core: Deprecate using null as an array offset and when calling array_key_exists() (#19511)

RFC: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_using_values_null_as_an_array_offset_and_when_calling_array_key_exists

Zend/tests/assign_dim_op_undef.phpt

@@ -10,6 +10,8 @@ Warning: Undefined variable $a in %s on line %d
 
 Warning: Undefined variable $b in %s on line %d
 
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
 Warning: Undefined array key "" in %s on line %d
 array(1) {
   [""]=>

Zend/tests/bug72543_2.phpt

@@ -9,7 +9,8 @@ unset($ref);
 $arr[0][$arr[0]] = null;
 var_dump($arr);
 ?>
---EXPECT--
+--EXPECTF--
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 array(1) {
   [0]=>
   array(1) {

Zend/tests/gc/bug67314.phpt

@@ -17,7 +17,11 @@ echo "ok\n";
 ?>
 --EXPECTF--
 Warning: Undefined variable $i in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 made it once
 
 Warning: Undefined variable $i in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 ok

Zend/tests/isset/isset_array.phpt

@@ -42,6 +42,8 @@ bool(true)
 Deprecated: Implicit conversion from float 0.6 to int loses precision in %s on line %d
 bool(true)
 bool(false)
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Resource ID#%d used as offset, casting to integer (%d) in %s on line %d

Zend/tests/list/list_keyed_conversions.phpt

@@ -21,6 +21,8 @@ list(STDIN => $resource) = [];
 
 ?>
 --EXPECTF--
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
 Deprecated: Implicit conversion from float 1.5 to int loses precision in %s on line %d
 string(0) ""
 int(1)

Zend/tests/offset_array.phpt

@@ -38,6 +38,8 @@ int(2)
 Deprecated: Implicit conversion from float 0.0836 to int loses precision in %s on line %d
 int(1)
 
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
 Warning: Undefined array key "" in %s on line %d
 NULL
 

Zend/tests/offsets/ArrayObject_container_offset_behaviour.phpt

@@ -132,6 +132,93 @@ OUTPUT;
 
 $EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTF_OUTPUT_FLOAT_OFFSETS) . '$/s';
 
+const EXPECTED_OUTPUT_NULL_OFFSETS = <<<OUTPUT
+Read before write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Warning: Undefined array key "" in %s on line %d
+NULL
+Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Read:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(5)
+Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(false)
+null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(25)
+Reference to dimension:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Value of reference:
+int(25)
+Value of container dimension after write to reference (should be int(100) if successful):
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(100)
+unset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested read:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Warning: Undefined array key "" in %s on line %d
+
+Warning: Trying to access array offset on null in %s on line %d
+NULL
+Nested write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Nested empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(false)
+Nested null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(30)
+Nested unset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+OUTPUT;
+
+$EXPECTED_OUTPUT_NULL_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTED_OUTPUT_NULL_OFFSETS) . '$/s';
+
 const EXPECTED_OUTPUT_INVALID_OFFSETS = <<<OUTPUT
 Read before write:
 Cannot access offset of type %s on ArrayObject
@@ -175,44 +262,86 @@ $EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTED_OUTPUT
 const EXPECTED_OUTPUT_NULL_OFFSET = <<<OUTPUT
 Read before write:
 
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 8
+
 Warning: Undefined array key "" in %s on line 8
 NULL
 Write:
 Read:
 
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 22
+
 Warning: Undefined array key "" in %s on line 22
 NULL
 Read-Write:
 
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 29
+
 Warning: Undefined array key "" in %s on line 29
 isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 36
 bool(false)
 empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 42
 bool(true)
 null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 48
 string(7) "default"
 Reference to dimension:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 55
 Value of reference:
 NULL
 Value of container dimension after write to reference (should be int(100) if successful):
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 60
 int(100)
 unset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 67
 Nested read:
 
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 74
+
 Warning: Undefined array key "" in %s on line 74
 
 Warning: Trying to access array offset on null in %s on line 74
 NULL
 Nested write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 81
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 81
 Nested Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 88
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 88
 Nested isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 95
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 95
 bool(true)
 Nested empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 101
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 101
 bool(false)
 Nested null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 107
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 107
 int(30)
 Nested unset():
 
