From 4b94e55b0360e395d1a1c5dffc936d73497c48ba Mon Sep 17 00:00:00 2001
From: Nicolas Grekas <nicolas.grekas@gmail.com>
Date: Fri, 10 Feb 2023 13:19:41 +0100
Subject: [PATCH] Add extra.plugin-optional to auto-disable plugins in
 non-interactive mode (#11315)

---
 doc/articles/plugins.md               | 14 ++++++++++++++
 src/Composer/Plugin/PluginManager.php |  8 +++++---
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/doc/articles/plugins.md b/doc/articles/plugins.md
index 18d966656..818011887 100644
--- a/doc/articles/plugins.md
+++ b/doc/articles/plugins.md
@@ -332,6 +332,20 @@ in your composer.json to hint to Composer that the plugin should be activated as
 as possible to prevent any bad side-effects from Composer assuming packages are installed
 in another location than they actually are.
 
+### plugin-optional
+
+Because Composer plugins can be used to perform actions which are necessary for installing
+a working application, like modifying which path files get stored in, skipping required
+plugins unintentionally can result in broken applications. So, in non-interactive mode,
+Composer will fail if a new plugin is not listed in ["allow-plugins"](../06-config.md#allow-plugins)
+to force users to decide if they want to execute the plugin, to avoid silent failures.
+
+As of Composer 2.5.3, you can use the setting `{"extra": {"plugin-optional": true}}` on
+your plugin, to tell Composer that skipping the plugin has no catastrophic consequences,
+and it can safely be disabled in non-interactive mode if it is not yet listed in
+"allow-plugins". The next interactive run of Composer will still prompt users to choose if
+they want to enable or disable the plugin.
+
 ## Plugin Autoloading
 
 Due to plugins being loaded by Composer at runtime, and to ensure that plugins which
diff --git a/src/Composer/Plugin/PluginManager.php b/src/Composer/Plugin/PluginManager.php
index fbde18b00..74c33221e 100644
--- a/src/Composer/Plugin/PluginManager.php
+++ b/src/Composer/Plugin/PluginManager.php
@@ -187,7 +187,7 @@ class PluginManager
             }
         }
 
-        if (!$this->isPluginAllowed($package->getName(), $isGlobalPlugin)) {
+        if (!$this->isPluginAllowed($package->getName(), $isGlobalPlugin, $package->getExtra()['plugin-optional'] ?? false)) {
             $this->io->writeError('Skipped loading "'.$package->getName() . '" '.($isGlobalPlugin || $this->runningInGlobalDir ? '(installed globally) ' : '').'as it is not in config.allow-plugins', true, IOInterface::DEBUG);
 
             return;
@@ -370,7 +370,7 @@ class PluginManager
 
         if ($sourcePackage === null) {
             trigger_error('Calling PluginManager::addPlugin without $sourcePackage is deprecated, if you are using this please get in touch with us to explain the use case', E_USER_DEPRECATED);
-        } elseif (!$this->isPluginAllowed($sourcePackage->getName(), $isGlobalPlugin)) {
+        } elseif (!$this->isPluginAllowed($sourcePackage->getName(), $isGlobalPlugin, $sourcePackage->getExtra()['plugin-optional'] ?? false)) {
             $this->io->writeError('Skipped loading "'.get_class($plugin).' from '.$sourcePackage->getName() . '" '.($isGlobalPlugin || $this->runningInGlobalDir ? '(installed globally) ' : '').' as it is not in config.allow-plugins', true, IOInterface::DEBUG);
 
             return;
@@ -656,7 +656,7 @@ class PluginManager
     /**
      * @internal
      */
-    public function isPluginAllowed(string $package, bool $isGlobalPlugin): bool
+    public function isPluginAllowed(string $package, bool $isGlobalPlugin, bool $optional = false): bool
     {
         if ($isGlobalPlugin) {
             $rules = &$this->allowGlobalPluginRules;
@@ -733,6 +733,8 @@ class PluginManager
                         break;
                 }
             }
+        } elseif ($optional) {
+            return false;
         }
 
         throw new PluginBlockedException(