diff --git a/Zend/tests/ns_054.phpt b/Zend/tests/ns_054.phpt
index 9b8defc9ac3f4..845d02a396552 100644
--- a/Zend/tests/ns_054.phpt
+++ b/Zend/tests/ns_054.phpt
@@ -5,18 +5,18 @@
 namespace test\ns1;
 
 class Foo implements \SplObserver {
-    function update(\SplSubject $x) {
+    function update(\SplSubject $x): void {
         echo "ok\n";
     }
 }
 
 class Bar implements \SplSubject {
-    function attach(\SplObserver $x) {
+    function attach(\SplObserver $x): void {
         echo "ok\n";
     }
-    function notify() {
+    function notify(): void {
     }
-    function detach(\SplObserver $x) {
+    function detach(\SplObserver $x): void {
     }
 }
 $foo = new Foo();
diff --git a/Zend/tests/ns_056.phpt b/Zend/tests/ns_056.phpt
index cc61c7f8f1359..ee8ddd6263e35 100644
--- a/Zend/tests/ns_056.phpt
+++ b/Zend/tests/ns_056.phpt
@@ -6,18 +6,18 @@ namespace test\ns1;
 use \SplObserver;
 
 class Foo implements SplObserver {
-    function update(\SplSubject $x) {
+    function update(\SplSubject $x): void {
         echo "ok\n";
     }
 }
 
 class Bar implements \SplSubject {
-    function attach(SplObserver $x) {
+    function attach(SplObserver $x): void {
         echo "ok\n";
     }
-    function notify() {
+    function notify(): void {
     }
-    function detach(SplObserver $x) {
+    function detach(SplObserver $x): void {
     }
 }
 $foo = new Foo();
diff --git a/ext/spl/spl_dllist.stub.php b/ext/spl/spl_dllist.stub.php
index 36b945afb78c4..f8d3c98514181 100644
--- a/ext/spl/spl_dllist.stub.php
+++ b/ext/spl/spl_dllist.stub.php
@@ -4,110 +4,110 @@
 
 class SplDoublyLinkedList implements Iterator, Countable, ArrayAccess, Serializable
 {
-    /** @return void */
-    public function add(int $index, mixed $value) {}
+    /** @tentative-return-type */
+    public function add(int $index, mixed $value): void {}
 
-    /** @return mixed */
-    public function pop() {}
+    /** @tentative-return-type */
+    public function pop(): mixed {}
 
-    /** @return mixed */
-    public function shift() {}
+    /** @tentative-return-type */
+    public function shift(): mixed {}
 
-    /** @return void */
-    public function push(mixed $value) {}
+    /** @tentative-return-type */
+    public function push(mixed $value): void {}
 
-    /** @return void */
-    public function unshift(mixed $value) {}
+    /** @tentative-return-type */
+    public function unshift(mixed $value): void {}
 
-    /** @return mixed */
-    public function top() {}
+    /** @tentative-return-type */
+    public function top(): mixed {}
 
-    /** @return mixed */
-    public function bottom() {}
+    /** @tentative-return-type */
+    public function bottom(): mixed {}
 
-    /** @return array */
-    public function __debugInfo() {}
+    /** @tentative-return-type */
+    public function __debugInfo(): array {}
 
-    /** @return int */
-    public function count() {}
+    /** @tentative-return-type */
+    public function count(): int {}
 
-    /** @return bool */
-    public function isEmpty() {}
+    /** @tentative-return-type */
+    public function isEmpty(): bool {}
 
-    /** @return int */
-    public function setIteratorMode(int $mode) {}
+    /** @tentative-return-type */
+    public function setIteratorMode(int $mode): int {}
 
-    /** @return int */
-    public function getIteratorMode() {}
+    /** @tentative-return-type */
+    public function getIteratorMode(): int {}
 
     /**
      * @param int $index
-     * @return bool
+     * @tentative-return-type
      */
-    public function offsetExists($index) {}
+    public function offsetExists($index): bool {}
 
     /**
      * @param int $index
-     * @return mixed
+     * @tentative-return-type
      */
-    public function offsetGet($index) {}
+    public function offsetGet($index): mixed {}
 
     /**
      * @param int|null $index
-     * @return void
+     * @tentative-return-type
      */
-    public function offsetSet($index, mixed $value) {}
+    public function offsetSet($index, mixed $value): void {}
 
     /**
      * @param int $index
-     * @return void
+     * @tentative-return-type
      */
-    public function offsetUnset($index) {}
+    public function offsetUnset($index): void {}
 
-    /** @return void */
-    public function rewind() {}
+    /** @tentative-return-type */
+    public function rewind(): void {}
 
-    /** @return mixed */
-    public function current() {}
+    /** @tentative-return-type */
+    public function current(): mixed {}
 
-    /** @return int */
-    public function key() {}
+    /** @tentative-return-type */
+    public function key(): int {}
 
-    /** @return void */
-    public function prev() {}
+    /** @tentative-return-type */
+    public function prev(): void {}
 
-    /** @return void */
-    public function next() {}
+    /** @tentative-return-type */
+    public function next(): void {}
 
-    /** @return bool */
-    public function valid() {}
+    /** @tentative-return-type */
+    public function valid(): bool {}
 
-    /** @return void */
-    public function unserialize(string $data) {}
+    /** @tentative-return-type */
+    public function unserialize(string $data): void {}
 
-    /** @return string */
-    public function serialize() {}
+    /** @tentative-return-type */
+    public function serialize(): string {}
 
-    /** @return array */
-    public function __serialize() {}
+    /** @tentative-return-type */
+    public function __serialize(): array {}
 
-    /** @return void */
-    public function __unserialize(array $data) {}
+    /** @tentative-return-type */
+    public function __unserialize(array $data): void {}
 }
 
 class SplQueue extends SplDoublyLinkedList
 {
     /**
-     * @return void
+     * @tentative-return-type
      * @implementation-alias SplDoublyLinkedList::push
      */
-    public function enqueue(mixed $value) {}
+    public function enqueue(mixed $value): void {}
 
     /**
-     * @return mixed
+     * @tentative-return-type
      * @implementation-alias SplDoublyLinkedList::shift
      */
-    public function dequeue() {}
+    public function dequeue(): mixed {}
 }
 
 class SplStack extends SplDoublyLinkedList
diff --git a/ext/spl/spl_dllist_arginfo.h b/ext/spl/spl_dllist_arginfo.h
index 5162ff2957209..7238bcde3412e 100644
--- a/ext/spl/spl_dllist_arginfo.h
+++ b/ext/spl/spl_dllist_arginfo.h
@@ -1,17 +1,17 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: d0c98e1628895a81ac0b4abe62dede9ed2c7f55e */
+ * Stub hash: 4631669bb268bb2c9e005fa7ee385245604c1d71 */
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplDoublyLinkedList_add, 0, 0, 2)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_add, 0, 2, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, index, IS_LONG, 0)
 	ZEND_ARG_TYPE_INFO(0, value, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplDoublyLinkedList_pop, 0, 0, 0)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_pop, 0, 0, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplDoublyLinkedList_shift arginfo_class_SplDoublyLinkedList_pop
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplDoublyLinkedList_push, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_push, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, value, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
@@ -21,52 +21,61 @@ ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplDoublyLinkedList_bottom arginfo_class_SplDoublyLinkedList_pop
 
