Incorrect compiler error message about a trait import

[Yung-Beef]

I'm trying to hash something with BlakeTwo256::hash_of(data).into(), it told me I needed to add use frame::primitives::BlakeTwo256; and then said hash_of wasn't in scope and I should add use polkadot_sdk_frame::traits::Hash.

However, that doesn't exist, and I need use frame::traits::Hash.

I believe this is related to issue 3813 and possibly concerns lines 53-64 here, but I could not find where the compiler error is being generated from.

[ggwpez]

Can you post the whole error message please? The error is possibly generated by the compiler.

[Yung-Beef]

error[E0599]: no function or associated item named `hash_of` found for struct `BlakeTwo256` in the current scope
   --> src/tests.rs:504:40
    |
504 |         let new_dna: [u8; 32] = BlakeTwo256::hash_of(&unique_payload).into();
    |                                              ^^^^^^^ function or associated item not found in `BlakeTwo256`
    |
    = help: items from traits can only be used if the trait is in scope
help: trait `Hash` which provides `hash_of` is implemented but not in scope; perhaps you want to import it
    |
14  + use polkadot_sdk_frame::traits::Hash;
    |

@ggwpez

[Yung-Beef]

I know the package is named polkadot_sdk_frame and it's renamed or something inside the crate, is the compiler not able to understand that? If I try use polkadot_sdk_frame::traits::Hash; I get

error[E0433]: failed to resolve: use of undeclared crate or module `polkadot_sdk_frame`
  --> src/tests.rs:21:5
   |
21 | use polkadot_sdk_frame::traits::Hash;
   |     ^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `polkadot_sdk_frame`

[gui1117]

Do you have a branch to look at to reproduce? also maybe rust version?

Nevermind I can reproduce:
Cargo.toml

[package]
name = "ressai"
version = "0.1.0"
edition = "2021"

[dependencies]
frame = { package = "polkadot-sdk-frame", git = "https://github.com/paritytech/polkadot-sdk.git", branch = "master", features = ["experimental", "runtime", "std"] }

main.rs

 use frame::traits::BlakeTwo256;

fn main() {
	let new_dna: [u8; 32] = BlakeTwo256::hash_of(&3u32).into();
}

[gui1117]

This is a rustc error.
I reproduce in this repo: https://github.com/gui1117/debug_rustc_suggestion
It seems related to this issue: rust-lang/rust#52485