rust 1.89.0 fails to bootstrap on x86_64

Hi,

This is a spinoff of #145587 . I'm encountering the same error as described there, but the difference is that I'm not doing a cross compilation.

This is the error I'm getting:

...
2025/08/19 21:50:06 WARN    Compiling build_helper v0.1.0 (/home/build/rustc-1.89.0-src/src/build_helper)
2025/08/19 21:50:22 WARN     Finished `dev` profile [unoptimized] target(s) in 24.30s
2025/08/19 21:50:23 INFO WARNING: The `change-id` is missing in the `bootstrap.toml`. This means that you will not be able to track the major changes made to the bootstrap configurations.
2025/08/19 21:50:23 INFO NOTE: to silence this warning, add `change-id = 142379` or `change-id = "ignore"` at the top of `bootstrap.toml`
2025/08/19 21:50:23 INFO Building compiler artifacts (stage0 -> stage1, x86_64-unknown-linux-gnu)
2025/08/19 21:50:24 WARN    Compiling proc-macro2 v1.0.95
2025/08/19 21:50:24 WARN    Compiling unicode-ident v1.0.18
2025/08/19 21:50:24 WARN    Compiling cfg-if v1.0.1
2025/08/19 21:50:24 WARN    Compiling libc v0.2.174
2025/08/19 21:50:24 WARN    Compiling memchr v2.7.5
2025/08/19 21:50:24 WARN    Compiling shlex v1.3.0
2025/08/19 21:50:24 WARN    Compiling stable_deref_trait v1.2.0
2025/08/19 21:50:24 WARN    Compiling smallvec v1.15.1
2025/08/19 21:50:24 WARN    Compiling bitflags v2.9.1
2025/08/19 21:50:24 WARN    Compiling foldhash v0.1.5
2025/08/19 21:50:24 WARN    Compiling once_cell v1.21.3
2025/08/19 21:50:24 WARN    Compiling equivalent v1.0.2
2025/08/19 21:50:24 WARN    Compiling allocator-api2 v0.2.21
2025/08/19 21:50:24 WARN    Compiling getrandom v0.3.3
2025/08/19 21:50:24 WARN    Compiling autocfg v1.4.0
2025/08/19 21:50:24 WARN    Compiling parking_lot_core v0.9.11
2025/08/19 21:50:24 WARN error[E0463]: can't find crate for `core`
2025/08/19 21:50:24 WARN   |
2025/08/19 21:50:24 WARN   = note: the `x86_64-unknown-linux-gnu` target may not be installed
2025/08/19 21:50:24 WARN   = help: consider downloading the target with `rustup target add x86_64-unknown-linux-gnu`
2025/08/19 21:50:24 WARN   = help: consider building the standard library from source with `cargo build -Zbuild-std`
2025/08/19 21:50:24 WARN
2025/08/19 21:50:24 WARN For more information about this error, try `rustc --explain E0463`.
2025/08/19 21:50:24 WARN error[E0463]: can't find crate for `std`
2025/08/19 21:50:24 WARN   |
2025/08/19 21:50:24 WARN   = note: the `x86_64-unknown-linux-gnu` target may not be installed
2025/08/19 21:50:24 WARN   = help: consider downloading the target with `rustup target add x86_64-unknown-linux-gnu`
2025/08/19 21:50:24 WARN   = help: consider building the standard library from source with `cargo build -Zbuild-std`
2025/08/19 21:50:24 WARN
2025/08/19 21:50:24 WARN error: could not compile `cfg-if` (lib) due to 1 previous error
2025/08/19 21:50:24 WARN warning: build failed, waiting for other jobs to finish...
2025/08/19 21:50:24 WARN error: could not compile `stable_deref_trait` (lib) due to 1 previous error
2025/08/19 21:50:24 WARN error: could not compile `smallvec` (lib) due to 1 previous error
2025/08/19 21:50:24 WARN error: could not compile `foldhash` (lib) due to 1 previous error
2025/08/19 21:50:24 WARN error: could not compile `bitflags` (lib) due to 1 previous error
2025/08/19 21:50:24 WARN error: could not compile `memchr` (lib) due to 1 previous error
2025/08/19 21:50:24 WARN error: could not compile `equivalent` (lib) due to 1 previous error
2025/08/19 21:50:24 WARN error: could not compile `once_cell` (lib) due to 1 previous error
2025/08/19 21:50:24 WARN error: could not compile `allocator-api2` (lib) due to 1 previous error
2025/08/19 21:50:25 WARN Build completed unsuccessfully in 0:00:26

Basically, we're bootstrapping rust 1.89.0 (using our own packaged rust 1.88.0). Our rust 1.89 package definition can be found here:

https://github.com/wolfi-dev/os/pull/62378/files

but I'm pasting below the full sequence of commands we're using:

# wget https://static.rust-lang.org/dist/rustc-1.88.0-src.tar.xz
# tar -xJf rustc-1.88.0-src.tar.xz
# export CFLAGS="$CFLAGS -O2 -I/usr/lib/llvm-20/include"
# export CXXFLAGS="$CXXFLAGS -O2 -I/usr/lib/llvm-20/include"
# export OPENSSL_NO_VENDOR=1
# export RUST_BACKTRACE=full
# export ARCH="x86_64-unknown-linux-gnu"
# cd rustc-1.88.0-src
# cat > config.toml << EOF
[rust]
deny-warnings = false
EOF
# ./configure \
        --host="${ARCH}" \
        --target="${ARCH}" \
        --prefix="/usr" \
        --release-channel="stable" \
        --enable-local-rust \
        --local-rust-root="/usr" \
        --llvm-root="/usr/lib/llvm-20" \
        --llvm-config="/usr/lib/llvm-20/bin/llvm-config" \
        --disable-docs \
        --enable-extended \
        --tools="cargo,src,clippy,rustfmt,rustdoc" \
        --enable-llvm-link-shared \
        --enable-option-checking \
        --enable-locked-deps \
        --enable-profiler \
        --enable-vendor \
        --dist-compression-formats=gz \
        --python="python3" \
        --set="rust.musl-root=/usr" \
        --set="rust.codegen-units=1" \
        --set="rust.codegen-units-std=1" \
        --set="target.${ARCH}.musl-root=/usr" \
        --set="target.${ARCH}.crt-static=false" \
        --set="target.${ARCH}.musl-root=/usr" \
        --set="target.${ARCH}.crt-static=false"
# sed -i '/^\[rust\]$/a lld=false' bootstrap.toml
# sed 's|deny(warnings,|deny(|' -i src/bootstrap/src/lib.rs
# export RUSTC_BOOTSTRAP=1
# DESTDIR="/something" python3 ./x.py install --jobs $(nproc)

Here's the rustc version I'm using to bootstrap:

# rustc --version
rustc 1.88.0 (6b00bc388 2025-06-23) (built from a source tarball)

As I said, this is not a cross compilation; I'm bootstrapping the package in a x86_64 machine.

Initially I thought this could be related to https://github.com/rust-lang/rust/pull/141729 and tested by reverting the commit, but that doesn't work either (I see another error).

Start with the bootstrap.toml and config.toml settings, then review src/bootstrap/src/lib.rs and the provided python3 ./x.py install command. Reproduce the x86_64-unknown-linux-gnu bootstrap using the listed Rust 1.88.0 setup and inspect the missing core/std errors. Done means identifying why the target is unavailable during the stage0-to-stage1 build and defining a verified fix.