-#define arginfo_class_SplDoublyLinkedList___debugInfo arginfo_class_SplDoublyLinkedList_pop
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList___debugInfo, 0, 0, IS_ARRAY, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplDoublyLinkedList_count arginfo_class_SplDoublyLinkedList_pop
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_count, 0, 0, IS_LONG, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplDoublyLinkedList_isEmpty arginfo_class_SplDoublyLinkedList_pop
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_isEmpty, 0, 0, _IS_BOOL, 0)
+ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplDoublyLinkedList_setIteratorMode, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_setIteratorMode, 0, 1, IS_LONG, 0)
 	ZEND_ARG_TYPE_INFO(0, mode, IS_LONG, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplDoublyLinkedList_getIteratorMode arginfo_class_SplDoublyLinkedList_pop
+#define arginfo_class_SplDoublyLinkedList_getIteratorMode arginfo_class_SplDoublyLinkedList_count
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplDoublyLinkedList_offsetExists, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_offsetExists, 0, 1, _IS_BOOL, 0)
 	ZEND_ARG_INFO(0, index)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplDoublyLinkedList_offsetGet arginfo_class_SplDoublyLinkedList_offsetExists
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_offsetGet, 0, 1, IS_MIXED, 0)
+	ZEND_ARG_INFO(0, index)
+ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplDoublyLinkedList_offsetSet, 0, 0, 2)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_offsetSet, 0, 2, IS_VOID, 0)
 	ZEND_ARG_INFO(0, index)
 	ZEND_ARG_TYPE_INFO(0, value, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplDoublyLinkedList_offsetUnset arginfo_class_SplDoublyLinkedList_offsetExists
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_offsetUnset, 0, 1, IS_VOID, 0)
+	ZEND_ARG_INFO(0, index)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplDoublyLinkedList_rewind arginfo_class_SplDoublyLinkedList_pop
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_rewind, 0, 0, IS_VOID, 0)
+ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplDoublyLinkedList_current arginfo_class_SplDoublyLinkedList_pop
 
-#define arginfo_class_SplDoublyLinkedList_key arginfo_class_SplDoublyLinkedList_pop
+#define arginfo_class_SplDoublyLinkedList_key arginfo_class_SplDoublyLinkedList_count
 
-#define arginfo_class_SplDoublyLinkedList_prev arginfo_class_SplDoublyLinkedList_pop
+#define arginfo_class_SplDoublyLinkedList_prev arginfo_class_SplDoublyLinkedList_rewind
 
-#define arginfo_class_SplDoublyLinkedList_next arginfo_class_SplDoublyLinkedList_pop
+#define arginfo_class_SplDoublyLinkedList_next arginfo_class_SplDoublyLinkedList_rewind
 
-#define arginfo_class_SplDoublyLinkedList_valid arginfo_class_SplDoublyLinkedList_pop
+#define arginfo_class_SplDoublyLinkedList_valid arginfo_class_SplDoublyLinkedList_isEmpty
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplDoublyLinkedList_unserialize, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_unserialize, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, data, IS_STRING, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplDoublyLinkedList_serialize arginfo_class_SplDoublyLinkedList_pop
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList_serialize, 0, 0, IS_STRING, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplDoublyLinkedList___serialize arginfo_class_SplDoublyLinkedList_pop
+#define arginfo_class_SplDoublyLinkedList___serialize arginfo_class_SplDoublyLinkedList___debugInfo
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplDoublyLinkedList___unserialize, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplDoublyLinkedList___unserialize, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, data, IS_ARRAY, 0)
 ZEND_END_ARG_INFO()
 
diff --git a/ext/spl/spl_fixedarray.stub.php b/ext/spl/spl_fixedarray.stub.php
index 790a1df3e373a..17076434aa86d 100644
--- a/ext/spl/spl_fixedarray.stub.php
+++ b/ext/spl/spl_fixedarray.stub.php
@@ -6,47 +6,47 @@ class SplFixedArray implements IteratorAggregate, ArrayAccess, Countable, JsonSe
 {
     public function __construct(int $size = 0) {}
 
-    /** @return void */
-    public function __wakeup() {}
+    /** @tentative-return-type */
+    public function __wakeup(): void {}
 
-    /** @return int */
-    public function count() {}
+    /** @tentative-return-type */
+    public function count(): int {}
 
-    /** @return array */
-    public function toArray() {}
+    /** @tentative-return-type */
+    public function toArray(): array {}
 
-    /** @return SplFixedArray */
-    public static function fromArray(array $array, bool $preserveKeys = true) {}
+    /** @tentative-return-type */
+    public static function fromArray(array $array, bool $preserveKeys = true): SplFixedArray {}
 
-    /** @return int */
-    public function getSize() {}
+    /** @tentative-return-type */
+    public function getSize(): int {}
 
-    /** @return bool */
-    public function setSize(int $size) {}
+    /** @tentative-return-type */
+    public function setSize(int $size): bool {}
 
     /**
      * @param int $index
-     * @return bool
+     * @tentative-return-type
      */
-    public function offsetExists($index) {}
+    public function offsetExists($index): bool {}
 
     /**
      * @param int $index
-     * @return mixed
+     * @tentative-return-type
      */
-    public function offsetGet($index) {}
+    public function offsetGet($index): mixed {}
 
     /**
      * @param int $index
-     * @return void
+     * @tentative-return-type
      */
-    public function offsetSet($index, mixed $value) {}
+    public function offsetSet($index, mixed $value): void {}
 
     /**
      * @param int $index
-     * @return void
+     * @tentative-return-type
      */
-    public function offsetUnset($index) {}
+    public function offsetUnset($index): void {}
 
     public function getIterator(): Iterator {}
 
diff --git a/ext/spl/spl_fixedarray_arginfo.h b/ext/spl/spl_fixedarray_arginfo.h
index eaec9f1fc33e2..857adb4f5adaf 100644
--- a/ext/spl/spl_fixedarray_arginfo.h
+++ b/ext/spl/spl_fixedarray_arginfo.h
@@ -1,40 +1,46 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 115b2d974b18287654be925c4fdc2236674423eb */
+ * Stub hash: 15368e20d4286f79ecd3d33326ecaf5d2a78855c */
 
 ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplFixedArray___construct, 0, 0, 0)
 	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, size, IS_LONG, 0, "0")
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplFixedArray___wakeup, 0, 0, 0)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplFixedArray___wakeup, 0, 0, IS_VOID, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplFixedArray_count arginfo_class_SplFixedArray___wakeup
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplFixedArray_count, 0, 0, IS_LONG, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplFixedArray_toArray arginfo_class_SplFixedArray___wakeup
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplFixedArray_toArray, 0, 0, IS_ARRAY, 0)
+ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplFixedArray_fromArray, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_OBJ_INFO_EX(arginfo_class_SplFixedArray_fromArray, 0, 1, SplFixedArray, 0)
 	ZEND_ARG_TYPE_INFO(0, array, IS_ARRAY, 0)
 	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, preserveKeys, _IS_BOOL, 0, "true")
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplFixedArray_getSize arginfo_class_SplFixedArray___wakeup
+#define arginfo_class_SplFixedArray_getSize arginfo_class_SplFixedArray_count
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplFixedArray_setSize, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplFixedArray_setSize, 0, 1, _IS_BOOL, 0)
 	ZEND_ARG_TYPE_INFO(0, size, IS_LONG, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplFixedArray_offsetExists, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplFixedArray_offsetExists, 0, 1, _IS_BOOL, 0)
 	ZEND_ARG_INFO(0, index)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplFixedArray_offsetGet arginfo_class_SplFixedArray_offsetExists
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplFixedArray_offsetGet, 0, 1, IS_MIXED, 0)
+	ZEND_ARG_INFO(0, index)
+ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplFixedArray_offsetSet, 0, 0, 2)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplFixedArray_offsetSet, 0, 2, IS_VOID, 0)
 	ZEND_ARG_INFO(0, index)
 	ZEND_ARG_TYPE_INFO(0, value, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplFixedArray_offsetUnset arginfo_class_SplFixedArray_offsetExists
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplFixedArray_offsetUnset, 0, 1, IS_VOID, 0)
+	ZEND_ARG_INFO(0, index)
+ZEND_END_ARG_INFO()
 
 ZEND_BEGIN_ARG_WITH_RETURN_OBJ_INFO_EX(arginfo_class_SplFixedArray_getIterator, 0, 0, Iterator, 0)
 ZEND_END_ARG_INFO()
diff --git a/ext/spl/spl_heap.stub.php b/ext/spl/spl_heap.stub.php
index 2f31ded011b87..dbd5555803182 100644
--- a/ext/spl/spl_heap.stub.php
+++ b/ext/spl/spl_heap.stub.php
@@ -4,132 +4,132 @@
 
 class SplPriorityQueue implements Iterator, Countable
 {
-    /** @return int */
-    public function compare(mixed $priority1, mixed $priority2) {}
+    /** @tentative-return-type */
+    public function compare(mixed $priority1, mixed $priority2): int {}
 
-    /** @return bool */
-    public function insert(mixed $value, mixed $priority) {}
+    /** @tentative-return-type */
+    public function insert(mixed $value, mixed $priority): bool {}
 
-    /** @return int */
-    public function setExtractFlags(int $flags) {}
+    /** @tentative-return-type */
+    public function setExtractFlags(int $flags): int {}
 
-    /** @return mixed */
-    public function top() {}
+    /** @tentative-return-type */
+    public function top(): mixed {}
 
-    /** @return mixed */
-    public function extract() {}
+    /** @tentative-return-type */
+    public function extract(): mixed {}
 
     /**
-     * @return int
+     * @tentative-return-type
      * @implementation-alias SplHeap::count
      */
-    public function count() {}
+    public function count(): int {}
 
     /**
-     * @return bool
+     * @tentative-return-type
      * @implementation-alias SplHeap::isEmpty
      */
-    public function isEmpty() {}
+    public function isEmpty(): bool {}
 
     /**
-     * @return void
+     * @tentative-return-type
      * @implementation-alias SplHeap::rewind
      */
-    public function rewind() {}
+    public function rewind(): void {}
 
-    /** @return mixed */
-    public function current() {}
+    /** @tentative-return-type */
+    public function current(): mixed {}
 
     /**
-     * @return int
+     * @tentative-return-type
      * @implementation-alias SplHeap::key
      */
-    public function key() {}
+    public function key(): int {}
 
     /**
-     * @return void
+     * @tentative-return-type
      * @implementation-alias SplHeap::next
      */
-    public function next() {}
+    public function next(): void {}
 
     /**
-     * @return bool
+     * @tentative-return-type
      * @implementation-alias SplHeap::valid
      */
-    public function valid() {}
+    public function valid(): bool {}
 
     /**
-     * @return bool
+     * @tentative-return-type
      * @implementation-alias SplHeap::recoverFromCorruption
      */
-    public function recoverFromCorruption() {}
+    public function recoverFromCorruption(): bool {}
 
     /**
-     * @return bool
+     * @tentative-return-type
      * @implementation-alias SplHeap::isCorrupted
      */
-    public function isCorrupted() {}
+    public function isCorrupted(): bool {}
 
-    /** @return int */
-    public function getExtractFlags() {}
+    /** @tentative-return-type */
+    public function getExtractFlags(): int {}
 
-    /** @return array */
-    public function __debugInfo() {}
+    /** @tentative-return-type */
+    public function __debugInfo(): array {}
 }
 
 abstract class SplHeap implements Iterator, Countable
 {
-    /** @return mixed */
-    public function extract() {}
+    /** @tentative-return-type */
+    public function extract(): mixed {}
 
-    /** @return bool */
-    public function insert(mixed $value) {}
+    /** @tentative-return-type */
+    public function insert(mixed $value): bool {}
 
-    /** @return mixed */
-    public function top() {}
+    /** @tentative-return-type */
+    public function top(): mixed {}
 
-    /** @return int */
-    public function count() {}
+    /** @tentative-return-type */
+    public function count(): int {}
 
-    /** @return bool */
-    public function isEmpty() {}
+    /** @tentative-return-type */
+    public function isEmpty(): bool {}
 
-    /** @return void */
-    public function rewind() {}
+    /** @tentative-return-type */
+    public function rewind(): void {}
 
-    /** @return mixed */
-    public function current() {}
+    /** @tentative-return-type */
+    public function current(): mixed {}
 
-    /** @return int */
-    public function key() {}
+    /** @tentative-return-type */
+    public function key(): int {}
 
-    /** @return void */
-    public function next() {}
+    /** @tentative-return-type */
+    public function next(): void {}
 
-    /** @return bool */
-    public function valid() {}
+    /** @tentative-return-type */
+    public function valid(): bool {}
 
-    /** @return bool */
-    public function recoverFromCorruption() {}
+    /** @tentative-return-type */
+    public function recoverFromCorruption(): bool {}
 
-    /** @return int */
-    abstract protected function compare(mixed $value1, mixed $value2);
+    /** @tentative-return-type */
+    abstract protected function compare(mixed $value1, mixed $value2): int;
 
-    /** @return bool */
-    public function isCorrupted() {}
+    /** @tentative-return-type */
+    public function isCorrupted(): bool {}
 
