Messages in this thread Patch in this message | | | Date | Sun, 6 Aug 2023 17:07:51 +0100 | From | Gary Guo <> | Subject | Re: [PATCH v3 09/13] rust: init: add support for arbitrary paths in init macros |
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On Sat, 29 Jul 2023 09:10:16 +0000 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 > using the `paste!` proc macro. It does not actually modify the input, > since no `[< >]` will be present in the input, so it just strips the > information held by declarative macros. 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 `paste!`, then it parses as expected. > > Suggested-by: Asahi Lina <lina@asahilina.net> > Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> > Reviewed-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
> --- > v2 -> v3: > - added Reviewed-by's from Martin and Alice. > > v1 -> v2: > - use Gary's `paste!` macro instead of `retokenize`, > - remove the retokenize macro. > > rust/kernel/init/macros.rs | 54 ++++++++++++++++++++++++-------------- > 1 file changed, 35 insertions(+), 19 deletions(-) > > diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs > index 4c86281301d8..d54243cd3c82 100644 > --- a/rust/kernel/init/macros.rs > +++ b/rust/kernel/init/macros.rs > @@ -1000,7 +1000,7 @@ 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` > @@ -1014,7 +1014,7 @@ 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)?), > @@ -1025,7 +1025,7 @@ 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` > @@ -1039,7 +1039,7 @@ 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)?), > @@ -1050,7 +1050,7 @@ 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` > @@ -1064,7 +1064,7 @@ macro_rules! __init_internal { > ) => { > $crate::__init_internal!( > @this($($this)?), > - @typ($t $(::<$($generics),*>)? ), > + @typ($t), > @fields($($fields)*), > @error($err), > @data($data, $($use_data)?), > @@ -1075,7 +1075,7 @@ 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` > @@ -1094,7 +1094,11 @@ macro_rules! __init_internal { > // Get the data about fields from the supplied type. > let data = unsafe { > use $crate::init::__internal::$has_data; > - $t$(::<$($generics),*>)?::$get_data() > + // Here we abuse `paste!` to retokenize `$t`. Declarative macros have some internal > + // information that is associated to already parsed fragments, so a path fragment > + // cannot be used in this position. Doing the retokenization results in valid rust > + // code. > + ::kernel::macros::paste!($t::$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>( > @@ -1253,7 +1257,7 @@ fn assert_zeroable<T: $crate::init::Zeroable>(_: *mut T) {} > }; > (make_initializer: > @slot($slot:ident), > - @type_name($t:ident), > + @type_name($t:path), > @munch_fields(..Zeroable::zeroed() $(,)?), > @acc($($acc:tt)*), > ) => { > @@ -1270,15 +1274,21 @@ fn assert_zeroable<T: $crate::init::Zeroable>(_: *mut T) {} > // not get executed, so it has no effect. > ::core::ptr::write($slot, zeroed); > zeroed = ::core::mem::zeroed(); > - ::core::ptr::write($slot, $t { > - $($acc)* > - ..zeroed > - }); > + // Here we abuse `paste!` to retokenize `$t`. Declarative macros have some internal > + // information that is associated to already parsed fragments, so a path fragment > + // cannot be used in this position. Doing the retokenization results in valid rust > + // code. > + ::kernel::macros::paste!( > + ::core::ptr::write($slot, $t { > + $($acc)* > + ..zeroed > + }); > + ); > } > }; > (make_initializer: > @slot($slot:ident), > - @type_name($t:ident), > + @type_name($t:path), > @munch_fields($(,)?), > @acc($($acc:tt)*), > ) => { > @@ -1286,14 +1296,20 @@ fn assert_zeroable<T: $crate::init::Zeroable>(_: *mut T) {} > // Since we are in the closure that is never called, this will never get executed. > // We abuse `slot` to get the correct type inference here: > unsafe { > - ::core::ptr::write($slot, $t { > - $($acc)* > - }); > + // Here we abuse `paste!` to retokenize `$t`. Declarative macros have some internal > + // information that is associated to already parsed fragments, so a path fragment > + // cannot be used in this position. Doing the retokenization results in valid rust > + // code. > + ::kernel::macros::paste!( > + ::core::ptr::write($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)*), > ) => { > @@ -1306,7 +1322,7 @@ fn assert_zeroable<T: $crate::init::Zeroable>(_: *mut T) {} > }; > (make_initializer: > @slot($slot:ident), > - @type_name($t:ident), > + @type_name($t:path), > @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), > @acc($($acc:tt)*), > ) => {
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