nightly cross build started failing 2025-08-06 #145059
Description
Summary
I have a GitHub Actions workflow that cross-builds a nightly rust toolchain from x86_64-pc-windows-gnu to x86_64-pc-cygwin. On 2025-08-06, this started failing.
Command used
PKG_CONFIG_SYSROOT_DIR="$(cygpath -w /)" \
PKG_CONFIG="$(cygpath -w /usr/bin/pkgconf.exe)" \
LIBGIT2_NO_VENDOR=1 \
OPENSSL_DIR="$(cygpath -w /usr)" \
OPENSSL_LIB_DIR="$(cygpath -w /usr/lib)" \
OPENSSL_STATIC=0 \
DESTDIR="$(cygpath -w "$PWD/build-Cygwin/dest-rust")" \
python x.py install --stage 2Expected behaviour
successful build, as on 2025-08-05 and before
Actual behaviour
Building stage2 tool cargo (x86_64-pc-windows-gnu -> x86_64-pc-cygwin)
Compiling proc-macro2 v1.0.95
Compiling unicode-ident v1.0.18
Compiling libc v0.2.174
Compiling cfg-if v1.0.1
error[E0463]: can't find crate for `core`
|
= note: the `x86_64-pc-windows-gnu` target may not be installed
= help: consider downloading the target with `rustup target add x86_64-pc-windows-gnu`
= help: consider building the standard library from source with `cargo build -Zbuild-std`
error[E0463]: can't find crate for `std`
|
= note: the `x86_64-pc-windows-gnu` target may not be installed
= help: consider downloading the target with `rustup target add x86_64-pc-windows-gnu`
= help: consider building the standard library from source with `cargo build -Zbuild-std`
For more information about this error, try `rustc --explain E0463`.
Bootstrap configuration (bootstrap.toml)
# see src/bootstrap/defaults/
profile = "dist"
# see src/bootstrap/src/utils/change_tracker.rs
change-id = 138986
[build]
submodules = false
build = "x86_64-pc-windows-gnu"
host = ["x86_64-pc-cygwin"]
target = [
"x86_64-pc-cygwin",
]
build-dir = "build-Cygwin"
python = "$MSYS2_ROOT/mingw64/bin/python.exe"
locked-deps = true
vendor = true
tools = [
"clippy", "rustdoc", "rustfmt", "rust-analyzer-proc-macro-srv", "analysis",
"cargo",
]
profiler = true
docs = false
[install]
prefix = "/usr"
sysconfdir = "/etc"
[llvm]
link-shared = true
[rust]
codegen-units-std = 1
channel = "stable"
rpath = false
frame-pointers = true
llvm-bitcode-linker = false
lld = false
llvm-tools = false
codegen-tests = false
deny-warnings = false
backtrace-on-ice = true
control-flow-guard = true
lto = "thin"
[dist]
compression-formats = ["gz"]
compression-profile = "fast"
include-mingw-linker = false
[target.x86_64-pc-windows-gnu]
cc = "$MSYS2_ROOT/mingw64/bin/clang.exe"
cxx = "$MSYS2_ROOT/mingw64/bin/clang++.exe"
ar = "$MSYS2_ROOT/mingw64/bin/llvm-ar.exe"
ranlib = "$MSYS2_ROOT/mingw64/bin/llvm-ranlib.exe"
linker = "$MSYS2_ROOT/mingw64/bin/clang.exe"
llvm-config = "$MSYS2_ROOT/mingw64/bin/llvm-config.exe"
crt-static = true
[target.x86_64-pc-cygwin]
cc = "$WORKSPACE/gcc.exe"
cxx = "$WORKSPACE/g++.exe"
ar = "$WORKSPACE/ar.exe"
ranlib = "$WORKSPACE/ranlib.exe"
linker = "$WORKSPACE/x86_64-pc-cygwin-gcc.exe"
llvm-config = "$WORKSPACE/llvm-config.exe"
profiler = falseOperating system
windows-latest
HEAD
https://static.rust-lang.org/dist/2025-08-06/rustc-nightly-src.tar.xz
Additional context
https://github.com/jeremyd2019/cygwin-rust-bootstrap/actions/runs/16774967434/job/47498825933 - all the scripts and configs are in that repository.
Build Log
too long to paste, see https://github.com/jeremyd2019/cygwin-rust-bootstrap/actions/runs/16774967434/job/47498825933