crates/rust-analyzer/src/reload.rs

   1 //! Project loading & configuration updates.
   2 //!
   3 //! This is quite tricky. The main problem is time and changes -- there's no
   4 //! fixed "project" rust-analyzer is working with, "current project" is itself
   5 //! mutable state. For example, when the user edits `Cargo.toml` by adding a new
   6 //! dependency, project model changes. What's more, switching project model is
   7 //! not instantaneous -- it takes time to run `cargo metadata` and (for proc
   8 //! macros) `cargo check`.
   9 //!
  10 //! The main guiding principle here is, as elsewhere in rust-analyzer,
  11 //! robustness. We try not to assume that the project model exists or is
  12 //! correct. Instead, we try to provide a best-effort service. Even if the
  13 //! project is currently loading and we don't have a full project model, we
  14 //! still want to respond to various  requests.
  15 use std::{mem, sync::Arc};
  16
  17 use flycheck::{FlycheckConfig, FlycheckHandle};
  18 use hir::db::DefDatabase;
  19 use ide::Change;
  20 use ide_db::base_db::{
  21     CrateGraph, Env, ProcMacro, ProcMacroExpander, ProcMacroExpansionError, ProcMacroKind,
  22     ProcMacroLoadResult, SourceRoot, VfsPath,
  23 };
  24 use proc_macro_api::{MacroDylib, ProcMacroServer};
  25 use project_model::{ProjectWorkspace, WorkspaceBuildScripts};
  26 use syntax::SmolStr;
  27 use vfs::{file_set::FileSetConfig, AbsPath, AbsPathBuf, ChangeKind};
  28
  29 use crate::{
  30     config::{Config, FilesWatcher, LinkedProject},
  31     global_state::GlobalState,
  32     lsp_ext,
  33     main_loop::Task,
  34     op_queue::Cause,
  35 };
  36
  37 #[derive(Debug)]
  38 pub(crate) enum ProjectWorkspaceProgress {
  39     Begin,
  40     Report(String),
  41     End(Vec<anyhow::Result<ProjectWorkspace>>),
  42 }
  43
  44 #[derive(Debug)]
  45 pub(crate) enum BuildDataProgress {
  46     Begin,
  47     Report(String),
  48     End((Arc<Vec<ProjectWorkspace>>, Vec<anyhow::Result<WorkspaceBuildScripts>>)),
  49 }
  50
  51 impl GlobalState {
  52     pub(crate) fn is_quiescent(&self) -> bool {
  53         !(self.fetch_workspaces_queue.op_in_progress()
  54             || self.fetch_build_data_queue.op_in_progress()
  55             || self.vfs_progress_config_version < self.vfs_config_version
  56             || self.vfs_progress_n_done < self.vfs_progress_n_total)
  57     }
  58
  59     pub(crate) fn update_configuration(&mut self, config: Config) {
  60         let _p = profile::span("GlobalState::update_configuration");
  61         let old_config = mem::replace(&mut self.config, Arc::new(config));
  62         if self.config.lru_capacity() != old_config.lru_capacity() {
  63             self.analysis_host.update_lru_capacity(self.config.lru_capacity());
  64         }
  65         if self.config.linked_projects() != old_config.linked_projects() {
  66             self.fetch_workspaces_queue.request_op("linked projects changed".to_string())
  67         } else if self.config.flycheck() != old_config.flycheck() {
  68             self.reload_flycheck();
  69         }
  70
  71         if self.analysis_host.raw_database().enable_proc_attr_macros()
  72             != self.config.expand_proc_attr_macros()
  73         {
  74             self.analysis_host
  75                 .raw_database_mut()
  76                 .set_enable_proc_attr_macros(self.config.expand_proc_attr_macros());
  77         }
  78     }
  79
  80     pub(crate) fn current_status(&self) -> lsp_ext::ServerStatusParams {
  81         let mut status = lsp_ext::ServerStatusParams {
  82             health: lsp_ext::Health::Ok,
  83             quiescent: self.is_quiescent(),
  84             message: None,
  85         };
  86
  87         if self.proc_macro_changed {
  88             status.health = lsp_ext::Health::Warning;
  89             status.message =
  90                 Some("Reload required due to source changes of a procedural macro.".into())
  91         }
  92         if let Err(_) = self.fetch_build_data_error() {
  93             status.health = lsp_ext::Health::Warning;
  94             status.message =
  95                 Some("Failed to run build scripts of some packages, check the logs.".to_string());
  96         }
  97         if !self.config.cargo_autoreload()
  98             && self.is_quiescent()
  99             && self.fetch_workspaces_queue.op_requested()
 100         {
 101             status.health = lsp_ext::Health::Warning;
 102             status.message = Some("Workspace reload required".to_string())
 103         }
 104
 105         if let Err(error) = self.fetch_workspace_error() {
 106             status.health = lsp_ext::Health::Error;
 107             status.message = Some(error)
 108         }
 109         status
 110     }
 111
 112     pub(crate) fn fetch_workspaces(&mut self, cause: Cause) {
 113         tracing::info!(%cause, "will fetch workspaces");
 114
 115         self.task_pool.handle.spawn_with_sender({
 116             let linked_projects = self.config.linked_projects();
 117             let detached_files = self.config.detached_files().to_vec();
 118             let cargo_config = self.config.cargo();
 119
 120             move |sender| {
 121                 let progress = {
 122                     let sender = sender.clone();
 123                     move |msg| {
 124                         sender
 125                             .send(Task::FetchWorkspace(ProjectWorkspaceProgress::Report(msg)))
 126                             .unwrap()
 127                     }
 128                 };
 129
 130                 sender.send(Task::FetchWorkspace(ProjectWorkspaceProgress::Begin)).unwrap();
 131
 132                 let mut workspaces = linked_projects
 133                     .iter()
 134                     .map(|project| match project {
 135                         LinkedProject::ProjectManifest(manifest) => {
 136                             project_model::ProjectWorkspace::load(
 137                                 manifest.clone(),
 138                                 &cargo_config,
 139                                 &progress,
 140                             )
 141                         }
 142                         LinkedProject::InlineJsonProject(it) => {
 143                             project_model::ProjectWorkspace::load_inline(
 144                                 it.clone(),
 145                                 cargo_config.target.as_deref(),
 146                             )
 147                         }
 148                     })
 149                     .collect::<Vec<_>>();
 150
 151                 if !detached_files.is_empty() {
 152                     workspaces
 153                         .push(project_model::ProjectWorkspace::load_detached_files(detached_files));
 154                 }
 155
 156                 tracing::info!("did fetch workspaces {:?}", workspaces);
 157                 sender
 158                     .send(Task::FetchWorkspace(ProjectWorkspaceProgress::End(workspaces)))
 159                     .unwrap();
 160             }
 161         });
 162     }
 163
 164     pub(crate) fn fetch_build_data(&mut self, cause: Cause) {
 165         tracing::info!(%cause, "will fetch build data");
 166         let workspaces = Arc::clone(&self.workspaces);
 167         let config = self.config.cargo();
 168         self.task_pool.handle.spawn_with_sender(move |sender| {
 169             sender.send(Task::FetchBuildData(BuildDataProgress::Begin)).unwrap();
 170
 171             let progress = {
 172                 let sender = sender.clone();
 173                 move |msg| {
 174                     sender.send(Task::FetchBuildData(BuildDataProgress::Report(msg))).unwrap()
 175                 }
 176             };
 177             let mut res = Vec::new();
 178             for ws in workspaces.iter() {
 179                 res.push(ws.run_build_scripts(&config, &progress));
 180             }
 181             sender.send(Task::FetchBuildData(BuildDataProgress::End((workspaces, res)))).unwrap();
 182         });
 183     }
 184
 185     pub(crate) fn switch_workspaces(&mut self, cause: Cause) {
 186         let _p = profile::span("GlobalState::switch_workspaces");
 187         tracing::info!(%cause, "will switch workspaces");
 188
 189         if let Err(error_message) = self.fetch_workspace_error() {
 190             self.show_and_log_error(error_message, None);
 191             if !self.workspaces.is_empty() {
 192                 // It only makes sense to switch to a partially broken workspace
 193                 // if we don't have any workspace at all yet.
