Exit with an error if there are check failures (#12735)

crates/red_knot/src/main.rs

@@ -1,11 +1,13 @@
-use std::num::NonZeroUsize;
+use std::process::ExitCode;
 use std::sync::Mutex;
 
 use clap::Parser;
+use colored::Colorize;
 use crossbeam::channel as crossbeam_channel;
-use red_knot_workspace::site_packages::site_packages_dirs_of_venv;
 
+use red_knot_server::run_server;
 use red_knot_workspace::db::RootDatabase;
+use red_knot_workspace::site_packages::site_packages_dirs_of_venv;
 use red_knot_workspace::watch;
 use red_knot_workspace::watch::WorkspaceWatcher;
 use red_knot_workspace::workspace::WorkspaceMetadata;
@@ -83,13 +85,34 @@ pub enum Command {
     Server,
 }
 
-#[allow(
-    clippy::print_stdout,
-    clippy::unnecessary_wraps,
-    clippy::print_stderr,
-    clippy::dbg_macro
-)]
-pub fn main() -> anyhow::Result<()> {
+#[allow(clippy::print_stdout, clippy::unnecessary_wraps, clippy::print_stderr)]
+pub fn main() -> ExitCode {
+    match run() {
+        Ok(status) => status.into(),
+        Err(error) => {
+            {
+                use std::io::Write;
+
+                // Use `writeln` instead of `eprintln` to avoid panicking when the stderr pipe is broken.
+                let mut stderr = std::io::stderr().lock();
+
+                // This communicates that this isn't a linter error but ruff itself hard-errored for
+                // some reason (e.g. failed to resolve the configuration)
+                writeln!(stderr, "{}", "ruff failed".red().bold()).ok();
+                // Currently we generally only see one error, but e.g. with io errors when resolving
+                // the configuration it is help to chain errors ("resolving configuration failed" ->
+                // "failed to read file: subdir/pyproject.toml")
+                for cause in error.chain() {
+                    writeln!(stderr, "  {} {cause}", "Cause:".bold()).ok();
+                }
+            }
+
+            ExitStatus::Error.into()
+        }
+    }
+}
+
+fn run() -> anyhow::Result<ExitStatus> {
     let Args {
         command,
         current_directory,
@@ -101,20 +124,12 @@ pub fn main() -> anyhow::Result<()> {
         watch,
     } = Args::parse_from(std::env::args().collect::<Vec<_>>());
 
-    let verbosity = verbosity.level();
-    countme::enable(verbosity.is_trace());
-
     if matches!(command, Some(Command::Server)) {
-        let four = NonZeroUsize::new(4).unwrap();
-
-        // by default, we set the number of worker threads to `num_cpus`, with a maximum of 4.
-        let worker_threads = std::thread::available_parallelism()
-            .unwrap_or(four)
-            .max(four);
-
-        return red_knot_server::Server::new(worker_threads)?.run();
+        return run_server().map(|()| ExitStatus::Success);
     }
 
+    let verbosity = verbosity.level();
+    countme::enable(verbosity.is_trace());
     let _guard = setup_tracing(verbosity)?;
 
     let cwd = if let Some(cwd) = current_directory {
@@ -167,17 +182,35 @@ pub fn main() -> anyhow::Result<()> {
         }
     })?;
 
-    if watch {
-        main_loop.watch(&mut db)?;
+    let exit_status = if watch {
+        main_loop.watch(&mut db)?
     } else {
-        main_loop.run(&mut db);
+        main_loop.run(&mut db)
     };
 
-    tracing::trace!("Counts for entire CLI run :\n{}", countme::get_all());
+    tracing::trace!("Counts for entire CLI run:\n{}", countme::get_all());
 
     std::mem::forget(db);
 
-    Ok(())
+    Ok(exit_status)
+}
+
+#[derive(Copy, Clone)]
+pub enum ExitStatus {
+    /// Checking was successful and there were no errors.
+    Success = 0,
+
+    /// Checking was successful but there were errors.
+    Failure = 1,
+
+    /// Checking failed.
+    Error = 2,
+}
+
+impl From<ExitStatus> for ExitCode {
+    fn from(status: ExitStatus) -> Self {
+        ExitCode::from(status as u8)
+    }
 }
 
 struct MainLoop {
@@ -205,7 +238,7 @@ impl MainLoop {
         )
     }
 
-    fn watch(mut self, db: &mut RootDatabase) -> anyhow::Result<()> {
+    fn watch(mut self, db: &mut RootDatabase) -> anyhow::Result<ExitStatus> {
         tracing::debug!("Starting watch mode");
         let sender = self.sender.clone();
         let watcher = watch::directory_watcher(move |event| {
@@ -216,19 +249,21 @@ impl MainLoop {
 
         self.run(db);
 
