Re-implement concat_idents! in libmacros

drivers/android/defs.rs

@@ -9,7 +9,7 @@ use kernel::{
 
 macro_rules! pub_no_prefix {
     ($prefix:ident, $($newname:ident),+) => {
-        $(pub(crate) const $newname: u32 = concat_idents!($prefix, $newname);)+
+        $(pub(crate) const $newname: u32 = kernel::macros::concat_idents!($prefix, $newname);)+
     };
 }
 

rust/kernel/lib.rs

@@ -14,7 +14,6 @@
 #![no_std]
 #![feature(allocator_api)]
 #![feature(associated_type_defaults)]
-#![feature(concat_idents)]
 #![feature(const_mut_refs)]
 #![feature(const_ptr_offset_from)]
 #![feature(const_refs_to_cell)]
@@ -41,6 +40,8 @@ mod allocator;
 #[doc(hidden)]
 pub use bindings;
 
+pub use macros;
+
 #[cfg(CONFIG_ARM_AMBA)]
 pub mod amba;
 pub mod chrdev;

rust/macros/concat_idents.rs

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use proc_macro::{token_stream, Ident, TokenStream, TokenTree};
+
+use crate::helpers::expect_punct;
+
+fn expect_ident(it: &mut token_stream::IntoIter) -> Ident {
+    if let Some(TokenTree::Ident(ident)) = it.next() {
+        ident
+    } else {
+        panic!("Expected Ident")
+    }
+}
+
+pub(crate) fn concat_idents(ts: TokenStream) -> TokenStream {
+    let mut it = ts.into_iter();
+    let a = expect_ident(&mut it);
+    assert_eq!(expect_punct(&mut it), ',');
+    let b = expect_ident(&mut it);
+    assert!(it.next().is_none(), "only two idents can be concatenated");
+    let res = Ident::new(&(a.to_string() + &b.to_string()), b.span());
+    TokenStream::from_iter([TokenTree::Ident(res)])
+}

rust/macros/lib.rs

@@ -2,6 +2,7 @@
 
 //! Crate for all kernel procedural macros.
 
+mod concat_idents;
 mod helpers;
 mod module;
 mod vtable;
@@ -144,3 +145,46 @@ pub fn module(ts: TokenStream) -> TokenStream {
 pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
     vtable::vtable(attr, 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)
+}

scripts/Makefile.build

@@ -275,7 +275,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
 # Compile Rust sources (.rs)
 # ---------------------------------------------------------------------------
 
-rust_allowed_features := allocator_api,bench_black_box,concat_idents,core_ffi_c,generic_associated_types,const_ptr_offset_from,const_refs_to_cell
+rust_allowed_features := allocator_api,bench_black_box,core_ffi_c,generic_associated_types,const_ptr_offset_from,const_refs_to_cell
 
 rust_common_cmd = \
 	RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \