Compatibility fixes for PHP 8.1 (#19143)

* Update .travis.yml

* fix php 8.1 deprecation notices

* Revert "run report tests on any PHP version (#18666)"

This reverts commit ec58ab4606cbc6c7f7c3a7aa7f1e9cc5a88e5dfb.

* apply PSR12 code formatting

* fix deprecation notice

* try to fix test

* fix frontcontroller test

* Clearing output buffers with enabled output compression makes problems on some PHP versions

* Set the mysqli error reporting to none, to prevent possible problems on PHP 8.1

5 files changed, 29 insertions, 4 deletions

diff --git a/core/Db/Adapter/Mysqli.php b/core/Db/Adapter/Mysqli.php
index a46236c570..928e634294 100644
--- a/core/Db/Adapter/Mysqli.php
+++ b/core/Db/Adapter/Mysqli.php
@@ -82,6 +82,11 @@ class Mysqli extends Zend_Db_Adapter_Mysqli implements AdapterInterface
             return;
         }
 
+        // The default error reporting of mysqli changed in PHP 8.1. To circumvent problems in our error handling we set
+        // the erroring reporting to the default that was used prior PHP 8.1
+        // See https://php.watch/versions/8.1/mysqli-error-mode for more details
+        mysqli_report(MYSQLI_REPORT_OFF);
+
         parent::_connect();
 
         $this->_connection->query('SET sql_mode = "' . Db::SQL_MODE . '"');
diff --git a/core/ProxyHttp.php b/core/ProxyHttp.php
index f8a99dd34f..3f3eb5fec2 100644
--- a/core/ProxyHttp.php
+++ b/core/ProxyHttp.php
@@ -125,7 +125,7 @@ class ProxyHttp
 
         $phpOutputCompressionEnabled = self::isPhpOutputCompressed();
         if (isset($_SERVER['HTTP_ACCEPT_ENCODING']) && !$phpOutputCompressionEnabled) {
-            list($encoding, $extension) = self::getCompressionEncodingAcceptedByClient();
+            [$encoding, $extension] = self::getCompressionEncodingAcceptedByClient();
             $filegz = $compressedFileLocation . $extension;
 
             if (self::canCompressInPhp()) {
@@ -174,10 +174,25 @@ class ProxyHttp
         // it would break the gzipped response since it would have mixed regular notice/string plus gzipped content
         // and would not be able to decode the response
         $levels = ob_get_level();
-        for ( $i = 0; $i < $levels; $i++ ) {
+        for ($i = 0; $i < $levels; $i++) {
             ob_end_clean();
         }
 
+        // clearing all output buffers combined with output compressions had bugs on certain PHP versions
+        // manually removing the Content-Encoding header fixes this
+        // See https://github.com/php/php-src/issues/8218
+        if (
+            $phpOutputCompressionEnabled
+            && (
+                version_compare(PHP_VERSION, '8.0.17', '=')
+                || version_compare(PHP_VERSION, '8.0.18', '=')
+                || version_compare(PHP_VERSION, '8.1.4', '=')
+                || version_compare(PHP_VERSION, '8.1.5', '=')
+            )
+        ) {
+            header_remove("Content-Encoding");
+        }
+
         if (!_readfile($file, $byteStart, $byteEnd)) {
             Common::sendResponseCode(500);
         }
diff --git a/core/ReportRenderer/Pdf.php b/core/ReportRenderer/Pdf.php
index 2ec74f4739..84161a2243 100644
--- a/core/ReportRenderer/Pdf.php
+++ b/core/ReportRenderer/Pdf.php
@@ -169,7 +169,7 @@ class Pdf extends ReportRenderer
 
     public function getRenderedReport()
     {
-        return $this->TCPDF->Output(null, 'S');
+        return $this->TCPDF->Output('', 'S');
     }
 
     public function renderFrontPage($reportTitle, $prettyDate, $description, $reportMetadata, $segment)
diff --git a/core/Site.php b/core/Site.php
index 0b47476adb..1efda88bf8 100644
--- a/core/Site.php
+++ b/core/Site.php
@@ -438,7 +438,7 @@ class Site
         }
         $validIds = array();
         foreach ($ids as $id) {
-            $id = trim($id);
+            $id = is_string($id) ? trim($id) : $id;
             if (!empty($id) && is_numeric($id) && $id > 0) {
                 $validIds[] = $id;
             }
diff --git a/core/Tracker/Db/Mysqli.php b/core/Tracker/Db/Mysqli.php
index 351c1534b8..ceaf12488a 100644
--- a/core/Tracker/Db/Mysqli.php
+++ b/core/Tracker/Db/Mysqli.php
@@ -105,6 +105,11 @@ class Mysqli extends Db
             $timer = $this->initProfiler();
         }
 
+        // The default error reporting of mysqli changed in PHP 8.1. To circumvent problems in our error handling we set
+        // the erroring reporting to the default that was used prior PHP 8.1
+        // See https://php.watch/versions/8.1/mysqli-error-mode for more details
+        mysqli_report(MYSQLI_REPORT_OFF);
+
         $this->connection = mysqli_init();