src/bootstrap/tool.rs

   1 // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use std::fs;
  12 use std::env;
  13 use std::iter;
  14 use std::path::PathBuf;
  15 use std::process::{Command, exit};
  16 use std::collections::HashSet;
  17
  18 use Mode;
  19 use Compiler;
  20 use builder::{Step, RunConfig, ShouldRun, Builder};
  21 use util::{exe, add_lib_path};
  22 use compile;
  23 use native;
  24 use channel::GitInfo;
  25 use channel;
  26 use cache::Interned;
  27 use toolstate::ToolState;
  28
  29 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
  30 pub enum SourceType {
  31     InTree,
  32     Submodule,
  33 }
  34
  35 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
  36 struct ToolBuild {
  37     compiler: Compiler,
  38     target: Interned<String>,
  39     tool: &'static str,
  40     path: &'static str,
  41     mode: Mode,
  42     is_optional_tool: bool,
  43     source_type: SourceType,
  44     extra_features: Vec<String>,
  45 }
  46
  47 impl Step for ToolBuild {
  48     type Output = Option<PathBuf>;
  49
  50     fn should_run(run: ShouldRun) -> ShouldRun {
  51         run.never()
  52     }
  53
  54     /// Build a tool in `src/tools`
  55     ///
  56     /// This will build the specified tool with the specified `host` compiler in
  57     /// `stage` into the normal cargo output directory.
  58     fn run(self, builder: &Builder) -> Option<PathBuf> {
  59         let compiler = self.compiler;
  60         let target = self.target;
  61         let tool = self.tool;
  62         let path = self.path;
  63         let is_optional_tool = self.is_optional_tool;
  64
  65         match self.mode {
  66             Mode::ToolRustc => {
  67                 builder.ensure(compile::Rustc { compiler, target })
  68             }
  69             Mode::ToolStd => {
  70                 builder.ensure(compile::Std { compiler, target })
  71             }
  72             Mode::ToolBootstrap => {} // uses downloaded stage0 compiler libs
  73             _ => panic!("unexpected Mode for tool build")
  74         }
  75
  76         let mut cargo = prepare_tool_cargo(
  77             builder,
  78             compiler,
  79             self.mode,
  80             target,
  81             "build",
  82             path,
  83             self.source_type,
  84             &self.extra_features,
  85         );
  86
  87         let _folder = builder.fold_output(|| format!("stage{}-{}", compiler.stage, tool));
  88         builder.info(&format!("Building stage{} tool {} ({})", compiler.stage, tool, target));
  89         let mut duplicates = Vec::new();
  90         let is_expected = compile::stream_cargo(builder, &mut cargo, vec![], &mut |msg| {
  91             // Only care about big things like the RLS/Cargo for now
  92             match tool {
  93                 | "rls"
  94                 | "cargo"
  95                 | "clippy-driver"
  96                 => {}
  97
  98                 _ => return,
  99             }
 100             let (id, features, filenames) = match msg {
 101                 compile::CargoMessage::CompilerArtifact {
 102                     package_id,
 103                     features,
 104                     filenames
 105                 } => {
 106                     (package_id, features, filenames)
 107                 }
 108                 _ => return,
 109             };
 110             let features = features.iter().map(|s| s.to_string()).collect::<Vec<_>>();
 111
 112             for path in filenames {
 113                 let val = (tool, PathBuf::from(&*path), features.clone());
 114                 // we're only interested in deduplicating rlibs for now
 115                 if val.1.extension().and_then(|s| s.to_str()) != Some("rlib") {
 116                     continue
 117                 }
 118
 119                 // Don't worry about libs that turn out to be host dependencies
 120                 // or build scripts, we only care about target dependencies that
 121                 // are in `deps`.
