[WIP] Implement nullsafe ?-> operator

Zend/tests/nullsafe_operator/001.phpt

@@ -0,0 +1,106 @@
+--TEST--
+Test basic nullsafe method calls
+--FILE--
+<?php
+
+class Foo {
+    function null() {
+        var_dump('Foo::null()');
+        return null;
+    }
+
+    function self() {
+        var_dump('Foo::self()');
+        return $this;
+    }
+}
+
+var_dump(null?->bar());
+var_dump(null?->bar(var_dump('Not executed')));
+var_dump(null?->bar()->baz());
+var_dump(null?->bar()->baz(var_dump('Not executed')));
+var_dump(null?->bar()->baz);
+var_dump(null?->bar()::$baz);
+var_dump(null?->bar()::baz());
+
+$foo = new Foo();
+var_dump($foo->null()?->bar());
+var_dump($foo->null()?->bar(var_dump('Not executed')));
+var_dump($foo->null()?->bar()->baz());
+var_dump($foo->null()?->bar()->baz(var_dump('Not executed')));
+var_dump($foo->null()?->bar()->baz);
+var_dump($foo->null()?->bar()::$baz);
+var_dump($foo->null()?->bar()::baz());
+
+$foo = new Foo();
+var_dump($foo?->self(var_dump('Executed'))->null()?->bar());
+var_dump($foo?->self(var_dump('Executed'))->null()?->bar(var_dump('Not executed')));
+var_dump($foo?->self(var_dump('Executed'))->null()?->bar()->baz());
+var_dump($foo?->self(var_dump('Executed'))->null()?->bar()->baz(var_dump('Not executed')));
+var_dump($foo?->self(var_dump('Executed'))->null()?->bar()->baz);
+var_dump($foo?->self(var_dump('Executed'))->null()?->bar()::$baz);
+var_dump($foo?->self(var_dump('Executed'))->null()?->bar()::baz());
+
+var_dump($foo->self(null?->bar())->null());
+try {
+    var_dump($foo?->self()[null?->bar()]);
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+?>
+--EXPECT--
+NULL
+NULL
+NULL
+NULL
+NULL
+NULL
+NULL
+string(11) "Foo::null()"
+NULL
+string(11) "Foo::null()"
+NULL
+string(11) "Foo::null()"
+NULL
+string(11) "Foo::null()"
+NULL
+string(11) "Foo::null()"
+NULL
+string(11) "Foo::null()"
+NULL
+string(11) "Foo::null()"
+NULL
+string(8) "Executed"
+string(11) "Foo::self()"
+string(11) "Foo::null()"
+NULL
+string(8) "Executed"
+string(11) "Foo::self()"
+string(11) "Foo::null()"
+NULL
+string(8) "Executed"
+string(11) "Foo::self()"
+string(11) "Foo::null()"
+NULL
+string(8) "Executed"
+string(11) "Foo::self()"
+string(11) "Foo::null()"
+NULL
+string(8) "Executed"
+string(11) "Foo::self()"
+string(11) "Foo::null()"
+NULL
+string(8) "Executed"
+string(11) "Foo::self()"
+string(11) "Foo::null()"
+NULL
+string(8) "Executed"
+string(11) "Foo::self()"
+string(11) "Foo::null()"
+NULL
+string(11) "Foo::self()"
+string(11) "Foo::null()"
+NULL
+string(11) "Foo::self()"
+string(38) "Cannot use object of type Foo as array"

Zend/tests/nullsafe_operator/002.phpt

@@ -0,0 +1,42 @@
+--TEST--
+Test nullsafe strict type check
+--FILE--
+<?php
+
+try {
+    false?->bar();
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+try {
+    []?->bar();
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+try {
+    (0)?->bar();
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+try {
+    (0.0)?->bar();
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+try {
+    ''?->bar();
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+?>
+--EXPECT--
+string(39) "Call to a member function bar() on bool"
+string(40) "Call to a member function bar() on array"
+string(38) "Call to a member function bar() on int"
+string(40) "Call to a member function bar() on float"
+string(41) "Call to a member function bar() on string"

