The conflict between argh and anyhow

[twang2218]

To reproduce the issue, here is the code:

use anyhow::Ok;
use argh::FromArgs;

#[derive(FromArgs)]
/// A simple CLI tool
struct Args {
    /// the input file
    #[argh(option)]
    input: String,
}

fn main() -> anyhow::Result<()> {
    let args: Args = argh::from_env();
    println!("Hello, world!: input: {}", args.input);
    Ok(())
}

cargo build output:

cargo build
   Compiling argh_vs_anyhow v0.1.0 (/Users/tao/lab/rust/fortune/project/argh_vs_anyhow)
error[E0308]: mismatched types
 --> src/main.rs:4:10
  |
4 | #[derive(FromArgs)]
  |          ^^^^^^^^
  |          |
  |          expected `Result<Args, EarlyExit>`, found `Result<Args, Error>`
  |          expected `Result<Args, EarlyExit>` because of return type
  |
  = note: expected enum `Result<_, EarlyExit>`
             found enum `Result<_, anyhow::Error>`
  = note: this error originates in the derive macro `FromArgs` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0308]: mismatched types
 --> src/main.rs:4:10
  |
4 | #[derive(FromArgs)]
  |          ^^^^^^^^ expected `Result<String, String>`, found `Result<String, Error>`
  |
  = note: expected enum `Result<_, String>`
             found enum `Result<_, anyhow::Error>`
  = note: this error originates in the derive macro `FromArgs` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0308]: mismatched types
 --> src/main.rs:4:10
  |
4 | #[derive(FromArgs)]
  |          ^^^^^^^^
  |          |
  |          expected `Result<Vec<String>, EarlyExit>`, found `Result<Vec<String>, Error>`
  |          expected `Result<Vec<String>, EarlyExit>` because of return type
  |
  = note: expected enum `Result<_, EarlyExit>`
             found enum `Result<_, anyhow::Error>`
  = note: this error originates in the derive macro `FromArgs` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0308`.
error: could not compile `argh_vs_anyhow` (bin "argh_vs_anyhow") due to 3 previous errors

anyhow::Ok conflicted with core::result::Result Ok, so, I believe the fully qualified type path should be used in argh code to avoid the conflict.