HHVM 4.13 is released! This release marks the end of support for the 4.7.x series.

Highlights

Fixed positions (incorrect ‘PRIMARY ERROR POSITION IS NOT IN CURRENT FILE’) for certain await expression that were implicitly rewritten as concurrent statements.
improved performance for is and as expressions with wildcard generics when not using repo-authoritative mode (~ 5x in some tests).
added hhvm.trust_autoloader_path option (defaults to false); if true, the autoloader will not invoke realpath.
improved subtyping of shapes.
calling undefined functions now only raises an unbound function typechecker error, instead of both an unbound function and unbound global constant error.
null checks in if statements now refine the type in both the if block and else block.
when Xenon is enabled, fix race condition that can lead to the HHVM process being terminated during startup.

Breaking Changes

zend_logo_guid(), zend_thread_id(), and zend_version() have been removed.
it is now a parse error to declare or invoke constructors with by-reference parameters.
removed HH\global_get_safe() as it functioned identically to HH\global_get().
improved shape subtyping can lead to needing to suppress error 4110 (type error) where error 4166 (unknown field) is currently suppressed.
assignments in ternary expressions can now assign type information - for example, after ($foo ? $x = 1 : $x = 2), $x is an int. This is expected to reduce the number of errors for safe code, but may raise new errors in some situations.
Shapes::keyExists($shape, 'field') now refines the type in the same way as $shape is shape('field' => mixed, ...). This is expected to reduce the number of errors for safe code, but may raise new errors in some situations.

To remove conflicts with other planned syntax changes, the syntax for soft type hints will be changing from @sometype $foo to <<__Soft>> sometype $foo; this new syntax is supported for experimental use.