How to enable `std` features in pallets?

Question

I'm trying to implement simple PoW for my node. After debugging all other stuff I've encountered the problem where finality-grandpa and storage do not get compiled because standard library macros are (for some reason) out of scope.

I've checked that std features and enabled for all dependencies where they need to be enabled. Also I found this information about one of the dependencies. But as it's a non-local (pulled from github) I can't change that functionality.

Please note that I did not modify any of these two pallets (just imported my own, implementing PoW). Before that (on clear substrate-node-template which I use as a base for my project) those built without any problem.

The question is: How do I fix this? Should I enable std for these crates somehow? As far as I know, the node is built into native Rust and WASM, and for WASM it's built in no-std. By why did it build before in this case?

Here is a part of the error message I get:

cargo build --release 
    Updating crates.io index
    Updating git repository `https://github.com/paritytech/substrate.git`
    Updating git repository `https://github.com/paritytech/substrate`
   Compiling node-template-runtime v4.0.0-dev (/home/creestl/programming/blockchain/crain/runtime)
error: failed to run custom build command for `node-template-runtime v4.0.0-dev (/home/creestl/programming/blockchain/crain/runtime)`
 
Caused by:
  process didn't exit successfully: `/home/creestl/programming/blockchain/crain/target/release/build/node-template-runtime-d1d0301f1ce42478/build-script-build` (exit status: 1)
  --- stdout
  Information that should be included in a bug report.
  Executing build command: "rustup" "run" "nightly" "cargo" "rustc" "--target=wasm32-unknown-unknown" "--manifest-path=/home/creestl/programming/blockchain/crain/target/release/wbuild/node-template-runtime/Cargo.toml" "--color=always" "--profile" "release"
  Using rustc version: rustc 1.62.0-nightly (de1bc0008 2022-04-21)
 
 
  --- stderr
     Compiling frame-support v4.0.0-dev (https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.18#fc3fd073)
     Compiling sp-finality-grandpa v4.0.0-dev (https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.18#fc3fd073)
  error: cannot find macro `format` in this scope
    --> /home/creestl/.cargo/git/checkouts/substrate-7e08433d4c370a21/fc3fd07/primitives/finality-grandpa/src/lib.rs:43:2
     |
  43 |     app_crypto!(ed25519, GRANDPA);
     |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = note: consider importing one of these items:
             alloc::format
             scale_info::prelude::format
     = note: this error originates in the macro `$crate::app_crypto_public_common_if_std` (in Nightly builds, run with -Z macro-backtrace for more info)
 
  error[E0433]: failed to resolve: use of undeclared crate or module `std`
    --> /home/creestl/.cargo/git/checkouts/substrate-7e08433d4c370a21/fc3fd07/primitives/finality-grandpa/src/lib.rs:43:2
     |
  43 |     app_crypto!(ed25519, GRANDPA);
     |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `std`
     |
     = note: this error originates in the macro `$crate::app_crypto_public_common_if_std` (in Nightly builds, run with -Z macro-backtrace for more info)
 
  error[E0433]: failed to resolve: use of undeclared type `String`
    --> /home/creestl/.cargo/git/checkouts/substrate-7e08433d4c370a21/fc3fd07/primitives/finality-grandpa/src/lib.rs:43:2
     |
  43 |     app_crypto!(ed25519, GRANDPA);
     |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
     |
     = note: this error originates in the macro `$crate::app_crypto_public_common_if_std` (in Nightly builds, run with -Z macro-backtrace for more info)
  help: consider importing one of these items
     |
  42 |     use alloc::string::String;
     |
  42 |     use codec::alloc::string::String;
     |
  42 |     use scale_info::prelude::string::String;
     |

And here is a link to the repo with my last changes

Answer 1

standard library macros are (for some reason) out of scope.

TL;DR: you cannont use std in runtime development

As you see on the node template all runtime files must not use std because they target Wasm, and thus cannot generally use the full std, and include:

#![cfg_attr(not(feature = "std"), no_std)]

Instead of the full library, the general subset of std types and traits you likely need are in sp_std. This includes primitives like str and vec modules. Of note, it's likely for runtime development frame_support::storage::BoundedVec should be used though, as boundedness is typically critical in runtimes).

Answer 2

I've fixed it. The reason for the bug was that I've included

getrandom = {version = "0.2", features= ["js"] }  

in Cargo.toml of one of my crates. And that caused some inner conflicts. After I removed that dependency - everything was OK