From fec5eeef8dec4ef872f7f0ccfeb8f0a8dc94c95d Mon Sep 17 00:00:00 2001
From: Antoine Makdessi <amakdessi@me.com>
Date: Thu, 9 Dec 2021 10:46:47 +0100
Subject: [PATCH] Add warning that Composer 1 is deprecated in install command
 (#9826)

---
 src/Composer/Command/InstallCommand.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Composer/Command/InstallCommand.php b/src/Composer/Command/InstallCommand.php
index 32fb1bdc6..231321406 100644
--- a/src/Composer/Command/InstallCommand.php
+++ b/src/Composer/Command/InstallCommand.php
@@ -12,6 +12,7 @@
 
 namespace Composer\Command;
 
+use Composer\Composer;
 use Composer\Installer;
 use Composer\Plugin\CommandEvent;
 use Composer\Plugin\PluginEvents;
@@ -85,6 +86,8 @@ EOT
             $io->writeError('<warning>You are using the deprecated option "dev". Dev packages are installed by default now.</warning>');
         }
 
+        $io->writeError('<warning>You are using Composer 1 which is deprecated. You should upgrade to Composer 2, see https://blog.packagist.com/deprecating-composer-1-support/</warning>');
+
         $composer = $this->getComposer(true, $input->getOption('no-plugins'));
         $composer->getDownloadManager()->setOutputProgress(!$input->getOption('no-progress'));