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From: Alice Ryhl <aliceryhl@google.com>
Date: Tue, 2 Apr 2024 11:46:11 +0200
Message-ID: <CAH5fLggN2PQeZs2pwR1EEeA6_O=xUo3=UvUgcuo=9YNtaBNrJw@mail.gmail.com>
Subject: Re: [PATCH] rust: types: Make Opaque::get const
To: Boqun Feng <boqun.feng@gmail.com>
Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, 
	Miguel Ojeda <ojeda@kernel.org>, Alex Gaynor <alex.gaynor@gmail.com>, 
	Wedson Almeida Filho <wedsonaf@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>, Andreas Hindborg <a.hindborg@samsung.com>, 
	Martin Rodriguez Reboredo <yakoyoku@gmail.com>, Obei Sideg <linux@obei.io>
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On Mon, Apr 1, 2024 at 11:46=E2=80=AFPM Boqun Feng <boqun.feng@gmail.com> w=
rote:
>
> To support a potential usage:
>
>     static foo: Opaque<Foo> =3D ..; // Or defined in an extern block.
>
>     ...
>
>     fn bar() {
>         let ptr =3D foo.get();
>     }
>
> `Opaque::get` need to be `const`, otherwise compiler will complain
> because calls on statics are limited to const functions.
>
> Also `Opaque::get` should be naturally `const` since it's a composition
> of two `const` functions: `UnsafeCell::get` and `ptr::cast`.
>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>