Fix ESLint output formatting

The `formatter` option is incompatible with with `thread-loader`.
The `formatter` option previously accepted a function which was lost during JSON serialization.

Author: Timer

config/webpack.config.dev.js

@@ -15,7 +15,6 @@ const HtmlWebpackPlugin = require('html-webpack-plugin');
 const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
 const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
 const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
-const eslintFormatter = require('react-dev-utils/eslintFormatter');
 const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
 const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent');
 const getClientEnvironment = require('./env');
@@ -181,7 +180,7 @@ module.exports = {
         use: [
           {
             options: {
-              formatter: eslintFormatter,
+              formatter: require.resolve('react-dev-utils/eslintFormatter'),
               eslintPath: require.resolve('eslint'),
               baseConfig: {
                 extends: [require.resolve('eslint-config-react-app')],
@@ -225,7 +224,7 @@ module.exports = {
               {
                 loader: require.resolve('thread-loader'),
                 options: {
-                  poolTimeout: Infinity // keep workers alive for more effective watch mode
+                  poolTimeout: Infinity, // keep workers alive for more effective watch mode
                 },
               },
               {
@@ -266,7 +265,7 @@ module.exports = {
               {
                 loader: require.resolve('thread-loader'),
                 options: {
-                  poolTimeout: Infinity // keep workers alive for more effective watch mode
+                  poolTimeout: Infinity, // keep workers alive for more effective watch mode
                 },
               },
               {

config/webpack.config.prod.js

@@ -18,7 +18,6 @@ const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
 const ManifestPlugin = require('webpack-manifest-plugin');
 const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
 const SWPrecacheWebpackPlugin = require('sw-precache-webpack-plugin');
-const eslintFormatter = require('react-dev-utils/eslintFormatter');
 const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
 const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent');
 const paths = require('./paths');
@@ -219,7 +218,7 @@ module.exports = {
         use: [
           {
             options: {
-              formatter: eslintFormatter,
+              formatter: require.resolve('react-dev-utils/eslintFormatter'),
               eslintPath: require.resolve('eslint'),
               // TODO: consider separate config for production,
               // e.g. to enable no-console and no-debugger only in production.

package.json

@@ -38,7 +38,7 @@
     "dotenv-expand": "4.2.0",
     "eslint": "4.19.1",
     "eslint-config-react-app": "^2.1.0",
-    "eslint-loader": "2.0.0",
+    "eslint-loader": "Timer/eslint-loader#e242479990d520213425a0180e5c749b2e71c1ce",
     "eslint-plugin-flowtype": "2.46.3",
     "eslint-plugin-import": "2.11.0",
     "eslint-plugin-jsx-a11y": "6.0.3",