 122                 if let Some(maybe_target) = val.1
 123                     .parent()                   // chop off file name
 124                     .and_then(|p| p.parent())   // chop off `deps`
 125                     .and_then(|p| p.parent())   // chop off `release`
 126                     .and_then(|p| p.file_name())
 127                     .and_then(|p| p.to_str())
 128                 {
 129                     if maybe_target != &*target {
 130                         continue
 131                     }
 132                 }
 133
 134                 let mut artifacts = builder.tool_artifacts.borrow_mut();
 135                 let prev_artifacts = artifacts
 136                     .entry(target)
 137                     .or_default();
 138                 if let Some(prev) = prev_artifacts.get(&*id) {
 139                     if prev.1 != val.1 {
 140                         duplicates.push((
 141                             id.to_string(),
 142                             val,
 143                             prev.clone(),
 144                         ));
 145                     }
 146                     return
 147                 }
 148                 prev_artifacts.insert(id.to_string(), val);
 149             }
 150         });
 151
 152         if is_expected && !duplicates.is_empty() {
 153             println!("duplicate artfacts found when compiling a tool, this \
 154                       typically means that something was recompiled because \
 155                       a transitive dependency has different features activated \
 156                       than in a previous build:\n");
 157             println!("the following dependencies are duplicated although they \
 158                       have the same features enabled:");
 159             for (id, cur, prev) in duplicates.drain_filter(|(_, cur, prev)| cur.2 == prev.2) {
 160                 println!("  {}", id);
 161                 // same features
 162                 println!("    `{}` ({:?})\n    `{}` ({:?})", cur.0, cur.1, prev.0, prev.1);
 163             }
 164             println!("the following dependencies have different features:");
 165             for (id, cur, prev) in duplicates {
 166                 println!("  {}", id);
 167                 let cur_features: HashSet<_> = cur.2.into_iter().collect();
 168                 let prev_features: HashSet<_> = prev.2.into_iter().collect();
 169                 println!("    `{}` additionally enabled features {:?} at {:?}",
 170                          cur.0, &cur_features - &prev_features, cur.1);
 171                 println!("    `{}` additionally enabled features {:?} at {:?}",
 172                          prev.0, &prev_features - &cur_features, prev.1);
 173             }
 174             println!();
 175             println!("to fix this you will probably want to edit the local \
 176                       src/tools/rustc-workspace-hack/Cargo.toml crate, as \
 177                       that will update the dependency graph to ensure that \
 178                       these crates all share the same feature set");
 179             panic!("tools should not compile multiple copies of the same crate");
 180         }
 181
 182         builder.save_toolstate(tool, if is_expected {
 183             ToolState::TestFail
 184         } else {
 185             ToolState::BuildFail
 186         });
 187
 188         if !is_expected {
 189             if !is_optional_tool {
 190                 exit(1);
 191             } else {
 192                 None
 193             }
 194         } else {
 195             let cargo_out = builder.cargo_out(compiler, self.mode, target)
 196                 .join(exe(tool, &compiler.host));
 197             let bin = builder.tools_dir(compiler).join(exe(tool, &compiler.host));
 198             builder.copy(&cargo_out, &bin);
 199             Some(bin)
 200         }
 201     }
 202 }
 203
 204 pub fn prepare_tool_cargo(
 205     builder: &Builder,
 206     compiler: Compiler,
 207     mode: Mode,
 208     target: Interned<String>,
 209     command: &'static str,
 210     path: &'static str,
 211     source_type: SourceType,
 212     extra_features: &[String],
 213 ) -> Command {
 214     let mut cargo = builder.cargo(compiler, mode, target, command);
 215     let dir = builder.src.join(path);
 216     cargo.arg("--manifest-path").arg(dir.join("Cargo.toml"));
 217
 218     // We don't want to build tools dynamically as they'll be running across
 219     // stages and such and it's just easier if they're not dynamically linked.
