src/bootstrap/tool.rs

   1 use std::fs;
   2 use std::env;
   3 use std::path::PathBuf;
   4 use std::process::{Command, exit};
   5 use std::collections::HashSet;
   6
   7 use build_helper::t;
   8
   9 use crate::Mode;
  10 use crate::Compiler;
  11 use crate::builder::{Step, RunConfig, ShouldRun, Builder, Cargo as CargoCommand};
  12 use crate::util::{exe, add_lib_path, CiEnv};
  13 use crate::compile;
  14 use crate::channel::GitInfo;
  15 use crate::channel;
  16 use crate::cache::Interned;
  17 use crate::toolstate::ToolState;
  18
  19 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
  20 pub enum SourceType {
  21     InTree,
  22     Submodule,
  23 }
  24
  25 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
  26 struct ToolBuild {
  27     compiler: Compiler,
  28     target: Interned<String>,
  29     tool: &'static str,
  30     path: &'static str,
  31     mode: Mode,
  32     is_optional_tool: bool,
  33     source_type: SourceType,
  34     extra_features: Vec<String>,
  35 }
  36
  37 impl Step for ToolBuild {
  38     type Output = Option<PathBuf>;
  39
  40     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
  41         run.never()
  42     }
  43
  44     /// Builds a tool in `src/tools`
  45     ///
  46     /// This will build the specified tool with the specified `host` compiler in
  47     /// `stage` into the normal cargo output directory.
  48     fn run(self, builder: &Builder<'_>) -> Option<PathBuf> {
  49         let compiler = self.compiler;
  50         let target = self.target;
  51         let tool = self.tool;
  52         let path = self.path;
  53         let is_optional_tool = self.is_optional_tool;
  54
  55         match self.mode {
  56             Mode::ToolRustc => {
  57                 builder.ensure(compile::Rustc { compiler, target })
  58             }
  59             Mode::ToolStd => {
  60                 builder.ensure(compile::Std { compiler, target })
  61             }
  62             Mode::ToolBootstrap => {} // uses downloaded stage0 compiler libs
  63             _ => panic!("unexpected Mode for tool build")
  64         }
  65
  66         let cargo = prepare_tool_cargo(
  67             builder,
  68             compiler,
  69             self.mode,
  70             target,
  71             "build",
  72             path,
  73             self.source_type,
  74             &self.extra_features,
  75         );
  76
  77         builder.info(&format!("Building stage{} tool {} ({})", compiler.stage, tool, target));
  78         let mut duplicates = Vec::new();
  79         let is_expected = compile::stream_cargo(builder, cargo, vec![], &mut |msg| {
  80             // Only care about big things like the RLS/Cargo for now
  81             match tool {
  82                 | "rls"
  83                 | "cargo"
  84                 | "clippy-driver"
  85                 | "miri"
  86                 | "rustfmt"
  87                 => {}
  88
  89                 _ => return,
  90             }
  91             let (id, features, filenames) = match msg {
  92                 compile::CargoMessage::CompilerArtifact {
  93                     package_id,
  94                     features,
  95                     filenames,
  96                     target: _,
  97                 } => {
  98                     (package_id, features, filenames)
  99                 }
 100                 _ => return,
 101             };
 102             let features = features.iter().map(|s| s.to_string()).collect::<Vec<_>>();
 103
 104             for path in filenames {
 105                 let val = (tool, PathBuf::from(&*path), features.clone());
 106                 // we're only interested in deduplicating rlibs for now
 107                 if val.1.extension().and_then(|s| s.to_str()) != Some("rlib") {
 108                     continue
 109                 }
 110
 111                 // Don't worry about compiles that turn out to be host
 112                 // dependencies or build scripts. To skip these we look for
 113                 // anything that goes in `.../release/deps` but *doesn't* go in
 114                 // `$target/release/deps`. This ensure that outputs in
 115                 // `$target/release` are still considered candidates for
 116                 // deduplication.
 117                 if let Some(parent) = val.1.parent() {
 118                     if parent.ends_with("release/deps") {
 119                         let maybe_target = parent
 120                             .parent()
 121                             .and_then(|p| p.parent())
 122                             .and_then(|p| p.file_name())
 123                             .and_then(|p| p.to_str())
 124                             .unwrap();
 125                         if maybe_target != &*target {
 126                             continue;
 127                         }
 128                     }
 129                 }
 130
 131                 // Record that we've built an artifact for `id`, and if one was
 132                 // already listed then we need to see if we reused the same
 133                 // artifact or produced a duplicate.
