Add support for Composer v2

.github/workflows/php.yml

@@ -9,31 +9,45 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-versions:
+        php-version:
           - "7.2"
           - "7.3"
           - "7.4"
           - "8.0"
+        composer-dependencies:
+          - 'highest'
     env:
       COMPOSER_DISABLE_XDEBUG_WARN: 1
 
-    name: PHP ${{ matrix.php-versions }} test
+    name: Test PHP ${{ matrix.php-version }}
     steps:
     - name: Checkout
       uses: actions/checkout@v2
-    
+
     - name: Setup PHP version
       uses: shivammathur/setup-php@v2
       with:
-        php-version: ${{ matrix.php-versions }}
+        php-version: ${{ matrix.php-version }}
         coverage: xdebug
-        tools: composer:v1
+        tools: composer:v2
 
-    - name: Install composer dependencies
-      run: composer install --prefer-dist --no-progress
+    - name: Test Composer v1
+      run: composer require --dev --no-update composer/composer:^1.1
+
+    - uses: "ramsey/composer-install@v1"
+      with:
+        dependency-versions: "${{ matrix.composer-dependencies }}"
+
+    - run: composer test
+
+    - name: Test Composer v2
+      run: composer require --dev --no-update composer/composer:^2.0
+
+    - uses: "ramsey/composer-install@v1"
+      with:
+        dependency-versions: "${{ matrix.composer-dependencies }}"
 
-    - name: Run tests
-      run: composer test
+    - run: composer test
 
   ocular-push:
     runs-on: ubuntu-latest
@@ -57,7 +71,7 @@ jobs:
     - name: Run coverage
       run: composer coverage
 
-    - name: Get ocular
+    - name: Get Ocular
       run: wget https://scrutinizer-ci.com/ocular.phar
 
     - name: Upload code coverage
@@ -68,7 +82,7 @@ jobs:
     if: ${{ always() }} && github.repository == 'wikimedia/composer-merge-plugin'
     needs: [run]
     steps:
-    - name: irc push notification
+    - name: IRC push notification
       uses: rectalogic/notify-irc@v1
       if: github.event_name == 'push'
       with:

README.md

@@ -24,15 +24,24 @@ extensions which may be managed via Composer.
 Installation
 ------------
 
-Composer Merge Plugin requires [Composer 1.1.0](https://getcomposer.org/) or
-newer, but doesn't currently support Composer 2.0. See
-[PR #189](https://github.com/wikimedia/composer-merge-plugin/pull/189) for
-current progress.
+Composer Merge Plugin 1.4.x (and older) requires Composer 1.x.
+
+Composer Merge Plugin 1.5.x (and newer) is compatible with both Composer 2.x and 1.x.
 
 ```
 $ composer require wikimedia/composer-merge-plugin
 ```
 
+### Upgrading from Composer 1 to 2
+
+If you are already using Composer Merge Plugin 1.4 (or older) and you are updating the plugin to 1.5 (or newer), it is recommended that you update the plugin first using Composer 1.
+
+If you update the incompatible plugin using Composer 2, the plugin will be ignored:
+
+> The "wikimedia/composer-merge-plugin" plugin was skipped because it requires a Plugin API version ("^1.0") that does not match your Composer installation ("2.0.0"). You may need to run composer update with the "--no-plugins" option.
+
+Consequently, Composer will be unaware of the merged dependencies and will remove them requiring you to run `composer update` again to reinstall merged dependencies.
+
 
 Usage
 -----
@@ -66,13 +75,13 @@ Usage
 ### Updating sub-levels `composer.json` files
 
 
-In order for composer-merge-plugin to install dependencies from updated or newly created sub-level `composer.json` files in your project you need to run the command:
+In order for Composer Merge Plugin to install dependencies from updated or newly created sub-level `composer.json` files in your project you need to run the command:
 
 ```
-$ composer update --lock
+$ composer update
 ```
 
-This will [instruct Composer to recalculate the file hash](https://getcomposer.org/doc/03-cli.md#update) for the top-level `composer.json` thus triggering composer-merge-plugin to look for the sub-level configuration files and update your dependencies.
+This will [instruct Composer to recalculate the file hash](https://getcomposer.org/doc/03-cli.md#update) for the top-level `composer.json` thus triggering Composer Merge Plugin to look for the sub-level configuration files and update your dependencies.
 
 
 Plugin configuration

composer.json

@@ -12,11 +12,11 @@
     "minimum-stability": "dev",
     "prefer-stable": true,
     "require": {
-        "composer-plugin-api": "^1.1",
-        "php": ">=7.2.0"
+        "php": ">=7.2.0",
+        "composer-plugin-api": "^1.1||^2.0"
     },
     "require-dev": {
-        "composer/composer": "^1.1",
+        "composer/composer": "^1.1||^2.0",
         "php-parallel-lint/php-parallel-lint": "~1.1.0",
         "phpunit/phpunit": "^8.5||^9.0",
         "squizlabs/php_codesniffer": "~3.5.4"
@@ -33,7 +33,8 @@
         "class": "Wikimedia\\Composer\\MergePlugin"
     },
     "config": {
-        "optimize-autoloader": true
+        "optimize-autoloader": true,
+        "sort-packages": true
     },
     "scripts": {
         "coverage": [

