Remote index branch configuration

crates/cargo-test-support/src/git.rs

@@ -45,9 +45,10 @@ use std::sync::Once;
 use url::Url;
 
 #[must_use]
-pub struct RepoBuilder {
+pub struct RepoBuilder<'br> {
     repo: git2::Repository,
     files: Vec<PathBuf>,
+    branches: Vec<&'br str>,
 }
 
 pub struct Repository(git2::Repository);
@@ -59,33 +60,40 @@ pub fn repo(p: &Path) -> RepoBuilder {
     RepoBuilder::init(p)
 }
 
-impl RepoBuilder {
-    pub fn init(p: &Path) -> RepoBuilder {
+impl<'br> RepoBuilder<'br> {
+    pub fn init(p: &Path) -> Self {
         t!(fs::create_dir_all(p.parent().unwrap()));
         let repo = init(p);
         RepoBuilder {
             repo,
             files: Vec::new(),
+            branches: Vec::new(),
         }
     }
 
     /// Add a file to the repository.
-    pub fn file(self, path: &str, contents: &str) -> RepoBuilder {
+    pub fn file(self, path: &str, contents: &str) -> Self {
         let mut me = self.nocommit_file(path, contents);
         me.files.push(PathBuf::from(path));
         me
     }
 
     /// Add a file that will be left in the working directory, but not added
     /// to the repository.
-    pub fn nocommit_file(self, path: &str, contents: &str) -> RepoBuilder {
+    pub fn nocommit_file(self, path: &str, contents: &str) -> Self {
         let dst = self.repo.workdir().unwrap().join(path);
         t!(fs::create_dir_all(dst.parent().unwrap()));
         t!(fs::write(&dst, contents));
         self
     }
 
-    /// Create the repository and commit the new files.
+    /// Add a branch to the repository pointing at the first commit.
+    pub fn branch(mut self, name: &'br str) -> Self {
+        self.branches.push(name);
+        self
+    }
+
+    /// Create the repository, commit the new files and create the new branches.
     pub fn build(self) -> Repository {
         {
             let mut index = t!(self.repo.index());
@@ -96,10 +104,17 @@ impl RepoBuilder {
             let id = t!(index.write_tree());
             let tree = t!(self.repo.find_tree(id));
             let sig = t!(self.repo.signature());
-            t!(self
-                .repo
-                .commit(Some("HEAD"), &sig, &sig, "Initial commit", &tree, &[]));
+            let head_id =
+                t!(self
+                    .repo
+                    .commit(Some("HEAD"), &sig, &sig, "Initial commit", &tree, &[]));
+            let head_commit = t!(self.repo.find_commit(head_id));
+
+            for branch in self.branches.iter().copied() {
+                t!(self.repo.branch(branch, &head_commit, false));
+            }
         }
+
         let RepoBuilder { repo, .. } = self;
         Repository(repo)
     }

crates/cargo-test-support/src/registry.rs

@@ -46,6 +46,8 @@ pub fn alt_registry_path() -> PathBuf {
 pub fn alt_registry_url() -> Url {
     generate_url("alternative-registry")
 }
+/// The name of the alternative registry's alternative index branch.
+pub const ALT_REG_IDX_ALT_BR: &str = "alternative-branch";
 /// Gets the alternative-registry version of `dl_path`.
 pub fn alt_dl_path() -> PathBuf {
     generate_path("alt_dl")
@@ -78,6 +80,9 @@ pub struct RegistryBuilder {
     replace_crates_io: bool,
     /// If `true`, configures a registry named "alternative".
     alternative: bool,
+    /// If `true` and [`alternative`] is also, configures a registry named
+    /// "alternative" with the "alternative-branch" index branch.
+    alternative_branch: bool,
     /// If set, sets the API url for the "alternative" registry.
     /// This defaults to a directory on the filesystem.
     alt_api_url: Option<String>,
@@ -90,6 +95,7 @@ impl RegistryBuilder {
         RegistryBuilder {
             replace_crates_io: true,
             alternative: false,
+            alternative_branch: false,
             alt_api_url: None,
             add_tokens: true,
         }
@@ -109,6 +115,14 @@ impl RegistryBuilder {
         self
     }
 