-    /** @return array */
-    public function __debugInfo() {}
+    /** @tentative-return-type */
+    public function __debugInfo(): array {}
 }
 
 class SplMinHeap extends SplHeap
 {
-    /** @return int */
-    protected function compare(mixed $value1, mixed $value2) {}
+    /** @tentative-return-type */
+    protected function compare(mixed $value1, mixed $value2): int {}
 }
 
 class SplMaxHeap extends SplHeap
 {
-    /** @return int */
-    protected function compare(mixed $value1, mixed $value2) {}
+    /** @tentative-return-type */
+    protected function compare(mixed $value1, mixed $value2): int {}
 }
diff --git a/ext/spl/spl_heap_arginfo.h b/ext/spl/spl_heap_arginfo.h
index 2afc289a1e564..08ddcf42c8287 100644
--- a/ext/spl/spl_heap_arginfo.h
+++ b/ext/spl/spl_heap_arginfo.h
@@ -1,79 +1,83 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 9a733260823a95ba1ab987154e23d72b6210999d */
+ * Stub hash: 57a43ef3f1f2dca1ef45daea0170985059f15fe6 */
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplPriorityQueue_compare, 0, 0, 2)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplPriorityQueue_compare, 0, 2, IS_LONG, 0)
 	ZEND_ARG_TYPE_INFO(0, priority1, IS_MIXED, 0)
 	ZEND_ARG_TYPE_INFO(0, priority2, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplPriorityQueue_insert, 0, 0, 2)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplPriorityQueue_insert, 0, 2, _IS_BOOL, 0)
 	ZEND_ARG_TYPE_INFO(0, value, IS_MIXED, 0)
 	ZEND_ARG_TYPE_INFO(0, priority, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplPriorityQueue_setExtractFlags, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplPriorityQueue_setExtractFlags, 0, 1, IS_LONG, 0)
 	ZEND_ARG_TYPE_INFO(0, flags, IS_LONG, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplPriorityQueue_top, 0, 0, 0)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplPriorityQueue_top, 0, 0, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplPriorityQueue_extract arginfo_class_SplPriorityQueue_top
 
-#define arginfo_class_SplPriorityQueue_count arginfo_class_SplPriorityQueue_top
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplPriorityQueue_count, 0, 0, IS_LONG, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplPriorityQueue_isEmpty arginfo_class_SplPriorityQueue_top
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplPriorityQueue_isEmpty, 0, 0, _IS_BOOL, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplPriorityQueue_rewind arginfo_class_SplPriorityQueue_top
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplPriorityQueue_rewind, 0, 0, IS_VOID, 0)
+ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplPriorityQueue_current arginfo_class_SplPriorityQueue_top
 
-#define arginfo_class_SplPriorityQueue_key arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplPriorityQueue_key arginfo_class_SplPriorityQueue_count
 
-#define arginfo_class_SplPriorityQueue_next arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplPriorityQueue_next arginfo_class_SplPriorityQueue_rewind
 
-#define arginfo_class_SplPriorityQueue_valid arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplPriorityQueue_valid arginfo_class_SplPriorityQueue_isEmpty
 
-#define arginfo_class_SplPriorityQueue_recoverFromCorruption arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplPriorityQueue_recoverFromCorruption arginfo_class_SplPriorityQueue_isEmpty
 
-#define arginfo_class_SplPriorityQueue_isCorrupted arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplPriorityQueue_isCorrupted arginfo_class_SplPriorityQueue_isEmpty
 
-#define arginfo_class_SplPriorityQueue_getExtractFlags arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplPriorityQueue_getExtractFlags arginfo_class_SplPriorityQueue_count
 
-#define arginfo_class_SplPriorityQueue___debugInfo arginfo_class_SplPriorityQueue_top
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplPriorityQueue___debugInfo, 0, 0, IS_ARRAY, 0)
+ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplHeap_extract arginfo_class_SplPriorityQueue_top
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplHeap_insert, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplHeap_insert, 0, 1, _IS_BOOL, 0)
 	ZEND_ARG_TYPE_INFO(0, value, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplHeap_top arginfo_class_SplPriorityQueue_top
 
-#define arginfo_class_SplHeap_count arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap_count arginfo_class_SplPriorityQueue_count
 
-#define arginfo_class_SplHeap_isEmpty arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap_isEmpty arginfo_class_SplPriorityQueue_isEmpty
 
-#define arginfo_class_SplHeap_rewind arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap_rewind arginfo_class_SplPriorityQueue_rewind
 
 #define arginfo_class_SplHeap_current arginfo_class_SplPriorityQueue_top
 
-#define arginfo_class_SplHeap_key arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap_key arginfo_class_SplPriorityQueue_count
 
-#define arginfo_class_SplHeap_next arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap_next arginfo_class_SplPriorityQueue_rewind
 
-#define arginfo_class_SplHeap_valid arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap_valid arginfo_class_SplPriorityQueue_isEmpty
 
-#define arginfo_class_SplHeap_recoverFromCorruption arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap_recoverFromCorruption arginfo_class_SplPriorityQueue_isEmpty
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplHeap_compare, 0, 0, 2)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplHeap_compare, 0, 2, IS_LONG, 0)
 	ZEND_ARG_TYPE_INFO(0, value1, IS_MIXED, 0)
 	ZEND_ARG_TYPE_INFO(0, value2, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplHeap_isCorrupted arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap_isCorrupted arginfo_class_SplPriorityQueue_isEmpty
 
-#define arginfo_class_SplHeap___debugInfo arginfo_class_SplPriorityQueue_top
+#define arginfo_class_SplHeap___debugInfo arginfo_class_SplPriorityQueue___debugInfo
 
 #define arginfo_class_SplMinHeap_compare arginfo_class_SplHeap_compare
 
diff --git a/ext/spl/spl_observer.stub.php b/ext/spl/spl_observer.stub.php
index fe2aa269d01e6..e5ea360354f4d 100644
--- a/ext/spl/spl_observer.stub.php
+++ b/ext/spl/spl_observer.stub.php
@@ -4,155 +4,155 @@
 
 interface SplObserver
 {
-    /** @return void */
-    public function update(SplSubject $subject);
+    /** @tentative-return-type */
+    public function update(SplSubject $subject): void;
 }
 
 interface SplSubject
 {
-    /** @return void */
-    public function attach(SplObserver $observer);
+    /** @tentative-return-type */
+    public function attach(SplObserver $observer): void;
 
-    /** @return void */
-    public function detach(SplObserver $observer);
+    /** @tentative-return-type */
+    public function detach(SplObserver $observer): void;
 
-    /** @return void */
-    public function notify();
+    /** @tentative-return-type */
+    public function notify(): void;
 }
 
 class SplObjectStorage implements Countable, Iterator, Serializable, ArrayAccess
 {
-    /** @return void */
-    public function attach(object $object, mixed $info = null) {}
+    /** @tentative-return-type */
+    public function attach(object $object, mixed $info = null): void {}
 
-    /** @return void */
-    public function detach(object $object) {}
+    /** @tentative-return-type */
+    public function detach(object $object): void {}
 
-    /** @return bool */
-    public function contains(object $object) {}
+    /** @tentative-return-type */
+    public function contains(object $object): bool {}
 
-    /** @return int */
-    public function addAll(SplObjectStorage $storage) {}
+    /** @tentative-return-type */
+    public function addAll(SplObjectStorage $storage): int {}
 
-    /** @return int */
-    public function removeAll(SplObjectStorage $storage) {}
+    /** @tentative-return-type */
+    public function removeAll(SplObjectStorage $storage): int {}
 
-    /** @return int */
-    public function removeAllExcept(SplObjectStorage $storage) {}
+    /** @tentative-return-type */
+    public function removeAllExcept(SplObjectStorage $storage): int {}
 
-    /** @return mixed */
-    public function getInfo() {}
+    /** @tentative-return-type */
+    public function getInfo(): mixed {}
 
-    /** @return void */
-    public function setInfo(mixed $info) {}
+    /** @tentative-return-type */
+    public function setInfo(mixed $info): void {}
 
