Implement Closure::getCurrent() to retrieve current closure

Fixes GH-18163

Author: iluuu1994

Zend/tests/closures/closure_get_current.phpt

@@ -0,0 +1,53 @@
+--TEST--
+Closure::getCurrent()
+--FILE--
+<?php
+
+$i = 1;
+
+$c = function ($p) use (&$i) {
+    $self = Closure::getCurrent();
+    var_dump($p, $i);
+    $i++;
+    if ($p < 10) {
+        $self($p + 1);
+    }
+};
+
+$c(1);
+var_dump($i);
+
+function fail() {
+    Closure::getCurrent();
+}
+
+try {
+    fail();
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+int(1)
+int(1)
+int(2)
+int(2)
+int(3)
+int(3)
+int(4)
+int(4)
+int(5)
+int(5)
+int(6)
+int(6)
+int(7)
+int(7)
+int(8)
+int(8)
+int(9)
+int(9)
+int(10)
+int(10)
+int(11)
+Current function is not a closure

Zend/zend_closures.c

@@ -418,6 +418,23 @@ ZEND_METHOD(Closure, fromCallable)
 }
 /* }}} */
 
+ZEND_METHOD(Closure, getCurrent)
+{
+	ZEND_PARSE_PARAMETERS_NONE();
+
+	zend_execute_data *prev_ex = EX(prev_execute_data);
+
+	if (!prev_ex
+	 || !prev_ex->func
+	 || !(prev_ex->func->common.fn_flags & ZEND_ACC_CLOSURE)) {
+			zend_throw_error(NULL, "Current function is not a closure");
+			RETURN_THROWS();
+	}
+
+	zend_object *obj = ZEND_CLOSURE_OBJECT(prev_ex->func);
+	RETURN_OBJ_COPY(obj);
+}
+
 static ZEND_COLD zend_function *zend_closure_get_constructor(zend_object *object) /* {{{ */
 {
 	zend_throw_error(NULL, "Instantiation of class Closure is not allowed");

Zend/zend_closures.stub.php

@@ -21,4 +21,6 @@ public function bindTo(?object $newThis, object|string|null $newScope = "static"
     public function call(object $newThis, mixed ...$args): mixed {}
 
     public static function fromCallable(callable $callback): Closure {}
+
+    public static function getCurrent(): Closure {}
 }