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         ;
 268     )+) => {
 269         #[derive(Copy, PartialEq, Eq, Clone)]
 270         pub enum Tool {
 271             $(
 272                 $name,
 273             )+
 274         }
 275
 276         impl Tool {
 277             pub fn get_mode(&self) -> Mode {
 278                 let mode = match self {
 279                     $(Tool::$name => $mode,)+
 280                 };
 281                 mode
 282             }
 283
 284             /// Whether this tool requires LLVM to run
 285             pub fn uses_llvm_tools(&self) -> bool {
 286                 match self {
 287                     $(Tool::$name => false $(|| $llvm)*,)+
 288                 }
 289             }
 290         }
 291
 292         impl<'a> Builder<'a> {
 293             pub fn tool_exe(&self, tool: Tool) -> PathBuf {
 294                 let stage = self.tool_default_stage(tool);
 295                 match tool {
 296                     $(Tool::$name =>
 297                         self.ensure($name {
 298                             compiler: self.compiler(stage, self.config.build),
 299                             target: self.config.build,
 300                         }),
 301                     )+
 302                 }
 303             }
 304
 305             pub fn tool_default_stage(&self, tool: Tool) -> u32 {
 306                 // Compile the error-index in the same stage as rustdoc to avoid
 307                 // recompiling rustdoc twice if we can. Otherwise compile
 308                 // everything else in stage0 as there's no need to rebootstrap
 309                 // everything.
 310                 match tool {
 311                     Tool::ErrorIndex if self.top_stage >= 2 => self.top_stage,
 312                     _ => 0,
 313                 }
 314             }
 315         }
 316
 317         $(
 318             #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 319         pub struct $name {
 320             pub compiler: Compiler,
 321             pub target: Interned<String>,
 322         }
 323
 324         impl Step for $name {
 325             type Output = PathBuf;
 326
 327             fn should_run(run: ShouldRun) -> ShouldRun {
 328                 run.path($path)
 329             }
 330
 331             fn make_run(run: RunConfig) {
 332                 run.builder.ensure($name {
 333                     compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 334                     target: run.target,
 335                 });
 336             }
 337
 338             fn run(self, builder: &Builder) -> PathBuf {
 339                 builder.ensure(ToolBuild {
 340                     compiler: self.compiler,
 341                     target: self.target,
 342                     tool: $tool_name,
 343                     mode: $mode,
 344                     path: $path,
 345                     is_optional_tool: false,
 346                     source_type: if false $(|| $external)* {
 347                         SourceType::Submodule
 348                     } else {
 349                         SourceType::InTree
 350                     },
 351                     extra_features: Vec::new(),
 352                 }).expect("expected to build -- essential tool")
 353             }
 354         }
 355         )+
 356     }
 357 }
 358
 359 tool!(
 360     Rustbook, "src/tools/rustbook", "rustbook", Mode::ToolBootstrap;
 361     ErrorIndex, "src/tools/error_index_generator", "error_index_generator", Mode::ToolRustc;
 362     UnstableBookGen, "src/tools/unstable-book-gen", "unstable-book-gen", Mode::ToolBootstrap;
 363     Tidy, "src/tools/tidy", "tidy", Mode::ToolBootstrap;
 364     Linkchecker, "src/tools/linkchecker", "linkchecker", Mode::ToolBootstrap;
 365     CargoTest, "src/tools/cargotest", "cargotest", Mode::ToolBootstrap;
 366     Compiletest, "src/tools/compiletest", "compiletest", Mode::ToolBootstrap, llvm_tools = true;
 367     BuildManifest, "src/tools/build-manifest", "build-manifest", Mode::ToolBootstrap;
 368     RemoteTestClient, "src/tools/remote-test-client", "remote-test-client", Mode::ToolBootstrap;
 369     RustInstaller, "src/tools/rust-installer", "fabricate", Mode::ToolBootstrap,
 370         is_external_tool = true;