 134                 let mut artifacts = builder.tool_artifacts.borrow_mut();
 135                 let prev_artifacts = artifacts
 136                     .entry(target)
 137                     .or_default();
 138                 let prev = match prev_artifacts.get(&*id) {
 139                     Some(prev) => prev,
 140                     None => {
 141                         prev_artifacts.insert(id.to_string(), val);
 142                         continue;
 143                     }
 144                 };
 145                 if prev.1 == val.1 {
 146                     return; // same path, same artifact
 147                 }
 148
 149                 // If the paths are different and one of them *isn't* inside of
 150                 // `release/deps`, then it means it's probably in
 151                 // `$target/release`, or it's some final artifact like
 152                 // `libcargo.rlib`. In these situations Cargo probably just
 153                 // copied it up from `$target/release/deps/libcargo-xxxx.rlib`,
 154                 // so if the features are equal we can just skip it.
 155                 let prev_no_hash = prev.1.parent().unwrap().ends_with("release/deps");
 156                 let val_no_hash = val.1.parent().unwrap().ends_with("release/deps");
 157                 if prev.2 == val.2 || !prev_no_hash || !val_no_hash {
 158                     return;
 159                 }
 160
 161                 // ... and otherwise this looks like we duplicated some sort of
 162                 // compilation, so record it to generate an error later.
 163                 duplicates.push((
 164                     id.to_string(),
 165                     val,
 166                     prev.clone(),
 167                 ));
 168             }
 169         });
 170
 171         if is_expected && !duplicates.is_empty() {
 172             println!("duplicate artifacts found when compiling a tool, this \
 173                       typically means that something was recompiled because \
 174                       a transitive dependency has different features activated \
 175                       than in a previous build:\n");
 176             println!("the following dependencies are duplicated although they \
 177                       have the same features enabled:");
 178             for (id, cur, prev) in duplicates.drain_filter(|(_, cur, prev)| cur.2 == prev.2) {
 179                 println!("  {}", id);
 180                 // same features
 181                 println!("    `{}` ({:?})\n    `{}` ({:?})", cur.0, cur.1, prev.0, prev.1);
 182             }
 183             println!("the following dependencies have different features:");
 184             for (id, cur, prev) in duplicates {
 185                 println!("  {}", id);
 186                 let cur_features: HashSet<_> = cur.2.into_iter().collect();
 187                 let prev_features: HashSet<_> = prev.2.into_iter().collect();
 188                 println!("    `{}` additionally enabled features {:?} at {:?}",
 189                          cur.0, &cur_features - &prev_features, cur.1);
 190                 println!("    `{}` additionally enabled features {:?} at {:?}",
 191                          prev.0, &prev_features - &cur_features, prev.1);
 192             }
 193             println!();
 194             println!("to fix this you will probably want to edit the local \
 195                       src/tools/rustc-workspace-hack/Cargo.toml crate, as \
 196                       that will update the dependency graph to ensure that \
 197                       these crates all share the same feature set");
 198             panic!("tools should not compile multiple copies of the same crate");
 199         }
 200
 201         builder.save_toolstate(tool, if is_expected {
 202             ToolState::TestFail
 203         } else {
 204             ToolState::BuildFail
 205         });
 206
 207         if !is_expected {
 208             if !is_optional_tool {
 209                 exit(1);
 210             } else {
 211                 None
 212             }
 213         } else {
 214             let cargo_out = builder.cargo_out(compiler, self.mode, target)
 215                 .join(exe(tool, &compiler.host));
 216             let bin = builder.tools_dir(compiler).join(exe(tool, &compiler.host));
 217             builder.copy(&cargo_out, &bin);
 218             Some(bin)
 219         }
 220     }
 221 }
 222
 223 pub fn prepare_tool_cargo(
 224     builder: &Builder<'_>,
 225     compiler: Compiler,
 226     mode: Mode,
 227     target: Interned<String>,
 228     command: &'static str,
 229     path: &'static str,
