Auto merge of #144303 - Kobzol:bootstrap-tool-cleanup, r=jieyouxu

Consolidate staging for `rustc_private` tools

This PR continues bootstrap refactoring, this time by consolidating staging for `Mode::ToolRustc` tools. This refactoring was in the critical path of refactoring `test`/`dist`/`clippy`/`doc` steps, and getting rid of the rmeta/rlib sysroot copy, because tools are pervasive and they are being used for a lot of things in bootstrap.

The main idea is to explicitly model the fact that a stage N `Mode::ToolRustc` tool always works with two different compilers:
- Stage N-1 rustc (`build_compiler`) builds stage N rustc (`target_compiler`)
- Rlib artifacts from stage N rustc are copied to the sysroot of stage N-1 rustc
- Stage N-1 rustc builds the (stage N) tool itself, the tool links to the rlib artifacts of the stage N rustc

Before, the code often used `compiler`, which meant sometimes the build compiler, sometimes the target compiler, and sometimes neither (looking at you, `download-rustc`). This is especially annoying when you get to a situation where you have an install step that invokes a dist step that invokes a tool build step, where *some* compiler is being propagated through, without it being clear what does that compiler represent. This refactoring hopefully makes that clearer and more explicit. It also gets rid of a few `builder.ensure(Rustc(...))` calls within bootstrap, which is always nice.

`Rustdoc` needs to be handled a bit specially, because it acts as a compiler itself, I documented that in the changes.

It wasn't practical to do these refactorings in multiple PRs, so I did it all in one PR. The meat of the change is 9ee6d1c1ed112c3dcfb5684b33772b136df0dca3.

I tested manually that `x build rustdoc` and `x build miri` still works even with `download-rustc`, although I cannot promise any extra support for `download-rustc`, IMO we will just have to reimplement it from scratch in a different way.

As usually, I did some drive-by refactorings to bootstrap, trying to document and clarify things, add more step metadata and tests.

Since these changes broke Cargo, which was incorrectly using `Mode::ToolRustc`, I also changed cargo to `ToolTarget` in this PR.

Best reviewed commit-by-commit (note that I renamed `link_compiler` to `target_compiler`, in accordance to the rest of bootstrap, in the last commit).

r? `@jieyouxu`

try-job: x86_64-gnu-aux
try-job: x86_64-msvc-ext1

12 files changed, 744 insertions, 453 deletions

diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index 59541bf12de..95707e37018 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -19,7 +19,7 @@ use serde_derive::Deserialize;
 use tracing::{instrument, span};
 
 use crate::core::build_steps::gcc::{Gcc, add_cg_gcc_cargo_flags};
-use crate::core::build_steps::tool::{SourceType, copy_lld_artifacts};
+use crate::core::build_steps::tool::{RustcPrivateCompilers, SourceType, copy_lld_artifacts};
 use crate::core::build_steps::{dist, llvm};
 use crate::core::builder;
 use crate::core::builder::{
@@ -1131,7 +1131,7 @@ impl Step for Rustc {
             cargo.env("RUSTC_BOLT_LINK_FLAGS", "1");
         }
 
-        let _guard = builder.msg_sysroot_tool(
+        let _guard = builder.msg_rustc_tool(
             Kind::Build,
             build_compiler.stage,
             format_args!("compiler artifacts{}", crate_description(&self.crates)),
@@ -1544,9 +1544,8 @@ impl Step for RustcLink {
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct CodegenBackend {
-    pub target: TargetSelection,
-    pub compiler: Compiler,
-    pub backend: CodegenBackendKind,
+    compilers: RustcPrivateCompilers,
+    backend: CodegenBackendKind,
 }
 
 fn needs_codegen_config(run: &RunConfig<'_>) -> bool {
@@ -1610,8 +1609,11 @@ impl Step for CodegenBackend {
             }
 
             run.builder.ensure(CodegenBackend {
-                target: run.target,
-                compiler: run.builder.compiler(run.builder.top_stage, run.build_triple()),
+                compilers: RustcPrivateCompilers::new(
+                    run.builder,
+                    run.builder.top_stage,
+                    run.target,
+                ),
                 backend: backend.clone(),
             });
         }
@@ -1624,20 +1626,17 @@ impl Step for CodegenBackend {
             name = "CodegenBackend::run",
             skip_all,
             fields(
-                compiler = ?self.compiler,
-                target = ?self.target,
-                backend = ?self.target,
+                compilers = ?self.compilers,
+                backend = ?self.backend,
             ),
         ),
     )]
     fn run(self, builder: &Builder<'_>) {
-        let compiler = self.compiler;
-        let target = self.target;
         let backend = self.backend;
+        let target = self.compilers.target();
+        let build_compiler = self.compilers.build_compiler();
 
-        builder.ensure(Rustc::new(compiler, target));
-
-        if builder.config.keep_stage.contains(&compiler.stage) {
+        if builder.config.keep_stage.contains(&build_compiler.stage) {
             trace!("`keep-stage` requested");
             builder.info(
                 "WARNING: Using a potentially old codegen backend. \
@@ -1648,17 +1647,11 @@ impl Step for CodegenBackend {
             return;
         }
 
-        let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
-        if compiler_to_use != compiler {
-            builder.ensure(CodegenBackend { compiler: compiler_to_use, target, backend });
-            return;
-        }
-
-        let out_dir = builder.cargo_out(compiler, Mode::Codegen, target);
+        let out_dir = builder.cargo_out(build_compiler, Mode::Codegen, target);
 
         let mut cargo = builder::Cargo::new(
             builder,
-            compiler,
+            build_compiler,
             Mode::Codegen,
             SourceType::InTree,
             target,
@@ -1679,8 +1672,13 @@ impl Step for CodegenBackend {
 
         let tmp_stamp = BuildStamp::new(&out_dir).with_prefix("tmp");
 
-        let _guard =
-            builder.msg_build(compiler, format_args!("codegen backend {}", backend.name()), target);
+        let _guard = builder.msg_rustc_tool(
+            Kind::Build,
+            build_compiler.stage,
+            format_args!("codegen backend {}", backend.name()),
+            build_compiler.host,
+            target,
+        );
         let files = run_cargo(builder, cargo, vec![], &tmp_stamp, vec![], false, false);
         if builder.config.dry_run() {
             return;
@@ -1700,10 +1698,17 @@ impl Step for CodegenBackend {
                 f.display()
             );
         }
-        let stamp = build_stamp::codegen_backend_stamp(builder, compiler, target, &backend);
+        let stamp = build_stamp::codegen_backend_stamp(builder, build_compiler, target, &backend);
         let codegen_backend = codegen_backend.to_str().unwrap();
         t!(stamp.add_stamp(codegen_backend).write());
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(
+            StepMetadata::build(&self.backend.crate_name(), self.compilers.target())
+                .built_by(self.compilers.build_compiler()),
+        )
+    }
 }
 
 /// Creates the `codegen-backends` folder for a compiler that's about to be
@@ -2190,8 +2195,10 @@ impl Step for Assemble {
                 continue;
             }
             builder.ensure(CodegenBackend {
-                compiler: build_compiler,
-                target: target_compiler.host,
+                compilers: RustcPrivateCompilers::from_build_and_target_compiler(
+                    build_compiler,
+                    target_compiler,
+                ),
                 backend: backend.clone(),
             });
         }
diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index 4699813abf4..0465a071159 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -20,7 +20,7 @@ use object::read::archive::ArchiveFile;
 use tracing::instrument;
 
 use crate::core::build_steps::doc::DocumentationFormat;
-use crate::core::build_steps::tool::{self, Tool};
+use crate::core::build_steps::tool::{self, RustcPrivateCompilers, Tool};
 use crate::core::build_steps::vendor::{VENDOR_DIR, Vendor};
 use crate::core::build_steps::{compile, llvm};
 use crate::core::builder::{Builder, Kind, RunConfig, ShouldRun, Step, StepMetadata};
@@ -425,19 +425,20 @@ impl Step for Rustc {
                 .as_ref()
                 .is_none_or(|tools| tools.iter().any(|tool| tool == "rustdoc"))
             {
-                let rustdoc = builder.rustdoc(compiler);
+                let rustdoc = builder.rustdoc_for_compiler(compiler);
                 builder.install(&rustdoc, &image.join("bin"), FileType::Executable);
             }
 
             let ra_proc_macro_srv_compiler =
                 builder.compiler_for(compiler.stage, builder.config.host_target, compiler.host);
-            builder.ensure(compile::Rustc::new(ra_proc_macro_srv_compiler, compiler.host));
+            let compilers = RustcPrivateCompilers::from_build_compiler(
+                builder,
+                ra_proc_macro_srv_compiler,
+                compiler.host,
+            );
 
             if let Some(ra_proc_macro_srv) = builder.ensure_if_default(
-                tool::RustAnalyzerProcMacroSrv {
-                    compiler: ra_proc_macro_srv_compiler,
-                    target: compiler.host,
-                },
+                tool::RustAnalyzerProcMacroSrv::from_compilers(compilers),
                 builder.kind,
             ) {
                 let dst = image.join("libexec");
@@ -1172,7 +1173,7 @@ impl Step for PlainSourceTarball {
 
 #[derive(Debug, PartialOrd, Ord, Clone, Hash, PartialEq, Eq)]
 pub struct Cargo {
-    pub compiler: Compiler,
+    pub build_compiler: Compiler,
     pub target: TargetSelection,
 }
 