-    /** @return int */
-    public function count(int $mode = COUNT_NORMAL) {}
+    /** @tentative-return-type */
+    public function count(int $mode = COUNT_NORMAL): int {}
 
-    /** @return void */
-    public function rewind() {}
+    /** @tentative-return-type */
+    public function rewind(): void {}
 
-    /** @return bool */
-    public function valid() {}
+    /** @tentative-return-type */
+    public function valid(): bool {}
 
-    /** @return int */
-    public function key() {}
+    /** @tentative-return-type */
+    public function key(): int {}
 
-    /** @return object */
-    public function current() {}
+    /** @tentative-return-type */
+    public function current(): object {}
 
-    /** @return void */
-    public function next() {}
+    /** @tentative-return-type */
+    public function next(): void {}
 
-    /** @return void */
-    public function unserialize(string $data) {}
+    /** @tentative-return-type */
+    public function unserialize(string $data): void {}
 
-    /** @return string */
-    public function serialize() {}
+    /** @tentative-return-type */
+    public function serialize(): string {}
 
     /**
      * @param object $object
-     * @return bool
+     * @tentative-return-type
      * @implementation-alias SplObjectStorage::contains
      * @no-verify Cannot specify arg type because ArrayAccess does not
      */
-    public function offsetExists($object) {}
+    public function offsetExists($object): bool {}
 
     /**
      * @param object $object
-     * @return mixed
+     * @tentative-return-type
      */
-    public function offsetGet($object) {}
+    public function offsetGet($object): mixed {}
 
     /**
      * @param object $object
-     * @return void
+     * @tentative-return-type
      * @implementation-alias SplObjectStorage::attach
      * @no-verify Cannot specify arg type because ArrayAccess does not
      */
-    public function offsetSet($object, mixed $info = null) {}
+    public function offsetSet(mixed $object, mixed $info = null): void {}
 
     /**
      * @param object $object
-     * @return void
+     * @tentative-return-type
      * @implementation-alias SplObjectStorage::detach
      * @no-verify Cannot specify arg type because ArrayAccess does not
      */
-    public function offsetUnset($object) {}
+    public function offsetUnset($object): void {}
 
-    /** @return string */
-    public function getHash(object $object) {}
+    /** @tentative-return-type */
+    public function getHash(object $object): string {}
 
-    /** @return array */
-    public function __serialize() {}
+    /** @tentative-return-type */
+    public function __serialize(): array {}
 
-    /** @return void */
-    public function __unserialize(array $data) {}
+    /** @tentative-return-type */
+    public function __unserialize(array $data): void {}
 
-    /** @return array */
-    public function __debugInfo() {}
+    /** @tentative-return-type */
+    public function __debugInfo(): array {}
 }
 
 class MultipleIterator implements Iterator
 {
     public function __construct(int $flags = MultipleIterator::MIT_NEED_ALL|MultipleIterator::MIT_KEYS_NUMERIC) {}
 
-    /** @return int */
-    public function getFlags() {}
+    /** @tentative-return-type */
+    public function getFlags(): int {}
 
-    /** @return void */
-    public function setFlags(int $flags) {}
+    /** @tentative-return-type */
+    public function setFlags(int $flags): void {}
 
-    /** @return void */
-    public function attachIterator(Iterator $iterator, string|int|null $info = null) {}
+    /** @tentative-return-type */
+    public function attachIterator(Iterator $iterator, string|int|null $info = null): void {}
 
-    /** @return void */
-    public function detachIterator(Iterator $iterator) {}
+    /** @tentative-return-type */
+    public function detachIterator(Iterator $iterator): void {}
 
-    /** @return bool */
-    public function containsIterator(Iterator $iterator) {}
+    /** @tentative-return-type */
+    public function containsIterator(Iterator $iterator): bool {}
 
-    /** @return int */
-    public function countIterators() {}
+    /** @tentative-return-type */
+    public function countIterators(): int {}
 
-    /** @return void */
-    public function rewind() {}
+    /** @tentative-return-type */
+    public function rewind(): void {}
 
-    /** @return bool */
-    public function valid() {}
+    /** @tentative-return-type */
+    public function valid(): bool {}
 
-    /** @return array */
-    public function key() {}
+    /** @tentative-return-type */
+    public function key(): array {}
 
-    /** @return array */
-    public function current() {}
+    /** @tentative-return-type */
+    public function current(): array {}
 
-    /** @return void */
-    public function next() {}
+    /** @tentative-return-type */
+    public function next(): void {}
 
     /**
-     * @return array
+     * @tentative-return-type
      * @implementation-alias SplObjectStorage::__debugInfo
      */
-    public function __debugInfo() {}
+    public function __debugInfo(): array {}
 }
diff --git a/ext/spl/spl_observer_arginfo.h b/ext/spl/spl_observer_arginfo.h
index fb5866d7881c5..5e9044a088f1e 100644
--- a/ext/spl/spl_observer_arginfo.h
+++ b/ext/spl/spl_observer_arginfo.h
@@ -1,31 +1,33 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: b82f26b4c1340b58c0faa31c5e14fef4c9778928 */
+ * Stub hash: a3c87f5b7edd257e25d6651628dd9896e14f5715 */
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObserver_update, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObserver_update, 0, 1, IS_VOID, 0)
 	ZEND_ARG_OBJ_INFO(0, subject, SplSubject, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplSubject_attach, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplSubject_attach, 0, 1, IS_VOID, 0)
 	ZEND_ARG_OBJ_INFO(0, observer, SplObserver, 0)
 ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplSubject_detach arginfo_class_SplSubject_attach
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplSubject_notify, 0, 0, 0)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplSubject_notify, 0, 0, IS_VOID, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage_attach, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_attach, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, object, IS_OBJECT, 0)
 	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, info, IS_MIXED, 0, "null")
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage_detach, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_detach, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, object, IS_OBJECT, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage_contains arginfo_class_SplObjectStorage_detach
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_contains, 0, 1, _IS_BOOL, 0)
+	ZEND_ARG_TYPE_INFO(0, object, IS_OBJECT, 0)
+ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage_addAll, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_addAll, 0, 1, IS_LONG, 0)
 	ZEND_ARG_OBJ_INFO(0, storage, SplObjectStorage, 0)
 ZEND_END_ARG_INFO()
 
@@ -33,89 +35,103 @@ ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplObjectStorage_removeAllExcept arginfo_class_SplObjectStorage_addAll
 
-#define arginfo_class_SplObjectStorage_getInfo arginfo_class_SplSubject_notify
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_getInfo, 0, 0, IS_MIXED, 0)
+ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage_setInfo, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_setInfo, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, info, IS_MIXED, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage_count, 0, 0, 0)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_count, 0, 0, IS_LONG, 0)
 	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, mode, IS_LONG, 0, "COUNT_NORMAL")
 ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplObjectStorage_rewind arginfo_class_SplSubject_notify
 
-#define arginfo_class_SplObjectStorage_valid arginfo_class_SplSubject_notify
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_valid, 0, 0, _IS_BOOL, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage_key arginfo_class_SplSubject_notify
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_key, 0, 0, IS_LONG, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage_current arginfo_class_SplSubject_notify
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_current, 0, 0, IS_OBJECT, 0)
+ZEND_END_ARG_INFO()
 
