[PATCH v2 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:

  - A few cleanups that can be performed before the bumps.
  - The Rust bump (and its cleanups).
  - The `bindgen` bump (and its 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]
---
v1: https://lore.kernel.org/rust-for-linux/20260401114540.30108-1-ojeda@kernel.org/
v2:
  - Added patch to globally allow `incompatible_msrv` and removed the
    last instance.

  - Replaced `--remap-path-prefix` patches with one that drops the
    workaround entirely (and place it as the first one) and summarizes
    the discussion.

    I also noticed that `--remap-path-prefix` for `rustdoc` is still
    unstable (unlike `rustc`'s one), so I added it to our list as usual
    (https://github.com/Rust-for-Linux/linux/issues/2). There does not
    seem to be a tracking issue, so I asked upstream about it.

    We will need these two lines as the resolution for the conflict:

        $(RUSTDOC) $(filter-out $(skip_flags) --remap-path-scope=%,$(if $(rustdoc_host),$(rust_common_flags),$(rust_flags))) \

        $(RUSTDOC) --test $(filter-out --remap-path-scope=%,$(rust_flags)) \

  - Reworked the `extract_if` patch to use it (unstably). The feature
    last major change happened in Rust 1.85.0, so that is fine.

  - Moved `$(HOSTRUSTFLAGS)` below so that per-version flags (like
    lints) can be overridden too. Please see the details in the commit
    and my reply to v1.

  - Added `feature(extract_if)` and `feature(non_null_convenience)`
    items to https://github.com/Rust-for-Linux/linux/issues/1223.

    Then reworded the commits accordingly to include the references
    to tracking issues and PRs.

  - Other rewords, e.g. the "beyond" typo.

  - Rebased on top of `rust-next`.

  - Picked up tags.

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

Miguel Ojeda (32):
  rust: kbuild: remove `--remap-path-prefix` workarounds
  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`
  rust: bump Rust minimum supported version to 1.85.0 (Debian Trixie)
  rust: bump Clippy's MSRV and clean `incompatible_msrv` allows
  rust: allow globally `clippy::incompatible_msrv`
  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: transmute: simplify code with Rust 1.80.0 `split_at_*checked()`
  rust: alloc: simplify with `NonNull::add()` now that it is stable
  rust: macros: simplify code using `feature(extract_if)`
  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 `bindgen` 0.66.[01]
  rust: rust_is_available: remove warning for `bindgen` < 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
  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                                      | 12 +++-
 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                                 | 31 ++--------
 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/helpers.rs                        |  1 -
 rust/macros/kunit.rs                          |  9 +--
 rust/macros/lib.rs                            |  3 +
 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 +------------------
 39 files changed, 83 insertions(+), 451 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


base-commit: 36f5a2b09e650b82d7b2a106e3b93af48c2010d9
--
2.53.0