Clarify temporary constraint usages and throw if an unresolvable cons…

…traint is provided

doc/03-cli.md

@@ -176,8 +176,9 @@ you can skip `--with` and instead use constraints with the partial update syntax
 php composer.phar update vendor/package:2.0.1 vendor/package2:3.0.*
 ```
 
-The custom constraint has to be a subset of the existing constraint you have,
-and this feature is only available for your root package dependencies.
+> **Note:** For packages also required in your composer.json the custom constraint
+> must be a subset of the existing constraint. The composer.json constraints still
+> apply and the composer.json is not modified by these temporary update constraints.
 
 
 ### Options

src/Composer/Command/UpdateCommand.php

@@ -21,6 +21,7 @@
 use Composer\Plugin\CommandEvent;
 use Composer\Plugin\PluginEvents;
 use Composer\Package\Version\VersionParser;
+use Composer\Semver\Intervals;
 use Composer\Util\HttpDownloader;
 use Composer\Advisory\Auditor;
 use Symfony\Component\Console\Helper\Table;
@@ -147,16 +148,22 @@ protected function execute(InputInterface $input, OutputInterface $output)
             }
         }
 
+        $rootPackage = $composer->getPackage();
+        $rootPackage->setReferences(RootPackageLoader::extractReferences($reqs, $rootPackage->getReferences()));
+        $rootPackage->setStabilityFlags(RootPackageLoader::extractStabilityFlags($reqs, $rootPackage->getMinimumStability(), $rootPackage->getStabilityFlags()));
+
         $parser = new VersionParser;
         $temporaryConstraints = [];
+        $rootRequirements = array_merge($rootPackage->getRequires(), $rootPackage->getDevRequires());
         foreach ($reqs as $package => $constraint) {
-            $temporaryConstraints[strtolower($package)] = $parser->parseConstraints($constraint);
+            $package = strtolower($package);
+            $parsedConstraint = $parser->parseConstraints($constraint);
+            $temporaryConstraints[$package] = $parsedConstraint;
+            if (isset($rootRequirements[$package]) && !Intervals::haveIntersections($parsedConstraint, $rootRequirements[$package]->getConstraint())) {
+                throw new \InvalidArgumentException('The temporary constraint "'.$constraint.'" for "'.$package.'" must be a subset of the constraint in your composer.json ('.$rootRequirements[$package]->getPrettyConstraint().')');
+            }
         }
 
-        $rootPackage = $composer->getPackage();
-        $rootPackage->setReferences(RootPackageLoader::extractReferences($reqs, $rootPackage->getReferences()));
-        $rootPackage->setStabilityFlags(RootPackageLoader::extractStabilityFlags($reqs, $rootPackage->getMinimumStability(), $rootPackage->getStabilityFlags()));
-
         if ($input->getOption('interactive')) {
             $packages = $this->getPackagesInteractively($io, $input, $output, $composer, $packages);
         }