10 files changed, 248 insertions, 114 deletions

diff --git a/Cargo.lock b/Cargo.lock
index f6df77206..f76857724 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1092,6 +1092,7 @@ dependencies = [
  "cargo_metadata",
  "log",
  "ra_arena",
+ "ra_cargo_watch",
  "ra_cfg",
  "ra_db",
  "rustc-hash",
diff --git a/crates/ra_cargo_watch/src/lib.rs b/crates/ra_cargo_watch/src/lib.rs
index 1a6926db3..71aa28f0a 100644
--- a/crates/ra_cargo_watch/src/lib.rs
+++ b/crates/ra_cargo_watch/src/lib.rs
@@ -9,8 +9,8 @@ use lsp_types::{
 };
 use std::{
     io::{BufRead, BufReader},
-    path::PathBuf,
-    process::{Command, Stdio},
+    path::{Path, PathBuf},
+    process::{Child, Command, Stdio},
     thread::JoinHandle,
     time::Instant,
 };
@@ -246,18 +246,71 @@ enum CheckEvent {
     End,
 }
 
+pub fn run_cargo(
+    args: &[String],
+    current_dir: Option<&Path>,
+    mut on_message: impl FnMut(cargo_metadata::Message) -> bool,
+) -> Child {
+    let mut command = Command::new("cargo");
+    if let Some(current_dir) = current_dir {
+        command.current_dir(current_dir);
+    }
+
+    let mut child = command
+        .args(args)
+        .stdout(Stdio::piped())
+        .stderr(Stdio::null())
+        .stdin(Stdio::null())
+        .spawn()
+        .expect("couldn't launch cargo");
+
+    // We manually read a line at a time, instead of using serde's
+    // stream deserializers, because the deserializer cannot recover
+    // from an error, resulting in it getting stuck, because we try to
+    // be resillient against failures.
+    //
+    // Because cargo only outputs one JSON object per line, we can
+    // simply skip a line if it doesn't parse, which just ignores any
+    // erroneus output.
+    let stdout = BufReader::new(child.stdout.take().unwrap());
+    for line in stdout.lines() {
+        let line = match line {
+            Ok(line) => line,
+            Err(err) => {
+                log::error!("Couldn't read line from cargo: {}", err);
+                continue;
+            }
+        };
+
+        let message = serde_json::from_str::<cargo_metadata::Message>(&line);
+        let message = match message {
+            Ok(message) => message,
+            Err(err) => {
+                log::error!("Invalid json from cargo check, ignoring ({}): {:?} ", err, line);
+                continue;
+            }
+        };
+
+        if !on_message(message) {
+            break;
+        }
+    }
+
+    child
+}
+
 impl WatchThread {
     fn dummy() -> WatchThread {
         WatchThread { handle: None, message_recv: never() }
     }
 
-    fn new(options: &CheckOptions, workspace_root: &PathBuf) -> WatchThread {
+    fn new(options: &CheckOptions, workspace_root: &Path) -> WatchThread {
         let mut args: Vec<String> = vec![
             options.command.clone(),
             "--workspace".to_string(),
             "--message-format=json".to_string(),
             "--manifest-path".to_string(),
-            format!("{}/Cargo.toml", workspace_root.to_string_lossy()),
+            format!("{}/Cargo.toml", workspace_root.display()),
         ];
         if options.all_targets {
             args.push("--all-targets".to_string());
@@ -265,83 +318,47 @@ impl WatchThread {
         args.extend(options.args.iter().cloned());
 
