From 4897e55b0dc821c98c2392e2e47e7c84bb6dfb14 Mon Sep 17 00:00:00 2001
From: Haoqun Jiang <haoqunjiang@gmail.com>
Date: Fri, 31 Jan 2020 03:38:39 +0800
Subject: [PATCH] fix: vue-template-compiler can be optional if
 @vue/compiler-sfc presents (#5123)

---
 packages/@vue/cli-service/lib/config/base.js | 21 ++++++++++++++------
 packages/@vue/cli-service/package.json       |  3 +++
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/packages/@vue/cli-service/lib/config/base.js b/packages/@vue/cli-service/lib/config/base.js
index 5081e2f749..ab8c89b023 100644
--- a/packages/@vue/cli-service/lib/config/base.js
+++ b/packages/@vue/cli-service/lib/config/base.js
@@ -73,12 +73,21 @@ module.exports = (api, options) => {
     // js is handled by cli-plugin-babel ---------------------------------------
 
     // vue-loader --------------------------------------------------------------
-    const vueLoaderCacheConfig = api.genCacheConfig('vue-loader', {
-      'vue-loader': require('vue-loader/package.json').version,
-      /* eslint-disable-next-line node/no-extraneous-require */
-      '@vue/component-compiler-utils': require('@vue/component-compiler-utils/package.json').version,
-      'vue-template-compiler': require('vue-template-compiler/package.json').version
-    })
+    const vueLoaderCacheIdentifier = {
+      'vue-loader': require('vue-loader/package.json').version
+    }
+
+    // The following 2 deps are sure to exist in Vue 2 projects.
+    // But once we switch to Vue 3, they're no longer mandatory.
+    // (In Vue 3 they are replaced by @vue/compiler-sfc)
+    // So wrap them in a try catch block.
+    try {
+      vueLoaderCacheIdentifier['@vue/component-compiler-utils'] =
+        require('@vue/component-compiler-utils/package.json').version
+      vueLoaderCacheIdentifier['vue-template-compiler'] =
+        require('vue-template-compiler/package.json').version
+    } catch (e) {}
+    const vueLoaderCacheConfig = api.genCacheConfig('vue-loader', vueLoaderCacheIdentifier)
 
     webpackConfig.module
       .rule('vue')
diff --git a/packages/@vue/cli-service/package.json b/packages/@vue/cli-service/package.json
index 5a1bf70ae4..c368fdf932 100644
--- a/packages/@vue/cli-service/package.json
+++ b/packages/@vue/cli-service/package.json
@@ -94,6 +94,9 @@
     },
     "stylus-loader": {
       "optional": true
+    },
+    "vue-template-compiler": {
+      "optional": true
     }
   },
   "devDependencies": {