diff options
author | Björn Roy Baron <bjorn3_gh@protonmail.com> | 2022-11-10 19:41:17 +0300 |
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committer | Miguel Ojeda <ojeda@kernel.org> | 2022-12-04 03:59:04 +0300 |
commit | 60f18c225f5f6939e348c4b067711d10afd33151 (patch) | |
tree | 7f60e3ef1510b5f5645a19f6197655921d8b4127 /rust/macros/lib.rs | |
parent | c3630df66f95e6c18987734b39f0239303dd72d8 (diff) | |
download | linux-60f18c225f5f6939e348c4b067711d10afd33151.tar.xz |
rust: macros: add `concat_idents!` proc macro
This macro provides similar functionality to the unstable feature
`concat_idents` without having to rely on it.
For instance:
let x_1 = 42;
let x_2 = concat_idents!(x, _1);
assert!(x_1 == x_2);
It has different behavior with respect to macro hygiene. Unlike
the unstable `concat_idents!` macro, it allows, for example,
referring to local variables by taking the span of the second
macro as span for the output identifier.
Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Reviewed-by: Finn Behrens <me@kloenk.dev>
Reviewed-by: Gary Guo <gary@garyguo.net>
[Reworded, adapted for upstream and applied latest changes]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust/macros/lib.rs')
-rw-r--r-- | rust/macros/lib.rs | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 91764bfb1f89..15555e7ff487 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -2,6 +2,7 @@ //! Crate for all kernel procedural macros. +mod concat_idents; mod helpers; mod module; @@ -70,3 +71,46 @@ use proc_macro::TokenStream; pub fn module(ts: TokenStream) -> TokenStream { module::module(ts) } + +/// Concatenate two identifiers. +/// +/// This is useful in macros that need to declare or reference items with names +/// starting with a fixed prefix and ending in a user specified name. The resulting +/// identifier has the span of the second argument. +/// +/// # Examples +/// +/// ```ignore +/// use kernel::macro::concat_idents; +/// +/// macro_rules! pub_no_prefix { +/// ($prefix:ident, $($newname:ident),+) => { +/// $(pub(crate) const $newname: u32 = kernel::macros::concat_idents!($prefix, $newname);)+ +/// }; +/// } +/// +/// pub_no_prefix!( +/// binder_driver_return_protocol_, +/// BR_OK, +/// BR_ERROR, +/// BR_TRANSACTION, +/// BR_REPLY, +/// BR_DEAD_REPLY, +/// BR_TRANSACTION_COMPLETE, +/// BR_INCREFS, +/// BR_ACQUIRE, +/// BR_RELEASE, +/// BR_DECREFS, +/// BR_NOOP, +/// BR_SPAWN_LOOPER, +/// BR_DEAD_BINDER, +/// BR_CLEAR_DEATH_NOTIFICATION_DONE, +/// BR_FAILED_REPLY +/// ); +/// +/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK); +/// ``` +#[proc_macro] +pub fn concat_idents(ts: TokenStream) -> TokenStream { + concat_idents::concat_idents(ts) +} |