From f08a129a85e29c5a66005d7d00bcf2d71ca89863 Mon Sep 17 00:00:00 2001
From: Satyaki Ghosh <satyakig@amazon.com>
Date: Mon, 6 Jul 2026 14:24:08 -0400
Subject: [PATCH] Fix yaml line numbers

---
 src/template-model/src/parser/yaml.rs | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/src/template-model/src/parser/yaml.rs b/src/template-model/src/parser/yaml.rs
index 2ef6df1..c04cbac 100644
--- a/src/template-model/src/parser/yaml.rs
+++ b/src/template-model/src/parser/yaml.rs
@@ -257,12 +257,14 @@ impl MarkedEventReceiver for CfnYamlLoader {
                             }
                             self.path_stack.push(v.clone());
                             let path = self.current_path();
-                            // mark.line() and mark.col() are 0-based
-                            self.span_map.insert(path, (mark.line() as u32 + 1, mark.col() as u32 + 1));
+                            // yaml_rust2 Marker reports line 1-based but column 0-based,
+                            // so only the column is shifted to the 1-based column every
+                            // other diagnostic reports (see the parse-error path above).
+                            self.span_map.insert(path, (mark.line() as u32, mark.col() as u32 + 1));
                             // Remember this key's position so a later duplicate of it
                             // can be anchored at the offending occurrence.
                             if let Some(slot) = self.key_marks.last_mut() {
-                                *slot = Some((mark.line() as u32 + 1, mark.col() as u32 + 1));
+                                *slot = Some((mark.line() as u32, mark.col() as u32 + 1));
                             }
                         }
                     } else if matches!(parent.0, Yaml::Array(_))
@@ -549,10 +551,6 @@ mod tests {
         assert_eq!(messages(&yaml), messages(&json));
     }
 
-    /// A bare (integer) YAML key and a quoted string key of the same digits are
-    /// distinct source keys, so — matching cfn-lint, which compares keys by value
-    /// and never flags them — no F0000 is emitted. (The two are coerced to the same
-    /// string later, but that must not manufacture a duplicate diagnostic.)
     #[test]
     fn integer_key_and_string_key_are_not_duplicates() {
         let input = "Resources:\n  R:\n    Type: AWS::S3::Bucket\n    Metadata:\n      1: a\n      \"1\": b\n";
@@ -1023,9 +1021,6 @@ mod tests {
         );
     }
 
-    /// A literal duplicate key inside a mapping that also uses `<<` is suppressed,
-    /// matching cfn-lint's `using_merge` behavior (the whole mapping's dup check is
-    /// disabled). Ordering of the duplicate relative to `<<` must not matter.
     #[test]
     fn yaml_merge_key_suppresses_literal_duplicate_in_same_mapping() {
         let input = "Anchors:\n  Base: &base\n    X: 1\nResources:\n  Derived:\n    Type: AWS::S3::Bucket\n    Dup: 1\n    Dup: 2\n    <<: *base\n";