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
  17 use Mode;
  18 use Compiler;
  19 use builder::{Step, RunConfig, ShouldRun, Builder};
  20 use util::{exe, add_lib_path};
  21 use compile::{self, libtest_stamp, libstd_stamp, librustc_stamp};
  22 use native;
  23 use channel::GitInfo;
  24 use cache::Interned;
  25 use toolstate::ToolState;
  26
  27 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
  28 pub struct CleanTools {
  29     pub compiler: Compiler,
  30     pub target: Interned<String>,
  31     pub cause: Mode,
  32 }
  33
  34 impl Step for CleanTools {
  35     type Output = ();
  36
  37     fn should_run(run: ShouldRun) -> ShouldRun {
  38         run.never()
  39     }
  40
  41     fn run(self, builder: &Builder) {
  42         let compiler = self.compiler;
  43         let target = self.target;
  44         let cause = self.cause;
  45
  46         // This is for the original compiler, but if we're forced to use stage 1, then
  47         // std/test/rustc stamps won't exist in stage 2, so we need to get those from stage 1, since
  48         // we copy the libs forward.
  49         let tools_dir = builder.stage_out(compiler, Mode::ToolRustc);
  50         let compiler = if builder.force_use_stage1(compiler, target) {
  51             builder.compiler(1, compiler.host)
  52         } else {
  53             compiler
  54         };
  55
  56         for &cur_mode in &[Mode::Std, Mode::Test, Mode::Rustc] {
  57             let stamp = match cur_mode {
  58                 Mode::Std => libstd_stamp(builder, compiler, target),
  59                 Mode::Test => libtest_stamp(builder, compiler, target),
  60                 Mode::Rustc => librustc_stamp(builder, compiler, target),
  61                 _ => panic!(),
  62             };
  63
  64             if builder.clear_if_dirty(&tools_dir, &stamp) {
  65                 break;
  66             }
  67
  68             // If we are a rustc tool, and std changed, we also need to clear ourselves out -- our
  69             // dependencies depend on std. Therefore, we iterate up until our own mode.
  70             if cause == cur_mode {
  71                 break;
  72             }
  73         }
  74     }
  75 }
  76
  77 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
  78 struct ToolBuild {
  79     compiler: Compiler,
  80     target: Interned<String>,
  81     tool: &'static str,
  82     path: &'static str,
  83     mode: Mode,
  84     is_ext_tool: bool,
  85     extra_features: Vec<String>,
  86 }
  87
  88 impl Step for ToolBuild {
  89     type Output = Option<PathBuf>;
  90
  91     fn should_run(run: ShouldRun) -> ShouldRun {
  92         run.never()
  93     }
  94
  95     /// Build a tool in `src/tools`
  96     ///
  97     /// This will build the specified tool with the specified `host` compiler in
  98     /// `stage` into the normal cargo output directory.
  99     fn run(self, builder: &Builder) -> Option<PathBuf> {
 100         let compiler = self.compiler;
 101         let target = self.target;
 102         let tool = self.tool;
 103         let path = self.path;
 104         let is_ext_tool = self.is_ext_tool;
 105
 106         match self.mode {
 107             Mode::ToolStd => builder.ensure(compile::Std { compiler, target }),
 108             Mode::ToolTest => builder.ensure(compile::Test { compiler, target }),
 109             Mode::ToolRustc => builder.ensure(compile::Rustc { compiler, target }),
 110             _ => panic!("unexpected Mode for tool build")
 111         }
 112
 113         let mut cargo = prepare_tool_cargo(builder, compiler, self.mode, target, "build", path);
 114         cargo.arg("--features").arg(self.extra_features.join(" "));
 115
 116         let _folder = builder.fold_output(|| format!("stage{}-{}", compiler.stage, tool));
 117         builder.info(&format!("Building stage{} tool {} ({})", compiler.stage, tool, target));
 118         let mut duplicates = Vec::new();
 119         let is_expected = compile::stream_cargo(builder, &mut cargo, &mut |msg| {
 120             // Only care about big things like the RLS/Cargo for now
 121             match tool {
 122                 | "rls"
 123                 | "cargo"
 124                 | "clippy-driver"
 125                 => {}
 126
 127                 _ => return,
 128             }
 129             let (id, features, filenames) = match msg {
 130                 compile::CargoMessage::CompilerArtifact {
 131                     package_id,
 132                     features,
 133                     filenames
 134                 } => {
 135                     (package_id, features, filenames)
 136                 }
 137                 _ => return,
 138             };
 139             let features = features.iter().map(|s| s.to_string()).collect::<Vec<_>>();
 140
 141             for path in filenames {
 142                 let val = (tool, PathBuf::from(&*path), features.clone());
 143                 // we're only interested in deduplicating rlibs for now
 144                 if val.1.extension().and_then(|s| s.to_str()) != Some("rlib") {
 145                     continue
 146                 }
 147
 148                 // Don't worry about libs that turn out to be host dependencies
 149                 // or build scripts, we only care about target dependencies that
 150                 // are in `deps`.
