ext/spl: Add trampoline test for iterator_apply()

ext/spl/tests/spl_iterator_apply_with_trampoline.phpt

@@ -0,0 +1,48 @@
+--TEST--
+SPL: iterator_apply() with a trampoline
+--FILE--
+<?php
+
+class TrampolineTest {
+    public function __call(string $name, array $arguments) {
+        echo 'Trampoline for ', $name, PHP_EOL;
+        var_dump($arguments);
+        if ($name === 'trampolineThrow') {
+            throw new Exception('boo');
+        }
+    }
+}
+$o = new TrampolineTest();
+$callback = [$o, 'trampoline'];
+$callbackThrow = [$o, 'trampolineThrow'];
+
+$it = new RecursiveArrayIterator([1, 21, 22]);
+
+try {
+    $iterations = iterator_apply($it, $callback);
+    var_dump($iterations);
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+try {
+    iterator_apply($it, $callbackThrow);
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+try {
+    iterator_apply($it, $callback, 'not an array');
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+
+?>
+--EXPECT--
+Trampoline for trampoline
+array(0) {
+}
+int(1)
+Trampoline for trampolineThrow
+array(0) {
+}
+Exception: boo
+TypeError: iterator_apply(): Argument #3 ($args) must be of type ?array, string given