         let (message_send, message_recv) = unbounded();
-        let enabled = options.enable;
-        let handle = std::thread::spawn(move || {
-            if !enabled {
-                return;
-            }
-
-            let mut command = Command::new("cargo")
-                .args(&args)
-                .stdout(Stdio::piped())
-                .stderr(Stdio::null())
-                .stdin(Stdio::null())
-                .spawn()
-                .expect("couldn't launch cargo");
-
-            // If we trigger an error here, we will do so in the loop instead,
-            // which will break out of the loop, and continue the shutdown
-            let _ = message_send.send(CheckEvent::Begin);
-
-            // We manually read a line at a time, instead of using serde's
-            // stream deserializers, because the deserializer cannot recover
-            // from an error, resulting in it getting stuck, because we try to
-            // be resillient against failures.
-            //
-            // Because cargo only outputs one JSON object per line, we can
-            // simply skip a line if it doesn't parse, which just ignores any
-            // erroneus output.
-            let stdout = BufReader::new(command.stdout.take().unwrap());
-            for line in stdout.lines() {
-                let line = match line {
-                    Ok(line) => line,
-                    Err(err) => {
-                        log::error!("Couldn't read line from cargo: {}", err);
-                        continue;
-                    }
-                };
-
-                let message = serde_json::from_str::<cargo_metadata::Message>(&line);
-                let message = match message {
-                    Ok(message) => message,
-                    Err(err) => {
-                        log::error!(
-                            "Invalid json from cargo check, ignoring ({}): {:?} ",
-                            err,
-                            line
-                        );
-                        continue;
+        let workspace_root = workspace_root.to_owned();
+        let handle = if options.enable {
+            Some(std::thread::spawn(move || {
+                // If we trigger an error here, we will do so in the loop instead,
+                // which will break out of the loop, and continue the shutdown
+                let _ = message_send.send(CheckEvent::Begin);
+
+                let mut child = run_cargo(&args, Some(&workspace_root), |message| {
+                    // Skip certain kinds of messages to only spend time on what's useful
+                    match &message {
+                        Message::CompilerArtifact(artifact) if artifact.fresh => return true,
+                        Message::BuildScriptExecuted(_) => return true,
+                        Message::Unknown => return true,
+                        _ => {}
                     }
-                };
-
-                // Skip certain kinds of messages to only spend time on what's useful
-                match &message {
-                    Message::CompilerArtifact(artifact) if artifact.fresh => continue,
-                    Message::BuildScriptExecuted(_) => continue,
-                    Message::Unknown => continue,
-                    _ => {}
-                }
 
-                match message_send.send(CheckEvent::Msg(message)) {
-                    Ok(()) => {}
-                    Err(_err) => {
-                        // The send channel was closed, so we want to shutdown
-                        break;
-                    }
-                }
-            }
-
-            // We can ignore any error here, as we are already in the progress
-            // of shutting down.
-            let _ = message_send.send(CheckEvent::End);
-
-            // It is okay to ignore the result, as it only errors if the process is already dead
-            let _ = command.kill();
-
-            // Again, we don't care about the exit status so just ignore the result
-            let _ = command.wait();
-        });
-        WatchThread { handle: Some(handle), message_recv }
+                    match message_send.send(CheckEvent::Msg(message)) {
+                        Ok(()) => {}
+                        Err(_err) => {
+                            // The send channel was closed, so we want to shutdown
+                            return false;
+                        }
+                    };
+
+                    true
+                });
+
+                // We can ignore any error here, as we are already in the progress
+                // of shutting down.
+                let _ = message_send.send(CheckEvent::End);
+
+                // It is okay to ignore the result, as it only errors if the process is already dead
+                let _ = child.kill();
+
+                // Again, we don't care about the exit status so just ignore the result
+                let _ = child.wait();
+            }))
+        } else {
+            None
+        };
+        WatchThread { handle, message_recv }
     }
 }
 
diff --git a/crates/ra_db/src/input.rs b/crates/ra_db/src/input.rs
index bde843001..e371f849d 100644
--- a/crates/ra_db/src/input.rs
+++ b/crates/ra_db/src/input.rs
@@ -6,7 +6,11 @@
 //! actual IO. See `vfs` and `project_model` in the `rust-analyzer` crate for how
 //! actual IO is done and lowered to input.
 
