Add compatibility with PHP 8 (see #2535)

Description
-----------

See #2263 and #2291

### TODO

* [x] Fix the tests.
* [x] Wait if sebastianbergmann/php-code-coverage#837 gets merged and then use PHPUnit 8.5 for all PHP versions.
* [ ] <del>Click through the back end and front end and fix all warnings.</del>

Commits
-------

8ad6149 Add PHP 8.0 to the CI chain
7b8729e Fix the unit and functional tests
47c14db Use 127.0.0.1 instead of localhost in the functional tests
938836c Always set the ACCEPT_LANGUAGE header in the functional tests
a4199ec Use PHPUnit 8.5 for all PHP versions
7ffbd26 Adjust the error level in PHP 8
4ce6b27 Merge branch '4.9' into fix/php8

.github/workflows/ci.yml

@@ -19,16 +19,16 @@ jobs:
             - name: Setup PHP
               uses: shivammathur/setup-php@v2
               with:
-                  php-version: 7.3
+                  php-version: 7.4
                   extensions: dom, fileinfo, filter, gd, hash, intl, json, mbstring, pcre, pdo, zlib
-                  tools: prestissimo, flex
+                  tools: flex
                   coverage: pcov
 
             - name: Checkout
               uses: actions/checkout@v1
 
             - name: Install the dependencies
-              run: composer install --no-interaction --no-suggest
+              run: composer install --no-interaction
 
             - name: Generate the coverage report
               run: php -d pcov.enabled=1 vendor/bin/phpunit --testsuite=coverage --coverage-clover=clover.xml --colors=always
@@ -47,16 +47,16 @@ jobs:
             - name: Setup PHP
               uses: shivammathur/setup-php@v2
               with:
-                  php-version: 7.3
+                  php-version: 7.4
                   extensions: dom, fileinfo, filter, gd, hash, intl, json, mbstring, pcre, pdo, zlib
-                  tools: prestissimo, flex
+                  tools: flex
                   coverage: none
 
             - name: Checkout
               uses: actions/checkout@v1
 
             - name: Install the dependencies
-              run: composer install --no-interaction --no-suggest
+              run: composer install --no-interaction
 
             - name: Check the coding style
               run: |
@@ -87,7 +87,39 @@ jobs:
               with:
                   php-version: ${{ matrix.php }}
                   extensions: dom, fileinfo, filter, gd, hash, intl, json, mbstring, pcre, pdo_mysql, zlib
-                  tools: prestissimo, flex
+                  tools: flex
+                  coverage: none
+
+            - name: Initialize the database
+              run: |
+                  sudo /etc/init.d/mysql start
+                  mysql -uroot -proot -e "CREATE database contao_test"
+
+            - name: Checkout
+              uses: actions/checkout@v1
+
+            - name: Install the dependencies
+              run: composer install --no-interaction
+
+            - name: Run the unit tests
+              run: vendor/bin/phpunit --colors=always
+
+            - name: Run the functional tests
+              run: vendor/bin/phpunit --testsuite=functional --colors=always
+              env:
+                  DATABASE_URL: mysql://root:root@127.0.0.1:3306/contao_test
+
+    php8:
+        name: PHP 8.0
+        runs-on: ubuntu-latest
+        if: github.event_name != 'push'
+        steps:
+            - name: Setup PHP
+              uses: shivammathur/setup-php@v2
+              with:
+                  php-version: 8.0
+                  extensions: dom, fileinfo, filter, gd, hash, intl, json, mbstring, pcre, pdo_mysql, zlib
+                  tools: flex
                   coverage: none
 
             - name: Initialize the database
@@ -99,15 +131,15 @@ jobs:
               uses: actions/checkout@v1
 
             - name: Install the dependencies
-              run: composer install --no-interaction --no-suggest
+              run: composer install --ignore-platform-reqs --no-interaction
 
             - name: Run the unit tests
               run: vendor/bin/phpunit --colors=always
 
