rust: make pin-init its own crate

Rename relative paths inside of the crate to still refer to the same
items, also rename paths inside of the kernel crate and adjust the build
system to build the crate.

[ Remove the `expect` (and thus the `lint_reasons` feature) since
  the tree now uses `quote!` from `rust/macros/export.rs`. Remove the
  `TokenStream` import removal, since it is now used as well.

  In addition, temporarily (i.e. just for this commit) use an `--extern
  force:alloc` to prevent an unknown `new_uninit` error in the `rustdoc`
  target. For context, please see a similar case in:

      https://lore.kernel.org/lkml/20240422090644.525520-1-ojeda@kernel.org/

  And adjusted the message above. - Miguel ]

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250308110339.2997091-16-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 29 insertions, 17 deletions

diff --git a/rust/pin-init/src/lib.rs b/rust/pin-init/src/lib.rs
index 5f1afd3abb56..41bfb35c7a2c 100644
--- a/rust/pin-init/src/lib.rs
+++ b/rust/pin-init/src/lib.rs
@@ -209,9 +209,21 @@
 //! [`impl PinInit<Foo>`]: PinInit
 //! [`impl PinInit<T, E>`]: PinInit
 //! [`impl Init<T, E>`]: Init
-//! [`pin_data`]: ::macros::pin_data
+//! [`pin_data`]: crate::pin_data
 //! [`pin_init!`]: crate::pin_init!
 
+#![cfg_attr(not(RUSTC_LINT_REASONS_IS_STABLE), feature(lint_reasons))]
+#![cfg_attr(
+    all(
+        any(feature = "alloc", feature = "std"),
+        not(RUSTC_NEW_UNINIT_IS_STABLE)
+    ),
+    feature(new_uninit)
+)]
+#![forbid(missing_docs, unsafe_op_in_unsafe_fn)]
+#![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(feature = "alloc", feature(allocator_api))]
+
 use core::{
     cell::UnsafeCell,
     convert::Infallible,
@@ -288,7 +300,7 @@ pub mod macros;
 /// ```
 ///
 /// [`pin_init!`]: crate::pin_init
-pub use ::macros::pin_data;
+pub use ::pin_init_internal::pin_data;
 
 /// Used to implement `PinnedDrop` safely.
 ///
@@ -322,7 +334,7 @@ pub use ::macros::pin_data;
 ///     }
 /// }
 /// ```
-pub use ::macros::pinned_drop;
+pub use ::pin_init_internal::pinned_drop;
 
 /// Derives the [`Zeroable`] trait for the given struct.
 ///
@@ -340,7 +352,7 @@ pub use ::macros::pinned_drop;
 ///     len: usize,
 /// }
 /// ```
-pub use ::macros::Zeroable;
+pub use ::pin_init_internal::Zeroable;
 
 /// Initialize and pin a type directly on the stack.
 ///
@@ -385,8 +397,8 @@ pub use ::macros::Zeroable;
 macro_rules! stack_pin_init {
     (let $var:ident $(: $t:ty)? = $val:expr) => {
         let val = $val;
-        let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit());
-        let mut $var = match $crate::init::__internal::StackInit::init($var, val) {
+        let mut $var = ::core::pin::pin!($crate::__internal::StackInit$(::<$t>)?::uninit());
+        let mut $var = match $crate::__internal::StackInit::init($var, val) {
             Ok(res) => res,
             Err(x) => {
                 let x: ::core::convert::Infallible = x;
@@ -463,13 +475,13 @@ macro_rules! stack_pin_init {
 macro_rules! stack_try_pin_init {
     (let $var:ident $(: $t:ty)? = $val:expr) => {
         let val = $val;
-        let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit());
-        let mut $var = $crate::init::__internal::StackInit::init($var, val);
+        let mut $var = ::core::pin::pin!($crate::__internal::StackInit$(::<$t>)?::uninit());
+        let mut $var = $crate::__internal::StackInit::init($var, val);
     };
     (let $var:ident $(: $t:ty)? =? $val:expr) => {
         let val = $val;
-        let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit());
-        let mut $var = $crate::init::__internal::StackInit::init($var, val)?;
+        let mut $var = ::core::pin::pin!($crate::__internal::StackInit$(::<$t>)?::uninit());
+        let mut $var = $crate::__internal::StackInit::init($var, val)?;
     };
 }
 
@@ -670,7 +682,7 @@ macro_rules! pin_init {
     ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
         $($fields:tt)*
     }) => {
-        $crate::_try_pin_init!($(&$this in)? $t $(::<$($generics),*>)? {
+        $crate::try_pin_init!($(&$this in)? $t $(::<$($generics),*>)? {
             $($fields)*
         }? ::core::convert::Infallible)
     };
@@ -716,7 +728,7 @@ macro_rules! pin_init {
 // For a detailed example of how this macro works, see the module documentation of the hidden
 // module `__internal` inside of `init/__internal.rs`.
 #[macro_export]
-macro_rules! _try_pin_init {
+macro_rules! try_pin_init {
     ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
         $($fields:tt)*
     }? $err:ty) => {
@@ -755,7 +767,7 @@ macro_rules! init {
     ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
         $($fields:tt)*
     }) => {
-        $crate::_try_init!($(&$this in)? $t $(::<$($generics),*>)? {
+        $crate::try_init!($(&$this in)? $t $(::<$($generics),*>)? {
             $($fields)*
         }? ::core::convert::Infallible)
     }
@@ -798,7 +810,7 @@ macro_rules! init {
 // For a detailed example of how this macro works, see the module documentation of the hidden
 // module `__internal` inside of `init/__internal.rs`.
 #[macro_export]
-macro_rules! _try_init {
+macro_rules! try_init {
     ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
         $($fields:tt)*
     }? $err:ty) => {
@@ -868,8 +880,8 @@ macro_rules! assert_pinned {
     ($ty:ty, $field:ident, $field_ty:ty, inline) => {
         let _ = move |ptr: *mut $field_ty| {
             // SAFETY: This code is unreachable.
-            let data = unsafe { <$ty as $crate::init::__internal::HasPinData>::__pin_data() };
-            let init = $crate::init::__internal::AlwaysFail::<$field_ty>::new();
+            let data = unsafe { <$ty as $crate::__internal::HasPinData>::__pin_data() };
+            let init = $crate::__internal::AlwaysFail::<$field_ty>::new();
             // SAFETY: This code is unreachable.
             unsafe { data.$field(ptr, init) }.ok();
         };
@@ -1262,7 +1274,7 @@ pub trait InPlaceWrite<T> {
 ///
 /// This trait must be implemented via the [`pinned_drop`] proc-macro attribute on the impl.
 ///
-/// [`pinned_drop`]: crate::macros::pinned_drop
+/// [`pinned_drop`]: crate::pinned_drop
 pub unsafe trait PinnedDrop: __internal::HasPinData {
     /// Executes the pinned destructor of this type.
     ///