 220     cargo.env("RUSTC_NO_PREFER_DYNAMIC", "1");
 221
 222     if source_type == SourceType::Submodule {
 223         cargo.env("RUSTC_EXTERNAL_TOOL", "1");
 224     }
 225
 226     let mut features = extra_features.iter().cloned().collect::<Vec<_>>();
 227     if builder.build.config.cargo_native_static {
 228         if path.ends_with("cargo") ||
 229             path.ends_with("rls") ||
 230             path.ends_with("clippy") ||
 231             path.ends_with("rustfmt")
 232         {
 233             cargo.env("LIBZ_SYS_STATIC", "1");
 234             features.push("rustc-workspace-hack/all-static".to_string());
 235         }
 236     }
 237
 238     // if tools are using lzma we want to force the build script to build its
 239     // own copy
 240     cargo.env("LZMA_API_STATIC", "1");
 241
 242     cargo.env("CFG_RELEASE_CHANNEL", &builder.config.channel);
 243     cargo.env("CFG_VERSION", builder.rust_version());
 244     cargo.env("CFG_RELEASE_NUM", channel::CFG_RELEASE_NUM);
 245
 246     let info = GitInfo::new(&builder.config, &dir);
 247     if let Some(sha) = info.sha() {
 248         cargo.env("CFG_COMMIT_HASH", sha);
 249     }
 250     if let Some(sha_short) = info.sha_short() {
 251         cargo.env("CFG_SHORT_COMMIT_HASH", sha_short);
 252     }
 253     if let Some(date) = info.commit_date() {
 254         cargo.env("CFG_COMMIT_DATE", date);
 255     }
 256     if !features.is_empty() {
 257         cargo.arg("--features").arg(&features.join(", "));
 258     }
 259     cargo
 260 }
 261
 262 macro_rules! tool {
 263     ($(
 264         $name:ident, $path:expr, $tool_name:expr, $mode:expr
 265         $(,llvm_tools = $llvm:expr)*
 266         $(,is_external_tool = $external:expr)*
 267         $(,cargo_test_root = $cargo_test_root:expr)*
 268         ;
 269     )+) => {
 270         #[derive(Copy, PartialEq, Eq, Clone)]
 271         pub enum Tool {
 272             $(
 273                 $name,
 274             )+
 275         }
 276
 277         impl Tool {
 278             pub fn get_mode(&self) -> Mode {
 279                 let mode = match self {
 280                     $(Tool::$name => $mode,)+
 281                 };
 282                 mode
 283             }
 284
 285             /// Whether this tool requires LLVM to run
 286             pub fn uses_llvm_tools(&self) -> bool {
 287                 match self {
 288                     $(Tool::$name => false $(|| $llvm)*,)+
 289                 }
 290             }
 291
 292             /// Whether this tool requires may run Cargo for test crates,
 293             /// which currently needs setting the environment variable
 294             /// `__CARGO_TEST_ROOT` to separate it from the workspace.
 295             pub fn needs_cargo_test_root(&self) -> bool {
 296                 match self {
 297                     $(Tool::$name => false $(|| $cargo_test_root)*,)+
 298                 }
 299             }
 300         }
 301
 302         impl<'a> Builder<'a> {
 303             pub fn tool_exe(&self, tool: Tool) -> PathBuf {
 304                 let stage = self.tool_default_stage(tool);
 305                 match tool {
 306                     $(Tool::$name =>
 307                         self.ensure($name {
 308                             compiler: self.compiler(stage, self.config.build),
 309                             target: self.config.build,
 310                         }),
 311                     )+
 312                 }
 313             }
 314
 315             pub fn tool_default_stage(&self, tool: Tool) -> u32 {
 316                 // Compile the error-index in the same stage as rustdoc to avoid
 317                 // recompiling rustdoc twice if we can. Otherwise compile
 318                 // everything else in stage0 as there's no need to rebootstrap
 319                 // everything.
