unknown tool name \redpen\ in scoped lint when invoking redpen

[jrvanwhy]

I'm unable to successfully run Redpen 0.3.0. I think there's a bug in either redpen or redpen_wrapper, but it's also possible that this is user error.

Reproduction steps: Install Redpen using cargo +nightly-2023-11-01 install redpen-linter, and create a project with the following sources:

Cargo.toml:

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

rust-toolchain.toml:

[toolchain]
channel = "nightly-2023-11-01"

src/lib.rs:

//#![feature(register_tool)]
//#![register_tool(redpen)]
#[deny(redpen::panics)]
pub fn redpen_test() {
    panic!("Explicit panic that should make redpen error.");
}

When I invoke redpen, I get:

jrvanwhy@jrvanwhy:~/playground$ redpen
[... Cargo compiling dependency crates snipped ...]
   Compiling redpen_test v0.1.0 (/home/jrvanwhy/playground)
error[E0710]: unknown tool name `redpen` found in scoped lint: `redpen::panics`
 --> src/lib.rs:3:8
  |
3 | #[deny(redpen::panics)]
  |        ^^^^^^
  |
  = help: add `#![register_tool(redpen)]` to the crate root

For more information about this error, try `rustc --explain E0710`.
    Finished dev [unoptimized + debuginfo] target(s) in 26.11s

If I uncomment the #![feature(register_tool)] and #![register_tool(redpen)] lines, I get:

jrvanwhy@jrvanwhy:~/playground$ redpen
   Compiling redpen_test v0.1.0 (/home/jrvanwhy/playground)
error: tool `redpen` was already registered
 --> <crate attribute>:1:15
  |
1 | register_tool(redpen)
  |               ^^^^^^
  |
 ::: src/lib.rs:2:18
  |
2 | #![register_tool(redpen)]
  |                  ------ already registered here

error[E0636]: the feature `register_tool` has already been declared
 --> <crate attribute>:1:9
  |
1 | feature(register_tool)
  |         ^^^^^^^^^^^^^

For more information about this error, try `rustc --explain E0636`.
    Finished dev [unoptimized + debuginfo] target(s) in 0.09s