Update: show the original identifier place (refs eslint#13646)

lib/rules/no-shadow.js

@@ -44,7 +44,7 @@ module.exports = {
         ],
 
         messages: {
-            noShadow: "'{{name}}' is already declared in the upper scope."
+            noShadow: "'{{name}}' is already declared in the upper scope {{shadowedLine}}:{{shadowedColumn}}."
         }
     },
 
@@ -117,6 +117,29 @@ module.exports = {
             return def && def.name.range;
         }
 
+        /**
+         * Get declared line and column of a variable.
+         * @param {eslint-scope.Variable} variable The variable to get.
+         * @returns {Object|undefined} The declared line and column of the variable.
+         */
+        function getDeclaredLocation(variable) {
+            const identifier = variable.identifiers[0];
+            let obj;
+
+            if (identifier) {
+                obj = {
+                    line: identifier.loc.start.line,
+                    column: identifier.loc.start.column + 1
+                };
+            } else {
+                obj = {
+                    line: 0,
+                    column: 0
+                };
+            }
+            return obj;
+        }
+
         /**
          * Checks if a variable is in TDZ of scopeVar.
          * @param {Object} variable The variable to check.
@@ -165,6 +188,10 @@ module.exports = {
                     !isOnInitializer(variable, shadowed) &&
                     !(options.hoist !== "all" && isInTdz(variable, shadowed))
                 ) {
+                    const location = getDeclaredLocation(shadowed);
+
+                    variable.shadowedLine = location.line;
+                    variable.shadowedColumn = location.column;
                     context.report({
                         node: variable.identifiers[0],
                         messageId: "noShadow",