Messages in this thread | | | Date | Sat, 24 Jun 2023 15:20:36 +0000 | From | Björn Roy Baron <> | Subject | Re: [PATCH 7/7] rust: init: add support for arbitrary paths in init macros |
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On Saturday, June 24th, 2023 at 11:25, Benno Lossin <benno.lossin@proton.me> wrote:
> Previously only `ident` and generic types were supported in the > `{try_}{pin_}init!` macros. This patch allows arbitrary path fragments, > so for example `Foo::Bar` but also very complex paths such as > `<Foo as Baz>::Bar::<0, i32>`. > > Internally this is accomplished by using `path` fragments. Due to some > peculiar declarative macro limitations, we have to "forget" certain > additional parsing information in the token trees. This is achieved by > the new `retokenize` proc macro. It does not modify the input, but just > strips this information. For example, if a declarative macro takes > `$t:path` as its input, it cannot sensibly propagate this to a macro that > takes `$($p:tt)*` as its input, since the `$t` token will only be > considered one `tt` token for the second macro. If we first pipe the > tokens through `retokenize`, then it parses as expected. > > Suggested-by: Asahi Lina <lina@asahilina.net> > Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
> --- > rust/kernel/init/__internal.rs | 2 ++ > rust/kernel/init/macros.rs | 42 +++++++++++++++++++--------------- > rust/macros/lib.rs | 17 +++++++++++++- > 3 files changed, 41 insertions(+), 20 deletions(-) > > diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs > index 7abd1fb65e41..e36a706a4a1b 100644 > --- a/rust/kernel/init/__internal.rs > +++ b/rust/kernel/init/__internal.rs > @@ -9,6 +9,8 @@ > > use super::*; > > +pub use ::macros::retokenize; > + > /// See the [nomicon] for what subtyping is. See also [this table]. > /// > /// [nomicon]: https://doc.rust-lang.org/nomicon/subtyping.html > diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs > index 5dcb2e513f26..6a82be675808 100644 > --- a/rust/kernel/init/macros.rs > +++ b/rust/kernel/init/macros.rs > @@ -998,7 +998,7 @@ impl<$($impl_generics)*> $pin_data<$($ty_generics)*> > macro_rules! __init_internal { > ( > @this($($this:ident)?), > - @typ($t:ident $(::<$($generics:ty),*>)?), > + @typ($t:path), > @fields($($fields:tt)*), > @error($err:ty), > // Either `PinData` or `InitData`, `$use_data` should only be present in the `PinData` > @@ -1012,7 +1012,7 @@ macro_rules! __init_internal { > ) => { > $crate::__init_internal!(with_update_parsed: > @this($($this)?), > - @typ($t $(::<$($generics),*>)? ), > + @typ($t), > @fields($($fields)*), > @error($err), > @data($data, $($use_data)?), > @@ -1023,7 +1023,7 @@ macro_rules! __init_internal { > }; > ( > @this($($this:ident)?), > - @typ($t:ident $(::<$($generics:ty),*>)?), > + @typ($t:path), > @fields($($fields:tt)*), > @error($err:ty), > // Either `PinData` or `InitData`, `$use_data` should only be present in the `PinData` > @@ -1037,7 +1037,7 @@ macro_rules! __init_internal { > ) => { > $crate::__init_internal!(with_update_parsed: > @this($($this)?), > - @typ($t $(::<$($generics),*>)? ), > + @typ($t), > @fields($($fields)*), > @error($err), > @data($data, $($use_data)?), > @@ -1048,7 +1048,7 @@ macro_rules! __init_internal { > }; > ( > @this($($this:ident)?), > - @typ($t:ident $(::<$($generics:ty),*>)?), > + @typ($t:path), > @fields($($fields:tt)*), > @error($err:ty), > // Either `PinData` or `InitData`, `$use_data` should only be present in the `PinData` > @@ -1062,7 +1062,7 @@ macro_rules! __init_internal { > ) => { > $crate::__init_internal!