Prevent autoloader or plugin exit status codes of zero from incorrectly resulting in a zero status from Psalm

src/Psalm/Internal/Cli/Psalm.php

@@ -67,6 +67,7 @@
 use function preg_match;
 use function preg_replace;
 use function realpath;
+use function register_shutdown_function;
 use function setlocale;
 use function str_repeat;
 use function str_replace;
@@ -164,6 +165,8 @@ final class Psalm
         'error-level:',
     ];
 
+    private static ?bool $exitDetectionEnabled = null;
+
     /**
      * @param array<int,string> $argv
      * @psalm-suppress ComplexMethod Maybe some of the option handling could be moved to its own function...
@@ -375,10 +378,15 @@ public static function run(array $argv): void
             $config->addPluginPath($plugin_path);
         }
 
-        if ($paths_to_check === null) {
-            $project_analyzer->check($current_dir, $is_diff);
-        } elseif ($paths_to_check) {
-            $project_analyzer->checkPaths($paths_to_check);
+        self::enableExitDetection();
+        try {
+            if ($paths_to_check === null) {
+                $project_analyzer->check($current_dir, $is_diff);
+            } elseif ($paths_to_check) {
+                $project_analyzer->checkPaths($paths_to_check);
+            }
+        } finally {
+            self::disableExitDetection();
         }
 
         if ($find_references_to) {
@@ -408,6 +416,54 @@ public static function run(array $argv): void
         }
     }
 
+    private static function enableExitDetection(): void
+    {
+        if (self::$exitDetectionEnabled === null) {
+            register_shutdown_function(function (): void {
+                if (!self::$exitDetectionEnabled) {
+                    return;
+                }
+
+                $config = Config::getInstance();
+                if (empty($config->getPredefinedConstants())) {
+                    $message = PHP_EOL . self::getAutoloaderExitMessage($config->autoloader);
+                } else {
+                    $message = self::getUnexpectedExitMessage();
+                }
+
+                fwrite(STDERR, $message . PHP_EOL);
+
+                /**
+                 * A die() or exit() call was made at an unexpected time
+                 * (e.g., within an autoloader or plugin).
+                 * That call might have been made with a zero status (we have no way of knowing for sure).
+                 * We exit with a non-zero status instead to ensure that any calling scripts do not misinterpret
+                 * the zero exit status as Psalm succeeding when it did not.
+                 * A code of 2 is required per PsalmRunnerTrait::runPsalm().
+                 */
+                die(2);
+            });
+        }
+
+        self::$exitDetectionEnabled = true;
+    }
+
+    public static function disableExitDetection(): void
+    {
+        self::$exitDetectionEnabled = false;
+    }
+
+    public static function getAutoloaderExitMessage(?string $autoloaderPath): string
+    {
+        return "Problem running $autoloaderPath:" . PHP_EOL
+        . "  The autoloader failed with the above output and a die() or exit() call.";
+    }
+
+    public static function getUnexpectedExitMessage(): string
+    {
+        return 'Psalm ended unexpectedly.  This could be caused by a die() or exit() in a plugin.';
+    }
+
     private static function initOutputFormat(array $options): string
     {
         return isset($options['output-format']) && is_string($options['output-format'])

src/Psalm/Internal/Fork/Pool.php

@@ -5,6 +5,7 @@
 use Closure;
 use Exception;
 use Psalm\Config;
+use Psalm\Internal\Cli\Psalm;
 use Throwable;
 
 use function array_fill_keys;
@@ -269,6 +270,8 @@ public function __construct(
 
         fclose($write_stream);
 
