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transitive_subtypes

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.

Return all types which transitively extend, implement, or use the given base type, as (name, path, kind, abstract) tuples

namespace HH\Facts;

function transitive_subtypes<T>(
  classname<T> $base_type,
  ?DeriveFilters<string, dynamic> $filters = NULL,
): vec<(string, TypeKind, classname<T>, bool)>;

The 'kind' and 'derive_kind' filters passed in determine which relationships and types we look at while traversing the inheritance graph. So if you filter traits out, we'll exclude classes which are only related because they use a trait which implements the interface you passed in.

The 'attributes' filters passed in will be applied to the final list of transitive subtypes. So if you look for types with the <<Oncalls('team')>> attribute, we'll only filter the final list of subtypes, instead of ignoring all types that don't have the given attribute.

Throws InvalidOperationException if Facts is not enabled.

Parameters​

  • classname<T> $base_type
  • ?DeriveFilters<string, dynamic> $filters = NULL

Returns​

  • vec<(string, TypeKind, classname<T>, bool)>