@@ -1188,7 +1189,7 @@ impl Step for Cargo {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(Cargo {
-            compiler: run.builder.compiler_for(
+            build_compiler: run.builder.compiler_for(
                 run.builder.top_stage,
                 run.builder.config.host_target,
                 run.target,
@@ -1198,12 +1199,10 @@ impl Step for Cargo {
     }
 
     fn run(self, builder: &Builder<'_>) -> Option<GeneratedTarball> {
-        let compiler = self.compiler;
+        let build_compiler = self.build_compiler;
         let target = self.target;
 
-        builder.ensure(compile::Rustc::new(compiler, target));
-
-        let cargo = builder.ensure(tool::Cargo { compiler, target });
+        let cargo = builder.ensure(tool::Cargo::from_build_compiler(build_compiler, target));
         let src = builder.src.join("src/tools/cargo");
         let etc = src.join("src/etc");
 
@@ -1228,7 +1227,7 @@ impl Step for Cargo {
 
 #[derive(Debug, PartialOrd, Ord, Clone, Hash, PartialEq, Eq)]
 pub struct RustAnalyzer {
-    pub compiler: Compiler,
+    pub build_compiler: Compiler,
     pub target: TargetSelection,
 }
 
@@ -1244,7 +1243,7 @@ impl Step for RustAnalyzer {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(RustAnalyzer {
-            compiler: run.builder.compiler_for(
+            build_compiler: run.builder.compiler_for(
                 run.builder.top_stage,
                 run.builder.config.host_target,
                 run.target,
@@ -1254,12 +1253,11 @@ impl Step for RustAnalyzer {
     }
 
     fn run(self, builder: &Builder<'_>) -> Option<GeneratedTarball> {
-        let compiler = self.compiler;
         let target = self.target;
+        let compilers =
+            RustcPrivateCompilers::from_build_compiler(builder, self.build_compiler, self.target);
 
-        builder.ensure(compile::Rustc::new(compiler, target));
-
-        let rust_analyzer = builder.ensure(tool::RustAnalyzer { compiler, target });
+        let rust_analyzer = builder.ensure(tool::RustAnalyzer::from_compilers(compilers));
 
         let mut tarball = Tarball::new(builder, "rust-analyzer", &target.triple);
         tarball.set_overlay(OverlayKind::RustAnalyzer);
@@ -1270,9 +1268,9 @@ impl Step for RustAnalyzer {
     }
 }
 
-#[derive(Debug, PartialOrd, Ord, Clone, Hash, PartialEq, Eq)]
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct Clippy {
-    pub compiler: Compiler,
+    pub build_compiler: Compiler,
     pub target: TargetSelection,
 }
 
@@ -1288,7 +1286,7 @@ impl Step for Clippy {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(Clippy {
-            compiler: run.builder.compiler_for(
+            build_compiler: run.builder.compiler_for(
                 run.builder.top_stage,
                 run.builder.config.host_target,
                 run.target,
@@ -1298,16 +1296,15 @@ impl Step for Clippy {
     }
 
     fn run(self, builder: &Builder<'_>) -> Option<GeneratedTarball> {
-        let compiler = self.compiler;
         let target = self.target;
-
-        builder.ensure(compile::Rustc::new(compiler, target));
+        let compilers =
+            RustcPrivateCompilers::from_build_compiler(builder, self.build_compiler, target);
 
         // Prepare the image directory
         // We expect clippy to build, because we've exited this step above if tool
         // state for clippy isn't testing.
-        let clippy = builder.ensure(tool::Clippy { compiler, target });
-        let cargoclippy = builder.ensure(tool::CargoClippy { compiler, target });
+        let clippy = builder.ensure(tool::Clippy::from_compilers(compilers));
+        let cargoclippy = builder.ensure(tool::CargoClippy::from_compilers(compilers));
 
         let mut tarball = Tarball::new(builder, "clippy", &target.triple);
         tarball.set_overlay(OverlayKind::Clippy);
@@ -1319,9 +1316,9 @@ impl Step for Clippy {
     }
 }
 
-#[derive(Debug, PartialOrd, Ord, Clone, Hash, PartialEq, Eq)]
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct Miri {
-    pub compiler: Compiler,
+    pub build_compiler: Compiler,
     pub target: TargetSelection,
 }
 
@@ -1337,7 +1334,7 @@ impl Step for Miri {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(Miri {
-            compiler: run.builder.compiler_for(
+            build_compiler: run.builder.compiler_for(
                 run.builder.top_stage,
                 run.builder.config.host_target,
                 run.target,
@@ -1354,15 +1351,12 @@ impl Step for Miri {
             return None;
         }
 
-        let compiler = self.compiler;
-        let target = self.target;
-
-        builder.ensure(compile::Rustc::new(compiler, target));
+        let compilers =
+            RustcPrivateCompilers::from_build_compiler(builder, self.build_compiler, self.target);
+        let miri = builder.ensure(tool::Miri::from_compilers(compilers));
+        let cargomiri = builder.ensure(tool::CargoMiri::from_compilers(compilers));
 
-        let miri = builder.ensure(tool::Miri { compiler, target });
-        let cargomiri = builder.ensure(tool::CargoMiri { compiler, target });
-
-        let mut tarball = Tarball::new(builder, "miri", &target.triple);
+        let mut tarball = Tarball::new(builder, "miri", &self.target.triple);
         tarball.set_overlay(OverlayKind::Miri);
         tarball.is_preview(true);
         tarball.add_file(&miri.tool_path, "bin", FileType::Executable);
@@ -1466,9 +1460,9 @@ impl Step for CodegenBackend {
     }
 }
 
-#[derive(Debug, PartialOrd, Ord, Clone, Hash, PartialEq, Eq)]
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct Rustfmt {
-    pub compiler: Compiler,
+    pub build_compiler: Compiler,
     pub target: TargetSelection,
 }
 
@@ -1484,7 +1478,7 @@ impl Step for Rustfmt {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(Rustfmt {
-            compiler: run.builder.compiler_for(
+            build_compiler: run.builder.compiler_for(
                 run.builder.top_stage,
                 run.builder.config.host_target,
                 run.target,
@@ -1494,14 +1488,13 @@ impl Step for Rustfmt {
     }
 
     fn run(self, builder: &Builder<'_>) -> Option<GeneratedTarball> {
-        let compiler = self.compiler;
-        let target = self.target;
+        let compilers =
+            RustcPrivateCompilers::from_build_compiler(builder, self.build_compiler, self.target);
 
-        builder.ensure(compile::Rustc::new(compiler, target));
+        let rustfmt = builder.ensure(tool::Rustfmt::from_compilers(compilers));
+        let cargofmt = builder.ensure(tool::Cargofmt::from_compilers(compilers));
 
-        let rustfmt = builder.ensure(tool::Rustfmt { compiler, target });
-        let cargofmt = builder.ensure(tool::Cargofmt { compiler, target });
-        let mut tarball = Tarball::new(builder, "rustfmt", &target.triple);
+        let mut tarball = Tarball::new(builder, "rustfmt", &self.target.triple);
         tarball.set_overlay(OverlayKind::Rustfmt);
         tarball.is_preview(true);
         tarball.add_file(&rustfmt.tool_path, "bin", FileType::Executable);
@@ -1548,7 +1541,7 @@ impl Step for Extended {
         let mut built_tools = HashSet::new();
         macro_rules! add_component {
             ($name:expr => $step:expr) => {
-                if let Some(tarball) = builder.ensure_if_default($step, Kind::Dist) {
+                if let Some(Some(tarball)) = builder.ensure_if_default($step, Kind::Dist) {
                     tarballs.push(tarball);
                     built_tools.insert($name);
                 }
@@ -1568,12 +1561,12 @@ impl Step for Extended {
 
         add_component!("rust-docs" => Docs { host: target });
         add_component!("rust-json-docs" => JsonDocs { host: target });
-        add_component!("cargo" => Cargo { compiler, target });
-        add_component!("rustfmt" => Rustfmt { compiler, target });
-        add_component!("rust-analyzer" => RustAnalyzer { compiler, target });
+        add_component!("cargo" => Cargo { build_compiler: compiler, target });
+        add_component!("rustfmt" => Rustfmt { build_compiler: compiler, target });
+        add_component!("rust-analyzer" => RustAnalyzer { build_compiler: compiler, target });
         add_component!("llvm-components" => LlvmTools { target });
-        add_component!("clippy" => Clippy { compiler, target });
-        add_component!("miri" => Miri { compiler, target });
+        add_component!("clippy" => Clippy { build_compiler: compiler, target });
+        add_component!("miri" => Miri { build_compiler: compiler, target });
         add_component!("analysis" => Analysis { compiler, target });
         add_component!("rustc-codegen-cranelift" => CodegenBackend {
             compiler: builder.compiler(stage, target),
diff --git a/src/bootstrap/src/core/build_steps/doc.rs b/src/bootstrap/src/core/build_steps/doc.rs
index 37418f640ac..d4539a0eb34 100644
--- a/src/bootstrap/src/core/build_steps/doc.rs
+++ b/src/bootstrap/src/core/build_steps/doc.rs
@@ -149,7 +149,7 @@ impl<P: Step> Step for RustbookSrc<P> {
             let mut rustbook_cmd = builder.tool_cmd(Tool::Rustbook);
 
             if let Some(compiler) = self.rustdoc_compiler {
-                let mut rustdoc = builder.rustdoc(compiler);
+                let mut rustdoc = builder.rustdoc_for_compiler(compiler);
                 rustdoc.pop();
                 let old_path = env::var_os("PATH").unwrap_or_default();
                 let new_path =
@@ -365,7 +365,7 @@ impl Step for Standalone {
             }
 
             let html = out.join(filename).with_extension("html");
-            let rustdoc = builder.rustdoc(compiler);
+            let rustdoc = builder.rustdoc_for_compiler(compiler);
             if up_to_date(&path, &html)
                 && up_to_date(&footer, &html)
                 && up_to_date(&favicon, &html)
@@ -463,7 +463,7 @@ impl Step for Releases {
         let html = out.join("releases.html");
         let tmppath = out.join("releases.md");
         let inpath = builder.src.join("RELEASES.md");
-        let rustdoc = builder.rustdoc(compiler);
+        let rustdoc = builder.rustdoc_for_compiler(compiler);
         if !up_to_date(&inpath, &html)
             || !up_to_date(&footer, &html)
             || !up_to_date(&favicon, &html)
@@ -811,7 +811,7 @@ impl Step for Rustc {
         let compiler = builder.compiler(stage, builder.config.host_target);
         builder.std(compiler, builder.config.host_target);
 
-        let _guard = builder.msg_sysroot_tool(
+        let _guard = builder.msg_rustc_tool(
             Kind::Doc,
             stage,
             format!("compiler{}", crate_description(&self.crates)),
@@ -901,6 +901,10 @@ impl Step for Rustc {
             builder.open_in_browser(index);
         }
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::doc("rustc", self.target).stage(self.stage))
+    }
 }
 
 macro_rules! tool_doc {
@@ -1018,6 +1022,10 @@ macro_rules! tool_doc {
                     })?
                 }
             }
+
+            fn metadata(&self) -> Option<StepMetadata> {
+                Some(StepMetadata::doc(stringify!($tool), self.target))
+            }
         }
     }
 }
diff --git a/src/bootstrap/src/core/build_steps/install.rs b/src/bootstrap/src/core/build_steps/install.rs
index 4513a138e19..f628330e9ed 100644
--- a/src/bootstrap/src/core/build_steps/install.rs
+++ b/src/bootstrap/src/core/build_steps/install.rs
@@ -215,13 +215,13 @@ install!((self, builder, _config),
     };
     Cargo, alias = "cargo", Self::should_build(_config), only_hosts: true, {
         let tarball = builder
-            .ensure(dist::Cargo { compiler: self.compiler, target: self.target })
+            .ensure(dist::Cargo { build_compiler: self.compiler, target: self.target })
             .expect("missing cargo");
         install_sh(builder, "cargo", self.compiler.stage, Some(self.target), &tarball);
     };
     RustAnalyzer, alias = "rust-analyzer", Self::should_build(_config), only_hosts: true, {
         if let Some(tarball) =
-            builder.ensure(dist::RustAnalyzer { compiler: self.compiler, target: self.target })
+            builder.ensure(dist::RustAnalyzer { build_compiler: self.compiler, target: self.target })
         {
             install_sh(builder, "rust-analyzer", self.compiler.stage, Some(self.target), &tarball);
         } else {
@@ -232,12 +232,12 @@ install!((self, builder, _config),
     };
     Clippy, alias = "clippy", Self::should_build(_config), only_hosts: true, {
         let tarball = builder
-            .ensure(dist::Clippy { compiler: self.compiler, target: self.target })
+            .ensure(dist::Clippy { build_compiler: self.compiler, target: self.target })
             .expect("missing clippy");
         install_sh(builder, "clippy", self.compiler.stage, Some(self.target), &tarball);
     };
     Miri, alias = "miri", Self::should_build(_config), only_hosts: true, {
-        if let Some(tarball) = builder.ensure(dist::Miri { compiler: self.compiler, target: self.target }) {
+        if let Some(tarball) = builder.ensure(dist::Miri { build_compiler: self.compiler, target: self.target }) {
             install_sh(builder, "miri", self.compiler.stage, Some(self.target), &tarball);
         } else {
             // Miri is only available on nightly
@@ -257,7 +257,7 @@ install!((self, builder, _config),
     };
     Rustfmt, alias = "rustfmt", Self::should_build(_config), only_hosts: true, {
         if let Some(tarball) = builder.ensure(dist::Rustfmt {
-            compiler: self.compiler,
+            build_compiler: self.compiler,
             target: self.target
         }) {
             install_sh(builder, "rustfmt", self.compiler.stage, Some(self.target), &tarball);
diff --git a/src/bootstrap/src/core/build_steps/perf.rs b/src/bootstrap/src/core/build_steps/perf.rs
index 4d61b38c876..108b7f90c14 100644
--- a/src/bootstrap/src/core/build_steps/perf.rs
+++ b/src/bootstrap/src/core/build_steps/perf.rs
@@ -157,7 +157,7 @@ Consider setting `rust.debuginfo-level = 1` in `bootstrap.toml`."#);
     if let Some(opts) = args.cmd.shared_opts()
         && opts.profiles.contains(&Profile::Doc)
     {
-        builder.ensure(Rustdoc { compiler });
+        builder.ensure(Rustdoc { target_compiler: compiler });
     }
 
     let sysroot = builder.ensure(Sysroot::new(compiler));
diff --git a/src/bootstrap/src/core/build_steps/run.rs b/src/bootstrap/src/core/build_steps/run.rs
index b2293fdd9b5..962dd372849 100644
--- a/src/bootstrap/src/core/build_steps/run.rs
+++ b/src/bootstrap/src/core/build_steps/run.rs
@@ -9,7 +9,7 @@ use clap_complete::{Generator, shells};
 
 use crate::core::build_steps::dist::distdir;
 use crate::core::build_steps::test;
-use crate::core::build_steps::tool::{self, SourceType, Tool};
+use crate::core::build_steps::tool::{self, RustcPrivateCompilers, SourceType, Tool};
 use crate::core::build_steps::vendor::{Vendor, default_paths_to_vendor};
 use crate::core::builder::{Builder, Kind, RunConfig, ShouldRun, Step};
 use crate::core::config::TargetSelection;
@@ -135,13 +135,13 @@ impl Step for Miri {
         }
 
         // This compiler runs on the host, we'll just use it for the target.
-        let target_compiler = builder.compiler(stage, target);
-        let miri_build = builder.ensure(tool::Miri { compiler: target_compiler, target });
-        // Rustc tools are off by one stage, so use the build compiler to run miri.
+        let compilers = RustcPrivateCompilers::new(builder, stage, target);
+        let miri_build = builder.ensure(tool::Miri::from_compilers(compilers));
         let host_compiler = miri_build.build_compiler;
 
         // Get a target sysroot for Miri.
-        let miri_sysroot = test::Miri::build_miri_sysroot(builder, target_compiler, target);
+        let miri_sysroot =
+            test::Miri::build_miri_sysroot(builder, compilers.target_compiler(), target);
 
         // # Run miri.
         // Running it via `cargo run` as that figures out the right dylib path.
@@ -465,8 +465,8 @@ impl Step for Rustfmt {
             std::process::exit(1);
         }
 
-        let compiler = builder.compiler(stage, host);
-        let rustfmt_build = builder.ensure(tool::Rustfmt { compiler, target: host });
+        let compilers = RustcPrivateCompilers::new(builder, stage, host);
+        let rustfmt_build = builder.ensure(tool::Rustfmt::from_compilers(compilers));
 
         let mut rustfmt = tool::prepare_tool_cargo(
             builder,
diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index 8bee00a9c13..09d2657b666 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -4,10 +4,12 @@
 //! However, this contains ~all test parts we expect people to be able to build and run locally.
 
 use std::collections::HashSet;
+use std::env::split_paths;
 use std::ffi::{OsStr, OsString};
 use std::path::{Path, PathBuf};
 use std::{env, fs, iter};
 
+use build_helper::exit;
 #[cfg(feature = "tracing")]
 use tracing::instrument;
 
@@ -17,7 +19,10 @@ use crate::core::build_steps::gcc::{Gcc, add_cg_gcc_cargo_flags};
 use crate::core::build_steps::llvm::get_llvm_version;
 use crate::core::build_steps::run::get_completion_paths;
 use crate::core::build_steps::synthetic_targets::MirOptPanicAbortSyntheticTarget;
-use crate::core::build_steps::tool::{self, COMPILETEST_ALLOW_FEATURES, SourceType, Tool};
+use crate::core::build_steps::tool::{
+    self, COMPILETEST_ALLOW_FEATURES, RustcPrivateCompilers, SourceType, Tool, ToolTargetBuildMode,
+    get_tool_target_compiler,
+};
 use crate::core::build_steps::toolstate::ToolState;
 use crate::core::build_steps::{compile, dist, llvm};
 use crate::core::builder::{
@@ -29,8 +34,8 @@ use crate::core::config::flags::{Subcommand, get_completion};
 use crate::utils::build_stamp::{self, BuildStamp};
 use crate::utils::exec::{BootstrapCommand, command};
 use crate::utils::helpers::{
-    self, LldThreads, add_rustdoc_cargo_linker_args, dylib_path, dylib_path_var, linker_args,
-    linker_flags, t, target_supports_cranelift_backend, up_to_date,
+    self, LldThreads, add_dylib_path, add_rustdoc_cargo_linker_args, dylib_path, dylib_path_var,
+    linker_args, linker_flags, t, target_supports_cranelift_backend, up_to_date,
 };
 use crate::utils::render_tests::{add_flags_and_try_run_tests, try_run_tests};
 use crate::{CLang, CodegenBackendKind, DocTests, GitRepo, Mode, PathSet, debug, envify};
@@ -226,7 +231,7 @@ impl Step for HtmlCheck {
 /// order to test cargo.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Cargotest {
-    stage: u32,
+    build_compiler: Compiler,
     host: TargetSelection,
 }
 