 230     source_type: SourceType,
 231     extra_features: &[String],
 232 ) -> CargoCommand {
 233     let mut cargo = builder.cargo(compiler, mode, target, command);
 234     let dir = builder.src.join(path);
 235     cargo.arg("--manifest-path").arg(dir.join("Cargo.toml"));
 236
 237     if source_type == SourceType::Submodule {
 238         cargo.env("RUSTC_EXTERNAL_TOOL", "1");
 239     }
 240
 241     let mut features = extra_features.iter().cloned().collect::<Vec<_>>();
 242     if builder.build.config.cargo_native_static {
 243         if path.ends_with("cargo") ||
 244             path.ends_with("rls") ||
 245             path.ends_with("clippy") ||
 246             path.ends_with("miri") ||
 247             path.ends_with("rustfmt")
 248         {
 249             cargo.env("LIBZ_SYS_STATIC", "1");
 250             features.push("rustc-workspace-hack/all-static".to_string());
 251         }
 252     }
 253
 254     // if tools are using lzma we want to force the build script to build its
 255     // own copy
 256     cargo.env("LZMA_API_STATIC", "1");
 257
 258     cargo.env("CFG_RELEASE_CHANNEL", &builder.config.channel);
 259     cargo.env("CFG_VERSION", builder.rust_version());
 260     cargo.env("CFG_RELEASE_NUM", channel::CFG_RELEASE_NUM);
 261
 262     let info = GitInfo::new(builder.config.ignore_git, &dir);
 263     if let Some(sha) = info.sha() {
 264         cargo.env("CFG_COMMIT_HASH", sha);
 265     }
 266     if let Some(sha_short) = info.sha_short() {
 267         cargo.env("CFG_SHORT_COMMIT_HASH", sha_short);
 268     }
 269     if let Some(date) = info.commit_date() {
 270         cargo.env("CFG_COMMIT_DATE", date);
 271     }
 272     if !features.is_empty() {
 273         cargo.arg("--features").arg(&features.join(", "));
 274     }
 275     cargo
 276 }
 277
 278 fn rustbook_features() -> Vec<String> {
 279     let mut features = Vec::new();
 280
 281     // Due to CI budged and risk of spurious failures we want to limit jobs running this check.
 282     // At same time local builds should run it regardless of the platform.
 283     // `CiEnv::None` means it's local build and `CHECK_LINKS` is defined in x86_64-gnu-tools to
 284     // explicitly enable it on single job
 285     if CiEnv::current() == CiEnv::None || env::var("CHECK_LINKS").is_ok() {
 286         features.push("linkcheck".to_string());
 287     }
 288
 289     features
 290 }
 291
 292 macro_rules! bootstrap_tool {
 293     ($(
 294         $name:ident, $path:expr, $tool_name:expr
 295         $(,llvm_tools = $llvm:expr)*
 296         $(,is_external_tool = $external:expr)*
 297         $(,features = $features:expr)*
 298         ;
 299     )+) => {
 300         #[derive(Copy, PartialEq, Eq, Clone)]
 301         pub enum Tool {
 302             $(
 303                 $name,
 304             )+
 305         }
 306
 307         impl Tool {
 308             /// Whether this tool requires LLVM to run
 309             pub fn uses_llvm_tools(&self) -> bool {
 310                 match self {
 311                     $(Tool::$name => false $(|| $llvm)*,)+
 312                 }
 313             }
 314         }
 315
 316         impl<'a> Builder<'a> {
 317             pub fn tool_exe(&self, tool: Tool) -> PathBuf {
 318                 match tool {
 319                     $(Tool::$name =>
 320                         self.ensure($name {
 321                             compiler: self.compiler(0, self.config.build),
 322                             target: self.config.build,
 323                         }),
 324                     )+
 325                 }
 326             }
 327         }
 328
 329         $(
 330             #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 331         pub struct $name {
 332             pub compiler: Compiler,
 333             pub target: Interned<String>,
 334         }
 335
 336         impl Step for $name {
 337             type Output = PathBuf;
 338
 339             fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
 340                 run.path($path)
 341             }
 342
 343             fn make_run(run: RunConfig<'_>) {
 344                 run.builder.ensure($name {
 345                     // snapshot compiler
 346                     compiler: run.builder.compiler(0, run.builder.config.build),
 347                     target: run.target,
 348                 });
 349             }
 350
 351             fn run(self, builder: &Builder<'_>) -> PathBuf {
 352                 builder.ensure(ToolBuild {
 353                     compiler: self.compiler,
 354                     target: self.target,
 355                     tool: $tool_name,
