HHVM 4.75 is released! This release marks the end of support for 4.68; HHVM 4.69–4.74 remain supported, as do the 4.32 and 4.56 LTS releases.


  • Continued improvements to the recently added highlighted error formatter.
  • The environment variable FORCE_ERROR_COLOR can be used to force hh_client to output color escape sequences even if the output is not a terminal, e.g. to save the output into a file that can be printed to a compatible terminal later.

Breaking Changes

  • is_array() is now equivalent to HH\is_any_array() (previously equivalent to HH\is_php_array()). We expect this to be the last step before is_array() is removed completely (it had already been removed from the typechecker since HHVM 4.71, but for now is still available at runtime), so please migrate to HH\is_any_array() (preserving the new behavior), HH\is_php_array() (preserving the old behavior), or another of the alternatives listed in HHVM 4.71 release notes.
  • The built-in functions call_user_func() and call_user_func_array() were deprecated. Using them raises a typechecker error, but for now still works at runtime (we expect runtime support to also be removed soon).
    • Use $callable() instead, where $callable is an anonymous function, or the return value from fun(), class_meth(), inst_meth() or meth_caller(). All of these are understood by the typechecker, so the change may reveal previously hidden errors.
    • Using a string as $callable raises a typechecker error, but for now still works at runtime. However, we expect it to stop working soon, as the native “function pointer” types returned by the functions above will become the only valid representations of functions and methods.
  • The INI option hhvm.emit_func_pointers has been removed, fun() now always returns a native “function pointer” type instead of a string.
    • hhvm.emit_cls_meth_pointers and other related flags are also expected to be removed soon.
  • The type of exception thrown when using a string key (instead of int) to index into a varray changed from OutOfBoundsException to InvalidArgumentException.
    • In previous HHVM versions, the hhvm.hack_arr_compat_notices INI option can be used to raise a notice (in addition to the OutOfBoundsException) in these cases.
  • Changed behavior of the > and >= operators on varrays to be consistent with vecs. This only affects rare cases such as comparing arrays of objects or NAN values.
    • Both before and after this change, comparing any array types using these operators raises a typechecker error and often has surprising and inconsistent results at runtime, so it should be avoided.

Future Changes

  • is_array() will be removed completely.
  • Support for using strings or tuples to represent functions and methods will be removed in a future release. They are being replaced by a native “function pointer” type.
    • Using fun() or another option listed above guarantees that the return value will be compatible with the specific HHVM version being used, no matter which type it uses to represent functions.