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

[Tamir Duberstein]

On Tue, Mar 25, 2025 at 6:37 AM Benno Lossin <benno.lossin@xxxxxxxxx> wrote:
>
> On Tue Mar 25, 2025 at 10:52 AM CET, Tamir Duberstein wrote:
> > On Tue, Mar 25, 2025 at 12:02 AM Boqun Feng <boqun.feng@xxxxxxxxx> wrote:
> >> On Mon, Mar 24, 2025 at 05:56:57PM -0400, Tamir Duberstein wrote:
> >> > On Mon, Mar 24, 2025 at 5:51 PM Tamir Duberstein <tamird@xxxxxxxxx> wrote:
> >> > > On Mon, Mar 24, 2025 at 5:42 PM Boqun Feng <boqun.feng@xxxxxxxxx> wrote:
> >> > > > On Mon, Mar 24, 2025 at 05:33:45PM -0400, Tamir Duberstein wrote:
> >> > > > >              #[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
> >>
> >> Why impl_has_list_links uses generics at `ident` but rest use `tt`? I'm
> >> a bit curious.
> >
> > I think it's because `ident` cannot deal with lifetimes or const
> > generics - or at least I was not able to make it work with them.
>
> If you use `ident`, you can use the normal `<>` as the delimiters of
> generics. For `tt`, you have to use `{}` (or `()`/`[]`).

Yes I know. But with `ident` you cannot capture lifetimes or const generics.