Fix uouv on oom on object allocation

We should initialize object handlers before trying to allocate more memory,
because if we OOM we'll look for the free_obj handler which has not been
initialized. Furthermore, free_obj can run before the object is fully
initialized, requiring guards for potentially unset fields.

Fixes GH-11734

Zend/tests/new_oom.inc

@@ -0,0 +1,14 @@
+<?php
+
+ini_set('memory_limit', '1M');
+
+$class = $argv[1];
+$objects = [];
+
+try {
+    while (true) {
+        $rc = new ReflectionClass($class);
+        $objects[] = $rc->newInstanceWithoutConstructor();
+    }
+} catch (Throwable) {
+}

Zend/tests/new_oom.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Test OOM on new of each class
+--SKIPIF--
+<?php
+if (getenv("SKIP_SLOW_TESTS")) die('skip slow test');
+?>
+--FILE--
+<?php
+
+$file = __DIR__ . '/new_oom.inc';
+$php = PHP_BINARY;
+
+foreach (get_declared_classes() as $class) {
+    $output = shell_exec("$php $file $class");
+    if ($output && preg_match('(^\nFatal error: Allowed memory size of [0-9]+ bytes exhausted[^\r\n]* \(tried to allocate [0-9]+ bytes\) in [^\r\n]+ on line [0-9]+$)', $output) !== 1) {
+        echo "Class $class failed\n";
+        echo $output;
+    }
+}
+
+?>
+===DONE===
+--EXPECT--
+===DONE===

ext/spl/spl_heap.c

@@ -385,6 +385,11 @@ static spl_ptr_heap *spl_ptr_heap_clone(spl_ptr_heap *from) { /* {{{ */
 static void spl_ptr_heap_destroy(spl_ptr_heap *heap) { /* {{{ */
 	int i;
 
+	/* Heap might be null if we OOMed during object initialization. */
+	if (!heap) {
+		return;
+	}
+
 	for (i = 0; i < heap->count; ++i) {
 		heap->dtor(spl_heap_elem(heap, i));
 	}
@@ -438,18 +443,18 @@ static zend_object *spl_heap_object_new_ex(zend_class_entry *class_type, zend_ob
 
 	while (parent) {
 		if (parent == spl_ce_SplPriorityQueue) {
-			intern->heap = spl_ptr_heap_init(spl_ptr_pqueue_elem_cmp, spl_ptr_heap_pqueue_elem_ctor, spl_ptr_heap_pqueue_elem_dtor, sizeof(spl_pqueue_elem));
 			intern->std.handlers = &spl_handler_SplPriorityQueue;
+			intern->heap = spl_ptr_heap_init(spl_ptr_pqueue_elem_cmp, spl_ptr_heap_pqueue_elem_ctor, spl_ptr_heap_pqueue_elem_dtor, sizeof(spl_pqueue_elem));
 			intern->flags = SPL_PQUEUE_EXTR_DATA;
 			break;
 		}
 
 		if (parent == spl_ce_SplMinHeap || parent == spl_ce_SplMaxHeap
 				|| parent == spl_ce_SplHeap) {
+			intern->std.handlers = &spl_handler_SplHeap;
 			intern->heap = spl_ptr_heap_init(
 				parent == spl_ce_SplMinHeap ? spl_ptr_heap_zval_min_cmp : spl_ptr_heap_zval_max_cmp,
 				spl_ptr_heap_zval_ctor, spl_ptr_heap_zval_dtor, sizeof(zval));
-			intern->std.handlers = &spl_handler_SplHeap;
 			break;
 		}