 356                     mode: Mode::ToolBootstrap,
 357                     path: $path,
 358                     is_optional_tool: false,
 359                     source_type: if false $(|| $external)* {
 360                         SourceType::Submodule
 361                     } else {
 362                         SourceType::InTree
 363                     },
 364                     extra_features: {
 365                         // FIXME(#60643): avoid this lint by using `_`
 366                         let mut _tmp = Vec::new();
 367                         $(_tmp.extend($features);)*
 368                         _tmp
 369                     },
 370                 }).expect("expected to build -- essential tool")
 371             }
 372         }
 373         )+
 374     }
 375 }
 376
 377 bootstrap_tool!(
 378     Rustbook, "src/tools/rustbook", "rustbook", features = rustbook_features();
 379     UnstableBookGen, "src/tools/unstable-book-gen", "unstable-book-gen";
 380     Tidy, "src/tools/tidy", "tidy";
 381     Linkchecker, "src/tools/linkchecker", "linkchecker";
 382     CargoTest, "src/tools/cargotest", "cargotest";
 383     Compiletest, "src/tools/compiletest", "compiletest", llvm_tools = true;
 384     BuildManifest, "src/tools/build-manifest", "build-manifest";
 385     RemoteTestClient, "src/tools/remote-test-client", "remote-test-client";
 386     RustInstaller, "src/tools/rust-installer", "fabricate", is_external_tool = true;
 387     RustdocTheme, "src/tools/rustdoc-themes", "rustdoc-themes";
 388 );
 389
 390 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 391 pub struct ErrorIndex {
 392     pub compiler: Compiler,
 393 }
 394
 395 impl ErrorIndex {
 396     pub fn command(builder: &Builder<'_>, compiler: Compiler) -> Command {
 397         let mut cmd = Command::new(builder.ensure(ErrorIndex {
 398             compiler
 399         }));
 400         add_lib_path(
 401             vec![PathBuf::from(&builder.sysroot_libdir(compiler, compiler.host))],
 402             &mut cmd,
 403         );
 404         cmd
 405     }
 406 }
 407
 408 impl Step for ErrorIndex {
 409     type Output = PathBuf;
 410
 411     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
 412         run.path("src/tools/error_index_generator")
 413     }
 414
 415     fn make_run(run: RunConfig<'_>) {
 416         // Compile the error-index in the same stage as rustdoc to avoid
 417         // recompiling rustdoc twice if we can.
 418         let stage = if run.builder.top_stage >= 2 { run.builder.top_stage } else { 0 };
 419         run.builder.ensure(ErrorIndex {
 420             compiler: run.builder.compiler(stage, run.builder.config.build),
 421         });
 422     }
 423
 424     fn run(self, builder: &Builder<'_>) -> PathBuf {
 425         builder.ensure(ToolBuild {
 426             compiler: self.compiler,
 427             target: self.compiler.host,
 428             tool: "error_index_generator",
 429             mode: Mode::ToolRustc,
 430             path: "src/tools/error_index_generator",
 431             is_optional_tool: false,
 432             source_type: SourceType::InTree,
 433             extra_features: Vec::new(),
 434         }).expect("expected to build -- essential tool")
 435     }
 436 }
 437
 438 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 439 pub struct RemoteTestServer {
 440     pub compiler: Compiler,
 441     pub target: Interned<String>,
 442 }
 443
 444 impl Step for RemoteTestServer {
 445     type Output = PathBuf;
 446
 447     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
 448         run.path("src/tools/remote-test-server")
 449     }
 450
 451     fn make_run(run: RunConfig<'_>) {
 452         run.builder.ensure(RemoteTestServer {
 453             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 454             target: run.target,
 455         });
 456     }
 457
 458     fn run(self, builder: &Builder<'_>) -> PathBuf {
 459         builder.ensure(ToolBuild {
 460             compiler: self.compiler,
 461             target: self.target,
 462             tool: "remote-test-server",
 463             mode: Mode::ToolStd,
 464             path: "src/tools/remote-test-server",
 465             is_optional_tool: false,
 466             source_type: SourceType::InTree,
 467             extra_features: Vec::new(),
 468         }).expect("expected to build -- essential tool")
 469     }
 470 }
 471
 472 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 473 pub struct Rustdoc {
 474     /// This should only ever be 0 or 2.
 475     /// We sometimes want to reference the "bootstrap" rustdoc, which is why this option is here.