 194                 return;
 195             }
 196         }
 197
 198         if let Err(error) = self.fetch_build_data_error() {
 199             self.show_and_log_error(
 200                 "rust-analyzer failed to run build scripts".to_string(),
 201                 Some(error),
 202             );
 203         }
 204
 205         let workspaces = self
 206             .fetch_workspaces_queue
 207             .last_op_result()
 208             .iter()
 209             .filter_map(|res| res.as_ref().ok().cloned())
 210             .collect::<Vec<_>>();
 211
 212         fn eq_ignore_build_data<'a>(
 213             left: &'a ProjectWorkspace,
 214             right: &'a ProjectWorkspace,
 215         ) -> bool {
 216             let key = |p: &'a ProjectWorkspace| match p {
 217                 ProjectWorkspace::Cargo {
 218                     cargo,
 219                     sysroot,
 220                     rustc,
 221                     rustc_cfg,
 222                     cfg_overrides,
 223
 224                     build_scripts: _,
 225                 } => Some((cargo, sysroot, rustc, rustc_cfg, cfg_overrides)),
 226                 _ => None,
 227             };
 228             match (key(left), key(right)) {
 229                 (Some(lk), Some(rk)) => lk == rk,
 230                 _ => left == right,
 231             }
 232         }
 233
 234         let same_workspaces = workspaces.len() == self.workspaces.len()
 235             && workspaces
 236                 .iter()
 237                 .zip(self.workspaces.iter())
 238                 .all(|(l, r)| eq_ignore_build_data(l, r));
 239
 240         if same_workspaces {
 241             let (workspaces, build_scripts) = self.fetch_build_data_queue.last_op_result();
 242             if Arc::ptr_eq(workspaces, &self.workspaces) {
 243                 tracing::debug!("set build scripts to workspaces");
 244
 245                 let workspaces = workspaces
 246                     .iter()
 247                     .cloned()
 248                     .zip(build_scripts)
 249                     .map(|(mut ws, bs)| {
 250                         ws.set_build_scripts(bs.as_ref().ok().cloned().unwrap_or_default());
 251                         ws
 252                     })
 253                     .collect::<Vec<_>>();
 254
 255                 // Workspaces are the same, but we've updated build data.
 256                 self.workspaces = Arc::new(workspaces);
 257             } else {
 258                 tracing::info!("build scripts do not match the version of the active workspace");
 259                 // Current build scripts do not match the version of the active
 260                 // workspace, so there's nothing for us to update.
 261                 return;
 262             }
 263         } else {
 264             tracing::debug!("abandon build scripts for workspaces");
 265
 266             // Here, we completely changed the workspace (Cargo.toml edit), so
 267             // we don't care about build-script results, they are stale.
