From e588f242768a5fe385c4b8539be5350db1d42957 Mon Sep 17 00:00:00 2001
From: Dmitry Stogov <dmitry@zend.com>
Date: Wed, 22 Sep 2021 15:30:30 +0300
Subject: [PATCH] Fixed type inference

---
 ext/opcache/Optimizer/zend_inference.c    |  3 +++
 ext/opcache/tests/jit/assign_dim_003.phpt | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 ext/opcache/tests/jit/assign_dim_003.phpt

diff --git a/ext/opcache/Optimizer/zend_inference.c b/ext/opcache/Optimizer/zend_inference.c
index e34d4db9ab9..3ac243c30a3 100644
--- a/ext/opcache/Optimizer/zend_inference.c
+++ b/ext/opcache/Optimizer/zend_inference.c
@@ -2754,6 +2754,9 @@ static zend_always_inline int _zend_update_type_info(
 				if (t1 & ((MAY_BE_ANY|MAY_BE_UNDEF) - MAY_BE_STRING)) {
 					tmp |= (OP1_DATA_INFO() & (MAY_BE_ANY | MAY_BE_ARRAY_KEY_ANY | MAY_BE_ARRAY_OF_ANY | MAY_BE_ARRAY_OF_REF));
 
+					if (OP1_DATA_INFO() & MAY_BE_UNDEF) {
+						tmp |= MAY_BE_NULL;
+					}
 					if (opline->op2_type == IS_UNUSED) {
 						/* When appending to an array and the LONG_MAX key is already used
 						 * null will be returned. */
diff --git a/ext/opcache/tests/jit/assign_dim_003.phpt b/ext/opcache/tests/jit/assign_dim_003.phpt
new file mode 100644
index 00000000000..ab3d4d00fa8
--- /dev/null
+++ b/ext/opcache/tests/jit/assign_dim_003.phpt
@@ -0,0 +1,20 @@
+--TEST--
+JIT ASSIGN_DIM: 003
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.file_update_protection=0
+opcache.jit_buffer_size=1M
+opcache.jit=tracing
+--SKIPIF--
+<?php require_once('skipif.inc'); ?>
+--FILE--
+<?php
+function test() {
+    var_dump($a[0] = $v);
+}
+test();
+?>
+--EXPECTF--
+Warning: Undefined variable $v in %sassign_dim_003.php on line 3
+NULL
\ No newline at end of file