revsets: add trunk alias with default to main/master/root

CHANGELOG.md

@@ -9,6 +9,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Breaking changes
 
+* A default revset-alias function `trunk()` now exists. If you previously defined
+  your own `trunk()` alias it will continue to overwrite the built-in one.
+  Check [revsets.toml](cli/src/config/revsets.toml) and [revsets.md](docs/revset.md)
+  to understand how the function can be adapted.
+
 ### New features
 
 * The `ancestors()` revset function now takes an optional `depth` argument 

cli/src/config.rs

@@ -347,6 +347,7 @@ pub fn default_config() -> config::Config {
         .add_source(from_toml!("config/colors.toml"))
         .add_source(from_toml!("config/merge_tools.toml"))
         .add_source(from_toml!("config/misc.toml"))
+        .add_source(from_toml!("config/revsets.toml"))
         .add_source(from_toml!("config/templates.toml"));
     if cfg!(unix) {
         builder = builder.add_source(from_toml!("config/unix.toml"))

cli/src/config/misc.toml

@@ -1,9 +1,6 @@
 [aliases]
 # Placeholder: added by user
 
-[revset-aliases]
-# Placeholder: added by user
-
 [ui]
 paginate = "auto"
 pager = { command = ["less", "-FRX"], env = { LESSCHARSET = "utf-8" } }

cli/src/config/revsets.toml

@@ -0,0 +1,12 @@
+# NOTE: ensure you update docs/revsets.md with documentation when
+# adding/updating any of these aliases
+
+[revset-aliases]
+'trunk()' = '''
+latest(
+  remote_branches(exact:"main", exact:"origin") | 
+  remote_branches(exact:"master", exact:"origin") | 
+  remote_branches(exact:"trunk", exact:"origin") |
+  root()
+)
+'''