 268             self.workspaces = Arc::new(workspaces)
 269         }
 270
 271         if let FilesWatcher::Client = self.config.files().watcher {
 272             let registration_options = lsp_types::DidChangeWatchedFilesRegistrationOptions {
 273                 watchers: self
 274                     .workspaces
 275                     .iter()
 276                     .flat_map(|ws| ws.to_roots())
 277                     .filter(|it| it.is_local)
 278                     .flat_map(|root| {
 279                         root.include.into_iter().flat_map(|it| {
 280                             [
 281                                 format!("{}/**/*.rs", it.display()),
 282                                 format!("{}/**/Cargo.toml", it.display()),
 283                                 format!("{}/**/Cargo.lock", it.display()),
 284                             ]
 285                         })
 286                     })
 287                     .map(|glob_pattern| lsp_types::FileSystemWatcher { glob_pattern, kind: None })
 288                     .collect(),
 289             };
 290             let registration = lsp_types::Registration {
 291                 id: "workspace/didChangeWatchedFiles".to_string(),
 292                 method: "workspace/didChangeWatchedFiles".to_string(),
 293                 register_options: Some(serde_json::to_value(registration_options).unwrap()),
 294             };
 295             self.send_request::<lsp_types::request::RegisterCapability>(
 296                 lsp_types::RegistrationParams { registrations: vec![registration] },
 297                 |_, _| (),
 298             );
 299         }
 300
 301         let mut change = Change::new();
 302
 303         let files_config = self.config.files();
 304         let project_folders = ProjectFolders::new(&self.workspaces, &files_config.exclude);
 305
 306         let standalone_server_name =
 307             format!("rust-analyzer-proc-macro-srv{}", std::env::consts::EXE_SUFFIX);
 308
 309         if self.proc_macro_clients.is_empty() {
 310             if let Some((path, args)) = self.config.proc_macro_srv() {
 311                 self.proc_macro_clients = self
 312                     .workspaces
 313                     .iter()
 314                     .map(|ws| {
 315                         let mut args = args.clone();
 316                         let mut path = path.clone();
 317
 318                         if let ProjectWorkspace::Cargo { sysroot, .. } = ws {
 319                             tracing::info!("Found a cargo workspace...");
 320                             if let Some(sysroot) = sysroot.as_ref() {
 321                                 tracing::info!("Found a cargo workspace with a sysroot...");
 322                                 let server_path =
 323                                     sysroot.root().join("libexec").join(&standalone_server_name);
 324                                 if std::fs::metadata(&server_path).is_ok() {
 325                                     tracing::info!(
 326                                         "And the server exists at {}",
 327                                         server_path.display()
 328                                     );
 329                                     path = server_path;
 330                                     args = vec![];
 331                                 } else {
 332                                     tracing::info!(
 333                                         "And the server does not exist at {}",
 334                                         server_path.display()
 335                                     );
 336                                 }
 337                             }
 338                         }
 339
 340                         tracing::info!(
 341                             "Using proc-macro server at {} with args {:?}",
 342                             path.display(),
 343                             args
 344                         );
 345                         ProcMacroServer::spawn(path.clone(), args.clone()).map_err(|err| {
 346                             let error = format!(
 347                                 "Failed to run proc_macro_srv from path {}, error: {:?}",
 348                                 path.display(),
 349                                 err
 350                             );
 351                             tracing::error!(error);
 352                             error
 353                         })
 354                     })
 355                     .collect();
 356             }
 357         }
 358
 359         let watch = match files_config.watcher {
 360             FilesWatcher::Client => vec![],