 151                 if let Some(maybe_target) = val.1
 152                     .parent()                   // chop off file name
 153                     .and_then(|p| p.parent())   // chop off `deps`
 154                     .and_then(|p| p.parent())   // chop off `release`
 155                     .and_then(|p| p.file_name())
 156                     .and_then(|p| p.to_str())
 157                 {
 158                     if maybe_target != &*target {
 159                         continue
 160                     }
 161                 }
 162
 163                 let mut artifacts = builder.tool_artifacts.borrow_mut();
 164                 let prev_artifacts = artifacts
 165                     .entry(target)
 166                     .or_insert_with(Default::default);
 167                 if let Some(prev) = prev_artifacts.get(&*id) {
 168                     if prev.1 != val.1 {
 169                         duplicates.push((
 170                             id.to_string(),
 171                             val,
 172                             prev.clone(),
 173                         ));
 174                     }
 175                     return
 176                 }
 177                 prev_artifacts.insert(id.to_string(), val);
 178             }
 179         });
 180
 181         if is_expected && duplicates.len() != 0 {
 182             println!("duplicate artfacts found when compiling a tool, this \
 183                       typically means that something was recompiled because \
 184                       a transitive dependency has different features activated \
 185                       than in a previous build:\n");
 186             for (id, cur, prev) in duplicates {
 187                 println!("  {}", id);
 188                 println!("    `{}` enabled features {:?} at {:?}",
 189                          cur.0, cur.2, cur.1);
 190                 println!("    `{}` enabled features {:?} at {:?}",
 191                          prev.0, prev.2, prev.1);
 192             }
 193             println!("");
 194             panic!("tools should not compile multiple copies of the same crate");
 195         }
 196
 197         builder.save_toolstate(tool, if is_expected {
 198             ToolState::TestFail
 199         } else {
 200             ToolState::BuildFail
 201         });
 202
 203         if !is_expected {
 204             if !is_ext_tool {
 205                 exit(1);
 206             } else {
 207                 return None;
 208             }
 209         } else {
 210             let cargo_out = builder.cargo_out(compiler, self.mode, target)
 211                 .join(exe(tool, &compiler.host));
 212             let bin = builder.tools_dir(compiler).join(exe(tool, &compiler.host));
 213             builder.copy(&cargo_out, &bin);
 214             Some(bin)
 215         }
 216     }
 217 }
 218
 219 pub fn prepare_tool_cargo(
 220     builder: &Builder,
 221     compiler: Compiler,
 222     mode: Mode,
 223     target: Interned<String>,
 224     command: &'static str,
 225     path: &'static str,
 226 ) -> Command {
 227     let mut cargo = builder.cargo(compiler, mode, target, command);
 228     let dir = builder.src.join(path);
 229     cargo.arg("--manifest-path").arg(dir.join("Cargo.toml"));
 230
 231     // We don't want to build tools dynamically as they'll be running across
 232     // stages and such and it's just easier if they're not dynamically linked.