-        Ok(())
+        Ok(ExitStatus::Success)
     }
 
-    fn run(mut self, db: &mut RootDatabase) {
+    fn run(mut self, db: &mut RootDatabase) -> ExitStatus {
         self.sender.send(MainLoopMessage::CheckWorkspace).unwrap();
 
-        self.main_loop(db);
+        let result = self.main_loop(db);
 
         tracing::debug!("Exiting main loop");
+
+        result
     }
 
     #[allow(clippy::print_stderr)]
-    fn main_loop(&mut self, db: &mut RootDatabase) {
+    fn main_loop(&mut self, db: &mut RootDatabase) -> ExitStatus {
         // Schedule the first check.
         tracing::debug!("Starting main loop");
 
@@ -263,7 +298,11 @@ impl MainLoop {
                     }
 
                     if self.watcher.is_none() {
-                        return;
+                        return if result.is_empty() {
+                            ExitStatus::Success
+                        } else {
+                            ExitStatus::Failure
+                        };
                     }
 
                     tracing::trace!("Counts after last check:\n{}", countme::get_all());
@@ -279,12 +318,14 @@ impl MainLoop {
                     self.sender.send(MainLoopMessage::CheckWorkspace).unwrap();
                 }
                 MainLoopMessage::Exit => {
-                    return;
+                    return ExitStatus::Success;
                 }
             }
 
             tracing::debug!("Waiting for next main loop message.");
         }
+
+        ExitStatus::Success
     }
 }
 

crates/red_knot_server/src/lib.rs

@@ -1,8 +1,11 @@
 #![allow(dead_code)]
 
+use anyhow::Context;
 pub use edit::{DocumentKey, NotebookDocument, PositionEncoding, TextDocument};
-pub use server::Server;
 pub use session::{ClientSettings, DocumentQuery, DocumentSnapshot, Session};
+use std::num::NonZeroUsize;
+
+use crate::server::Server;
 
 #[macro_use]
 mod message;
@@ -23,3 +26,18 @@ pub(crate) type Result<T> = anyhow::Result<T>;
 pub(crate) fn version() -> &'static str {
     env!("CARGO_PKG_VERSION")
 }
+
+pub fn run_server() -> anyhow::Result<()> {
+    let four = NonZeroUsize::new(4).unwrap();
+
+    // by default, we set the number of worker threads to `num_cpus`, with a maximum of 4.
+    let worker_threads = std::thread::available_parallelism()
+        .unwrap_or(four)
+        .max(four);
+
+    Server::new(worker_threads)
+        .context("Failed to start server")?
+        .run()?;
+
+    Ok(())
+}

crates/red_knot_server/src/server.rs

@@ -25,7 +25,7 @@ pub(crate) use connection::ClientSender;
 
 pub(crate) type Result<T> = std::result::Result<T, api::Error>;
 
-pub struct Server {
+pub(crate) struct Server {
     connection: Connection,
     client_capabilities: ClientCapabilities,
     worker_threads: NonZeroUsize,
@@ -33,7 +33,7 @@ pub struct Server {
 }
 
 impl Server {
-    pub fn new(worker_threads: NonZeroUsize) -> crate::Result<Self> {
+    pub(crate) fn new(worker_threads: NonZeroUsize) -> crate::Result<Self> {
         let connection = ConnectionInitializer::stdio();
 
         let (id, init_params) = connection.initialize_start()?;
@@ -113,7 +113,7 @@ impl Server {
         })
     }
 
-    pub fn run(self) -> crate::Result<()> {
+    pub(crate) fn run(self) -> crate::Result<()> {
         type PanicHook = Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send>;
         struct RestorePanicHook {
             hook: Option<PanicHook>,

crates/ruff/src/main.rs

@@ -85,7 +85,6 @@ pub fn main() -> ExitCode {
     match run(args) {
         Ok(code) => code.into(),
         Err(err) => {
-            #[allow(clippy::print_stderr)]
             {
                 use std::io::Write;