 320                 match tool {
 321                     Tool::ErrorIndex if self.top_stage >= 2 => self.top_stage,
 322                     _ => 0,
 323                 }
 324             }
 325         }
 326
 327         $(
 328             #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 329         pub struct $name {
 330             pub compiler: Compiler,
 331             pub target: Interned<String>,
 332         }
 333
 334         impl Step for $name {
 335             type Output = PathBuf;
 336
 337             fn should_run(run: ShouldRun) -> ShouldRun {
 338                 run.path($path)
 339             }
 340
 341             fn make_run(run: RunConfig) {
 342                 run.builder.ensure($name {
 343                     compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 344                     target: run.target,
 345                 });
 346             }
 347
 348             fn run(self, builder: &Builder) -> PathBuf {
 349                 builder.ensure(ToolBuild {
 350                     compiler: self.compiler,
 351                     target: self.target,
 352                     tool: $tool_name,
 353                     mode: $mode,
 354                     path: $path,
 355                     is_optional_tool: false,
 356                     source_type: if false $(|| $external)* {
 357                         SourceType::Submodule
 358                     } else {
 359                         SourceType::InTree
 360                     },
 361                     extra_features: Vec::new(),
 362                 }).expect("expected to build -- essential tool")
 363             }
 364         }
 365         )+
 366     }
 367 }
 368
 369 tool!(
 370     Rustbook, "src/tools/rustbook", "rustbook", Mode::ToolBootstrap;
 371     ErrorIndex, "src/tools/error_index_generator", "error_index_generator", Mode::ToolRustc;
 372     UnstableBookGen, "src/tools/unstable-book-gen", "unstable-book-gen", Mode::ToolBootstrap;
 373     Tidy, "src/tools/tidy", "tidy", Mode::ToolBootstrap;
 374     Linkchecker, "src/tools/linkchecker", "linkchecker", Mode::ToolBootstrap;
 375     CargoTest, "src/tools/cargotest", "cargotest", Mode::ToolBootstrap, cargo_test_root = true;
 376     Compiletest, "src/tools/compiletest", "compiletest", Mode::ToolBootstrap,
 377         llvm_tools = true, cargo_test_root = true;
 378     BuildManifest, "src/tools/build-manifest", "build-manifest", Mode::ToolBootstrap;
 379     RemoteTestClient, "src/tools/remote-test-client", "remote-test-client", Mode::ToolBootstrap;
 380     RustInstaller, "src/tools/rust-installer", "fabricate", Mode::ToolBootstrap,
 381         is_external_tool = true;
 382     RustdocTheme, "src/tools/rustdoc-themes", "rustdoc-themes", Mode::ToolBootstrap;
 383 );
 384
 385 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 386 pub struct RemoteTestServer {
 387     pub compiler: Compiler,
 388     pub target: Interned<String>,
 389 }
 390
 391 impl Step for RemoteTestServer {
 392     type Output = PathBuf;
 393
 394     fn should_run(run: ShouldRun) -> ShouldRun {
 395         run.path("src/tools/remote-test-server")
 396     }
 397
 398     fn make_run(run: RunConfig) {
 399         run.builder.ensure(RemoteTestServer {
 400             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 401             target: run.target,
 402         });
 403     }
 404
 405     fn run(self, builder: &Builder) -> PathBuf {
 406         builder.ensure(ToolBuild {
 407             compiler: self.compiler,
 408             target: self.target,
 409             tool: "remote-test-server",
 410             mode: Mode::ToolStd,
 411             path: "src/tools/remote-test-server",
 412             is_optional_tool: false,
 413             source_type: SourceType::InTree,
 414             extra_features: Vec::new(),
 415         }).expect("expected to build -- essential tool")
 416     }
 417 }
 418
 419 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 420 pub struct Rustdoc {
 421     pub host: Interned<String>,
 422 }
 423
 424 impl Step for Rustdoc {
 425     type Output = PathBuf;
 426     const DEFAULT: bool = true;
 427     const ONLY_HOSTS: bool = true;
 428
 429     fn should_run(run: ShouldRun) -> ShouldRun {
 430         run.path("src/tools/rustdoc")
 431     }
 432
 433     fn make_run(run: RunConfig) {
 434         run.builder.ensure(Rustdoc {
 435             host: run.host,
 436         });
 437     }
 438
 439     fn run(self, builder: &Builder) -> PathBuf {
 440         let target_compiler = builder.compiler(builder.top_stage, self.host);
 441         let target = target_compiler.host;
 442         let build_compiler = if target_compiler.stage == 0 {
 443             builder.compiler(0, builder.config.build)
 444         } else if target_compiler.stage >= 2 {
 445             // Past stage 2, we consider the compiler to be ABI-compatible and hence capable of
 446             // building rustdoc itself.
