Add deprecation warning for array API

This is used by array_column(), the AST, and iterators

Author: Girgias

Zend/tests/constexpr/constant_expressions_dynamic.phpt

@@ -48,6 +48,8 @@ var_dump(
 Warning: A non-numeric value encountered in %s on line %d
 
 Deprecated: Implicit conversion from float 3.14 to int loses precision 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(3)
 string(4) "1foo"
 bool(false)

Zend/zend_API.c

@@ -2233,9 +2233,6 @@ ZEND_API zend_result array_set_zval_key(HashTable *ht, zval *key, zval *value) /
 		case IS_STRING:
 			result = zend_symtable_update(ht, Z_STR_P(key), value);
 			break;
-		case IS_NULL:
-			result = zend_hash_update(ht, ZSTR_EMPTY_ALLOC(), value);
-			break;
 		case IS_RESOURCE:
 			zend_use_resource_as_offset(key);
 			result = zend_hash_index_update(ht, Z_RES_HANDLE_P(key), value);
@@ -2252,6 +2249,13 @@ ZEND_API zend_result array_set_zval_key(HashTable *ht, zval *key, zval *value) /
 		case IS_DOUBLE:
 			result = zend_hash_index_update(ht, zend_dval_to_lval_safe(Z_DVAL_P(key)), value);
 			break;
+		case IS_NULL:
+			zend_error(E_DEPRECATED, "Using null as an array offset is deprecated, use an empty string instead");
+			if (UNEXPECTED(EG(exception))) {
+				return FAILURE;
+			}
+			result = zend_hash_update(ht, ZSTR_EMPTY_ALLOC(), value);
+			break;
 		default:
 			zend_illegal_container_offset(ZSTR_KNOWN(ZEND_STR_ARRAY), key, BP_VAR_W);
 			result = NULL;

ext/spl/tests/iterator_to_array_nonscalar_keys.phpt

@@ -21,4 +21,6 @@ try {
 ?>
 --EXPECTF--
 Deprecated: Implicit conversion from float 2.5 to int loses precision in %s on line %d
+
+Deprecated: Using null as an array offset is deprecated, use an empty string instead in %s on line %d
 Cannot access offset of type array on array

ext/standard/tests/array/bug68553.phpt

@@ -37,6 +37,10 @@ try {
 Warning: Resource ID#%d used as offset, casting to integer (%d) in %s on line %d
 
 Deprecated: Implicit conversion from float 7.38 to int loses precision in %s on line %d
+
+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(8) {
   [10]=>
   array(1) {