cli: allow config in ~/.jjconfig.toml

As I said in 095fb9fef4, removing support for `~/.jjconfig` was an
experiment. I've heard from a few people (including in #233) that they
would prefer to have configs in the home directory. This patch
therefore restores that functionality, except I added a `.toml`
extension to the file to clarify the expected format to users and
editors.

After this patch, we still allow configs in `$XDG_CONFIG_HOME` (and
the other paths used by `dirs::config_dir()`), but we error out there
are config files in both that location and `~/.jjconfig.toml`.

CHANGELOG.md

@@ -40,6 +40,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   "sparse", only to different degrees. Use the `jj sparse` command to manage
   the paths included in the sparse checkout.
 
+* Configuration is now also read from `~/.jjconfig.toml`.
+
 * The `$JJ_CONFIG` environment variable can now point to a directory. If it
   does, all files in the directory will be read, in alphabetical order.
 

src/config.rs

@@ -14,25 +14,39 @@
 
 use std::env;
 use std::path::PathBuf;
-use thiserror::Error;
 
 use jujutsu_lib::settings::UserSettings;
+use thiserror::Error;
 
 #[derive(Error, Debug)]
 pub enum ConfigError {
     #[error(transparent)]
     ConfigReadError(#[from] config::ConfigError),
+    #[error("Both {0} and {1} exist. Please consolidate you configs in one of them.")]
+    AmbiguousSource(PathBuf, PathBuf),
 }
 
-fn config_path() -> Option<PathBuf> {
+fn config_path() -> Result<Option<PathBuf>, ConfigError> {
     if let Ok(config_path) = env::var("JJ_CONFIG") {
         // TODO: We should probably support colon-separated (std::env::split_paths)
         // paths here
-        Some(PathBuf::from(config_path))
+        Ok(Some(PathBuf::from(config_path)))
     } else {
         // TODO: Should we drop the final `/config.toml` and read all files in the
         // directory?
-        dirs::config_dir().map(|config_dir| config_dir.join("jj").join("config.toml"))
+        let platform_specific_config_path = dirs::config_dir()
+            .map(|config_dir| config_dir.join("jj").join("config.toml"))
+            .filter(|path| path.exists());
+        let home_config_path = dirs::home_dir()
+            .map(|home_dir| home_dir.join(".jjconfig.toml"))
+            .filter(|path| path.exists());
+        match (&platform_specific_config_path, &home_config_path) {
+            (Some(xdg_config_path), Some(home_config_path)) => Err(ConfigError::AmbiguousSource(
+                xdg_config_path.clone(),
+                home_config_path.clone(),
+            )),
+            _ => Ok(platform_specific_config_path.or(home_config_path)),
+        }
     }
 }
 
@@ -66,7 +80,7 @@ fn env_overrides() -> config::Config {
 pub fn read_config() -> Result<UserSettings, ConfigError> {
     let mut config_builder = config::Config::builder().add_source(env_base());
 
-    if let Some(config_path) = config_path() {
+    if let Some(config_path) = config_path()? {
         let mut files = vec![];
         if config_path.is_dir() {
             if let Ok(read_dir) = config_path.read_dir() {

src/main.rs

@@ -48,8 +48,7 @@ fn main() {
         }
         Err(err) => {
             let mut ui = Ui::for_terminal(UserSettings::default());
-            ui.write_error(&format!("Invalid config: {}\n", err))
-                .unwrap();
+            ui.write_error(&format!("Config error: {}\n", err)).unwrap();
             std::process::exit(1);
         }
     }

tests/test_global_opts.rs

@@ -126,7 +126,7 @@ fn test_invalid_config() {
     test_env.add_config(b"[section]key = value-missing-quotes");
     let stderr = test_env.jj_cmd_failure(test_env.env_root(), &["init", "repo"]);
     insta::assert_snapshot!(stderr.replace('\\', "/"), @r###"
-    Invalid config: expected newline, found an identifier at line 1 column 10 in config/config0001.toml
+    Config error: expected newline, found an identifier at line 1 column 10 in config/config0001.toml
     "###);
 }