Get rid of warnings on PHP 8.1

This is mostly about adding return types to methods that implement PHP
interfaces, and not passing null to core functions that want a string.
After this patch, and an update to return types in RemexHtml,
tests/phpunit/integration/ has no more errors than in PHP 8.0.

Bug: T289879
Bug: T289926
Change-Id: Ia424f5cc897070f4188ae126b5bf6a1f552db0e1

1 files changed, 5 insertions, 3 deletions

diff --git a/includes/libs/iterators/IteratorDecorator.php b/includes/libs/iterators/IteratorDecorator.php
index 00eca9674e7e..28dfdbd2a5f3 100644
--- a/includes/libs/iterators/IteratorDecorator.php
+++ b/includes/libs/iterators/IteratorDecorator.php
@@ -38,6 +38,7 @@ abstract class IteratorDecorator implements Iterator {
 	 * @inheritDoc
 	 * @stable to override
 	 */
+	#[\ReturnTypeWillChange]
 	public function current() {
 		return $this->iterator->current();
 	}
@@ -46,6 +47,7 @@ abstract class IteratorDecorator implements Iterator {
 	 * @inheritDoc
 	 * @stable to override
 	 */
+	#[\ReturnTypeWillChange]
 	public function key() {
 		return $this->iterator->key();
 	}
@@ -54,7 +56,7 @@ abstract class IteratorDecorator implements Iterator {
 	 * @inheritDoc
 	 * @stable to override
 	 */
-	public function next() {
+	public function next(): void {
 		$this->iterator->next();
 	}
 
@@ -62,7 +64,7 @@ abstract class IteratorDecorator implements Iterator {
 	 * @inheritDoc
 	 * @stable to override
 	 */
-	public function rewind() {
+	public function rewind(): void {
 		$this->iterator->rewind();
 	}
 
@@ -70,7 +72,7 @@ abstract class IteratorDecorator implements Iterator {
 	 * @inheritDoc
 	 * @stable to override
 	 */
-	public function valid() {
+	public function valid(): bool {
 		return $this->iterator->valid();
 	}
 }