From d07b7d025f5933710fcb01718617dbdf4bc54c33 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20DUNGLER?= <clementdungler@gmail.com>
Date: Tue, 20 Oct 2020 12:38:32 +0200
Subject: [PATCH] Replace deprecated eslint-loader with eslint-webpack-plugin
 (#9751)

* Replace deprecated eslint-loader by eslint-webpack-plugin

* Update eslintFormatter for eslint-webpack-plugin

* fix: always enable jsx-uses-react

Co-authored-by: Brody McKee <mrmckeb@hotmail.com>
---
 packages/eslint-config-react-app/base.js      |  2 +-
 packages/react-dev-utils/eslintFormatter.js   | 11 ++++++
 .../react-scripts/config/webpack.config.js    | 37 +++++++------------
 packages/react-scripts/package.json           |  2 +-
 4 files changed, 27 insertions(+), 25 deletions(-)

diff --git a/packages/eslint-config-react-app/base.js b/packages/eslint-config-react-app/base.js
index b6acd702ea3..bea4f87b36f 100644
--- a/packages/eslint-config-react-app/base.js
+++ b/packages/eslint-config-react-app/base.js
@@ -51,8 +51,8 @@ module.exports = {
 
   rules: {
     'react/jsx-uses-vars': 'warn',
+    'react/jsx-uses-react': 'warn',
     ...(!hasJsxRuntime && {
-      'react/jsx-uses-react': 'warn',
       'react/react-in-jsx-scope': 'error',
     }),
   },
diff --git a/packages/react-dev-utils/eslintFormatter.js b/packages/react-dev-utils/eslintFormatter.js
index cdef9c70b43..47b111f7568 100644
--- a/packages/react-dev-utils/eslintFormatter.js
+++ b/packages/react-dev-utils/eslintFormatter.js
@@ -7,10 +7,13 @@
 
 'use strict';
 
+const path = require('path');
 const chalk = require('chalk');
 const stripAnsi = require('strip-ansi');
 const table = require('text-table');
 
+const cwd = process.cwd();
+
 function isError(message) {
   if (message.fatal || message.severity === 2) {
     return true;
@@ -18,6 +21,10 @@ function isError(message) {
   return false;
 }
 
+function getRelativePath(filePath) {
+  return path.relative(cwd, filePath);
+}
+
 function formatter(results) {
   let output = '\n';
   let hasErrors = false;
@@ -73,6 +80,10 @@ function formatter(results) {
       },
     });
 
+    // print the filename and relative path
+    output += `${getRelativePath(result.filePath)}\n`;
+
+    // print the errors
     output += `${outputTable}\n\n`;
   });
 
diff --git a/packages/react-scripts/config/webpack.config.js b/packages/react-scripts/config/webpack.config.js
index 31eec3157da..4075824d794 100644
--- a/packages/react-scripts/config/webpack.config.js
+++ b/packages/react-scripts/config/webpack.config.js
@@ -26,6 +26,7 @@ const WorkboxWebpackPlugin = require('workbox-webpack-plugin');
 const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
 const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
 const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent');
+const ESLintPlugin = require('eslint-webpack-plugin');
 const paths = require('./paths');
 const modules = require('./modules');
 const getClientEnvironment = require('./env');
@@ -349,29 +350,6 @@ module.exports = function (webpackEnv) {
       rules: [
         // Disable require.ensure as it's not a standard language feature.
         { parser: { requireEnsure: false } },
-
-        // First, run the linter.
-        // It's important to do this before Babel processes the JS.
-        {
-          test: /\.(js|mjs|jsx|ts|tsx)$/,
-          enforce: 'pre',
-          use: [
-            {
-              options: {
-                cache: true,
-                cwd: paths.appPath,
-                formatter: require.resolve('react-dev-utils/eslintFormatter'),
-                eslintPath: require.resolve('eslint'),
-                resolvePluginsRelativeTo: __dirname,
-                baseConfig: {
-                  extends: [require.resolve('eslint-config-react-app/base')],
-                },
-              },
-              loader: require.resolve('eslint-loader'),
-            },
-          ],
-          include: paths.appSrc,
-        },
         {
           // "oneOf" will traverse all following loaders until one will
           // match the requirements. When no loader matches it will fall
@@ -742,6 +720,19 @@ module.exports = function (webpackEnv) {
           // The formatter is invoked directly in WebpackDevServerUtils during development
           formatter: isEnvProduction ? typescriptFormatter : undefined,
         }),
+      new ESLintPlugin({
+        // Plugin options
+        extensions: ['js', 'mjs', 'jsx', 'ts', 'tsx'],
+        formatter: require.resolve('react-dev-utils/eslintFormatter'),
+        eslintPath: require.resolve('eslint'),
+        context: paths.appSrc,
+        // ESLint class options
+        cwd: paths.appPath,
+        resolvePluginsRelativeTo: __dirname,
+        baseConfig: {
+          extends: [require.resolve('eslint-config-react-app/base')],
+        },
+      }),
     ].filter(Boolean),
     // Some libraries import Node modules but don't use them in the browser.
     // Tell webpack to provide empty mocks for them so importing them works.
diff --git a/packages/react-scripts/package.json b/packages/react-scripts/package.json
index 434864e4359..bc26828a12f 100644
--- a/packages/react-scripts/package.json
+++ b/packages/react-scripts/package.json
@@ -46,13 +46,13 @@
     "dotenv-expand": "5.1.0",
     "eslint": "^7.9.0",
     "eslint-config-react-app": "^5.2.1",
-    "eslint-loader": "^4.0.2",
     "eslint-plugin-flowtype": "^5.2.0",
     "eslint-plugin-import": "^2.22.0",
     "eslint-plugin-jest": "^24.0.1",
     "eslint-plugin-jsx-a11y": "^6.3.1",
     "eslint-plugin-react": "^7.20.6",
     "eslint-plugin-react-hooks": "^4.1.2",
+    "eslint-webpack-plugin": "^2.1.0",
     "file-loader": "6.1.0",
     "fs-extra": "^9.0.0",
     "html-webpack-plugin": "4.4.1",