Deprecate passing null to non-nullable arg of internal function

This deprecates passing null to non-nullable scale arguments of
internal functions, with the eventual goal of making the behavior
consistent with userland functions, where null is never accepted
for non-nullable arguments.

This change is expected to cause quite a lot of fallout. In most
cases, calling code should be adjusted to avoid passing null. In
some cases, PHP should be adjusted to make some function arguments
nullable. I have already fixed a number of functions before landing
this, but feel free to file a bug if you encounter a function that
doesn't accept null, but probably should. (The rule of thumb for
this to be applicable is that the function must have special behavior
for 0 or "", which is distinct from the natural behavior of the
parameter.)

RFC: https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg

Closes GH-6475.

Author: nikic

UPGRADING

@@ -27,6 +27,16 @@ PHP 8.1 UPGRADE NOTES
     array is no longer supported. For example, array_pop($GLOBALS) will result
     in an error.
     RFC: https://wiki.php.net/rfc/restrict_globals_usage
+  . Passing null to a non-nullable argument of a built-in function is
+    deprecated. This matches the behavior of user-defined functions, where null
+    is never accepted by non-nullable arguments.
+    user-defined functions.
+
+        var_dump(str_contains("foobar", null));
+        // Deprecated: Passing null to parameter #2 ($needle) of type string
+        //             is deprecated
+
+    RFC: https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg
 
 - Fileinfo:
   . The fileinfo functions now accept and return, respectively, finfo objects

Zend/tests/bug43201.phpt

@@ -30,25 +30,37 @@ Warning: Undefined variable $ref in %s on line %d
 
 Warning: Undefined variable $undef in %s on line %d
 
+Deprecated: chop(): Passing null to parameter #1 ($string) of type string is deprecated in %s on line %d
+
 Notice: Indirect modification of overloaded property Foo::$arr has no effect in %sbug43201.php on line 17
 
 Warning: Undefined variable $undef in %s on line %d
 
+Deprecated: chop(): Passing null to parameter #1 ($string) of type string is deprecated in %s on line %d
+
 Notice: Indirect modification of overloaded property Foo::$arr has no effect in %sbug43201.php on line 17
 
 Warning: Undefined variable $undef in %s on line %d
 
+Deprecated: chop(): Passing null to parameter #1 ($string) of type string is deprecated in %s on line %d
+
 Notice: Indirect modification of overloaded property Foo::$arr has no effect in %sbug43201.php on line 17
 
 Warning: Undefined variable $undef in %s on line %d
 
+Deprecated: chop(): Passing null to parameter #1 ($string) of type string is deprecated in %s on line %d
+
 Notice: Indirect modification of overloaded property Foo::$arr has no effect in %sbug43201.php on line 17
 
 Warning: Undefined variable $undef in %s on line %d
 
+Deprecated: chop(): Passing null to parameter #1 ($string) of type string is deprecated in %s on line %d
+
 Notice: Indirect modification of overloaded property Foo::$arr has no effect in %sbug43201.php on line 17
 
 Warning: Undefined variable $undef in %s on line %d
 
+Deprecated: chop(): Passing null to parameter #1 ($string) of type string is deprecated in %s on line %d
+
 Notice: Indirect modification of overloaded property Foo::$arr has no effect in %sbug43201.php on line 17
 ok

Zend/tests/bug64677.phpt

@@ -7,7 +7,7 @@ class cat {
     }
 }
 $cat = new cat();
-$cat->show_output('Files: ', trim(`cd .`)); // this gives invalid args to shell_exec
+$cat->show_output('Files: ', trim((string) `cd .`)); // this gives invalid args to shell_exec
 $cat->show_output('Files: ', `cd .`); // this causes a segmentation fault
 $cat->show_output(`cd .`); // this causes a segmentation fault
 

Zend/tests/class_exists_002.phpt

@@ -8,15 +8,13 @@ class foo {
 }
 
 var_dump(class_exists(''));
-var_dump(class_exists(NULL));
 var_dump(class_exists('FOO'));
 var_dump(class_exists('bar'));
 var_dump(class_exists(1));
 
 ?>
 --EXPECT--
 bool(false)
-bool(false)
 bool(true)
 bool(false)
 bool(false)

Zend/tests/exception_001.phpt

@@ -7,7 +7,7 @@ try {
     try {
         try {
             try {
-                throw new Exception(NULL);
+                throw new Exception();
             } catch (Exception $e) {
                 var_dump($e->getMessage());
                 throw $e;

Zend/tests/interface_exists_001.phpt

@@ -8,10 +8,8 @@ interface foo {
 
 var_dump(interface_exists('foo'));
 var_dump(interface_exists(1));
-var_dump(interface_exists(NULL));
 
 ?>
 --EXPECT--
 bool(true)
 bool(false)
-bool(false)

Zend/tests/null_to_non_nullable_special_func.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Test null arg behavior for special functions
+--FILE--
+<?php
+
+$null = null;
+var_dump(strlen($null));
+
+?>
+--EXPECTF--
+Deprecated: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in %s on line %d
+int(0)

Zend/tests/nullsafe_operator/013.phpt

@@ -38,14 +38,21 @@ dump_error(fn() => array_key_exists('foo', $foo?->foo()));
 
 ?>
 --EXPECTF--
+Deprecated: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in %s on line %d
 int(0)
 bool(true)
 bool(false)
 bool(false)
 bool(false)
 bool(false)
+
+Deprecated: defined(): Passing null to parameter #1 ($constant_name) of type string is deprecated in %s on line %d
 bool(false)
+
+Deprecated: chr(): Passing null to parameter #1 ($codepoint) of type int is deprecated in %s on line %d
 string(1) "%s"
+
+Deprecated: ord(): Passing null to parameter #1 ($character) of type string is deprecated in %s on line %d
 int(0)
 string(98) "call_user_func_array(): Argument #1 ($function) must be a valid callback, no array or string given"
 string(77) "call_user_func_array(): Argument #2 ($args) must be of type array, null given"
@@ -55,6 +62,8 @@ string(4) "NULL"
 string(52) "func_num_args() expects exactly 0 arguments, 1 given"
 string(52) "func_get_args() expects exactly 0 arguments, 1 given"
 string(69) "array_slice(): Argument #1 ($array) must be of type array, null given"
+
+Deprecated: array_slice(): Passing null to parameter #2 ($offset) of type int is deprecated in %s on line %d
 array(1) {
   [0]=>
   string(3) "foo"

Zend/tests/str_or_obj_of_class_zpp.phpt

@@ -51,9 +51,11 @@ try {
 }
 
 ?>
---EXPECT--
+--EXPECTF--
 string(6) "string"
 string(1) "1"
+
+Deprecated: zend_string_or_stdclass(): Passing null to parameter #1 ($param) of type string is deprecated in %s on line %d
 string(0) ""
 object(stdClass)#1 (0) {
 }

Zend/tests/str_or_obj_zpp.phpt

@@ -34,9 +34,11 @@ try {
 }
 
 ?>
---EXPECT--
+--EXPECTF--
 string(6) "string"
 string(1) "1"
+
+Deprecated: zend_string_or_object(): Passing null to parameter #1 ($param) of type object|string is deprecated in %s on line %d
 string(0) ""
 object(stdClass)#1 (0) {
 }

Zend/tests/trait_exists_001.phpt

@@ -8,10 +8,8 @@ trait foo {
 
 var_dump(trait_exists('foo'));
 var_dump(trait_exists(1));
-var_dump(trait_exists(NULL));
 
 ?>
 --EXPECT--
 bool(true)
 bool(false)
-bool(false)