diff --git a/packages/localize/src/utils/src/messages.ts b/packages/localize/src/utils/src/messages.ts
index fdf938276a..e19593ccdf 100644
--- a/packages/localize/src/utils/src/messages.ts
+++ b/packages/localize/src/utils/src/messages.ts
@@ -48,6 +48,7 @@ export interface SourceLocation {
   start: {line: number, column: number};
   end: {line: number, column: number};
   file: AbsoluteFsPath;
+  text?: string;
 }
 
 /**
@@ -118,10 +119,18 @@ export interface ParsedMessage extends MessageMetadata {
    * A mapping of placeholder names to substitution values.
    */
   substitutions: Record<string, any>;
+  /**
+   * An optional mapping of placeholder names to source locations
+   */
+  substitutionLocations?: Record<string, SourceLocation|undefined>;
   /**
    * The static parts of the message.
    */
   messageParts: string[];
+  /**
+   * An optional mapping of message parts to source locations
+   */
+  messagePartLocations?: (SourceLocation|undefined)[];
   /**
    * The names of the placeholders that will be replaced with substitutions.
    */
@@ -135,9 +144,11 @@ export interface ParsedMessage extends MessageMetadata {
  * See `ParsedMessage` for an example.
  */
 export function parseMessage(
-    messageParts: TemplateStringsArray, expressions?: readonly any[],
-    location?: SourceLocation): ParsedMessage {
+    messageParts: TemplateStringsArray, expressions?: readonly any[], location?: SourceLocation,
+    messagePartLocations?: (SourceLocation|undefined)[],
+    expressionLocations: (SourceLocation|undefined)[] = []): ParsedMessage {
   const substitutions: {[placeholderName: string]: any} = {};
+  const substitutionLocations: {[placeholderName: string]: SourceLocation|undefined} = {};
   const metadata = parseMetadata(messageParts[0], messageParts.raw[0]);
   const cleanedMessageParts: string[] = [metadata.text];
   const placeholderNames: string[] = [];
@@ -148,6 +159,7 @@ export function parseMessage(
     messageString += `{$${placeholderName}}${messagePart}`;
     if (expressions !== undefined) {
       substitutions[placeholderName] = expressions[i - 1];
+      substitutionLocations[placeholderName] = expressionLocations[i - 1];
     }
     placeholderNames.push(placeholderName);
     cleanedMessageParts.push(messagePart);
@@ -158,11 +170,13 @@ export function parseMessage(
     id: messageId,
     legacyIds,
     substitutions,
+    substitutionLocations,
     text: messageString,
     customId: metadata.customId,
     meaning: metadata.meaning || '',
     description: metadata.description || '',
     messageParts: cleanedMessageParts,
+    messagePartLocations,
     placeholderNames,
     location,
   };