From 4164b302367ca890066dd4a67c032b129704972a Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Tue, 13 Sep 2022 14:49:25 +0200
Subject: [PATCH] Fix show --platform regression failing if no composer.json
 exists, fixes #11046

---
 src/Composer/Command/ShowCommand.php            |  7 ++++++-
 tests/Composer/Test/Command/ShowCommandTest.php | 14 ++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/Composer/Command/ShowCommand.php b/src/Composer/Command/ShowCommand.php
index 2ec21c33fcb6..47ef25de9bb7 100644
--- a/src/Composer/Command/ShowCommand.php
+++ b/src/Composer/Command/ShowCommand.php
@@ -677,7 +677,12 @@ private function printPackages(IOInterface $io, array $packages, string $indent,
      */
     protected function getRootRequires(): array
     {
-        $rootPackage = $this->requireComposer()->getPackage();
+        $composer = $this->tryComposer();
+        if ($composer === null) {
+            return [];
+        }
+
+        $rootPackage = $composer->getPackage();
 
         return array_map(
             'strtolower',
diff --git a/tests/Composer/Test/Command/ShowCommandTest.php b/tests/Composer/Test/Command/ShowCommandTest.php
index 9c9880203448..540faeabab7f 100644
--- a/tests/Composer/Test/Command/ShowCommandTest.php
+++ b/tests/Composer/Test/Command/ShowCommandTest.php
@@ -192,6 +192,20 @@ public function testShowPlatformOnlyShowsPlatformPackages(): void
         }
     }
 
+    public function testShowPlatformWorksWithoutComposerJson(): void
+    {
+        $this->initTempComposer([]);
+        unlink('./composer.json');
+        unlink('./auth.json');
+
+        $appTester = $this->getApplicationTester();
+        $appTester->run(['command' => 'show', '-p' => true]);
+        $output = trim($appTester->getDisplay(true));
+        foreach (Regex::matchAll('{^(\w+)}m', $output)->matches as $m) {
+            self::assertTrue(PlatformRepository::isPlatformPackage((string) $m[1]));
+        }
+    }
+
     public function testOutdatedWithZeroMajor(): void
     {
         $this->initTempComposer([