Ignore platform reqs if env var or input option present

Author: normanlolx

src/MergePlugin.php

@@ -24,6 +24,7 @@
 use Composer\Plugin\PluginInterface;
 use Composer\Script\Event as ScriptEvent;
 use Composer\Script\ScriptEvents;
+use Symfony\Component\Console\Input\ArgvInput;
 
 /**
  * Composer plugin that allows merging multiple composer.json files.
@@ -373,13 +374,32 @@ public function onPostInstallOrUpdate(ScriptEvent $event)
             $installer->setUpdate(true);
 
             if ($this->state->isComposer1()) {
-                // setUpdateWhitelist() only exists in composer 1.x. Configure as to run phan against composer 2.x
+                // setUpdateWhitelist() only exists in composer 1.x.
+                // Configure as to run phan against composer 2.x
                 // @phan-suppress-next-line PhanUndeclaredMethod
                 $installer->setUpdateWhitelist($requirements);
             } else {
                 $installer->setUpdateAllowList($requirements);
             }
 
+            // Respect --ignore-platform-reqs option from input or
+            // COMPOSER_IGNORE_PLATFORM_REQS environment variable.
+            $input = new ArgvInput();
+            if ($this->state->isComposer1()) {
+                // setIgnorePlatformRequirements only exists in composer 1.x.
+                // Configure as to run phan against composer 2.x
+                // @phan-suppress-next-line PhanUndeclaredMethod
+                $installer->setIgnorePlatformRequirements($input->getOption('ignore-platform-reqs'));
+            } else {
+                $ignore_platform_reqs = getenv('COMPOSER_IGNORE_PLATFORM_REQS') ??
+                    $input->getOption('ignore-platform-reqs');
+                $ignore_platform_reqs =
+                    \Composer\Filter\PlatformRequirementFilter\PlatformRequirementFilterFactory::fromBoolOrList(
+                        $ignore_platform_reqs
+                    );
+                $installer->setPlatformRequirementFilter($ignore_platform_reqs);
+            }
+
             $status = $installer->run();
             if (( $status !== 0 ) && $lockBackup && $lock && !$this->state->isComposer1()) {
                 $this->logger->log(