nodeca · puzrin · Feb 3, 2017 · Feb 3, 2017
diff --git a/lib/js-yaml/loader.js b/lib/js-yaml/loader.js
@@ -281,7 +281,7 @@ function mergeMappings(state, destination, source, overridableKeys) {
   }
 }
 
-function storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valueNode) {
+function storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valueNode, startLine, startPos) {
   var index, quantity;
 
   keyNode = String(keyNode);
@@ -302,6 +302,8 @@ function storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valu
     if (!state.json &&
         !_hasOwnProperty.call(overridableKeys, keyNode) &&
         _hasOwnProperty.call(_result, keyNode)) {
+      state.line = startLine || state.line;
+      state.position = startPos || state.position;
       throwError(state, 'duplicated mapping key');
     }
     _result[keyNode] = valueNode;
@@ -949,6 +951,7 @@ function readBlockMapping(state, nodeIndent, flowIndent) {
   var following,
       allowCompact,
       _line,
+      _pos,
       _tag          = state.tag,
       _anchor       = state.anchor,
       _result       = {},
@@ -969,6 +972,7 @@ function readBlockMapping(state, nodeIndent, flowIndent) {
   while (ch !== 0) {
     following = state.input.charCodeAt(state.position + 1);
     _line = state.line; // Save the current line.
+    _pos = state.position;
 
     //
     // Explicit notation case. There are two separate blocks:
@@ -1063,7 +1067,7 @@ function readBlockMapping(state, nodeIndent, flowIndent) {
       }
 
       if (!atExplicitKey) {
-        storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valueNode);
+        storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valueNode, _line, _pos);
         keyTag = keyNode = valueNode = null;
       }
 

diff --git a/test/issues/0243-basic.yml b/test/issues/0243-basic.yml
@@ -0,0 +1,15 @@
+a:
+  b: 1
+  c: 2
+d:
+  e: 3
+  f: 4
+duplicate: # 1
+  id: 1234
+  note: "this is the first one, so it won't raise an error"
+duplicate: # 2
+  id: 5678
+  note: "this is the second one, so it will raise an error, hopefully at the start of the key"
+g:
+  h: 5
+  i: 6
diff --git a/test/issues/0243-nested.yml b/test/issues/0243-nested.yml
@@ -0,0 +1,15 @@
+a:
+  b: 1
+  c: 2
+d:
+  e: 3
+  f: 4
+  duplicate: # 1
+    id: 1234
+    note: "this is the first one, so it won't raise an error"
+  duplicate: # 2
+    id: 5678
+    note: "this is the second one, so it will raise an error, hopefully at the start of the key"
+g:
+  h: 5
+  i: 6
diff --git a/test/issues/0243.js b/test/issues/0243.js
@@ -0,0 +1,29 @@
+'use strict';
+
+
+var assert = require('assert');
+var yaml   = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Duplicated mapping key errors on top level throw at beginning of key', function () {
+  var src = readFileSync(require('path').join(__dirname, '/0243-basic.yml'), 'utf8');
+  var lines = src.split('\n');
+
+  try {
+    yaml.safeLoad(src);
+  } catch (e) {
+    assert.equal(lines[e.mark.line], 'duplicate: # 2');
+  }
+});
+
+test('Duplicated mapping key errors inside of mapping values throw at beginning of key', function () {
+  var src = readFileSync(require('path').join(__dirname, '/0243-nested.yml'), 'utf8');
+  var lines = src.split('\n');
+
+  try {
+    yaml.safeLoad(src);
+  } catch (e) {
+    assert.equal(lines[e.mark.line], '  duplicate: # 2');
+  }
+});