From 54b8ec50a45ae4b475f6432f5ba23d7c0101d6ca Mon Sep 17 00:00:00 2001
From: reginaldalfret <reginaldalfret@gmail.com>
Date: Mon, 19 Oct 2026 23:32:07 +0530
Subject: [PATCH] Fix implicit null converted to empty string in flow mappings

---
 formatters/basic/formatter_test.go | 14 +++++++-------
 pkg/yaml/emitterc.go               |  4 ++--
 pkg/yaml/node_test.go              | 11 +++++++++++
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/formatters/basic/formatter_test.go b/formatters/basic/formatter_test.go
index 9ec0c880..c9b9641d 100644
--- a/formatters/basic/formatter_test.go
+++ b/formatters/basic/formatter_test.go
@@ -235,6 +235,11 @@ map:
 map:
   *a : 1`,
 		},
+		{
+			name:   "retains implicit null in flow mapping",
+			input:  `a: {b: }`,
+			expect: `a: {b:}`,
+		},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
@@ -397,12 +402,7 @@ func TestRetainLineBreaksLongLine(t *testing.T) {
 
 func stripTrailingNewline(s string) string {
 	// strip trailing \n or \r\n characters
-	if len(s) > 0 {
-		if s[len(s)-1] == '\n' {
-			s = s[:len(s)-1]
-		} else if len(s) > 1 && s[len(s)-2] == '\r' {
-			s = s[:len(s)-2]
-		}
-	}
+	s = strings.TrimSuffix(s, "\r\n")
+	s = strings.TrimSuffix(s, "\n")
 	return s
 }
diff --git a/pkg/yaml/emitterc.go b/pkg/yaml/emitterc.go
index 3a1aede9..e0b3201c 100644
--- a/pkg/yaml/emitterc.go
+++ b/pkg/yaml/emitterc.go
@@ -1056,7 +1056,7 @@ func yaml_emitter_select_scalar_style(emitter *yaml_emitter_t, event *yaml_event
 			emitter.flow_level == 0 && !emitter.scalar_data.block_plain_allowed {
 			style = yaml_SINGLE_QUOTED_SCALAR_STYLE
 		}
-		if len(emitter.scalar_data.value) == 0 && (emitter.flow_level > 0 || emitter.simple_key_context) {
+		if len(emitter.scalar_data.value) == 0 && emitter.simple_key_context {
 			style = yaml_SINGLE_QUOTED_SCALAR_STYLE
 		}
 		if no_tag && !event.implicit {
@@ -1312,7 +1312,7 @@ func yaml_emitter_analyze_scalar(emitter *yaml_emitter_t, value []byte) bool {
 
 	if len(value) == 0 {
 		emitter.scalar_data.multiline = false
-		emitter.scalar_data.flow_plain_allowed = false
+		emitter.scalar_data.flow_plain_allowed = true
 		emitter.scalar_data.block_plain_allowed = true
 		emitter.scalar_data.single_quoted_allowed = true
 		emitter.scalar_data.block_allowed = false
diff --git a/pkg/yaml/node_test.go b/pkg/yaml/node_test.go
index 24a1dcc6..5d722130 100644
--- a/pkg/yaml/node_test.go
+++ b/pkg/yaml/node_test.go
@@ -2856,6 +2856,17 @@ func (s *S) TestNodeOmitEmpty(c *C) {
 	c.Assert(err, ErrorMatches, "yaml: cannot encode node with unknown kind 0")
 }
 
+func (s *S) TestFlowMappingImplicitNull(c *C) {
+	input := "a: {b: }\n"
+	var n yaml.Node
+	err := yaml.Unmarshal([]byte(input), &n)
+	c.Assert(err, IsNil)
+
+	data, err := yaml.Marshal(&n)
+	c.Assert(err, IsNil)
+	c.Assert(string(data), Equals, "a: {b:}\n")
+}
+
 func fprintComments(out io.Writer, node *yaml.Node, indent string) {
 	switch node.Kind {
 	case yaml.ScalarNode: