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1 use std::collections::HashSet;
2 use std::env;
3 use std::fs;
4 use std::path::PathBuf;
5 use std::process::{exit, Command};
6
7 use build_helper::t;
8
9 use crate::builder::{Builder, Cargo as CargoCommand, RunConfig, ShouldRun, Step};
10 use crate::channel;
11 use crate::channel::GitInfo;
12 use crate::compile;
13 use crate::config::TargetSelection;
14 use crate::toolstate::ToolState;
15 use crate::util::{add_dylib_path, exe};
16 use crate::Compiler;
17 use crate::Mode;
18
19 #[derive(Debug, Copy, 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: TargetSelection,
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     /// Builds 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 => builder.ensure(compile::Rustc { compiler, target }),
57             Mode::ToolStd => builder.ensure(compile::Std { compiler, target }),
58             Mode::ToolBootstrap => {} // uses downloaded stage0 compiler libs
59             _ => panic!("unexpected Mode for tool build"),
60         }
61
62         let cargo = prepare_tool_cargo(
63             builder,
64             compiler,
65             self.mode,
66             target,
67             "build",
68             path,
69             self.source_type,
70             &self.extra_features,
71         );
72
73         builder.info(&format!("Building stage{} tool {} ({})", compiler.stage, tool, target));
74         let mut duplicates = Vec::new();
75         let is_expected = compile::stream_cargo(builder, cargo, vec![], &mut |msg| {
76             // Only care about big things like the RLS/Cargo for now
77             match tool {
78                 "rls" | "cargo" | "clippy-driver" | "miri" | "rustfmt" => {}
79
80                 _ => return,
81             }
82             let (id, features, filenames) = match msg {
83                 compile::CargoMessage::CompilerArtifact {
84                     package_id,
85                     features,
86                     filenames,
87                     target: _,
88                 } => (package_id, features, filenames),
89                 _ => return,
90             };
91             let features = features.iter().map(|s| s.to_string()).collect::<Vec<_>>();
92
93             for path in filenames {
94                 let val = (tool, PathBuf::from(&*path), features.clone());
95                 // we're only interested in deduplicating rlibs for now
96                 if val.1.extension().and_then(|s| s.to_str()) != Some("rlib") {
97                     continue;
98                 }
99
100                 // Don't worry about compiles that turn out to be host
101                 // dependencies or build scripts. To skip these we look for
102                 // anything that goes in `.../release/deps` but *doesn't* go in
103                 // `$target/release/deps`. This ensure that outputs in
104                 // `$target/release` are still considered candidates for
105                 // deduplication.
106                 if let Some(parent) = val.1.parent() {
107                     if parent.ends_with("release/deps") {
108                         let maybe_target = parent
109                             .parent()
110                             .and_then(|p| p.parent())
111                             .and_then(|p| p.file_name())
112                             .and_then(|p| p.to_str())
113                             .unwrap();
114                         if maybe_target != &*target.triple {
115                             continue;
116                         }
117                     }
118                 }
119
120                 // Record that we've built an artifact for `id`, and if one was
121                 // already listed then we need to see if we reused the same
122                 // artifact or produced a duplicate.
123                 let mut artifacts = builder.tool_artifacts.borrow_mut();
124                 let prev_artifacts = artifacts.entry(target).or_default();
125                 let prev = match prev_artifacts.get(&*id) {
126                     Some(prev) => prev,
127                     None => {
128                         prev_artifacts.insert(id.to_string(), val);
129                         continue;
130                     }
131                 };
132                 if prev.1 == val.1 {
133                     return; // same path, same artifact
134                 }
135
136                 // If the paths are different and one of them *isn't* inside of
137                 // `release/deps`, then it means it's probably in
138                 // `$target/release`, or it's some final artifact like
139                 // `libcargo.rlib`. In these situations Cargo probably just
140                 // copied it up from `$target/release/deps/libcargo-xxxx.rlib`,
141                 // so if the features are equal we can just skip it.
