fix: avoid deepmerge on project config

Author: yyx990803

packages/@vue/cli-service/lib/Service.js

@@ -4,7 +4,6 @@ const debug = require('debug')
 const chalk = require('chalk')
 const readPkg = require('read-pkg')
 const merge = require('webpack-merge')
-const deepMerge = require('deepmerge')
 const Config = require('webpack-chain')
 const PluginAPI = require('./PluginAPI')
 const loadEnv = require('./util/loadEnv')
@@ -21,10 +20,9 @@ module.exports = class Service {
     this.devServerConfigFns = []
     this.commands = {}
     this.pkg = this.resolvePkg(pkg)
-    this.projectOptions = deepMerge(
-      defaults(),
-      this.loadProjectOptions(projectOptions)
-    )
+
+    const userOptions = this.loadProjectOptions(projectOptions)
+    this.projectOptions = Object.assign(defaults(), userOptions)
 
     debug('vue:project-config')(this.projectOptions)
 

packages/@vue/cli-service/lib/config/css.js

@@ -15,7 +15,13 @@ module.exports = (api, options) => {
     const ExtractTextPlugin = require('extract-text-webpack-plugin')
 
     const isProd = process.env.NODE_ENV === 'production'
-    const userOptions = options.css || {}
+    const defaultOptions = {
+      extract: true,
+      modules: false,
+      sourceMap: false,
+      loaderOptions: {}
+    }
+    const userOptions = Object.assign(defaultOptions, options.css || {})
     const extract = isProd && userOptions.extract !== false
 
     // check if the project has a valid postcss config

packages/@vue/cli-service/lib/options.js

@@ -22,8 +22,16 @@ const schema = createSchema(joi => joi.object({
     })
   }),
   devServer: joi.object(),
+
   // known options from offical plugins
-  lintOnSave: joi.boolean()
+  lintOnSave: joi.boolean(),
+
+  // webpack
+  chainWebpack: joi.func(),
+  configureWebpack: joi.alternatives().try(
+    joi.object(),
+    joi.func()
+  )
 }))
 
 exports.validate = options => validate(
@@ -58,12 +66,10 @@ exports.defaults = () => ({
   dll: false,
 
   css: {
-    // boolean | Object, extract css?
-    extract: true,
-    // apply css modules to CSS files that doesn't end with .module.css?
-    modules: false,
-    sourceMap: false,
-    loaderOptions: {}
+    // extract: true,
+    // modules: false,
+    // sourceMap: false,
+    // loaderOptions: {}
   },
 
   // whether to use eslint-loader

packages/@vue/cli-service/package.json

@@ -32,7 +32,6 @@
     "chalk": "^2.3.0",
     "copy-webpack-plugin": "^4.3.1",
     "css-loader": "^0.28.9",
-    "deepmerge": "^2.0.1",
     "escape-string-regexp": "^1.0.5",
     "extract-text-webpack-plugin": "^3.0.2",
     "file-loader": "^1.1.6",