 361             FilesWatcher::Server => project_folders.watch,
 362         };
 363         self.vfs_config_version += 1;
 364         self.loader.handle.set_config(vfs::loader::Config {
 365             load: project_folders.load,
 366             watch,
 367             version: self.vfs_config_version,
 368         });
 369
 370         // Create crate graph from all the workspaces
 371         let crate_graph = {
 372             let dummy_replacements = self.config.dummy_replacements();
 373
 374             let vfs = &mut self.vfs.write().0;
 375             let loader = &mut self.loader;
 376             let mem_docs = &self.mem_docs;
 377             let mut load = move |path: &AbsPath| {
 378                 let _p = profile::span("GlobalState::load");
 379                 let vfs_path = vfs::VfsPath::from(path.to_path_buf());
 380                 if !mem_docs.contains(&vfs_path) {
 381                     let contents = loader.handle.load_sync(path);
 382                     vfs.set_file_contents(vfs_path.clone(), contents);
 383                 }
 384                 let res = vfs.file_id(&vfs_path);
 385                 if res.is_none() {
 386                     tracing::warn!("failed to load {}", path.display())
 387                 }
 388                 res
 389             };
 390
 391             let mut crate_graph = CrateGraph::default();
 392             for (idx, ws) in self.workspaces.iter().enumerate() {
 393                 let proc_macro_client = match self.proc_macro_clients.get(idx) {
 394                     Some(res) => res.as_ref().map_err(|e| &**e),
 395                     None => Err("Proc macros are disabled"),
 396                 };
 397                 let mut load_proc_macro = move |crate_name: &str, path: &AbsPath| {
 398                     load_proc_macro(
 399                         proc_macro_client,
 400                         path,
 401                         dummy_replacements.get(crate_name).map(|v| &**v).unwrap_or_default(),
 402                     )
 403                 };
 404                 crate_graph.extend(ws.to_crate_graph(&mut load_proc_macro, &mut load));
 405             }
 406             crate_graph
 407         };
 408         change.set_crate_graph(crate_graph);
 409
 410         self.source_root_config = project_folders.source_root_config;
 411
 412         self.analysis_host.apply_change(change);
 413         self.process_changes();
 414         self.reload_flycheck();
 415         tracing::info!("did switch workspaces");
 416     }
 417
 418     fn fetch_workspace_error(&self) -> Result<(), String> {
 419         let mut buf = String::new();
 420
 421         for ws in self.fetch_workspaces_queue.last_op_result() {
 422             if let Err(err) = ws {
 423                 stdx::format_to!(buf, "rust-analyzer failed to load workspace: {:#}\n", err);
 424             }
 425         }
 426
 427         if buf.is_empty() {
 428             return Ok(());
 429         }
 430
 431         Err(buf)
 432     }
 433
 434     fn fetch_build_data_error(&self) -> Result<(), String> {
 435         let mut buf = String::new();
 436
 437         for ws in &self.fetch_build_data_queue.last_op_result().1 {
 438             match ws {
 439                 Ok(data) => match data.error() {
 440                     Some(stderr) => stdx::format_to!(buf, "{:#}\n", stderr),
 441                     _ => (),
 442                 },
 443                 // io errors
 444                 Err(err) => stdx::format_to!(buf, "{:#}\n", err),
 445             }
 446         }
 447
 448         if buf.is_empty() {
 449             Ok(())
 450         } else {
 451             Err(buf)
 452         }
 453     }
 454
 455     fn reload_flycheck(&mut self) {
 456         let _p = profile::span("GlobalState::reload_flycheck");
 457         let config = match self.config.flycheck() {
 458             Some(it) => it,
 459             None => {
 460                 self.flycheck = Vec::new();
 461                 self.diagnostics.clear_check_all();
 462                 return;
 463             }
 464         };
 465
 466         let sender = self.flycheck_sender.clone();
 467         self.flycheck = self
 468             .workspaces
 469             .iter()
 470             .enumerate()
 471             .filter_map(|(id, w)| match w {
 472                 ProjectWorkspace::Cargo { cargo, .. } => Some((id, cargo.workspace_root())),
 473                 ProjectWorkspace::Json { project, .. } => {
 474                     // Enable flychecks for json projects if a custom flycheck command was supplied
 475                     // in the workspace configuration.
 476                     match config {
