Closes #5860

Author: sebastianbergmann

ChangeLog-12.5.md

@@ -2,6 +2,12 @@
 
 All notable changes of the PHPUnit 12.5 release series are documented in this file using the [Keep a CHANGELOG](https://keepachangelog.com/) principles.
 
+## [12.5.21] - 2026-MM-DD
+
+### Fixed
+
+* [#5860](https://github.com/sebastianbergmann/phpunit/issues/5860): PHP CLI `-d` settings are not forwarded to child processes for process isolation
+
 ## [12.5.20] - 2026-04-15
 
 ### Fixed
@@ -187,6 +193,7 @@ All notable changes of the PHPUnit 12.5 release series are documented in this fi
 * [#6380](https://github.com/sebastianbergmann/phpunit/pull/6380): Allow `Throwable` in `expectExceptionObject()`
 * A PHPUnit notice is now emitted for test methods that create a mock object but do not configure an expectation for it
 
+[12.5.21]: https://github.com/sebastianbergmann/phpunit/compare/12.5.20...12.5
 [12.5.20]: https://github.com/sebastianbergmann/phpunit/compare/12.5.19...12.5.20
 [12.5.19]: https://github.com/sebastianbergmann/phpunit/compare/12.5.18...12.5.19
 [12.5.18]: https://github.com/sebastianbergmann/phpunit/compare/12.5.17...12.5.18

src/Util/PHP/DefaultJobRunner.php

@@ -260,6 +260,8 @@ private function buildCommand(Job $job, ?string $file): array
             }
         }
 
+        $phpSettings = array_merge($phpSettings, $this->cliIniOverrides($phpSettings));
+
         $command = array_merge($command, $this->settingsToParameters(array_values($phpSettings)));
 
         if (PHP_SAPI === 'phpdbg') {
@@ -288,6 +290,36 @@ private function buildCommand(Job $job, ?string $file): array
         return $command;
     }
 
+    /**
+     * Detects INI settings that cannot be set via ini_set() (PHP_INI_SYSTEM
+     * and PHP_INI_PERDIR) and whose current value differs from the value
+     * configured in INI files.
+     *
+     * These settings must be forwarded as -d flags to child processes
+     * because the @ini_set() calls in GlobalState::getIniSettingsAsString()
+     * cannot change them at runtime.
+     *
+     * @param array<array-key, string> $alreadySet
+     *
+     * @return array<string, string>
+     */
+    private function cliIniOverrides(array $alreadySet): array
+    {
+        $overrides = (new Runtime)->getSettingsNotChangeableAtRuntime();
+
+        foreach ($overrides as $key => $value) {
+            foreach ($alreadySet as $existing) {
+                if (str_starts_with($existing, $key . '=')) {
+                    unset($overrides[$key]);
+
+                    break;
+                }
+            }
+        }
+
+        return $overrides;
+    }
+
     /**
      * @param list<string> $settings
      *

tests/end-to-end/generic/_files/AutoPrependFileTest.php

@@ -0,0 +1,23 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture;
+
+use function defined;
+use PHPUnit\Framework\Attributes\RunInSeparateProcess;
+use PHPUnit\Framework\TestCase;
+
+final class AutoPrependFileTest extends TestCase
+{
+    #[RunInSeparateProcess]
+    public function testAutoPrependFileIsLoadedInChildProcess(): void
+    {
+        $this->assertTrue(defined('AUTO_PREPEND_FILE_LOADED'));
+    }
+}

tests/end-to-end/generic/_files/auto_prepend_file.php

@@ -0,0 +1,10 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+\define('AUTO_PREPEND_FILE_LOADED', true);

tests/end-to-end/generic/php-cli-d-forwarded-to-child-process.phpt

@@ -0,0 +1,43 @@
+--TEST--
+PHP CLI -d settings are forwarded to child processes when using process isolation
+--FILE--
+<?php declare(strict_types=1);
+
+$process = proc_open(
+    [
+        PHP_BINARY,
+        '-d',
+        'auto_prepend_file=' . __DIR__ . '/_files/auto_prepend_file.php',
+        __DIR__ . '/../../../phpunit',
+        '--do-not-cache-result',
+        '--no-configuration',
+        __DIR__ . '/_files/AutoPrependFileTest.php',
+    ],
+    [
+        1 => ['pipe', 'w'],
+        2 => ['pipe', 'w'],
+    ],
+    $pipes,
+);
+
+print stream_get_contents($pipes[1]);
+fclose($pipes[1]);
+
+$stderr = stream_get_contents($pipes[2]);
+fclose($pipes[2]);
+
+proc_close($process);
+
+if ($stderr !== '') {
+    print $stderr;
+}
+--EXPECTF--
+PHPUnit %s by Sebastian Bergmann and contributors.
+
+Runtime: %s
+
+.                                                                   1 / 1 (100%)
+
+Time: %s, Memory: %s
+
+OK (1 test, 1 assertion)