Can't build nightly with 1.81.0 beta: error: feature `c_unwind` no longer requires an attribute to enable

[awilfox]

I tried this code:

LLVM_LINK_SHARED=1 \
        RUST_BACKTRACE=1 \
        python3 x.py dist -j 64

I expected to see this happen: a successful build of Rust nightly (1ddedba)

Instead, this happened:

error: the feature `c_unwind` has been stable since 1.81.0 and no longer requires an attribute to enable

Meta

rustc --version --verbose:

rustc 1.81.0-beta.2 (08328a323 2024-07-25) (Adélie 1.81.0_beta20240725-r0 [BETA])
binary: rustc
commit-hash: 08328a323ecd80b443a8fcc72c6b1071f48e233f
commit-date: 2024-07-25
host: powerpc64-unknown-linux-musl
release: 1.81.0-beta.2
LLVM version: 18.1.8

Full error

error: the feature `c_unwind` has been stable since 1.81.0 and no longer requires an attribute to enable
   --> library/core/src/lib.rs:195:32
    |
195 | #![cfg_attr(bootstrap, feature(c_unwind))]
    |                                ^^^^^^^^
    |
    = note: `-D stable-features` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(stable_features)]`

error: using `#![feature(effects)]` without enabling next trait solver globally
  |
  = note: the next trait solver must be enabled globally for the effects feature to work correctly
  = help: use `-Znext-solver` to enable

`config.toml`

[build]
build-stage = 2
test-stage = 2
build = "powerpc64-unknown-linux-musl"
host = [ "powerpc64-unknown-linux-musl" ]
target = [ "powerpc64-unknown-linux-musl" ]
cargo = "/usr/bin/cargo"
rustc = "/usr/bin/rustc"
rustfmt = "/usr/bin/rustfmt"
docs = false
compiler-docs = false
submodules = true
python = "python3"
locked-deps = true
vendor = true
extended = true
tools = [ "analysis", "cargo", "clippy", "rustfmt", "src" ]
verbose = 1
sanitizers = false
profiler = false
cargo-native-static = false
optimized-compiler-builtins = false
[install]
prefix = "/opt/rust-nightly"
[rust]
optimize = true
debug = true
codegen-units = 1
debuginfo-level = 2
debuginfo-level-rustc = 0
debuginfo-level-tests = 0
backtrace = true
incremental = false
parallel-compiler = true
channel = "nightly"
description = "Adélie 1.82.0 EXPERIMENTAL"
rpath = false
verbose-tests = true
optimize-tests = true
codegen-tests = true
dist-src = false
lld = false
use-lld = false
llvm-tools = false
backtrace-on-ice = true
remap-debuginfo = false
jemalloc = false
llvm-libunwind = "no"
new-symbol-mangling = true
[target.powerpc64-unknown-linux-musl]
cc = "powerpc64-foxkit-linux-musl-gcc"
cxx = "powerpc64-foxkit-linux-musl-g++"
ar = "ar"
ranlib = "ranlib"
linker = "powerpc64-foxkit-linux-musl-gcc"
llvm-config = "/usr/lib/llvm18/bin/llvm-config"
crt-static = false
[dist]
src-tarball = false
compression-formats = [ "xz" ]

[compiler-errors]

The bootstrap compiler has just been bumped. You should update your rustc checkout to after #128083.

[awilfox]

Confirmed, #128083 fixed it.