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line 114
+
 OUTPUT;
 
 const EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS = <<<OUTPUT
@@ -323,6 +452,7 @@ foreach ($offsets as $dimension) {
         !preg_match($EXPECTED_OUTPUT_VALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX, $varOutput)
+        && !preg_match($EXPECTED_OUTPUT_NULL_OFFSETS_REGEX, $varOutput)
         && $varOutput !== EXPECTED_OUTPUT_NULL_OFFSET
         && $varOutput !== EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS
     ) {
@@ -354,6 +484,7 @@ foreach ($offsets as $offset) {
         !preg_match($EXPECTED_OUTPUT_VALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX, $varOutput)
+        && !preg_match($EXPECTED_OUTPUT_NULL_OFFSETS_REGEX, $varOutput)
         && $varOutput !== EXPECTED_OUTPUT_NULL_OFFSET
         && $varOutput !== EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS
     ) {

Zend/tests/offsets/array_container_offset_behaviour.phpt

@@ -132,6 +132,89 @@ OUTPUT;
 
 $EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTF_OUTPUT_FLOAT_OFFSETS) . '$/s';
 
+const EXPECTED_OUTPUT_NULL_OFFSETS = <<<OUTPUT
+Read before write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Warning: Undefined array key "" in %s on line %d
+NULL
+Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Read:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(5)
+Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(false)
+null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(25)
+Reference to dimension:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Value of reference:
+int(25)
+Value of container dimension after write to reference (should be int(100) if successful):
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(100)
+unset():
+Nested read:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Warning: Undefined array key "" in %s on line %d
+
+Warning: Trying to access array offset on null in %s on line %d
+NULL
+Nested write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Nested empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(false)
+Nested null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(30)
+Nested unset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+OUTPUT;
+
+$EXPECTED_OUTPUT_NULL_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTED_OUTPUT_NULL_OFFSETS) . '$/s';
+
 const EXPECTED_OUTPUT_INVALID_OFFSETS = <<<OUTPUT
 Read before write:
 Cannot access offset of type %s on array
@@ -273,6 +356,7 @@ foreach ($offsets as $dimension) {
         !preg_match($EXPECTED_OUTPUT_VALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX, $varOutput)
+        && !preg_match($EXPECTED_OUTPUT_NULL_OFFSETS_REGEX, $varOutput)
         && $varOutput !== EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS
     ) {
         file_put_contents(__DIR__ . DIRECTORY_SEPARATOR . "debug_array_container_{$failuresNb}.txt", $varOutput);
@@ -300,6 +384,7 @@ foreach ($offsets as $offset) {
         !preg_match($EXPECTED_OUTPUT_VALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX, $varOutput)
+        && !preg_match($EXPECTED_OUTPUT_NULL_OFFSETS_REGEX, $varOutput)
         && $varOutput !== EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS
     ) {
         file_put_contents(__DIR__ . DIRECTORY_SEPARATOR . "debug_array_container_{$failuresNb}.txt", $varOutput);

Zend/tests/offsets/false_container_offset_behaviour.phpt

@@ -135,6 +135,89 @@ OUTPUT;
 
 $EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTF_OUTPUT_FLOAT_OFFSETS) . '$/s';
 
+const EXPECTED_OUTPUT_NULL_OFFSETS = <<<OUTPUT
+Read before write:
+
+Warning: Trying to access array offset on false in %s on line 8
+NULL
+Write:
+
+Deprecated: Automatic conversion of false to array is deprecated in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Read:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(5)
+Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(false)
+null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(25)
+Reference to dimension:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Value of reference:
+int(25)
+Value of container dimension after write to reference (should be int(100) if successful):
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(100)
+unset():
+Nested read:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Warning: Undefined array key "" in %s on line %d
+
+Warning: Trying to access array offset on null in %s on line %d
+NULL
+Nested write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Nested empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(false)
+Nested null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(30)
+Nested unset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+OUTPUT;
+
+$EXPECTED_OUTPUT_NULL_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTED_OUTPUT_NULL_OFFSETS) . '$/s';
+
 const EXPECTED_OUTPUT_INVALID_OFFSETS = <<<OUTPUT
 Read before write:
 