 233     cargo.env("RUSTC_NO_PREFER_DYNAMIC", "1");
 234
 235     if let Some(dir) = builder.openssl_install_dir(target) {
 236         cargo.env("OPENSSL_STATIC", "1");
 237         cargo.env("OPENSSL_DIR", dir);
 238         cargo.env("LIBZ_SYS_STATIC", "1");
 239     }
 240
 241     // if tools are using lzma we want to force the build script to build its
 242     // own copy
 243     cargo.env("LZMA_API_STATIC", "1");
 244
 245     cargo.env("CFG_RELEASE_CHANNEL", &builder.config.channel);
 246     cargo.env("CFG_VERSION", builder.rust_version());
 247
 248     let info = GitInfo::new(&builder.config, &dir);
 249     if let Some(sha) = info.sha() {
 250         cargo.env("CFG_COMMIT_HASH", sha);
 251     }
 252     if let Some(sha_short) = info.sha_short() {
 253         cargo.env("CFG_SHORT_COMMIT_HASH", sha_short);
 254     }
 255     if let Some(date) = info.commit_date() {
 256         cargo.env("CFG_COMMIT_DATE", date);
 257     }
 258     cargo
 259 }
 260
 261 macro_rules! tool {
 262     ($($name:ident, $path:expr, $tool_name:expr, $mode:expr $(,llvm_tools = $llvm:expr)*;)+) => {
 263         #[derive(Copy, 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_ext_tool: false,
 340                     extra_features: Vec::new(),
 341                 }).expect("expected to build -- essential tool")
 342             }
 343         }
 344         )+
 345     }
 346 }
 347
 348 tool!(
 349     Rustbook, "src/tools/rustbook", "rustbook", Mode::ToolRustc;
 350     ErrorIndex, "src/tools/error_index_generator", "error_index_generator", Mode::ToolRustc;
 351     UnstableBookGen, "src/tools/unstable-book-gen", "unstable-book-gen", Mode::ToolStd;
 352     Tidy, "src/tools/tidy", "tidy", Mode::ToolStd;
 353     Linkchecker, "src/tools/linkchecker", "linkchecker", Mode::ToolStd;
 354     CargoTest, "src/tools/cargotest", "cargotest", Mode::ToolStd;
 355     Compiletest, "src/tools/compiletest", "compiletest", Mode::ToolTest, llvm_tools = true;
 356     BuildManifest, "src/tools/build-manifest", "build-manifest", Mode::ToolStd;
 357     RemoteTestClient, "src/tools/remote-test-client", "remote-test-client", Mode::ToolStd;
 358     RustInstaller, "src/tools/rust-installer", "fabricate", Mode::ToolStd;
 359     RustdocTheme, "src/tools/rustdoc-themes", "rustdoc-themes", Mode::ToolStd;
 360 );
 361
 362 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 363 pub struct RemoteTestServer {
 364     pub compiler: Compiler,
 365     pub target: Interned<String>,
 366 }
 367
 368 impl Step for RemoteTestServer {
 369     type Output = PathBuf;
 370
 371     fn should_run(run: ShouldRun) -> ShouldRun {
 372         run.path("src/tools/remote-test-server")
 373     }
 374
 375     fn make_run(run: RunConfig) {
 376         run.builder.ensure(RemoteTestServer {
 377             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 378             target: run.target,
 379         });
 380     }
 381
 382     fn run(self, builder: &Builder) -> PathBuf {
 383         builder.ensure(ToolBuild {
 384             compiler: self.compiler,
 385             target: self.target,
 386             tool: "remote-test-server",
 387             mode: Mode::ToolStd,
 388             path: "src/tools/remote-test-server",
 389             is_ext_tool: false,
 390             extra_features: Vec::new(),
 391         }).expect("expected to build -- essential tool")
 392     }
 393 }
 394
 395 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 396 pub struct Rustdoc {
 397     pub host: Interned<String>,
 398 }
 399
 400 impl Step for Rustdoc {
 401     type Output = PathBuf;
 402     const DEFAULT: bool = true;
 403     const ONLY_HOSTS: bool = true;
 404
 405     fn should_run(run: ShouldRun) -> ShouldRun {
 406         run.path("src/tools/rustdoc")
 407     }
 408
 409     fn make_run(run: RunConfig) {
 410         run.builder.ensure(Rustdoc {
 411             host: run.host,
 412         });
 413     }
 414
 415     fn run(self, builder: &Builder) -> PathBuf {
 416         let target_compiler = builder.compiler(builder.top_stage, self.host);
 417         let target = target_compiler.host;
 418         let build_compiler = if target_compiler.stage == 0 {
 419             builder.compiler(0, builder.config.build)
 420         } else if target_compiler.stage >= 2 {
 421             // Past stage 2, we consider the compiler to be ABI-compatible and hence capable of
 422             // building rustdoc itself.
 423             builder.compiler(target_compiler.stage, builder.config.build)
 424         } else {
 425             // Similar to `compile::Assemble`, build with the previous stage's compiler. Otherwise
 426             // we'd have stageN/bin/rustc and stageN/bin/rustdoc be effectively different stage
 427             // compilers, which isn't what we want.
 428             builder.compiler(target_compiler.stage - 1, builder.config.build)
 429         };
 430
 431         builder.ensure(compile::Rustc { compiler: build_compiler, target });
 432         builder.ensure(compile::Rustc {
 433             compiler: build_compiler,
 434             target: builder.config.build,
 435         });
 436
 437         let mut cargo = prepare_tool_cargo(builder,
 438                                            build_compiler,
 439                                            Mode::ToolRustc,
 440                                            target,
 441                                            "build",
 442                                            "src/tools/rustdoc");
 443
 444         // Most tools don't get debuginfo, but rustdoc should.
