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, 16 insertions, 0 deletions

diff --git a/rust/pin-init/internal/src/lib.rs b/rust/pin-init/internal/src/lib.rs
index 3146da5cc47cc..c201b8a53915e 100644
--- a/rust/pin-init/internal/src/lib.rs
+++ b/rust/pin-init/internal/src/lib.rs
@@ -4,6 +4,22 @@
 // and thus add a dependency on `include/config/RUSTC_VERSION_TEXT`, which is
 // touched by Kconfig when the version string from the compiler changes.
 
+//! `pin-init` proc macros.
+
+#![cfg_attr(not(RUSTC_LINT_REASONS_IS_STABLE), feature(lint_reasons))]
+
+use proc_macro::TokenStream;
+
+#[cfg(kernel)]
+#[path = "../../../macros/quote.rs"]
+#[macro_use]
+mod quote;
+
+mod helpers;
+mod pin_data;
+mod pinned_drop;
+mod zeroable;
+
 #[allow(missing_docs)]
 #[proc_macro_attribute]
 pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream {