The document outlines the tentative release schedule for PHP 8.0, including key features like the just-in-time (JIT) compiler and updates to attributes usage. It discusses enhancements such as union and mixed types, constructor promotion, and the migration of resources to objects, along with significant backwards compatibility breaks. Additionally, it highlights changes in error handling and the introduction of PHP stubs for internal functions.

4. Release schedule (tentative)
June 18th PHP 8.0 Alpha 1
July 28th PHP 8.0 Feature freeze
December 3rd PHP 8.0 Release

6. Just-In-Time (JIT) Compiler
●
Compiles PHP code to x86 machine code
●
Performance improvements mostly apply to
math heavy code

7. Just-In-Time (JIT) Compiler
●
Compiles PHP code to x86 machine code
●
Performance improvements mostly apply to
math heavy code
●
Part of opcache:
– opcache.jit=on
– opcache.jit_buffer_size=128M

8. Attributes
<?php
/** @Entity */
class User {
/**
* @Id
* @Column(type="integer")
* @GeneratedValue
*/
private $id;
}

9. Attributes
<?php
use DoctrineORMAttributes as ORM;
<<ORMEntity>>
class User {
<<ORMId>>
<<ORMColumn("integer")>>
<<ORMGeneratedValue>>
private $id;
}

10. Attributes
<?php
use DoctrineORMAttributes as ORM;
<<ORMEntity>>
class User {
<<ORMId>>
<<ORMColumn("integer")>>
<<ORMGeneratedValue>>
private $id;
}
Class name
Constructor arguments

11. Attributes
<?php
namespace DoctrineORMAttributes;
use PhpAttribute;
<<PhpAttribute>>
class Column {
public function __construct(string $type) { … }
}

12. Attributes
<?php
$rc = new ReflectionClass(User::class);
foreach ($rc->getAttributes() as $attr) {
var_dump($attr->getName());
// => "DoctrineORMAttributesEntity"
var_dump($attr->getArguments());
// => []
var_dump($attr->newInstance());
// object(DoctrineORMAttributesEntity) ...
}

13. Attributes
<?php
$rc = new ReflectionClass(User::class);
foreach ($rc->getAttributes() as $attr) {
var_dump($attr->getName());
// => "DoctrineORMAttributesEntity"
var_dump($attr->getArguments());
// => []
var_dump($attr->newInstance());
// object(DoctrineORMAttributesEntity) ...
}
Attribute validation happens HERE.

14. Attributes: Limitations
●
No named parameters:
– @Column(type="string", unique=true)
– <<Column("string", ['unique' => true])>>

15. Attributes: Limitations
●
No named parameters:
– @Column(type="string", unique=true)
– <<Column("string", ['unique' => true])>>
●
No nested attributes:
– @AssertAll({ @AssertNotBlank,
@AssertLength(min=5) })

16. Attributes: Limitations
●
No named parameters:
– @Column(type="string", unique=true)
– <<Column("string", ['unique' => true])>>
●
No nested attributes:
– @AssertAll({ @AssertNotBlank,
@AssertLength(min=5) })
"new" currently not supported in constant expressions

17. Attributes: Use-Cases
●
Replaces phpdoc annotations in Doctrine,
Symfony, etc…
●
May add internal attributes:
– <<Deprecated("Use xyz instead")>>
– <<Jit>>, <<NoJit>>

18. Union Types
●
Existing union types:
– ?Type = Type|null
– iterable = Traversable|array

19. Union Types
<?php
class Number {
/** @var int|float $number */
private $number;
/** @param int|float $number */
public function setNumber($number) {
$this->number = $number;
}
/** @return int|float */
public function getNumber() {
return $this->number;
}
}

20. Union Types
<?php
class Number {
private int|float $number;
public function setNumber(int|float $number) {
$this->number = $number;
}
public function getNumber(): int|float {
return $this->number;
}
}

21. Union Types
<?php
function strpos(
string $haystack, string $needle, int $offset = 0
): int|false {}

22. Union Types
<?php
function strpos(
string $haystack, string $needle, int $offset = 0
): int|false {}
Very common in standard library

23. Union Types
<?php
function strpos(
string $haystack, string $needle, int $offset = 0
): int|false {}
function array_key_first(array $arg): int|string|null {}
?Type is a shorthand for Type|null now

24. Union Types
●
Tricky interaction with "weak types"
●
Type must be part of union, or...
●
Scalars are coerced to int, float, string, bool, in
order of preference

25. Union Types
<?php declare(strict_types=0);
function test(int|float|bool $arg) {
var_dump($arg);
}
test(45); // int(45)
test(45.8); // float(45.8)
test("45"); // int(45)
test("45.8"); // float(45.8)
test(""); // bool(false)
test("X"); // bool(true)
test([]); // TypeError

