HHVM 4.65 is released! This release marks the end of support for 4.58; HHVM 4.59–4.64 remain supported, as do the 4.32 and 4.56 LTS releases.

Highlights

is and as checks for reified enums now only check the underlying type, not the values; this makes them consistent with parameter and return type enforcement.
added _with_error() variants of preg functions, e.g. preg_grep_with_error(), preg_match_with_error(), preg_replace_with_error(), to avoid the need for preg_last_error() calls and the global state that entails.
added HH\is_vec_or_varray() and HH\is_dict_or_darray() functions.
clearer error messages when incompatible kinds extend each other - for example, a class can not extend an interface, but it can implement one.

Breaking Changes

array() literals are no longer supported by the parser; [] literals were already banned. Replace with darray[] or varray[]. On older versions of HHVM, hhast-migrate --php-arrays can be used to automate this.
the globals array has been removed - for example, HH\global_get('GLOBALS') now returns null. Fetch specific known keys instead.
- $GLOBALS['foo'] (i.e. with a key) is still supported, however migrating to HH\global_get('foo') is encouraged.
it is now a typechecker error to mark an abstract method as __Memoize; this was previously a runtime error.
yield from has been removed; the release notes for 4.64 contain suggestions for migrating.

(array) casts will be a parse error; they are currently a typechecker error. A runtime error can be enabled now with the new hhvm.hack.lang.disable_array_cast INI setting.