             - name: Run the functional tests
               run: vendor/bin/phpunit --testsuite=functional --colors=always
               env:
-                  DATABASE_URL: mysql://root:root@localhost:3306/contao_test
+                  DATABASE_URL: mysql://root:root@127.0.0.1:3306/contao_test
 
     prefer-lowest:
         name: Prefer Lowest
@@ -119,7 +151,7 @@ jobs:
               with:
                   php-version: 7.3
                   extensions: dom, fileinfo, filter, gd, hash, intl, json, mbstring, pcre, pdo_mysql, zlib
-                  tools: prestissimo, flex
+                  tools: flex
                   coverage: none
 
             - name: Initialize the database
@@ -131,15 +163,15 @@ jobs:
               uses: actions/checkout@v1
 
             - name: Install the dependencies
-              run: composer update --prefer-lowest --prefer-stable --no-interaction --no-suggest
+              run: composer update --prefer-lowest --prefer-stable --no-interaction
 
             - name: Run the unit tests
               run: vendor/bin/phpunit --colors=always
 
             - name: Run the functional tests
               run: vendor/bin/phpunit --testsuite=functional --colors=always
               env:
-                  DATABASE_URL: mysql://root:root@localhost:3306/contao_test
+                  DATABASE_URL: mysql://root:root@127.0.0.1:3306/contao_test
 
     bundles:
         name: Bundles
@@ -149,9 +181,9 @@ jobs:
             - name: Setup PHP
               uses: shivammathur/setup-php@v2
               with:
-                  php-version: 7.3
+                  php-version: 7.4
                   extensions: dom, fileinfo, filter, gd, hash, intl, json, mbstring, pcre, pdo, zlib
-                  tools: prestissimo, flex
+                  tools: flex
                   coverage: none
 
             - name: Checkout
@@ -174,7 +206,7 @@ jobs:
                           }
                           file_put_contents(__DIR__."/composer.json", json_encode($data, JSON_UNESCAPED_SLASHES));
                       '
-                      COMPOSER_ROOT_VERSION=dev-${{ env.GITHUB_SHA }} composer install --no-interaction --no-suggest
+                      COMPOSER_ROOT_VERSION=dev-${{ env.GITHUB_SHA }} composer install --no-interaction
                       vendor/bin/phpunit --colors=always
                       cd ..
                   done
@@ -187,10 +219,10 @@ jobs:
             - name: Setup PHP
               uses: shivammathur/setup-php@v2
               with:
-                  php-version: 7.3
+                  php-version: 7.4
                   extensions: dom, fileinfo, filter, gd, hash, intl, json, mbstring, mysqli, pcre, pdo_mysql, zlib
                   ini-values: memory_limit=1G
-                  tools: prestissimo, flex
+                  tools: flex
                   coverage: none
 
             - name: Adjust the Git autocrlf setting
@@ -200,7 +232,7 @@ jobs:
               uses: actions/checkout@v1
 
             - name: Install the dependencies
-              run: composer install --no-interaction --no-suggest --no-progress
+              run: composer install --no-interaction --no-progress
 
             - name: Run the unit tests
               run: vendor/bin/phpunit.bat --colors=always
@@ -213,9 +245,8 @@ jobs:
             - name: Setup PHP
               uses: shivammathur/setup-php@v2
               with:
-                  php-version: 7.3
+                  php-version: 7.4
                   extensions: json, zlib
-                  tools: prestissimo
                   coverage: none
 
             - name: Checkout
@@ -224,7 +255,7 @@ jobs:
             - name: Install the dependencies
               run: |
                   composer global require contao/monorepo-tools:dev-master
-                  composer install --no-interaction --no-suggest
+                  composer install --no-interaction
 
             - name: Validate the composer.json files
               run: $HOME/.composer/vendor/bin/monorepo-tools composer-json --validate --ansi
@@ -237,9 +268,8 @@ jobs:
             - name: Setup PHP
               uses: shivammathur/setup-php@v2
               with:
-                  php-version: 7.3
+                  php-version: 7.4
                   extensions: json, zlib
-                  tools: prestissimo
                   coverage: none
 