26. Union Types
<?php declare(strict_types=1);
function test(int|float|bool $arg) {
var_dump($arg);
}
test(45); // int(45)
test(45.8); // float(45.8)
test("45"); // TypeError
test("45.8"); // TypeError
test(""); // TypeError
test("X"); // TypeError
test([]); // TypeError

27. Mixed Type
●
Distinguishes between:
– Type is missing because I didn't add one yet
– This function really does accept any value

28. Mixed Type
<?php
function var_dump(mixed $value, mixed ...$value): void {}
function serialize(mixed $value): string {}

29. Mixed Type
<?php
// Mixed is a common approximation for generic functions:
function array_reduce<K, V, R>(
array<K, V> $arg,
callable(R, V): R $callback, R $initial = null
): R {}

30. Mixed Type
<?php
// Mixed is a common approximation for generic functions:
function array_reduce<K, V, R>(
array<K, V> $arg,
callable(R, V): R $callback, R $initial = null
): R {}
// Back down to earth:
function array_reduce(
array $arg, callable $callback,
mixed $initial = null
): mixed {}

31. Mixed Type
<?php
// For argument types:
// No type same as mixed type
class A {
public function method(mixed $arg) {}
}
class B extends A {
public function method($arg) {}
}
Allowed

32. Mixed Type
<?php
// For return types:
// No type effectively means mixed|void
class A {
public function method(): mixed {}
}
class B extends A {
public function method() {}
}

33. Mixed Type
<?php
// For return types:
// No type effectively means mixed|void
class A {
public function method(): mixed {}
}
class B extends A {
public function method() {}
}
Forbidden: Widening return type

34. Static Return Type
<?php
// Named constructor:
class TestParent {
public function createFromWhatever($whatever): static {
return new static($whatever);
}
}

35. Static Return Type
<?php
// Named constructor:
class TestParent {
public function createFromWhatever($whatever): static {
return new static($whatever);
}
}
class TestChild extends TestParent {}
// TestChild::createFromWhatever(…)
// must return TestChild, not TestParent!

36. Static Return Type
<?php
// Wither pattern:
class Test {
public function withWhatever($whatever): static {
$clone = clone $this;
$clone->whatever = $whatever;
return $clone;
}
}

37. Static Return Type
<?php
// Fluent methods:
class Test {
public function doWhatever(): static {
// Do whatever.
return $this;
}
}

38. Constructor Promotion
<?php
class Point {
public float $x;
public float $y;
public float $z;
public function __construct(
float $x = 0.0,
float $y = 0.0,
float $z = 0.0,
) {
$this->x = $x;
$this->y = $y;
$this->z = $z;
}
}

39. Constructor Promotion
<?php
class Point {
public function __construct(
public float $x = 0.0,
public float $y = 0.0,
public float $z = 0.0,
) {}
}

40. Constructor Promotion
<?php
class Point {
public function __construct(
public float $x = 0.0,
public float $y = 0.0,
public float $z = 0.0,
) {}
}
Trailing comma in parameters lists
now allowed

41. str_contains etc.
<?php
function str_contains(
string $haystack, string $needle
): bool {
return false !== strpos($haystack, $needle);
}

42. str_contains etc.
<?php
function str_contains(
string $haystack, string $needle
): bool {}
function str_starts_with(
string $haystack, string $needle
): bool {}
function str_ends_with(
string $haystack, string $needle
): bool {}

43. str_contains etc.
●
No multibyte variants
●
All of these functions are safe to use on UTF-8!
(If you don't use UTF-8, that's your problem)

44. WeakMap
<?php
$map = new WeakMap;
$obj = new stdClass;
$map[$obj] = $dataForObj;
unset($obj); // $obj automatically dropped from WeakMap!

45. WeakMap
<?php
class FooBar {
private WeakMap $cache;
public function getSomethingWithCaching(object $obj) {
return $this->cache[$obj]
??= $this->computeSomethingExpensive($obj);
}
}

46. Backwards Compatibility Breaks
●
Everything deprecated before PHP 8.0 has
been removed!
●
Full list:
https://github.com/php/php-src/blob/master/UPGRADING

47. Resource To Object Migration
●
Long term goal: Convert all resources to objects
●
Objects are type-safe and have much better
internal support

48. Resource To Object Migration
●
Long term goal: Convert all resources to objects
●
Objects are type-safe and have much better
internal support
(This is why we do not support a "resource"
type.)

