cli: Add --show-origin option to config list

Add a new `--show-origin` option to `jj config list` to display the
source type and file path (when present) of config values. In cases
where the user config path is a directory, the individual file
containing a given value will be displayed.

The method that captures config file paths,
`config::FileSourceFile::resolve()`, converts them to relative paths.
These may be difficult to recognize when the current working directory
is distant from a config file's location. We therefore attempt to
canonicalize all file paths. Should this fail, we use the path as-is.

CHANGELOG.md

@@ -46,6 +46,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   [#2971](https://github.com/martinvonz/jj/issues/2971)). This may become the
   default depending on feedback.
 
+* `jj config list` gained a `--show-origin` flag to display the source of
+  config values.
+
 ### Fixed bugs
 
 * On Windows, symlinks in the repo are now materialized as regular files in the

cli/src/commands/config.rs

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 use std::io::Write;
+use std::path::Path;
 
 use clap::builder::NonEmptyStringValueParser;
 use itertools::Itertools;
@@ -84,6 +85,11 @@ pub(crate) struct ConfigListArgs {
     /// Allow printing overridden values.
     #[arg(long)]
     pub include_overridden: bool,
+    /// Display the source of all listed config values with type (default, env,
+    /// usercfg, repocfg, command line) and the source file path for usercfg
+    /// and repocfg.
+    #[arg(long)]
+    pub show_origin: bool,
     /// Target the user-level config
     #[arg(long)]
     user: bool,
@@ -204,9 +210,16 @@ pub(crate) fn cmd_config_list(
         if !args.include_defaults && *source == ConfigSource::Default {
             continue;
         }
+
+        let origin = if args.show_origin {
+            format_origin(value.origin(), source)
+        } else {
+            String::from("")
+        };
+
         writeln!(
             ui.stdout(),
-            "{}{}={}",
+            "{origin}{}{}={}",
             if *is_overridden { "# " } else { "" },
             path.join("."),
             serialize_config_value(value)
@@ -304,3 +317,17 @@ pub(crate) fn cmd_config_path(
     )?;
     Ok(())
 }
+
+fn format_origin(origin: Option<&str>, source: &ConfigSource) -> String {
+    let Some(origin) = origin else {
+        return format!("{}: ", source.description());
+    };
+
+    // `config::FileSourceFile::resolve()` returns a relative path. Try to
+    // convert them to absolute paths for easier recognition, falling back
+    // to the original value on failure.
+    let canon = Path::new(origin).canonicalize();
+    let path = canon.as_deref().unwrap_or_else(|_| Path::new(origin));
+
+    format!("{} {}: ", source.description(), path.display())
+}

cli/src/config.rs

@@ -38,12 +38,23 @@ pub enum ConfigError {
 pub enum ConfigSource {
     Default,
     Env,
-    // TODO: Track explicit file paths, especially for when user config is a dir.
     User,
     Repo,
     CommandArg,
 }
 
+impl ConfigSource {
+    pub fn description(&self) -> &str {
+        match self {
+            ConfigSource::Default => "default",
+            ConfigSource::Env => "env",
+            ConfigSource::User => "usercfg",
+            ConfigSource::Repo => "repocfg",
+            ConfigSource::CommandArg => "cmdline",
+        }
+    }
+}
+
 #[derive(Clone, Debug, PartialEq)]
 pub struct AnnotatedValue {
     pub path: Vec<String>,

cli/tests/cli-reference@.md.snap

@@ -475,6 +475,10 @@ List variables set in config file, along with their values
 
   Possible values: `true`, `false`
 
+* `--show-origin` — Display the source of all listed config values with type (default, env, usercfg, repocfg, command line) and the source file path for usercfg and repocfg
+
+  Possible values: `true`, `false`
+
 * `--user` — Target the user-level config
 
   Possible values: `true`, `false`

cli/tests/test_config_command.rs

@@ -125,6 +125,72 @@ fn test_config_list_all() {
     "###);
 }
 
+#[test]
+fn test_config_list_show_origin() {
+    let mut test_env = TestEnvironment::default();
+    test_env.jj_cmd_ok(test_env.env_root(), &["init", "repo", "--git"]);
+    let repo_path = test_env.env_root().join("repo");
+
+    // Create multiple user configs.
+    test_env.add_config(
+        r#"
+        user-key-1 = "user-val-1"
+        "#,
+    );
+
+    test_env.add_config(
+        r#"
+        user-key-2 = "user-val-2"
+        "#,
+    );
+
+    // Env
+    test_env.add_env_var("env-key", "env-value");
+
+    // Repo
+    test_env.jj_cmd_ok(
+        &repo_path,
+        &["config", "set", "--repo", "repo-key", "repo-val"],
+    );
+
+    let stdout = test_env.jj_cmd_success(
+        &repo_path,
+        &[
+            "config",
+            "list",
+            "--config-toml",
+            "cmd-key='cmd-val'",
+            "--show-origin",
+        ],
+    );
+
+    // Paths starting with `$TEST_ENV` confirm that the relative path returned by
+    // `Value.origin()` has been converted to an absolute path.
+    insta::assert_snapshot!(stdout, @r###"
+    usercfg $TEST_ENV/config/config0001.toml: template-aliases.format_time_range(time_range)="time_range.start() ++ \" - \" ++ time_range.end()"
+    usercfg $TEST_ENV/config/config0002.toml: user-key-1="user-val-1"
+    usercfg $TEST_ENV/config/config0003.toml: user-key-2="user-val-2"
+    repocfg $TEST_ENV/repo/.jj/repo/config.toml: repo-key="repo-val"
+    env: debug.commit-timestamp="2001-02-03T04:05:09+07:00"
+    env: debug.operation-timestamp="2001-02-03T04:05:09+07:00"
+    env: debug.randomness-seed="3"
+    env: operation.hostname="host.example.com"
+    env: operation.username="test-username"
+    env: user.email="[email protected]"
+    env: user.name="Test User"
+    cmdline: cmd-key="cmd-val"
+    "###);
+
+    // Run again with defaults shown. Rather than assert the full output which
+    // will change when any default config value is added or updated, check only
+    // one value to validate the formatting is correct.
+    let stdout = test_env.jj_cmd_success(
+        &repo_path,
+        &["config", "list", "--include-defaults", "--show-origin"],
+    );
+    assert!(stdout.contains(r#"default: colors.diff header="yellow""#));
+}
+
 #[test]
 fn test_config_list_layer() {
     let mut test_env = TestEnvironment::default();