Hi,
when defining features for a Cargo package I questioned how I can define valid feature combinations.

For example lets imagine you have one or more supportive (backend) features, which can be used/consumed within other features. They could provide a service.

Then it's relatively simple to declare a dependency like this:

[features]
service_feature_c = []
consuming_feature_a = ["service_feature_c"]
consuming_feature_b = ["service_feature_c"]

i.e. you can express that
(a OR b) => c (in the case of an optional feature, you probably do not declare it as a dependency)

but you can't declare additional conditions about the inverse direction. i.e. it should not be allowed to enable c without a or b (i.e. c alone does not provide any value without a or b).
c => (a OR b)

Is there a common approach to handle this by somehow disallowing invalid or unsupported feature combinations?

BR

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