From 5874d5abfb5385dd070a057007866b79fcc44cee Mon Sep 17 00:00:00 2001
From: Martin von Zweigbergk <martinvonz@google.com>
Date: Wed, 13 Oct 2021 09:07:18 -0700
Subject: [PATCH] revset: add none() function

---
 lib/src/revset.rs        | 10 ++++++++++
 lib/tests/test_revset.rs | 10 ++++++++++
 2 files changed, 20 insertions(+)

diff --git a/lib/src/revset.rs b/lib/src/revset.rs
index 73618523e..54113b49d 100644
--- a/lib/src/revset.rs
+++ b/lib/src/revset.rs
@@ -552,6 +552,16 @@ fn parse_function_expression(
                 })
             }
         }
+        "none" => {
+            if arg_count == 0 {
+                Ok(RevsetExpression::none())
+            } else {
+                Err(RevsetParseError::InvalidFunctionArguments {
+                    name,
+                    message: "Expected 0 arguments".to_string(),
+                })
+            }
+        }
         "heads" => {
             if arg_count == 0 {
                 Ok(RevsetExpression::heads())
diff --git a/lib/tests/test_revset.rs b/lib/tests/test_revset.rs
index 7f63d1dca..1aa063eb2 100644
--- a/lib/tests/test_revset.rs
+++ b/lib/tests/test_revset.rs
@@ -765,6 +765,16 @@ fn test_evaluate_expression_descendants(use_git: bool) {
     tx.discard();
 }
 
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
+fn test_evaluate_expression_none(use_git: bool) {
+    let settings = testutils::user_settings();
+    let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
+
+    // none() is empty (doesn't include the checkout, for example)
+    assert_eq!(resolve_commit_ids(repo.as_repo_ref(), "none()"), vec![]);
+}
+
 #[test_case(false ; "local backend")]
 #[test_case(true ; "git backend")]
 fn test_evaluate_expression_heads(use_git: bool) {