bootstrap/core/build_steps/

tool.rs

//! This module handles building and managing various tools in bootstrap
//! build system.
//!
//! **What It Does**
//! - Defines how tools are built, configured and installed.
//! - Manages tool dependencies and build steps.
//! - Copies built tool binaries to the correct locations.
//!
//! Each Rust tool **MUST** utilize `ToolBuild` inside their `Step` logic,
//! return `ToolBuildResult` and should never prepare `cargo` invocations manually.

use std::path::PathBuf;
use std::{env, fs};

#[cfg(feature = "tracing")]
use tracing::instrument;

use crate::core::build_steps::compile::is_lto_stage;
use crate::core::build_steps::toolstate::ToolState;
use crate::core::build_steps::{compile, llvm};
use crate::core::builder;
use crate::core::builder::{
    Builder, Cargo as CargoCommand, RunConfig, ShouldRun, Step, cargo_profile_var,
};
use crate::core::config::{DebuginfoLevel, RustcLto, TargetSelection};
use crate::utils::channel::GitInfo;
use crate::utils::exec::{BootstrapCommand, command};
use crate::utils::helpers::{add_dylib_path, exe, t};
use crate::{Compiler, Kind, Mode, gha};

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub enum SourceType {
    InTree,
    Submodule,
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub enum ToolArtifactKind {
    Binary,
    Library,
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
struct ToolBuild {
    compiler: Compiler,
    target: TargetSelection,
    tool: &'static str,
    path: &'static str,
    mode: Mode,
    source_type: SourceType,
    extra_features: Vec<String>,
    /// Nightly-only features that are allowed (comma-separated list).
    allow_features: &'static str,
    /// Additional arguments to pass to the `cargo` invocation.
    cargo_args: Vec<String>,
    /// Whether the tool builds a binary or a library.
    artifact_kind: ToolArtifactKind,
}

impl Builder<'_> {
    #[track_caller]
    pub(crate) fn msg_tool(
        &self,
        kind: Kind,
        mode: Mode,
        tool: &str,
        build_stage: u32,
        host: &TargetSelection,
        target: &TargetSelection,
    ) -> Option<gha::Group> {
        match mode {
            // depends on compiler stage, different to host compiler
            Mode::ToolRustc => self.msg_sysroot_tool(
                kind,
                build_stage,
                format_args!("tool {tool}"),
                *host,
                *target,
            ),
            // doesn't depend on compiler, same as host compiler
            _ => self.msg(Kind::Build, build_stage, format_args!("tool {tool}"), *host, *target),
        }
    }
}

/// Result of the tool build process. Each `Step` in this module is responsible
/// for using this type as `type Output = ToolBuildResult;`
#[derive(Clone)]
pub struct ToolBuildResult {
    /// Artifact path of the corresponding tool that was built.
    pub tool_path: PathBuf,
    /// Compiler used to build the tool. For non-`ToolRustc` tools this is equal to `target_compiler`.
    /// For `ToolRustc` this is one stage before of the `target_compiler`.
    pub build_compiler: Compiler,
    /// Target compiler passed to `Step`.
    pub target_compiler: Compiler,
}

impl Step for ToolBuild {
    type Output = ToolBuildResult;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.never()
    }

    /// Builds a tool in `src/tools`
    ///
    /// This will build the specified tool with the specified `host` compiler in
    /// `stage` into the normal cargo output directory.
    fn run(mut self, builder: &Builder<'_>) -> ToolBuildResult {
        let target = self.target;
        let mut tool = self.tool;
        let path = self.path;

        let target_compiler = self.compiler;
        self.compiler = if self.mode == Mode::ToolRustc {
            get_tool_rustc_compiler(builder, self.compiler)
        } else {
            self.compiler
        };

        match self.mode {
            Mode::ToolRustc => {
                // If compiler was forced, its artifacts should be prepared earlier.
                if !self.compiler.is_forced_compiler() {
                    builder.ensure(compile::Std::new(self.compiler, self.compiler.host));
                    builder.ensure(compile::Rustc::new(self.compiler, target));
                }
            }
            Mode::ToolStd => {
                // If compiler was forced, its artifacts should be prepared earlier.
                if !self.compiler.is_forced_compiler() {
                    builder.ensure(compile::Std::new(self.compiler, target))
                }
            }
            Mode::ToolBootstrap => {} // uses downloaded stage0 compiler libs
            _ => panic!("unexpected Mode for tool build"),
        }

        let mut cargo = prepare_tool_cargo(
            builder,
            self.compiler,
            self.mode,
            target,
            Kind::Build,
            path,
            self.source_type,
            &self.extra_features,
        );

        if path.ends_with("/rustdoc") &&
            // rustdoc is performance sensitive, so apply LTO to it.
            is_lto_stage(&self.compiler)
        {
            let lto = match builder.config.rust_lto {
                RustcLto::Off => Some("off"),
                RustcLto::Thin => Some("thin"),
                RustcLto::Fat => Some("fat"),
                RustcLto::ThinLocal => None,
            };
            if let Some(lto) = lto {
                cargo.env(cargo_profile_var("LTO", &builder.config), lto);
            }
        }

        if !self.allow_features.is_empty() {
            cargo.allow_features(self.allow_features);
        }

        cargo.args(self.cargo_args);

        let _guard = builder.msg_tool(
            Kind::Build,
            self.mode,
            self.tool,
            self.compiler.stage,
            &self.compiler.host,
            &self.target,
        );