 445         cargo.env("RUSTC_DEBUGINFO", builder.config.rust_debuginfo.to_string())
 446              .env("RUSTC_DEBUGINFO_LINES", builder.config.rust_debuginfo_lines.to_string());
 447
 448         let _folder = builder.fold_output(|| format!("stage{}-rustdoc", target_compiler.stage));
 449         builder.info(&format!("Building rustdoc for stage{} ({})",
 450             target_compiler.stage, target_compiler.host));
 451         builder.run(&mut cargo);
 452
 453         // Cargo adds a number of paths to the dylib search path on windows, which results in
 454         // the wrong rustdoc being executed. To avoid the conflicting rustdocs, we name the "tool"
 455         // rustdoc a different name.
 456         let tool_rustdoc = builder.cargo_out(build_compiler, Mode::ToolRustc, target)
 457             .join(exe("rustdoc_tool_binary", &target_compiler.host));
 458
 459         // don't create a stage0-sysroot/bin directory.
 460         if target_compiler.stage > 0 {
 461             let sysroot = builder.sysroot(target_compiler);
 462             let bindir = sysroot.join("bin");
 463             t!(fs::create_dir_all(&bindir));
 464             let bin_rustdoc = bindir.join(exe("rustdoc", &*target_compiler.host));
 465             let _ = fs::remove_file(&bin_rustdoc);
 466             builder.copy(&tool_rustdoc, &bin_rustdoc);
 467             bin_rustdoc
 468         } else {
 469             tool_rustdoc
 470         }
 471     }
 472 }
 473
 474 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 475 pub struct Cargo {
 476     pub compiler: Compiler,
 477     pub target: Interned<String>,
 478 }
 479
 480 impl Step for Cargo {
 481     type Output = PathBuf;
 482     const DEFAULT: bool = true;
 483     const ONLY_HOSTS: bool = true;
 484
 485     fn should_run(run: ShouldRun) -> ShouldRun {
 486         let builder = run.builder;
 487         run.path("src/tools/cargo").default_condition(builder.config.extended)
 488     }
 489
 490     fn make_run(run: RunConfig) {
 491         run.builder.ensure(Cargo {
 492             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 493             target: run.target,
 494         });
 495     }
 496
 497     fn run(self, builder: &Builder) -> PathBuf {
 498         builder.ensure(native::Openssl {
 499             target: self.target,
 500         });
 501         // Cargo depends on procedural macros, which requires a full host
 502         // compiler to be available, so we need to depend on that.
 503         builder.ensure(compile::Rustc {
 504             compiler: self.compiler,
 505             target: builder.config.build,
 506         });
 507         builder.ensure(ToolBuild {
 508             compiler: self.compiler,
 509             target: self.target,
 510             tool: "cargo",
 511             mode: Mode::ToolRustc,
 512             path: "src/tools/cargo",
 513             is_ext_tool: false,
 514             extra_features: Vec::new(),
 515         }).expect("expected to build -- essential tool")
 516     }
 517 }
 518
 519 macro_rules! tool_extended {
 520     (($sel:ident, $builder:ident),
 521        $($name:ident,
 522        $toolstate:ident,
 523        $path:expr,
 524        $tool_name:expr,
 525        $extra_deps:block;)+) => {
 526         $(
 527             #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 528         pub struct $name {
 529             pub compiler: Compiler,
 530             pub target: Interned<String>,
 531             pub extra_features: Vec<String>,
 532         }
 533
 534         impl Step for $name {
 535             type Output = Option<PathBuf>;
 536             const DEFAULT: bool = true;
 537             const ONLY_HOSTS: bool = true;
 538
 539             fn should_run(run: ShouldRun) -> ShouldRun {
 540                 let builder = run.builder;
 541                 run.path($path).default_condition(builder.config.extended)
 542             }
 543
 544             fn make_run(run: RunConfig) {
 545                 run.builder.ensure($name {
 546                     compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 547                     target: run.target,
 548                     extra_features: Vec::new(),
 549                 });
 550             }
 551
 552             #[allow(unused_mut)]
 553             fn run(mut $sel, $builder: &Builder) -> Option<PathBuf> {
 554                 $extra_deps
 555                 $builder.ensure(ToolBuild {
 556                     compiler: $sel.compiler,
 557                     target: $sel.target,
 558                     tool: $tool_name,
 559                     mode: Mode::ToolRustc,
 560                     path: $path,
 561                     extra_features: $sel.extra_features,
 562                     is_ext_tool: true,
 563                 })
 564             }
 565         }
 566         )+
 567     }
 568 }
 569
 570 tool_extended!((self, builder),
 571     Cargofmt, rustfmt, "src/tools/rustfmt", "cargo-fmt", {};
 572     Clippy, clippy, "src/tools/clippy", "clippy-driver", {
 573         // Clippy depends on procedural macros (serde), which requires a full host
 574         // compiler to be available, so we need to depend on that.