 477                         FlycheckConfig::CustomCommand { .. } => Some((id, project.path())),
 478                         _ => None,
 479                     }
 480                 }
 481                 ProjectWorkspace::DetachedFiles { .. } => None,
 482             })
 483             .map(|(id, root)| {
 484                 let sender = sender.clone();
 485                 FlycheckHandle::spawn(
 486                     id,
 487                     Box::new(move |msg| sender.send(msg).unwrap()),
 488                     config.clone(),
 489                     root.to_path_buf(),
 490                 )
 491             })
 492             .collect();
 493     }
 494 }
 495
 496 #[derive(Default)]
 497 pub(crate) struct ProjectFolders {
 498     pub(crate) load: Vec<vfs::loader::Entry>,
 499     pub(crate) watch: Vec<usize>,
 500     pub(crate) source_root_config: SourceRootConfig,
 501 }
 502
 503 impl ProjectFolders {
 504     pub(crate) fn new(
 505         workspaces: &[ProjectWorkspace],
 506         global_excludes: &[AbsPathBuf],
 507     ) -> ProjectFolders {
 508         let mut res = ProjectFolders::default();
 509         let mut fsc = FileSetConfig::builder();
 510         let mut local_filesets = vec![];
 511
 512         for root in workspaces.iter().flat_map(|ws| ws.to_roots()) {
 513             let file_set_roots: Vec<VfsPath> =
 514                 root.include.iter().cloned().map(VfsPath::from).collect();
 515
 516             let entry = {
 517                 let mut dirs = vfs::loader::Directories::default();
 518                 dirs.extensions.push("rs".into());
 519                 dirs.include.extend(root.include);
 520                 dirs.exclude.extend(root.exclude);
 521                 for excl in global_excludes {
 522                     if dirs
 523                         .include
 524                         .iter()
 525                         .any(|incl| incl.starts_with(excl) || excl.starts_with(incl))
 526                     {
 527                         dirs.exclude.push(excl.clone());
 528                     }
 529                 }
 530
 531                 vfs::loader::Entry::Directories(dirs)
 532             };
 533
 534             if root.is_local {
 535                 res.watch.push(res.load.len());
 536             }
 537             res.load.push(entry);
 538
 539             if root.is_local {
 540                 local_filesets.push(fsc.len());
 541             }
 542             fsc.add_file_set(file_set_roots)
 543         }
 544
 545         let fsc = fsc.build();
 546         res.source_root_config = SourceRootConfig { fsc, local_filesets };
 547
 548         res
 549     }
 550 }
 551
 552 #[derive(Default, Debug)]
 553 pub(crate) struct SourceRootConfig {
 554     pub(crate) fsc: FileSetConfig,
 555     pub(crate) local_filesets: Vec<usize>,
 556 }
 557
 558 impl SourceRootConfig {
 559     pub(crate) fn partition(&self, vfs: &vfs::Vfs) -> Vec<SourceRoot> {
 560         let _p = profile::span("SourceRootConfig::partition");
 561         self.fsc
 562             .partition(vfs)
 563             .into_iter()
 564             .enumerate()
 565             .map(|(idx, file_set)| {
 566                 let is_local = self.local_filesets.contains(&idx);
 567                 if is_local {
 568                     SourceRoot::new_local(file_set)
 569                 } else {
 570                     SourceRoot::new_library(file_set)
 571                 }
 572             })
 573             .collect()
 574     }
 575 }
 576
 577 /// Load the proc-macros for the given lib path, replacing all expanders whose names are in `dummy_replace`
 578 /// with an identity dummy expander.
 579 pub(crate) fn load_proc_macro(
 580     server: Result<&ProcMacroServer, &str>,
 581     path: &AbsPath,
 582     dummy_replace: &[Box<str>],
 583 ) -> ProcMacroLoadResult {
 584     let res: Result<Vec<_>, String> = (|| {
 585         let dylib = MacroDylib::new(path.to_path_buf())
 586             .map_err(|io| format!("Proc-macro dylib loading failed: {io}"))?;
 587         let server = server.map_err(ToOwned::to_owned)?;
 588         let vec = server.load_dylib(dylib).map_err(|e| format!("{e}"))?;
 589         if vec.is_empty() {
 590             return Err("proc macro library returned no proc macros".to_string());
 591         }
 592         Ok(vec
 593             .into_iter()
 594             .map(|expander| expander_to_proc_macro(expander, dummy_replace))
 595             .collect())
 596     })();
 597     return match res {
 598         Ok(proc_macros) => {
 599             tracing::info!(
 600                 "Loaded proc-macros for {}: {:?}",
 601                 path.display(),
