Implementation status

The following table gives an overview of the current implementation status. The goal is to have check marks everywhere!

Feature	PHP 7.0	PHP 7.1	PHP 7.2	PHP 7.3	PHP 7.4	PHP 8.0	PHP 8.1	PHP 8.2	PHP 8.3
Future PHP?
• new ... without parentheses	✔	✔	✔	✔	✔	✔	✔	✔	✔
• Typed class constants	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)
• Nullable casting	✔	✔	✔	✔	✔	✔	✔	✔	✔
• Match without expression	✔	✔	✔	✔	✔	✔	✔	✔	✔
• fn with block	✔	✔	✔	✔	✔	✔	✔	✔	✔
Hack
• Using statement / Disposables	✔	✔	✔	✔	✔	✔	✔	✔	✔
• Function types	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)
• Array and map types	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)
PHP 8.3
• Marking overridden methods	✔	✔	✔	✔	✔	✔	✔	✔	native
• Dynamic class constant fetch	✔	✔	✔	✔	✔	✔	✔	✔	native
• Arbitrary static variable initializers	✔	✔	✔	✔	✔	✔	✔	✔	native
PHP 8.2
• True type	✔(6)	✔(6)	✔(6)	✔(6)	✔(6)	✔(6)	✔(6)	native	native
• False type	✔(6)	✔(6)	✔(6)	✔(6)	✔(6)	✔(6)	✔(6)	native	native
• Null type	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	native	native
• Readonly classes	✔	✔	✔	✔	✔	✔	✔	native	native
PHP 8.1
• Array unpacking with string keys	✔	✔	✔	✔	✔	✔	native	native	native
• Readonly properties	✔	✔	✔	✔	✔	✔	native	native	native
• Pure intersection types	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	native	native	native
• First-class callable syntax	✔	✔	✔	✔	✔	✔	native	native	native
• Never return type	✔(5)	✔(5)	✔(5)	✔(5)	✔(5)	✔(5)	native	native	native
• New in initializers	✔(4)	✔(4)	✔(4)	✔(4)	✔(4)	✔(4)	✔(4)	✔(4)	✔(4)
• Enumerations	✔	✔	✔	✔	✔	✔	native	native	native
• Octal integer literal notation	✔	✔	✔	✔	✔	✔	native	native	native
PHP 8.0
• Static return type						native	native	native	native
• Match expression	✔	✔	✔	✔	✔	native	native	native	native
• Named Arguments	✔(3)	✔(3)	✔(3)	✔(3)	✔(3)	native	native	native	native
• Mixed type	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	native	native	native	native
• Attributes / Annotations	✔	✔	✔	✔	✔	✔	✔	✔	✔
• Null-safe instance operator	✔	✔	✔	✔	✔	native	native	native	native
• Constructor argument promotion	✔	✔	✔	✔	✔	native	native	native	native
• Throw expressions	✔	✔	✔	✔	✔	native	native	native	native
• ::class on objects	✔	✔	✔	✔	✔	native	native	native	native
• Union types	✔(1)	✔(1)	✔(1)	✔(1)	✔(1)	native	native	native	native
• Arbitrary expression support for new	✔	✔	✔	✔	✔	native	native	native	native
PHP 7.4
• Spread Operator in Array Expression	✔	✔	✔	✔	native	native	native	native	native
• Numeric Literal Separator	✔	✔	✔	✔	native	native	native	native	native
• Arrow functions	✔	✔	✔	✔	native	native	native	native	native
• Property types	✔(1)	✔(1)	✔(1)	✔(1)	native	native	native	native	native
PHP 7.3
• list() Reference Assignment	✔	✔	✔	native	native	native	native	native	native
• Trailing commas in function calls	✔	✔	✔	native	native	native	native	native	native
PHP 7.2
• Trailing commas in grouped namepaces	✔	✔	native	native	native	native	native	native	native
• Object type	✔(1)	✔(1)	native	native	native	native	native	native	native
PHP 7.1
• Multiple catch	✔	native	native	native	native	native	native	native	native
• Void	✔(1)	native	native	native	native	native	native	native	native
• Iterable	✔(1)	native	native	native	native	native	native	native	native
• Constant modifiers	✔(1)	native	native	native	native	native	native	native	native
• Short list syntax	✔	native	native	native	native	native	native	native	native
• Allow specifying keys in list()	✔	native	native	native	native	native	native	native	native
• Nullabe types	✔(1)	native	native	native	native	native	native	native	native
PHP 7.0
• Unicode escape sequences	native	native	native	native	native	native	native	native	native
• Grouped use	✔(2)	✔(2)	✔(2)	✔(2)	✔(2)	✔(2)	✔(2)	✔(2)	✔(2)
• Null coalesce (??)	native	native	native	native	native	native	native	native	native
• Comparison (<=>)	native	native	native	native	native	native	native	native	native
• Scalar types	native	native	native	native	native	native	native	native	native
• Return types	native	native	native	native	native	native	native	native	native
• Variable syntax	native	native	native	native	native	native	native	native	native
• Anonymous classes	native	native	native	native	native	native	native	native	native
• Keywords as methods	native	native	native	native	native	native	native	native	native
• Generator "yield from"	native	native	native	native	native	native	native	native	native
• Generator return	native	native	native	native	native	native	native	native	native

Notes:

1. Currently unchecked.
2. Namespaces are resolved by the compiler and emitted fully qualified.
3. Only in the correct order.
4. Except for class constants.
5. Emitted as void.
6. True and false types emitted as bool.