             - name: Checkout

calendar-bundle/composer.json

@@ -15,7 +15,7 @@
         }
     ],
     "require": {
-        "php": "^7.2",
+        "php": "^7.2 || ^8.0",
         "contao/core-bundle": "self.version",
         "friendsofsymfony/http-cache": "^2.4",
         "patchwork/utf8": "^1.2",
@@ -32,7 +32,7 @@
     "require-dev": {
         "contao/manager-plugin": "^2.3.1",
         "contao/test-case": "^4.0",
-        "phpunit/phpunit": "^8.4",
+        "phpunit/phpunit": "^8.5",
         "symfony/http-client": "4.4.*",
         "symfony/phpunit-bridge": "4.4.*"
     },

comments-bundle/composer.json

@@ -15,7 +15,7 @@
         }
     ],
     "require": {
-        "php": "^7.2",
+        "php": "^7.2 || ^8.0",
         "contao/core-bundle": "self.version",
         "patchwork/utf8": "^1.2",
         "symfony/http-kernel": "4.4.*"

composer.json

@@ -15,7 +15,7 @@
         }
     ],
     "require": {
-        "php": "^7.2",
+        "php": "^7.2 || ^8.0",
         "ext-dom": "*",
         "ext-gd": "*",
         "ext-hash": "*",
@@ -148,7 +148,7 @@
         "contao/test-case": "^4.0",
         "doctrine/event-manager": "^1.0",
         "monolog/monolog": "^1.24",
-        "phpunit/phpunit": "^8.4",
+        "phpunit/phpunit": "^8.5",
         "psr/event-dispatcher": "^1.0",
         "slam/phpstan-extensions": "^5.0",
         "symfony/browser-kit": "4.4.*",

core-bundle/composer.json

@@ -15,7 +15,7 @@
         }
     ],
     "require": {
-        "php": "^7.2",
+        "php": "^7.2 || ^8.0",
         "ext-dom": "*",
         "ext-gd": "*",
         "ext-hash": "*",
@@ -120,7 +120,7 @@
         "doctrine/event-manager": "^1.0",
         "lexik/maintenance-bundle": "^2.1.5",
         "monolog/monolog": "^1.24",
-        "phpunit/phpunit": "^8.4",
+        "phpunit/phpunit": "^8.5",
         "psr/event-dispatcher": "^1.0",
         "symfony/browser-kit": "4.4.*",
         "symfony/http-client": "4.4.*",

core-bundle/src/DependencyInjection/Configuration.php

@@ -57,10 +57,10 @@ public function getConfigTreeBuilder(): TreeBuilder
                     ->defaultValue('%kernel.secret%')
                 ->end()
                 ->integerNode('error_level')
-                    ->info('The error reporting level set when the framework is initialized. Defaults to E_ALL & ~E_NOTICE & ~E_DEPRECATED & ~E_USER_DEPRECATED.')
+                    ->info('The error reporting level set when the framework is initialized.')
                     ->min(-1)
                     ->max(32767)
-                    ->defaultValue(E_ALL & ~E_NOTICE & ~E_DEPRECATED & ~E_USER_DEPRECATED)
+                    ->defaultValue($this->getErrorLevel())
                 ->end()
                 ->variableNode('localconfig')
                     ->info('Allows to set TL_CONFIG variables, overriding settings stored in localconfig.php. Changes in the Contao back end will not have any effect.')
@@ -456,6 +456,19 @@ private function canonicalize(string $value): string
         return rtrim(implode('', $resolved), '\/');
     }
 
+    private function getErrorLevel(): int
+    {
+        if (PHP_MAJOR_VERSION < 8) {
+            return E_ALL & ~E_NOTICE & ~E_DEPRECATED & ~E_USER_DEPRECATED;
+        }
+
+        // Disable E_WARNING in PHP 8, because a number of notices have been
+        // converted into warnings and now cause a lot of issues with undefined
+        // array keys and undefined properties.
+        // @see https://www.php.net/manual/de/migration80.incompatible.php
+        return E_ALL & ~E_WARNING & ~E_NOTICE & ~E_DEPRECATED & ~E_USER_DEPRECATED;
+    }
+
     /**
      * @return array<string>
      */