 447             builder.compiler(target_compiler.stage, builder.config.build)
 448         } else {
 449             // Similar to `compile::Assemble`, build with the previous stage's compiler. Otherwise
 450             // we'd have stageN/bin/rustc and stageN/bin/rustdoc be effectively different stage
 451             // compilers, which isn't what we want.
 452             builder.compiler(target_compiler.stage - 1, builder.config.build)
 453         };
 454
 455         builder.ensure(compile::Rustc { compiler: build_compiler, target });
 456         builder.ensure(compile::Rustc {
 457             compiler: build_compiler,
 458             target: builder.config.build,
 459         });
 460
 461         let mut cargo = prepare_tool_cargo(
 462             builder,
 463             build_compiler,
 464             Mode::ToolRustc,
 465             target,
 466             "build",
 467             "src/tools/rustdoc",
 468             SourceType::InTree,
 469             &[],
 470         );
 471
 472         // Most tools don't get debuginfo, but rustdoc should.
 473         cargo.env("RUSTC_DEBUGINFO", builder.config.rust_debuginfo.to_string())
 474              .env("RUSTC_DEBUGINFO_LINES", builder.config.rust_debuginfo_lines.to_string());
 475
 476         let _folder = builder.fold_output(|| format!("stage{}-rustdoc", target_compiler.stage));
 477         builder.info(&format!("Building rustdoc for stage{} ({})",
 478             target_compiler.stage, target_compiler.host));
 479         builder.run(&mut cargo);
 480
 481         // Cargo adds a number of paths to the dylib search path on windows, which results in
 482         // the wrong rustdoc being executed. To avoid the conflicting rustdocs, we name the "tool"
 483         // rustdoc a different name.
 484         let tool_rustdoc = builder.cargo_out(build_compiler, Mode::ToolRustc, target)
 485             .join(exe("rustdoc_tool_binary", &target_compiler.host));
 486
 487         // don't create a stage0-sysroot/bin directory.
 488         if target_compiler.stage > 0 {
 489             let sysroot = builder.sysroot(target_compiler);
 490             let bindir = sysroot.join("bin");
 491             t!(fs::create_dir_all(&bindir));
 492             let bin_rustdoc = bindir.join(exe("rustdoc", &*target_compiler.host));
 493             let _ = fs::remove_file(&bin_rustdoc);
 494             builder.copy(&tool_rustdoc, &bin_rustdoc);
 495             bin_rustdoc
 496         } else {
 497             tool_rustdoc
 498         }
 499     }
 500 }
 501
 502 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 503 pub struct Cargo {
 504     pub compiler: Compiler,
 505     pub target: Interned<String>,
 506 }
 507
 508 impl Step for Cargo {
 509     type Output = PathBuf;
 510     const DEFAULT: bool = true;
 511     const ONLY_HOSTS: bool = true;
 512
 513     fn should_run(run: ShouldRun) -> ShouldRun {
 514         let builder = run.builder;
 515         run.path("src/tools/cargo").default_condition(builder.config.extended)
 516     }
 517
 518     fn make_run(run: RunConfig) {
 519         run.builder.ensure(Cargo {
 520             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 521             target: run.target,
 522         });
 523     }
 524
 525     fn run(self, builder: &Builder) -> PathBuf {
 526         // Cargo depends on procedural macros, which requires a full host
 527         // compiler to be available, so we need to depend on that.
