[PATCH 00/33] rust: bump minimum Rust and `bindgen` versions

[Miguel Ojeda <ojeda@kernel.org>]

As proposed in the past in e.g. LPC 2025 and the Maintainers Summit [1],
we are going to follow Debian Stable's Rust versions as our minimum
supported version.

Debian Trixie was released with a Rust 1.85.0 toolchain [2], which it
still uses to this day [3] (i.e. no update to Rust 1.85.1).

Debian Trixie was released with `bindgen` 0.71.1, which it also still
uses to this day [4].

Debian Trixie's release happened on 2025-08-09 [5], which means that a
fair amount of time has passed since its release for kernel developers
to upgrade.

Thus bump the minimum to the new versions, i.e.

  - Rust: 1.78.0 -> 1.85.0
  - bindgen: 0.65.1 -> 0.71.1

There are a few main parts to the series, in this order:

  - The Rust bump (and cleanups).
  - The bindgen bump (and cleanups).
  - Documentation updates.
  - The `cfi_encoding` patch, added here, which needs the bump.
  - The per-version flags support and a Clippy cleanup on top.

Link: https://lwn.net/Articles/1050174/ [1]
Link: https://www.debian.org/releases/trixie/release-notes/whats-new.en.html#desktops-and-well-known-packages [2]
Link: https://packages.debian.org/trixie/rustc [3]
Link: https://packages.debian.org/trixie/bindgen [4]
Link: https://www.debian.org/releases/trixie/ [5]
---
The cleanups should cover most of it -- there may be more we can do
later e.g. in linux-next.

Most patches are optional, so if there are concerns with any, they can
be dropped or be done later. Most are straightforward, though, and e.g.
a couple of them update TODO comments to keep the series even simpler.

The patches have been split as much as possible to be able to add as
much context as possible and to make it easier to review and to drop any
if needed.

All in all, it is a nice `--stat` of deletions I think :)

Alice Ryhl (1):
  rust: declare cfi_encoding for lru_status

Miguel Ojeda (32):
  rust: bump Rust minimum supported version to 1.85.0 (Debian Trixie)
  rust: bump Clippy's MSRV and clean `incompatible_msrv` allows
  rust: simplify `RUSTC_VERSION` Kconfig conditions
  rust: remove `RUSTC_HAS_SLICE_AS_FLATTENED` and simplify code
  rust: remove `RUSTC_HAS_COERCE_POINTEE` and simplify code
  rust: kbuild: remove skipping of `-Wrustdoc::unescaped_backticks`
  rust: kbuild: remove `feature(...)`s that are now stable
  rust: kbuild: simplify `--remap-path-prefix` workaround
  rust: kbuild: make `--remap-path-prefix` workaround conditional
  rust: transmute: simplify code with Rust 1.80.0 `split_at_*checked()`
  rust: alloc: simplify with `NonNull::add()` now that it is stable
  rust: macros: update `extract_if` MSRV TODO comment
  rust: block: update `const_refs_to_static` MSRV TODO comment
  rust: bump `bindgen` minimum supported version to 0.71.1 (Debian
    Trixie)
  rust: rust_is_available: remove warning for 0.66.[01] buggy versions
  rust: rust_is_available: remove warning for < 0.69.5 && libclang >=
    19.1
  rust: kbuild: update `bindgen --rust-target` version and replace
    comment
  rust: kbuild: remove "dummy parameter" workaround for `bindgen` <
    0.71.1
  rust: kbuild: remove "`try` keyword" workaround for `bindgen` < 0.59.2
  rust: kbuild: remove unneeded old `allow`s for generated layout tests
  gpu: nova-core: bindings: remove unneeded `cfg_attr`
  docs: rust: quick-start: openSUSE provides `rust-src` package nowadays
  docs: rust: quick-start: update Ubuntu versioned packages
  docs: rust: quick-start: update minimum Ubuntu version
  docs: rust: quick-start: add Ubuntu 26.04 LTS and remove subsection
    title
  docs: rust: quick-start: remove Gentoo "testing" note
  docs: rust: quick-start: remove Nix "unstable channel" note
  docs: rust: quick-start: remove GDB/Binutils mention
  docs: rust: general-information: simplify Kconfig example
  docs: rust: general-information: use real example
  rust: kbuild: support global per-version flags
  rust: kbuild: allow `clippy::precedence` for Rust < 1.86.0

 .clippy.toml                                  |  2 +-
 Documentation/process/changes.rst             |  4 +-
 Documentation/rust/general-information.rst    |  4 +-
 Documentation/rust/quick-start.rst            | 52 +++++++----------
 Makefile                                      |  9 +++
 arch/Kconfig                                  |  3 +-
 arch/arm64/Kconfig                            |  8 ---
 arch/riscv/Kconfig                            |  3 -
 drivers/android/binder/Makefile               |  3 +-
 drivers/android/binder/page_range.rs          |  6 +-
 drivers/android/binder/page_range_helper.c    | 24 --------
 drivers/android/binder/page_range_helper.h    | 15 -----
 drivers/gpu/nova-core/gsp/cmdq.rs             |  6 +-
 drivers/gpu/nova-core/gsp/fw/r570_144.rs      |  3 -
 init/Kconfig                                  | 15 +----
 rust/Makefile                                 | 36 ++++--------
 rust/bindgen_parameters                       |  8 +--
 rust/bindings/bindings_helper.h               |  1 -
 rust/bindings/lib.rs                          |  5 +-
 rust/kernel/alloc/allocator/iter.rs           |  8 +--
 rust/kernel/alloc/kbox.rs                     | 29 +---------
 rust/kernel/block/mq/gen_disk.rs              |  4 +-
 rust/kernel/lib.rs                            | 30 +---------
 rust/kernel/list/arc.rs                       | 22 +------
 rust/kernel/prelude.rs                        |  3 -
 rust/kernel/ptr.rs                            |  1 -
 rust/kernel/slice.rs                          | 49 ----------------
 rust/kernel/sync/arc.rs                       | 21 +------
 rust/kernel/transmute.rs                      | 35 ++---------
 rust/macros/kunit.rs                          |  2 +-
 rust/uapi/lib.rs                              |  5 +-
 scripts/Makefile.build                        |  6 +-
 scripts/min-tool-version.sh                   |  4 +-
 scripts/rust_is_available.sh                  | 36 +-----------
 scripts/rust_is_available_bindgen_0_66.h      |  2 -
 ...ust_is_available_bindgen_libclang_concat.h |  3 -
 scripts/rust_is_available_test.py             | 58 +------------------
 37 files changed, 79 insertions(+), 446 deletions(-)
 delete mode 100644 drivers/android/binder/page_range_helper.c
 delete mode 100644 drivers/android/binder/page_range_helper.h
 delete mode 100644 rust/kernel/slice.rs
 delete mode 100644 scripts/rust_is_available_bindgen_0_66.h
 delete mode 100644 scripts/rust_is_available_bindgen_libclang_concat.h

--
2.53.0