-use std::{fmt, ops, str::FromStr};
+use std::{
+    fmt, ops,
+    path::{Path, PathBuf},
+    str::FromStr,
+};
 
 use ra_cfg::CfgOptions;
 use ra_syntax::SmolStr;
@@ -144,7 +148,7 @@ pub struct Env {
 // crate. We store a map to allow remap it to ExternSourceId
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
 pub struct ExternSource {
-    extern_paths: FxHashMap<String, ExternSourceId>,
+    extern_paths: FxHashMap<PathBuf, ExternSourceId>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -294,13 +298,10 @@ impl Env {
 }
 
 impl ExternSource {
-    pub fn extern_path(&self, path: &str) -> Option<(ExternSourceId, RelativePathBuf)> {
+    pub fn extern_path(&self, path: impl AsRef<Path>) -> Option<(ExternSourceId, RelativePathBuf)> {
+        let path = path.as_ref();
         self.extern_paths.iter().find_map(|(root_path, id)| {
-            if path.starts_with(root_path) {
-                let mut rel_path = &path[root_path.len()..];
-                if rel_path.starts_with("/") {
-                    rel_path = &rel_path[1..];
-                }
+            if let Ok(rel_path) = path.strip_prefix(root_path) {
                 let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
                 Some((id.clone(), rel_path))
             } else {
@@ -309,8 +310,8 @@ impl ExternSource {
         })
     }
 
-    pub fn set_extern_path(&mut self, root_path: &str, root: ExternSourceId) {
-        self.extern_paths.insert(root_path.to_owned(), root);
+    pub fn set_extern_path(&mut self, root_path: &Path, root: ExternSourceId) {
+        self.extern_paths.insert(root_path.to_path_buf(), root);
     }
 }
 
diff --git a/crates/ra_project_model/Cargo.toml b/crates/ra_project_model/Cargo.toml
index 6252241bf..22300548a 100644
--- a/crates/ra_project_model/Cargo.toml
+++ b/crates/ra_project_model/Cargo.toml
@@ -16,6 +16,7 @@ cargo_metadata = "0.9.1"
 ra_arena = { path = "../ra_arena" }
 ra_db = { path = "../ra_db" }
 ra_cfg = { path = "../ra_cfg" }
+ra_cargo_watch = { path = "../ra_cargo_watch" }
 
 serde = { version = "1.0.104", features = ["derive"] }
 serde_json = "1.0.48"
diff --git a/crates/ra_project_model/src/cargo_workspace.rs b/crates/ra_project_model/src/cargo_workspace.rs
index 4fea459d5..eeeb10233 100644
--- a/crates/ra_project_model/src/cargo_workspace.rs
+++ b/crates/ra_project_model/src/cargo_workspace.rs
@@ -3,8 +3,9 @@
 use std::path::{Path, PathBuf};
 
 use anyhow::{Context, Result};
-use cargo_metadata::{CargoOpt, MetadataCommand};
+use cargo_metadata::{CargoOpt, Message, MetadataCommand, PackageId};
 use ra_arena::{impl_arena_id, Arena, RawId};
+use ra_cargo_watch::run_cargo;
 use ra_db::Edition;
 use rustc_hash::FxHashMap;
 use serde::Deserialize;
@@ -35,11 +36,19 @@ pub struct CargoFeatures {
     /// List of features to activate.
     /// This will be ignored if `cargo_all_features` is true.
     pub features: Vec<String>,
+
+    /// Runs cargo check on launch to figure out the correct values of OUT_DIR
+    pub load_out_dirs_from_check: bool,
 }
 
 impl Default for CargoFeatures {
     fn default() -> Self {
-        CargoFeatures { no_default_features: false, all_features: true, features: Vec::new() }
+        CargoFeatures {
+            no_default_features: false,
+            all_features: true,
+            features: Vec::new(),
+            load_out_dirs_from_check: false,
+        }
     }
 }
 
