Allow configuring upstream repository for pull

src/bin/rustc_josh_sync.rs

@@ -3,7 +3,7 @@ use clap::Parser;
 use rustc_josh_sync::SyncContext;
 use rustc_josh_sync::config::{JoshConfig, load_config};
 use rustc_josh_sync::josh::{JoshProxy, try_install_josh};
-use rustc_josh_sync::sync::{GitSync, RustcPullError, UPSTREAM_REPO};
+use rustc_josh_sync::sync::{DEFAULT_UPSTREAM_REPO, GitSync, RustcPullError};
 use rustc_josh_sync::utils::{get_current_head_sha, prompt};
 use std::path::{Path, PathBuf};
 
@@ -23,6 +23,11 @@ enum Command {
     /// Pull changes from the main `rust-lang/rust` repository.
     /// This creates new commits that should be then merged into this subtree repository.
     Pull {
+        /// Override the upstream repository from which we pull changes.
+        /// Can be used to perform experimental pulls e.g. to test changes in the subtree repository
+        /// that have not yet been merged in `rust-lang/rust`.
+        #[clap(long, default_value(DEFAULT_UPSTREAM_REPO))]
+        upstream: String,
         #[clap(long, default_value(DEFAULT_CONFIG_PATH))]
         config_path: PathBuf,
         #[clap(long, default_value(DEFAULT_RUST_VERSION_PATH))]
@@ -69,11 +74,12 @@ fn main() -> anyhow::Result<()> {
         Command::Pull {
             config_path,
             rust_version_path,
+            upstream,
         } => {
             let ctx = load_context(&config_path, &rust_version_path)?;
             let josh = get_josh_proxy()?;
             let sync = GitSync::new(ctx.clone(), josh);
-            match sync.rustc_pull() {
+            match sync.rustc_pull(upstream) {
                 Ok(result) => {
                     if !maybe_create_gh_pr(
                         &ctx.config.full_repo_name(),
@@ -124,7 +130,7 @@ r? @ghost"#,
 
             println!(
                 r#"You can create the rustc PR using the following URL:
-https://github.com/{UPSTREAM_REPO}/compare/{username}:{branch}?quick_pull=1&title={}&body={}"#,
+https://github.com/{DEFAULT_UPSTREAM_REPO}/compare/{username}:{branch}?quick_pull=1&title={}&body={}"#,
                 urlencoding::encode(&title),
                 urlencoding::encode(&merge_msg)
             );

src/sync.rs

@@ -6,7 +6,7 @@ use crate::utils::{run_command, stream_command};
 use anyhow::{Context, Error};
 use std::path::{Path, PathBuf};
 
-pub const UPSTREAM_REPO: &str = "rust-lang/rust";
+pub const DEFAULT_UPSTREAM_REPO: &str = "rust-lang/rust";
 
 pub enum RustcPullError {
     /// No changes are available to be pulled.
@@ -35,13 +35,13 @@ impl GitSync {
         Self { context, proxy }
     }
 
-    pub fn rustc_pull(&self) -> Result<PullResult, RustcPullError> {
+    pub fn rustc_pull(&self, upstream_repo: String) -> Result<PullResult, RustcPullError> {
         // The upstream commit that we want to pull
         let upstream_sha = {
             let out = run_command([
                 "git",
                 "ls-remote",
-                &format!("https://github.com/{UPSTREAM_REPO}"),
+                &format!("https://github.com/{upstream_repo}"),
                 "HEAD",
             ])
             .context("cannot fetch upstream commit")?;
@@ -59,7 +59,7 @@ impl GitSync {
             .start(&self.context.config)
             .context("cannot start josh-proxy")?;
         let josh_url = josh.git_url(
-            UPSTREAM_REPO,
+            &upstream_repo,
             Some(&upstream_sha),
             &self.context.config.construct_josh_filter(),
         );
@@ -98,7 +98,7 @@ impl GitSync {
         })?;
 
         let prep_message = format!(
-            r#"Prepare for merging from {UPSTREAM_REPO}
+            r#"Prepare for merging from {upstream_repo}
 
 This updates the rust-version file to {upstream_sha}."#,
         );
@@ -144,9 +144,9 @@ This updates the rust-version file to {upstream_sha}."#,
         println!("incoming ref: {incoming_ref}");
 
         let merge_message = format!(
-            r#"Merge ref '{upstream_head_short}' from {UPSTREAM_REPO}
+            r#"Merge ref '{upstream_head_short}' from {upstream_repo}
 
-Pull recent changes from https://github.com/{UPSTREAM_REPO} via Josh.
+Pull recent changes from https://github.com/{upstream_repo} via Josh.
 
 Upstream ref: {upstream_sha}
 Filtered ref: {incoming_ref}
@@ -241,7 +241,7 @@ This merge was created using https://github.com/rust-lang/josh-sync.
             &[
                 "git",
                 "fetch",
-                &format!("https://github.com/{UPSTREAM_REPO}"),
+                &format!("https://github.com/{DEFAULT_UPSTREAM_REPO}"),
                 &base_upstream_sha,
             ],
             &rustc_git,