What is a best way to fork a substrate pallet?

Question

Context:

i'm building a "sub-treasury" pallet, and for it, i'd like to start from the existing substrate's pallet_treasury.

Problem:

In Cargo.toml, there is relative paths (like sp-io = {version=...... path="../../sp-io"} Obviously had to change it, but then in lib.rs, i had a loooooot of errors.

those errors are mainly "the trait frame_support::[something i can't use]::[the trait] is not implemented for [Proposal<...> or #[pallet::call]]

for example purpose, here is the first error given by cargo:

error[E0277]: the trait bound `pallet::Call<T, I>: frame_support::parity_scale_codec::WrapperTypeEncode` is not satisfied
   --> pallets/sub_treasury/src/lib.rs:296:12
    |
296 |     #[pallet::call]
    |               ^^^^ the trait `frame_support::parity_scale_codec::WrapperTypeEncode` is not implemented for `pallet::Call<T, I>`
    |
...
note: required by a bound in `frame_support::Callable::Call`
   --> /home/erudyx/.cargo/git/checkouts/substrate-7e08433d4c370a21/19162e4/frame/support/src/dispatch.rs:56:38
    |
56  |     type Call: UnfilteredDispatchable + Codec + Clone + PartialEq + Eq;
    |                                         ^^^^^ required by this bound in `frame_support::Callable::Call`

Question:

I'd like to know if there is a proper way to fork a pallet. Is there a specific branch to fork from ? A specific repo ? Is there a place where the procedure is documented ?

Answer 1

I tested these steps and they work just fine:

1. Copy the pallet folder you want to a new location. (I used my desktop)
2. Navigate to the copied pallet folder.
3. Modify Cargo.toml replacing path = "..." with git = "https://github.com/paritytech/substrate.git"
   • You can use the regular expression path = "[\S]+" to match on the path string.
4. Run cargo build in the folder.

If you run into any compiler issues, make sure to update your rust compiler:

• rustup update

EDIT:

As noted by the author, it is critical if you are building a forked crate in a larger Substrate project, that all versions / references to Substrate must be the same. You can quickly run into compiler errors if you have one crate which depends on one version of Substrate, and another crate depend on a different version.

Answer 2

Okey follow this steps

1. in the src/cargo.toml include the pallet ( its repo and which version you want to use)

2. Then include the pallet into workspace project/ cargo.toml -> There is workspace vector , include the path to your pallet

3. Then include it in the runtime/cargo.toml

4. Then import it in the runtime/src -> Then implement the neccessary trait require by the pallet. You can see example from balances pallet how its implemented in the runtime and Then Include it in the construct_runtime!