@@ -280,6 +363,7 @@ foreach ($offsets as $dimension) {
         !preg_match($EXPECTED_OUTPUT_VALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX, $varOutput)
+        && !preg_match($EXPECTED_OUTPUT_NULL_OFFSETS_REGEX, $varOutput)
         && $varOutput !== EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS
     ) {
         file_put_contents(__DIR__ . DIRECTORY_SEPARATOR . "debug_false_container_{$failuresNb}.txt", $varOutput);
@@ -307,6 +391,7 @@ foreach ($offsets as $offset) {
         !preg_match($EXPECTED_OUTPUT_VALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX, $varOutput)
+        && !preg_match($EXPECTED_OUTPUT_NULL_OFFSETS_REGEX, $varOutput)
         && $varOutput !== EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS
     ) {
         file_put_contents(__DIR__ . DIRECTORY_SEPARATOR . "debug_false_container_{$failuresNb}.txt", $varOutput);

Zend/tests/offsets/null_container_offset_behaviour.phpt

@@ -131,6 +131,87 @@ OUTPUT;
 
 $EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTF_OUTPUT_FLOAT_OFFSETS) . '$/s';
 
+const EXPECTED_OUTPUT_NULL_OFFSETS = <<<OUTPUT
+Read before write:
+
+Warning: Trying to access array offset on null in %s on line %d
+NULL
+Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Read:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(5)
+Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(false)
+null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(25)
+Reference to dimension:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Value of reference:
+int(25)
+Value of container dimension after write to reference (should be int(100) if successful):
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(100)
+unset():
+Nested read:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Warning: Undefined array key "" in %s on line %d
+
+Warning: Trying to access array offset on null in %s on line %d
+NULL
+Nested write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested Read-Write:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Nested isset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Nested empty():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(false)
+Nested null coalesce:
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+int(30)
+Nested unset():
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+OUTPUT;
+
+$EXPECTED_OUTPUT_NULL_OFFSETS_REGEX = '/^' . expectf_to_regex(EXPECTED_OUTPUT_NULL_OFFSETS) . '$/s';
+
 const EXPECTED_OUTPUT_INVALID_OFFSETS = <<<OUTPUT
 Read before write:
 
@@ -272,6 +353,7 @@ foreach ($offsets as $dimension) {
         !preg_match($EXPECTED_OUTPUT_VALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX, $varOutput)
+        && !preg_match($EXPECTED_OUTPUT_NULL_OFFSETS_REGEX, $varOutput)
         && $varOutput !== EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS
     ) {
         file_put_contents(__DIR__ . DIRECTORY_SEPARATOR . "debug_null_container_{$failuresNb}.txt", $varOutput);
@@ -299,6 +381,7 @@ foreach ($offsets as $offset) {
         !preg_match($EXPECTED_OUTPUT_VALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_INVALID_OFFSETS_REGEX, $varOutput)
         && !preg_match($EXPECTED_OUTPUT_FLOAT_OFFSETS_REGEX, $varOutput)
+        && !preg_match($EXPECTED_OUTPUT_NULL_OFFSETS_REGEX, $varOutput)
         && $varOutput !== EXPECTED_OUTPUT_RESOURCE_STDERR_OFFSETS
     ) {
         file_put_contents(__DIR__ . DIRECTORY_SEPARATOR . "debug_null_container_{$failuresNb}.txt", $varOutput);

Zend/tests/offsets/null_offset_no_uaf.phpt

@@ -0,0 +1,17 @@
+--TEST--
+No UAF on null offset
+--FILE--
+<?php
+set_error_handler(function($errno, $errstr) {
+    global $ary;
+    $ary = null;
+    echo $errstr;
+});
+
+$ary[null] = 1;
+
+echo "\nSuccess\n";
+?>
+--EXPECTF--
+Using null as an array offset is deprecated, use an empty string instead
+Success