142                 let prev_no_hash = prev.1.parent().unwrap().ends_with("release/deps");
143                 let val_no_hash = val.1.parent().unwrap().ends_with("release/deps");
144                 if prev.2 == val.2 || !prev_no_hash || !val_no_hash {
145                     return;
146                 }
147
148                 // ... and otherwise this looks like we duplicated some sort of
149                 // compilation, so record it to generate an error later.
150                 duplicates.push((id.to_string(), val, prev.clone()));
151             }
152         });
153
154         if is_expected && !duplicates.is_empty() {
155             println!(
156                 "duplicate artifacts found when compiling a tool, this \
157                       typically means that something was recompiled because \
158                       a transitive dependency has different features activated \
159                       than in a previous build:\n"
160             );
161             println!(
162                 "the following dependencies are duplicated although they \
163                       have the same features enabled:"
164             );
165             let (same, different): (Vec<_>, Vec<_>) =
166                 duplicates.into_iter().partition(|(_, cur, prev)| cur.2 == prev.2);
167             for (id, cur, prev) in same {
168                 println!("  {}", id);
169                 // same features
170                 println!("    `{}` ({:?})\n    `{}` ({:?})", cur.0, cur.1, prev.0, prev.1);
171             }
172             println!("the following dependencies have different features:");
173             for (id, cur, prev) in different {
174                 println!("  {}", id);
175                 let cur_features: HashSet<_> = cur.2.into_iter().collect();
176                 let prev_features: HashSet<_> = prev.2.into_iter().collect();
177                 println!(
178                     "    `{}` additionally enabled features {:?} at {:?}",
179                     cur.0,
180                     &cur_features - &prev_features,
181                     cur.1
182                 );
183                 println!(
184                     "    `{}` additionally enabled features {:?} at {:?}",
185                     prev.0,
186                     &prev_features - &cur_features,
187                     prev.1
188                 );
189             }
190             println!();
191             println!(
192                 "to fix this you will probably want to edit the local \
193                       src/tools/rustc-workspace-hack/Cargo.toml crate, as \
194                       that will update the dependency graph to ensure that \
195                       these crates all share the same feature set"
196             );
197             panic!("tools should not compile multiple copies of the same crate");
198         }
199
200         builder.save_toolstate(
201             tool,
202             if is_expected { ToolState::TestFail } else { ToolState::BuildFail },
203         );
204
205         if !is_expected {
206             if !is_optional_tool {
207                 exit(1);
208             } else {
209                 None
210             }
211         } else {
212             let cargo_out =
213                 builder.cargo_out(compiler, self.mode, target).join(exe(tool, compiler.host));
214             let bin = builder.tools_dir(compiler).join(exe(tool, compiler.host));
215             builder.copy(&cargo_out, &bin);
216             Some(bin)
217         }
218     }
219 }
220
221 pub fn prepare_tool_cargo(
222     builder: &Builder<'_>,
223     compiler: Compiler,
224     mode: Mode,
225     target: TargetSelection,
226     command: &'static str,
227     path: &'static str,
228     source_type: SourceType,
229     extra_features: &[String],
230 ) -> CargoCommand {
231     let mut cargo = builder.cargo(compiler, mode, source_type, target, command);
232     let dir = builder.src.join(path);
233     cargo.arg("--manifest-path").arg(dir.join("Cargo.toml"));
234
235     let mut features = extra_features.to_vec();
236     if builder.build.config.cargo_native_static {
237         if path.ends_with("cargo")
238             || path.ends_with("rls")
239             || path.ends_with("clippy")
240             || path.ends_with("miri")
241             || path.ends_with("rustfmt")
242         {
243             cargo.env("LIBZ_SYS_STATIC", "1");
244             features.push("rustc-workspace-hack/all-static".to_string());
245         }
246     }
247
248     // if tools are using lzma we want to force the build script to build its
249     // own copy
250     cargo.env("LZMA_API_STATIC", "1");
251
252     // CFG_RELEASE is needed by rustfmt (and possibly other tools) which
253     // import rustc-ap-rustc_attr which requires this to be set for the
254     // `#[cfg(version(...))]` attribute.