 371     RustdocTheme, "src/tools/rustdoc-themes", "rustdoc-themes", Mode::ToolBootstrap;
 372 );
 373
 374 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 375 pub struct RemoteTestServer {
 376     pub compiler: Compiler,
 377     pub target: Interned<String>,
 378 }
 379
 380 impl Step for RemoteTestServer {
 381     type Output = PathBuf;
 382
 383     fn should_run(run: ShouldRun) -> ShouldRun {
 384         run.path("src/tools/remote-test-server")
 385     }
 386
 387     fn make_run(run: RunConfig) {
 388         run.builder.ensure(RemoteTestServer {
 389             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 390             target: run.target,
 391         });
 392     }
 393
 394     fn run(self, builder: &Builder) -> PathBuf {
 395         builder.ensure(ToolBuild {
 396             compiler: self.compiler,
 397             target: self.target,
 398             tool: "remote-test-server",
 399             mode: Mode::ToolStd,
 400             path: "src/tools/remote-test-server",
 401             is_optional_tool: false,
 402             source_type: SourceType::InTree,
 403             extra_features: Vec::new(),
 404         }).expect("expected to build -- essential tool")
 405     }
 406 }
 407
 408 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 409 pub struct Rustdoc {
 410     pub host: Interned<String>,
 411 }
 412
 413 impl Step for Rustdoc {
 414     type Output = PathBuf;
 415     const DEFAULT: bool = true;
 416     const ONLY_HOSTS: bool = true;
 417
 418     fn should_run(run: ShouldRun) -> ShouldRun {
 419         run.path("src/tools/rustdoc")
 420     }
 421
 422     fn make_run(run: RunConfig) {
 423         run.builder.ensure(Rustdoc {
 424             host: run.host,
 425         });
 426     }
 427
 428     fn run(self, builder: &Builder) -> PathBuf {
 429         let target_compiler = builder.compiler(builder.top_stage, self.host);
 430         let target = target_compiler.host;
 431         let build_compiler = if target_compiler.stage == 0 {
 432             builder.compiler(0, builder.config.build)
 433         } else if target_compiler.stage >= 2 {
 434             // Past stage 2, we consider the compiler to be ABI-compatible and hence capable of
 435             // building rustdoc itself.
 436             builder.compiler(target_compiler.stage, builder.config.build)
 437         } else {
 438             // Similar to `compile::Assemble`, build with the previous stage's compiler. Otherwise
 439             // we'd have stageN/bin/rustc and stageN/bin/rustdoc be effectively different stage
 440             // compilers, which isn't what we want.
 441             builder.compiler(target_compiler.stage - 1, builder.config.build)
 442         };
 443
 444         builder.ensure(compile::Rustc { compiler: build_compiler, target });
 445         builder.ensure(compile::Rustc {
 446             compiler: build_compiler,
 447             target: builder.config.build,
 448         });
 449
 450         let mut cargo = prepare_tool_cargo(
 451             builder,
 452             build_compiler,
 453             Mode::ToolRustc,
 454             target,
 455             "build",
 456             "src/tools/rustdoc",
 457             SourceType::InTree,
 458             &[],
 459         );
 460
 461         // Most tools don't get debuginfo, but rustdoc should.
 462         cargo.env("RUSTC_DEBUGINFO", builder.config.rust_debuginfo.to_string())
 463              .env("RUSTC_DEBUGINFO_LINES", builder.config.rust_debuginfo_lines.to_string());
 464
 465         let _folder = builder.fold_output(|| format!("stage{}-rustdoc", target_compiler.stage));
 466         builder.info(&format!("Building rustdoc for stage{} ({})",
 467             target_compiler.stage, target_compiler.host));
 468         builder.run(&mut cargo);
 469
 470         // Cargo adds a number of paths to the dylib search path on windows, which results in
 471         // the wrong rustdoc being executed. To avoid the conflicting rustdocs, we name the "tool"
 472         // rustdoc a different name.
 473         let tool_rustdoc = builder.cargo_out(build_compiler, Mode::ToolRustc, target)
 474             .join(exe("rustdoc_tool_binary", &target_compiler.host));
 475
 476         // don't create a stage0-sysroot/bin directory.