        // we check this below
        let build_success = compile::stream_cargo(builder, cargo, vec![], &mut |_| {});

        builder.save_toolstate(
            tool,
            if build_success { ToolState::TestFail } else { ToolState::BuildFail },
        );

        if !build_success {
            crate::exit!(1);
        } else {
            // HACK(#82501): on Windows, the tools directory gets added to PATH when running tests, and
            // compiletest confuses HTML tidy with the in-tree tidy. Name the in-tree tidy something
            // different so the problem doesn't come up.
            if tool == "tidy" {
                tool = "rust-tidy";
            }
            let tool_path = match self.artifact_kind {
                ToolArtifactKind::Binary => {
                    copy_link_tool_bin(builder, self.compiler, self.target, self.mode, tool)
                }
                ToolArtifactKind::Library => builder
                    .cargo_out(self.compiler, self.mode, self.target)
                    .join(format!("lib{tool}.rlib")),
            };

            ToolBuildResult { tool_path, build_compiler: self.compiler, target_compiler }
        }
    }
}

#[expect(clippy::too_many_arguments)] // FIXME: reduce the number of args and remove this.
pub fn prepare_tool_cargo(
    builder: &Builder<'_>,
    compiler: Compiler,
    mode: Mode,
    target: TargetSelection,
    cmd_kind: Kind,
    path: &str,
    source_type: SourceType,
    extra_features: &[String],
) -> CargoCommand {
    let mut cargo = builder::Cargo::new(builder, compiler, mode, source_type, target, cmd_kind);

    let dir = builder.src.join(path);
    cargo.arg("--manifest-path").arg(dir.join("Cargo.toml"));

    let mut features = extra_features.to_vec();
    if builder.build.config.cargo_native_static {
        if path.ends_with("cargo")
            || path.ends_with("clippy")
            || path.ends_with("miri")
            || path.ends_with("rustfmt")
        {
            cargo.env("LIBZ_SYS_STATIC", "1");
        }
        if path.ends_with("cargo") {
            features.push("all-static".to_string());
        }
    }

    // clippy tests need to know about the stage sysroot. Set them consistently while building to
    // avoid rebuilding when running tests.
    cargo.env("SYSROOT", builder.sysroot(compiler));

    // if tools are using lzma we want to force the build script to build its
    // own copy
    cargo.env("LZMA_API_STATIC", "1");

    // CFG_RELEASE is needed by rustfmt (and possibly other tools) which
    // import rustc-ap-rustc_attr which requires this to be set for the
    // `#[cfg(version(...))]` attribute.
    cargo.env("CFG_RELEASE", builder.rust_release());
    cargo.env("CFG_RELEASE_CHANNEL", &builder.config.channel);
    cargo.env("CFG_VERSION", builder.rust_version());
    cargo.env("CFG_RELEASE_NUM", &builder.version);
    cargo.env("DOC_RUST_LANG_ORG_CHANNEL", builder.doc_rust_lang_org_channel());

    if let Some(ref ver_date) = builder.rust_info().commit_date() {
        cargo.env("CFG_VER_DATE", ver_date);
    }

    if let Some(ref ver_hash) = builder.rust_info().sha() {
        cargo.env("CFG_VER_HASH", ver_hash);
    }

    if let Some(description) = &builder.config.description {
        cargo.env("CFG_VER_DESCRIPTION", description);
    }

    let info = GitInfo::new(builder.config.omit_git_hash, &dir);
    if let Some(sha) = info.sha() {
        cargo.env("CFG_COMMIT_HASH", sha);
    }

    if let Some(sha_short) = info.sha_short() {
        cargo.env("CFG_SHORT_COMMIT_HASH", sha_short);
    }

    if let Some(date) = info.commit_date() {
        cargo.env("CFG_COMMIT_DATE", date);
    }

    if !features.is_empty() {
        cargo.arg("--features").arg(features.join(", "));
    }

    // Enable internal lints for clippy and rustdoc
    // NOTE: this doesn't enable lints for any other tools unless they explicitly add `#![warn(rustc::internal)]`
    // See https://github.com/rust-lang/rust/pull/80573#issuecomment-754010776
    //
    // NOTE: We unconditionally set this here to avoid recompiling tools between `x check $tool`
    // and `x test $tool` executions.
    // See https://github.com/rust-lang/rust/issues/116538
    cargo.rustflag("-Zunstable-options");

    // NOTE: The root cause of needing `-Zon-broken-pipe=kill` in the first place is because `rustc`
    // and `rustdoc` doesn't gracefully handle I/O errors due to usages of raw std `println!` macros
    // which panics upon encountering broken pipes. `-Zon-broken-pipe=kill` just papers over that
    // and stops rustc/rustdoc ICEing on e.g. `rustc --print=sysroot | false`.
    //
    // cargo explicitly does not want the `-Zon-broken-pipe=kill` paper because it does actually use
    // variants of `println!` that handles I/O errors gracefully. It's also a breaking change for a
    // spawn process not written in Rust, especially if the language default handler is not
    // `SIG_IGN`. Thankfully cargo tests will break if we do set the flag.
    //
    // For the cargo discussion, see
    // <https://rust-lang.zulipchat.com/#narrow/stream/246057-t-cargo/topic/Applying.20.60-Zon-broken-pipe.3Dkill.60.20flags.20in.20bootstrap.3F>.
    //
    // For the rustc discussion, see
    // <https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Internal.20lint.20for.20raw.20.60print!.60.20and.20.60println!.60.3F>
    // for proper solutions.
    if !path.ends_with("cargo") {
        // Use an untracked env var `FORCE_ON_BROKEN_PIPE_KILL` here instead of `RUSTFLAGS`.
        // `RUSTFLAGS` is tracked by cargo. Conditionally omitting `-Zon-broken-pipe=kill` from
        // `RUSTFLAGS` causes unnecessary tool rebuilds due to cache invalidation from building e.g.
        // cargo *without* `-Zon-broken-pipe=kill` but then rustdoc *with* `-Zon-broken-pipe=kill`.
        cargo.env("FORCE_ON_BROKEN_PIPE_KILL", "-Zon-broken-pipe=kill");
    }

    cargo
}

/// Handle stage-off logic for `ToolRustc` tools when necessary.
pub(crate) fn get_tool_rustc_compiler(
    builder: &Builder<'_>,
    target_compiler: Compiler,
) -> Compiler {
    if target_compiler.is_forced_compiler() {
        return target_compiler;
    }

    if builder.download_rustc() && target_compiler.stage > 0 {
        // We already have the stage N compiler, we don't need to cut the stage.
        return builder.compiler(target_compiler.stage, builder.config.build);
    }

    // Similar to `compile::Assemble`, build with the previous stage's compiler. Otherwise
    // we'd have stageN/bin/rustc and stageN/bin/$rustc_tool be effectively different stage
    // compilers, which isn't what we want. Rustc tools should be linked in the same way as the
    // compiler it's paired with, so it must be built with the previous stage compiler.
    builder.compiler(target_compiler.stage.saturating_sub(1), builder.config.build)
}

/// Links a built tool binary with the given `name` from the build directory to the
/// tools directory.
fn copy_link_tool_bin(
    builder: &Builder<'_>,
    compiler: Compiler,
    target: TargetSelection,
    mode: Mode,
    name: &str,
) -> PathBuf {
    let cargo_out = builder.cargo_out(compiler, mode, target).join(exe(name, target));
    let bin = builder.tools_dir(compiler).join(exe(name, target));
    builder.copy_link(&cargo_out, &bin);
    bin
}

macro_rules! bootstrap_tool {
    ($(
        $name:ident, $path:expr, $tool_name:expr
        $(,is_external_tool = $external:expr)*
        $(,is_unstable_tool = $unstable:expr)*
        $(,allow_features = $allow_features:expr)?
        $(,submodules = $submodules:expr)?
        $(,artifact_kind = $artifact_kind:expr)?
        ;
    )+) => {
        #[derive(PartialEq, Eq, Clone)]
        #[allow(dead_code)]
        pub enum Tool {
            $(
                $name,
            )+
        }

        impl<'a> Builder<'a> {
            pub fn tool_exe(&self, tool: Tool) -> PathBuf {
                match tool {
                    $(Tool::$name =>
                        self.ensure($name {
                            compiler: self.compiler(0, self.config.build),
                            target: self.config.build,
                        }).tool_path,
                    )+
                }
            }
        }

        $(
            #[derive(Debug, Clone, Hash, PartialEq, Eq)]
        pub struct $name {
            pub compiler: Compiler,
            pub target: TargetSelection,
        }

        impl Step for $name {
            type Output = ToolBuildResult;

            fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
                run.path($path)
            }

            fn make_run(run: RunConfig<'_>) {
                run.builder.ensure($name {
                    // snapshot compiler
                    compiler: run.builder.compiler(0, run.builder.config.build),
                    target: run.target,
                });
            }

            #[cfg_attr(
                feature = "tracing",
                instrument(
                    level = "debug",
                    name = $tool_name,
                    skip_all,
                ),
            )]
            fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
                $(
                    for submodule in $submodules {
                        builder.require_submodule(submodule, None);
                    }
                )*

                builder.ensure(ToolBuild {
                    compiler: self.compiler,
                    target: self.target,
                    tool: $tool_name,
                    mode: if false $(|| $unstable)* {
                        // use in-tree libraries for unstable features
                        Mode::ToolStd
                    } else {
                        Mode::ToolBootstrap
                    },
                    path: $path,
                    source_type: if false $(|| $external)* {
                        SourceType::Submodule
                    } else {
                        SourceType::InTree
                    },
                    extra_features: vec![],
                    allow_features: concat!($($allow_features)*),
                    cargo_args: vec![],
                    artifact_kind: if false $(|| $artifact_kind == ToolArtifactKind::Library)* {
                        ToolArtifactKind::Library
                    } else {
                        ToolArtifactKind::Binary
                    }
                })
            }
        }
        )+
    }
}

