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rust: pin-init: internal: pin_data: move projection struct into const _: () block

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Most users would not need to mention the generated projection struct. With
the upcoming self-referential support, there needs to be additional
projection structs. Instead of give them publicly visible names, simply
make the name not publicly accessible.

A heavy user of pin projection outside kernel is for async programming.
I've checked tokio codebase there is a single use case and that's for
enums.

Acked-by: Benno Lossin <lossin@kernel.org>
Link: https://patch.msgid.link/20261006-dev-selfref-dep-v1-5-da716f740d6d@garyguo.net
Signed-off-by: Gary Guo <gary@garyguo.net>
This commit is contained in:
Gary Guo 2026-10-06 17:29:35 +02:00
parent 003a8953d2
commit 6fbdebfeb0
1 changed files with 6 additions and 7 deletions
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13
rust/pin-init/internal/src/pin_data.rs
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@ -186,10 +186,10 @@ pub(crate) fn pin_data(
Ok(quote! {
#struct_
#projections
// We put the rest into this const item, because it then will not be accessible to anything
// outside.
const _: () = {
#projections
#the_pin_data
#unpin_impl
#drop_impl
@ -322,7 +322,6 @@ fn generate_projections(
let (impl_generics, ty_generics, whr) = generics.split_for_impl();
let (_, ty_generics_with_pin_lt, _) = generics_with_pin_lt.split_for_impl();
let projection = format_ident!("{ident}Projection");
let this = format_ident!("this");
let (fields_decl, fields_proj): (Vec<_>, Vec<_>) = fields
@ -371,13 +370,13 @@ fn generate_projections(
let (projection_def, projection_init) = if is_tuple_struct {
(
quote! {
#vis struct #projection #generics_with_pin_lt (
#vis struct __Projection #generics_with_pin_lt (
#(#fields_decl)*
::core::marker::PhantomData<&'__pin mut ()>,
) #whr;
},
quote! {
#projection(
__Projection(
#(#fields_proj)*
::core::marker::PhantomData,
)
@ -386,7 +385,7 @@ fn generate_projections(
} else {
(
quote! {
#vis struct #projection #generics_with_pin_lt
#vis struct __Projection #generics_with_pin_lt
#whr
{
#(#fields_decl)*
@ -394,7 +393,7 @@ fn generate_projections(
}
},
quote! {
#projection {
__Projection {
#(#fields_proj)*
___pin_phantom_data: ::core::marker::PhantomData,
}
@ -422,7 +421,7 @@ impl #impl_generics #ident #ty_generics
#[inline]
#vis fn project<'__pin>(
self: ::core::pin::Pin<&'__pin mut Self>,
) -> #projection #ty_generics_with_pin_lt {
) -> __Projection #ty_generics_with_pin_lt {
// SAFETY: we only give access to `&mut` for fields not structurally pinned.
let #this = unsafe { ::core::pin::Pin::get_unchecked_mut(self) };
#projection_init