 #define arginfo_class_SplObjectStorage_next arginfo_class_SplSubject_notify
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage_unserialize, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_unserialize, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, data, IS_STRING, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage_serialize arginfo_class_SplSubject_notify
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_serialize, 0, 0, IS_STRING, 0)
+ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage_offsetExists, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_offsetExists, 0, 1, _IS_BOOL, 0)
 	ZEND_ARG_INFO(0, object)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage_offsetGet arginfo_class_SplObjectStorage_offsetExists
-
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage_offsetSet, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_offsetGet, 0, 1, IS_MIXED, 0)
 	ZEND_ARG_INFO(0, object)
+ZEND_END_ARG_INFO()
+
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_offsetSet, 0, 1, IS_VOID, 0)
+	ZEND_ARG_TYPE_INFO(0, object, IS_MIXED, 0)
 	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, info, IS_MIXED, 0, "null")
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage_offsetUnset arginfo_class_SplObjectStorage_offsetExists
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_offsetUnset, 0, 1, IS_VOID, 0)
+	ZEND_ARG_INFO(0, object)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage_getHash arginfo_class_SplObjectStorage_detach
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage_getHash, 0, 1, IS_STRING, 0)
+	ZEND_ARG_TYPE_INFO(0, object, IS_OBJECT, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage___serialize arginfo_class_SplSubject_notify
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage___serialize, 0, 0, IS_ARRAY, 0)
+ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_SplObjectStorage___unserialize, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_SplObjectStorage___unserialize, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, data, IS_ARRAY, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_SplObjectStorage___debugInfo arginfo_class_SplSubject_notify
+#define arginfo_class_SplObjectStorage___debugInfo arginfo_class_SplObjectStorage___serialize
 
 ZEND_BEGIN_ARG_INFO_EX(arginfo_class_MultipleIterator___construct, 0, 0, 0)
 	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, flags, IS_LONG, 0, "MultipleIterator::MIT_NEED_ALL | MultipleIterator::MIT_KEYS_NUMERIC")
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_MultipleIterator_getFlags arginfo_class_SplSubject_notify
+#define arginfo_class_MultipleIterator_getFlags arginfo_class_SplObjectStorage_key
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_MultipleIterator_setFlags, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_MultipleIterator_setFlags, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(0, flags, IS_LONG, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_MultipleIterator_attachIterator, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_MultipleIterator_attachIterator, 0, 1, IS_VOID, 0)
 	ZEND_ARG_OBJ_INFO(0, iterator, Iterator, 0)
 	ZEND_ARG_TYPE_MASK(0, info, MAY_BE_STRING|MAY_BE_LONG|MAY_BE_NULL, "null")
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_INFO_EX(arginfo_class_MultipleIterator_detachIterator, 0, 0, 1)
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_MultipleIterator_detachIterator, 0, 1, IS_VOID, 0)
 	ZEND_ARG_OBJ_INFO(0, iterator, Iterator, 0)
 ZEND_END_ARG_INFO()
 
-#define arginfo_class_MultipleIterator_containsIterator arginfo_class_MultipleIterator_detachIterator
+ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_MultipleIterator_containsIterator, 0, 1, _IS_BOOL, 0)
+	ZEND_ARG_OBJ_INFO(0, iterator, Iterator, 0)
+ZEND_END_ARG_INFO()
 
-#define arginfo_class_MultipleIterator_countIterators arginfo_class_SplSubject_notify
+#define arginfo_class_MultipleIterator_countIterators arginfo_class_SplObjectStorage_key
 
 #define arginfo_class_MultipleIterator_rewind arginfo_class_SplSubject_notify
 
-#define arginfo_class_MultipleIterator_valid arginfo_class_SplSubject_notify
+#define arginfo_class_MultipleIterator_valid arginfo_class_SplObjectStorage_valid
 
-#define arginfo_class_MultipleIterator_key arginfo_class_SplSubject_notify
+#define arginfo_class_MultipleIterator_key arginfo_class_SplObjectStorage___serialize
 
-#define arginfo_class_MultipleIterator_current arginfo_class_SplSubject_notify
+#define arginfo_class_MultipleIterator_current arginfo_class_SplObjectStorage___serialize
 
 #define arginfo_class_MultipleIterator_next arginfo_class_SplSubject_notify
 
-#define arginfo_class_MultipleIterator___debugInfo arginfo_class_SplSubject_notify
+#define arginfo_class_MultipleIterator___debugInfo arginfo_class_SplObjectStorage___serialize
 
 
 ZEND_METHOD(SplObjectStorage, attach);
diff --git a/ext/spl/tests/SplHeap_with_by_reference_compare.phpt b/ext/spl/tests/SplHeap_with_by_reference_compare.phpt
index b7b7b6d747a3c..bc4aa27e21c39 100644
--- a/ext/spl/tests/SplHeap_with_by_reference_compare.phpt
+++ b/ext/spl/tests/SplHeap_with_by_reference_compare.phpt
@@ -3,7 +3,7 @@ SplHeap using a compare function returning by-reference
 --FILE--
 <?php
 class Heap extends SplMinHeap {
-    public function &compare($a, $b) {
+    public function &compare($a, $b): int {
         return $a;
     }
 }
diff --git a/ext/spl/tests/SplObjectStorage_getHash.phpt b/ext/spl/tests/SplObjectStorage_getHash.phpt
index 85cdcb4e7a014..934243c77e8ed 100644
--- a/ext/spl/tests/SplObjectStorage_getHash.phpt
+++ b/ext/spl/tests/SplObjectStorage_getHash.phpt
@@ -9,6 +9,7 @@ $s[$o1] = "some_value\n";
 echo $s->offsetGet($o1);
 
 class MySplObjectStorage extends SplObjectStorage {
+    #[ReturnTypeWillChange]
     public function getHash($obj) {
         return 2;
     }
@@ -18,11 +19,11 @@ try {
     $s1 = new MySplObjectStorage;
     $s1[$o1] = "foo";
 } catch(Exception $e) {
-    echo "caught\n";
+    echo "caught 1\n";
 }
 
 class MySplObjectStorage2 extends SplObjectStorage {
-    public function getHash($obj) {
+    public function getHash($obj): string {
         throw new Exception("foo");
         return "asd";
     }
@@ -32,11 +33,11 @@ try {
     $s2 = new MySplObjectStorage2;
     $s2[$o2] = "foo";
 } catch(Exception $e) {
-    echo "caught\n";
+    echo "caught 2\n";
 }
 
 class MySplObjectStorage3 extends SplObjectStorage {
-    public function getHash($obj) {
+    public function getHash($obj): string {
         return "asd";
     }
 }
@@ -51,8 +52,8 @@ var_dump($s3[$o1] === $s3[$o2]);
 ?>
 --EXPECT--
 some_value
-caught
-caught
+caught 1
+caught 2
 object(stdClass)#2 (0) {
 }
 bool(true)
diff --git a/ext/spl/tests/SplObjectStorage_removeAllExcept_basic.phpt b/ext/spl/tests/SplObjectStorage_removeAllExcept_basic.phpt
index 83b3e27d88829..a6059da2958f2 100644
--- a/ext/spl/tests/SplObjectStorage_removeAllExcept_basic.phpt
+++ b/ext/spl/tests/SplObjectStorage_removeAllExcept_basic.phpt
@@ -5,21 +5,21 @@ Matthew Turland (me@matthewturland.com)
 --FILE--
 <?php
 