255     cargo.env("CFG_RELEASE", builder.rust_release());
256     cargo.env("CFG_RELEASE_CHANNEL", &builder.config.channel);
257     cargo.env("CFG_VERSION", builder.rust_version());
258     cargo.env("CFG_RELEASE_NUM", channel::CFG_RELEASE_NUM);
259
260     let info = GitInfo::new(builder.config.ignore_git, &dir);
261     if let Some(sha) = info.sha() {
262         cargo.env("CFG_COMMIT_HASH", sha);
263     }
264     if let Some(sha_short) = info.sha_short() {
265         cargo.env("CFG_SHORT_COMMIT_HASH", sha_short);
266     }
267     if let Some(date) = info.commit_date() {
268         cargo.env("CFG_COMMIT_DATE", date);
269     }
270     if !features.is_empty() {
271         cargo.arg("--features").arg(&features.join(", "));
272     }
273     cargo
274 }
275
276 macro_rules! bootstrap_tool {
277     ($(
278         $name:ident, $path:expr, $tool_name:expr
279         $(,is_external_tool = $external:expr)*
280         $(,is_unstable_tool = $unstable:expr)*
281         $(,features = $features:expr)*
282         ;
283     )+) => {
284         #[derive(Copy, PartialEq, Eq, Clone)]
285         pub enum Tool {
286             $(
287                 $name,
288             )+
289         }
290
291         impl<'a> Builder<'a> {
292             pub fn tool_exe(&self, tool: Tool) -> PathBuf {
293                 match tool {
294                     $(Tool::$name =>
295                         self.ensure($name {
296                             compiler: self.compiler(0, self.config.build),
297                             target: self.config.build,
298                         }),
299                     )+
300                 }
301             }
302         }
303
304         $(
305             #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
306         pub struct $name {
307             pub compiler: Compiler,
308             pub target: TargetSelection,
309         }
310
311         impl Step for $name {
312             type Output = PathBuf;
313
314             fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
315                 run.path($path)
316             }
317
318             fn make_run(run: RunConfig<'_>) {
319                 run.builder.ensure($name {
320                     // snapshot compiler
321                     compiler: run.builder.compiler(0, run.builder.config.build),
322                     target: run.target,
323                 });
324             }
325
326             fn run(self, builder: &Builder<'_>) -> PathBuf {
327                 builder.ensure(ToolBuild {
328                     compiler: self.compiler,
329                     target: self.target,
330                     tool: $tool_name,
331                     mode: if false $(|| $unstable)* {
332                         // use in-tree libraries for unstable features
333                         Mode::ToolStd
334                     } else {
335                         Mode::ToolBootstrap
336                     },
337                     path: $path,
338                     is_optional_tool: false,
339                     source_type: if false $(|| $external)* {
340                         SourceType::Submodule
341                     } else {
342                         SourceType::InTree
343                     },
344                     extra_features: {
345                         // FIXME(#60643): avoid this lint by using `_`
346                         let mut _tmp = Vec::new();
347                         $(_tmp.extend($features);)*
348                         _tmp
349                     },
350                 }).expect("expected to build -- essential tool")
351             }
352         }
353         )+
354     }
355 }
356
357 bootstrap_tool!(
358     Rustbook, "src/tools/rustbook", "rustbook";
359     UnstableBookGen, "src/tools/unstable-book-gen", "unstable-book-gen";
360     Tidy, "src/tools/tidy", "tidy";
361     Linkchecker, "src/tools/linkchecker", "linkchecker";
362     CargoTest, "src/tools/cargotest", "cargotest";
363     Compiletest, "src/tools/compiletest", "compiletest", is_unstable_tool = true;
364     BuildManifest, "src/tools/build-manifest", "build-manifest";
365     RemoteTestClient, "src/tools/remote-test-client", "remote-test-client";
366     RustDemangler, "src/tools/rust-demangler", "rust-demangler";
367     RustInstaller, "src/tools/rust-installer", "fabricate", is_external_tool = true;
368     RustdocTheme, "src/tools/rustdoc-themes", "rustdoc-themes";
369     ExpandYamlAnchors, "src/tools/expand-yaml-anchors", "expand-yaml-anchors";
370 );
371
372 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
373 pub struct ErrorIndex {
374     pub compiler: Compiler,
375 }
376
377 impl ErrorIndex {
378     pub fn command(builder: &Builder<'_>, compiler: Compiler) -> Command {
379         let mut cmd = Command::new(builder.ensure(ErrorIndex { compiler }));
380         add_dylib_path(
381             vec![PathBuf::from(&builder.sysroot_libdir(compiler, compiler.host))],
382             &mut cmd,
383         );
384         cmd
385     }
386 }
387
388 impl Step for ErrorIndex {
389     type Output = PathBuf;
390
391     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
392         run.path("src/tools/error_index_generator")
393     }
394
395     fn make_run(run: RunConfig<'_>) {
396         // Compile the error-index in the same stage as rustdoc to avoid
397         // recompiling rustdoc twice if we can.
