From d5ad6475210483e6e613fe78d280d95af5794da8 Mon Sep 17 00:00:00 2001
From: Haoqun Jiang <haoqunjiang@gmail.com>
Date: Wed, 14 Oct 2020 16:15:14 +0800
Subject: [PATCH] fix: npm 7 compat by turning on `legacy-peer-deps` flag

fixes #5958
---
 packages/@vue/cli/lib/util/ProjectPackageManager.js | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/packages/@vue/cli/lib/util/ProjectPackageManager.js b/packages/@vue/cli/lib/util/ProjectPackageManager.js
index 0cc7588be5..2531cf3457 100644
--- a/packages/@vue/cli/lib/util/ProjectPackageManager.js
+++ b/packages/@vue/cli/lib/util/ProjectPackageManager.js
@@ -134,6 +134,10 @@ class PackageManager {
 
         this.needsNpmInstallFix = true
       }
+
+      if (semver.gte(npmVersion, '7.0.0')) {
+        this.needsPeerDepsFix = true
+      }
     }
 
     if (!SUPPORTED_PACKAGE_MANAGERS.includes(this.bin)) {
@@ -374,7 +378,7 @@ class PackageManager {
       return
     }
 
-    return await this.runCommand('install')
+    return await this.runCommand('install', this.needsPeerDepsFix ? ['--legacy-peer-deps'] : [])
   }
 
   async add (packageName, {
@@ -390,6 +394,10 @@ class PackageManager {
       }
     }
 
+    if (this.needsPeerDepsFix) {
+      args.push('--legacy-peer-deps')
+    }
+
     return await this.runCommand('add', [packageName, ...args])
   }