rust: bump Rust minimum supported version to 1.85.0 (Debian Trixie)

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's release happened on 2025-08-09 [4], 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 version.

Then, in later commits, clean up most of the workarounds and other bits
that this upgrade of the minimum allows us.

pin-init was left as-is since the patches come from upstream. And the
vendored crates are unmodified, since we do not want to change those.

Note that the minimum LLVM major version for Rust 1.85.0 is LLVM 18 (the
Rust upstream binaries use LLVM 19.1.7), thus e.g. `RUSTC_LLVM_VERSION`
tests can also be updated, but there are no suitable ones to simplify.

Ubuntu 25.10 also has a recent enough Rust toolchain [5], and they also
provide versioned packages with a Rust 1.85.1 toolchain even back to
Ubuntu 22.04 LTS [6].

Link: https://lwn.net/Articles/1050174/
Link: https://www.debian.org/releases/trixie/release-notes/whats-new.en.html#desktops-and-well-known-packages
Link: https://packages.debian.org/trixie/rustc
Link: https://www.debian.org/releases/trixie/
Link: https://packages.ubuntu.com/search?suite=all&searchon=names&keywords=rustc
Link: https://launchpad.net/ubuntu/+source/rustc-1.85
Acked-by: Tamir Duberstein <tamird@kernel.org>
Acked-by: Benno Lossin <lossin@kernel.org>
Acked-by: Gary Guo <gary@garyguo.net>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260405235309.418950-6-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
index 6b373e193548515aa8b13c49f8d29b60e3aaf7e9..474594bd483138d9b734060455eaa76e66bfa7fc 100644 (file)
--- a/Documentation/process/changes.rst
+++ b/Documentation/process/changes.rst
@@ -31,7 +31,7 @@ you probably needn't concern yourself with pcmciautils.
 ====================== ===============  ========================================
 GNU C                  8.1              gcc --version
 Clang/LLVM (optional)  15.0.0           clang --version
-Rust (optional)        1.78.0           rustc --version
+Rust (optional)        1.85.0           rustc --version
 bindgen (optional)     0.65.1           bindgen --version
 GNU make               4.0              make --version
 bash                   4.2              bash --version

diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh
index 99b5575c1ef7486e19e3bed511b70b23d1c06ff2..a270ec761f645e6b7083c265fd2e085cbce908de 100755 (executable)
--- a/scripts/min-tool-version.sh
+++ b/scripts/min-tool-version.sh
@@ -31,7 +31,7 @@ llvm)
        fi
        ;;
 rustc)
-       echo 1.78.0
+       echo 1.85.0
        ;;
 bindgen)
        echo 0.65.1