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From:   "Andreas Hindborg (Samsung)" <nmi@metaspace.dk>
To:     Qingsong Chen <changxian.cqs@antgroup.com>
Cc:     linux-kernel@vger.kernel.org,
        =?utf-8?B?55Sw5rSq5Lqu?= <tate.thl@antgroup.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        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>,
        Sergio =?utf-8?Q?Gonz=C3=A1lez?= Collado 
        <sergio.collado@gmail.com>, rust-for-linux@vger.kernel.org
Subject: Re: [PATCH v3] rust: macros: vtable: fix `HAS_*` redefinition
 (`gen_const_name`)
Date:   Wed, 09 Aug 2023 21:03:08 +0200
In-reply-to: <20230808025404.2053471-1-changxian.cqs@antgroup.com>
Message-ID: <87bkfgghqm.fsf@metaspace.dk>
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"Qingsong Chen" <changxian.cqs@antgroup.com> writes:

> If we define the same function name twice in a trait (using `#[cfg]`),
> the `vtable` macro will redefine its `gen_const_name`, e.g. this will
> define `HAS_BAR` twice:
>
>     #[vtable]
>     pub trait Foo {
>         #[cfg(CONFIG_X)]
>         fn bar();
>
>         #[cfg(not(CONFIG_X))]
>         fn bar(x: usize);
>     }
>
> Fixes: b44becc5ee80 ("rust: macros: add `#[vtable]` proc macro")
> Signed-off-by: Qingsong Chen <changxian.cqs@antgroup.com>

Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>

> ---
> v1 -> v2:
> - Use `BTreeSet` and existing `consts` as suggested by Alice and Gary.
> - Reword commit messages as suggested by Miguel.
> v2 -> v3:
> - No need to replace `HashSet` with `BTreeSet`, since `consts` is never
>   iterated on.
>
>  rust/macros/vtable.rs | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/rust/macros/vtable.rs b/rust/macros/vtable.rs
> index 34d5e7fb5768..ee06044fcd4f 100644
> --- a/rust/macros/vtable.rs
> +++ b/rust/macros/vtable.rs
> @@ -74,6 +74,7 @@ pub(crate) fn vtable(_attr: TokenStream, ts: TokenStream) -> TokenStream {
>                  const {gen_const_name}: bool = false;",
>              )
>              .unwrap();
> +            consts.insert(gen_const_name);
>          }
>      } else {
>          const_items = "const USE_VTABLE_ATTR: () = ();".to_owned();