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Message-ID: <b48b84fe-c71f-b3e4-890c-8ccb26e6bdb0@asahilina.net>
Date:   Tue, 2 May 2023 22:59:24 +0900
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Subject: Re: [PATCH] rust: error: allow specifying error type on `Result`
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To:     Alice Ryhl <aliceryhl@google.com>, Miguel Ojeda <ojeda@kernel.org>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Alex Gaynor <alex.gaynor@gmail.com>
Cc:     Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?Q?Bj=c3=b6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        patches@lists.linux.dev
References: <20230502124015.356001-1-aliceryhl@google.com>
From:   Asahi Lina <lina@asahilina.net>
In-Reply-To: <20230502124015.356001-1-aliceryhl@google.com>
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On 02/05/2023 21.40, Alice Ryhl wrote:
> Currently, if the `kernel::error::Result` type is in scope (which is
> often is, since it's in the kernel's prelude), you cannot write
> `Result<T, SomeOtherErrorType>` when you want to use a different error
> type than `kernel::error::Error`.
> 
> To solve this we change the error type from being hard-coded to just
> being a default generic parameter. This still lets you write `Result<T>`
> when you just want to use the `Error` error type, but also lets you
> write `Result<T, SomeOtherErrorType>` when necessary.
> 
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> ---
>   rust/kernel/error.rs | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
> index 5f4114b30b94..01dd4d2f63d2 100644
> --- a/rust/kernel/error.rs
> +++ b/rust/kernel/error.rs
> @@ -177,7 +177,7 @@ impl From<core::convert::Infallible> for Error {
>   /// Note that even if a function does not return anything when it succeeds,
>   /// it should still be modeled as returning a `Result` rather than
>   /// just an [`Error`].
> -pub type Result<T = ()> = core::result::Result<T, Error>;
> +pub type Result<T = (), E = Error> = core::result::Result<T, E>;
>   
>   /// Converts an integer as returned by a C kernel function to an error if it's negative, and
>   /// `Ok(())` otherwise.
> 
> base-commit: ea76e08f4d901a450619831a255e9e0a4c0ed162

Reviewed-by: Asahi Lina <lina@asahilina.net>

~~ Lina