-    $a = (object) 'a';
-    $b = (object) 'b';
-    $c = (object) 'c';
+$a = (object) 'a';
+$b = (object) 'b';
+$c = (object) 'c';
 
-   $foo = new SplObjectStorage;
-    $foo->attach($a);
-    $foo->attach($b);
+$foo = new SplObjectStorage;
+$foo->attach($a);
+$foo->attach($b);
 
-    $bar = new SplObjectStorage;
-    $bar->attach($b);
-    $bar->attach($c);
+$bar = new SplObjectStorage;
+$bar->attach($b);
+$bar->attach($c);
 
-    $foo->removeAllExcept($bar);
-    var_dump($foo->contains($a));
-    var_dump($foo->contains($b));
+$foo->removeAllExcept($bar);
+var_dump($foo->contains($a));
+var_dump($foo->contains($b));
 
 ?>
 --EXPECT--
diff --git a/ext/spl/tests/bug64106.phpt b/ext/spl/tests/bug64106.phpt
index 26203c4e2e9a2..7476d7af7ff41 100644
--- a/ext/spl/tests/bug64106.phpt
+++ b/ext/spl/tests/bug64106.phpt
@@ -4,7 +4,7 @@ Bug #64106: Segfault on SplFixedArray[][x] = y when extended
 <?php
 
 class MyFixedArray extends SplFixedArray {
-    public function offsetGet($offset) { var_dump($offset); }
+    public function offsetGet($offset): mixed { var_dump($offset);  return null; }
 }
 
 $array = new MyFixedArray(10);
diff --git a/ext/spl/tests/bug67582.phpt b/ext/spl/tests/bug67582.phpt
index 331accbe7e72e..dc0cd532321e3 100644
--- a/ext/spl/tests/bug67582.phpt
+++ b/ext/spl/tests/bug67582.phpt
@@ -5,7 +5,7 @@ Bug #67582: Cloned SplObjectStorage with overwritten getHash fails offsetExists(
 
 class MyObjectStorage extends SplObjectStorage {
     // Overwrite getHash() with just some (working) test-method
-    public function getHash($object) { return get_class($object); }
+    public function getHash($object): string { return get_class($object); }
 }
 
 class TestObject {}
diff --git a/ext/spl/tests/bug69737.phpt b/ext/spl/tests/bug69737.phpt
index 02815c296a665..c3d4de78cb587 100644
--- a/ext/spl/tests/bug69737.phpt
+++ b/ext/spl/tests/bug69737.phpt
@@ -3,7 +3,7 @@ Bug #69737 (Segfault when SplMinHeap::compare produces fatal error)
 --FILE--
 <?php
 class SplMinHeap1 extends SplMinHeap {
-  public function compare($a, $b) {
+  public function compare($a, $b): int {
     return -parent::notexist($a, $b);
   }
 }
diff --git a/ext/spl/tests/heap_003.phpt b/ext/spl/tests/heap_003.phpt
index 69620af8efb7c..b864d373197e7 100644
--- a/ext/spl/tests/heap_003.phpt
+++ b/ext/spl/tests/heap_003.phpt
@@ -3,7 +3,7 @@ SPL: SplHeap: comparison callback
 --FILE--
 <?php
 class myHeap extends SplHeap {
-    public function compare($a, $b) {
+    public function compare($a, $b): int {
         if ($a > $b) {
             $result = 1;
         } else if ($a < $b) {
diff --git a/ext/spl/tests/heap_004.phpt b/ext/spl/tests/heap_004.phpt
index 892da20fb70e2..3db18b6733839 100644
--- a/ext/spl/tests/heap_004.phpt
+++ b/ext/spl/tests/heap_004.phpt
@@ -3,7 +3,7 @@ SPL: SplHeap: exceptions
 --FILE--
 <?php
 class myHeap extends SplHeap {
-    public function compare($a, $b) {
+    public function compare($a, $b): int {
         throw new exception("foo");
     }
 }
diff --git a/ext/spl/tests/heap_011.phpt b/ext/spl/tests/heap_011.phpt
index fae62585b0ebe..7413443cfce74 100644
--- a/ext/spl/tests/heap_011.phpt
+++ b/ext/spl/tests/heap_011.phpt
@@ -3,7 +3,7 @@ SPL: SplHeap with overridden compare()
 --FILE--
 <?php
 class SplMinHeap2 extends SplMinHeap {
-    public function compare($a, $b) {
+    public function compare($a, $b): int {
         return -parent::compare($a,$b);
     }
 }
@@ -15,7 +15,7 @@ $h->insert(2);
 var_dump($h->top());
 
 class SplMaxHeap2 extends SplMaxHeap {
-    public function compare($a, $b) {
+    public function compare($a, $b): int {
         return -parent::compare($a,$b);
     }
 }
diff --git a/ext/spl/tests/heap_corruption.phpt b/ext/spl/tests/heap_corruption.phpt
index 9b14a0fe0b09e..149d0b671996d 100644
--- a/ext/spl/tests/heap_corruption.phpt
+++ b/ext/spl/tests/heap_corruption.phpt
@@ -10,7 +10,7 @@ class myHeap extends SplHeap
 {
     public $allow_compare = true;
 
-    public function compare($v1, $v2)
+    public function compare($v1, $v2): int
     {
         if ($this->allow_compare == true)
         {
diff --git a/ext/spl/tests/heap_current_variation_001.phpt b/ext/spl/tests/heap_current_variation_001.phpt
index a55bb486e95ac..be9dc7bc1691d 100644
--- a/ext/spl/tests/heap_current_variation_001.phpt
+++ b/ext/spl/tests/heap_current_variation_001.phpt
@@ -8,7 +8,7 @@ Mike Sullivan <mikesul@php.net>
 
 class myHeap extends SplHeap
 {
-    public function compare($v1, $v2)
+    public function compare($v1, $v2): int
     {
         throw new Exception('');
     }
diff --git a/ext/spl/tests/heap_top_variation_002.phpt b/ext/spl/tests/heap_top_variation_002.phpt
index add363eab3121..0a9a8db613bed 100644
--- a/ext/spl/tests/heap_top_variation_002.phpt
+++ b/ext/spl/tests/heap_top_variation_002.phpt
@@ -7,7 +7,7 @@ TestFest London May 2009
 <?php
 // override heap to force corruption by throwing exception in compare
 class SplMinHeap2 extends SplMinHeap {
-    public function compare($a, $b) {
+    public function compare($a, $b): int {
         throw new Exception('Corrupt heap');
     }
 }
diff --git a/ext/spl/tests/observer_001.phpt b/ext/spl/tests/observer_001.phpt
index 72feb08a40cd6..baac666852c67 100644
--- a/ext/spl/tests/observer_001.phpt
+++ b/ext/spl/tests/observer_001.phpt
@@ -12,7 +12,7 @@ class ObserverImpl implements SplObserver
         $this->name = '$' . $name;
     }
 