@@ -60,6 +69,7 @@ struct PackageData {
     dependencies: Vec<PackageDependency>,
     edition: Edition,
     features: Vec<String>,
+    out_dir: Option<PathBuf>,
 }
 
 #[derive(Debug, Clone)]
@@ -131,6 +141,9 @@ impl Package {
     ) -> impl Iterator<Item = &'a PackageDependency> + 'a {
         ws.packages[self].dependencies.iter()
     }
+    pub fn out_dir(self, ws: &CargoWorkspace) -> Option<&Path> {
+        ws.packages[self].out_dir.as_ref().map(|od| od.as_path())
+    }
 }
 
 impl Target {
@@ -173,6 +186,12 @@ impl CargoWorkspace {
         let meta = meta.exec().with_context(|| {
             format!("Failed to run `cargo metadata --manifest-path {}`", cargo_toml.display())
         })?;
+
+        let mut out_dir_by_id = FxHashMap::default();
+        if cargo_features.load_out_dirs_from_check {
+            out_dir_by_id = load_out_dirs(cargo_toml, cargo_features);
+        }
+
         let mut pkg_by_id = FxHashMap::default();
         let mut packages = Arena::default();
         let mut targets = Arena::default();
@@ -193,6 +212,7 @@ impl CargoWorkspace {
                 edition,
                 dependencies: Vec::new(),
                 features: Vec::new(),
+                out_dir: out_dir_by_id.get(&id).cloned(),
             });
             let pkg_data = &mut packages[pkg];
             pkg_by_id.insert(id, pkg);
@@ -252,3 +272,46 @@ impl CargoWorkspace {
         &self.workspace_root
     }
 }
+
+pub fn load_out_dirs(
+    cargo_toml: &Path,
+    cargo_features: &CargoFeatures,
+) -> FxHashMap<PackageId, PathBuf> {
+    let mut args: Vec<String> = vec![
+        "check".to_string(),
+        "--message-format=json".to_string(),
+        "--manifest-path".to_string(),
+        format!("{}", cargo_toml.display()),
+    ];
+
+    if cargo_features.all_features {
+        args.push("--all-features".to_string());
+    } else if cargo_features.no_default_features {
+        // FIXME: `NoDefaultFeatures` is mutual exclusive with `SomeFeatures`
+        // https://github.com/oli-obk/cargo_metadata/issues/79
+        args.push("--no-default-features".to_string());
+    } else if !cargo_features.features.is_empty() {
+        for feature in &cargo_features.features {
+            args.push(feature.clone());
+        }
+    }
+
+    let mut res = FxHashMap::default();
+    let mut child = run_cargo(&args, cargo_toml.parent(), |message| {
+        match message {
+            Message::BuildScriptExecuted(message) => {
+                let package_id = message.package_id;
+                let out_dir = message.out_dir;
+                res.insert(package_id, out_dir);
+            }
+
+            Message::CompilerArtifact(_) => (),
+            Message::CompilerMessage(_) => (),
+            Message::Unknown => (),
+        }
+        true
+    });
+
+    let _ = child.wait();
+    res
+}
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index 897874813..43f834253 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -150,6 +150,21 @@ impl ProjectWorkspace {
         }
     }
 