@@ -239,7 +244,19 @@ impl Step for Cargotest {
     }
 
     fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Cargotest { stage: run.builder.top_stage, host: run.target });
+        if run.builder.top_stage == 0 {
+            eprintln!(
+                "ERROR: running cargotest with stage 0 is currently unsupported. Use at least stage 1."
+            );
+            exit!(1);
+        }
+        // We want to build cargo stage N (where N == top_stage), and rustc stage N,
+        // and test both of these together.
+        // So we need to get a build compiler stage N-1 to build the stage N components.
+        run.builder.ensure(Cargotest {
+            build_compiler: run.builder.compiler(run.builder.top_stage - 1, run.target),
+            host: run.target,
+        });
     }
 
     /// Runs the `cargotest` tool as compiled in `stage` by the `host` compiler.
@@ -247,9 +264,19 @@ impl Step for Cargotest {
     /// This tool in `src/tools` will check out a few Rust projects and run `cargo
     /// test` to ensure that we don't regress the test suites there.
     fn run(self, builder: &Builder<'_>) {
-        let compiler = builder.compiler(self.stage, self.host);
-        builder.ensure(compile::Rustc::new(compiler, compiler.host));
-        let cargo = builder.ensure(tool::Cargo { compiler, target: compiler.host });
+        // cargotest's staging has several pieces:
+        // consider ./x test cargotest --stage=2.
+        //
+        // The test goal is to exercise a (stage 2 cargo, stage 2 rustc) pair through a stage 2
+        // cargotest tool.
+        // To produce the stage 2 cargo and cargotest, we need to do so with the stage 1 rustc and std.
+        // Importantly, the stage 2 rustc being tested (`tested_compiler`) via stage 2 cargotest is
+        // the rustc built by an earlier stage 1 rustc (the build_compiler). These are two different
+        // compilers!
+        let cargo =
+            builder.ensure(tool::Cargo::from_build_compiler(self.build_compiler, self.host));
+        let tested_compiler = builder.compiler(self.build_compiler.stage + 1, self.host);
+        builder.std(tested_compiler, self.host);
 
         // Note that this is a short, cryptic, and not scoped directory name. This
         // is currently to minimize the length of path on Windows where we otherwise
@@ -262,23 +289,28 @@ impl Step for Cargotest {
         cmd.arg(&cargo.tool_path)
             .arg(&out_dir)
             .args(builder.config.test_args())
-            .env("RUSTC", builder.rustc(compiler))
-            .env("RUSTDOC", builder.rustdoc(compiler));
+            .env("RUSTC", builder.rustc(tested_compiler))
+            .env("RUSTDOC", builder.rustdoc_for_compiler(tested_compiler));
         add_rustdoc_cargo_linker_args(
             &mut cmd,
             builder,
-            compiler.host,
+            tested_compiler.host,
             LldThreads::No,
-            compiler.stage,
+            tested_compiler.stage,
         );
         cmd.delay_failure().run(builder);
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::test("cargotest", self.host).stage(self.build_compiler.stage + 1))
+    }
 }
 
 /// Runs `cargo test` for cargo itself.
+/// We label these tests as "cargo self-tests".
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Cargo {
-    stage: u32,
+    build_compiler: Compiler,
     host: TargetSelection,
 }
 
@@ -295,35 +327,33 @@ impl Step for Cargo {
     }
 
     fn make_run(run: RunConfig<'_>) {
-        // If stage is explicitly set or not lower than 2, keep it. Otherwise, make sure it's at least 2
-        // as tests for this step don't work with a lower stage.
-        let stage = if run.builder.config.is_explicit_stage() || run.builder.top_stage >= 2 {
-            run.builder.top_stage
-        } else {
-            2
-        };
-
-        run.builder.ensure(Cargo { stage, host: run.target });
+        run.builder.ensure(Cargo {
+            build_compiler: get_tool_target_compiler(
+                run.builder,
+                ToolTargetBuildMode::Build(run.target),
+            ),
+            host: run.target,
+        });
     }
 
     /// Runs `cargo test` for `cargo` packaged with Rust.
     fn run(self, builder: &Builder<'_>) {
-        let stage = self.stage;
-
-        if stage < 2 {
-            eprintln!("WARNING: cargo tests on stage {stage} may not behave well.");
-            eprintln!("HELP: consider using stage 2");
-        }
-
-        let compiler = builder.compiler(stage, self.host);
-
-        let cargo = builder.ensure(tool::Cargo { compiler, target: self.host });
-        let compiler = cargo.build_compiler;
+        // When we do a "stage 1 cargo self-test", it means that we test the stage 1 rustc
+        // using stage 1 cargo. So we actually build cargo using the stage 0 compiler, and then
+        // run its tests against the stage 1 compiler (called `tested_compiler` below).
+        builder.ensure(tool::Cargo::from_build_compiler(self.build_compiler, self.host));
+
+        let tested_compiler = builder.compiler(self.build_compiler.stage + 1, self.host);
+        builder.std(tested_compiler, self.host);
+        // We also need to build rustdoc for cargo tests
+        // It will be located in the bindir of `tested_compiler`, so we don't need to explicitly
+        // pass its path to Cargo.
+        builder.rustdoc_for_compiler(tested_compiler);
 
         let cargo = tool::prepare_tool_cargo(
             builder,
-            compiler,
-            Mode::ToolRustc,
+            self.build_compiler,
+            Mode::ToolTarget,
             self.host,
             Kind::Test,
             Self::CRATE_PATH,
@@ -340,7 +370,25 @@ impl Step for Cargo {
         // Forcibly disable tests using nightly features since any changes to
         // those features won't be able to land.
         cargo.env("CARGO_TEST_DISABLE_NIGHTLY", "1");
-        cargo.env("PATH", path_for_cargo(builder, compiler));
+
+        // Configure PATH to find the right rustc. NB. we have to use PATH
+        // and not RUSTC because the Cargo test suite has tests that will
+        // fail if rustc is not spelled `rustc`.
+        cargo.env("PATH", bin_path_for_cargo(builder, tested_compiler));
+
+        // The `cargo` command configured above has dylib dir path set to the `build_compiler`'s
+        // libdir. That causes issues in cargo test, because the programs that cargo compiles are
+        // incorrectly picking that libdir, even though they should be picking the
+        // `tested_compiler`'s libdir. We thus have to override the precedence here.
+        let mut existing_dylib_paths = cargo
+            .get_envs()
+            .find(|(k, _)| *k == OsStr::new(dylib_path_var()))
+            .and_then(|(_, v)| v)
+            .map(|value| split_paths(value).collect::<Vec<PathBuf>>())
+            .unwrap_or_default();
+        existing_dylib_paths.insert(0, builder.rustc_libdir(tested_compiler));
+        add_dylib_path(existing_dylib_paths, &mut cargo);
+
         // Cargo's test suite uses `CARGO_RUSTC_CURRENT_DIR` to determine the path that `file!` is
         // relative to. Cargo no longer sets this env var, so we have to do that. This has to be the
         // same value as `-Zroot-dir`.
@@ -352,7 +400,7 @@ impl Step for Cargo {
                 crates: vec!["cargo".into()],
                 target: self.host.triple.to_string(),
                 host: self.host.triple.to_string(),
-                stage,
+                stage: self.build_compiler.stage + 1,
             },
             builder,
         );
@@ -364,8 +412,7 @@ impl Step for Cargo {
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct RustAnalyzer {
-    stage: u32,
-    host: TargetSelection,
+    compilers: RustcPrivateCompilers,
 }
 
 impl Step for RustAnalyzer {
@@ -378,19 +425,18 @@ impl Step for RustAnalyzer {
     }
 
     fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Self { stage: run.builder.top_stage, host: run.target });
+        run.builder.ensure(Self {
+            compilers: RustcPrivateCompilers::new(
+                run.builder,
+                run.builder.top_stage,
+                run.builder.host_target,
+            ),
+        });
     }
 