-    function update(SplSubject $subject)
+    function update(SplSubject $subject): void
     {
         echo $this->name . '->' . __METHOD__ . '(' . $subject->getName() . ");\n";
     }
@@ -33,7 +33,7 @@ class SubjectImpl implements SplSubject
         $this->name = '$' . $name;
     }
 
-    function attach(SplObserver $observer)
+    function attach(SplObserver $observer): void
     {
         echo '$sub->' . __METHOD__ . '(' . $observer->getName() . ");\n";
         if (!in_array($observer, $this->observers))
@@ -42,7 +42,7 @@ class SubjectImpl implements SplSubject
         }
     }
 
-    function detach(SplObserver $observer)
+    function detach(SplObserver $observer): void
     {
         echo '$sub->' . __METHOD__ . '(' . $observer->getName() . ");\n";
         $idx = array_search($observer, $this->observers);
@@ -52,7 +52,7 @@ class SubjectImpl implements SplSubject
         }
     }
 
-    function notify()
+    function notify(): void
     {
         echo '$sub->' . __METHOD__ . "();\n";
         foreach($this->observers as $observer)
diff --git a/ext/spl/tests/observer_002.phpt b/ext/spl/tests/observer_002.phpt
index 2642c28bd57c7..858bbc8c94def 100644
--- a/ext/spl/tests/observer_002.phpt
+++ b/ext/spl/tests/observer_002.phpt
@@ -5,31 +5,31 @@ SPL: SplObjectStorage
 
 class MyObjectStorage extends SplObjectStorage
 {
-    function rewind()
+    function rewind(): void
     {
         echo __METHOD__ . "()\n";
         parent::rewind();
     }
 
-    function valid()
+    function valid(): bool
     {
         echo __METHOD__ . "(" . (parent::valid() ? 1 : 0) . ")\n";
         return parent::valid();
     }
 
-    function key()
+    function key(): int
     {
         echo __METHOD__ . "(" . parent::key() . ")\n";
         return parent::key();
     }
 
-    function current()
+    function current(): object
     {
         echo __METHOD__ . "(" . parent::current()->getName() . ")\n";
         return parent::current();
     }
 
-    function next()
+    function next(): void
     {
         echo __METHOD__ . "()\n";
         parent::next();
@@ -45,7 +45,7 @@ class ObserverImpl implements SplObserver
         $this->name = '$' . $name;
     }
 
-    function update(SplSubject $subject)
+    function update(SplSubject $subject): void
     {
         echo $this->name . '->' . __METHOD__ . '(' . $subject->getName() . ");\n";
     }
@@ -67,13 +67,13 @@ class SubjectImpl implements SplSubject
         $this->name = '$' . $name;
     }
 
-    function attach(SplObserver $observer)
+    function attach(SplObserver $observer): void
     {
         echo $this->name . '->' . __METHOD__ . '(' . $observer->getName() . ");\n";
         $this->observers->attach($observer);
     }
 
-    function detach(SplObserver $observer)
+    function detach(SplObserver $observer): void
     {
         echo $this->name . '->' . __METHOD__ . '(' . $observer->getName() . ");\n";
         $this->observers->detach($observer);
@@ -84,7 +84,7 @@ class SubjectImpl implements SplSubject
         return $this->observers->count();
     }
 
-    function notify()
+    function notify(): void
     {
         echo $this->name . '->' . __METHOD__ . "();\n";
         foreach($this->observers as $key => $observer)
diff --git a/ext/spl/tests/observer_008.phpt b/ext/spl/tests/observer_008.phpt
index a584d5492ccbc..0f6f0d263b9e8 100644
--- a/ext/spl/tests/observer_008.phpt
+++ b/ext/spl/tests/observer_008.phpt
@@ -12,7 +12,7 @@ $a = new A;
 $a->attach($o1);
 $a->attach($o2);
 
-$b = new SplObjectSTorage();
+$b = new SplObjectStorage();
 $b->attach($o2);
 $b->attach($o3);
 
diff --git a/ext/spl/tests/pqueue_002.phpt b/ext/spl/tests/pqueue_002.phpt
index ee9a5f30caeff..df4a64f4b2d03 100644
--- a/ext/spl/tests/pqueue_002.phpt
+++ b/ext/spl/tests/pqueue_002.phpt
@@ -3,7 +3,7 @@ SPL: SplPriorityQueue: exceptions
 --FILE--
 <?php
 class myPQueue extends SplPriorityQueue {
-    public function compare($a, $b) {
+    public function compare($a, $b): int {
         throw new exception("foo");
     }
 }
diff --git a/ext/spl/tests/spl_heap_count_basic.phpt b/ext/spl/tests/spl_heap_count_basic.phpt
index 2be8c432fcd96..e8be968e06d4b 100644
--- a/ext/spl/tests/spl_heap_count_basic.phpt
+++ b/ext/spl/tests/spl_heap_count_basic.phpt
@@ -8,12 +8,12 @@ Chris Scott chris.scott@nstein.com
 
 class MyHeap extends SplHeap
 {
-    public function compare($a,$b)
+    public function compare($a,$b): int
     {
         return ($a < $b);
     }
 
-    public function count() // override count to force failure
+    public function count(): int // override count to force failure
     {
         throw new Exception('Cause count to fail');
         return parent::count();
diff --git a/ext/spl/tests/spl_heap_is_empty_basic.phpt b/ext/spl/tests/spl_heap_is_empty_basic.phpt
index abf64f8d9d601..0a5df4e8843cb 100644
--- a/ext/spl/tests/spl_heap_is_empty_basic.phpt
+++ b/ext/spl/tests/spl_heap_is_empty_basic.phpt
@@ -8,7 +8,7 @@ Nathaniel McHugh nat@fishtrap.co.uk
 
 class MyHeap extends SplHeap{
 
-public function compare($a, $b){
+public function compare($a, $b): int {
 return $a < $b;
 }
 
diff --git a/ext/spl/tests/spl_heap_iteration_error.phpt b/ext/spl/tests/spl_heap_iteration_error.phpt
index 1202856c7bbaa..c11cf57dc4665 100644
--- a/ext/spl/tests/spl_heap_iteration_error.phpt
+++ b/ext/spl/tests/spl_heap_iteration_error.phpt
@@ -7,7 +7,7 @@ Lukasz Andrzejak meltir@meltir.com
 <?php
 class ext_heap extends SplMaxHeap {
   public $fail = false;
-  public function compare($val1,$val2) {
+  public function compare($val1,$val2): int {
     if ($this->fail)
       throw new Exception('Corrupting heap',99);
     return 0;
diff --git a/ext/spl/tests/spl_pq_top_error_corrupt.phpt b/ext/spl/tests/spl_pq_top_error_corrupt.phpt
index 838e763447f88..60f532b02fe88 100644
--- a/ext/spl/tests/spl_pq_top_error_corrupt.phpt
+++ b/ext/spl/tests/spl_pq_top_error_corrupt.phpt
@@ -8,7 +8,7 @@ Nathaniel McHugh nat@fishtrap.co.uk
 
 class myPriorityQueue extends SplPriorityQueue{
 
-    public function compare($a, $b){
+    public function compare($a, $b): int {
          if ($b == 2) {
         throw new Exception('ignore me');
         }  else {