 528         builder.ensure(compile::Rustc {
 529             compiler: self.compiler,
 530             target: builder.config.build,
 531         });
 532         builder.ensure(ToolBuild {
 533             compiler: self.compiler,
 534             target: self.target,
 535             tool: "cargo",
 536             mode: Mode::ToolRustc,
 537             path: "src/tools/cargo",
 538             is_optional_tool: false,
 539             source_type: SourceType::Submodule,
 540             extra_features: Vec::new(),
 541         }).expect("expected to build -- essential tool")
 542     }
 543 }
 544
 545 macro_rules! tool_extended {
 546     (($sel:ident, $builder:ident),
 547        $($name:ident,
 548        $toolstate:ident,
 549        $path:expr,
 550        $tool_name:expr,
 551        $extra_deps:block;)+) => {
 552         $(
 553             #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 554         pub struct $name {
 555             pub compiler: Compiler,
 556             pub target: Interned<String>,
 557             pub extra_features: Vec<String>,
 558         }
 559
 560         impl Step for $name {
 561             type Output = Option<PathBuf>;
 562             const DEFAULT: bool = true;
 563             const ONLY_HOSTS: bool = true;
 564
 565             fn should_run(run: ShouldRun) -> ShouldRun {
 566                 let builder = run.builder;
 567                 run.path($path).default_condition(builder.config.extended)
 568             }
 569
 570             fn make_run(run: RunConfig) {
 571                 run.builder.ensure($name {
 572                     compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 573                     target: run.target,
 574                     extra_features: Vec::new(),
 575                 });
 576             }
 577
 578             #[allow(unused_mut)]
 579             fn run(mut $sel, $builder: &Builder) -> Option<PathBuf> {
 580                 $extra_deps
 581                 $builder.ensure(ToolBuild {
 582                     compiler: $sel.compiler,
 583                     target: $sel.target,
 584                     tool: $tool_name,
 585                     mode: Mode::ToolRustc,
 586                     path: $path,
 587                     extra_features: $sel.extra_features,
 588                     is_optional_tool: true,
 589                     source_type: SourceType::Submodule,
 590                 })
 591             }
 592         }
 593         )+
 594     }
 595 }
 596
 597 tool_extended!((self, builder),
 598     Cargofmt, rustfmt, "src/tools/rustfmt", "cargo-fmt", {};
 599     CargoClippy, clippy, "src/tools/clippy", "cargo-clippy", {
 600         // Clippy depends on procedural macros (serde), which requires a full host
 601         // compiler to be available, so we need to depend on that.
 602         builder.ensure(compile::Rustc {
 603             compiler: self.compiler,
 604             target: builder.config.build,
 605         });
 606     };
 607     Clippy, clippy, "src/tools/clippy", "clippy-driver", {
 608         // Clippy depends on procedural macros (serde), which requires a full host
 609         // compiler to be available, so we need to depend on that.
 610         builder.ensure(compile::Rustc {
 611             compiler: self.compiler,
 612             target: builder.config.build,
 613         });
 614     };
 615     Miri, miri, "src/tools/miri", "miri", {};
 616     Rls, rls, "src/tools/rls", "rls", {
 617         let clippy = builder.ensure(Clippy {
 618             compiler: self.compiler,
 619             target: self.target,
 620             extra_features: Vec::new(),
 621         });
 622         if clippy.is_some() {
 623             self.extra_features.push("clippy".to_owned());
 624         }
 625         // RLS depends on procedural macros, which requires a full host
 626         // compiler to be available, so we need to depend on that.