+    pub fn out_dirs(&self) -> Vec<PathBuf> {
+        match self {
+            ProjectWorkspace::Json { project: _project } => vec![],
+            ProjectWorkspace::Cargo { cargo, sysroot: _sysroot } => {
+                let mut out_dirs = Vec::with_capacity(cargo.packages().len());
+                for pkg in cargo.packages() {
+                    if let Some(out_dir) = pkg.out_dir(&cargo) {
+                        out_dirs.push(out_dir.to_path_buf());
+                    }
+                }
+                out_dirs
+            }
+        }
+    }
+
     pub fn n_packages(&self) -> usize {
         match self {
             ProjectWorkspace::Json { project } => project.crates.len(),
@@ -162,7 +177,8 @@ impl ProjectWorkspace {
     pub fn to_crate_graph(
         &self,
         default_cfg_options: &CfgOptions,
-        outdirs: &FxHashMap<String, (ExternSourceId, String)>,
+        additional_out_dirs: &FxHashMap<String, PathBuf>,
+        extern_source_roots: &FxHashMap<PathBuf, ExternSourceId>,
         load: &mut dyn FnMut(&Path) -> Option<FileId>,
     ) -> CrateGraph {
         let mut crate_graph = CrateGraph::default();
@@ -237,9 +253,11 @@ impl ProjectWorkspace {
 
                         let mut env = Env::default();
                         let mut extern_source = ExternSource::default();
-                        if let Some((id, path)) = outdirs.get(krate.name(&sysroot)) {
-                            env.set("OUT_DIR", path.clone());
-                            extern_source.set_extern_path(&path, *id);
+                        if let Some(path) = additional_out_dirs.get(krate.name(&sysroot)) {
+                            env.set("OUT_DIR", path.to_string_lossy().to_string());
+                            if let Some(extern_source_id) = extern_source_roots.get(path) {
+                                extern_source.set_extern_path(&path, *extern_source_id);
+                            }
                         }
 
                         let crate_id = crate_graph.add_crate_root(
@@ -292,9 +310,20 @@ impl ProjectWorkspace {
                             };
                             let mut env = Env::default();
                             let mut extern_source = ExternSource::default();
-                            if let Some((id, path)) = outdirs.get(pkg.name(&cargo)) {
-                                env.set("OUT_DIR", path.clone());
-                                extern_source.set_extern_path(&path, *id);
+                            if let Some(out_dir) = dbg!(pkg.out_dir(cargo)) {
+                                env.set("OUT_DIR", out_dir.to_string_lossy().to_string());
+                                if let Some(extern_source_id) =
+                                    dbg!(dbg!(&extern_source_roots).get(out_dir))
+                                {
+                                    extern_source.set_extern_path(&out_dir, *extern_source_id);
+                                }
+                            } else {
+                                if let Some(path) = additional_out_dirs.get(pkg.name(&cargo)) {
+                                    env.set("OUT_DIR", path.to_string_lossy().to_string());
+                                    if let Some(extern_source_id) = extern_source_roots.get(path) {
+                                        extern_source.set_extern_path(&path, *extern_source_id);
+                                    }
+                                }
                             }
                             let crate_id = crate_graph.add_crate_root(
                                 file_id,
diff --git a/crates/rust-analyzer/src/cli/load_cargo.rs b/crates/rust-analyzer/src/cli/load_cargo.rs
index 2ce69c9b3..7d75b991d 100644
--- a/crates/rust-analyzer/src/cli/load_cargo.rs
+++ b/crates/rust-analyzer/src/cli/load_cargo.rs
@@ -54,12 +54,18 @@ pub(crate) fn load_cargo(
 
     // FIXME: outdirs?
     let outdirs = FxHashMap::default();
-
-    let crate_graph = ws.to_crate_graph(&default_cfg_options, &outdirs, &mut |path: &Path| {
-        let vfs_file = vfs.load(path);
-        log::debug!("vfs file {:?} -> {:?}", path, vfs_file);
-        vfs_file.map(vfs_file_to_id)
-    });
+    let extern_source_roots = FxHashMap::default();
+
+    let crate_graph = ws.to_crate_graph(
+        &default_cfg_options,
+        &outdirs,
+        &extern_source_roots,
+        &mut |path: &Path| {
+            let vfs_file = vfs.load(path);
+            log::debug!("vfs file {:?} -> {:?}", path, vfs_file);
+            vfs_file.map(vfs_file_to_id)
+        },
+    );
     log::debug!("crate graph: {:?}", crate_graph);
 
     let source_roots = roots
diff --git a/crates/rust-analyzer/src/world.rs b/crates/rust-analyzer/src/world.rs
index 5743471bf..63e913047 100644
--- a/crates/rust-analyzer/src/world.rs
+++ b/crates/rust-analyzer/src/world.rs
@@ -105,11 +105,15 @@ impl WorldState {
             }));
         }
 
