Add error when composer show --direct <transient-dependency> is used to show a dependency which is not direct, fixes #11728

src/Composer/Command/ShowCommand.php

@@ -299,6 +299,12 @@ EOT
         } elseif (null !== $packageFilter && !str_contains($packageFilter, '*')) {
             [$package, $versions] = $this->getPackage($installedRepo, $repos, $packageFilter, $input->getArgument('version'));
 
+            if (isset($package) && $input->getOption('direct')) {
+                if (!in_array($package->getName(), $this->getRootRequires(), true)) {
+                    throw new \InvalidArgumentException('Package "' . $package->getName() . '" is installed but not a direct dependent of the root package.');
+                }
+            }
+
             if (!isset($package)) {
                 $options = $input->getOptions();
                 $hint = '';

tests/Composer/Test/Command/ShowCommandTest.php

@@ -18,6 +18,7 @@ use Composer\Pcre\Regex;
 use Composer\Repository\PlatformRepository;
 use Composer\Test\TestCase;
 use DateTimeImmutable;
+use InvalidArgumentException;
 
 class ShowCommandTest extends TestCase
 {
@@ -298,6 +299,23 @@ Transitive dependencies not required in composer.json:
 vendor/package 1.1.0 <highlight>! 1.2.0</highlight>", trim($appTester->getDisplay(true)));
     }
 
+    public function testShowDirectWithNameOnlyShowsDirectDependents(): void
+    {
+        self::expectException(InvalidArgumentException::class);
+        self::expectExceptionMessage('Package "vendor/package" is installed but not a direct dependent of the root package.');
+
+        $this->initTempComposer([
+            'repositories' => [],
+        ]);
+
+        $this->createInstalledJson([
+            self::getPackage('vendor/package', '1.0.0'),
+        ]);
+
+        $appTester = $this->getApplicationTester();
+        $appTester->run(['command' => 'show', '--direct' => true, 'package' => 'vendor/package']);
+    }
+
     public function testShowPlatformOnlyShowsPlatformPackages(): void
     {
         $this->initTempComposer([