Zend/tests/nullsafe_operator/003.phpt

@@ -0,0 +1,66 @@
+--TEST--
+Test basic nullsafe property fetching
+--FILE--
+<?php
+
+class Foo {
+    public $bar = 'bar';
+
+    function qux() {
+        return 'qux';
+    }
+}
+
+$null = null;
+$foo = new Foo();
+
+var_dump(null?->bar);
+var_dump(null?->baz);
+var_dump(null?->qux());
+var_dump(null?->quux());
+
+var_dump((new Foo)?->bar);
+var_dump((new Foo)?->baz);
+var_dump((new Foo)?->qux());
+try {
+    var_dump((new Foo)?->quux());
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+var_dump("{$null?->foo}");
+var_dump("{$null?->bar}");
+var_dump("{$null?->qux()}");
+var_dump("{$null?->quux()}");
+
+var_dump("{$foo?->bar}");
+var_dump("{$foo?->baz}");
+var_dump("{$foo?->qux()}");
+try {
+    var_dump("{$foo?->quux()}");
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+?>
+--EXPECTF--
+NULL
+NULL
+NULL
+NULL
+string(3) "bar"
+
+Warning: Undefined property: Foo::$baz in %s.php on line 20
+NULL
+string(3) "qux"
+string(36) "Call to undefined method Foo::quux()"
+string(0) ""
+string(0) ""
+string(0) ""
+string(0) ""
+string(3) "bar"
+
+Warning: Undefined property: Foo::$baz in %s.php on line 34
+string(0) ""
+string(3) "qux"
+string(36) "Call to undefined method Foo::quux()"

Zend/tests/nullsafe_operator/004.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Test nullsafe property assignment
+--FILE--
+<?php
+
+$foo = null;
+var_dump($foo?->bar = 'bar');
+
+?>
+--EXPECTF--
+Fatal error: Can't use nullsafe operator in write context in %s.php on line 4

Zend/tests/nullsafe_operator/005.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Test nullsafe property assignment op
+--FILE--
+<?php
+
+$foo = null;
+$foo?->bar += 1;
+
+?>
+--EXPECTF--
+Fatal error: Can't use nullsafe operator in write context in %s.php on line 4

Zend/tests/nullsafe_operator/006.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Test nullsafe property post increment
+--FILE--
+<?php
+
+$foo = null;
+++$foo?->bar;
+
+?>
+--EXPECTF--
+Fatal error: Can't use nullsafe operator in write context in %s.php on line 4

Zend/tests/nullsafe_operator/007.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Test nullsafe property pre increment
+--FILE--
+<?php
+
+$foo = null;
+var_dump($foo?->bar++);
+
+?>
+--EXPECTF--
+Fatal error: Can't use nullsafe operator in write context in %s.php on line 4

Zend/tests/nullsafe_operator/008.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Test nullsafe property coalesce assignment
+--FILE--
+<?php
+
+$foo = null;
+var_dump($foo?->bar ??= 'bar');
+
+?>
+--EXPECTF--
+Fatal error: Can't use nullsafe operator in write context in %s.php on line 4

Zend/tests/nullsafe_operator/009.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Test fetch nullsafe property by ref
+--FILE--
+<?php
+
+$foo = null;
+$ref = &$foo?->bar
+
+?>
+--EXPECTF--
+Fatal error: Cannot take reference of a nullsafe chain in %s.php on line 4

Zend/tests/nullsafe_operator/010.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Test fetch nested nullsafe property by ref
+--FILE--
+<?php
+
+$foo = null;
+$ref = &$foo?->bar->baz;
+
+?>
+--EXPECTF--
+Fatal error: Cannot take reference of a nullsafe chain in %s.php on line 4

Zend/tests/nullsafe_operator/011.phpt

@@ -0,0 +1,54 @@
+--TEST--
+Test isset and empty on nullsafe property
+--FILE--
+<?php
+
+class Foo {
+    public $bar;
+}
+
+class Bar {
+    public $baz;
+}
+$bar = new Bar();
+$bar->baz = 'baz';
+
+var_dump(isset($foo?->bar));
+var_dump(empty($foo?->bar));
+
+var_dump(isset($foo?->bar->baz));
+var_dump(empty($foo?->bar->baz));
+echo "\n";
+
+$foo = null;
+var_dump(isset($foo?->bar));
+var_dump(empty($foo?->bar));
+
+var_dump(isset($foo?->bar->baz));
+var_dump(empty($foo?->bar->baz));
+echo "\n";
+
+$foo = new Foo();
+var_dump(isset($foo?->bar->baz));
+var_dump(empty($foo?->bar->baz));
+
+$foo->bar = $bar;
+var_dump(isset($foo?->bar->baz));
+var_dump(empty($foo?->bar->baz));
+
+?>
+--EXPECT--
+bool(false)
+bool(true)
+bool(false)
+bool(true)
+
+bool(false)
+bool(true)
+bool(false)
+bool(true)
+
+bool(false)
+bool(true)
+bool(true)
+bool(false)

Zend/tests/nullsafe_operator/012.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Test nullsafe property on reference
+--FILE--
+<?php
+
+class Foo {
+    public $bar;
+}
+
+$foo = new Foo();
+$foo->bar = 'bar';
+
+$fooRef = &$foo;
+var_dump($fooRef?->bar);
+
+?>
+--EXPECT--
+string(3) "bar"