revset: drop support for HEAD@git symbol resolution

This was added at f5f61f6 "revset: resolve 'HEAD@git' just like other
pseudo @git branches." As I said in this patch, there was no practical use case
of the HEAD@git symbol.

Suppose we implement colocated workspaces/worktrees #4436, there may be multiple
Git HEAD revisions. This means HEAD can no longer be abstracted as a symbol of
the "git" remote.

CHANGELOG.md

@@ -15,6 +15,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 * Evaluation error of `revsets.short-prefixes` configuration is now reported.
 
+* The `HEAD@git` symbol no longer resolves to the Git HEAD revision. Use
+  `git_head()` or `@-` revset expression instead.
+
 * Help command doesn't work recursively anymore, i.e. `jj workspace help root`
   doesn't work anymore.
 

cli/src/commands/git/import.rs

@@ -33,7 +33,7 @@ pub fn cmd_git_import(
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
     let mut tx = workspace_command.start_transaction();
-    // In non-colocated repo, HEAD@git will never be moved internally by jj.
+    // In non-colocated repo, Git HEAD will never be moved internally by jj.
     // That's why cmd_git_export() doesn't export the HEAD ref.
     git::import_head(tx.repo_mut())?;
     let stats = git::import_refs(tx.repo_mut(), &command.settings().git_settings())?;

cli/tests/test_git_init.rs

@@ -743,7 +743,7 @@ fn test_git_init_colocated_via_flag_git_dir_not_exists() {
     insta::assert_snapshot!(stderr, @r###"
     Initialized repo in "repo"
     "###);
-    // No HEAD@git ref is available yet
+    // No HEAD ref is available yet
     insta::assert_snapshot!(get_log_output(&test_env, &workspace_root), @r###"
     @  230dd059e1b0
     ◆  000000000000

docs/revsets.md

@@ -234,8 +234,7 @@ revsets (expressions) as arguments.
 * `git_refs()`:  All Git ref targets as of the last import. If a Git ref
   is in a conflicted state, all its possible targets are included.
 
-* `git_head()`: The Git `HEAD` target as of the last import. Equivalent to
-  `present(HEAD@git)`.
+* `git_head()`: The Git `HEAD` target as of the last import.
 
 * `visible_heads()`: All visible heads (same as `heads(all())`).
 

lib/src/git.rs

@@ -541,13 +541,13 @@ fn remotely_pinned_commit_ids(view: &View) -> Vec<CommitId> {
         .collect()
 }
 
-/// Imports `HEAD@git` from the underlying Git repo.
+/// Imports HEAD from the underlying Git repo.
 ///
 /// Unlike `import_refs()`, the old HEAD branch is not abandoned because HEAD
 /// move doesn't always mean the old HEAD branch has been rewritten.
 ///
 /// Unlike `reset_head()`, this function doesn't move the working-copy commit to
-/// the child of the new `HEAD@git` revision.
+/// the child of the new HEAD revision.
 pub fn import_head(mut_repo: &mut MutableRepo) -> Result<(), GitImportError> {
     let store = mut_repo.store();
     let git_backend = get_git_backend(store).ok_or(GitImportError::UnexpectedBackend)?;
@@ -938,7 +938,7 @@ fn update_git_ref(
     Ok(())
 }
 
-/// Ensures `HEAD@git` is detached and pointing to the `new_oid`. If `new_oid`
+/// Ensures Git HEAD is detached and pointing to the `new_oid`. If `new_oid`
 /// is `None` (meaning absent), dummy placeholder ref will be set.
 fn update_git_head(
     git_repo: &gix::Repository,
@@ -981,7 +981,7 @@ fn update_git_head(
     Ok(())
 }
 
-/// Sets `HEAD@git` to the parent of the given working-copy commit and resets
+/// Sets Git HEAD to the parent of the given working-copy commit and resets
 /// the Git index.
 pub fn reset_head(
     mut_repo: &mut MutableRepo,
@@ -1012,7 +1012,7 @@ pub fn reset_head(
             false
         };
         let skip_reset = if is_same_tree {
-            // `HEAD@git` already points to a commit with the correct tree contents,
+            // HEAD already points to a commit with the correct tree contents,
             // so we only need to reset the Git index. We can skip the reset if
             // the Git index is empty (i.e. `git add` was never used).
             // In large repositories, this is around 2x faster if the Git index is empty

