TempFSFile: Use a WeakMap for reference tracking if available

Use a WeakMap to track references to TempFSFile instances if available
to avoid deprecation warnings for dynamic property creation on PHP 8.2.
Use an anonymous class rather than an stdClass to test the behavior in
TempFSFileTestTrait to verify that bind() does not trigger dynamic
property creation on PHP 8.2.

Also add a Phan stub for WeakMap for PHP 7.4.

Bug: T324894
Change-Id: Ic413c115e9ed1c750e175152094f3309628e777a

.phan/config.php

@@ -30,6 +30,7 @@
  class_exists( Socket::class ) ? [] : [ '.phan/stubs/Socket.php' ],
  class_exists( ReturnTypeWillChange::class ) ? [] : [ '.phan/stubs/ReturnTypeWillChange.php' ],
  class_exists( AllowDynamicProperties::class ) ? [] : [ '.phan/stubs/AllowDynamicProperties.php' ],
+ class_exists( WeakMap::class ) ? [] : [ '.phan/stubs/WeakMap.php' ],
  [
  // This makes constants and globals known to Phan before processing all other files.
  // You can check the parser order with --dump-parsed-file-list

.phan/stubs/WeakMap.php

@@ -0,0 +1,24 @@
+<?php
+
+// Phan stub for PHP 8.0's WeakMap class
+
+ final class WeakMap implements ArrayAccess, Countable, IteratorAggregate {
+
+ public function count(): int {
+ }
+
+ public function getIterator(): Iterator {
+ }
+
+ public function offsetExists( object $object ): bool {
+ }
+
+ public function offsetGet( object $object ): mixed {
+ }
+
+ public function offsetSet( object $object, mixed $value ): void {
+ }
+
+ public function offsetUnset( object $object ): void {
+ }
+ }

includes/libs/filebackend/fsfile/TempFSFile.php

@@ -38,6 +38,14 @@ class TempFSFile extends FSFile {
  /** @var array Map of (path => 1) for paths to delete on shutdown */
  protected static $pathsCollect = null;
 
+ /**
+ * Map objects referencing this temporary file to this instance.
+ * This is used to delay garbage collecting (and thereby removing) this temporary file
+ * until all references to it have been destroyed.
+ * @var WeakMap|null
+ */
+ private $references;
+
  /**
  * Do not call directly. Use TempFSFileFactory
  *
@@ -52,6 +60,11 @@ public function __construct( $path ) {
  register_shutdown_function( [ __CLASS__, 'purgeAllOnShutdown' ] );
  // @codeCoverageIgnoreEnd
  }
+
+ // Use a WeakMap on PHP >= 8.0 for reference tracking to avoid dynamic property creation (T324894)
+ if ( class_exists( WeakMap::class ) ) {
+ $this->references = new WeakMap();
+ }
  }
 
  /**
@@ -130,11 +143,17 @@ public function purge() {
  */
  public function bind( $object ) {
  if ( is_object( $object ) ) {
- if ( !isset( $object->tempFSFileReferences ) ) {
- // Init first since $object might use __get() and return only a copy variable
- $object->tempFSFileReferences = [];
+ // Use a WeakMap on PHP >= 8.0 to avoid dynamic property creation (T324894)
+ if ( $this->references !== null ) {
+ $this->references[$object] = $this;
+ } else {
+ // PHP 7.4
+ if ( !isset( $object->tempFSFileReferences ) ) {
+ // Init first since $object might use __get() and return only a copy variable
+ $object->tempFSFileReferences = [];
+ }
+ $object->tempFSFileReferences[] = $this;
  }
- $object->tempFSFileReferences[] = $this;
  }
 
  return $this;

tests/phpunit/unit/includes/libs/filebackend/fsfile/TempFSFileTestTrait.php

@@ -27,7 +27,8 @@ public function testBind() {
  $file = $this->newFile();
  $path = $file->getPath();
  $this->assertTrue( is_file( $path ) );
- $obj = (object)[];
+ $obj = new class {
+ };
  $file->bind( $obj );
  unset( $file );
  $this->assertTrue( is_file( $path ) );