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5: Determine the visibility based on the original type r=taiki-e a=taiki-e

The visibility of the projected type and projection method is based on
the original type. However, if the visibility of the original type is
`pub`, the visibility of the projected type and the projection method is
`pub(crate)`.

Based on taiki-e/pin-project#96

Co-authored-by: Taiki Endo <[email protected]>
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@bors @taiki-e
bors[bot] and taiki-e authored Nov 15, 2019
2 parents 63dbc3d + f5dc069 commit 5b7bbcf
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Showing 3 changed files with 106 additions and 13 deletions.
2 changes: 0 additions & 2 deletions Cargo.toml
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,6 @@ A lightweight version of pin-project written with declarative macros.
[workspace]
members = ["tests/doc"]

[dependencies]

[dev-dependencies]
rustversion = "1.0"
trybuild = "1.0"
97 changes: 86 additions & 11 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,10 @@
/// # }
/// ```
///
/// The visibility of the projected type and projection method is based on the
/// original type. However, if the visibility of the original type is `pub`,
/// the visibility of the projected type and the projection method is `pub(crate)`.
///
/// If you want to call the `project` method multiple times or later use the
/// original Pin type, it needs to use [`.as_mut()`][`Pin::as_mut`] to avoid
/// consuming the `Pin`.
Expand Down Expand Up @@ -137,26 +141,98 @@
/// [`Pin::as_mut`]: core::pin::Pin::as_mut
#[macro_export]
macro_rules! pin_project {
// determine_visibility
(
$(#[$attrs:meta])*
pub struct $ident:ident
$(<
$( $lifetime:lifetime ),* $(,)?
$( $generics:ident $(: $generics_bound:path)? ),* $(,)?
>)?
$(where
$($where_clause_ty:ty : $where_clause_bound:path),* $(,)?
)?
{
$(
$(#[$pin:ident])?
$field_vis:vis $field:ident: $field_ty:ty
),+ $(,)?
}
) => {
$crate::pin_project! {@internal (pub(crate))
$(#[$attrs])*
pub struct $ident
$(<
$( $lifetime ),*
$( $generics $(: $generics_bound)? ),*
>)?
$(where
$($where_clause_ty : $where_clause_bound),*
)?
{
$(
$(#[$pin])?
$field_vis $field: $field_ty
),+
}
}
};
(
$(#[$attrs:meta])*
$vis:vis struct $ident:ident
$(<
$( $lifetime:lifetime ),* $(,)?
$( $generics:ident $(: $generics_bound:path)? ),* $(,)?
>)?
$(where
$($where_clause_ty:ty : $where_clause_bound:path),* $(,)?
)?
{
$(
$(#[$pin:ident])?
$field_vis:vis $field:ident: $field_ty:ty
),+ $(,)?
}
) => {
$crate::pin_project! {@internal ($vis)
$(#[$attrs])*
$vis struct $ident
$(<
$( $lifetime ),*
$( $generics $(: $generics_bound)? ),*
>)?
$(where
$($where_clause_ty : $where_clause_bound),*
)?
{
$(
$(#[$pin])?
$field_vis $field: $field_ty
),+
}
}
};

(@internal ($proj_vis:vis)
// limitation: does not support tuple structs and enums (wontfix)
// limitation: no projection helper (wontfix)
$(#[$attrs:meta])*
$vis:vis struct $ident:ident
$(<
$( $lifetime:lifetime ),* $(,)?
$( $lifetime:lifetime ),*
// limitation: does not support multiple bounds and ? bounds.
$( $generics:ident $(: $generics_bound:path)? ),* $(,)?
$( $generics:ident $(: $generics_bound:path)? ),*
>)?
$(where
// limitation: does not support multiple bounds and ? bounds.
$($where_clause_ty:ty : $where_clause_bound:path),* $(,)?
$($where_clause_ty:ty : $where_clause_bound:path),*
)?
{
$(
// limitation: cannot interoperate with other attributes.
$(#[$pin:ident])?
$field_vis:vis $field:ident: $field_ty:ty
),+ $(,)?
),+
}
) => {
$(#[$attrs])*
Expand All @@ -175,25 +251,25 @@ macro_rules! pin_project {
const _: () = {
#[allow(clippy::mut_mut)] // This lint warns `&mut &mut <ty>`.
#[allow(dead_code)] // This lint warns unused fields/variants.
struct Projection
$proj_vis struct Projection
<'__pin $(, $($lifetime,)* $($generics $(: $generics_bound)? ),* )?>
$(where
$($where_clause_ty: $where_clause_bound),*
)*
{
$(
$field: $crate::pin_project!(@make_proj_field $(#[$pin])? $field_ty; mut)
$field_vis $field: $crate::pin_project!(@make_proj_field $(#[$pin])? $field_ty; mut)
),+
}
#[allow(dead_code)] // This lint warns unused fields/variants.
struct ProjectionRef
$proj_vis struct ProjectionRef
<'__pin $(, $($lifetime,)* $($generics $(: $generics_bound)? ),* )?>
$(where
$($where_clause_ty: $where_clause_bound),*
)*
{
$(
$field: $crate::pin_project!(@make_proj_field $(#[$pin])? $field_ty;)
$field_vis $field: $crate::pin_project!(@make_proj_field $(#[$pin])? $field_ty;)
),+
}

Expand All @@ -203,8 +279,7 @@ macro_rules! pin_project {
$($where_clause_ty: $where_clause_bound),*
)*
{
// limitation: does not support pub(crate) fn project (wontfix)
fn project<'__pin>(
$proj_vis fn project<'__pin>(
self: ::core::pin::Pin<&'__pin mut Self>,
) -> Projection<'__pin $(, $($lifetime,)* $($generics),* )?> {
unsafe {
Expand All @@ -216,7 +291,7 @@ macro_rules! pin_project {
}
}
}
fn project_ref<'__pin>(
$proj_vis fn project_ref<'__pin>(
self: ::core::pin::Pin<&'__pin Self>,
) -> ProjectionRef<'__pin $(, $($lifetime,)* $($generics),* )?> {
unsafe {
Expand Down
20 changes: 20 additions & 0 deletions tests/test.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -212,6 +212,26 @@ fn lifetime_project_elided() {
}
}

mod visibility {
use pin_project_lite::pin_project;

pin_project! {
pub(crate) struct A {
pub b: u8,
}
}
}

#[test]
fn visibility() {
let mut x = visibility::A { b: 0 };
let x = Pin::new(&mut x);
let y = x.as_ref().project_ref();
let _: &u8 = y.b;
let y = x.project();
let _: &mut u8 = y.b;
}

#[test]
fn trivial_bounds() {
pin_project! {
Expand Down

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