bootstrap_tool!(
    // This is marked as an external tool because it includes dependencies
    // from submodules. Trying to keep the lints in sync between all the repos
    // is a bit of a pain. Unfortunately it means the rustbook source itself
    // doesn't deny warnings, but it is a relatively small piece of code.
    Rustbook, "src/tools/rustbook", "rustbook", is_external_tool = true, submodules = SUBMODULES_FOR_RUSTBOOK;
    UnstableBookGen, "src/tools/unstable-book-gen", "unstable-book-gen";
    Tidy, "src/tools/tidy", "tidy";
    Linkchecker, "src/tools/linkchecker", "linkchecker";
    CargoTest, "src/tools/cargotest", "cargotest";
    Compiletest, "src/tools/compiletest", "compiletest", is_unstable_tool = true, allow_features = "test";
    BuildManifest, "src/tools/build-manifest", "build-manifest";
    RemoteTestClient, "src/tools/remote-test-client", "remote-test-client";
    RustInstaller, "src/tools/rust-installer", "rust-installer";
    RustdocTheme, "src/tools/rustdoc-themes", "rustdoc-themes";
    LintDocs, "src/tools/lint-docs", "lint-docs";
    JsonDocCk, "src/tools/jsondocck", "jsondocck";
    JsonDocLint, "src/tools/jsondoclint", "jsondoclint";
    HtmlChecker, "src/tools/html-checker", "html-checker";
    BumpStage0, "src/tools/bump-stage0", "bump-stage0";
    ReplaceVersionPlaceholder, "src/tools/replace-version-placeholder", "replace-version-placeholder";
    CollectLicenseMetadata, "src/tools/collect-license-metadata", "collect-license-metadata";
    GenerateCopyright, "src/tools/generate-copyright", "generate-copyright";
    SuggestTests, "src/tools/suggest-tests", "suggest-tests";
    GenerateWindowsSys, "src/tools/generate-windows-sys", "generate-windows-sys";
    RustdocGUITest, "src/tools/rustdoc-gui-test", "rustdoc-gui-test", is_unstable_tool = true, allow_features = "test";
    CoverageDump, "src/tools/coverage-dump", "coverage-dump";
    WasmComponentLd, "src/tools/wasm-component-ld", "wasm-component-ld", is_unstable_tool = true, allow_features = "min_specialization";
    UnicodeTableGenerator, "src/tools/unicode-table-generator", "unicode-table-generator";
    FeaturesStatusDump, "src/tools/features-status-dump", "features-status-dump";
    OptimizedDist, "src/tools/opt-dist", "opt-dist", submodules = &["src/tools/rustc-perf"];
    RunMakeSupport, "src/tools/run-make-support", "run_make_support", artifact_kind = ToolArtifactKind::Library;
);

/// These are the submodules that are required for rustbook to work due to
/// depending on mdbook plugins.
pub static SUBMODULES_FOR_RUSTBOOK: &[&str] = &["src/doc/book", "src/doc/reference"];

/// The [rustc-perf](https://github.com/rust-lang/rustc-perf) benchmark suite, which is added
/// as a submodule at `src/tools/rustc-perf`.
#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct RustcPerf {
    pub compiler: Compiler,
    pub target: TargetSelection,
}

impl Step for RustcPerf {
    /// Path to the built `collector` binary.
    type Output = ToolBuildResult;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.path("src/tools/rustc-perf")
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder.ensure(RustcPerf {
            compiler: run.builder.compiler(0, run.builder.config.build),
            target: run.target,
        });
    }

    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        // We need to ensure the rustc-perf submodule is initialized.
        builder.require_submodule("src/tools/rustc-perf", None);

        let tool = ToolBuild {
            compiler: self.compiler,
            target: self.target,
            tool: "collector",
            mode: Mode::ToolBootstrap,
            path: "src/tools/rustc-perf",
            source_type: SourceType::Submodule,
            extra_features: Vec::new(),
            allow_features: "",
            // Only build the collector package, which is used for benchmarking through
            // a CLI.
            cargo_args: vec!["-p".to_string(), "collector".to_string()],
            artifact_kind: ToolArtifactKind::Binary,
        };
        let res = builder.ensure(tool.clone());
        // We also need to symlink the `rustc-fake` binary to the corresponding directory,
        // because `collector` expects it in the same directory.
        copy_link_tool_bin(builder, tool.compiler, tool.target, tool.mode, "rustc-fake");

        res
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
pub struct ErrorIndex {
    pub compiler: Compiler,
}

impl ErrorIndex {
    pub fn command(builder: &Builder<'_>) -> BootstrapCommand {
        // Error-index-generator links with the rustdoc library, so we need to add `rustc_lib_paths`
        // for rustc_private and libLLVM.so, and `sysroot_lib` for libstd, etc.
        let host = builder.config.build;
        let compiler = builder.compiler_for(builder.top_stage, host, host);
        let mut cmd = command(builder.ensure(ErrorIndex { compiler }).tool_path);
        let mut dylib_paths = builder.rustc_lib_paths(compiler);
        dylib_paths.push(PathBuf::from(&builder.sysroot_target_libdir(compiler, compiler.host)));
        add_dylib_path(dylib_paths, &mut cmd);
        cmd
    }
}

impl Step for ErrorIndex {
    type Output = ToolBuildResult;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.path("src/tools/error_index_generator")
    }

    fn make_run(run: RunConfig<'_>) {
        // NOTE: This `make_run` isn't used in normal situations, only if you
        // manually build the tool with `x.py build
        // src/tools/error-index-generator` which almost nobody does.
        // Normally, `x.py test` or `x.py doc` will use the
        // `ErrorIndex::command` function instead.
        let compiler = run.builder.compiler(run.builder.top_stage, run.builder.config.build);
        run.builder.ensure(ErrorIndex { compiler });
    }

