Display real extrinsic costs when interacting with contracts

[athei]

With an upcoming PR (paritytech/substrate#5712) the weight and therefore the fees of any contract related extrinsic will reflect the real costs of that extrinsic. Previously the gas costs where on top as a completely separate matter. This distinction is gone.

That means the TransactionPaymentApi::query_info will take into account the gas_limit of an extrinsic (or the code length for put_code) and returns the complete costs for the sender as for any other extrinsic.

However, during my tests with the linked PR I noticed that for the contracts module the costs that the UI displayed when sending an extrinsic stays fixed no matter what gas limit I supply:

This is different from other modules where this fee seems to change when the weight of an extrinsic changes given another input. I guess that this behavior is somehow disabled in the contracts UI.

I suppose to display the fees as calculated by TransactionPaymentApi::query_info when submitting a contract extrinsic as for any other extrinsic. However, we should change the wording slightly as those costs are a maximum and the rest is refunded. This is true for all extrinsics lately but contracts might be an extreme case. I propose something like this:

According to (your entered gas limit | the length of the supplied wasm blob) fees of at most $UNIT Unit will be applied to the submission

[jacogr]

Please move this to substrate - the UI calls query_paymentInfowhich has the estimation. If incorrect, it is not returning the correct results.

[athei]

I cannot find a function with this name. Is this distinct from the TransactionPaymentApi::query_info I mentioned?

[jacogr]

https://polkadot.js.org/api/substrate/rpc.html#queryinfo-extrinsic-bytes-at-blockhash-runtimedispatchinfo

https://github.com/paritytech/substrate/blob/master/frame/transaction-payment/rpc/src/lib.rs#L33

[athei]

I did a little investigation. Everything is working as intended. I mistakenly thought that the weight contribution was not accounted for. In reality the numbers were just too small to notice it in the UI because of #2604. So nothing is to be done here.

[polkadot-js-bot]

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