( > @this($($this)?), > - @typ($t $(::<$($generics),*>)? ), > + @typ($t), > @fields($($fields)*), > @error($err), > @data($data, $($use_data)?), > @@ -1073,7 +1073,7 @@ macro_rules! __init_internal { > }; > (with_update_parsed: > @this($($this:ident)?), > - @typ($t:ident $(::<$($generics:ty),*>)?), > + @typ($t:path), > @fields($($fields:tt)*), > @error($err:ty), > // Either `PinData` or `InitData`, `$use_data` should only be present in the `PinData` > @@ -1092,7 +1092,7 @@ macro_rules! __init_internal { > // Get the data about fields from the supplied type. > let data = unsafe { > use $crate::init::__internal::$has_data; > - $t$(::<$($generics),*>)?::$get_data() > + $crate::init::__internal::retokenize!($t::$get_data()) > }; > // Ensure that `data` really is of type `$data` and help with type inference: > let init = $crate::init::__internal::$data::make_closure::<_, __InitOk, $err>( > @@ -1247,7 +1247,7 @@ fn is_zeroable<T: Zeroable>(ptr: *mut T) {} > }; > (make_initializer: > @slot($slot:ident), > - @type_name($t:ident), > + @type_name($t:path), > @munch_fields(..Zeroable::zeroed() $(,)?), > @acc($($acc:tt)*), > ) => { > @@ -1263,15 +1263,17 @@ fn is_zeroable<T: Zeroable>(ptr: *mut T) {} > // not get executed, so it has no effect. > ::core::ptr::write($slot, zeroed); > zeroed = ::core::mem::zeroed(); > - ::core::ptr::write($slot, $t { > - $($acc)* > - ..zeroed > - }); > + $crate::init::__internal::retokenize!( > + ::core::ptr::write($slot, $t { > + $($acc)* > + ..zeroed > + }); > + ); > } > }; > (make_initializer: > @slot($slot:ident), > - @type_name($t:ident), > + @type_name($t:path), > @munch_fields($(,)?), > @acc($($acc:tt)*), > ) => { > @@ -1279,14 +1281,16 @@ fn is_zeroable<T: Zeroable>(ptr: *mut T) {} > // Since we are in the `if false` branch, this will never get executed. We abuse `slot` to > // get the correct type inference here: > unsafe { > - ::core::ptr::write($slot, $t { > - $($acc)* > - }); > + $crate::init::__internal::retokenize!( > + ::core::ptr::write($slot, $t { > + $($acc)* > + }); > + ); > } > }; > (make_initializer: > @slot($slot:ident), > - @type_name($t:ident), > + @type_name($t:path), > @munch_fields($field:ident <- $val:expr, $($rest:tt)*), > @acc($($acc:tt)*), > ) => { > @@ -1299,7 +1303,7 @@ fn is_zeroable<T: Zeroable>(ptr: *mut T) {} > }; > (make_initializer: > @slot($slot:ident), > - @type_name($t:ident), > + @type_name($t:path), > @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), > @acc($($acc:tt)*), > ) => { > diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs > index 9f056a5c780a..d329ab622fd4 100644 > --- a/rust/macros/lib.rs > +++ b/rust/macros/lib.rs > @@ -12,7 +12,7 @@ > mod vtable; > mod zeroable; > > -use proc_macro::TokenStream; > +use proc_macro::{Group, TokenStream, TokenTree}; > > /// Declares a kernel module. > /// > @@ -266,3 +266,18 @@ pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { > pub fn derive_zeroable(input: TokenStream) -> TokenStream { > zeroable::derive(input) > } > + > +/// Does not modify the given TokenStream, but removes any declarative macro information. > +#[proc_macro] > +pub fn retokenize(input: TokenStream) -> TokenStream { > + fn id(tt: TokenTree) -> TokenTree { > + match tt { > + TokenTree::Group(g) => TokenTree::Group(Group::new( > + g.delimiter(), > + g.stream().into_iter().map(id).collect(), > + )), > + x => x, > + } > + } > + input.into_iter().map(id).collect() > +} > -- > 2.41.0
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