    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        builder.ensure(ToolBuild {
            compiler: self.compiler,
            target: self.compiler.host,
            tool: "error_index_generator",
            mode: Mode::ToolRustc,
            path: "src/tools/error_index_generator",
            source_type: SourceType::InTree,
            extra_features: Vec::new(),
            allow_features: "",
            cargo_args: Vec::new(),
            artifact_kind: ToolArtifactKind::Binary,
        })
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct RemoteTestServer {
    pub compiler: Compiler,
    pub target: TargetSelection,
}

impl Step for RemoteTestServer {
    type Output = ToolBuildResult;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.path("src/tools/remote-test-server")
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder.ensure(RemoteTestServer {
            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
            target: run.target,
        });
    }

    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        builder.ensure(ToolBuild {
            compiler: self.compiler,
            target: self.target,
            tool: "remote-test-server",
            mode: Mode::ToolStd,
            path: "src/tools/remote-test-server",
            source_type: SourceType::InTree,
            extra_features: Vec::new(),
            allow_features: "",
            cargo_args: Vec::new(),
            artifact_kind: ToolArtifactKind::Binary,
        })
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
pub struct Rustdoc {
    /// This should only ever be 0 or 2.
    /// We sometimes want to reference the "bootstrap" rustdoc, which is why this option is here.
    pub compiler: Compiler,
}

impl Step for Rustdoc {
    type Output = ToolBuildResult;
    const DEFAULT: bool = true;
    const ONLY_HOSTS: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.path("src/tools/rustdoc").path("src/librustdoc")
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder
            .ensure(Rustdoc { compiler: run.builder.compiler(run.builder.top_stage, run.target) });
    }

    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        let target_compiler = self.compiler;
        let target = target_compiler.host;

        if target_compiler.stage == 0 {
            if !target_compiler.is_snapshot(builder) {
                panic!("rustdoc in stage 0 must be snapshot rustdoc");
            }

            return ToolBuildResult {
                tool_path: builder.initial_rustdoc.clone(),
                build_compiler: target_compiler,
                target_compiler,
            };
        }

        let bin_rustdoc = || {
            let sysroot = builder.sysroot(target_compiler);
            let bindir = sysroot.join("bin");
            t!(fs::create_dir_all(&bindir));
            let bin_rustdoc = bindir.join(exe("rustdoc", target_compiler.host));
            let _ = fs::remove_file(&bin_rustdoc);
            bin_rustdoc
        };

        // If CI rustc is enabled and we haven't modified the rustdoc sources,
        // use the precompiled rustdoc from CI rustc's sysroot to speed up bootstrapping.
        if builder.download_rustc()
            && target_compiler.stage > 0
            && builder.rust_info().is_managed_git_subrepository()
        {
            let files_to_track = &["src/librustdoc", "src/tools/rustdoc"];

            // Check if unchanged
            if builder.config.last_modified_commit(files_to_track, "download-rustc", true).is_some()
            {
                let precompiled_rustdoc = builder
                    .config
                    .ci_rustc_dir()
                    .join("bin")
                    .join(exe("rustdoc", target_compiler.host));

                let bin_rustdoc = bin_rustdoc();
                builder.copy_link(&precompiled_rustdoc, &bin_rustdoc);

                return ToolBuildResult {
                    tool_path: bin_rustdoc,
                    build_compiler: target_compiler,
                    target_compiler,
                };
            }
        }

        // The presence of `target_compiler` ensures that the necessary libraries (codegen backends,
        // compiler libraries, ...) are built. Rustdoc does not require the presence of any
        // libraries within sysroot_libdir (i.e., rustlib), though doctests may want it (since
        // they'll be linked to those libraries). As such, don't explicitly `ensure` any additional
        // libraries here. The intuition here is that If we've built a compiler, we should be able
        // to build rustdoc.
        //
        let mut extra_features = Vec::new();
        if builder.config.jemalloc(target) {
            extra_features.push("jemalloc".to_string());
        }

        let ToolBuildResult { tool_path, build_compiler, target_compiler } =
            builder.ensure(ToolBuild {
                compiler: target_compiler,
                target,
                // Cargo adds a number of paths to the dylib search path on windows, which results in
                // the wrong rustdoc being executed. To avoid the conflicting rustdocs, we name the "tool"
                // rustdoc a different name.
                tool: "rustdoc_tool_binary",
                mode: Mode::ToolRustc,
                path: "src/tools/rustdoc",
                source_type: SourceType::InTree,
                extra_features,
                allow_features: "",
                cargo_args: Vec::new(),
                artifact_kind: ToolArtifactKind::Binary,
            });

        // don't create a stage0-sysroot/bin directory.
        if target_compiler.stage > 0 {
            if builder.config.rust_debuginfo_level_tools == DebuginfoLevel::None {
                // Due to LTO a lot of debug info from C++ dependencies such as jemalloc can make it into
                // our final binaries
                compile::strip_debug(builder, target, &tool_path);
            }
            let bin_rustdoc = bin_rustdoc();
            builder.copy_link(&tool_path, &bin_rustdoc);
            ToolBuildResult { tool_path: bin_rustdoc, build_compiler, target_compiler }
        } else {
            ToolBuildResult { tool_path, build_compiler, target_compiler }
        }
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct Cargo {
    pub compiler: Compiler,
    pub target: TargetSelection,
}

impl Step for Cargo {
    type Output = ToolBuildResult;
    const DEFAULT: bool = true;
    const ONLY_HOSTS: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        let builder = run.builder;
        run.path("src/tools/cargo").default_condition(builder.tool_enabled("cargo"))
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder.ensure(Cargo {
            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
            target: run.target,
        });
    }