 476     pub compiler: Compiler,
 477 }
 478
 479 impl Step for Rustdoc {
 480     type Output = PathBuf;
 481     const DEFAULT: bool = true;
 482     const ONLY_HOSTS: bool = true;
 483
 484     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
 485         run.path("src/tools/rustdoc")
 486     }
 487
 488     fn make_run(run: RunConfig<'_>) {
 489         run.builder.ensure(Rustdoc {
 490             compiler: run.builder.compiler(run.builder.top_stage, run.host),
 491         });
 492     }
 493
 494     fn run(self, builder: &Builder<'_>) -> PathBuf {
 495         let target_compiler = self.compiler;
 496         if target_compiler.stage == 0 {
 497             if !target_compiler.is_snapshot(builder) {
 498                 panic!("rustdoc in stage 0 must be snapshot rustdoc");
 499             }
 500             return builder.initial_rustc.with_file_name(exe("rustdoc", &target_compiler.host));
 501         }
 502         let target = target_compiler.host;
 503         // Similar to `compile::Assemble`, build with the previous stage's compiler. Otherwise
 504         // we'd have stageN/bin/rustc and stageN/bin/rustdoc be effectively different stage
 505         // compilers, which isn't what we want. Rustdoc should be linked in the same way as the
 506         // rustc compiler it's paired with, so it must be built with the previous stage compiler.
 507         let build_compiler = builder.compiler(target_compiler.stage - 1, builder.config.build);
 508
 509         // The presence of `target_compiler` ensures that the necessary libraries (codegen backends,
 510         // compiler libraries, ...) are built. Rustdoc does not require the presence of any
 511         // libraries within sysroot_libdir (i.e., rustlib), though doctests may want it (since
 512         // they'll be linked to those libraries). As such, don't explicitly `ensure` any additional
 513         // libraries here. The intuition here is that If we've built a compiler, we should be able
 514         // to build rustdoc.
 515
 516         let cargo = prepare_tool_cargo(
 517             builder,
 518             build_compiler,
 519             Mode::ToolRustc,
 520             target,
 521             "build",
 522             "src/tools/rustdoc",
 523             SourceType::InTree,
 524             &[],
 525         );
 526
 527         builder.info(&format!("Building rustdoc for stage{} ({})",
 528             target_compiler.stage, target_compiler.host));
 529         builder.run(&mut cargo.into());
 530
 531         // Cargo adds a number of paths to the dylib search path on windows, which results in
 532         // the wrong rustdoc being executed. To avoid the conflicting rustdocs, we name the "tool"
 533         // rustdoc a different name.
 534         let tool_rustdoc = builder.cargo_out(build_compiler, Mode::ToolRustc, target)
 535             .join(exe("rustdoc_tool_binary", &target_compiler.host));
 536
 537         // don't create a stage0-sysroot/bin directory.
 538         if target_compiler.stage > 0 {
 539             let sysroot = builder.sysroot(target_compiler);
 540             let bindir = sysroot.join("bin");
 541             t!(fs::create_dir_all(&bindir));
 542             let bin_rustdoc = bindir.join(exe("rustdoc", &*target_compiler.host));
 543             let _ = fs::remove_file(&bin_rustdoc);
 544             builder.copy(&tool_rustdoc, &bin_rustdoc);
 545             bin_rustdoc
 546         } else {
 547             tool_rustdoc
 548         }
 549     }
 550 }
 551
 552 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 553 pub struct Cargo {
 554     pub compiler: Compiler,
 555     pub target: Interned<String>,
 556 }
 557
 558 impl Step for Cargo {
 559     type Output = PathBuf;
 560     const DEFAULT: bool = true;
 561     const ONLY_HOSTS: bool = true;
 562
 563     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
 564         let builder = run.builder;
 565         run.path("src/tools/cargo").default_condition(builder.config.extended)
 566     }
 567
 568     fn make_run(run: RunConfig<'_>) {
 569         run.builder.ensure(Cargo {
 570             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 571             target: run.target,
 572         });
 573     }
 574
 575     fn run(self, builder: &Builder<'_>) -> PathBuf {
 576         builder.ensure(ToolBuild {
 577             compiler: self.compiler,
 578             target: self.target,
 579             tool: "cargo",
 580             mode: Mode::ToolRustc,
 581             path: "src/tools/cargo",
 582             is_optional_tool: false,
