[ty] Add --config-file CLI arg

crates/ruff_benchmark/benches/ty.rs

@@ -78,7 +78,7 @@ fn setup_tomllib_case() -> Case {
 
     let src_root = SystemPath::new("/src");
     let mut metadata = ProjectMetadata::discover(src_root, &system).unwrap();
-    metadata.apply_cli_options(Options {
+    metadata.apply_options(Options {
         environment: Some(EnvironmentOptions {
             python_version: Some(RangedValue::cli(PythonVersion::PY312)),
             ..EnvironmentOptions::default()
@@ -224,7 +224,7 @@ fn setup_micro_case(code: &str) -> Case {
 
     let src_root = SystemPath::new("/src");
     let mut metadata = ProjectMetadata::discover(src_root, &system).unwrap();
-    metadata.apply_cli_options(Options {
+    metadata.apply_options(Options {
         environment: Some(EnvironmentOptions {
             python_version: Some(RangedValue::cli(PythonVersion::PY312)),
             ..EnvironmentOptions::default()

crates/ty/Cargo.toml

@@ -22,7 +22,7 @@ ty_server = { workspace = true }
 
 anyhow = { workspace = true }
 argfile = { workspace = true }
-clap = { workspace = true, features = ["wrap_help", "string"] }
+clap = { workspace = true, features = ["wrap_help", "string", "env"] }
 clap_complete_command = { workspace = true }
 colored = { workspace = true }
 countme = { workspace = true, features = ["enable"] }

crates/ty/src/args.rs

@@ -107,6 +107,12 @@ pub(crate) struct CheckCommand {
     #[clap(flatten)]
     pub(crate) config: ConfigsArg,
 
+    /// The path to a `ty.toml` file to use for configuration.
+    ///
+    /// While ty configuration can be included in a `pyproject.toml` file, it is not allowed in this context.
+    #[arg(long, env = "TY_CONFIG_FILE", value_name = "PATH")]
+    pub(crate) config_file: Option<SystemPathBuf>,
+
     /// The format to use for printing diagnostic messages.
     #[arg(long)]
     pub(crate) output_format: Option<OutputFormat>,

crates/ty/src/lib.rs

@@ -23,7 +23,7 @@ use ruff_db::diagnostic::{Diagnostic, DisplayDiagnosticConfig, Severity};
 use ruff_db::max_parallelism;
 use ruff_db::system::{OsSystem, SystemPath, SystemPathBuf};
 use salsa::plumbing::ZalsaDatabase;
-use ty_project::metadata::options::Options;
+use ty_project::metadata::options::ProjectOptionsOverrides;
 use ty_project::watch::ProjectWatcher;
 use ty_project::{Db, DummyReporter, Reporter, watch};
 use ty_project::{ProjectDatabase, ProjectMetadata};
@@ -102,13 +102,21 @@ fn run_check(args: CheckCommand) -> anyhow::Result<ExitStatus> {
         .map(|path| SystemPath::absolute(path, &cwd))
         .collect();
 
-    let system = OsSystem::new(cwd);
+    let system = OsSystem::new(&cwd);
     let watch = args.watch;
     let exit_zero = args.exit_zero;
+    let config_file = args
+        .config_file
+        .as_ref()
+        .map(|path| SystemPath::absolute(path, &cwd));
+
+    let mut project_metadata = match &config_file {
+        Some(config_file) => ProjectMetadata::from_config_file(config_file.clone(), &system)?,
+        None => ProjectMetadata::discover(&project_path, &system)?,
+    };
 
-    let cli_options = args.into_options();
-    let mut project_metadata = ProjectMetadata::discover(&project_path, &system)?;
-    project_metadata.apply_cli_options(cli_options.clone());
+    let options = args.into_options();
+    project_metadata.apply_options(options.clone());
     project_metadata.apply_configuration_files(&system)?;
 
     let mut db = ProjectDatabase::new(project_metadata, system)?;
@@ -117,7 +125,8 @@ fn run_check(args: CheckCommand) -> anyhow::Result<ExitStatus> {
         db.project().set_included_paths(&mut db, check_paths);
     }
 
-    let (main_loop, main_loop_cancellation_token) = MainLoop::new(cli_options);
+    let project_options_overrides = ProjectOptionsOverrides::new(config_file, options);
+    let (main_loop, main_loop_cancellation_token) = MainLoop::new(project_options_overrides);
 
     // Listen to Ctrl+C and abort the watch mode.
     let main_loop_cancellation_token = Mutex::new(Some(main_loop_cancellation_token));
@@ -178,19 +187,21 @@ struct MainLoop {
     /// The file system watcher, if running in watch mode.
     watcher: Option<ProjectWatcher>,
 
-    cli_options: Options,
+    project_options_overrides: ProjectOptionsOverrides,
 }
 
 impl MainLoop {
-    fn new(cli_options: Options) -> (Self, MainLoopCancellationToken) {
+    fn new(
+        project_options_overrides: ProjectOptionsOverrides,
+    ) -> (Self, MainLoopCancellationToken) {
         let (sender, receiver) = crossbeam_channel::bounded(10);
 
         (
             Self {
                 sender: sender.clone(),
                 receiver,
                 watcher: None,
-                cli_options,
+                project_options_overrides,
             },
             MainLoopCancellationToken { sender },
         )
@@ -340,7 +351,7 @@ impl MainLoop {
                 MainLoopMessage::ApplyChanges(changes) => {
                     revision += 1;
                     // Automatically cancels any pending queries and waits for them to complete.
-                    db.apply_changes(changes, Some(&self.cli_options));
+                    db.apply_changes(changes, Some(&self.project_options_overrides));
                     if let Some(watcher) = self.watcher.as_mut() {
                         watcher.update(db);
                     }

crates/ty/tests/cli.rs

@@ -1629,6 +1629,63 @@ fn check_conda_prefix_var_to_resolve_path() -> anyhow::Result<()> {
     ----- stderr -----
     WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
     ");
+
+    Ok(())
+}
+
+#[test]
+fn config_file_override() -> anyhow::Result<()> {
+    // Set `error-on-warning` to true in the configuration file
+    // Explicitly set `--warn unresolved-reference` to ensure the rule warns instead of errors
+    let case = TestCase::with_files(vec![
+        ("test.py", r"print(x)  # [unresolved-reference]"),
+        (
+            "ty-override.toml",
+            r#"
+            [terminal]
+            error-on-warning = true
+            "#,
+        ),
+    ])?;
+
+    // Ensure flag works via CLI arg
+    assert_cmd_snapshot!(case.command().arg("--warn").arg("unresolved-reference").arg("--config-file").arg("ty-override.toml"), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    warning[unresolved-reference]: Name `x` used when not defined
+     --> test.py:1:7
+      |
+    1 | print(x)  # [unresolved-reference]
+      |       ^
+      |
+    info: rule `unresolved-reference` was selected on the command line
+
+    Found 1 diagnostic
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    ");
+
+    // Ensure the flag works via an environment variable
+    assert_cmd_snapshot!(case.command().arg("--warn").arg("unresolved-reference").env("TY_CONFIG_FILE", "ty-override.toml"), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    warning[unresolved-reference]: Name `x` used when not defined
+     --> test.py:1:7
+      |
+    1 | print(x)  # [unresolved-reference]
+      |       ^
+      |
+    info: rule `unresolved-reference` was selected on the command line
+
+    Found 1 diagnostic
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    ");
+
     Ok(())
 }