     /// Runs `cargo test` for rust-analyzer
     fn run(self, builder: &Builder<'_>) {
-        let stage = self.stage;
-        let host = self.host;
-        let compiler = builder.compiler(stage, host);
-        let compiler = tool::get_tool_rustc_compiler(builder, compiler);
-
-        // We don't need to build the whole Rust Analyzer for the proc-macro-srv test suite,
-        // but we do need the standard library to be present.
-        builder.ensure(compile::Rustc::new(compiler, host));
+        let host = self.compilers.target();
 
         let workspace_path = "src/tools/rust-analyzer";
         // until the whole RA test suite runs on `i686`, we only run
@@ -398,7 +444,7 @@ impl Step for RustAnalyzer {
         let crate_path = "src/tools/rust-analyzer/crates/proc-macro-srv";
         let mut cargo = tool::prepare_tool_cargo(
             builder,
-            compiler,
+            self.compilers.build_compiler(),
             Mode::ToolRustc,
             host,
             Kind::Test,
@@ -425,8 +471,7 @@ impl Step for RustAnalyzer {
 /// Runs `cargo test` for rustfmt.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Rustfmt {
-    stage: u32,
-    host: TargetSelection,
+    compilers: RustcPrivateCompilers,
 }
 
 impl Step for Rustfmt {
@@ -438,36 +483,39 @@ impl Step for Rustfmt {
     }
 
     fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Rustfmt { stage: run.builder.top_stage, host: run.target });
+        run.builder.ensure(Rustfmt {
+            compilers: RustcPrivateCompilers::new(
+                run.builder,
+                run.builder.top_stage,
+                run.builder.host_target,
+            ),
+        });
     }
 
     /// Runs `cargo test` for rustfmt.
     fn run(self, builder: &Builder<'_>) {
-        let stage = self.stage;
-        let host = self.host;
-        let compiler = builder.compiler(stage, host);
-
-        let tool_result = builder.ensure(tool::Rustfmt { compiler, target: self.host });
-        let compiler = tool_result.build_compiler;
+        let tool_result = builder.ensure(tool::Rustfmt::from_compilers(self.compilers));
+        let build_compiler = tool_result.build_compiler;
+        let target = self.compilers.target();
 
         let mut cargo = tool::prepare_tool_cargo(
             builder,
-            compiler,
+            build_compiler,
             Mode::ToolRustc,
-            host,
+            target,
             Kind::Test,
             "src/tools/rustfmt",
             SourceType::InTree,
             &[],
         );
 
-        let dir = testdir(builder, compiler.host);
+        let dir = testdir(builder, target);
         t!(fs::create_dir_all(&dir));
         cargo.env("RUSTFMT_TEST_DIR", dir);
 
         cargo.add_rustc_lib_path(builder);
 
-        run_cargo_test(cargo, &[], &[], "rustfmt", host, builder);
+        run_cargo_test(cargo, &[], &[], "rustfmt", target, builder);
     }
 }
 
@@ -542,12 +590,14 @@ impl Step for Miri {
         }
 
         // This compiler runs on the host, we'll just use it for the target.
-        let target_compiler = builder.compiler(stage, host);
+        let compilers = RustcPrivateCompilers::new(builder, stage, host);
 
         // Build our tools.
-        let miri = builder.ensure(tool::Miri { compiler: target_compiler, target: host });
+        let miri = builder.ensure(tool::Miri::from_compilers(compilers));
         // the ui tests also assume cargo-miri has been built
-        builder.ensure(tool::CargoMiri { compiler: target_compiler, target: host });
+        builder.ensure(tool::CargoMiri::from_compilers(compilers));
+
+        let target_compiler = compilers.target_compiler();
 
         // We also need sysroots, for Miri and for the host (the latter for build scripts).
         // This is for the tests so everything is done with the target compiler.
@@ -599,7 +649,7 @@ impl Step for Miri {
         cargo.env("MIRI_TEST_TARGET", target.rustc_target_arg());
 
         {
-            let _guard = builder.msg_sysroot_tool(Kind::Test, stage, "miri", host, target);
+            let _guard = builder.msg_rustc_tool(Kind::Test, stage, "miri", host, target);
             let _time = helpers::timeit(builder);
             cargo.run(builder);
         }
@@ -615,7 +665,7 @@ impl Step for Miri {
             cargo.args(["tests/pass", "tests/panic"]);
 
             {
-                let _guard = builder.msg_sysroot_tool(
+                let _guard = builder.msg_rustc_tool(
                     Kind::Test,
                     stage,
                     "miri (mir-opt-level 4)",
@@ -692,7 +742,7 @@ impl Step for CargoMiri {
         // Finally, run everything.
         let mut cargo = BootstrapCommand::from(cargo);
         {
-            let _guard = builder.msg_sysroot_tool(Kind::Test, stage, "cargo-miri", host, target);
+            let _guard = builder.msg_rustc_tool(Kind::Test, stage, "cargo-miri", host, target);
             let _time = helpers::timeit(builder);
             cargo.run(builder);
         }
@@ -762,7 +812,7 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Clippy {
-    host: TargetSelection,
+    compilers: RustcPrivateCompilers,
 }
 
 impl Step for Clippy {
@@ -775,23 +825,30 @@ impl Step for Clippy {
     }
 
     fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Clippy { host: run.target });
+        run.builder.ensure(Clippy {
+            compilers: RustcPrivateCompilers::new(
+                run.builder,
+                run.builder.top_stage,
+                run.builder.host_target,
+            ),
+        });
     }
 
     /// Runs `cargo test` for clippy.
     fn run(self, builder: &Builder<'_>) {
-        let stage = builder.top_stage;
-        let host = self.host;
+        let host = self.compilers.target();
+
         // We need to carefully distinguish the compiler that builds clippy, and the compiler
         // that is linked into the clippy being tested. `target_compiler` is the latter,
         // and it must also be used by clippy's test runner to build tests and their dependencies.
-        let target_compiler = builder.compiler(stage, host);
+        let compilers = self.compilers;
+        let target_compiler = compilers.target_compiler();
 
-        let tool_result = builder.ensure(tool::Clippy { compiler: target_compiler, target: host });
-        let tool_compiler = tool_result.build_compiler;
+        let tool_result = builder.ensure(tool::Clippy::from_compilers(compilers));
+        let build_compiler = tool_result.build_compiler;
         let mut cargo = tool::prepare_tool_cargo(
             builder,
-            tool_compiler,
+            build_compiler,
             Mode::ToolRustc,
             host,
             Kind::Test,
@@ -800,9 +857,10 @@ impl Step for Clippy {
             &[],
         );
 
-        cargo.env("RUSTC_TEST_SUITE", builder.rustc(tool_compiler));
-        cargo.env("RUSTC_LIB_PATH", builder.rustc_libdir(tool_compiler));
-        let host_libs = builder.stage_out(tool_compiler, Mode::ToolRustc).join(builder.cargo_dir());
+        cargo.env("RUSTC_TEST_SUITE", builder.rustc(build_compiler));
+        cargo.env("RUSTC_LIB_PATH", builder.rustc_libdir(build_compiler));
+        let host_libs =
+            builder.stage_out(build_compiler, Mode::ToolRustc).join(builder.cargo_dir());
         cargo.env("HOST_LIBS", host_libs);
 
         // Build the standard library that the tests can use.
@@ -831,8 +889,7 @@ impl Step for Clippy {
         cargo.add_rustc_lib_path(builder);
         let cargo = prepare_cargo_test(cargo, &[], &[], host, builder);
 
-        let _guard =
-            builder.msg_sysroot_tool(Kind::Test, tool_compiler.stage, "clippy", host, host);
+        let _guard = builder.msg_rustc_tool(Kind::Test, build_compiler.stage, "clippy", host, host);
 
         // Clippy reports errors if it blessed the outputs
         if cargo.allow_failure().run(builder) {
@@ -846,10 +903,7 @@ impl Step for Clippy {
     }
 }
 
-fn path_for_cargo(builder: &Builder<'_>, compiler: Compiler) -> OsString {
-    // Configure PATH to find the right rustc. NB. we have to use PATH
-    // and not RUSTC because the Cargo test suite has tests that will
-    // fail if rustc is not spelled `rustc`.
+fn bin_path_for_cargo(builder: &Builder<'_>, compiler: Compiler) -> OsString {
     let path = builder.sysroot(compiler).join("bin");
     let old_path = env::var_os("PATH").unwrap_or_default();
     env::join_paths(iter::once(path).chain(env::split_paths(&old_path))).expect("")
@@ -884,7 +938,7 @@ impl Step for RustdocTheme {
             .env("RUSTC_SYSROOT", builder.sysroot(self.compiler))
             .env("RUSTDOC_LIBDIR", builder.sysroot_target_libdir(self.compiler, self.compiler.host))
             .env("CFG_RELEASE_CHANNEL", &builder.config.channel)
-            .env("RUSTDOC_REAL", builder.rustdoc(self.compiler))
+            .env("RUSTDOC_REAL", builder.rustdoc_for_compiler(self.compiler))
             .env("RUSTC_BOOTSTRAP", "1");
         cmd.args(linker_args(builder, self.compiler.host, LldThreads::No, self.compiler.stage));
 
@@ -1043,7 +1097,11 @@ impl Step for RustdocGUI {
         let mut cmd = builder.tool_cmd(Tool::RustdocGUITest);
 
         let out_dir = builder.test_out(self.target).join("rustdoc-gui");
-        build_stamp::clear_if_dirty(builder, &out_dir, &builder.rustdoc(self.compiler));
+        build_stamp::clear_if_dirty(
+            builder,
+            &out_dir,
+            &builder.rustdoc_for_compiler(self.compiler),
+        );
 
         if let Some(src) = builder.config.src.to_str() {
             cmd.arg("--rust-src").arg(src);
@@ -1059,7 +1117,7 @@ impl Step for RustdocGUI {
 
         cmd.arg("--jobs").arg(builder.jobs().to_string());
 