 477         if target_compiler.stage > 0 {
 478             let sysroot = builder.sysroot(target_compiler);
 479             let bindir = sysroot.join("bin");
 480             t!(fs::create_dir_all(&bindir));
 481             let bin_rustdoc = bindir.join(exe("rustdoc", &*target_compiler.host));
 482             let _ = fs::remove_file(&bin_rustdoc);
 483             builder.copy(&tool_rustdoc, &bin_rustdoc);
 484             bin_rustdoc
 485         } else {
 486             tool_rustdoc
 487         }
 488     }
 489 }
 490
 491 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 492 pub struct Cargo {
 493     pub compiler: Compiler,
 494     pub target: Interned<String>,
 495 }
 496
 497 impl Step for Cargo {
 498     type Output = PathBuf;
 499     const DEFAULT: bool = true;
 500     const ONLY_HOSTS: bool = true;
 501
 502     fn should_run(run: ShouldRun) -> ShouldRun {
 503         let builder = run.builder;
 504         run.path("src/tools/cargo").default_condition(builder.config.extended)
 505     }
 506
 507     fn make_run(run: RunConfig) {
 508         run.builder.ensure(Cargo {
 509             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 510             target: run.target,
 511         });
 512     }
 513
 514     fn run(self, builder: &Builder) -> PathBuf {
 515         // Cargo depends on procedural macros, which requires a full host
 516         // compiler to be available, so we need to depend on that.
 517         builder.ensure(compile::Rustc {
 518             compiler: self.compiler,
 519             target: builder.config.build,
 520         });
 521         builder.ensure(ToolBuild {
 522             compiler: self.compiler,
 523             target: self.target,
 524             tool: "cargo",
 525             mode: Mode::ToolRustc,
 526             path: "src/tools/cargo",
 527             is_optional_tool: false,
 528             source_type: SourceType::Submodule,
 529             extra_features: Vec::new(),
 530         }).expect("expected to build -- essential tool")
 531     }
 532 }
 533
 534 macro_rules! tool_extended {
 535     (($sel:ident, $builder:ident),
 536        $($name:ident,
 537        $toolstate:ident,
 538        $path:expr,
 539        $tool_name:expr,
 540        $extra_deps:block;)+) => {
 541         $(
 542             #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 543         pub struct $name {
 544             pub compiler: Compiler,
 545             pub target: Interned<String>,
 546             pub extra_features: Vec<String>,
 547         }
 548
 549         impl Step for $name {
 550             type Output = Option<PathBuf>;
 551             const DEFAULT: bool = true;
 552             const ONLY_HOSTS: bool = true;
 553
 554             fn should_run(run: ShouldRun) -> ShouldRun {
 555                 let builder = run.builder;
 556                 run.path($path).default_condition(builder.config.extended)
 557             }
 558
 559             fn make_run(run: RunConfig) {
 560                 run.builder.ensure($name {
 561                     compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
 562                     target: run.target,
 563                     extra_features: Vec::new(),
 564                 });
 565             }
 566
 567             #[allow(unused_mut)]
 568             fn run(mut $sel, $builder: &Builder) -> Option<PathBuf> {
 569                 $extra_deps
 570                 $builder.ensure(ToolBuild {
 571                     compiler: $sel.compiler,
 572                     target: $sel.target,
 573                     tool: $tool_name,
 574                     mode: Mode::ToolRustc,
 575                     path: $path,
 576                     extra_features: $sel.extra_features,
 577                     is_optional_tool: true,
 578                     source_type: SourceType::Submodule,
 579                 })
 580             }
 581         }
 582         )+
 583     }
 584 }
 585
 586 tool_extended!((self, builder),
 587     Cargofmt, rustfmt, "src/tools/rustfmt", "cargo-fmt", {};
 588     CargoClippy, clippy, "src/tools/clippy", "cargo-clippy", {
 589         // Clippy depends on procedural macros (serde), which requires a full host
 590         // compiler to be available, so we need to depend on that.
 591         builder.ensure(compile::Rustc {
 592             compiler: self.compiler,
 593             target: builder.config.build,
 594         });
 595     };
 596     Clippy, clippy, "src/tools/clippy", "clippy-driver", {
 597         // Clippy depends on procedural macros (serde), which requires a full host
 598         // compiler to be available, so we need to depend on that.