lib/src/revset.rs

@@ -1582,12 +1582,7 @@ fn reload_repo_at_operation(
 }
 
 fn resolve_remote_bookmark(repo: &dyn Repo, name: &str, remote: &str) -> Option<Vec<CommitId>> {
-    let view = repo.view();
-    let target = match (name, remote) {
-        #[cfg(feature = "git")]
-        ("HEAD", crate::git::REMOTE_NAME_FOR_LOCAL_GIT_REPO) => view.git_head(),
-        (name, remote) => &view.get_remote_bookmark(name, remote).target,
-    };
+    let target = &repo.view().get_remote_bookmark(name, remote).target;
     target
         .is_present()
         .then(|| target.added_ids().cloned().collect())
@@ -1598,23 +1593,21 @@ fn all_bookmark_symbols(
     include_synced_remotes: bool,
 ) -> impl Iterator<Item = String> + '_ {
     let view = repo.view();
-    view.bookmarks()
-        .flat_map(move |(name, bookmark_target)| {
-            // Remote bookmark "x"@"y" may conflict with local "x@y" in unquoted form.
-            let local_target = bookmark_target.local_target;
-            let local_symbol = local_target.is_present().then(|| name.to_owned());
-            let remote_symbols = bookmark_target
-                .remote_refs
-                .into_iter()
-                .filter(move |&(_, remote_ref)| {
-                    include_synced_remotes
-                        || !remote_ref.is_tracking()
-                        || remote_ref.target != *local_target
-                })
-                .map(move |(remote_name, _)| format!("{name}@{remote_name}"));
-            local_symbol.into_iter().chain(remote_symbols)
-        })
-        .chain(view.git_head().is_present().then(|| "HEAD@git".to_owned()))
+    view.bookmarks().flat_map(move |(name, bookmark_target)| {
+        // Remote bookmark "x"@"y" may conflict with local "x@y" in unquoted form.
+        let local_target = bookmark_target.local_target;
+        let local_symbol = local_target.is_present().then(|| name.to_owned());
+        let remote_symbols = bookmark_target
+            .remote_refs
+            .into_iter()
+            .filter(move |&(_, remote_ref)| {
+                include_synced_remotes
+                    || !remote_ref.is_tracking()
+                    || remote_ref.target != *local_target
+            })
+            .map(move |(remote_name, _)| format!("{name}@{remote_name}"));
+        local_symbol.into_iter().chain(remote_symbols)
+    })
 }
 
 fn make_no_such_symbol_error(repo: &dyn Repo, name: impl Into<String>) -> RevsetResolutionError {

lib/src/view.rs

@@ -333,8 +333,8 @@ impl View {
         }
     }
 
-    /// Sets `HEAD@git` to point to the given target. If the target is absent,
-    /// the reference will be cleared.
+    /// Sets Git HEAD to point to the given target. If the target is absent, the
+    /// reference will be cleared.
     pub fn set_git_head_target(&mut self, target: RefTarget) {
         self.data.git_head = target;
     }

lib/tests/test_revset.rs

@@ -806,50 +806,6 @@ fn test_resolve_symbol_tags() {
     );
 }
 
-#[test]
-fn test_resolve_symbol_git_head() {
-    let settings = testutils::user_settings();
-    let test_repo = TestRepo::init();
-    let repo = &test_repo.repo;
-
-    let mut tx = repo.start_transaction(&settings);
-    let mut_repo = tx.repo_mut();
-
-    let commit1 = write_random_commit(mut_repo, &settings);
-
-    // Without HEAD@git
-    insta::assert_debug_snapshot!(
-        resolve_symbol(mut_repo, "HEAD").unwrap_err(), @r###"
-    NoSuchRevision {
-        name: "HEAD",
-        candidates: [],
-    }
-    "###);
-    insta::assert_debug_snapshot!(
-        resolve_symbol(mut_repo, "HEAD@git").unwrap_err(), @r###"
-    NoSuchRevision {
-        name: "HEAD@git",
-        candidates: [],
-    }
-    "###);
-
-    // With HEAD@git
-    mut_repo.set_git_head_target(RefTarget::normal(commit1.id().clone()));
-    insta::assert_debug_snapshot!(
-        resolve_symbol(mut_repo, "HEAD").unwrap_err(), @r###"
-    NoSuchRevision {
-        name: "HEAD",
-        candidates: [
-            "HEAD@git",
-        ],
-    }
-    "###);
-    assert_eq!(
-        resolve_symbol(mut_repo, "HEAD@git").unwrap(),
-        vec![commit1.id().clone()],
-    );
-}
-
 #[test]
 fn test_resolve_symbol_git_refs() {
     let settings = testutils::user_settings();