-        cmd.env("RUSTDOC", builder.rustdoc(self.compiler))
+        cmd.env("RUSTDOC", builder.rustdoc_for_compiler(self.compiler))
             .env("RUSTC", builder.rustc(self.compiler));
 
         add_rustdoc_cargo_linker_args(
@@ -1095,7 +1153,7 @@ impl Step for RustdocGUI {
         }
 
         let _time = helpers::timeit(builder);
-        let _guard = builder.msg_sysroot_tool(
+        let _guard = builder.msg_rustc_tool(
             Kind::Test,
             self.compiler.stage,
             "rustdoc-gui",
@@ -1737,7 +1795,7 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
                 // If we're using `--stage 0`, we should provide the bootstrap cargo.
                 builder.initial_cargo.clone()
             } else {
-                builder.ensure(tool::Cargo { compiler, target: compiler.host }).tool_path
+                builder.ensure(tool::Cargo::from_build_compiler(compiler, compiler.host)).tool_path
             };
 
             cmd.arg("--cargo-path").arg(cargo_path);
@@ -1756,7 +1814,7 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
             || mode == "rustdoc-json"
             || suite == "coverage-run-rustdoc"
         {
-            cmd.arg("--rustdoc-path").arg(builder.rustdoc(compiler));
+            cmd.arg("--rustdoc-path").arg(builder.rustdoc_for_compiler(compiler));
         }
 
         if mode == "rustdoc-json" {
@@ -2272,7 +2330,7 @@ impl BookTest {
 
         // mdbook just executes a binary named "rustdoc", so we need to update
         // PATH so that it points to our rustdoc.
-        let mut rustdoc_path = builder.rustdoc(compiler);
+        let mut rustdoc_path = builder.rustdoc_for_compiler(compiler);
         rustdoc_path.pop();
         let old_path = env::var_os("PATH").unwrap_or_default();
         let new_path = env::join_paths(iter::once(rustdoc_path).chain(env::split_paths(&old_path)))
@@ -2595,7 +2653,7 @@ fn run_cargo_test<'a>(
     let mut cargo = prepare_cargo_test(cargo, libtest_args, crates, target, builder);
     let _time = helpers::timeit(builder);
     let _group = description.into().and_then(|what| {
-        builder.msg_sysroot_tool(Kind::Test, compiler.stage, what, compiler.host, target)
+        builder.msg_rustc_tool(Kind::Test, compiler.stage, what, compiler.host, target)
     });
 
     #[cfg(feature = "build-metrics")]
diff --git a/src/bootstrap/src/core/build_steps/tool.rs b/src/bootstrap/src/core/build_steps/tool.rs
index f5fa33b98f3..e3f49fa126e 100644
--- a/src/bootstrap/src/core/build_steps/tool.rs
+++ b/src/bootstrap/src/core/build_steps/tool.rs
@@ -71,13 +71,9 @@ impl Builder<'_> {
     ) -> 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,
-            ),
+            Mode::ToolRustc => {
+                self.msg_rustc_tool(kind, build_stage, format_args!("tool {tool}"), *host, *target)
+            }
             // doesn't depend on compiler, same as host compiler
             _ => self.msg(kind, build_stage, format_args!("tool {tool}"), *host, *target),
         }
@@ -90,11 +86,8 @@ impl Builder<'_> {
 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`.
+    /// Compiler used to build the tool.
     pub build_compiler: Compiler,
-    /// Target compiler passed to `Step`.
-    pub target_compiler: Compiler,
 }
 
 impl Step for ToolBuild {
@@ -108,22 +101,15 @@ impl Step for ToolBuild {
     ///
     /// 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 {
+    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
         let target = self.target;
         let mut tool = self.tool;
         let path = self.path;
 
-        let target_compiler = self.build_compiler;
-        self.build_compiler = if self.mode == Mode::ToolRustc {
-            get_tool_rustc_compiler(builder, self.build_compiler)
-        } else {
-            self.build_compiler
-        };
-
         match self.mode {
             Mode::ToolRustc => {
-                // If compiler was forced, its artifacts should have been prepared earlier.
-                if !self.build_compiler.is_forced_compiler() {
+                // FIXME: remove this, it's only needed for download-rustc...
+                if !self.build_compiler.is_forced_compiler() && builder.download_rustc() {
                     builder.std(self.build_compiler, self.build_compiler.host);
                     builder.ensure(compile::Rustc::new(self.build_compiler, target));
                 }
@@ -184,8 +170,7 @@ impl Step for ToolBuild {
             Kind::Build,
             self.mode,
             self.tool,
-            // A stage N tool is built with the stage N-1 compiler.
-            self.build_compiler.stage + 1,
+            self.build_compiler.stage,
             &self.build_compiler.host,
             &self.target,
         );
@@ -216,7 +201,7 @@ impl Step for ToolBuild {
                     .join(format!("lib{tool}.rlib")),
             };
 
-            ToolBuildResult { tool_path, build_compiler: self.build_compiler, target_compiler }
+            ToolBuildResult { tool_path, build_compiler: self.build_compiler }
         }
     }
 }
@@ -346,27 +331,6 @@ pub fn prepare_tool_cargo(
     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 == 1 {
-        // We shouldn't drop to stage0 compiler when using CI rustc.
-        return builder.compiler(1, builder.config.host_target);
-    }
-
-    // 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.host_target)
-}
-
 /// Determines how to build a `ToolTarget`, i.e. which compiler should be used to compile it.
 /// The compiler stage is automatically bumped if we need to cross-compile a stage 1 tool.
 pub enum ToolTargetBuildMode {
@@ -719,15 +683,21 @@ impl Step for RemoteTestServer {
     }
 }
 
-#[derive(Debug, Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
+/// Represents `Rustdoc` that either comes from the external stage0 sysroot or that is built
+/// locally.
+/// Rustdoc is special, because it both essentially corresponds to a `Compiler` (that can be
+/// externally provided), but also to a `ToolRustc` tool.
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 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,
+    /// If the stage of `target_compiler` is `0`, then rustdoc is externally provided.
+    /// Otherwise it is built locally.
+    pub target_compiler: Compiler,
 }
 
 impl Step for Rustdoc {
-    type Output = ToolBuildResult;
+    /// Path to the built rustdoc binary.
+    type Output = PathBuf;
+
     const DEFAULT: bool = true;
     const ONLY_HOSTS: bool = true;
 
@@ -736,26 +706,25 @@ impl Step for Rustdoc {
     }
 
     fn make_run(run: RunConfig<'_>) {
-        run.builder
-            .ensure(Rustdoc { compiler: run.builder.compiler(run.builder.top_stage, run.target) });
+        run.builder.ensure(Rustdoc {
+            target_compiler: run.builder.compiler(run.builder.top_stage, run.target),
+        });
     }
 
-    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
-        let target_compiler = self.compiler;
+    fn run(self, builder: &Builder<'_>) -> Self::Output {
+        let target_compiler = self.target_compiler;
         let target = target_compiler.host;
 
+        // If stage is 0, we use a prebuilt rustdoc from stage0
         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,
-            };
+            return builder.initial_rustdoc.clone();
         }
 
+        // If stage is higher, we build rustdoc instead
         let bin_rustdoc = || {
             let sysroot = builder.sysroot(target_compiler);
             let bindir = sysroot.join("bin");
@@ -767,10 +736,7 @@ impl Step for 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()
-        {
+        if builder.download_rustc() && builder.rust_info().is_managed_git_subrepository() {
             let files_to_track = &["src/librustdoc", "src/tools/rustdoc", "src/rustdoc-json-types"];
 
             // Check if unchanged
@@ -783,12 +749,7 @@ impl Step for Rustdoc {
 
                 let bin_rustdoc = bin_rustdoc();
                 builder.copy_link(&precompiled_rustdoc, &bin_rustdoc, FileType::Executable);
-
-                return ToolBuildResult {
-                    tool_path: bin_rustdoc,
-                    build_compiler: target_compiler,
-                    target_compiler,
-                };
+                return bin_rustdoc;
             }
         }
 
@@ -804,9 +765,10 @@ impl Step for Rustdoc {
             extra_features.push("jemalloc".to_string());
         }
 
-        let ToolBuildResult { tool_path, build_compiler, target_compiler } =
-            builder.ensure(ToolBuild {
-                build_compiler: target_compiler,
+        let compilers = RustcPrivateCompilers::from_target_compiler(builder, target_compiler);
+        let tool_path = builder
+            .ensure(ToolBuild {
+                build_compiler: compilers.build_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"
@@ -819,38 +781,41 @@ impl Step for Rustdoc {
                 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, FileType::Executable);
-            ToolBuildResult { tool_path: bin_rustdoc, build_compiler, target_compiler }
-        } else {
-            ToolBuildResult { tool_path, build_compiler, target_compiler }
+            })
+            .tool_path;
+
+        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, FileType::Executable);
+        bin_rustdoc
     }
 
     fn metadata(&self) -> Option<StepMetadata> {
         Some(
-            StepMetadata::build("rustdoc", self.compiler.host)
-                // rustdoc is ToolRustc, so stage N rustdoc is built by stage N-1 rustc
-                // FIXME: make this stage deduction automatic somehow
-                // FIXME: log the compiler that actually built ToolRustc steps
-                .stage(self.compiler.stage.saturating_sub(1)),
+            StepMetadata::build("rustdoc", self.target_compiler.host)
+                .stage(self.target_compiler.stage),
         )
     }
 }
 