cli/tests/test_builtin_aliases.rs

@@ -0,0 +1,139 @@
+// Copyright 2023 The Jujutsu Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::path::PathBuf;
+
+use common::TestEnvironment;
+
+pub mod common;
+
+fn set_up(trunk_name: &str) -> (TestEnvironment, PathBuf) {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "--git", "origin"]);
+    let origin_path = test_env.env_root().join("origin");
+    let origin_git_repo_path = origin_path
+        .join(".jj")
+        .join("repo")
+        .join("store")
+        .join("git");
+
+    test_env.jj_cmd_success(&origin_path, &["describe", "-m=description 1"]);
+    test_env.jj_cmd_success(&origin_path, &["branch", "create", trunk_name]);
+    test_env.jj_cmd_success(&origin_path, &["new", "root()", "-m=description 2"]);
+    test_env.jj_cmd_success(&origin_path, &["branch", "create", "unrelated_branch"]);
+    test_env.jj_cmd_success(&origin_path, &["git", "export"]);
+
+    test_env.jj_cmd_success(
+        test_env.env_root(),
+        &[
+            "git",
+            "clone",
+            origin_git_repo_path.to_str().unwrap(),
+            "local",
+        ],
+    );
+    let workspace_root = test_env.env_root().join("local");
+    (test_env, workspace_root)
+}
+
+#[test]
+fn test_builtin_alias_trunk_matches_main() {
+    let (test_env, workspace_root) = set_up("main");
+
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["log", "-r", "trunk()"]);
+    insta::assert_snapshot!(stdout, @r###"
+    ◉  lzmmnrxq test.user@example.com 2001-02-03 04:05:08.000 +07:00 main 45a3aa29
+    │  (empty) description 1
+    ~
+    "###);
+}
+
+#[test]
+fn test_builtin_alias_trunk_matches_master() {
+    let (test_env, workspace_root) = set_up("master");
+
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["log", "-r", "trunk()"]);
+    insta::assert_snapshot!(stdout, @r###"
+    ◉  lzmmnrxq test.user@example.com 2001-02-03 04:05:08.000 +07:00 master 45a3aa29
+    │  (empty) description 1
+    ~
+    "###);
+}
+
+#[test]
+fn test_builtin_alias_trunk_matches_trunk() {
+    let (test_env, workspace_root) = set_up("trunk");
+
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["log", "-r", "trunk()"]);
+    insta::assert_snapshot!(stdout, @r###"
+    ◉  lzmmnrxq test.user@example.com 2001-02-03 04:05:08.000 +07:00 trunk 45a3aa29
+    │  (empty) description 1
+    ~
+    "###);
+}
+
+#[test]
+fn test_builtin_alias_trunk_matches_exactly_one_commit() {
+    let (test_env, workspace_root) = set_up("main");
+    let origin_path = test_env.env_root().join("origin");
+    test_env.jj_cmd_success(&origin_path, &["new", "root()", "-m=description 3"]);
+    test_env.jj_cmd_success(&origin_path, &["branch", "create", "master"]);
+
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["log", "-r", "trunk()"]);
+    insta::assert_snapshot!(stdout, @r###"
+    ◉  lzmmnrxq test.user@example.com 2001-02-03 04:05:08.000 +07:00 main 45a3aa29
+    │  (empty) description 1
+    ~
+    "###);
+}
+
+#[test]
+fn test_builtin_alias_trunk_override_alias() {
+    let (test_env, workspace_root) = set_up("override-trunk");
+
+    test_env.add_config(
+        r#"revset-aliases.'trunk()' = 'latest(remote_branches(exact:"override-trunk", exact:"origin"))'"#,
+    );
+
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["log", "-r", "trunk()"]);
+    insta::assert_snapshot!(stdout, @r###"
+    ◉  lzmmnrxq test.user@example.com 2001-02-03 04:05:08.000 +07:00 override-trunk 45a3aa29
+    │  (empty) description 1
+    ~
+    "###);
+}
+
+#[test]
+fn test_builtin_alias_trunk_no_match() {
+    let (test_env, workspace_root) = set_up("no-match-trunk");
+
+    let (stdout, stderr) = test_env.jj_cmd_ok(&workspace_root, &["log", "-r", "trunk()"]);
+    insta::assert_snapshot!(stdout, @r###"
+    ◉  zzzzzzzz root() 00000000
+    "###);
+    insta::assert_snapshot!(stderr, @r###"
+    "###);
+}
+
+#[test]
+fn test_builtin_alias_trunk_no_match_only_exact() {
+    let (test_env, workspace_root) = set_up("maint");
+
+    let (stdout, stderr) = test_env.jj_cmd_ok(&workspace_root, &["log", "-r", "trunk()"]);
+    insta::assert_snapshot!(stdout, @r###"
+    ◉  zzzzzzzz root() 00000000
+    "###);
+    insta::assert_snapshot!(stderr, @r###"
+    "###);
+}

docs/revsets.md

@@ -159,6 +159,25 @@ For example:
 'user(x)' = 'author(x) | committer(x)'
 ```
 
+### Built-in Aliases
+
+The following aliases are built-in and used for certain operations. These functions
+are defined as aliases in order to allow you to overwrite them as needed. 
+See [revsets.toml](https://github.com/martinvonz/jj/blob/main/cli/src/config/revsets.toml)
+for a comprehensive list.
+
+* `trunk()`: Resolves to the head commit for the trunk branch of the `origin`
+  remote. The branches `main`, `master`, and `trunk` are tried in order.
+  If none of the branches exist, it evaluates to `root()`.
+
+  You can [override](./config.md) this as appropriate. If you do, make sure it
+  always resolves to exactly one commit. For example:
+
+  ```toml
+  [revset-aliases]
+  'trunk()' = 'latest(remote_branches(exact:"your-branch", exact:"your-remote"))'
+  ```
+
 ## Examples
 
 Show the parent(s) of the working-copy commit (like `git log -1 HEAD`):