Zend/tests/unset_empty_isset_comprehensive.phpt

@@ -703,12 +703,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -730,12 +736,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -757,12 +769,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -784,12 +802,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -817,12 +841,18 @@ array(3) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(3) {
   [1]=>
@@ -841,12 +871,18 @@ array(2) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(2) {
   [2]=>
@@ -861,12 +897,18 @@ array(1) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(1) {
   [3]=>
@@ -877,12 +919,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -908,12 +956,18 @@ array(2) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(2) {
   [1]=>
@@ -928,12 +982,18 @@ array(1) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(1) {
   [2]=>
@@ -944,12 +1004,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -973,12 +1039,18 @@ array(1) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(1) {
   [2]=>
@@ -989,12 +1061,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -1018,12 +1096,18 @@ array(1) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(1) {
   ["Age"]=>
@@ -1034,12 +1118,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -1069,12 +1159,18 @@ array(4) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(4) {
   [1]=>
@@ -1097,12 +1193,18 @@ array(3) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(3) {
   ["One"]=>
@@ -1121,12 +1223,18 @@ array(2) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(2) {
   [2]=>
@@ -1141,12 +1249,18 @@ array(1) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(1) {
   [""]=>
@@ -1157,12 +1271,18 @@ array(0) {
 }
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 Warning: Undefined variable $key_val in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 bool(true)
 array(0) {
 }
@@ -1175,11 +1295,11 @@ bool(true)
 
 *** Testing unset(), empty() & isset() with resource variables ***
 -- Iteration 1 --
-resource(%d) of type (stream)
+resource(5) of type (stream)
 bool(true)
 bool(false)
 bool(true)
-resource(%d) of type (stream)
+resource(5) of type (stream)
 bool(false)
 bool(true)
 bool(false)
@@ -1188,11 +1308,11 @@ bool(false)
 Warning: Undefined variable $resource in %s on line %d
 NULL
 -- Iteration 2 --
-resource(%d) of type (stream)
+resource(6) of type (stream)
 bool(true)
 bool(false)
 bool(true)
-resource(%d) of type (stream)
+resource(6) of type (stream)
 bool(false)
 bool(true)
 bool(false)
@@ -1207,7 +1327,7 @@ bool(false)
 bool(true)
 
 *** Testing unset(), empty() & isset() with objects ***
-object(Point)#%d (3) {
+object(Point)#1 (3) {
   ["x"]=>
   int(30)
   ["y"]=>
@@ -1229,7 +1349,7 @@ bool(false)
 
 Warning: Undefined variable $lable in %s on line %d
 bool(true)
-object(Point)#%d (3) {
+object(Point)#1 (3) {
   ["x"]=>
   int(30)
   ["y"]=>
@@ -1237,7 +1357,7 @@ object(Point)#%d (3) {
   ["lable"]=>
   string(6) "Point1"
 }
-object(Point)#%d (2) {
+object(Point)#1 (2) {
   ["y"]=>
   int(40)
   ["lable"]=>
@@ -1245,7 +1365,7 @@ object(Point)#%d (2) {
 }
 bool(false)
 bool(true)
-object(Point)#%d (0) {
+object(Point)#1 (0) {
 }
 bool(true)
 bool(false)
@@ -1266,7 +1386,7 @@ array(3) {
   [2]=>
   string(9) "testPoint"
 }
-object(Point)#%d (3) {
+object(Point)#1 (3) {
   ["x"]=>
   int(5)
   ["y"]=>

Zend/zend_execute.c

@@ -2629,6 +2629,21 @@ static zend_never_inline uint8_t slow_index_convert(HashTable *ht, const zval *d
 			ZEND_FALLTHROUGH;
 		}
 		case IS_NULL:
+			/* The array may be destroyed while throwing the notice.
+			 * Temporarily increase the refcount to detect this situation. */
+			GC_TRY_ADDREF(ht);
+
+			zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+
+			if (!(GC_FLAGS(ht) & IS_ARRAY_IMMUTABLE) && !GC_DELREF(ht)) {
+				zend_array_destroy(ht);
+				return IS_NULL;
+			}
+
+			if (EG(exception)) {
+				return IS_NULL;
+			}
+
 			value->str = ZSTR_EMPTY_ALLOC();
 			return IS_STRING;
 		case IS_DOUBLE:
@@ -2699,6 +2714,21 @@ static zend_never_inline uint8_t slow_index_convert_w(HashTable *ht, const zval
 			ZEND_FALLTHROUGH;
 		}
 		case IS_NULL:
+			/* The array may be destroyed while throwing the notice.
+			 * Temporarily increase the refcount to detect this situation. */
+			GC_TRY_ADDREF(ht);
+
+			zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+
+			if (!(GC_FLAGS(ht) & IS_ARRAY_IMMUTABLE) && GC_DELREF(ht) != 1) {
+				if (!GC_REFCOUNT(ht)) {
+					zend_array_destroy(ht);
+				}
+				return IS_NULL;
+			}
+			if (EG(exception)) {
+				return IS_NULL;
+			}
 			value->str = ZSTR_EMPTY_ALLOC();
 			return IS_STRING;
 		case IS_DOUBLE:
@@ -3192,7 +3222,22 @@ static zend_never_inline zval* ZEND_FASTCALL zend_find_array_dim_slow(HashTable
 num_idx:
 		return zend_hash_index_find(ht, hval);
 	} else if (Z_TYPE_P(offset) == IS_NULL) {
-str_idx:
+null_undef_idx:
+		/* The array may be destroyed while throwing the notice.
+		 * Temporarily increase the refcount to detect this situation. */
+		GC_TRY_ADDREF(ht);
+
+		zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+
+		if (!(GC_FLAGS(ht) & IS_ARRAY_IMMUTABLE) && !GC_DELREF(ht)) {
+			zend_array_destroy(ht);
+			return NULL;
+		}
+
+		if (EG(exception)) {
+			return NULL;
+		}
+
 		return zend_hash_find_known_hash(ht, ZSTR_EMPTY_ALLOC());
 	} else if (Z_TYPE_P(offset) == IS_FALSE) {
 		hval = 0;
@@ -3206,7 +3251,7 @@ str_idx:
 		goto num_idx;
 	} else if (/*OP2_TYPE == IS_CV &&*/ Z_TYPE_P(offset) == IS_UNDEF) {
 		ZVAL_UNDEFINED_OP2();
-		goto str_idx;
+		goto null_undef_idx;
 	} else {
 		zend_illegal_array_offset_isset(offset);
 		return NULL;
@@ -3327,6 +3372,9 @@ num_key:
 	} else if (Z_TYPE_P(key) <= IS_NULL) {
 		if (UNEXPECTED(Z_TYPE_P(key) == IS_UNDEF)) {
 			ZVAL_UNDEFINED_OP1();
+		} else {
+			ZEND_ASSERT(Z_TYPE_P(key) == IS_NULL);
+			zend_error(E_DEPRECATED, "Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead");
 		}
 		str = ZSTR_EMPTY_ALLOC();
 		goto str_key;