+/// Builds the cargo tool.
+/// Note that it can be built using a stable compiler.
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct Cargo {
-    pub compiler: Compiler,
-    pub target: TargetSelection,
+    build_compiler: Compiler,
+    target: TargetSelection,
+}
+
+impl Cargo {
+    /// Returns `Cargo` that will be **compiled** by the passed compiler, for the given
+    /// `target`.
+    pub fn from_build_compiler(build_compiler: Compiler, target: TargetSelection) -> Self {
+        Self { build_compiler, target }
+    }
 }
 
 impl Step for Cargo {
@@ -865,7 +830,10 @@ impl Step for Cargo {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(Cargo {
-            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.host_target),
+            build_compiler: get_tool_target_compiler(
+                run.builder,
+                ToolTargetBuildMode::Build(run.target),
+            ),
             target: run.target,
         });
     }
@@ -873,19 +841,28 @@ impl Step for Cargo {
     fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
         builder.build.require_submodule("src/tools/cargo", None);
 
+        builder.std(self.build_compiler, self.target);
         builder.ensure(ToolBuild {
-            build_compiler: self.compiler,
+            build_compiler: self.build_compiler,
             target: self.target,
             tool: "cargo",
-            mode: Mode::ToolRustc,
+            mode: Mode::ToolTarget,
             path: "src/tools/cargo",
             source_type: SourceType::Submodule,
             extra_features: Vec::new(),
-            allow_features: "",
+            // Cargo is compilable with a stable compiler, but since we run in bootstrap,
+            // with RUSTC_BOOTSTRAP being set, some "clever" build scripts enable specialization
+            // based on this, which breaks stuff. We thus have to explicitly allow these features
+            // here.
+            allow_features: "min_specialization,specialization",
             cargo_args: Vec::new(),
             artifact_kind: ToolArtifactKind::Binary,
         })
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::build("cargo", self.target).built_by(self.build_compiler))
+    }
 }
 
 /// Represents a built LldWrapper, the `lld-wrapper` tool itself, and a directory
@@ -1066,8 +1043,13 @@ impl Step for WasmComponentLd {
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct RustAnalyzer {
-    pub compiler: Compiler,
-    pub target: TargetSelection,
+    compilers: RustcPrivateCompilers,
+}
+
+impl RustAnalyzer {
+    pub fn from_compilers(compilers: RustcPrivateCompilers) -> Self {
+        Self { compilers }
+    }
 }
 
 impl RustAnalyzer {
@@ -1086,15 +1068,16 @@ impl Step for RustAnalyzer {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(RustAnalyzer {
-            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.host_target),
-            target: run.target,
+            compilers: RustcPrivateCompilers::new(run.builder, run.builder.top_stage, run.target),
         });
     }
 
     fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
+        let build_compiler = self.compilers.build_compiler;
+        let target = self.compilers.target();
         builder.ensure(ToolBuild {
-            build_compiler: self.compiler,
-            target: self.target,
+            build_compiler,
+            target,
             tool: "rust-analyzer",
             mode: Mode::ToolRustc,
             path: "src/tools/rust-analyzer",
@@ -1105,16 +1088,29 @@ impl Step for RustAnalyzer {
             artifact_kind: ToolArtifactKind::Binary,
         })
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(
+            StepMetadata::build("rust-analyzer", self.compilers.target())
+                .built_by(self.compilers.build_compiler),
+        )
+    }
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct RustAnalyzerProcMacroSrv {
-    pub compiler: Compiler,
-    pub target: TargetSelection,
+    compilers: RustcPrivateCompilers,
+}
+
+impl RustAnalyzerProcMacroSrv {
+    pub fn from_compilers(compilers: RustcPrivateCompilers) -> Self {
+        Self { compilers }
+    }
 }
 
 impl Step for RustAnalyzerProcMacroSrv {
-    type Output = Option<ToolBuildResult>;
+    type Output = ToolBuildResult;
+
     const DEFAULT: bool = true;
     const ONLY_HOSTS: bool = true;
 
@@ -1131,15 +1127,14 @@ impl Step for RustAnalyzerProcMacroSrv {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(RustAnalyzerProcMacroSrv {
-            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.host_target),
-            target: run.target,
+            compilers: RustcPrivateCompilers::new(run.builder, run.builder.top_stage, run.target),
         });
     }
 
-    fn run(self, builder: &Builder<'_>) -> Option<ToolBuildResult> {
+    fn run(self, builder: &Builder<'_>) -> Self::Output {
         let tool_result = builder.ensure(ToolBuild {
-            build_compiler: self.compiler,
-            target: self.target,
+            build_compiler: self.compilers.build_compiler,
+            target: self.compilers.target(),
             tool: "rust-analyzer-proc-macro-srv",
             mode: Mode::ToolRustc,
             path: "src/tools/rust-analyzer/crates/proc-macro-srv-cli",
@@ -1152,7 +1147,7 @@ impl Step for RustAnalyzerProcMacroSrv {
 
         // 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");
+        let libexec_path = builder.sysroot(self.compilers.target_compiler).join("libexec");
         t!(fs::create_dir_all(&libexec_path));
         builder.copy_link(
             &tool_result.tool_path,
@@ -1160,7 +1155,14 @@ impl Step for RustAnalyzerProcMacroSrv {
             FileType::Executable,
         );
 
-        Some(tool_result)
+        tool_result
+    }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(
+            StepMetadata::build("rust-analyzer-proc-macro-srv", self.compilers.target())
+                .built_by(self.compilers.build_compiler),
+        )
     }
 }
 
@@ -1302,7 +1304,92 @@ impl Step for LibcxxVersionTool {
     }
 }
 
-macro_rules! tool_extended {
+/// Represents which compilers are involved in the compilation of a tool
+/// that depends on compiler internals (`rustc_private`).
+/// Their compilation looks like this:
+///
+/// - `build_compiler` (stage N-1) builds `target_compiler` (stage N) to produce .rlibs
+///     - These .rlibs are copied into the sysroot of `build_compiler`
+/// - `build_compiler` (stage N-1) builds `<tool>` (stage N)
+///     - `<tool>` links to .rlibs from `target_compiler`
+///
+/// Eventually, this could also be used for .rmetas and check builds, but so far we only deal with
+/// normal builds here.
+#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
+pub struct RustcPrivateCompilers {
+    /// Compiler that builds the tool and that builds `target_compiler`.
+    build_compiler: Compiler,
+    /// Compiler to which .rlib artifacts the tool links to.
+    /// The host target of this compiler corresponds to the target of the tool.
+    target_compiler: Compiler,
+}
+
+impl RustcPrivateCompilers {
+    /// Create compilers for a `rustc_private` tool with the given `stage` and for the given
+    /// `target`.
+    pub fn new(builder: &Builder<'_>, stage: u32, target: TargetSelection) -> Self {
+        let build_compiler = Self::build_compiler_from_stage(builder, stage);
+
+        // This is the compiler we'll link to
+        // FIXME: make 100% sure that `target_compiler` was indeed built with `build_compiler`...
+        let target_compiler = builder.compiler(build_compiler.stage + 1, target);
+
+        Self { build_compiler, target_compiler }
+    }
+
+    pub fn from_build_and_target_compiler(
+        build_compiler: Compiler,
+        target_compiler: Compiler,
+    ) -> Self {
+        Self { build_compiler, target_compiler }
+    }
+
+    /// Create rustc tool compilers from the build compiler.
+    pub fn from_build_compiler(
+        builder: &Builder<'_>,
+        build_compiler: Compiler,
+        target: TargetSelection,
+    ) -> Self {
+        let target_compiler = builder.compiler(build_compiler.stage + 1, target);
+        Self { build_compiler, target_compiler }
+    }
+
+    /// Create rustc tool compilers from the target compiler.
+    pub fn from_target_compiler(builder: &Builder<'_>, target_compiler: Compiler) -> Self {
+        Self {
+            build_compiler: Self::build_compiler_from_stage(builder, target_compiler.stage),
+            target_compiler,
+        }
+    }
+
+    fn build_compiler_from_stage(builder: &Builder<'_>, stage: u32) -> Compiler {
+        assert!(stage > 0);
+
+        if builder.download_rustc() && stage == 1 {
+            // We shouldn't drop to stage0 compiler when using CI rustc.
+            builder.compiler(1, builder.config.host_target)
+        } else {
+            builder.compiler(stage - 1, builder.config.host_target)
+        }
+    }
+
+    pub fn build_compiler(&self) -> Compiler {
+        self.build_compiler
+    }
+
+    pub fn target_compiler(&self) -> Compiler {
+        self.target_compiler
+    }
+
+    /// Target of the tool being compiled
+    pub fn target(&self) -> TargetSelection {
+        self.target_compiler.host
+    }
+}
+
+/// Creates a step that builds an extended `Mode::ToolRustc` tool
+/// and installs it into the sysroot of a corresponding compiler.
+macro_rules! tool_rustc_extended {
     (
         $name:ident {
             path: $path:expr,
@@ -1316,8 +1403,15 @@ macro_rules! tool_extended {
     ) => {
         #[derive(Debug, Clone, Hash, PartialEq, Eq)]
         pub struct $name {
-            pub compiler: Compiler,
-            pub target: TargetSelection,
+            compilers: RustcPrivateCompilers,
+        }
+
+        impl $name {
+            pub fn from_compilers(compilers: RustcPrivateCompilers) -> Self {
+                Self {
+                    compilers,
+                }
+            }
         }
 