 627         builder.ensure(compile::Rustc {
 628             compiler: self.compiler,
 629             target: builder.config.build,
 630         });
 631     };
 632     Rustfmt, rustfmt, "src/tools/rustfmt", "rustfmt", {};
 633 );
 634
 635 impl<'a> Builder<'a> {
 636     /// Get a `Command` which is ready to run `tool` in `stage` built for
 637     /// `host`.
 638     pub fn tool_cmd(&self, tool: Tool) -> Command {
 639         let mut cmd = Command::new(self.tool_exe(tool));
 640         let compiler = self.compiler(self.tool_default_stage(tool), self.config.build);
 641         self.prepare_tool_cmd(compiler, tool, &mut cmd);
 642         cmd
 643     }
 644
 645     /// Prepares the `cmd` provided to be able to run the `compiler` provided.
 646     ///
 647     /// Notably this munges the dynamic library lookup path to point to the
 648     /// right location to run `compiler`.
 649     fn prepare_tool_cmd(&self, compiler: Compiler, tool: Tool, cmd: &mut Command) {
 650         let host = &compiler.host;
 651         let mut lib_paths: Vec<PathBuf> = vec![
 652             if compiler.stage == 0 && tool != Tool::ErrorIndex {
 653                 self.build.rustc_snapshot_libdir()
 654             } else {
 655                 PathBuf::from(&self.sysroot_libdir(compiler, compiler.host))
 656             },
 657             self.cargo_out(compiler, tool.get_mode(), *host).join("deps"),
 658         ];
 659
 660         // On MSVC a tool may invoke a C compiler (e.g. compiletest in run-make
 661         // mode) and that C compiler may need some extra PATH modification. Do
 662         // so here.
 663         if compiler.host.contains("msvc") {
 664             let curpaths = env::var_os("PATH").unwrap_or_default();
 665             let curpaths = env::split_paths(&curpaths).collect::<Vec<_>>();
 666             for &(ref k, ref v) in self.cc[&compiler.host].env() {
 667                 if k != "PATH" {
 668                     continue
 669                 }
 670                 for path in env::split_paths(v) {
 671                     if !curpaths.contains(&path) {
 672                         lib_paths.push(path);
 673                     }
 674                 }
 675             }
 676         }
 677
 678         // Add the llvm/bin directory to PATH since it contains lots of
 679         // useful, platform-independent tools
 680         if tool.uses_llvm_tools() {
 681             if let Some(llvm_bin_path) = self.llvm_bin_path() {
 682                 if host.contains("windows") {
 683                     // On Windows, PATH and the dynamic library path are the same,
 684                     // so we just add the LLVM bin path to lib_path
 685                     lib_paths.push(llvm_bin_path);
 686                 } else {
 687                     let old_path = env::var_os("PATH").unwrap_or_default();
 688                     let new_path = env::join_paths(iter::once(llvm_bin_path)
 689                             .chain(env::split_paths(&old_path)))
 690                         .expect("Could not add LLVM bin path to PATH");
 691                     cmd.env("PATH", new_path);
 692                 }
 693             }
 694         }
 695
 696         // Set `__CARGO_TEST_ROOT` to the build directory if needed.
 697         if tool.needs_cargo_test_root() {
 698             cmd.env("__CARGO_TEST_ROOT", &self.config.out);
 699         }
 700
 701         add_lib_path(lib_paths, cmd);
 702     }
 703
 704     fn llvm_bin_path(&self) -> Option<PathBuf> {
 705         if self.config.llvm_enabled && !self.config.dry_run {
 706             let llvm_config = self.ensure(native::Llvm {
 707                 target: self.config.build,
 708                 emscripten: false,
 709             });
 710
 711             // Add the llvm/bin directory to PATH since it contains lots of
 712             // useful, platform-independent tools
 713             let llvm_bin_path = llvm_config.parent()
 714                 .expect("Expected llvm-config to be contained in directory");
 715             assert!(llvm_bin_path.is_dir());
 716             Some(llvm_bin_path.to_path_buf())
 717         } else {
 718             None
 719         }
 720     }
 721 }