ext/opcache/jit/zend_jit_helpers.c

@@ -501,8 +501,17 @@ static void ZEND_FASTCALL zend_jit_fetch_dim_r_helper(zend_array *ht, zval *dim,
 			}
 			ZEND_FALLTHROUGH;
 		case IS_NULL:
-			offset_key = ZSTR_EMPTY_ALLOC();
-			goto str_index;
+			retval = zend_hash_find(ht, ZSTR_EMPTY_ALLOC());
+			if (!retval) {
+				ZVAL_NULL(result);
+			} else {
+				ZVAL_COPY_DEREF(result, retval);
+			}
+			zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+			if (!retval) {
+				zend_error(E_WARNING, "Undefined array key \"\"");
+			}
+			return;
 		case IS_DOUBLE:
 			hval = zend_dval_to_lval(Z_DVAL_P(dim));
 			if (!zend_is_long_compatible(Z_DVAL_P(dim), hval)) {
@@ -643,8 +652,16 @@ static void ZEND_FASTCALL zend_jit_fetch_dim_is_helper(zend_array *ht, zval *dim
 			}
 			ZEND_FALLTHROUGH;
 		case IS_NULL:
-			offset_key = ZSTR_EMPTY_ALLOC();
-			goto str_index;
+			retval = zend_hash_find(ht, ZSTR_EMPTY_ALLOC());
+			if (!retval) {
+				ZVAL_NULL(result);
+			} else {
+				ZVAL_COPY_DEREF(result, retval);
+			}
+
+			zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+
+			return;
 		case IS_DOUBLE:
 			hval = zend_dval_to_lval(Z_DVAL_P(dim));
 			if (!zend_is_long_compatible(Z_DVAL_P(dim), hval)) {
@@ -770,9 +787,17 @@ static int ZEND_FASTCALL zend_jit_fetch_dim_isset_helper(zend_array *ht, zval *d
 				return 0;
 			}
 			ZEND_FALLTHROUGH;
-		case IS_NULL:
-			offset_key = ZSTR_EMPTY_ALLOC();
-			goto str_index;
+		case IS_NULL: {
+			int result = 0;
+			retval = zend_hash_find(ht, ZSTR_EMPTY_ALLOC());
+			if (retval) {
+				result = Z_TYPE_P(retval) > IS_NULL;
+			}
+
+			zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+
+			return result;
+		}
 		case IS_DOUBLE:
 			hval = zend_dval_to_lval(Z_DVAL_P(dim));
 			if (!zend_is_long_compatible(Z_DVAL_P(dim), hval)) {
@@ -879,6 +904,32 @@ static zval* ZEND_FASTCALL zend_jit_fetch_dim_rw_helper(zend_array *ht, zval *di
 			}
 			ZEND_FALLTHROUGH;
 		case IS_NULL:
+			/* The array may be destroyed while throwing the notice.
+			 * Temporarily increase the refcount to detect this situation. */
+			GC_TRY_ADDREF(ht);
+
+			execute_data = EG(current_execute_data);
+			opline = EX(opline);
+			zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+			if (!(GC_FLAGS(ht) & IS_ARRAY_IMMUTABLE) && GC_DELREF(ht) != 1) {
+				if (!GC_REFCOUNT(ht)) {
+					zend_array_destroy(ht);
+				}
+				if (opline->result_type & (IS_VAR | IS_TMP_VAR)) {
+					if (EG(exception)) {
+						ZVAL_UNDEF(EX_VAR(opline->result.var));
+					} else {
+						ZVAL_NULL(EX_VAR(opline->result.var));
+					}
+				}
+				return NULL;
+			}
+			if (EG(exception)) {
+				if (opline->result_type & (IS_VAR | IS_TMP_VAR)) {
+					ZVAL_UNDEF(EX_VAR(opline->result.var));
+				}
+				return NULL;
+			}
 			offset_key = ZSTR_EMPTY_ALLOC();
 			goto str_index;
 		case IS_DOUBLE:
@@ -1012,6 +1063,36 @@ static zval* ZEND_FASTCALL zend_jit_fetch_dim_w_helper(zend_array *ht, zval *dim
 			}
 			ZEND_FALLTHROUGH;
 		case IS_NULL:
+			/* The array may be destroyed while throwing the notice.
+			 * Temporarily increase the refcount to detect this situation. */
+			GC_TRY_ADDREF(ht);
+
+			execute_data = EG(current_execute_data);
+			opline = EX(opline);
+			zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+			if (!(GC_FLAGS(ht) & IS_ARRAY_IMMUTABLE) && GC_DELREF(ht) != 1) {
+				if (!GC_REFCOUNT(ht)) {
+					zend_array_destroy(ht);
+				}
+				if (opline->result_type & (IS_VAR | IS_TMP_VAR)) {
+					if (EG(exception)) {
+						ZVAL_UNDEF(EX_VAR(opline->result.var));
+					} else {
+						ZVAL_NULL(EX_VAR(opline->result.var));
+					}
+				}
+				if (opline->opcode == ZEND_ASSIGN_DIM
+				 && ((opline+1)->op1_type & (IS_VAR | IS_TMP_VAR))) {
+					zval_ptr_dtor_nogc(EX_VAR((opline+1)->op1.var));
+				}
+				return NULL;
+			}
+			if (EG(exception)) {
+				if (opline->result_type & (IS_VAR | IS_TMP_VAR)) {
+					ZVAL_UNDEF(EX_VAR(opline->result.var));
+				}
+				return NULL;
+			}
 			offset_key = ZSTR_EMPTY_ALLOC();
 			goto str_index;
 		case IS_DOUBLE:

ext/opcache/tests/jit/copy_tmp_001.phpt

@@ -15,7 +15,10 @@ $a = [];
 $a[test()] ??= 1;
 var_dump($a);
 ?>
---EXPECT--
+--EXPECTF--
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 array(1) {
   [""]=>
   int(1)

ext/opcache/tests/jit/fetch_dim_r_002.phpt

@@ -30,7 +30,7 @@ $x=2;
 $y="x";
 foo($x.$y);
 ?>
---EXPECT--
+--EXPECTF--
 int(1)
 int(3)
 int(2)
@@ -38,6 +38,8 @@ int(1)
 int(3)
 int(1)
 int(2)
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 int(4)
 int(5)
 int(5)

ext/spl/spl_array.c

@@ -280,6 +280,7 @@ static zend_result get_hash_key(spl_hash_key *key, spl_array_object *intern, zva
 try_again:
 	switch (Z_TYPE_P(offset)) {
 	case IS_NULL:
+		zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
 		key->key = ZSTR_EMPTY_ALLOC();
 		return SUCCESS;
 	case IS_STRING:

ext/spl/tests/bug62978.phpt

@@ -26,6 +26,8 @@ var_dump($a[$fp]);
 fclose($fp);
 ?>
 --EXPECTF--
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
 Warning: Undefined array key "epic_magic" in %s on line %d
 NULL
 

ext/spl/tests/bug70852.phpt

@@ -8,8 +8,12 @@ var_dump($y[NULL]);
 var_dump($y[NULL]++);
 ?>
 --EXPECTF--
-Warning: Undefined array key "" in %s on line %d
-NULL
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Warning: Undefined array key "" in %s on line %d
+NULL
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 
 Warning: Undefined array key "" in %s on line %d
 NULL

ext/standard/array.c

@@ -6981,6 +6981,7 @@ PHP_FUNCTION(array_key_exists)
 			RETVAL_BOOL(zend_hash_index_exists(ht, Z_LVAL_P(key)));
 			break;
 		case IS_NULL:
+			zend_error(E_DEPRECATED, "Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead");
 			RETVAL_BOOL(zend_hash_exists(ht, ZSTR_EMPTY_ALLOC()));
 			break;
 		case IS_DOUBLE:

ext/standard/tests/array/array_key_exists.phpt

@@ -82,7 +82,7 @@ try {
 
 echo "Done\n";
 ?>
---EXPECT--
+--EXPECTF--
 *** Testing basic functionalities ***
 -- Iteration 1 --
 bool(true)
@@ -104,7 +104,11 @@ bool(true)
 ** Variation loop 1 **
 -- Iteration 1 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -112,7 +116,11 @@ bool(false)
 bool(true)
 -- Iteration 2 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -120,7 +128,11 @@ bool(false)
 bool(true)
 -- Iteration 3 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -128,7 +140,11 @@ bool(false)
 bool(true)
 -- Iteration 4 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -136,7 +152,11 @@ bool(false)
 bool(true)
 -- Iteration 5 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -144,7 +164,11 @@ bool(false)
 bool(false)
 -- Iteration 6 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -152,7 +176,11 @@ bool(false)
 bool(false)
 -- Iteration 7 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -162,7 +190,11 @@ bool(true)
 ** Variation loop 2 **
 -- Iteration 1 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -170,7 +202,11 @@ bool(false)
 bool(false)
 -- Iteration 2 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -178,7 +214,11 @@ bool(false)
 bool(false)
 -- Iteration 3 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)
@@ -186,7 +226,11 @@ bool(false)
 bool(true)
 -- Iteration 4 --
 bool(true)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(true)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(true)
 bool(false)
 bool(true)
@@ -194,7 +238,11 @@ bool(false)
 bool(true)
 -- Iteration 5 --
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 bool(false)
 bool(false)

ext/standard/tests/array/array_key_exists_variation1.phpt

@@ -105,9 +105,13 @@ bool(false)
 bool(false)
 
