Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:8 as permitted sender) client-ip=2620:137:e000::3:8;
Date:   Sat, 25 Nov 2023 15:02:00 +0000
To:     Greg KH <gregkh@linuxfoundation.org>
From:   Benno Lossin <benno.lossin@proton.me>
Cc:     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>,
        Andreas Hindborg <a.hindborg@samsung.com>,
        Alice Ryhl <aliceryhl@google.com>,
        Martin Rodriguez Reboredo <yakoyoku@gmail.com>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] rust: macros: allow generic parameter default values in `#[pin_data]`
Message-ID: <t4HJjY0Oft2K2H1ssXTxZchdPTx25J6WqSJqAx75NiRUYg40BBLt1AHxm9ZF0UA70FkqIXb6Pp2sz3BErD-AyXmQCkU4xDvqyXHSinaWGb4=@proton.me>
In-Reply-To: <2023112525-impatient-untwist-ee3d@gregkh>
References: <20231125125024.1235933-1-benno.lossin@proton.me> <20231125125024.1235933-2-benno.lossin@proton.me> <2023112525-impatient-untwist-ee3d@gregkh>
Feedback-ID: 71780778:user:proton
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On 25.11.23 15:26, Greg KH wrote:
> On Sat, Nov 25, 2023 at 12:51:09PM +0000, Benno Lossin wrote:
>> This patch adds compatibilty for generic parameters defaults by using
>> the newly introduced `decl_generics` instead of the `impl_generics`.
>=20
> This says _what_ is happening here, but not _why_ this is needed at all.
>=20
> Try taking a look a the kernel documentation for how to write a good
> changelog text to make this much better.  It's often times the most
> difficult portion of making a kernel patch, the code is easy, writing a
> summary of why everyone else should agree that this code is acceptable
> is hard.

The reason is hidden in the third patch. Without this, the `#[pin_data]
macro would not allow specifying const generic parameter default values
and instead emit a compile error. I will add this to v2.

--=20
Cheers,
Benno