feat: allow disabling auto postcss config loading via postcss.useConfigFile

close #654, close #800

Author: yyx990803

lib/style-compiler/load-postcss-config.js

@@ -7,6 +7,13 @@ function isObject (val) {
 }
 
 module.exports = function loadPostcssConfig (loaderContext, inlineConfig = {}) {
+  if (inlineConfig.useConfigFile === false) {
+    return Promise.resolve({
+      plugins: inlineConfig.plugins || [],
+      options: inlineConfig.options || {}
+    })
+  }
+
   if (process.env.VUE_LOADER_TEST || !loaded) {
     const config = inlineConfig.config || {}
     const ctx = { webpack: loaderContext }