revsets: add revset function for getting all git refs

This adds a `git_refs()` revset that includes all commits pointed to
by a git ref. It's not very useful yet because the graph log doesn't
use the right type of edges for non-contiguous commits.

lib/src/revset.rs

@@ -119,6 +119,7 @@ pub enum RevsetExpression {
     },
     AllHeads,
     PublicHeads,
+    GitRefs,
     NonObsoleteHeads(Rc<RevsetExpression>),
     Description {
         needle: String,
@@ -410,6 +411,16 @@ fn parse_function_expression(
                 })
             }
         }
+        "git_refs" => {
+            if arg_count == 0 {
+                Ok(RevsetExpression::GitRefs)
+            } else {
+                Err(RevsetParseError::InvalidFunctionArguments {
+                    name,
+                    message: "Expected 0 arguments".to_string(),
+                })
+            }
+        }
         "description" => {
             if !(1..=2).contains(&arg_count) {
                 return Err(RevsetParseError::InvalidFunctionArguments {
@@ -726,7 +737,7 @@ pub fn evaluate_expression<'revset, 'repo: 'revset>(
             let mut parent_entries: Vec<_> =
                 base_set.iter().flat_map(|entry| entry.parents()).collect();
             parent_entries.sort_by_key(|b| Reverse(b.position()));
-            parent_entries.dedup_by_key(|entry| entry.position());
+            parent_entries.dedup();
             Ok(Box::new(EagerRevset {
                 index_entries: parent_entries,
             }))
@@ -802,6 +813,18 @@ pub fn evaluate_expression<'revset, 'repo: 'revset>(
             index_entries.sort_by_key(|b| Reverse(b.position()));
             Ok(Box::new(EagerRevset { index_entries }))
         }
+        RevsetExpression::GitRefs => {
+            let index = repo.index();
+            let mut index_entries: Vec<_> = repo
+                .view()
+                .git_refs()
+                .values()
+                .map(|id| index.entry_by_id(id).unwrap())
+                .collect();
+            index_entries.sort_by_key(|b| Reverse(b.position()));
+            index_entries.dedup();
+            Ok(Box::new(EagerRevset { index_entries }))
+        }
         RevsetExpression::Description {
             needle,
             candidates: base_expression,
@@ -870,7 +893,6 @@ fn non_obsolete_heads<'revset, 'repo: 'revset>(
         .map(|id| index.entry_by_id(id).unwrap())
         .collect();
     index_entries.sort_by_key(|b| Reverse(b.position()));
-    index_entries.sort_by_key(|b| Reverse(b.position()));
     Box::new(EagerRevset { index_entries })
 }
 

lib/tests/test_revset.rs

@@ -714,6 +714,41 @@ fn test_evaluate_expression_public_heads(use_git: bool) {
     tx.discard();
 }
 
+#[test_case(false ; "local store")]
+#[test_case(true ; "git store")]
+fn test_evaluate_expression_git_refs(use_git: bool) {
+    let settings = testutils::user_settings();
+    let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
+
+    let mut tx = repo.start_transaction("test");
+    let mut_repo = tx.mut_repo();
+
+    let commit1 = testutils::create_random_commit(&settings, &repo).write_to_repo(mut_repo);
+    let commit2 = testutils::create_random_commit(&settings, &repo).write_to_repo(mut_repo);
+
+    // Can get git refs when there are none
+    assert_eq!(
+        resolve_commit_ids(mut_repo.as_repo_ref(), "git_refs()"),
+        vec![]
+    );
+    // Can get a mix of git refs
+    mut_repo.insert_git_ref("refs/heads/branch1".to_string(), commit1.id().clone());
+    mut_repo.insert_git_ref("refs/tags/tag1".to_string(), commit2.id().clone());
+    assert_eq!(
+        resolve_commit_ids(mut_repo.as_repo_ref(), "git_refs()"),
+        vec![commit2.id().clone(), commit1.id().clone()]
+    );
+    // Two refs pointing to the same commit does not result in a duplicate in the
+    // revset
+    mut_repo.insert_git_ref("refs/tags/tag2".to_string(), commit2.id().clone());
+    assert_eq!(
+        resolve_commit_ids(mut_repo.as_repo_ref(), "git_refs()"),
+        vec![commit2.id().clone(), commit1.id().clone()]
+    );
+
+    tx.discard();
+}
+
 #[test_case(false ; "local store")]
 #[test_case(true ; "git store")]
 fn test_evaluate_expression_obsolete(use_git: bool) {