+        Psalm::disableExitDetection();
+
         // Children exit after completing their work
         exit(self::EXIT_SUCCESS);
     }

tests/EndToEnd/ExitStatusTest.php

@@ -0,0 +1,89 @@
+<?php
+
+namespace Psalm\Tests\EndToEnd;
+
+use PHPUnit\Framework\TestCase;
+use Psalm\Internal\Cli\Psalm;
+
+use function array_pop;
+use function array_shift;
+use function explode;
+use function realpath;
+use function strlen;
+use function substr;
+use function trim;
+
+class ExitStatusTest extends TestCase
+{
+    use PsalmRunnerTrait;
+
+    public function testAutoloaderExitStatus(): void
+    {
+        $this->assert(
+            'Example output from failing autoloader',
+            Psalm::getAutoloaderExitMessage(realpath($this->getFixturePath(). 'autoloader.php')),
+        );
+    }
+
+    public function testPluginHookExitStatus(): void
+    {
+        $this->assert(
+            'Example output from failing hook',
+            Psalm::getUnexpectedExitMessage(),
+        );
+    }
+
+    private function assert(string $expectedSTDOUT, string $expectedSTDERR): void
+    {
+        $output = $this->runPsalm(['--no-cache'], $this->getFixturePath(), true);
+
+        $this->assertSame($this->getLines($expectedSTDOUT), $this->getLines($output['STDOUT']));
+        $this->assertSame($this->getLines($expectedSTDERR), $this->handleSTDERR($this->getLines($output['STDERR'])));
+        $this->assertSame(2, $output['CODE']);
+    }
+
+    private function getFixture(): string
+    {
+        return substr($this->getName(), strlen('test'));
+    }
+
+    private function getFixturePath(): string
+    {
+        $fixture = $this->getFixture();
+        return __DIR__ . "/../fixtures/$fixture/";
+    }
+
+    /**
+     * @return array<string>
+     */
+    private function getLines(string $output): array
+    {
+        $lines = explode("\n", $output);
+
+        $newLines = [];
+        foreach ($lines as $line) {
+            // Trim any carriages returns on Windows
+            $newLines[] = trim($line);
+        }
+
+        return $newLines;
+    }
+
+    /**
+     * @param array<string> $lines
+     */
+    private function handleSTDERR(array $lines): array
+    {
+        $this->assertStringStartsWith('Target PHP version: ', array_shift($lines));
+        $this->assertStringStartsWith('Scanning files...', array_shift($lines));
+
+        if ($lines[0] === 'Analyzing files...') {
+            array_shift($lines);
+        }
+
+        $this->assertSame('', array_shift($lines));
+        $this->assertSame('', array_pop($lines));
+
+        return $lines;
+    }
+}

tests/fixtures/AutoloaderExitStatus/autoloader.php

@@ -0,0 +1,4 @@
+<?php
+
+// The following causes a zero exit status, which we explicitly want to ensure does NOT result in a zero exit status from Psalm itself.
+die('Example output from failing autoloader');

tests/fixtures/AutoloaderExitStatus/file.php

@@ -0,0 +1 @@
+<?php

tests/fixtures/AutoloaderExitStatus/psalm.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<psalm
+    autoloader="autoloader.php"
+    resolveFromConfigFile="true"
+    findUnusedCode="true"
+    findUnusedBaselineEntry="true"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+>
+    <projectFiles>
+        <file name="file.php" />
+    </projectFiles>
+</psalm>

tests/fixtures/PluginHookExitStatus/ExitStatusPlugin.php

@@ -0,0 +1,12 @@
+<?php
+
+use Psalm\Plugin\EventHandler\AfterFileAnalysisInterface;
+use Psalm\Plugin\EventHandler\Event\AfterFileAnalysisEvent;
+
+class ExitStatusPlugin implements AfterFileAnalysisInterface
+{
+    public static function afterAnalyzeFile(AfterFileAnalysisEvent $event): void {
+        // The following causes a zero exit status, which we explicitly want to ensure does NOT result in a zero exit status from Psalm itself.
+        die('Example output from failing hook');
+    }
+}

tests/fixtures/PluginHookExitStatus/psalm.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0"?>
+<psalm
+    resolveFromConfigFile="true"
+    findUnusedCode="true"
+    findUnusedBaselineEntry="true"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+>
+    <projectFiles>
+        <file name="file.php" />
+    </projectFiles>
+    <plugins>
+        <plugin filename="ExitStatusPlugin.php" />
+    </plugins>
+</psalm>