Description

There seems to be some inconsistent behavior with Disjunctive Normal Form Types when an argument has a default value ofnull.

Usually if the default value isnull, the argument is implicitly nullable, eg:

<?phpfunctionfoo(string$param =null) {var_dump($param); }functionbar(\Foo\Bar|\Foo\Baz$param =null) {var_dump($param); }foo(null);bar(null);

result:

NULLNULL

https://3v4l.org/iBlne

An exception to this rule are PHP 8.1 intersection types:

functionfoo(\Foo\Bar&\Foo\Baz$param =null) {var_dump($param); }foo(null);

result:

Fatal error: Cannot use null as default value for parameter $param of type Foo\Bar&Foo\Baz in /in/k0OjD on line 3Process exited with code 255.

https://3v4l.org/k0OjD

However, the same error is raised on PHP 8.2, even though the following works:

functionfoo((\Foo\Bar&\Foo\Baz)|\Foo\Qux$param =null) {var_dump($param); }foo(null);

result:

NULL

https://3v4l.org/UADDP

With the introduction of DNF types, I would expect\Foo\Bar&\Foo\Baz $param = null to implicitly mean(\Foo\Bar&\Foo\Baz)|null $param = null, which works as expected:

functionfoo((\Foo\Bar&\Foo\Baz)|null$param =null) {var_dump($param); }foo(null);

result:

NULL

https://3v4l.org/gjOAp

PHP Version

PHP 8.2rc3

Operating System

Ubuntu 22.04