unresolved import sc_rpc::Metadata

Question

i try to import fc-rpc on fronter. but got some error message

Compiling fc-rpc v2.0.0-dev (https://github.com/paritytech/frontier.git#9d4ccba8)
error[E0432]: unresolved import `sc_rpc::Metadata`
  --> /home/kula/.cargo/git/checkouts/frontier-b4643f17507d3282/9d4ccba/client/rpc/src/eth_pubsub.rs:38:5
   |
38 | use sc_rpc::Metadata;
   |     ^^^^^^^^^^^^^^^^ no `Metadata` in the root

For more information about this error, try `rustc --explain E0432`.
error: could not compile `fc-rpc` due to previous error
warning: build failed, waiting for other jobs to finish...

what's wrong with this?

my rust toolcain

[toolchain]
channel = "nightly"
components = [ "rustfmt", "clippy" ]
targets = [ "wasm32-unknown-unknown" ]
profile = "minimal"

Answer 1

In a newer release of the sc-rpc, the Metadata struct was removed. Unfortunately, fc-rpc (Frontier's rpc pallet) is not yet compatible with this change.

The simplest fix right now is to run cargo update -p <the-imported-pallet> --precise 1e0807fb477b21edd373eb88778336d5ff23d3a7

This will set the pallet you are importing to use the commit 1e0807fb477b21edd373eb88778336d5ff23d3a7. This commit uses a compatible version of sc-rpc.

Unfortunately, adding rev = 1e0807fb477b21edd373eb88778336d5ff23d3a7 into your Cargo.toml will not work. Cargo has a bug right now that duplicates dependencies (with the exact same code, Cargo just does not recognize it).