build: bootstrap fails when using --enable-local-rust option

[filnet]

Issue

Building rust with the --enable-local-rust option fails with a symbolic link creation error.

Reverting 6f0fc2f fixes the issue.

Version it worked on

It most recently worked on: Rust 1.67.1

Version with regression

Rust 1.68.0

Backtrace

Backtrace

thread 'main' panicked at 'symlink_dir(C:\M\mingw-w64-rust\src\MINGW64\build\host => C:\M\mingw-w64-rust\src\MINGW64\build\x86_64-pc-windows-gnu) failed with Le fichier spécifié est introuvable. (os error 2)', lib.rs:599:17
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: bootstrap::Build::new
             at C:\M\mingw-w64-rust\src\rustc-1.68.0-src\src\bootstrap\lib.rs:599:17
   3: bootstrap::main
             at C:\M\mingw-w64-rust\src\rustc-1.68.0-src\src\bootstrap\bin\main.rs:50:5
   4: core::ops::function::FnOnce::call_once
             at C:\M\mingw-w64-rust\src\rustc-1.67.1-src\library\core\src\ops\function.rs:507:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Build completed unsuccessfully in 0:00:32

[Teapot4195]

@rustbot label +t-bootstrap

Edit: how very convenient, wasn't even aware there was limitations on label, either way, does this issue occur with x86_64-windows-msvc.

[rustbot]

Error: Label t-bootstrap can only be set by Rust team members

Please file an issue on GitHub at triagebot if there's a problem with this bot, or reach out on #t-infra on Zulip.

[filnet]

does this issue occur with x86_64-windows-msvc.

I am one of the maintainers of the Rust build at https://www.msys2.org/.

The upgrade from 1.67.1 to 1.68.0 broke the aarch64 build (which uses the --enable-local-rust option).
We can also reproduce it on other architectures and tool chains.

[jyn514]

I ... don't see how this could be related to --enable-local-rust? we're not modifying anything in the stage 0 directory, only in the build directory. do you still see this issue if you remove that option?

[jyn514]

oh I see, when that option is enabled bootstrap.py doesn't download the toolchain and so there's no x86_64-pc-windows-gnu folder yet. the correct fix is to add create_dir_all(&build_triple) just after

rust/src/bootstrap/lib.rs

Line 497 in 8efa635

let build_triple = build.out.join(&build.build.triple);

[filnet]

I ... don't see how this could be related to --enable-local-rust? we're not modifying anything in the stage 0 directory, only in the build directory. do you still see this issue if you remove that option?

Using --enable-local-rust will skip downloading and extracting the previous Rust version.
The new code tries to create a symlink from host to a directory that was supposedly extracted (but was not).

There is the same issue with --local-rust-root btw.

[mu001999]

@rustbot claim