+    /// Sets whether or not to initialize the "alternative" registry's index
+    /// onto the "alternative-branch" branch if said registry is set.
+    /// Default is `false`.
+    pub fn alternative_branch(&mut self, alt_br: bool) -> &mut Self {
+        self.alternative_branch = alt_br;
+        self
+    }
+
     /// Sets the API url for the "alternative" registry.
     /// Defaults to a path on the filesystem ([`alt_api_path`]).
     pub fn alternative_api_url(&mut self, url: &str) -> &mut Self {
@@ -152,14 +166,18 @@ impl RegistryBuilder {
         }
         if self.alternative {
             write!(
-                config,
+                &mut config,
                 "
                     [registries.alternative]
                     index = '{}'
                 ",
                 alt_registry_url()
             )
             .unwrap();
+
+            if self.alternative_branch {
+                write!(&mut config, "branch = '{}'\n", ALT_REG_IDX_ALT_BR).unwrap()
+            }
         }
         t!(fs::write(&config_path, config));
 
@@ -178,7 +196,13 @@ impl RegistryBuilder {
         }
 
         if self.replace_crates_io {
-            init_registry(registry_path(), dl_url().into(), api_url(), api_path());
+            init_registry(
+                registry_path(),
+                dl_url().into(),
+                api_url(),
+                api_path(),
+                false,
+            );
         }
 
         if self.alternative {
@@ -189,6 +213,7 @@ impl RegistryBuilder {
                     .as_ref()
                     .map_or_else(alt_api_url, |url| Url::parse(url).expect("valid url")),
                 alt_api_path(),
+                self.alternative_branch,
             );
         }
     }
@@ -316,6 +341,7 @@ pub struct Package {
     features: FeatureMap,
     local: bool,
     alternative: bool,
+    alternative_branch: bool,
     invalid_json: bool,
     proc_macro: bool,
     links: Option<String>,
@@ -367,15 +393,36 @@ pub fn alt_init() {
     RegistryBuilder::new().alternative(true).build();
 }
 
-/// Creates a new on-disk registry.
-pub fn init_registry(registry_path: PathBuf, dl_url: String, api_url: Url, api_path: PathBuf) {
-    // Initialize a new registry.
-    repo(&registry_path)
-        .file(
-            "config.json",
-            &format!(r#"{{"dl":"{}","api":"{}"}}"#, dl_url, api_url),
-        )
+/// Variant of `alt_init` that also initializes the alternative registry index'
+/// alternative branch.
+pub fn alt_br_init() {
+    RegistryBuilder::new()
+        .alternative(true)
+        .alternative_branch(true)
         .build();
+}
+
+/// Creates a new on-disk registry. If `alt_br` is `true`, then an alternative
+/// index branch is created pointing at the first commit.
+pub fn init_registry(
+    registry_path: PathBuf,
+    dl_url: String,
+    api_url: Url,
+    api_path: PathBuf,
+    alt_br: bool,
+) {
+    // Initialize a new registry.
+    let rb = repo(&registry_path).file(
+        "config.json",
+        &format!(r#"{{"dl":"{}","api":"{}"}}"#, dl_url, api_url),
+    );
+
+    if alt_br {
+        rb.branch(ALT_REG_IDX_ALT_BR)
+    } else {
+        rb
+    }
+    .build();
     fs::create_dir_all(api_path.join("api/v1/crates")).unwrap();
 }
 
@@ -393,6 +440,7 @@ impl Package {
             features: BTreeMap::new(),
             local: false,
             alternative: false,
+            alternative_branch: false,
             invalid_json: false,
             proc_macro: false,
             links: None,
@@ -424,6 +472,20 @@ impl Package {
         self
     }
 
+    /// Call with `true` to register a publication in an "alternative registry"
+    /// index' alternative branch.
+    ///
+    /// [`alternative()`] must be set to use this non-default branch.
+    /// The name of the alternative branch is called "alternative-branch".
+    ///
+    /// See `src/doc/src/reference/registries.md` for more details on
+    /// alternative registries. See `alt_registry.rs` for the tests that use
+    /// this.
+    pub fn alternative_branch(&mut self, alt_br: bool) -> &mut Package {
+        self.alternative_branch = alt_br;
+        self
+    }
+
     /// Adds a file to the package.
     pub fn file(&mut self, name: &str, contents: &str) -> &mut Package {
         self.file_with_mode(name, DEFAULT_MODE, contents)
@@ -647,7 +709,29 @@ impl Package {
 
