Serialize/Deserialize WeightedIndex<T> is not enabled with feature "serde1"

[CGMossa]

Common issues

Problem: WeightedIndex<T> is not serializeable.

Quick solution: Skipping it, but even using rand = {version = "0.7.3", features = ["serde1"]}
didn't amend the issue.

Details: I am curious as to whether it is possible to make this a Serialize/Deserialize pairing.
If so, would be happy to provide a PR.

[dhardy]

Yes, I believe that's just an oversight.

A PR would be welcome. Note that master now has breaking changes since 0.7.

[CGMossa]

I tried a little bit, and faced an issue already. I need to add Serialize and Deserialize to the impl-block of WeightedIndex, but then this is not possible unless I include serde as a dependency.

Do you know how I can make a gated (with maybe cfg?) that enables me to add constraints if a feature is selected?

[dhardy]

Ah, this is beacuse:

Cargo.toml
27:serde1 = [] # does nothing, deprecated

this used to be a dependency of Rand but is no longer. In contrast:

rand_core/Cargo.toml
24:serde1 = ["serde"] # enables serde for BlockRng wrapper
27:serde = { version = "1", features = ["derive"], optional = true }

@newpavlov @vks I think we can make serde a dependency again?

[vks]

Fixed with #974.