feat(plugin-api): prompts.js can now export a function which receives package info

packages/@vue/cli-plugin-typescript/prompts.js

@@ -3,7 +3,7 @@
 
 const { chalk, hasGit } = require('@vue/cli-shared-utils')
 
-module.exports = [
+const prompts = module.exports = [
   {
     name: `classComponent`,
     type: `confirm`,
@@ -38,3 +38,11 @@ module.exports = [
     ]
   }
 ]
+
+// in RC6+ the export can be function, but that would break invoke for RC5 and
+// below, so this is a temporary compatibility hack until we release stable.
+// TODO just export the function in 3.0.0
+module.exports.getPrompts = pkg => {
+  prompts[2].when = () => !('@vue/cli-plugin-eslint' in (pkg.devDependencies || {}))
+  return prompts
+}

packages/@vue/cli/lib/invoke.js

@@ -84,8 +84,14 @@ async function invoke (pluginName, options = {}, context = process.cwd()) {
   // resolve options if no command line options are passed, and the plugin
   // contains a prompt module.
   if (!Object.keys(options).length) {
-    const pluginPrompts = loadModule(`${id}/prompts`, context)
+    let pluginPrompts = loadModule(`${id}/prompts`, context)
     if (pluginPrompts) {
+      if (typeof pluginPrompts === 'function') {
+        pluginPrompts = pluginPrompts(pkg)
+      }
+      if (typeof pluginPrompts.getPrompts === 'function') {
+        pluginPrompts = pluginPrompts.getPrompts(pkg)
+      }
       options = await inquirer.prompt(pluginPrompts)
     }
   }