Fixed bug causing exception not being thrown immediately into a generator yielding from an array

NEWS

@@ -16,6 +16,8 @@ PHP                                                                        NEWS
     to not be accepted as type name. (Bob)
   . Fixed bug #70904 (yield from incorrectly marks valid generator as finished).
     (Bob)
+  . Fixed exception not being thrown immediately into a generator yielding
+    from an array. (Bob)
 
 - Mysqlnd:
   . Fixed bug #68077 (LOAD DATA LOCAL INFILE / open_basedir restriction).

Zend/tests/generators/throw_into_yield_from_array.phpt

@@ -0,0 +1,43 @@
+--TEST--
+Throwing into a generator yielding from an array/iterator
+--FILE--
+<?php
+
+$data = [1, 2, 3];
+
+function yielditer($arr) {
+	foreach($arr as $val) {
+		yield $val;
+	}
+}
+
+function yf($in) {
+	yield from $in;
+}
+
+function test($g) {
+	var_dump($g->current());
+	try {
+		$g->throw(new Exception("Exception!"));
+	} catch (Exception $e) {
+		echo "{$e->getMessage()}\n";
+	}
+	var_dump($g->current());
+}
+
+$yfiter = yf($data);
+$yfgen = yf(yielditer($data));
+
+test(yf($data));
+echo "\n";
+test(yf(yielditer($data)));
+
+?>
+--EXPECT--
+int(1)
+Exception!
+NULL
+
+int(1)
+Exception!
+NULL

Zend/zend_generators.c

@@ -287,6 +287,12 @@ ZEND_API zend_execute_data *zend_generator_check_placeholder_frame(zend_execute_
 
 static void zend_generator_throw_exception(zend_generator *generator, zval *exception)
 {
+	/* if we don't stop an array/iterator yield from, the exception will only reach the generator after the values were all iterated over */
+	if (UNEXPECTED(Z_TYPE(generator->values) != IS_UNDEF)) {
+		zval_ptr_dtor(&generator->values);
+		ZVAL_UNDEF(&generator->values);
+	}
+
 	/* Throw the exception in the context of the generator. Decrementing the opline
 	 * to pretend the exception happened during the YIELD opcode. */
 	zend_execute_data *original_execute_data = EG(current_execute_data);