Merge branch 'PHP-8.1'

* PHP-8.1:
  Fixed type inference for FETCH_DIM_W without use

Author: dstogov

Zend/Optimizer/zend_inference.c

@@ -3385,6 +3385,10 @@ static zend_always_inline zend_result _zend_update_type_info(
 						|| opline->opcode == ZEND_FETCH_DIM_FUNC_ARG
 						|| opline->opcode == ZEND_FETCH_LIST_W) {
 					j = ssa_vars[ssa_op->result_def].use_chain;
+					if (j < 0) {
+						/* no uses */
+						tmp |= key_type | MAY_BE_ARRAY | MAY_BE_ARRAY_OF_NULL;
+					}
 					while (j >= 0) {
 						zend_uchar opcode;
 

ext/opcache/tests/jit/fetch_dim_w_002.phpt

@@ -0,0 +1,17 @@
+--TEST--
+JIT FETCH_DIM_W: 002
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.file_update_protection=0
+opcache.jit_buffer_size=1M
+--FILE--
+<?php
+function test() {
+    $b = [&$a[0]];
+}
+test();
+?>
+DONE
+--EXPECT--
+DONE