fix(linter): ensure config manipulations are run only if config is supported (#19035)

packages/js/src/generators/library/library.ts

@@ -267,10 +267,14 @@ export async function addLint(
     // nx-ignore-next-line
   } = require('@nx/linter/src/generators/utils/eslint-file');
 
+  // if config is not supported, we don't need to do anything
+  if (!isEslintConfigSupported(tree)) {
+    return task;
+  }
+
   // Also update the root ESLint config. The lintProjectGenerator will not generate it for root projects.
   // But we need to set the package.json checks.
   if (options.rootProject) {
-    if (isEslintConfigSupported(tree)) {
     addOverrideToLintConfig(tree, '', {
       files: ['*.json'],
       parser: 'jsonc-eslint-parser',
@@ -279,7 +283,6 @@ export async function addLint(
       },
     });
   }
-  }
 
   // If project lints package.json with @nx/dependency-checks, then add ignore files for
   // build configuration files such as vite.config.ts. These config files need to be

packages/linter/src/generators/utils/eslint-file.ts

@@ -55,7 +55,7 @@ export function findEslintFile(tree: Tree, projectRoot = ''): string | null {
 export function isEslintConfigSupported(tree: Tree, projectRoot = ''): boolean {
   const eslintFile = findEslintFile(tree, projectRoot);
   if (!eslintFile) {
-    return;
+    return false;
   }
   return eslintFile.endsWith('.json') || eslintFile.endsWith('.config.js');
 }
@@ -233,6 +233,9 @@ export function lintConfigHasOverride(
   lookup: (override: Linter.ConfigOverride<Linter.RulesRecord>) => boolean,
   checkBaseConfig = false
 ): boolean {
+  if (!isEslintConfigSupported(tree, root)) {
+    return false;
+  }
   const isBase =
     checkBaseConfig && findEslintFile(tree, root).includes('.base');
   if (useFlatConfig(tree)) {
@@ -248,9 +251,7 @@ export function lintConfigHasOverride(
       isBase ? baseEsLintConfigFile : '.eslintrc.json'
     );
 
-    return tree.exists(fileName)
-      ? readJson(tree, fileName).overrides?.some(lookup) || false
-      : false;
+    return readJson(tree, fileName).overrides?.some(lookup) || false;
   }
 }
 

packages/linter/src/migrations/update-16-8-0-add-ignored-files/update-16-8-0-add-ignored-files.spec.ts

@@ -8,6 +8,7 @@ describe('update-16-8-0-add-ignored-files migration', () => {
 
   beforeEach(() => {
     tree = createTreeWithEmptyWorkspace();
+    tree.write('.eslintrc.json', '{}');
   });
 
   it('should run successfully when eslint config is not present', async () => {

packages/linter/src/migrations/update-16-8-0-add-ignored-files/update-16-8-0-add-ignored-files.ts

@@ -2,6 +2,7 @@ import { getProjects, Tree } from '@nx/devkit';
 import { forEachExecutorOptions } from '@nx/devkit/src/generators/executor-options-utils';
 import {
   findEslintFile,
+  isEslintConfigSupported,
   lintConfigHasOverride,
   updateOverrideInLintConfig,
 } from '../../generators/utils/eslint-file';
@@ -16,7 +17,12 @@ export default function update(tree: Tree) {
   const addIgnorePattern =
     (ignorePattern: string) => (_options: unknown, projectName: string) => {
       const project = projects.get(projectName);
-      if (!findEslintFile(tree, project.root)) return;
+      if (
+        !findEslintFile(tree, project.root) ||
+        !isEslintConfigSupported(tree)
+      ) {
+        return;
+      }
       if (
         lintConfigHasOverride(
           tree,