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From:   ojeda@kernel.org
To:     Miguel Ojeda <ojeda@kernel.org>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= <bjorn3_gh@protonmail.com>
Cc:     rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        patches@lists.linux.dev
Subject: [PATCH v2 15/28] rust: str: add `b_str!` macro
Date:   Fri,  2 Dec 2022 17:14:46 +0100
Message-Id: <20221202161502.385525-16-ojeda@kernel.org>
In-Reply-To: <20221202161502.385525-1-ojeda@kernel.org>
References: <20221202161502.385525-1-ojeda@kernel.org>
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From: Gary Guo <gary@garyguo.net>

Add the `b_str!` macro, which creates a new `BStr` from
a string literal.

It is usable in const contexts, for instance:

    const X: &BStr = b_str!("Example");

Signed-off-by: Gary Guo <gary@garyguo.net>
[Reworded, adapted for upstream and applied latest changes]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/str.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 3aa1a0cb9bf8..95eb757c619d 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -9,6 +9,27 @@ use core::fmt;
 /// `BStr` is simply an alias to `[u8]`, but has a more evident semantical meaning.
 pub type BStr = [u8];
 
+/// Creates a new [`BStr`] from a string literal.
+///
+/// `b_str!` converts the supplied string literal to byte string, so non-ASCII
+/// characters can be included.
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::b_str;
+/// # use kernel::str::BStr;
+/// const MY_BSTR: &BStr = b_str!("My awesome BStr!");
+/// ```
+#[macro_export]
+macro_rules! b_str {
+    ($str:literal) => {{
+        const S: &'static str = $str;
+        const C: &'static $crate::str::BStr = S.as_bytes();
+        C
+    }};
+}
+
 /// Allows formatting of [`fmt::Arguments`] into a raw buffer.
 ///
 /// It does not fail if callers write past the end of the buffer so that they can calculate the
-- 
2.38.1