 -- Iteration 5 --
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 -- Iteration 6 --
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 -- Iteration 7 --
@@ -144,9 +148,13 @@ bool(true)
 Cannot access offset of type classA on array
 
 -- Iteration 18 --
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 -- Iteration 19 --
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(false)
 
 -- Iteration 20 --

ext/standard/tests/array/array_key_exists_variation6.phpt

@@ -36,54 +36,110 @@ foreach($array as $name => $input) {
 
 echo "Done";
 ?>
---EXPECT--
+--EXPECTF--
 *** Testing array_key_exists() : usage variations ***
 
 -- Key in $search array is : null --
-Iteration 1:  bool(true)
-Iteration 2:  bool(true)
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Iteration 1:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 2:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 Iteration 3:  bool(true)
 Iteration 4:  bool(true)
-Iteration 5:  bool(true)
-Iteration 6:  bool(true)
+Iteration 5:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 6:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 
 -- Key in $search array is : NULL --
-Iteration 1:  bool(true)
-Iteration 2:  bool(true)
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Iteration 1:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 2:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 Iteration 3:  bool(true)
 Iteration 4:  bool(true)
-Iteration 5:  bool(true)
-Iteration 6:  bool(true)
+Iteration 5:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 6:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 
 -- Key in $search array is : empty single quoted string --
-Iteration 1:  bool(true)
-Iteration 2:  bool(true)
+Iteration 1:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 2:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 Iteration 3:  bool(true)
 Iteration 4:  bool(true)
-Iteration 5:  bool(true)
-Iteration 6:  bool(true)
+Iteration 5:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 6:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 
 -- Key in $search array is : empty double quoted string --
-Iteration 1:  bool(true)
-Iteration 2:  bool(true)
+Iteration 1:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 2:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 Iteration 3:  bool(true)
 Iteration 4:  bool(true)
-Iteration 5:  bool(true)
-Iteration 6:  bool(true)
+Iteration 5:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 6:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 
 -- Key in $search array is : undefined variable --
-Iteration 1:  bool(true)
-Iteration 2:  bool(true)
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Iteration 1:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 2:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 Iteration 3:  bool(true)
 Iteration 4:  bool(true)
-Iteration 5:  bool(true)
-Iteration 6:  bool(true)
+Iteration 5:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 6:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 
 -- Key in $search array is : unset variable --
-Iteration 1:  bool(true)
-Iteration 2:  bool(true)
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+Iteration 1:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 2:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 Iteration 3:  bool(true)
 Iteration 4:  bool(true)
-Iteration 5:  bool(true)
-Iteration 6:  bool(true)
+Iteration 5:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+Iteration 6:  
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
 Done

ext/standard/tests/array/bug20865.phpt

@@ -7,5 +7,8 @@ Bug #20865 (array_key_exists and NULL key)
 
     var_dump(array_key_exists(NULL, $ta));
 ?>
---EXPECT--
+--EXPECTF--
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
 bool(true)

tests/basic/array_key_exists_null_deprecation.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Deprecate using null as key in array_key_exists()
+--FILE--
+<?php
+$arr = ['foo' => 'bar', '' => 'baz'];
+
+var_dump(array_key_exists(null, $arr));
+var_dump(array_key_exists('', $arr));
+?>
+--EXPECTF--
+Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d
+bool(true)
+bool(true)

tests/basic/array_null_offset_deprecation.phpt

@@ -0,0 +1,27 @@
+--TEST--
+Deprecate using null as array offset
+--FILE--
+<?php
+$arr = ['foo' => 'bar', '' => 'baz'];
+
+echo $arr[null] . "\n";
+
+$arr[null] = 'new_value';
+echo $arr[''] . "\n";
+
+var_dump(isset($arr[null]));
+
+unset($arr[null]);
+var_dump(isset($arr['']));
+?>
+--EXPECTF--
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+baz
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+new_value
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
+bool(true)
+bool(false)