the way that options end up invalidating memoized runs of

@rules

in the engine is that currently: 1) the

OptionsBootstrapper

is a

Param

, 2) `Subsystem`s are the return values of rules and sometimes

Param

s as well

so, the entire content of the

Subsystem

(via

__eq__

and

__hash__

) defines whether something that depends on it is invalidated

but 1) is a larger factor currently… because the

OptionsBootstrapper

comes in from the outside as a

Param

, eq/hash changes to the OB change the identity of rules that depend on it, transitively

ie for two non-equal OBs, there are two subgraphs

that is a thing that i’d love to try and fix as part of https://github.com/pantsbuild/pants/issues/10360 , because the OB fingerprinting is at the same time i) very coarse grained, ii) missing things

@happy-kitchen-89482: but to answer your original question directly: marking

fingerprint=True

on a

Subsystem

option has no effect due to (2). everything is included.