example/composer.json

@@ -1,8 +1,11 @@
 {
     "repositories": [
         {
-            "type": "vcs",
-            "url": "./.."
+            "type": "path",
+            "url": "./..",
+            "only": [
+                "wikimedia/composer-merge-plugin"
+            ]
         }
     ],
     "require": {

src/Logger.php

@@ -87,7 +87,7 @@ public function warning($message)
      *
      * @param string $message
      */
-    protected function log($message)
+    public function log($message)
     {
         if (method_exists($this->inputOutput, 'writeError')) {
             $this->inputOutput->writeError($message);

src/Merge/ExtraPackage.php

@@ -22,6 +22,9 @@
 use Composer\Package\RootPackage;
 use Composer\Package\RootPackageInterface;
 use Composer\Package\Version\VersionParser;
+use Composer\Plugin\PluginInterface;
+use Composer\Semver\Constraint\MultiConstraint as SemverMultiConstraint;
+use Composer\Semver\Intervals;
 use UnexpectedValueException;
 
 /**
@@ -58,6 +61,11 @@ class ExtraPackage
      */
     protected $package;
 
+    /**
+     * @var array<string, bool> $mergedRequirements
+     */
+    protected $mergedRequirements = array();
+
     /**
      * @var VersionParser $versionParser
      */
@@ -100,6 +108,16 @@ public function getRequires()
             $this->json['extra']['merge-plugin']['require'] : array();
     }
 
+    /**
+     * Get list of merged requirements from this package.
+     *
+     * @return string[]
+     */
+    public function getMergedRequirements()
+    {
+        return array_keys($this->mergedRequirements);
+    }
+
     /**
      * Read the contents of a composer.json style file into an array.
      *
@@ -273,33 +291,89 @@ protected function mergeOrDefer(
         $type,
         array $origin,
         array $merge,
-        $state
+        PluginState $state
     ) {
         if ($state->ignoreDuplicateLinks() && $state->replaceDuplicateLinks()) {
             $this->logger->warning("Both replace and ignore-duplicates are true. These are mutually exclusive.");
             $this->logger->warning("Duplicate packages will be ignored.");
         }
 
-        $dups = array();
         foreach ($merge as $name => $link) {
-            if (isset($origin[$name]) && $state->ignoreDuplicateLinks()) {
-                $this->logger->info("Ignoring duplicate <comment>{$name}</comment>");
-                continue;
-            } elseif (!isset($origin[$name]) || $state->replaceDuplicateLinks()) {
-                $this->logger->info("Merging <comment>{$name}</comment>");
-                $origin[$name] = $link;
+            if (isset($origin[$name])) {
+                if ($state->ignoreDuplicateLinks()) {
+                    $this->logger->info("Ignoring duplicate <comment>{$name}</comment>");
+                    continue;
+                }
+
+                if ($state->replaceDuplicateLinks()) {
+                    $this->logger->info("Replacing <comment>{$name}</comment>");
+                    $this->mergedRequirements[$name] = true;
+                    $origin[$name] = $link;
+                } else {
+                    $this->logger->info("Merging <comment>{$name}</comment>");
+                    $this->mergedRequirements[$name] = true;
+                    $origin[$name] = $this->mergeConstraints($origin[$name], $link, $state);
+                }
             } else {
-                // Defer to solver.
-                $this->logger->info(
-                    "Deferring duplicate <comment>{$name}</comment>"
-                );
-                $dups[] = $link;
+                $this->logger->info("Adding <comment>{$name}</comment>");
+                $this->mergedRequirements[$name] = true;
+                $origin[$name] = $link;
             }
         }
-        $state->addDuplicateLinks($type, $dups);
+
+        if (!$state->isComposer1()) {
+            Intervals::clear();
+        }
+
         return $origin;
     }
 
+    /**
+     * Merge package constraints.
+     *
+     * Adapted from Composer's UpdateCommand::appendConstraintToLink
+     *
+     * @param Link $origin The base package link.
+     * @param Link $merge  The related package link to merge.
+     * @param PluginState $state
+     * @return Link Merged link.
+     */
+    protected function mergeConstraints(Link $origin, Link $merge, PluginState $state)
+    {
+        $parser = $this->versionParser;
+
+        $oldPrettyString = $origin->getConstraint()->getPrettyString();
+        $newPrettyString = $merge->getConstraint()->getPrettyString();
+
+        if ($state->isComposer1()) {
+            $constraintClass = 'Wikimedia\\Composer\\Merge\\MultiConstraint';
+        } else {
+            $constraintClass = 'Composer\\Semver\\Constraint\\MultiConstraint';
+
+            if (Intervals::isSubsetOf($origin->getConstraint(), $merge->getConstraint())) {
+                return $origin;
+            }
+
+            if (Intervals::isSubsetOf($merge->getConstraint(), $origin->getConstraint())) {
+                return $merge;
+            }
+        }
+
+        $newConstraint = $constraintClass::create(array(
+            $origin->getConstraint(),
+            $merge->getConstraint()
+        ), true);
+        $newConstraint->setPrettyString($oldPrettyString.', '.$newPrettyString);
+
+        return new Link(
+            $origin->getSource(),
+            $origin->getTarget(),
+            $newConstraint,
+            $origin->getDescription(),
+            $origin->getPrettyConstraint() . ', ' . $newPrettyString
+        );
+    }
+
     /**
      * Merge autoload or autoload-dev into a RootPackageInterface
      *