398         let host = run.builder.config.build;
399         let compiler = run.builder.compiler_for(run.builder.top_stage, host, host);
400         run.builder.ensure(ErrorIndex { compiler });
401     }
402
403     fn run(self, builder: &Builder<'_>) -> PathBuf {
404         builder
405             .ensure(ToolBuild {
406                 compiler: self.compiler,
407                 target: self.compiler.host,
408                 tool: "error_index_generator",
409                 mode: Mode::ToolRustc,
410                 path: "src/tools/error_index_generator",
411                 is_optional_tool: false,
412                 source_type: SourceType::InTree,
413                 extra_features: Vec::new(),
414             })
415             .expect("expected to build -- essential tool")
416     }
417 }
418
419 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
420 pub struct RemoteTestServer {
421     pub compiler: Compiler,
422     pub target: TargetSelection,
423 }
424
425 impl Step for RemoteTestServer {
426     type Output = PathBuf;
427
428     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
429         run.path("src/tools/remote-test-server")
430     }
431
432     fn make_run(run: RunConfig<'_>) {
433         run.builder.ensure(RemoteTestServer {
434             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
435             target: run.target,
436         });
437     }
438
439     fn run(self, builder: &Builder<'_>) -> PathBuf {
440         builder
441             .ensure(ToolBuild {
442                 compiler: self.compiler,
443                 target: self.target,
444                 tool: "remote-test-server",
445                 mode: Mode::ToolStd,
446                 path: "src/tools/remote-test-server",
447                 is_optional_tool: false,
448                 source_type: SourceType::InTree,
449                 extra_features: Vec::new(),
450             })
451             .expect("expected to build -- essential tool")
452     }
453 }
454
455 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
456 pub struct Rustdoc {
457     /// This should only ever be 0 or 2.
458     /// We sometimes want to reference the "bootstrap" rustdoc, which is why this option is here.
459     pub compiler: Compiler,
460 }
461
462 impl Step for Rustdoc {
463     type Output = PathBuf;
464     const DEFAULT: bool = true;
465     const ONLY_HOSTS: bool = true;
466
467     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
468         run.path("src/tools/rustdoc").path("src/librustdoc")
469     }
470
471     fn make_run(run: RunConfig<'_>) {
472         run.builder.ensure(Rustdoc {
473             compiler: run.builder.compiler(run.builder.top_stage, run.build_triple()),
474         });
475     }
476
477     fn run(self, builder: &Builder<'_>) -> PathBuf {
478         let target_compiler = self.compiler;
479         if target_compiler.stage == 0 {
480             if !target_compiler.is_snapshot(builder) {
481                 panic!("rustdoc in stage 0 must be snapshot rustdoc");
482             }
483             return builder.initial_rustc.with_file_name(exe("rustdoc", target_compiler.host));
484         }
485         let target = target_compiler.host;
486         // Similar to `compile::Assemble`, build with the previous stage's compiler. Otherwise
487         // we'd have stageN/bin/rustc and stageN/bin/rustdoc be effectively different stage
488         // compilers, which isn't what we want. Rustdoc should be linked in the same way as the
489         // rustc compiler it's paired with, so it must be built with the previous stage compiler.
