Read user configuration from ~/.config/ruff/ruff.toml on macOS

Cargo.toml

@@ -34,6 +34,7 @@ crossbeam = { version = "0.8.4" }
 dirs = { version = "5.0.0" }
 drop_bomb = { version = "0.1.5" }
 env_logger = { version = "0.11.0" }
+etcetera = { version = "0.8.0" }
 fern = { version = "0.6.1" }
 filetime = { version = "0.2.23" }
 fs-err = { version = "2.11.0" }

crates/ruff_workspace/Cargo.toml

@@ -24,6 +24,7 @@ ruff_macros = { path = "../ruff_macros" }
 anyhow = { workspace = true }
 colored = { workspace = true }
 dirs = { workspace = true }
+etcetera = { workspace = true }
 ignore = { workspace = true }
 is-macro = { workspace = true }
 itertools = { workspace = true }

crates/ruff_workspace/src/pyproject.rs

@@ -3,11 +3,13 @@
 use std::path::{Path, PathBuf};
 
 use anyhow::{Context, Result};
+use etcetera::{AppStrategy, BaseStrategy};
 use log::debug;
 use pep440_rs::VersionSpecifiers;
 use serde::{Deserialize, Serialize};
 
 use ruff_linter::settings::types::PythonVersion;
+use ruff_linter::warn_user_once;
 
 use crate::options::Options;
 
@@ -99,28 +101,31 @@ pub fn find_settings_toml<P: AsRef<Path>>(path: P) -> Result<Option<PathBuf>> {
 /// Find the path to the user-specific `pyproject.toml` or `ruff.toml`, if it
 /// exists.
 pub fn find_user_settings_toml() -> Option<PathBuf> {
-    // Search for a user-specific `.ruff.toml`.
-    let mut path = dirs::config_dir()?;
-    path.push("ruff");
-    path.push(".ruff.toml");
-    if path.is_file() {
-        return Some(path);
-    }
-
-    // Search for a user-specific `ruff.toml`.
-    let mut path = dirs::config_dir()?;
-    path.push("ruff");
-    path.push("ruff.toml");
-    if path.is_file() {
-        return Some(path);
+    let strategy = etcetera::base_strategy::choose_base_strategy().ok()?;
+    let config_dir = strategy.config_dir().join("ruff");
+
+    // Search for a user-specific `.ruff.toml`, then a `ruff.toml`, then a `pyproject.toml`.
+    for filename in [".ruff.toml", "ruff.toml", "pyproject.toml"] {
+        let path = config_dir.join(filename);
+        if path.is_file() {
+            return Some(path);
+        }
     }
 
-    // Search for a user-specific `pyproject.toml`.
-    let mut path = dirs::config_dir()?;
-    path.push("ruff");
-    path.push("pyproject.toml");
-    if path.is_file() {
-        return Some(path);
+    // On macOS, we used to support reading from `/Users/Alice/Library/Application Support`.
+    if cfg!(target_os = "macos") {
+        let deprecated_config_dir = dirs::config_dir()?.join("ruff");
+
+        for file in [".ruff.toml", "ruff.toml", "pyproject.toml"] {
+            let path = deprecated_config_dir.join(file);
+            if path.is_file() {
+                warn_user_once!(
+                    "Reading configuration from `~/Library/Application Support` is deprecated. Please move your configuration to `{}/ruff/{file}`.",
+                    config_dir.display(),
+                );
+                return Some(path);
+            }
+        }
     }
 
     None

docs/faq.md

@@ -606,16 +606,20 @@ Ruff doesn't currently support INI files, like `setup.cfg` or `tox.ini`.
 
 ## How can I change Ruff's default configuration?
 
-When no configuration file is found, Ruff will look for a user-specific `pyproject.toml` or
-`ruff.toml` file as a last resort. This behavior is similar to Flake8's `~/.config/flake8`.
+When no configuration file is found, Ruff will look for a user-specific `ruff.toml` file as a
+last resort. This behavior is similar to Flake8's `~/.config/flake8`.
 
-On macOS, Ruff expects that file to be located at `/Users/Alice/Library/Application Support/ruff/ruff.toml`.
+On macOS and Linux, Ruff expects that file to be located at `~/.config/ruff/ruff.toml`,
+and respects the `XDG_CONFIG_HOME` specification.
 
-On Linux, Ruff expects that file to be located at `/home/alice/.config/ruff/ruff.toml`.
+On Windows, Ruff expects that file to be located at `~\AppData\Roaming\ruff\ruff.toml`.
 
-On Windows, Ruff expects that file to be located at `C:\Users\Alice\AppData\Roaming\ruff\ruff.toml`.
+!!! note
+  Prior to `v0.5.0`, Ruff would read user-specific configuration from
+  `/Users/Alice/Library/Application Support/ruff/ruff.toml` on macOS. While Ruff will still respect
+  such configuration files, the use of `~/Library/ Application Support` is considered deprecated.
 
-For more, see the [`dirs`](https://docs.rs/dirs/4.0.0/dirs/fn.config_dir.html) crate.
+For more, see the [`etcetera`](https://crates.io/crates/etcetera) crate.
 
 ## Ruff tried to fix something — but it broke my code. What's going on?