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

Add a new `--show-sources` 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.
This is a good fit for repository config files, as the working
directory is likely to be have a short path to `.jj/repo`.

However, the user's home directory may be some distance from the current
working directory, making it difficult to recognize where the config
file is located. For example:

  ../../../../.config/jj/config.toml

vs

  /home/user/.config/jj/config.toml

We therefore attempt to canonicalize the path for user config files.
Should this fail, we use the path as-is.

CHANGELOG.md

@@ -23,6 +23,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `jj git fetch` now accepts `-b` as a shorthand for `--branch`, making it more
   consistent with other commands that accept a branch
 
+* `jj config list` gained a `--show-sources` flag to display the origin 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_sources: 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_sources {
+            format_origin(value.origin(), source)
+        } else {
+            String::from("")
+        };
+
         writeln!(
             ui.stdout(),
-            "{}{}={}",
+            "{origin}{}{}={}",
             if *is_overridden { "# " } else { "" },
             path.join("."),
             serialize_config_value(value)
@@ -304,3 +317,23 @@ pub(crate) fn cmd_config_path(
     )?;
     Ok(())
 }
+
+fn format_origin(origin: Option<&str>, source: &ConfigSource) -> String {
+    let Some(origin) = origin else {
+        return format!("{source}:\t");
+    };
+
+    // `config::FileSourceFile::resolve()` returns a relative path. For user
+    // configs, try to convert them to absolute paths for easier recognition,
+    // falling back to the original value on failure. Retain relative paths for
+    // repo configs as these are likely to be within the current directory.
+    let origin = if matches!(source, ConfigSource::User) {
+        Path::new(origin)
+            .canonicalize()
+            .map(|p| p.to_string_lossy().to_string())
+            .unwrap_or_else(|_| origin.to_string())
+    } else {
+        origin.to_string()
+    };
+    format!("{source}:{origin}\t")
+}

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 fmt::Display for ConfigSource {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            ConfigSource::Default => write!(f, "default"),
+            ConfigSource::Env => write!(f, "env"),
+            ConfigSource::User => write!(f, "usercfg"),
+            ConfigSource::Repo => write!(f, "repocfg"),
+            ConfigSource::CommandArg => write!(f, "command line"),
+        }
+    }
+}
+
 #[derive(Clone, Debug, PartialEq)]
 pub struct AnnotatedValue {
     pub path: Vec<String>,

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

@@ -480,6 +480,10 @@ List variables set in config file, along with their values
 
   Possible values: `true`, `false`
 
+* `--show-sources` — 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_sources() {
+    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-sources",
+        ],
+    );
+
+    // 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:.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"
+    command line:	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-sources"],
+    );
+    assert!(stdout.contains(r#"default:	colors.diff header="yellow""#));
+}
+
 #[test]
 fn test_config_list_layer() {
     let mut test_env = TestEnvironment::default();