typecheck

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Typecheck the currently running endpoint with a given hh_client

namespace HH\Client;

function typecheck(
  string $client_name = 'hh_client',
): TypecheckResult;

Does some caching to hopefully be pretty cheap to call, especially when there are no errors and the code isn't changing. Relies on hh_server to poke a stamp file to say "something has changed" to invalidate our cache.

TODO Areas for future improvement:

Key the cache by endpoint/hhconfig location, so that we correctly support more than one project per HHVM instance.
Populate the cache separately from this function, so that typecheck_and_error can have a hot path that just checks "is the world clean" without paying the apc_fetch deserialization cost (which is most of the cost of this function, if I'm benchmarking correctly).
Storing an array (instead of an object) in APC might be faster, due to the way I think HHVM can optimize COW arrays.

Parameters

string $client_name = 'hh_client'

Returns

TypecheckResult

Parameters​

Returns​

Parameters

Returns