mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-18 00:24:58 +08:00
071cedc84e
Add a derive proc-macro for the `Zeroable` trait. The macro supports structs where every field implements the `Zeroable` trait. This way `unsafe` implementations can be avoided. The macro is split into two parts: - a proc-macro to parse generics into impl and ty generics, - a declarative macro that expands to the impl block. Suggested-by: Asahi Lina <lina@asahilina.net> Signed-off-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230814084602.25699-4-benno.lossin@proton.me [ Added `ignore` to the `lib.rs` example and cleaned trivial nit. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
73 lines
2.6 KiB
Rust
73 lines
2.6 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
|
|
|
|
use crate::helpers::{parse_generics, Generics};
|
|
use proc_macro::{TokenStream, TokenTree};
|
|
|
|
pub(crate) fn derive(input: TokenStream) -> TokenStream {
|
|
let (
|
|
Generics {
|
|
impl_generics,
|
|
ty_generics,
|
|
},
|
|
mut rest,
|
|
) = parse_generics(input);
|
|
// This should be the body of the struct `{...}`.
|
|
let last = rest.pop();
|
|
// Now we insert `Zeroable` as a bound for every generic parameter in `impl_generics`.
|
|
let mut new_impl_generics = Vec::with_capacity(impl_generics.len());
|
|
// Are we inside of a generic where we want to add `Zeroable`?
|
|
let mut in_generic = !impl_generics.is_empty();
|
|
// Have we already inserted `Zeroable`?
|
|
let mut inserted = false;
|
|
// Level of `<>` nestings.
|
|
let mut nested = 0;
|
|
for tt in impl_generics {
|
|
match &tt {
|
|
// If we find a `,`, then we have finished a generic/constant/lifetime parameter.
|
|
TokenTree::Punct(p) if nested == 0 && p.as_char() == ',' => {
|
|
if in_generic && !inserted {
|
|
new_impl_generics.extend(quote! { : ::kernel::init::Zeroable });
|
|
}
|
|
in_generic = true;
|
|
inserted = false;
|
|
new_impl_generics.push(tt);
|
|
}
|
|
// If we find `'`, then we are entering a lifetime.
|
|
TokenTree::Punct(p) if nested == 0 && p.as_char() == '\'' => {
|
|
in_generic = false;
|
|
new_impl_generics.push(tt);
|
|
}
|
|
TokenTree::Punct(p) if nested == 0 && p.as_char() == ':' => {
|
|
new_impl_generics.push(tt);
|
|
if in_generic {
|
|
new_impl_generics.extend(quote! { ::kernel::init::Zeroable + });
|
|
inserted = true;
|
|
}
|
|
}
|
|
TokenTree::Punct(p) if p.as_char() == '<' => {
|
|
nested += 1;
|
|
new_impl_generics.push(tt);
|
|
}
|
|
TokenTree::Punct(p) if p.as_char() == '>' => {
|
|
assert!(nested > 0);
|
|
nested -= 1;
|
|
new_impl_generics.push(tt);
|
|
}
|
|
_ => new_impl_generics.push(tt),
|
|
}
|
|
}
|
|
assert_eq!(nested, 0);
|
|
if in_generic && !inserted {
|
|
new_impl_generics.extend(quote! { : ::kernel::init::Zeroable });
|
|
}
|
|
quote! {
|
|
::kernel::__derive_zeroable!(
|
|
parse_input:
|
|
@sig(#(#rest)*),
|
|
@impl_generics(#(#new_impl_generics)*),
|
|
@ty_generics(#(#ty_generics)*),
|
|
@body(#last),
|
|
);
|
|
}
|
|
}
|