Cmp

:::info[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. :::

Does the PHP style behaviour when doing <, <=, >, >=, <=>

namespace HH\Lib\Legacy_FIXME;

function cmp(
  mixed $l,
  mixed $r,
): int;

tl/dr this involves a lot of potential implicit coercions. see __cast_and_compare for the complete picture.

Parameters

• mixed $l
• mixed $r

Returns

• int