    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        builder.build.require_submodule("src/tools/cargo", None);

        builder.ensure(ToolBuild {
            compiler: self.compiler,
            target: self.target,
            tool: "cargo",
            mode: Mode::ToolRustc,
            path: "src/tools/cargo",
            source_type: SourceType::Submodule,
            extra_features: Vec::new(),
            allow_features: "",
            cargo_args: Vec::new(),
            artifact_kind: ToolArtifactKind::Binary,
        })
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct LldWrapper {
    pub build_compiler: Compiler,
    pub target_compiler: Compiler,
}

impl Step for LldWrapper {
    type Output = ToolBuildResult;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.never()
    }

    #[cfg_attr(
        feature = "tracing",
        instrument(
            level = "debug",
            name = "LldWrapper::run",
            skip_all,
            fields(build_compiler = ?self.build_compiler, target_compiler = ?self.target_compiler),
        ),
    )]

    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        if builder.config.dry_run() {
            return ToolBuildResult {
                tool_path: Default::default(),
                build_compiler: self.build_compiler,
                target_compiler: self.target_compiler,
            };
        }

        let target = self.target_compiler.host;

        let tool_result = builder.ensure(ToolBuild {
            compiler: self.build_compiler,
            target,
            tool: "lld-wrapper",
            mode: Mode::ToolStd,
            path: "src/tools/lld-wrapper",
            source_type: SourceType::InTree,
            extra_features: Vec::new(),
            allow_features: "",
            cargo_args: Vec::new(),
            artifact_kind: ToolArtifactKind::Binary,
        });

        let libdir_bin = builder.sysroot_target_bindir(self.target_compiler, target);
        t!(fs::create_dir_all(&libdir_bin));

        let lld_install = builder.ensure(llvm::Lld { target });
        let src_exe = exe("lld", target);
        let dst_exe = exe("rust-lld", target);

        builder.copy_link(&lld_install.join("bin").join(src_exe), &libdir_bin.join(dst_exe));
        let self_contained_lld_dir = libdir_bin.join("gcc-ld");
        t!(fs::create_dir_all(&self_contained_lld_dir));

        for name in crate::LLD_FILE_NAMES {
            builder
                .copy_link(&tool_result.tool_path, &self_contained_lld_dir.join(exe(name, target)));
        }

        tool_result
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct RustAnalyzer {
    pub compiler: Compiler,
    pub target: TargetSelection,
}

impl RustAnalyzer {
    pub const ALLOW_FEATURES: &'static str = "rustc_private,proc_macro_internals,proc_macro_diagnostic,proc_macro_span,proc_macro_span_shrink,proc_macro_def_site";
}

impl Step for RustAnalyzer {
    type Output = ToolBuildResult;
    const DEFAULT: bool = true;
    const ONLY_HOSTS: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        let builder = run.builder;
        run.path("src/tools/rust-analyzer").default_condition(builder.tool_enabled("rust-analyzer"))
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder.ensure(RustAnalyzer {
            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
            target: run.target,
        });
    }

    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        builder.ensure(ToolBuild {
            compiler: self.compiler,
            target: self.target,
            tool: "rust-analyzer",
            mode: Mode::ToolRustc,
            path: "src/tools/rust-analyzer",
            extra_features: vec!["in-rust-tree".to_owned()],
            source_type: SourceType::InTree,
            allow_features: RustAnalyzer::ALLOW_FEATURES,
            cargo_args: Vec::new(),
            artifact_kind: ToolArtifactKind::Binary,
        })
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct RustAnalyzerProcMacroSrv {
    pub compiler: Compiler,
    pub target: TargetSelection,
}

impl Step for RustAnalyzerProcMacroSrv {
    type Output = Option<ToolBuildResult>;
    const DEFAULT: bool = true;
    const ONLY_HOSTS: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        let builder = run.builder;
        // Allow building `rust-analyzer-proc-macro-srv` both as part of the `rust-analyzer` and as a stand-alone tool.
        run.path("src/tools/rust-analyzer")
            .path("src/tools/rust-analyzer/crates/proc-macro-srv-cli")
            .default_condition(
                builder.tool_enabled("rust-analyzer")
                    || builder.tool_enabled("rust-analyzer-proc-macro-srv"),
            )
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder.ensure(RustAnalyzerProcMacroSrv {
            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
            target: run.target,
        });
    }

    fn run(self, builder: &Builder<'_>) -> Option<ToolBuildResult> {
        let tool_result = builder.ensure(ToolBuild {
            compiler: self.compiler,
            target: self.target,
            tool: "rust-analyzer-proc-macro-srv",
            mode: Mode::ToolRustc,
            path: "src/tools/rust-analyzer/crates/proc-macro-srv-cli",
            extra_features: vec!["in-rust-tree".to_owned()],
            source_type: SourceType::InTree,
            allow_features: RustAnalyzer::ALLOW_FEATURES,
            cargo_args: Vec::new(),
            artifact_kind: ToolArtifactKind::Binary,
        });

        // Copy `rust-analyzer-proc-macro-srv` to `<sysroot>/libexec/`
        // so that r-a can use it.
        let libexec_path = builder.sysroot(self.compiler).join("libexec");
        t!(fs::create_dir_all(&libexec_path));
        builder
            .copy_link(&tool_result.tool_path, &libexec_path.join("rust-analyzer-proc-macro-srv"));