 583             source_type: SourceType::Submodule,
 584             extra_features: Vec::new(),
 585         }).expect("expected to build -- essential tool")
 586     }
 587 }
 588
 589 macro_rules! tool_extended {
 590     (($sel:ident, $builder:ident),
 591        $($name:ident,
 592        $toolstate:ident,
 593        $path:expr,
 594        $tool_name:expr,
 595        $extra_deps:block;)+) => {
 596         $(
 597             #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 598         pub struct $name {
 599             pub compiler: Compiler,
 600             pub target: Interned<String>,
 601             pub extra_features: Vec<String>,
 602         }
 603
 604         impl Step for $name {
 605             type Output = Option<PathBuf>;
 606             const DEFAULT: bool = true;
 607             const ONLY_HOSTS: bool = true;
 608
 609             fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
 610                 let builder = run.builder;
 611                 run.path($path).default_condition(builder.config.extended)
 612             }
 613
 614             fn make_run(run: RunConfig<'_>) {
 615                 run.builder.ensure($name {
 616                     compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 617                     target: run.target,
 618                     extra_features: Vec::new(),
 619                 });
 620             }
 621
 622             #[allow(unused_mut)]
 623             fn run(mut $sel, $builder: &Builder<'_>) -> Option<PathBuf> {
 624                 $extra_deps
 625                 $builder.ensure(ToolBuild {
 626                     compiler: $sel.compiler,
 627                     target: $sel.target,
 628                     tool: $tool_name,
 629                     mode: Mode::ToolRustc,
 630                     path: $path,
 631                     extra_features: $sel.extra_features,
 632                     is_optional_tool: true,
 633                     source_type: SourceType::Submodule,
 634                 })
 635             }
 636         }
 637         )+
 638     }
 639 }
 640
 641 tool_extended!((self, builder),
 642     Cargofmt, rustfmt, "src/tools/rustfmt", "cargo-fmt", {};
 643     CargoClippy, clippy, "src/tools/clippy", "cargo-clippy", {};
 644     Clippy, clippy, "src/tools/clippy", "clippy-driver", {};
 645     Miri, miri, "src/tools/miri", "miri", {};
 646     CargoMiri, miri, "src/tools/miri", "cargo-miri", {};
 647     Rls, rls, "src/tools/rls", "rls", {
 648         let clippy = builder.ensure(Clippy {
 649             compiler: self.compiler,
 650             target: self.target,
 651             extra_features: Vec::new(),
 652         });
 653         if clippy.is_some() {
 654             self.extra_features.push("clippy".to_owned());
 655         }
 656     };
 657     Rustfmt, rustfmt, "src/tools/rustfmt", "rustfmt", {};
 658 );
 659
 660 impl<'a> Builder<'a> {
 661     /// Gets a `Command` which is ready to run `tool` in `stage` built for
 662     /// `host`.
 663     pub fn tool_cmd(&self, tool: Tool) -> Command {
 664         let mut cmd = Command::new(self.tool_exe(tool));
 665         let compiler = self.compiler(0, self.config.build);
 666         let host = &compiler.host;
 667         // Prepares the `cmd` provided to be able to run the `compiler` provided.
 668         //
 669         // Notably this munges the dynamic library lookup path to point to the
 670         // right location to run `compiler`.
 671         let mut lib_paths: Vec<PathBuf> = vec![
 672             self.build.rustc_snapshot_libdir(),
 673             self.cargo_out(compiler, Mode::ToolBootstrap, *host).join("deps"),
 674         ];
 675
 676         // On MSVC a tool may invoke a C compiler (e.g., compiletest in run-make
 677         // mode) and that C compiler may need some extra PATH modification. Do
 678         // so here.
 679         if compiler.host.contains("msvc") {
 680             let curpaths = env::var_os("PATH").unwrap_or_default();
 681             let curpaths = env::split_paths(&curpaths).collect::<Vec<_>>();
 682             for &(ref k, ref v) in self.cc[&compiler.host].env() {
 683                 if k != "PATH" {
 684                     continue
 685                 }
 686                 for path in env::split_paths(v) {
 687                     if !curpaths.contains(&path) {
 688                         lib_paths.push(path);
 689                     }
 690                 }
 691             }
 692         }
 693
 694         add_lib_path(lib_paths, &mut cmd);
 695         cmd
 696     }
 697 }