490         let build_compiler = builder.compiler(target_compiler.stage - 1, builder.config.build);
491
492         // The presence of `target_compiler` ensures that the necessary libraries (codegen backends,
493         // compiler libraries, ...) are built. Rustdoc does not require the presence of any
494         // libraries within sysroot_libdir (i.e., rustlib), though doctests may want it (since
495         // they'll be linked to those libraries). As such, don't explicitly `ensure` any additional
496         // libraries here. The intuition here is that If we've built a compiler, we should be able
497         // to build rustdoc.
498
499         let cargo = prepare_tool_cargo(
500             builder,
501             build_compiler,
502             Mode::ToolRustc,
503             target,
504             "build",
505             "src/tools/rustdoc",
506             SourceType::InTree,
507             &[],
508         );
509
510         builder.info(&format!(
511             "Building rustdoc for stage{} ({})",
512             target_compiler.stage, target_compiler.host
513         ));
514         builder.run(&mut cargo.into());
515
516         // Cargo adds a number of paths to the dylib search path on windows, which results in
517         // the wrong rustdoc being executed. To avoid the conflicting rustdocs, we name the "tool"
518         // rustdoc a different name.
519         let tool_rustdoc = builder
520             .cargo_out(build_compiler, Mode::ToolRustc, target)
521             .join(exe("rustdoc_tool_binary", target_compiler.host));
522
523         // don't create a stage0-sysroot/bin directory.
524         if target_compiler.stage > 0 {
525             let sysroot = builder.sysroot(target_compiler);
526             let bindir = sysroot.join("bin");
527             t!(fs::create_dir_all(&bindir));
528             let bin_rustdoc = bindir.join(exe("rustdoc", target_compiler.host));
529             let _ = fs::remove_file(&bin_rustdoc);
530             builder.copy(&tool_rustdoc, &bin_rustdoc);
531             bin_rustdoc
532         } else {
533             tool_rustdoc
534         }
535     }
536 }
537
538 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
539 pub struct Cargo {
540     pub compiler: Compiler,
541     pub target: TargetSelection,
542 }
543
544 impl Step for Cargo {
545     type Output = PathBuf;
546     const DEFAULT: bool = true;
547     const ONLY_HOSTS: bool = true;
548
549     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
550         let builder = run.builder;
551         run.path("src/tools/cargo").default_condition(builder.config.extended)
552     }
553
554     fn make_run(run: RunConfig<'_>) {
555         run.builder.ensure(Cargo {
556             compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
557             target: run.target,
558         });
559     }
560
561     fn run(self, builder: &Builder<'_>) -> PathBuf {
562         builder
563             .ensure(ToolBuild {
564                 compiler: self.compiler,
565                 target: self.target,
566                 tool: "cargo",
567                 mode: Mode::ToolRustc,
568                 path: "src/tools/cargo",
569                 is_optional_tool: false,
570                 source_type: SourceType::Submodule,
571                 extra_features: Vec::new(),
572             })
573             .expect("expected to build -- essential tool")
574     }
575 }
576
577 macro_rules! tool_extended {
578     (($sel:ident, $builder:ident),
579        $($name:ident,
580        $toolstate:ident,
581        $path:expr,
582        $tool_name:expr,
583        stable = $stable:expr,
584        $(in_tree = $in_tree:expr,)*
585        $extra_deps:block;)+) => {
586         $(
587             #[derive(Debug, Clone, Hash, PartialEq, Eq)]
588         pub struct $name {
589             pub compiler: Compiler,
590             pub target: TargetSelection,
591             pub extra_features: Vec<String>,
592         }
593
594         impl Step for $name {
595             type Output = Option<PathBuf>;
596             const DEFAULT: bool = true; // Overwritten below
597             const ONLY_HOSTS: bool = true;
598
599             fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
600                 let builder = run.builder;
601                 run.path($path).default_condition(
602                     builder.config.extended
603                         && builder.config.tools.as_ref().map_or(
604                             // By default, on nightly/dev enable all tools, else only
605                             // build stable tools.