 599         builder.ensure(compile::Rustc {
 600             compiler: self.compiler,
 601             target: builder.config.build,
 602         });
 603     };
 604     Miri, miri, "src/tools/miri", "miri", {};
 605     Rls, rls, "src/tools/rls", "rls", {
 606         let clippy = builder.ensure(Clippy {
 607             compiler: self.compiler,
 608             target: self.target,
 609             extra_features: Vec::new(),
 610         });
 611         if clippy.is_some() {
 612             self.extra_features.push("clippy".to_owned());
 613         }
 614         // RLS depends on procedural macros, which requires a full host
 615         // compiler to be available, so we need to depend on that.
 616         builder.ensure(compile::Rustc {
 617             compiler: self.compiler,
 618             target: builder.config.build,
 619         });
 620     };
 621     Rustfmt, rustfmt, "src/tools/rustfmt", "rustfmt", {};
 622 );
 623
 624 impl<'a> Builder<'a> {
 625     /// Get a `Command` which is ready to run `tool` in `stage` built for
 626     /// `host`.
 627     pub fn tool_cmd(&self, tool: Tool) -> Command {
 628         let mut cmd = Command::new(self.tool_exe(tool));
 629         let compiler = self.compiler(self.tool_default_stage(tool), self.config.build);
 630         self.prepare_tool_cmd(compiler, tool, &mut cmd);
 631         cmd
 632     }
 633
 634     /// Prepares the `cmd` provided to be able to run the `compiler` provided.
 635     ///
 636     /// Notably this munges the dynamic library lookup path to point to the
 637     /// right location to run `compiler`.
 638     fn prepare_tool_cmd(&self, compiler: Compiler, tool: Tool, cmd: &mut Command) {
 639         let host = &compiler.host;
 640         let mut lib_paths: Vec<PathBuf> = vec![
 641             if compiler.stage == 0 && tool != Tool::ErrorIndex {
 642                 self.build.rustc_snapshot_libdir()
 643             } else {
 644                 PathBuf::from(&self.sysroot_libdir(compiler, compiler.host))
 645             },
 646             self.cargo_out(compiler, tool.get_mode(), *host).join("deps"),
 647         ];
 648
 649         // On MSVC a tool may invoke a C compiler (e.g. compiletest in run-make
 650         // mode) and that C compiler may need some extra PATH modification. Do
 651         // so here.
 652         if compiler.host.contains("msvc") {
 653             let curpaths = env::var_os("PATH").unwrap_or_default();
 654             let curpaths = env::split_paths(&curpaths).collect::<Vec<_>>();
 655             for &(ref k, ref v) in self.cc[&compiler.host].env() {
 656                 if k != "PATH" {
 657                     continue
 658                 }
 659                 for path in env::split_paths(v) {
 660                     if !curpaths.contains(&path) {
 661                         lib_paths.push(path);
 662                     }
 663                 }
 664             }
 665         }
 666
 667         // Add the llvm/bin directory to PATH since it contains lots of
 668         // useful, platform-independent tools
 669         if tool.uses_llvm_tools() {
 670             if let Some(llvm_bin_path) = self.llvm_bin_path() {
 671                 if host.contains("windows") {
 672                     // On Windows, PATH and the dynamic library path are the same,
 673                     // so we just add the LLVM bin path to lib_path
 674                     lib_paths.push(llvm_bin_path);
 675                 } else {
 676                     let old_path = env::var_os("PATH").unwrap_or_default();
 677                     let new_path = env::join_paths(iter::once(llvm_bin_path)
 678                             .chain(env::split_paths(&old_path)))
 679                         .expect("Could not add LLVM bin path to PATH");
 680                     cmd.env("PATH", new_path);
 681                 }
 682             }
 683         }
 684
 685         add_lib_path(lib_paths, cmd);
 686     }
 687
 688     fn llvm_bin_path(&self) -> Option<PathBuf> {
 689         if self.config.llvm_enabled && !self.config.dry_run {
 690             let llvm_config = self.ensure(native::Llvm {
 691                 target: self.config.build,
 692                 emscripten: false,
 693             });
 694
 695             // Add the llvm/bin directory to PATH since it contains lots of
 696             // useful, platform-independent tools
 697             let llvm_bin_path = llvm_config.parent()
 698                 .expect("Expected llvm-config to be contained in directory");
 699             assert!(llvm_bin_path.is_dir());
 700             Some(llvm_bin_path.to_path_buf())
 701         } else {
 702             None
 703         }
 704     }
 705 }