2 files changed, 102 insertions, 12 deletions

diff --git a/src/WixToolset.Converters/WixConverter.cs b/src/WixToolset.Converters/WixConverter.cs
index b8f2a516..1ef57fe7 100644
--- a/src/WixToolset.Converters/WixConverter.cs
+++ b/src/WixToolset.Converters/WixConverter.cs
@@ -179,6 +179,8 @@ namespace WixToolset.Converters
         };
 
         private readonly Dictionary<XName, Action<XElement>> ConvertElementMapping;
+        private readonly Regex DeprecatedPrefixRegex = new Regex(@"(?<=(^|[^\$])(\$\$)*)\$(?=\(loc\.[^.].*\))",
+            RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.ExplicitCapture);
 
         /// <summary>
         /// Instantiate a new Converter class.
@@ -427,6 +429,13 @@ namespace WixToolset.Converters
             {
                 if (node is XText text)
                 {
+                    if (null != text.Value)
+                    {
+                        if (this.TryFixDeprecatedLocalizationPrefixes(node, text.Value, out var newValue, ConverterTestType.DeprecatedLocalizationVariablePrefixInTextValue))
+                        {
+                            text.Value = newValue;
+                        }
+                    }
                     if (!String.IsNullOrWhiteSpace(text.Value))
                     {
                         text.Value = text.Value.Trim();
@@ -464,6 +473,20 @@ namespace WixToolset.Converters
             }
         }
 
+        private bool TryFixDeprecatedLocalizationPrefixes(XNode node, string value, out string newValue, ConverterTestType testType)
+        {
+            newValue = this.DeprecatedPrefixRegex.Replace(value, "!");
+
+            if (object.ReferenceEquals(newValue, value))
+            {
+                return false;
+            }
+
+            var message = testType == ConverterTestType.DeprecatedLocalizationVariablePrefixInTextValue ? "The prefix on the localization variable in the inner text is incorrect." : "The prefix on the localization variable in the attribute value is incorrect.";
+
+            return this.OnError(testType, node, message);
+        }
+
         private void EnsurePrecedingWhitespaceCorrect(XText whitespace, XNode node, int level, ConverterTestType testType)
         {
             if (!WixConverter.LeadingWhitespaceValid(this.IndentationAmount, level, whitespace.Value))
@@ -492,25 +515,40 @@ namespace WixToolset.Converters
 
         private void ConvertElement(XElement element)
         {
-            // Gather any deprecated namespaces, then update this element tree based on those deprecations.
             var deprecatedToUpdatedNamespaces = new Dictionary<XNamespace, XNamespace>();
 
-            foreach (var declaration in element.Attributes().Where(a => a.IsNamespaceDeclaration))
+            foreach (var attribute in element.Attributes())
             {
-                if (element.Name == Wix3ElementName || element.Name == Include3ElementName)
-                {
-                    this.SourceVersion = 3;
-                }
-                else if (element.Name == Wix4ElementName || element.Name == Include4ElementName)
+                if (attribute.IsNamespaceDeclaration)
                 {
-                    this.SourceVersion = 4;
-                }
+                    // Gather any deprecated namespaces, then update this element tree based on those deprecations.
+                    var declaration = attribute;
 
-                if (WixConverter.OldToNewNamespaceMapping.TryGetValue(declaration.Value, out var ns))
+                    if (element.Name == Wix3ElementName || element.Name == Include3ElementName)
+                    {
+                        this.SourceVersion = 3;
+                    }
+                    else if (element.Name == Wix4ElementName || element.Name == Include4ElementName)
+                    {
+                        this.SourceVersion = 4;
+                    }
+
+                    if (WixConverter.OldToNewNamespaceMapping.TryGetValue(declaration.Value, out var ns))
+                    {
+                        if (this.OnError(ConverterTestType.XmlnsValueWrong, declaration, "The namespace '{0}' is out of date.  It must be '{1}'.", declaration.Value, ns.NamespaceName))
+                        {
+                            deprecatedToUpdatedNamespaces.Add(declaration.Value, ns);
+                        }
+                    }
+                }
+                else
                 {
-                    if (this.OnError(ConverterTestType.XmlnsValueWrong, declaration, "The namespace '{0}' is out of date.  It must be '{1}'.", declaration.Value, ns.NamespaceName))
+                    if (null != attribute.Value)
                     {
-                        deprecatedToUpdatedNamespaces.Add(declaration.Value, ns);
+                        if (this.TryFixDeprecatedLocalizationPrefixes(element, attribute.Value, out var newValue, ConverterTestType.DeprecatedLocalizationVariablePrefixInAttributeValue))
+                        {
+                            attribute.Value = newValue;
+                        }
                     }
                 }
             }
@@ -1958,11 +1996,15 @@ namespace WixToolset.Converters
             /// </summary>
             WhitespacePrecedingEndElementWrong,
 
