"Alternatively, use the pre-vendored rustc-src dist component" is confusing

[catamorphism]

Code

While logged in as root on Linux::

1. Clone the Rust repo
2. cd rust; ./x.py build

Current output

info: looks like you're trying to run this command as root
      and so in order to preserve your $HOME this will now
      use vendored sources by default.
error: vendoring required, but vendor directory does not exist.
       Run `cargo vendor --sync ./src/tools/rust-analyzer/Cargo.toml --sync ./compiler/rustc_codegen_cranelift/Cargo.toml --sync ./src/bootstrap/Cargo.toml ` to initialize the vendor directory.
Alternatively, use the pre-vendored `rustc-src` dist component.
Traceback (most recent call last):
  File "/home/scratch/rust/./x.py", line 29, in <module>
    bootstrap.main()
  File "/home/scratch/rust/src/bootstrap/bootstrap.py", line 949, in main
    bootstrap(args)
  File "/home/scratch/rust/src/bootstrap/bootstrap.py", line 896, in bootstrap
    build.check_vendored_status()
  File "/home/scratch/rust/src/bootstrap/bootstrap.py", line 831, in check_vendored_status
    raise Exception("{} not found".format(vendor_dir))
Exception: /home/scratch/rust/vendor not found

Desired output

The suggestion to run cargo vendor isn't helpful if you don't already have a Rust toolchain installed. That leaves: "Alternatively, use the pre-vendored rustc-src dist component." It's completely unclear to me what this means or how to do it. Perhaps providing a link to documentation would be useful.

[jyn514]

Oh this is very funny, rustc-src is what rustup calls it, which is of course completely unhelpful in this scenario where you don't have rustup and are building from source.

Mentoring instructions:

rust/src/bootstrap/bootstrap.py

Line 830 in b56fcb1

print('Alternatively, use the pre-vendored `rustc-src` dist component.')

should link to https://forge.rust-lang.org/infra/other-installation-methods.html#source-code.

[jyn514]

Hmm, I guess for this particular scenario you might be building from a commit other than latest master as well. We do technically package it for individual commits:

; curl -I https://ci-artifacts.rust-lang.org/rustc-builds/dd2b19539ea4d62a150cf13d45942e58b6b44e54/rustc-nightly-src.tar.xz | head -n1
HTTP/2 200 

but AFAIK that isn't documented anywhere. Maybe we should add it to forge?

[reez12g]

@rustbot claim

[MoskalykA]

hello, i'm taking the liberty of claiming this pull request, but I'd like some information. Should I propose a solution (like the curl command with the right url?) or just propose the documentation page?

[MoskalykA]

@rustbot claim

[seqre]

@rustbot claim