Use contents of static analysis sourcecode files to generate cache version identifier

Author: sebastianbergmann

src/StaticAnalysis/CachingFileAnalyser.php

@@ -9,19 +9,25 @@
  */
 namespace SebastianBergmann\CodeCoverage\StaticAnalysis;
 
+use function assert;
 use function crc32;
 use function file_get_contents;
 use function file_put_contents;
 use function is_file;
 use function serialize;
+use GlobIterator;
 use SebastianBergmann\CodeCoverage\Util\Filesystem;
+use SplFileInfo;
 
 /**
  * @internal This class is not covered by the backward compatibility promise for phpunit/php-code-coverage
  */
 final class CachingFileAnalyser implements FileAnalyser
 {
-    private const CACHE_FORMAT_VERSION = 2;
+    /**
+     * @var ?string
+     */
+    private static $cacheVersion;
 
     /**
      * @var FileAnalyser
@@ -44,6 +50,10 @@ public function __construct(string $directory, FileAnalyser $analyser)
 
         $this->analyser  = $analyser;
         $this->directory = $directory;
+
+        if (self::$cacheVersion === null) {
+            $this->calculateCacheVersion();
+        }
     }
 
     public function classesIn(string $filename): array
@@ -155,6 +165,19 @@ private function write(string $filename, $data): void
 
     private function cacheFile(string $filename): string
     {
-        return $this->directory . DIRECTORY_SEPARATOR . hash('sha256', $filename . crc32(file_get_contents($filename)) . self::CACHE_FORMAT_VERSION);
+        return $this->directory . DIRECTORY_SEPARATOR . hash('sha256', $filename . crc32(file_get_contents($filename)) . self::$cacheVersion);
+    }
+
+    private function calculateCacheVersion(): void
+    {
+        $buffer = '';
+
+        foreach (new GlobIterator(__DIR__ . '/*.php') as $file) {
+            assert($file instanceof SplFileInfo);
+
+            $buffer .= file_get_contents($file->getPathname());
+        }
+
+        self::$cacheVersion = (string) crc32($buffer);
     }
 }