Allow use of --locked with depends and prohibits

src/Composer/Command/BaseDependencyCommand.php

@@ -58,12 +58,34 @@ protected function doExecute(InputInterface $input, OutputInterface $output, boo
         $commandEvent = new CommandEvent(PluginEvents::COMMAND, $this->getName(), $input, $output);
         $composer->getEventDispatcher()->dispatch($commandEvent->getName(), $commandEvent);
 
-        $platformOverrides = $composer->getConfig()->get('platform') ?: array();
-        $installedRepo = new InstalledRepository(array(
-            new RootPackageRepository($composer->getPackage()),
-            $composer->getRepositoryManager()->getLocalRepository(),
-            new PlatformRepository(array(), $platformOverrides),
-        ));
+        $repos = [];
+
+        $repos[] = new RootPackageRepository($composer->getPackage());
+
+        if ($input->getOption('locked')) {
+            $locker = $composer->getLocker();
+
+            if (!$locker->isLocked()) {
+                throw new \UnexpectedValueException('A valid composer.lock file is required to run this command with --locked');
+            }
+
+            $repos[] = $locker->getLockedRepository(true);
+        } else {
+            $localRepo = $composer->getRepositoryManager()->getLocalRepository();
+            $rootPkg = $composer->getPackage();
+
+            if (count($localRepo->getPackages()) === 0 && (count($rootPkg->getRequires()) > 0 || count($rootPkg->getDevRequires()) > 0)) {
+                $output->writeln('<warning>No dependencies installed. Try running composer install or update, or use --locked.</warning>');
+                return 1;
+            }
+
+            $repos[] = $localRepo;
+
+            $platformOverrides = $composer->getConfig()->get('platform') ?: array();
+            $repos[] = new PlatformRepository([], $platformOverrides);
+        }
+
+        $installedRepo = new InstalledRepository($repos);
 
         // Parse package name and constraint
         list($needle, $textConstraint) = array_pad(

src/Composer/Command/DependsCommand.php

@@ -39,6 +39,7 @@ protected function configure(): void
                 new InputArgument(self::ARGUMENT_PACKAGE, InputArgument::REQUIRED, 'Package to inspect', null, $this->suggestInstalledPackage(true)),
                 new InputOption(self::OPTION_RECURSIVE, 'r', InputOption::VALUE_NONE, 'Recursively resolves up to the root package'),
                 new InputOption(self::OPTION_TREE, 't', InputOption::VALUE_NONE, 'Prints the results as a nested tree'),
+                new InputOption('locked', null, InputOption::VALUE_NONE, 'Read dependency information from composer.lock'),
             ))
             ->setHelp(
                 <<<EOT

src/Composer/Command/ProhibitsCommand.php

@@ -40,6 +40,7 @@ protected function configure(): void
                 new InputArgument(self::ARGUMENT_CONSTRAINT, InputArgument::REQUIRED, 'Version constraint, which version you expected to be installed'),
                 new InputOption(self::OPTION_RECURSIVE, 'r', InputOption::VALUE_NONE, 'Recursively resolves up to the root package'),
                 new InputOption(self::OPTION_TREE, 't', InputOption::VALUE_NONE, 'Prints the results as a nested tree'),
+                new InputOption('locked', null, InputOption::VALUE_NONE, 'Read dependency information from composer.lock'),
             ))
             ->setHelp(
                 <<<EOT