Fix build after SCALE v3.1 update

[HCastano]

Looks like parity-scale-codec-(derive) v3.1 introduced a breaking change with
paritytech/parity-scale-codec#325.

This PR specifies the path we use when pulling in the crate and fixes our failing
master build.

[paritytech-cicd-pr]

🦑 📈 ink! Example Contracts ‒ Changes Report 📉 🦑

These are the results when building the examples/* contracts from this branch with cargo-contract 0.17.0-2d43c18 and comparing them to ink! master:

	Δ Optimized Size	Δ Used Gas	Total Optimized Size	Total Used Gas
accumulator			1.03 K
adder			2.17 K
contract-introspection			2.37 K
contract-terminate			0.94 K	214_418
contract-transfer			8.15 K	14_418
delegator			6.37 K	46_295
dns			8.84 K	43_254
erc1155			17.23 K	86_508
erc20			8.49 K	43_254
erc721			11.81 K	115_344
flipper			1.31 K	14_418
incrementer			1.21 K	14_418
multisig			25.20 K	93_527
proxy			2.90 K	29_536
rand-extension			3.92 K	14_418
subber			2.19 K
trait-erc20			8.76 K	43_254
trait-flipper			1.00 K	14_418
trait-incrementer			1.19 K	28_836
upgradeable-contract			3.00 K

Link to the run | Last update: Tue Mar 15 02:16:16 CET 2022

[cmichi]

I wonder why we didn't get a dependabot PR. Maybe because we specify version = "3" ?

[bkchr]

How did that break your build? What was the error?

[HCastano]

@bkchr My bad, I should linked the failed run in the PR description. See it here.

Relevant error:

test tests/ui/contract/pass/no-implicit-prelude.rs [should pass] ... error
┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈
error[E0433]: failed to resolve: use of undeclared crate or module `scale`
 --> tests/ui/contract/pass/no-implicit-prelude.rs:6:5
  |
6 |     pub struct Contract {}
  |     ^^^^^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `scale`
  |
  = note: this error originates in the derive macro `::scale::Encode` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0433]: failed to resolve: use of undeclared crate or module `scale`
 --> tests/ui/contract/pass/no-implicit-prelude.rs:6:5
  |
6 |     pub struct Contract {}
  |     ^^^^^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `scale`
  |
  = note: this error originates in the derive macro `::scale::Decode` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0433]: failed to resolve: use of undeclared crate or module `scale`
 --> tests/ui/contract/pass/no-implicit-prelude.rs:6:5
  |
6 |     pub struct Contract {}
  |     ^^^^^^^^^^^^^^^^^^^^^^ not found in `scale`
  |
help: consider importing this trait
  |
6 |     use scale::Encode;
  |
┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈

The UI test in question:

#![no_implicit_prelude]

#[::ink_lang::contract]
mod contract {
    #[ink(storage)]
    pub struct Contract {}

    impl Contract {
        #[ink(constructor)]
        pub fn constructor() -> Self {
            Self {}
        }

        #[ink(message)]
        pub fn message(&self) {}
    }
}

fn main() {}

We import parity-scale-codec as follows:

scale = { package = "parity-scale-codec", version = "3", default-features = false, features = ["derive"] }

Let me know if you need/want more info

[bkchr]

Here is the "correct" fix: paritytech/parity-scale-codec#328

Sorry for the bug