On Fri Jan 16, 2026 at 11:54 AM CET, Benno Lossin wrote:
> Rewrite the proc-macros of pin-init by using the `syn` crate for Rust
> syntax parsing. This series has been a long way coming. At the very
> start of pin-init, I initially implemented everything using syn, since
> parsing is so much easier with it. Now after several years it is finally
> time to remove the dreaded 1600 lines of declarative macros required to
> parse and expand the initializer syntax.
>
> The move to syn is not only a blessing for the maintenance work, but
> also improves the implementation of new features. This series includes
> many such improvements.
>
> * Patch 1, 2, 3 and 4 prepare for the rewrite. The first removes the
> superfluous `try_` variants of the initializer macros from pin-init.
> Note that the kernel defines its own, so no code changes in the kernel
> are required. The second patch allows using `::pin_init` in the
> pin-init crate. The third adds the syn dependency and cleans up some
> old workarounds and new clippy warnings. The fourth adds better error
> handling on top of `syn`.
> * Patch 5, 6, 7, and 9 rewrite the derive macros for Zeroable,
> `#[pinned_drop]` attribute macro, `#[pin_data]` attribute macro, and
> the initializer macros respectively using `syn`.
> * Patch 8 ensures soundness in the future by fixing generic bounds in
> generated code by `#[pin_data]`.
> * Patch 10 adds the `#[default_error(type)]` attribute to initializer
> macros allowing them to specify a default error that is used when no
> error is manually specified.
> * Patch 11 uses `#[default_error(type)]` in the definition of the
> kernel's `try_` variants of the initializer macros (which defaults to
> the kernel's `Error` type).
> * Patch 12 allows putting attributes on fields in initializer macros
> (for example `cfg` attributes).
> * Patch 13 adds `#[disable_initialized_field_access]` to support packed
> structs.
> * Patch 14 simplifies the code generated by the initializer macros.
> * Patch 15 adds Gary as a maintainer.
>
> In addition to the new features, using syn results in much cleaner error
> messages and more accurate span information. The code is much easier to
> read as well and hopefully easier to understand as well.
>
> As always, tests that ensure the correctness of the macro output are
> included and updated in the upstream pin-init repository. Take a look at
> the pull request on GitHub for the diff in the test output:
>
> https://github.com/Rust-for-Linux/pin-init/pull/89
>
> I would greatly appreciate Tested-by's from people actively using
> pin-init weather in the kernel or outside.
>
> The commit adding syn support to pin-init is also used by Gary's series
> to rewrite the `macros` crate using `syn`:
>
> https://lore.kernel.org/all/20260112170919.1888584-1-gary@kernel.org
>
> My series can be found at:
>
> https://github.com/BennoLossin/linux/commits/pin-init/sync
>
> The rust-dev branch in the RfL repository will be updated to contain
> both patch series for ease of use & testing.
>
> Link to previous versions:
>
> - v3: https://lore.kernel.org/all/20260114181934.1782470-1-lossin@kernel.org
> - v2: https://lore.kernel.org/all/20260111122554.2662175-1-lossin@kernel.org
> - v1: https://lore.kernel.org/all/20260108135127.3153925-1-lossin@kernel.org
>
> Cheers,
> Benno
>
>
> Benno Lossin (15):
> rust: pin-init: remove `try_` versions of the initializer macros
> rust: pin-init: allow the crate to refer to itself as `pin-init` in
> doc tests
> rust: pin-init: add `syn` dependency and remove `proc-macro[2]` and
> `quote` workarounds
> rust: pin-init: internal: add utility API for syn error handling
> rust: pin-init: rewrite `derive(Zeroable)` and `derive(MaybeZeroable)`
> using `syn`
> rust: pin-init: rewrite the `#[pinned_drop]` attribute macro using
> `syn`
> rust: pin-init: rewrite `#[pin_data]` using `syn`
> rust: pin-init: add `?Sized` bounds to traits in `#[pin_data]` macro
> rust: pin-init: rewrite the initializer macros using `syn`
> rust: pin-init: add `#[default_error(<type>)]` attribute to
> initializer macros
> rust: init: use `#[default_error(err)]` for the initializer macros
> rust: pin-init: internal: init: add support for attributes on
> initializer fields
> rust: pin-init: internal: init: add escape hatch for referencing
> initialized fields
> rust: pin-init: internal: init: simplify Zeroable safety check
> MAINTAINERS: add Gary Guo to pin-init
Applied to pin-init-next, thanks everyone!
Cheers,
Benno
> MAINTAINERS | 1 +
> rust/Makefile | 16 +-
> rust/kernel/init.rs | 40 +-
> rust/pin-init/README.md | 2 +-
> rust/pin-init/examples/linked_list.rs | 19 +-
> rust/pin-init/examples/pthread_mutex.rs | 10 +-
> rust/pin-init/internal/src/diagnostics.rs | 30 +
> rust/pin-init/internal/src/helpers.rs | 152 --
> rust/pin-init/internal/src/init.rs | 548 +++++++
> rust/pin-init/internal/src/lib.rs | 48 +-
> rust/pin-init/internal/src/pin_data.rs | 615 ++++++--
> rust/pin-init/internal/src/pinned_drop.rs | 88 +-
> rust/pin-init/internal/src/zeroable.rs | 157 +-
> rust/pin-init/src/lib.rs | 173 +--
> rust/pin-init/src/macros.rs | 1677 ---------------------
> scripts/generate_rust_analyzer.py | 2 +-
> 16 files changed, 1278 insertions(+), 2300 deletions(-)
> create mode 100644 rust/pin-init/internal/src/diagnostics.rs
> delete mode 100644 rust/pin-init/internal/src/helpers.rs
> create mode 100644 rust/pin-init/internal/src/init.rs
> delete mode 100644 rust/pin-init/src/macros.rs
>
>
> base-commit: 9448598b22c50c8a5bb77a9103e2d49f134c9578