HHVM 4.3 is released! This release will be supported for 6 weeks, and HHVM 4.1+ remain supported.

Improvements and New Features

Fixed some cases where typechecker errors would be missing position data
Fixed potential bugs when using __LateInit in repo-authoritative mode
Autocomplete for parent:: now includes instance methods, not just static methods
VSDebug no longer intercepts STDERR when attaching to HHVM in server mode
Improved typechecker error for isset() usage

Breaking Changes

Improved consistency of raising errors for traits or interfaces that define constructors with parameter promotion; this is not supported.
Errors are now raised if an XHP class contains multiple child or category declarations; the first declaration would always be used. Muiltiple children and categories are still supported, but they must be in a single declaration.
Builtin function parameters will no longer be coerced - instead, an exception is thrown. On prior versions, warnings can be enabled on coercion with the hhvm.warn_on_coerce_builtin_params INI setting
Removed the <> operator; this can be replaced with !=, and is supported by hhast-migrate --hhvm-4.2-to-4.3 or hhast-migrate --ltgt-to-ne
Type errors are now raised if parent::__construct() is called with parameters that violate where constraints
Division by zero now throws an exception; this can be controlled with the hhvm.forbid_division_by_zero ini setting.
The typechecker is no longer aware of ext_session

Removed the hhvm.jit_profile_interp_requests INI setting as other changes made it unused
Removed the disable_optional_and_unknown_shape_fields experimental hhconfig option from 3.23.