 575         builder.ensure(compile::Rustc {
 576             compiler: self.compiler,
 577             target: builder.config.build,
 578         });
 579     };
 580     Miri, miri, "src/tools/miri", "miri", {};
 581     Rls, rls, "src/tools/rls", "rls", {
 582         builder.ensure(native::Openssl {
 583             target: self.target,
 584         });
 585         // RLS depends on procedural macros, which requires a full host
 586         // compiler to be available, so we need to depend on that.
 587         builder.ensure(compile::Rustc {
 588             compiler: self.compiler,
 589             target: builder.config.build,
 590         });
 591     };
 592     Rustfmt, rustfmt, "src/tools/rustfmt", "rustfmt", {};
 593 );
 594
 595 impl<'a> Builder<'a> {
 596     /// Get a `Command` which is ready to run `tool` in `stage` built for
 597     /// `host`.
 598     pub fn tool_cmd(&self, tool: Tool) -> Command {
 599         let mut cmd = Command::new(self.tool_exe(tool));
 600         let compiler = self.compiler(self.tool_default_stage(tool), self.config.build);
 601         self.prepare_tool_cmd(compiler, tool, &mut cmd);
 602         cmd
 603     }
 604
 605     /// Prepares the `cmd` provided to be able to run the `compiler` provided.
 606     ///
 607     /// Notably this munges the dynamic library lookup path to point to the
 608     /// right location to run `compiler`.
 609     fn prepare_tool_cmd(&self, compiler: Compiler, tool: Tool, cmd: &mut Command) {
 610         let host = &compiler.host;
 611         let mut lib_paths: Vec<PathBuf> = vec![
 612             PathBuf::from(&self.sysroot_libdir(compiler, compiler.host)),
 613             self.cargo_out(compiler, tool.get_mode(), *host).join("deps"),
 614         ];
 615
 616         // On MSVC a tool may invoke a C compiler (e.g. compiletest in run-make
 617         // mode) and that C compiler may need some extra PATH modification. Do
 618         // so here.
 619         if compiler.host.contains("msvc") {
 620             let curpaths = env::var_os("PATH").unwrap_or_default();
 621             let curpaths = env::split_paths(&curpaths).collect::<Vec<_>>();
 622             for &(ref k, ref v) in self.cc[&compiler.host].env() {
 623                 if k != "PATH" {
 624                     continue
 625                 }
 626                 for path in env::split_paths(v) {
 627                     if !curpaths.contains(&path) {
 628                         lib_paths.push(path);
 629                     }
 630                 }
 631             }
 632         }
 633
 634         // Add the llvm/bin directory to PATH since it contains lots of
 635         // useful, platform-independent tools
 636         if tool.uses_llvm_tools() {
 637             if let Some(llvm_bin_path) = self.llvm_bin_path() {
 638                 if host.contains("windows") {
 639                     // On Windows, PATH and the dynamic library path are the same,
 640                     // so we just add the LLVM bin path to lib_path
 641                     lib_paths.push(llvm_bin_path);
 642                 } else {
 643                     let old_path = env::var_os("PATH").unwrap_or_default();
 644                     let new_path = env::join_paths(iter::once(llvm_bin_path)
 645                             .chain(env::split_paths(&old_path)))
 646                         .expect("Could not add LLVM bin path to PATH");
 647                     cmd.env("PATH", new_path);
 648                 }
 649             }
 650         }
 651
 652         add_lib_path(lib_paths, cmd);
 653     }
 654
 655     fn llvm_bin_path(&self) -> Option<PathBuf> {
 656         if self.config.llvm_enabled && !self.config.dry_run {
 657             let llvm_config = self.ensure(native::Llvm {
 658                 target: self.config.build,
 659                 emscripten: false,
 660             });
 661
 662             // Add the llvm/bin directory to PATH since it contains lots of
 663             // useful, platform-independent tools
 664             let llvm_bin_path = llvm_config.parent()
 665                 .expect("Expected llvm-config to be contained in directory");
 666             assert!(llvm_bin_path.is_dir());
 667             Some(llvm_bin_path.to_path_buf())
 668         } else {
 669             None
 670         }
 671     }
 672 }