[eslint-plugin] Fix no-external-local-imports in editor (#5441)

* [eslint-plugin] Fix calculation of project folder in ESLint
* [heft-lint] Set parserOptions.tsconfigRootDir

---------

Co-authored-by: David Michon <dmichon-msft@users.noreply.github.com>

Author: dmichon-msft

common/changes/@rushstack/eslint-plugin/fix-lint-dir_2025-11-11-01-37.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/eslint-plugin",
+      "comment": "Fix calculation of project root folder when using the ESLint extension in VS Code. Report the paths being compared in 'no-external-local-imports' rule violations.",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@rushstack/eslint-plugin"
+}

common/changes/@rushstack/heft-lint-plugin/fix-lint-dir_2025-11-11-02-24.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/heft-lint-plugin",
+      "comment": "Ensure that `parserOptions.tsconfigRootDir` is set for use by custom lint rules.",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@rushstack/heft-lint-plugin"
+}

eslint/eslint-plugin/src/LintUtilities.ts

@@ -4,7 +4,7 @@
 import * as path from 'node:path';
 
 import { ESLintUtils, TSESTree, type TSESLint } from '@typescript-eslint/utils';
-import type { Program } from 'typescript';
+import type { CompilerOptions, Program } from 'typescript';
 
 export interface IParsedImportSpecifier {
   loader?: string;
@@ -33,23 +33,41 @@ export function getFilePathFromContext(context: TSESLint.RuleContext<string, unk
 export function getRootDirectoryFromContext(
   context: TSESLint.RuleContext<string, unknown[]>
 ): string | undefined {
-  let rootDirectory: string | undefined;
+  /*
+   * Precedence of root directory resolution:
+   * 1. parserOptions.tsconfigRootDir if available (since set by repo maintainer)
+   * 2. tsconfig.json directory if available (but might be in a subfolder)
+   * 3. TS Program current directory if available
+   * 4. ESLint working directory (probably wrong, but better than nothing?)
+   */
+  const tsConfigRootDir: string | undefined = context.parserOptions?.tsconfigRootDir;
+  if (tsConfigRootDir) {
+    return tsConfigRootDir;
+  }
+
   try {
-    // First attempt to get the root directory from the tsconfig baseUrl, then the program current directory
     const program: Program | null | undefined = (
       context.sourceCode?.parserServices ?? ESLintUtils.getParserServices(context)
     ).program;
-    rootDirectory = program?.getCompilerOptions().baseUrl ?? program?.getCurrentDirectory();
+    const compilerOptions: CompilerOptions | undefined = program?.getCompilerOptions();
+
+    const tsConfigPath: string | undefined = compilerOptions?.configFilePath as string | undefined;
+    if (tsConfigPath) {
+      const tsConfigDir: string = path.dirname(tsConfigPath);
+      return tsConfigDir;
+    }
+
+    // Next, try to get the current directory from the TS program
+    const rootDirectory: string | undefined = program?.getCurrentDirectory();
+    if (rootDirectory) {
+      return rootDirectory;
+    }
   } catch {
     // Ignore the error if we cannot retrieve a TS program
   }
 
-  // Fall back to the parserOptions.tsconfigRootDir if available, otherwise the eslint working directory
-  if (!rootDirectory) {
-    rootDirectory = context.parserOptions?.tsconfigRootDir ?? context.getCwd?.();
-  }
-
-  return rootDirectory;
+  // Last resort: use ESLint's current working directory
+  return context.getCwd?.();
 }
 
 export function parseImportSpecifierFromExpression(

eslint/eslint-plugin/src/no-external-local-imports.ts

@@ -19,15 +19,15 @@ export const noExternalLocalImportsRule: RuleModule = {
     type: 'problem',
     messages: {
       [MESSAGE_ID]:
-        'The specified import target is not under the root directory. Ensure that ' +
-        'all local import targets are either under the "rootDir" specified in your tsconfig.json (if one ' +
-        'exists) or under the package directory.'
+        'The specified import target "{{ importAbsolutePath }}" is not under the root directory, "{{ rootDirectory }}". Ensure that ' +
+        'all local import targets are either under the "parserOptions.tsconfigRootDir" specified in your eslint.config.js (if one ' +
+        'exists) or else under the folder that contains your tsconfig.json.'
     },
     schema: [],
     docs: {
       description:
-        'Prevents referencing relative imports that are either not under the "rootDir" specified in ' +
-        'the tsconfig.json (if one exists) or not under the package directory.',
+        'Prevents referencing relative imports that are either not under the "parserOptions.tsconfigRootDir" specified in ' +
+        'your eslint.config.js (if one exists) or else not under the folder that contains your tsconfig.json.',
       url: 'https://www.npmjs.com/package/@rushstack/eslint-plugin'
     }
   },
@@ -54,7 +54,11 @@ export const noExternalLocalImportsRule: RuleModule = {
 
       const relativePathToRoot: string = path.relative(importAbsolutePath, rootDirectory);
       if (!_relativePathRegex.test(relativePathToRoot)) {
-        context.report({ node: importExpression, messageId: MESSAGE_ID });
+        context.report({
+          node: importExpression,
+          messageId: MESSAGE_ID,
+          data: { importAbsolutePath, rootDirectory }
+        });
       }
     };
 

heft-plugins/heft-lint-plugin/src/Eslint.ts

@@ -157,7 +157,9 @@ export class Eslint extends LinterBase<TEslint.ESLint.LintResult | TEslintLegacy
       let overrideParserOptions: TEslint.Linter.ParserOptions = {
         programs: [tsProgram],
         // Used by stableStringify and ESLint > 9.28.0
-        toJSON: parserOptionsToJson
+        toJSON: parserOptionsToJson,
+        // ESlint's merge logic for parserOptions is a "replace", so we need to set this again
+        tsconfigRootDir: buildFolderPath
       };
       if (this._eslintPackageVersion.minor < 28) {
         overrideParserOptions = Object.defineProperties(overrideParserOptions, {