606                             $stable || builder.build.unstable_features(),
607                             // If `tools` is set, search list for this tool.
608                             |tools| {
609                                 tools.iter().any(|tool| match tool.as_ref() {
610                                     "clippy" => $tool_name == "clippy-driver",
611                                     x => $tool_name == x,
612                             })
613                         }),
614                 )
615             }
616
617             fn make_run(run: RunConfig<'_>) {
618                 run.builder.ensure($name {
619                     compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
620                     target: run.target,
621                     extra_features: Vec::new(),
622                 });
623             }
624
625             #[allow(unused_mut)]
626             fn run(mut $sel, $builder: &Builder<'_>) -> Option<PathBuf> {
627                 $extra_deps
628                 $builder.ensure(ToolBuild {
629                     compiler: $sel.compiler,
630                     target: $sel.target,
631                     tool: $tool_name,
632                     mode: Mode::ToolRustc,
633                     path: $path,
634                     extra_features: $sel.extra_features,
635                     is_optional_tool: true,
636                     source_type: if false $(|| $in_tree)* {
637                         SourceType::InTree
638                     } else {
639                         SourceType::Submodule
640                     },
641                 })
642             }
643         }
644         )+
645     }
646 }
647
648 // Note: tools need to be also added to `Builder::get_step_descriptions` in `builder.rs`
649 // to make `./x.py build <tool>` work.
650 tool_extended!((self, builder),
651     Cargofmt, rustfmt, "src/tools/rustfmt", "cargo-fmt", stable=true, {};
652     CargoClippy, clippy, "src/tools/clippy", "cargo-clippy", stable=true, in_tree=true, {};
653     Clippy, clippy, "src/tools/clippy", "clippy-driver", stable=true, in_tree=true, {};
654     Miri, miri, "src/tools/miri", "miri", stable=false, {};
655     CargoMiri, miri, "src/tools/miri/cargo-miri", "cargo-miri", stable=false, {};
656     Rls, rls, "src/tools/rls", "rls", stable=true, {
657         builder.ensure(Clippy {
658             compiler: self.compiler,
659             target: self.target,
660             extra_features: Vec::new(),
661         });
662         self.extra_features.push("clippy".to_owned());
663     };
664     Rustfmt, rustfmt, "src/tools/rustfmt", "rustfmt", stable=true, {};
665     RustAnalyzer, rust_analyzer, "src/tools/rust-analyzer/crates/rust-analyzer", "rust-analyzer", stable=false, {};
666 );
667
668 impl<'a> Builder<'a> {
669     /// Gets a `Command` which is ready to run `tool` in `stage` built for
670     /// `host`.
671     pub fn tool_cmd(&self, tool: Tool) -> Command {
672         let mut cmd = Command::new(self.tool_exe(tool));
673         let compiler = self.compiler(0, self.config.build);
674         let host = &compiler.host;
675         // Prepares the `cmd` provided to be able to run the `compiler` provided.
676         //
677         // Notably this munges the dynamic library lookup path to point to the
678         // right location to run `compiler`.
679         let mut lib_paths: Vec<PathBuf> = vec![
680             self.build.rustc_snapshot_libdir(),
681             self.cargo_out(compiler, Mode::ToolBootstrap, *host).join("deps"),
682         ];
683
684         // On MSVC a tool may invoke a C compiler (e.g., compiletest in run-make
685         // mode) and that C compiler may need some extra PATH modification. Do
686         // so here.
687         if compiler.host.contains("msvc") {
688             let curpaths = env::var_os("PATH").unwrap_or_default();
689             let curpaths = env::split_paths(&curpaths).collect::<Vec<_>>();
690             for &(ref k, ref v) in self.cc[&compiler.host].env() {
691                 if k != "PATH" {
692                     continue;
693                 }
694                 for path in env::split_paths(v) {
695                     if !curpaths.contains(&path) {
696                         lib_paths.push(path);
697                     }
698                 }
699             }
700         }
701
702         add_dylib_path(lib_paths, &mut cmd);
703         cmd
704     }
705 }