Re: [PATCH 3/5] rust: list: use consistent type parameter names

[Tamir Duberstein <tamird@gmail.com>]

On Mon, Mar 24, 2025 at 5:42 PM Boqun Feng <boqun.feng@gmail.com> wrote:
>
> On Mon, Mar 24, 2025 at 05:33:45PM -0400, Tamir Duberstein wrote:
> > Refer to the type parameters of `impl_has_list_links{,_self_ptr}!` by
> > the same name used in `impl_list_item!`.
> >
> > Signed-off-by: Tamir Duberstein <tamird@gmail.com>
> > ---
> >  rust/kernel/list/impl_list_item_mod.rs | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/rust/kernel/list/impl_list_item_mod.rs b/rust/kernel/list/impl_list_item_mod.rs
> > index 5ed66fdce953..9d2102138c48 100644
> > --- a/rust/kernel/list/impl_list_item_mod.rs
> > +++ b/rust/kernel/list/impl_list_item_mod.rs
> > @@ -41,7 +41,7 @@ unsafe fn raw_get_list_links(ptr: *mut Self) -> *mut ListLinks<ID> {
> >  /// Implements the [`HasListLinks`] trait for the given type.
> >  #[macro_export]
> >  macro_rules! impl_has_list_links {
> > -    ($(impl$(<$($implarg:ident),*>)?
> > +    ($(impl$(<$($generics:ident),*>)?
> >         HasListLinks$(<$id:tt>)?
> >         for $self:ty
> >         { self$(.$field:ident)* }
> > @@ -51,7 +51,7 @@ macro_rules! impl_has_list_links {
> >          //
> >          // The behavior of `raw_get_list_links` is not changed since the `addr_of_mut!` macro is
> >          // equivalent to the pointer offset operation in the trait definition.
> > -        unsafe impl$(<$($implarg),*>)? $crate::list::HasListLinks$(<$id>)? for $self {
> > +        unsafe impl$(<$($generics),*>)? $crate::list::HasListLinks$(<$id>)? for $self {
> >              const OFFSET: usize = ::core::mem::offset_of!(Self, $($field).*) as usize;
> >
> >              #[inline]
> > @@ -81,16 +81,16 @@ pub unsafe trait HasSelfPtr<T: ?Sized, const ID: u64 = 0>
> >  /// Implements the [`HasListLinks`] and [`HasSelfPtr`] traits for the given type.
> >  #[macro_export]
> >  macro_rules! impl_has_list_links_self_ptr {
> > -    ($(impl$({$($implarg:tt)*})?
> > +    ($(impl$({$($generics:tt)*})?
>
> While you're at it, can you also change this to be
>
>         ($(impl$(<$($generics:tt)*>)?
>
> ?
>
> I don't know why we chose <> for impl_has_list_links, but {} for
> impl_has_list_links_self_ptr ;-)

This doesn't work in all cases:

error: local ambiguity when calling macro `impl_has_work`: multiple
parsing options: built-in NTs tt ('generics') or 1 other option.
   --> ../rust/kernel/workqueue.rs:522:11
    |
522 |     impl<T> HasWork<Self> for ClosureWork<T> { self.work }

The reason that `impl_has_list_links` uses <> and all others use {} is
that `impl_has_list_links` is the only one that captures the generic
parameter as an `ident`, the rest use `tt`. So we could change
`impl_has_list_links` to use {}, but not the other way around.