HHVM 4.36 is released! This release marks the end of support for 4.30; 4.31–4.35 remain supported, as does the 4.8 LTS release.


  • Statically links jemalloc 5 if the system version is older. HHVM requires 2MB-aligned 2MB allocations; older versions of jemalloc will give a 4MB allocation, leading to request OOMs. Some old versions of HHVM detected the 4MB allocation and attempted to use it, but did not do so correctly.
  • Symbol search in IDEs now finds namespaced symbols again.
  • Fixed the “Unbound name” typechecker error (2049) to correctly report the type of the missing entity (“an object type”, “a global function”, etc.). Previously it would incorrectly say “an object type” in most cases.

Breaking Changes

  • It is now a runtime error to declare multiple constants with the same name. It had already been a typechecker error, but only a notice at runtime.
  • It is now a typechecker error for a static method to use a reified generic type parameter from the encompassing class. The generic type parameter must instead be reified at the static method itself.
  • Fixed a bug causing the typechecker to not report missing generic type parameters for class constants.
  • Fixed incorrect typehints for some built-in sorting functions (asort, arsort, krsort, uasort, uksort). These functions may change the type of the passed-in container (e.g. vec to dict), which the original typehints didn’t account for. This change may reveal new type errors in code that uses these functions.