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