         // Add the new file to the index.
         if !self.local {
+            // Record the publication on the alternative branch if configured.
+            let branch_refname: &str = &format!(
+                "refs/heads/{}",
+                if self.alternative && self.alternative_branch {
+                    ALT_REG_IDX_ALT_BR
+                } else {
+                    "master"
+                }
+            );
             let repo = t!(git2::Repository::open(&registry_path));
+
+            // Switch branch only if not on the correct one to save a bit of time.
+            if t!(repo.head()).name().unwrap() != branch_refname {
+                t!(repo.set_head(branch_refname));
+                // Reset from HEAD in order to properly switch to the desired branch.
+                t!(repo.reset(
+                    &t!(t!(repo.head()).peel(git2::ObjectType::Any)),
+                    git2::ResetType::Mixed,
+                    None
+                ));
+            }
+
+            // Write to the index and create a tree.
             let mut index = t!(repo.index());
             t!(index.add_path(Path::new(&file)));
             t!(index.write());
@@ -656,7 +740,7 @@ impl Package {
             // Commit this change.
             let tree = t!(repo.find_tree(id));
             let sig = t!(repo.signature());
-            let parent = t!(repo.refname_to_id("refs/heads/master"));
+            let parent = t!(repo.refname_to_id(branch_refname));
             let parent = t!(repo.find_commit(parent));
             t!(repo.commit(
                 Some("HEAD"),
@@ -666,6 +750,18 @@ impl Package {
                 &tree,
                 &[&parent]
             ));
+
+            // Put the HEAD back in order to reposition the default branch: the
+            // current repository acts as a remote for client indices which
+            // use `refs/remotes/origin/HEAD` to determine the default branch.
+            if branch_refname != "refs/heads/master" {
+                t!(repo.set_head("refs/heads/master"));
+                t!(repo.reset(
+                    &t!(t!(repo.head()).peel(git2::ObjectType::Any)),
+                    git2::ResetType::Hard,
+                    None
+                ));
+            }
         }
 
         cksum

src/cargo/core/features.rs

@@ -628,7 +628,7 @@ unstable_cli_options!(
     print_im_a_teapot: bool= (HIDDEN),
 
     // All other unstable features.
-    // Please keep this list lexiographically ordered.
+    // Please keep this list lexicographically ordered.
     advanced_env: bool = (HIDDEN),
     avoid_dev_deps: bool = ("Avoid installing dev-dependencies if possible"),
     binary_dep_depinfo: bool = ("Track changes to dependency artifacts"),
@@ -647,6 +647,7 @@ unstable_cli_options!(
     multitarget: bool = ("Allow passing multiple `--target` flags to the cargo subcommand selected"),
     no_index_update: bool = ("Do not update the registry index even if the cache is outdated"),
     panic_abort_tests: bool = ("Enable support to run tests with -Cpanic=abort"),
+    registry_branches: bool = ("Enable the `branch` key for alternative registries in `.cargo/config.toml` files"),
     host_config: bool = ("Enable the [host] section in the .cargo/config.toml file"),
     target_applies_to_host: bool = ("Enable the `target-applies-to-host` key in the .cargo/config.toml file"),
     rustdoc_map: bool = ("Allow passing external documentation mappings to rustdoc"),
@@ -884,6 +885,7 @@ impl CliUnstable {
                 }
             }
             "skip-rustdoc-fingerprint" => self.skip_rustdoc_fingerprint = parse_empty(k, v)?,
+            "registry-branches" => self.registry_branches = parse_empty(k, v)?,
             "compile-progress" => stabilized_warn(k, "1.30", STABILIZED_COMPILE_PROGRESS),
             "offline" => stabilized_err(k, "1.36", STABILIZED_OFFLINE)?,
             "cache-messages" => stabilized_warn(k, "1.40", STABILIZED_CACHE_MESSAGES),