src/bootstrap/tool.rs

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