+            // Before this point, ignore errors on convert operation
+
             /// <summary>
             /// Displayed when the XML declaration is present in the source file.
             /// </summary>
             DeclarationPresent,
 
+            // After this point, ignore errors on format operation
+
             /// <summary>
             /// Displayed when the xmlns attribute is missing from the document element.
             /// </summary>
@@ -1974,6 +2016,16 @@ namespace WixToolset.Converters
             XmlnsValueWrong,
 
             /// <summary>
+            /// Displayed when inner text contains a deprecated $(loc.xxx) reference.
+            /// </summary>
+            DeprecatedLocalizationVariablePrefixInTextValue,
+
+            /// <summary>
+            /// Displayed when an attribute value contains a deprecated $(loc.xxx) reference.
+            /// </summary>
+            DeprecatedLocalizationVariablePrefixInAttributeValue,
+
+            /// <summary>
             /// Assign an identifier to a File element when on Id attribute is specified.
             /// </summary>
             AssignAnonymousFileId,
diff --git a/src/test/WixToolsetTest.Converters/ConverterFixture.cs b/src/test/WixToolsetTest.Converters/ConverterFixture.cs
index 39521da0..13df9da7 100644
--- a/src/test/WixToolsetTest.Converters/ConverterFixture.cs
+++ b/src/test/WixToolsetTest.Converters/ConverterFixture.cs
@@ -407,5 +407,43 @@ namespace WixToolsetTest.Converters
             Assert.Equal(2, errors);
             Assert.Equal(expected, actual);
         }
+
+        [Fact]
+        public void CanConvertDeprecatedPrefix()
+        {
+            var parse = String.Join(Environment.NewLine,
+                "<Wix xmlns=\"http://wixtoolset.org/schemas/v4/wxs\">",
+                "<Fragment>",
+                "<ComponentGroup Id=\"$(loc.Variable)\" />",
+                "<ComponentGroup Id=\"$$(loc.Variable)\" />",
+                "<ComponentGroup Id=\"$$$(loc.Variable)\" />",
+                "<ComponentGroup Id=\"$$$$(loc.Variable)\" />",
+                "<ComponentGroup Id=\"$$$$$(loc.Variable)\" />",
+                "</Fragment>",
+                "</Wix>");
+
+            var expected = String.Join(Environment.NewLine,
+                "<Wix xmlns=\"http://wixtoolset.org/schemas/v4/wxs\">",
+                "<Fragment>",
+                "<ComponentGroup Id=\"!(loc.Variable)\" />",
+                "<ComponentGroup Id=\"$$(loc.Variable)\" />",
+                "<ComponentGroup Id=\"$$!(loc.Variable)\" />",
+                "<ComponentGroup Id=\"$$$$(loc.Variable)\" />",
+                "<ComponentGroup Id=\"$$$$!(loc.Variable)\" />",
+                "</Fragment>",
+                "</Wix>");
+
+            var document = XDocument.Parse(parse, LoadOptions.PreserveWhitespace | LoadOptions.SetLineInfo);
+
+            var messaging = new MockMessaging();
+            var converter = new WixConverter(messaging, 2, null, null);
+
+            var errors = converter.ConvertDocument(document);
+
+            var actual = UnformattedDocumentString(document);
+
+            Assert.Equal(3, errors);
+            Assert.Equal(expected, actual);
+        }
     }
 }