HHVM 4.10 is released! This release marks the end of support for the 4.4.x series.


  • Callable properties can now be invoked by parenthesizing, e.g. ($foo->bar)().
  • await expressions are now supported in XHP contexts, e.g. <foo bar={await baz()}>{await foo()}</foo>.

Breaking Changes

  • runtime support for alternate control-flow syntax (if: else: endif;) has been removed; this was previously banned by the typechecker in hack files, but supported at runtime.
  • warnings are now raised when arguments to builtin Hack functions are coerced to match the type.
  • by-ref assignemnts ($x = &$y) are no longer supported by the parser.