remove the random builtin function

[xermicus]

It is unsafe for most use-cases and will be deprecated in ink!. Contract authors should rather use VRF from chain extensions or oracles.

The seal_random API is still used to calculate the salt on instantiation (if it is missing). There will be a new API seal_nonce which can be used to replace this. I'll do this in another PR once the new nonce API is available in pallets contract.

Side note: In my opinion it is completely safe to remove this built in. It was completely broken for IDK exactly how long but no one complained.

[athei]

Thanks. Looks good to me. I don't see seal_random being removed from the backend, though.

[seanyoung]

Thanks. Looks good to me. I don't see seal_random being removed from the backend, though.

Would it make sense to keep this function in solang until VRF is usable from solang?

Also out of curiosity, what was broken with the implementation of seal_random()? I thought it was very nice.

[xermicus]

Would it make sense to keep this function in solang until VRF is usable from solang?

We still need it during contract instantiation, if the salt is missing. I'll remove it completely as soon as the nonce API is available. As for now I don't think we should be too concerned about providing VRF to the users directly via solang... I think it is 1. too specific depending on the target runtime env and 2. it can be done in user space / via oracles or chain extensions.

Also out of curiosity, what was broken with the implementation of seal_random()? I thought it was very nice.

It is potentially predictable.

[LucasSte]

remove random builtin

This title seems like you have randomly chosen a builtin in Solang and removed it.

[LucasSte]

Please change your PR's title to something less ambiguous.
A suggestion would be Remove Substrate 'random' builtin.