core-bundle/src/Resources/contao/library/Contao/DcaExtractor.php

@@ -406,7 +406,13 @@ protected function createExtract()
 				// Check whether there is a relation (see #6524)
 				if (isset($config['relation']))
 				{
-					$table = substr($config['foreignKey'], 0, strrpos($config['foreignKey'], '.'));
+					$table = null;
+
+					if (isset($config['foreignKey']))
+					{
+						$table = substr($config['foreignKey'], 0, strrpos($config['foreignKey'], '.'));
+					}
+
 					$arrRelations[$field] = array_merge(array('table'=>$table, 'field'=>'id'), $config['relation']);
 
 					// Store the field delimiter if the related IDs are stored in CSV format (see #257)

core-bundle/src/Resources/contao/library/Contao/GdImage.php

@@ -129,15 +129,15 @@ public function getResource()
 	/**
 	 * Set the GD resource handle
 	 *
-	 * @param resource $gdResource The GD resource handle
+	 * @param \GdImage|resource $gdResource The GD resource handle
 	 *
 	 * @return static
 	 *
 	 * @throws \InvalidArgumentException If $gdResource is not a GD resource
 	 */
 	public function setResource($gdResource)
 	{
-		if (!\is_resource($gdResource) || get_resource_type($gdResource) !== 'gd')
+		if (!$gdResource instanceof \GdImage && (!\is_resource($gdResource) || get_resource_type($gdResource) !== 'gd'))
 		{
 			throw new \InvalidArgumentException('$gdResource is not a valid GD resource');
 		}
@@ -397,4 +397,8 @@ public function __destruct()
 	}
 }
 
-class_alias(GdImage::class, 'GdImage');
+// PHP 8.0 compatibility
+if (!class_exists('GdImage'))
+{
+	class_alias(GdImage::class, 'GdImage');
+}

core-bundle/src/Resources/contao/library/Contao/InsertTags.php

@@ -105,6 +105,12 @@ protected function doReplace($strBuffer, $blnCache)
 		for ($_rit=0, $_cnt=\count($tags); $_rit<$_cnt; $_rit+=2)
 		{
 			$strBuffer .= $tags[$_rit];
+
+			if (!isset($tags[$_rit+1]))
+			{
+				continue;
+			}
+
 			$strTag = $tags[$_rit+1];
 
 			// Skip empty tags

core-bundle/src/Resources/contao/library/Contao/Widget.php

@@ -780,7 +780,7 @@ protected function getPost($strKey)
 				break;
 			}
 
-			$varValue = $varValue[$part];
+			$varValue = $varValue[$part] ?? null;
 		}
 
 		return $varValue;

core-bundle/tests/Contao/Database/ResultTest.php

@@ -15,6 +15,7 @@
 use Contao\CoreBundle\Tests\Fixtures\Database\DoctrineArrayStatement;
 use Contao\Database\Result;
 use PHPUnit\Framework\Error\Notice;
+use PHPUnit\Framework\Error\Warning;
 use PHPUnit\Framework\TestCase;
 
 class ResultTest extends TestCase
@@ -52,7 +53,7 @@ public function testEmptyResult(): void
             }
         }
 
-        $this->expectException(Notice::class);
+        $this->expectException(PHP_MAJOR_VERSION < 8 ? Notice::class : Warning::class);
         $resultStatement->fetchField();
     }
 
@@ -95,7 +96,7 @@ public function testSingleRow(): void
             $this->assertSame('value1', $result->fetchField(0));
         }
 
-        $this->expectException(Notice::class);
+        $this->expectException(PHP_MAJOR_VERSION < 8 ? Notice::class : Warning::class);
         $result->fetchField(1);
     }
 
@@ -143,7 +144,7 @@ public function testMultipleRows(): void
             $this->assertSame('value2', $result->fetchField(0));
         }
 
-        $this->expectException(Notice::class);
+        $this->expectException(PHP_MAJOR_VERSION < 8 ? Notice::class : Warning::class);
         $result->fetchField(1);
     }