-        let extern_dirs: FxHashSet<_> =
+        let mut extern_dirs: FxHashSet<_> =
             additional_out_dirs.iter().map(|(_, path)| (PathBuf::from(path))).collect();
+        for ws in workspaces.iter() {
+            extern_dirs.extend(ws.out_dirs());
+        }
+
         let mut extern_source_roots = FxHashMap::default();
 
-        roots.extend(additional_out_dirs.iter().map(|(_, path)| {
+        roots.extend(extern_dirs.iter().map(|path| {
             let mut filter = RustPackageFilterBuilder::default().set_member(false);
             for glob in exclude_globs.iter() {
                 filter = filter.exclude(glob.clone());
@@ -148,17 +152,21 @@ impl WorldState {
             vfs_file.map(|f| FileId(f.0))
         };
 
-        let mut outdirs = FxHashMap::default();
-        for (name, path) in additional_out_dirs {
-            let path = PathBuf::from(&path);
-            if let Some(id) = extern_source_roots.get(&path) {
-                outdirs.insert(name, (id.clone(), path.to_string_lossy().replace("\\", "/")));
-            }
-        }
+        let additional_out_dirs: FxHashMap<String, PathBuf> = additional_out_dirs
+            .into_iter()
+            .map(|(name, path)| (name, PathBuf::from(&path)))
+            .collect();
 
         workspaces
             .iter()
-            .map(|ws| ws.to_crate_graph(&default_cfg_options, &outdirs, &mut load))
+            .map(|ws| {
+                ws.to_crate_graph(
+                    &default_cfg_options,
+                    &additional_out_dirs,
+                    &extern_source_roots,
+                    &mut load,
+                )
+            })
             .for_each(|graph| {
                 crate_graph.extend(graph);
             });
diff --git a/editors/code/package.json b/editors/code/package.json
index 48f28b28a..188a2f9ca 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -362,6 +362,11 @@
                     },
                     "default": [],
                     "description": "List of features to activate"
+                },
+                "rust-analyzer.cargoFeatures.loadOutDirsFromCheck": {
+                    "type": "boolean",
+                    "default": false,
+                    "markdownDescription": "Run `cargo check` on startup to get the correct value for package OUT_DIRs"
                 }
             }
         },
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index bd8096dd6..84ec81ecd 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -22,6 +22,7 @@ export interface CargoFeatures {
     noDefaultFeatures: boolean;
     allFeatures: boolean;
     features: string[];
+    loadOutDirsFromCheck: boolean;
 }
 
 export const enum UpdatesChannel {
@@ -204,6 +205,7 @@ export class Config {
     get featureFlags() { return this.cfg.get("featureFlags") as Record<string, boolean>; }
     get additionalOutDirs() { return this.cfg.get("additionalOutDirs") as Record<string, string>; }
     get rustfmtArgs() { return this.cfg.get("rustfmtArgs") as string[]; }
+    get loadOutDirsFromCheck() { return this.cfg.get("loadOutDirsFromCheck") as boolean; }
 
     get cargoWatchOptions(): CargoWatchOptions {
         return {
@@ -219,6 +221,7 @@ export class Config {
             noDefaultFeatures: this.cfg.get("cargoFeatures.noDefaultFeatures") as boolean,
             allFeatures: this.cfg.get("cargoFeatures.allFeatures") as boolean,
             features: this.cfg.get("cargoFeatures.features") as string[],
+            loadOutDirsFromCheck: this.cfg.get("cargoFeatures.loadOutDirsFromCheck") as boolean,
         };
     }