Implement typed properties

RFC: https://wiki.php.net/rfc/typed_properties_v2

This is a squash of PR #3734, which is a squash of PR #3313.

Co-authored-by: Bob Weinand <bobwei9@hotmail.com>
Co-authored-by: Joe Watkins <krakjoe@php.net>
Co-authored-by: Dmitry Stogov <dmitry@zend.com>

UPGRADING

@@ -78,8 +78,20 @@ PHP 7.4 UPGRADE NOTES
 2. New Features
 ========================================
 
+- Core:
+  . Added support for typed properties. For example:
+
+        class User {
+            public int $id;
+            public string $name;
+        }
+
+    This will enforce that $user->id can only be assigned integer and
+    $user->name can only be assigned strings. For more information see the
+    RFC: https://wiki.php.net/rfc/typed_properties_v2
+
 - PDO_OCI:
-  . PDOStatement::getColumnMeta is now available
+  . PDOStatement::getColumnMeta() is now available
 
 - PDO_SQLite:
   . PDOStatement::getAttribute(PDO::SQLITE_ATTR_READONLY_STATEMENT) allows to

UPGRADING.INTERNALS

@@ -13,6 +13,8 @@ PHP 7.4 INTERNALS UPGRADE NOTES
   j. Removed add_get_assoc_*() and add_get_index_*()
   k. Class declaration opcodes
   l. HASH_FLAG_INITIALIZED
+  m. write_property return value
+  n. Assignments to references
 
 2. Build system changes
   a. Abstract
@@ -158,6 +160,17 @@ PHP 7.4 INTERNALS UPGRADE NOTES
      Special HT_IS_INITIALIZED() and HT_INVALIDATE() macro were introduced
      to hide implementation details.
 
+  m. The write_property() object handler now returns the assigned value (after
+     possible type coercions) rather than void. For extensions, it should
+     usually be sufficient to return whatever was passed as the argument.
+
+  n. Assignments to references now need to ensure that they respect property
+     types that affect the reference. This means that references should no
+     longer be directly assigned to, and instead a set of specialized macros
+     of the form ZEND_TRY_ASSIGN* needs to be used. You can find detailed
+     porting instructions as well as a compatibility shim in the wiki:
+     https://wiki.php.net/rfc/typed_properties_v2#assignments_to_references
+
 ========================
 2. Build system changes
 ========================

Zend/tests/type_declarations/typed_properties_001.phpt

@@ -0,0 +1,44 @@
+--TEST--
+Test typed properties basic operation
+--FILE--
+<?php
+var_dump(new class(1, 2.2, true, ["four"], new stdClass) {
+	public int $int;
+	public float $float;
+	public bool $bool;
+	public array $array;
+	public stdClass $std;
+	public iterable $it;
+
+	public function __construct(int $int, float $float, bool $bool, array $array, stdClass $std) {
+		$this->int = $int;
+		$this->float = $float;
+		$this->bool = $bool;
+		$this->array = $array;
+		$this->std = $std;
+		$this->it = $array;
+	}
+});
+?>
+--EXPECTF--
+object(class@anonymous)#%d (6) {
+  ["int"]=>
+  int(1)
+  ["float"]=>
+  float(2.2)
+  ["bool"]=>
+  bool(true)
+  ["array"]=>
+  array(1) {
+    [0]=>
+    string(4) "four"
+  }
+  ["std"]=>
+  object(stdClass)#%d (0) {
+  }
+  ["it"]=>
+  array(1) {
+    [0]=>
+    string(4) "four"
+  }
+}

Zend/tests/type_declarations/typed_properties_002.phpt

@@ -0,0 +1,15 @@
+--TEST--
+Test typed properties error condition (read uninitialized)
+--FILE--
+<?php
+$thing = new class() {
+	public int $int;
+};
+
+var_dump($thing->int);
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Typed property class@anonymous::$int must not be accessed before initialization in %s:6
+Stack trace:
+#0 {main}
+  thrown in %s on line 6

Zend/tests/type_declarations/typed_properties_003.phpt

@@ -0,0 +1,15 @@
+--TEST--
+Test typed properties error condition (fetch uninitialized by reference)
+--FILE--
+<?php
+$thing = new class() {
+	public int $int;
+};
+
+$var = &$thing->int;
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Cannot access uninitialized non-nullable property class@anonymous::$int by reference in %s:%d
+Stack trace:
+#0 {main}
+  thrown in %s on line %d

Zend/tests/type_declarations/typed_properties_004.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Test typed properties error condition (type mismatch)
+--FILE--
+<?php
+new class("PHP 7 is better than you, and it knows it ...") {
+	public int $int;
+
+	public function __construct(string $string) {
+		$this->int = $string;
+	}
+};
+?>
+--EXPECTF--
+Fatal error: Uncaught TypeError: Typed property class@anonymous::$int must be int, string used in %s:6
+Stack trace:
+#0 %s(2): class@anonymous->__construct('PHP 7 is better...')
+#1 {main}
+  thrown in %s on line 6

Zend/tests/type_declarations/typed_properties_005.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Test typed properties error condition (type mismatch object)
+--FILE--
+<?php
+class Dummy {}
+
+new class(new Dummy) {
+	public stdClass $std;
+
+	public function __construct(Dummy $dummy) {
+		$this->std = $dummy;
+	}
+};
+?>
+--EXPECTF--
+Fatal error: Uncaught TypeError: Typed property class@anonymous::$std must be an instance of stdClass, Dummy used in %s:8
+Stack trace:
+#0 %s(4): class@anonymous->__construct(Object(Dummy))
+#1 {main}
+  thrown in %s on line 8

