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From: Alice Ryhl <aliceryhl@google.com>
Date: Thu, 25 Jan 2024 10:08:35 +0100
Message-ID: <CAH5fLgiwRDcyaxbcUNY8M1c_w11vkCWyRfqVVrN9Sgc7XYT0xw@mail.gmail.com>
Subject: Re: [PATCH] rust: str: add to_ascii_{upper,lower}case() to CString
To: Danilo Krummrich <dakr@redhat.com>
Cc: ojeda@kernel.org, alex.gaynor@gmail.com, wedsonaf@gmail.com, 
	boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, 
	benno.lossin@proton.me, a.hindborg@samsung.com, 
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org
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On Mon, Jan 22, 2024 at 7:46=E2=80=AFPM Danilo Krummrich <dakr@redhat.com> =
wrote:
> +    /// Converts the whole CString to lowercase.
> +    pub fn to_ascii_lowercase(&mut self) {
> +        self.buf.make_ascii_lowercase();
> +    }
> +
> +    /// Converts the whole CString to uppercase.
> +    pub fn to_ascii_uppercase(&mut self) {
> +        self.buf.make_ascii_uppercase();
> +    }
>  }

It looks like these methods are defined on `CString`. However, there's
no requirement that you need *ownership* of the c string to change its
contents - you just need mutable access.

I think it would make more sense to introduce an `impl DerefMut for
CString` that returns a `&mut CStr`, and then define these methods on
`CStr` as `&mut self`. That way, you can still call them on `CString`,
but you can also call it on other mutable c strings.

Alice