replace <commit> placeholder with the actual commit in vendoring error

[onur-ozkan]

Currently, vendoring error related to missing vendor directory is as follows:

rust/src/bootstrap/bootstrap.py

Lines 1034 to 1046 in 5ad7454

	eprint('ERROR: vendoring required, but vendor directory does not exist.')
	eprint(' Run `cargo vendor {}` to initialize the '
	'vendor directory.'.format(sync_dirs))
	eprint(' Alternatively, use the pre-vendored `rustc-src` dist component.')
	eprint(' To get a stable/beta/nightly version, download it from: ')
	eprint(' '
	'https://forge.rust-lang.org/infra/other-installation-methods.html#source-code')
	eprint(' To get a specific commit version, download it using the below URL,')
	eprint(' replacing <commit> with a specific commit checksum: ')
	eprint(' '
	'https://ci-artifacts.rust-lang.org/rustc-builds/<commit>/rustc-nightly-src.tar.xz')
	eprint(' Once you have the source downloaded, place the vendor directory')
	eprint(' from the archive in the root of the rust project.')

It would be more appropriate to replace the placeholder in the URL provided in error message with an actual commit hash (The one we use for downloading ci rustc. See fn download_ci_rustc_commit). This way, the link can be copied and used without requiring extra effort to manually replace the placeholder with the commit hash.

[carlosguealv]

I'd like to work on this

[carlosguealv]

@onur-ozkan Can you assign me to this issue please?

[onur-ozkan]

I'd like to work on this

Amazing!

@onur-ozkan Can you assign me to this issue please?

Sure, I just did. You can also claim issues using rustbot (see https://rustc-dev-guide.rust-lang.org/rustbot.html?highlight=cla#issue-claiming).

[carlosguealv]

Perfect, thank you!

[onur-ozkan]

Some instructions about what can be done for this task:

1- If source is not a git tree, leave the placeholder as is.

2- Use git to obtain the commit hash of the CI Rustc (the one we use for download-rustc config). For guidance on how to get this commit hash, there is a good reference in bootstrap/src/core/config/config.rs:

rust/src/bootstrap/src/core/config/config.rs

Lines 2294 to 2351 in 9aa232e

	fn download_ci_rustc_commit(&self, download_rustc: Option<StringOrBool>) -> Option<String> {
	// If `download-rustc` is not set, default to rebuilding.
	let if_unchanged = match download_rustc {
	None | Some(StringOrBool::Bool(false)) => return None,
	Some(StringOrBool::Bool(true)) => false,
	Some(StringOrBool::String(s)) if s == "if-unchanged" => true,
	Some(StringOrBool::String(other)) => {
	panic!("unrecognized option for download-rustc: {other}")
	}
	};
	// Handle running from a directory other than the top level
	let top_level = output(self.git().args(&["rev-parse", "--show-toplevel"]));
	let top_level = top_level.trim_end();
	let compiler = format!("{top_level}/compiler/");
	let library = format!("{top_level}/library/");
	// Look for a version to compare to based on the current commit.
	// Only commits merged by bors will have CI artifacts.
	let merge_base = output(
	self.git()
	.arg("rev-list")
	.arg(format!("--author={}", self.stage0_metadata.config.git_merge_commit_email))
	.args(&["-n1", "--first-parent", "HEAD"]),
	);
	let commit = merge_base.trim_end();
	if commit.is_empty() {
	println!("ERROR: could not find commit hash for downloading rustc");
	println!("HELP: maybe your repository history is too shallow?");
	println!("HELP: consider disabling `download-rustc`");
	println!("HELP: or fetch enough history to include one upstream commit");
	crate::exit!(1);
	}
	// Warn if there were changes to the compiler or standard library since the ancestor commit.
	let has_changes = !t!(self
	.git()
	.args(&["diff-index", "--quiet", &commit, "--", &compiler, &library])
	.status())
	.success();
	if has_changes {
	if if_unchanged {
	if self.verbose > 0 {
	println!(
	"WARNING: saw changes to compiler/ or library/ since {commit}; \
	ignoring `download-rustc`"
	);
	}
	return None;
	}
	println!(
	"WARNING: `download-rustc` is enabled, but there are changes to \
	compiler/ or library/"
	);
	}
	Some(commit.to_string())
	}

3- Replace the placeholder with the commit hash obtained in the previous step.

[carlosguealv]

Sounds good! Will commit as soon as I get it to work!