Zend/tests/type_declarations/typed_properties_006.phpt

@@ -0,0 +1,14 @@
+--TEST--
+Test typed properties inheritance (scalar)
+--FILE--
+<?php
+class Foo {
+	public int $qux;
+}
+
+class Bar extends Foo {
+	public string $qux;
+}
+?>
+--EXPECTF--
+Fatal error: Type of Bar::$qux must be int (as in class Foo) in %s on line 8

Zend/tests/type_declarations/typed_properties_007.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Test typed properties inheritance
+--FILE--
+<?php
+class Whatever {}
+class Thing extends Whatever {}
+
+class Foo {
+	public Whatever $qux;
+}
+
+class Bar extends Foo {
+	public Thing $qux;
+}
+?>
+--EXPECTF--
+Fatal error: Type of Bar::$qux must be Whatever (as in class Foo) in %s on line 11

Zend/tests/type_declarations/typed_properties_008.phpt

@@ -0,0 +1,14 @@
+--TEST--
+Test typed properties inheritance (missing info)
+--FILE--
+<?php
+class Foo {
+	public int $qux;
+}
+
+class Bar extends Foo {
+	public $qux;
+}
+?>
+--EXPECTF--
+Fatal error: Type of Bar::$qux must be int (as in class Foo) in %s on line 8

Zend/tests/type_declarations/typed_properties_009.phpt

@@ -0,0 +1,23 @@
+--TEST--
+Test typed properties unset leaves properties in an uninitialized state
+--FILE--
+<?php
+class Foo {
+	public int $bar;
+
+	public function __get($name) {
+		var_dump($name);
+		/* return value has to be compatible with int */
+		return 0;
+	}
+}
+
+$foo = new Foo();
+
+unset($foo->bar);
+
+var_dump($foo->bar);
+?>
+--EXPECT--
+string(3) "bar"
+int(0)

Zend/tests/type_declarations/typed_properties_010.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Test typed properties allow fetch reference
+--FILE--
+<?php
+class Foo {
+	public int $bar = 1;
+}
+
+$cb = function(int &$bar) {
+	var_dump($bar);
+};
+
+$foo = new Foo();
+$cb($foo->bar);
+?>
+--EXPECT--
+int(1)

Zend/tests/type_declarations/typed_properties_011.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Test typed properties allow fetch reference for init array
+--FILE--
+<?php
+class Foo {
+	public int $bar = 1;
+}
+
+$foo = new Foo();
+
+$array = [&$foo->bar];
+var_dump($array);
+?>
+--EXPECT--
+array(1) {
+  [0]=>
+  &int(1)
+}

Zend/tests/type_declarations/typed_properties_012.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Test typed properties allow fetch reference for foreach
+--FILE--
+<?php
+class Foo {
+	public int $bar = 1;
+}
+
+$foo = new Foo();
+foreach ($foo as &$prop) {
+	$prop++;
+}
+var_dump($foo);
+?>
+--EXPECT--
+object(Foo)#1 (1) {
+  ["bar"]=>
+  &int(2)
+}

Zend/tests/type_declarations/typed_properties_013.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Test typed properties disallow incorrect type initial value (scalar)
+--FILE--
+<?php
+class Foo {
+	public int $bar = "string";
+}
+?>
+--EXPECTF--
+Fatal error: Default value for property of type int can only be int in %s on line 3

Zend/tests/type_declarations/typed_properties_014.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Test typed properties disallow incorrect type initial value (array)
+--FILE--
+<?php
+class Foo {
+	public array $bar = 32;
+}
+?>
+--EXPECTF--
+Fatal error: Default value for property of type array can only be an array in %s on line 3

Zend/tests/type_declarations/typed_properties_015.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Test typed properties disallow incorrect type initial value (object)
+--FILE--
+<?php
+class Foo {
+	public stdClass $bar = null;
+}
+?>
+--EXPECTF--
+Fatal error: Default value for property of type stdClass may not be null. Use the nullable type ?stdClass to allow null default value in %s on line %d

Zend/tests/type_declarations/typed_properties_016.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Test typed properties initial values
+--FILE--
+<?php
+class Foo {
+	public int $int = 1;
+	public float $flt = 2.2;
+    public float $flt2 = 2;
+	public array $arr = [];
+	public bool $bool = false;
+    public iterable $iter = [];
+}
+echo "ok\n";
+?>
+--EXPECT--
+ok

Zend/tests/type_declarations/typed_properties_017.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Test typed properties disallow void
+--FILE--
+<?php
+class Foo {
+	public void $int;
+}
+
+$foo = new Foo();
+?>
+--EXPECTF--
+Fatal error: Property Foo::$int cannot have type void in %s on line 3

Zend/tests/type_declarations/typed_properties_018.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Test typed properties type applies to all props in group
+--FILE--
+<?php
+class Foo {
+	public int $bar,
+				$qux;
+}
+
+$reflector = new ReflectionClass(Foo::class);
+
+$prop = $reflector->getProperty("qux");
+
+var_dump((string) $prop->getType());
+?>
+--EXPECT--
+string(3) "int"

Zend/tests/type_declarations/typed_properties_019.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Test typed properties int must not be allowed to overflow
+--FILE--
+<?php
+class Foo {
+    public int $bar = PHP_INT_MAX;
+
+    public function inc() {
+        return ++$this->bar;
+    }
+}
+
+$foo = new Foo();
+
+try {
+    $foo->inc();
+} catch (TypeError $e) {
+    echo $e->getMessage(), "\n";
+}
+?>
+--EXPECT--
+Cannot increment property Foo::$bar of type int past its maximal value