Support new `ink!` contract events

[ascjones]

Support new `ink!` contract events

[cmichi]

@jacogr We would be very grateful if you could tackle this soonish. The context is that we're about to release ink! 5.0 and just now realized that polkadot-js/api needs to be updated.

[cmichi]

I'm uploading a zip with two contracts here: erc20-4.0-vs-5.0.zip. It contains:

• ERC-20 with ink! 4.0
• ERC-20 with ink! 5.0

The diff comes down to

    "events": [
      {
        "args": [ ... ],
        "docs": [ ... ],
        "label": "...",
+       "module_path": "erc20::erc20",
+       "signature_topic": "0xb5b61a3e6a21a16be4f044b517c28ac692492f73c5bfd3f60178ad98c767f4cb"
      },
      ...
  ]

[peetzweg]

@ascjones Is this actually ink! specific? Would ask! and solang compiled contract emit events in the same way?

[ascjones]

@ascjones Is this actually ink! specific? Would ask! and solang compiled contract emit events in the same way?

I'm not sure what the current state is, but we would expect them to emit events in this way in the future i.e. have the first topic be the signature topic and include that in the metadata. /cc @xermicus

[peetzweg]

Would be a bit of a hassle to not only treat contract compiled with different ink version differently but also languages. Is there something like an language overarching specification how pallet-contracts wasm contracts should behave?

[cmichi]

That's basically the ink! metadata. Solang & co just implement the same metadata format as ink!, Solang also uses the ink! crates for parts of that. I think Solang is still on the Metadata v4.

When interpreting the metadata there should be no language-specific logic needed.

[xermicus]

Yes as soon as ink! 5.0 is released I'll keep Solang up and make a new release. As for the events, this shouldn't be any issue to adapt.

In general the metadata is mostly compatible. The only compromise so far is about how Solang Solidity contracts make use of lang_error, because the concepts of errors and error handling is fundamentally different between Solidity and ink!. We might be able to solve this by changing ink! metadata. Maybe it's also just way more pragramatic to just have some "special cases" instead of trying to make the ink! metadata format too generic (I don't have a hard opinion). But this is the status quo already and not related to events, which I should be able to adapt in solang without problems.