49. Resource To Object Migration
●
Usually based on "opaque objects"
●
Actual object-oriented APIs may be added later

50. Resource To Object Migration
●
Migrated in previous versions
– EnchantBroker, EnchantDictionary
– GdImage
– SysvMessageQueue
– SysvSemaphore
– XmlParser
– XmlWriter (already had an OO API)
– … more are in progress

51. Resource To Object Migration
<?php
$image = imagecreatefrompng($path);
if (!is_resource($image)) {
throw new MalformedImageException;
}

52. Resource To Object Migration
<?php
$image = imagecreatefrompng($path);
if (!is_resource($image)) {
throw new MalformedImageException;
}
Now a GdImage object on success
We'll always throw...

53. Resource To Object Migration
<?php
$image = imagecreatefrompng($path);
if (false === $image) {
throw new MalformedImageException;
}

54. Warning → Error exception
●
Many warnings converted to Error exceptions
– TypeError
– ValueError

55. Warning → Error exception
●
Only allowed for error conditions that imply
programmer error
●
It makes no sense to "handle" the error, code
needs to be fixed instead

56. Warning → Error exception
<?php
var_dump(strlen([]));
// Warning: strlen() expects parameter 1 to be string,
// array given
// NULL
function strlen(string $str): int|null {}

57. Warning → Error exception
<?php
var_dump(strlen([]));
// Uncaught TypeError: strlen(): Argument #1 ($str)
// must be of type string, array given
function strlen(string $str): int {}

58. Warning → Error exception
<?php
var_dump(array_fill(0, -100, "foobar"));
// Warning: array_fill(): Number of elements can't
// be negative
// bool(false)
function array_fill(
int $start_index, int $num, mixed $value
): array|false {}

59. Warning → Error exception
<?php
var_dump(array_fill(0, -100, "foobar"));
// Uncaught ValueError: array_fill(): Argument #2 ($num)
// must be greater than or equal to 0
function array_fill(
int $start_index, int $num, mixed $value
): array {}

60. Warning → Error exception
<?php
var_dump(fopen("does_not_exist.txt", "r"));
// Warning: fopen(does_not_exist.txt):
// Failed to open stream: No such file or directory
// bool(false)

61. Warning → Error exception
<?php
var_dump(fopen("does_not_exist.txt", "r"));
// Warning: fopen(does_not_exist.txt):
// Failed to open stream: No such file or directory
// bool(false)
NOT going to change!
fopen() failure is an environment failure condition,
it does not imply programmer error!

62. PHP Stubs
●
PHP stub files specify function signatures for
internal functions/methods
●
Used to generate C code for function
registration

63. PHP Stubs
<?php
function array_search(
mixed $needle, array $haystack, bool $strict = false
): int|string|false {}

64. PHP Stubs
<?php
function array_search(
mixed $needle, array $haystack, bool $strict = false
): int|string|false {}
ZEND_BEGIN_ARG_WITH_RETURN_TYPE_MASK_EX(
arginfo_array_search, 0, 2,
MAY_BE_LONG|MAY_BE_STRING|MAY_BE_FALSE)
ZEND_ARG_TYPE_INFO(0, needle, IS_MIXED, 0)
ZEND_ARG_TYPE_INFO(0, haystack, IS_ARRAY, 0)
ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(
0, strict, _IS_BOOL, 0, "false")
ZEND_END_ARG_INFO()

65. PHP Stubs
●
Data available through Reflection:
– ReflectionFunction::getReturnType()
– ReflectionParameter::getType()
– ReflectionParameter::getDefaultValue()

66. PHP Stubs
<?php
// Stub
class DateTime implements DateTimeInterface {
/** @return DateTime */
public function add(DateInterval $interval) {}
}
// Your code
class MyDateTime extends DateTime {
public function add(DateInterval $interval) {
// Do something
}
}

67. PHP Stubs
<?php
// Stub
class DateTime implements DateTimeInterface {
/** @return DateTime */
public function add(DateInterval $interval) {}
}
// Your code
class MyDateTime extends DateTime {
public function add(DateInterval $interval) {
// Do something
}
}
Now allowed!

68. PHP Stubs
<?php
// Stub
class DateTime implements DateTimeInterface {
/** @return DateTime */
public function add(DateInterval $interval) {}
}
// Your code
class MyDateTime extends DateTime {
public function add(DateInterval $interval) {
// Do something
}
}
Now allowed!
A real return type would force all extending
classes to specify it.

70. 3v4l.org

71. Travis CI
php:
- nightly
install:
- |
if [ $TRAVIS_PHP_VERSION = 'nightly' ]; then
composer install --ignore-platform-reqs;
else
composer install;
fi
Many libraries are not formally
compatible with PHP 8 (yet)

72. Docker
●
https://github.com/devilbox/docker-php-fpm-8.0

73. Thank You!