build-manifest: accept the Rust version instead of the monorepo path

This commit changes the way build-manifest is invoked, to let it accept
the Rust version directly instead of requiring the path of the Rust
monorepo and letting build-manifest figure out the path on its own.

This allows to run build-manifest without a clone of the monorepo.

src/bootstrap/dist.rs

@@ -2353,7 +2353,7 @@ impl Step for HashSign {
         cmd.arg(today.trim());
         cmd.arg(addr);
         cmd.arg(&builder.config.channel);
-        cmd.arg(&builder.src);
+        cmd.arg(&builder.version);
         cmd.env("BUILD_MANIFEST_LEGACY", "1");
 
         builder.create_dir(&distdir(builder));

src/bootstrap/run.rs

@@ -77,7 +77,7 @@ impl Step for BuildManifest {
         cmd.arg(today.trim());
         cmd.arg(addr);
         cmd.arg(&builder.config.channel);
-        cmd.arg(&builder.src);
+        cmd.arg(&builder.version);
 
         builder.create_dir(&distdir(builder));
         builder.run(&mut cmd);

src/tools/build-manifest/README.md

@@ -21,8 +21,8 @@ Then, you can generate the manifest and all the packages from `path/to/dist` to
 
 ```
 $ cargo +nightly run path/to/dist path/to/output 1970-01-01 http://example.com \
-    CHANNEL path/to/rust/repo
+    CHANNEL VERSION
 ```
 
 Remember to replace `CHANNEL` with the channel you produced dist artifacts of
-and `path/to/rust/repo` with the path to your checkout of the Rust repository.
+and `VERSION` with the current Rust version.

src/tools/build-manifest/src/main.rs

@@ -221,7 +221,7 @@ fn main() {
     let date = args.next().unwrap();
     let s3_address = args.next().unwrap();
     let channel = args.next().unwrap();
-    let monorepo_path = args.next().unwrap();
+    let rustc_version = args.next().unwrap();
 
     // Do not ask for a passphrase while manually testing
     let mut passphrase = String::new();
@@ -231,7 +231,7 @@ fn main() {
     }
 
     Builder {
-        versions: Versions::new(&channel, &input, Path::new(&monorepo_path)).unwrap(),
+        versions: Versions::new(&channel, &rustc_version, &input).unwrap(),
 
         input,
         output,

src/tools/build-manifest/src/versions.rs

@@ -1,4 +1,4 @@
-use anyhow::{Context, Error};
+use anyhow::Error;
 use flate2::read::GzDecoder;
 use std::collections::HashMap;
 use std::fs::File;
@@ -93,17 +93,10 @@ pub(crate) struct Versions {
 }
 
 impl Versions {
-    pub(crate) fn new(
-        channel: &str,
-        dist_path: &Path,
-        monorepo_root: &Path,
-    ) -> Result<Self, Error> {
+    pub(crate) fn new(channel: &str, rustc_version: &str, dist_path: &Path) -> Result<Self, Error> {
         Ok(Self {
             channel: channel.into(),
-            rustc_version: std::fs::read_to_string(monorepo_root.join("src").join("version"))
-                .context("failed to read the rustc version from src/version")?
-                .trim()
-                .to_string(),
+            rustc_version: rustc_version.into(),
             dist_path: dist_path.into(),
             versions: HashMap::new(),
         })