator_assign_test.go
+++ b/pkg/yqlib/operator_assign_test.go
@@ -28,6 +28,15 @@ var assignOperatorScenarios = []expressionScenario{
 			"D0, P[], (doc)::{a: null}\n",
 		},
 	},
+	{
+		skipDoc:     true,
+		description: "self reference",
+		document:    "a: cat",
+		expression:  `.a = [.a]`,
+		expected: []string{
+			"D0, P[], (doc)::a:\n    - cat\n",
+		},
+	},
 	{
 		description: "Update node to be the child value",
 		document:    `{a: {b: {g: foof}}}`,
diff --git a/release_notes.txt b/release_notes.txt
index 7a849935..ea8a017c 100644
--- a/release_notes.txt
+++ b/release_notes.txt
@@ -1,3 +1,6 @@
+4.20.2:
+  - Fixed self assignment issue (#1107)
+
 4.20.1:
   - New [Date Operators]((https://mikefarah.gitbook.io/yq/operators/datetime)) (now, tz, add and subtract durations from dates) 
   - Can now decode property files!