 602                 proc_macros.iter().map(|it| it.name.clone()).collect::<Vec<_>>()
 603             );
 604             Ok(proc_macros)
 605         }
 606         Err(e) => {
 607             tracing::warn!("proc-macro loading for {} failed: {e}", path.display());
 608             Err(e)
 609         }
 610     };
 611
 612     fn expander_to_proc_macro(
 613         expander: proc_macro_api::ProcMacro,
 614         dummy_replace: &[Box<str>],
 615     ) -> ProcMacro {
 616         let name = SmolStr::from(expander.name());
 617         let kind = match expander.kind() {
 618             proc_macro_api::ProcMacroKind::CustomDerive => ProcMacroKind::CustomDerive,
 619             proc_macro_api::ProcMacroKind::FuncLike => ProcMacroKind::FuncLike,
 620             proc_macro_api::ProcMacroKind::Attr => ProcMacroKind::Attr,
 621         };
 622         let expander: Arc<dyn ProcMacroExpander> =
 623             if dummy_replace.iter().any(|replace| &**replace == name) {
 624                 match kind {
 625                     ProcMacroKind::Attr => Arc::new(IdentityExpander),
 626                     _ => Arc::new(EmptyExpander),
 627                 }
 628             } else {
 629                 Arc::new(Expander(expander))
 630             };
 631         ProcMacro { name, kind, expander }
 632     }
 633
 634     #[derive(Debug)]
 635     struct Expander(proc_macro_api::ProcMacro);
 636
 637     impl ProcMacroExpander for Expander {
 638         fn expand(
 639             &self,
 640             subtree: &tt::Subtree,
 641             attrs: Option<&tt::Subtree>,
 642             env: &Env,
 643         ) -> Result<tt::Subtree, ProcMacroExpansionError> {
 644             let env = env.iter().map(|(k, v)| (k.to_string(), v.to_string())).collect();
 645             match self.0.expand(subtree, attrs, env) {
 646                 Ok(Ok(subtree)) => Ok(subtree),
 647                 Ok(Err(err)) => Err(ProcMacroExpansionError::Panic(err.0)),
 648                 Err(err) => Err(ProcMacroExpansionError::System(err.to_string())),
 649             }
 650         }
 651     }
 652
 653     /// Dummy identity expander, used for attribute proc-macros that are deliberately ignored by the user.
 654     #[derive(Debug)]
 655     struct IdentityExpander;
 656
 657     impl ProcMacroExpander for IdentityExpander {
 658         fn expand(
 659             &self,
 660             subtree: &tt::Subtree,
 661             _: Option<&tt::Subtree>,
 662             _: &Env,
 663         ) -> Result<tt::Subtree, ProcMacroExpansionError> {
 664             Ok(subtree.clone())
 665         }
 666     }
 667
 668     /// Empty expander, used for proc-macros that are deliberately ignored by the user.
 669     #[derive(Debug)]
 670     struct EmptyExpander;
 671
 672     impl ProcMacroExpander for EmptyExpander {
 673         fn expand(
 674             &self,
 675             _: &tt::Subtree,
 676             _: Option<&tt::Subtree>,
 677             _: &Env,
 678         ) -> Result<tt::Subtree, ProcMacroExpansionError> {
 679             Ok(tt::Subtree::default())
 680         }
 681     }
 682 }
 683
 684 pub(crate) fn should_refresh_for_change(path: &AbsPath, change_kind: ChangeKind) -> bool {
 685     const IMPLICIT_TARGET_FILES: &[&str] = &["build.rs", "src/main.rs", "src/lib.rs"];
 686     const IMPLICIT_TARGET_DIRS: &[&str] = &["src/bin", "examples", "tests", "benches"];
 687     let file_name = path.file_name().unwrap_or_default();
 688
 689     if file_name == "Cargo.toml" || file_name == "Cargo.lock" {
 690         return true;
 691     }
 692     if change_kind == ChangeKind::Modify {
 693         return false;
 694     }
 695     if path.extension().unwrap_or_default() != "rs" {
 696         if (file_name == "config.toml" || file_name == "config")
 697             && path.parent().map(|parent| parent.as_ref().ends_with(".cargo")) == Some(true)
 698         {
 699             return true;
 700         }
 701         return false;
 702     }
 703     if IMPLICIT_TARGET_FILES.iter().any(|it| path.as_ref().ends_with(it)) {
 704         return true;
 705     }
 706     let parent = match path.parent() {
 707         Some(it) => it,
 708         None => return false,
 709     };
 710     if IMPLICIT_TARGET_DIRS.iter().any(|it| parent.as_ref().ends_with(it)) {
 711         return true;
 712     }
 713     if file_name == "main.rs" {
 714         let grand_parent = match parent.parent() {
 715             Some(it) => it,
 716             None => return false,
 717         };
 718         if IMPLICIT_TARGET_DIRS.iter().any(|it| grand_parent.as_ref().ends_with(it)) {
 719             return true;
 720         }
 721     }
 722     false
 723 }