        Some(tool_result)
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct LlvmBitcodeLinker {
    pub compiler: Compiler,
    pub target: TargetSelection,
    pub extra_features: Vec<String>,
}

impl Step for LlvmBitcodeLinker {
    type Output = ToolBuildResult;
    const DEFAULT: bool = true;
    const ONLY_HOSTS: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        let builder = run.builder;
        run.path("src/tools/llvm-bitcode-linker")
            .default_condition(builder.tool_enabled("llvm-bitcode-linker"))
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder.ensure(LlvmBitcodeLinker {
            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
            extra_features: Vec::new(),
            target: run.target,
        });
    }

    #[cfg_attr(
        feature = "tracing",
        instrument(level = "debug", name = "LlvmBitcodeLinker::run", skip_all)
    )]
    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        let tool_result = builder.ensure(ToolBuild {
            compiler: self.compiler,
            target: self.target,
            tool: "llvm-bitcode-linker",
            mode: Mode::ToolRustc,
            path: "src/tools/llvm-bitcode-linker",
            source_type: SourceType::InTree,
            extra_features: self.extra_features,
            allow_features: "",
            cargo_args: Vec::new(),
            artifact_kind: ToolArtifactKind::Binary,
        });

        if tool_result.target_compiler.stage > 0 {
            let bindir_self_contained = builder
                .sysroot(tool_result.target_compiler)
                .join(format!("lib/rustlib/{}/bin/self-contained", self.target.triple));
            t!(fs::create_dir_all(&bindir_self_contained));
            let bin_destination = bindir_self_contained
                .join(exe("llvm-bitcode-linker", tool_result.target_compiler.host));
            builder.copy_link(&tool_result.tool_path, &bin_destination);
            ToolBuildResult {
                tool_path: bin_destination,
                build_compiler: tool_result.build_compiler,
                target_compiler: tool_result.target_compiler,
            }
        } else {
            tool_result
        }
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct LibcxxVersionTool {
    pub target: TargetSelection,
}

#[expect(dead_code)]
#[derive(Debug, Clone)]
pub enum LibcxxVersion {
    Gnu(usize),
    Llvm(usize),
}

impl Step for LibcxxVersionTool {
    type Output = LibcxxVersion;
    const DEFAULT: bool = false;
    const ONLY_HOSTS: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.never()
    }

    fn run(self, builder: &Builder<'_>) -> LibcxxVersion {
        let out_dir = builder.out.join(self.target.to_string()).join("libcxx-version");
        let executable = out_dir.join(exe("libcxx-version", self.target));

        // This is a sanity-check specific step, which means it is frequently called (when using
        // CI LLVM), and compiling `src/tools/libcxx-version/main.cpp` at the beginning of the bootstrap
        // invocation adds a fair amount of overhead to the process (see https://github.com/rust-lang/rust/issues/126423).
        // Therefore, we want to avoid recompiling this file unnecessarily.
        if !executable.exists() {
            if !out_dir.exists() {
                t!(fs::create_dir_all(&out_dir));
            }

            let compiler = builder.cxx(self.target).unwrap();
            let mut cmd = command(compiler);

            cmd.arg("-o")
                .arg(&executable)
                .arg(builder.src.join("src/tools/libcxx-version/main.cpp"));

            cmd.run(builder);

            if !executable.exists() {
                panic!("Something went wrong. {} is not present", executable.display());
            }
        }

        let version_output = command(executable).run_capture_stdout(builder).stdout();

        let version_str = version_output.split_once("version:").unwrap().1;
        let version = version_str.trim().parse::<usize>().unwrap();

        if version_output.starts_with("libstdc++") {
            LibcxxVersion::Gnu(version)
        } else if version_output.starts_with("libc++") {
            LibcxxVersion::Llvm(version)
        } else {
            panic!("Coudln't recognize the standard library version.");
        }
    }
}

macro_rules! tool_extended {
    (
        $name:ident {
            path: $path:expr,
            tool_name: $tool_name:expr,
            stable: $stable:expr
            $( , add_bins_to_sysroot: $add_bins_to_sysroot:expr )?
            $( , )?
        }
    ) => {
        #[derive(Debug, Clone, Hash, PartialEq, Eq)]
        pub struct $name {
            pub compiler: Compiler,
            pub target: TargetSelection,
        }

        impl Step for $name {
            type Output = ToolBuildResult;
            const DEFAULT: bool = true; // Overridden by `should_run_tool_build_step`
            const ONLY_HOSTS: bool = true;

            fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
                should_run_tool_build_step(
                    run,
                    $tool_name,
                    $path,
                    $stable,
                )
            }

            fn make_run(run: RunConfig<'_>) {
                run.builder.ensure($name {
                    compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.build),
                    target: run.target,
                });
            }

            fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
                let Self { compiler, target } = self;
                run_tool_build_step(
                    builder,
                    compiler,
                    target,
                    $tool_name,
                    $path,
                    None $( .or(Some(&$add_bins_to_sysroot)) )?,
                )
            }
        }
    }
}

fn should_run_tool_build_step<'a>(
    run: ShouldRun<'a>,
    tool_name: &'static str,
    path: &'static str,
    stable: bool,
) -> ShouldRun<'a> {
    let builder = run.builder;
    run.path(path).default_condition(
        builder.config.extended
            && builder.config.tools.as_ref().map_or(
                // By default, on nightly/dev enable all tools, else only
                // build stable tools.
                stable || builder.build.unstable_features(),
                // If `tools` is set, search list for this tool.
                |tools| {
                    tools.iter().any(|tool| match tool.as_ref() {
                        "clippy" => tool_name == "clippy-driver",
                        x => tool_name == x,
                    })
                },
            ),
    )
}

fn run_tool_build_step(
    builder: &Builder<'_>,
    compiler: Compiler,
    target: TargetSelection,
    tool_name: &'static str,
    path: &'static str,
    add_bins_to_sysroot: Option<&[&str]>,
) -> ToolBuildResult {
    let ToolBuildResult { tool_path, build_compiler, target_compiler } =
        builder.ensure(ToolBuild {
            compiler,
            target,
            tool: tool_name,
            mode: Mode::ToolRustc,
            path,
            extra_features: vec![],
            source_type: SourceType::InTree,
            allow_features: "",
            cargo_args: vec![],
            artifact_kind: ToolArtifactKind::Binary,
        });

    // FIXME: This should just be an if-let-chain, but those are unstable.
    if let Some(add_bins_to_sysroot) =
        add_bins_to_sysroot.filter(|bins| !bins.is_empty() && target_compiler.stage > 0)
    {
        let bindir = builder.sysroot(target_compiler).join("bin");
        t!(fs::create_dir_all(&bindir));

        for add_bin in add_bins_to_sysroot {
            let bin_destination = bindir.join(exe(add_bin, target_compiler.host));
            builder.copy_link(&tool_path, &bin_destination);
        }

        // Return a path into the bin dir.
        let path = bindir.join(exe(tool_name, target_compiler.host));
        ToolBuildResult { tool_path: path, build_compiler, target_compiler }
    } else {
        ToolBuildResult { tool_path, build_compiler, target_compiler }
    }
}

tool_extended!(Cargofmt {
    path: "src/tools/rustfmt",
    tool_name: "cargo-fmt",
    stable: true,
    add_bins_to_sysroot: ["cargo-fmt"]
});
tool_extended!(CargoClippy {
    path: "src/tools/clippy",
    tool_name: "cargo-clippy",
    stable: true,
    add_bins_to_sysroot: ["cargo-clippy"]
});
tool_extended!(Clippy {
    path: "src/tools/clippy",
    tool_name: "clippy-driver",
    stable: true,
    add_bins_to_sysroot: ["clippy-driver"]
});
tool_extended!(Miri {
    path: "src/tools/miri",
    tool_name: "miri",
    stable: false,
    add_bins_to_sysroot: ["miri"]
});
tool_extended!(CargoMiri {
    path: "src/tools/miri/cargo-miri",
    tool_name: "cargo-miri",
    stable: false,
    add_bins_to_sysroot: ["cargo-miri"]
});
tool_extended!(Rustfmt {
    path: "src/tools/rustfmt",
    tool_name: "rustfmt",
    stable: true,
    add_bins_to_sysroot: ["rustfmt"]
});

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct TestFloatParse {
    pub host: TargetSelection,
}

impl Step for TestFloatParse {
    type Output = ToolBuildResult;
    const ONLY_HOSTS: bool = true;
    const DEFAULT: bool = false;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.path("src/etc/test-float-parse")
    }

    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
        let bootstrap_host = builder.config.build;
        let compiler = builder.compiler(builder.top_stage, bootstrap_host);

        builder.ensure(ToolBuild {
            compiler,
            target: bootstrap_host,
            tool: "test-float-parse",
            mode: Mode::ToolStd,
            path: "src/etc/test-float-parse",
            source_type: SourceType::InTree,
            extra_features: Vec::new(),
            allow_features: "",
            cargo_args: Vec::new(),
            artifact_kind: ToolArtifactKind::Binary,
        })
    }
}

impl Builder<'_> {
    /// Gets a `BootstrapCommand` which is ready to run `tool` in `stage` built for
    /// `host`.
    pub fn tool_cmd(&self, tool: Tool) -> BootstrapCommand {
        let mut cmd = command(self.tool_exe(tool));
        let compiler = self.compiler(0, self.config.build);
        let host = &compiler.host;
        // Prepares the `cmd` provided to be able to run the `compiler` provided.
        //
        // Notably this munges the dynamic library lookup path to point to the
        // right location to run `compiler`.
        let mut lib_paths: Vec<PathBuf> = vec![
            self.build.rustc_snapshot_libdir(),
            self.cargo_out(compiler, Mode::ToolBootstrap, *host).join("deps"),
        ];

        // On MSVC a tool may invoke a C compiler (e.g., compiletest in run-make
        // mode) and that C compiler may need some extra PATH modification. Do
        // so here.
        if compiler.host.is_msvc() {
            let curpaths = env::var_os("PATH").unwrap_or_default();
            let curpaths = env::split_paths(&curpaths).collect::<Vec<_>>();
            for (k, v) in self.cc.borrow()[&compiler.host].env() {
                if k != "PATH" {
                    continue;
                }
                for path in env::split_paths(v) {
                    if !curpaths.contains(&path) {
                        lib_paths.push(path);
                    }
                }
            }
        }

        add_dylib_path(lib_paths, &mut cmd);

        // Provide a RUSTC for this command to use.
        cmd.env("RUSTC", &self.initial_rustc);

        cmd
    }
}