         impl Step for $name {
@@ -1326,7 +1420,7 @@ macro_rules! tool_extended {
             const ONLY_HOSTS: bool = true;
 
             fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-                should_run_tool_build_step(
+                should_run_extended_rustc_tool(
                     run,
                     $tool_name,
                     $path,
@@ -1336,17 +1430,15 @@ macro_rules! tool_extended {
 
             fn make_run(run: RunConfig<'_>) {
                 run.builder.ensure($name {
-                    compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.host_target),
-                    target: run.target,
+                    compilers: RustcPrivateCompilers::new(run.builder, run.builder.top_stage, run.target),
                 });
             }
 
             fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
-                let Self { compiler, target } = self;
-                run_tool_build_step(
+                let Self { compilers } = self;
+                build_extended_rustc_tool(
                     builder,
-                    compiler,
-                    target,
+                    compilers,
                     $tool_name,
                     $path,
                     None $( .or(Some(&$add_bins_to_sysroot)) )?,
@@ -1356,18 +1448,16 @@ macro_rules! tool_extended {
             }
 
             fn metadata(&self) -> Option<StepMetadata> {
-                // FIXME: refactor extended tool steps to make the build_compiler explicit,
-                // it is offset by one now for rustc tools
                 Some(
-                    StepMetadata::build($tool_name, self.target)
-                        .built_by(self.compiler.with_stage(self.compiler.stage.saturating_sub(1)))
+                    StepMetadata::build($tool_name, self.compilers.target())
+                        .built_by(self.compilers.build_compiler)
                 )
             }
         }
     }
 }
 
-fn should_run_tool_build_step<'a>(
+fn should_run_extended_rustc_tool<'a>(
     run: ShouldRun<'a>,
     tool_name: &'static str,
     path: &'static str,
@@ -1391,39 +1481,38 @@ fn should_run_tool_build_step<'a>(
     )
 }
 
-#[expect(clippy::too_many_arguments)] // silence overeager clippy lint
-fn run_tool_build_step(
+fn build_extended_rustc_tool(
     builder: &Builder<'_>,
-    compiler: Compiler,
-    target: TargetSelection,
+    compilers: RustcPrivateCompilers,
     tool_name: &'static str,
     path: &'static str,
     add_bins_to_sysroot: Option<&[&str]>,
     add_features: Option<fn(&Builder<'_>, TargetSelection, &mut Vec<String>)>,
     cargo_args: Option<&[&'static str]>,
 ) -> ToolBuildResult {
+    let target = compilers.target();
     let mut extra_features = Vec::new();
     if let Some(func) = add_features {
         func(builder, target, &mut extra_features);
     }
 
-    let ToolBuildResult { tool_path, build_compiler, target_compiler } =
-        builder.ensure(ToolBuild {
-            build_compiler: compiler,
-            target,
-            tool: tool_name,
-            mode: Mode::ToolRustc,
-            path,
-            extra_features,
-            source_type: SourceType::InTree,
-            allow_features: "",
-            cargo_args: cargo_args.unwrap_or_default().iter().map(|s| String::from(*s)).collect(),
-            artifact_kind: ToolArtifactKind::Binary,
-        });
-
+    let build_compiler = compilers.build_compiler;
+    let ToolBuildResult { tool_path, .. } = builder.ensure(ToolBuild {
+        build_compiler,
+        target,
+        tool: tool_name,
+        mode: Mode::ToolRustc,
+        path,
+        extra_features,
+        source_type: SourceType::InTree,
+        allow_features: "",
+        cargo_args: cargo_args.unwrap_or_default().iter().map(|s| String::from(*s)).collect(),
+        artifact_kind: ToolArtifactKind::Binary,
+    });
+
+    let target_compiler = compilers.target_compiler;
     if let Some(add_bins_to_sysroot) = add_bins_to_sysroot
         && !add_bins_to_sysroot.is_empty()
-        && target_compiler.stage > 0
     {
         let bindir = builder.sysroot(target_compiler).join("bin");
         t!(fs::create_dir_all(&bindir));
@@ -1435,25 +1524,25 @@ fn run_tool_build_step(
 
         // 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 }
+        ToolBuildResult { tool_path: path, build_compiler }
     } else {
-        ToolBuildResult { tool_path, build_compiler, target_compiler }
+        ToolBuildResult { tool_path, build_compiler }
     }
 }
 
-tool_extended!(Cargofmt {
+tool_rustc_extended!(Cargofmt {
     path: "src/tools/rustfmt",
     tool_name: "cargo-fmt",
     stable: true,
     add_bins_to_sysroot: ["cargo-fmt"]
 });
-tool_extended!(CargoClippy {
+tool_rustc_extended!(CargoClippy {
     path: "src/tools/clippy",
     tool_name: "cargo-clippy",
     stable: true,
     add_bins_to_sysroot: ["cargo-clippy"]
 });
-tool_extended!(Clippy {
+tool_rustc_extended!(Clippy {
     path: "src/tools/clippy",
     tool_name: "clippy-driver",
     stable: true,
@@ -1464,7 +1553,7 @@ tool_extended!(Clippy {
         }
     }
 });
-tool_extended!(Miri {
+tool_rustc_extended!(Miri {
     path: "src/tools/miri",
     tool_name: "miri",
     stable: false,
@@ -1472,13 +1561,13 @@ tool_extended!(Miri {
     // Always compile also tests when building miri. Otherwise feature unification can cause rebuilds between building and testing miri.
     cargo_args: &["--all-targets"],
 });
-tool_extended!(CargoMiri {
+tool_rustc_extended!(CargoMiri {
     path: "src/tools/miri/cargo-miri",
     tool_name: "cargo-miri",
     stable: false,
     add_bins_to_sysroot: ["cargo-miri"]
 });
-tool_extended!(Rustfmt {
+tool_rustc_extended!(Rustfmt {
     path: "src/tools/rustfmt",
     tool_name: "rustfmt",
     stable: true,
diff --git a/src/bootstrap/src/core/builder/cargo.rs b/src/bootstrap/src/core/builder/cargo.rs
index 6b3236ef47e..1d0c9da694f 100644
--- a/src/bootstrap/src/core/builder/cargo.rs
+++ b/src/bootstrap/src/core/builder/cargo.rs
@@ -508,7 +508,7 @@ impl Builder<'_> {
                 }
                 _ => panic!("doc mode {mode:?} not expected"),
             };
-            let rustdoc = self.rustdoc(compiler);
+            let rustdoc = self.rustdoc_for_compiler(compiler);
             build_stamp::clear_if_dirty(self, &my_out, &rustdoc);
         }
 
@@ -822,7 +822,7 @@ impl Builder<'_> {
         }
 
         let rustdoc_path = match cmd_kind {
-            Kind::Doc | Kind::Test | Kind::MiriTest => self.rustdoc(compiler),
+            Kind::Doc | Kind::Test | Kind::MiriTest => self.rustdoc_for_compiler(compiler),
             _ => PathBuf::from("/path/to/nowhere/rustdoc/not/required"),
         };
 
diff --git a/src/bootstrap/src/core/builder/mod.rs b/src/bootstrap/src/core/builder/mod.rs
index 20f3fee1c6c..f84565fccfd 100644
--- a/src/bootstrap/src/core/builder/mod.rs
+++ b/src/bootstrap/src/core/builder/mod.rs
@@ -16,6 +16,7 @@ use tracing::instrument;
 pub use self::cargo::{Cargo, cargo_profile_var};
 pub use crate::Compiler;
 use crate::core::build_steps::compile::{Std, StdLink};
+use crate::core::build_steps::tool::RustcPrivateCompilers;
 use crate::core::build_steps::{
     check, clean, clippy, compile, dist, doc, gcc, install, llvm, run, setup, test, tool, vendor,
 };
@@ -1543,8 +1544,11 @@ You have to build a stage1 compiler for `{}` first, and then use it to build a s
             .map(|entry| entry.path())
     }
 
-    pub fn rustdoc(&self, compiler: Compiler) -> PathBuf {
-        self.ensure(tool::Rustdoc { compiler }).tool_path
+    /// Returns a path to `Rustdoc` that "belongs" to the `target_compiler`.
+    /// It can be either a stage0 rustdoc or a locally built rustdoc that *links* to
+    /// `target_compiler`.
+    pub fn rustdoc_for_compiler(&self, target_compiler: Compiler) -> PathBuf {
+        self.ensure(tool::Rustdoc { target_compiler })
     }
 
     pub fn cargo_clippy_cmd(&self, run_compiler: Compiler) -> BootstrapCommand {
@@ -1560,10 +1564,13 @@ You have to build a stage1 compiler for `{}` first, and then use it to build a s
             return cmd;
         }
 
-        let _ =
-            self.ensure(tool::Clippy { compiler: run_compiler, target: self.build.host_target });
-        let cargo_clippy = self
-            .ensure(tool::CargoClippy { compiler: run_compiler, target: self.build.host_target });
+        // FIXME: double check that `run_compiler`'s stage is what we want to use
+        let compilers =
+            RustcPrivateCompilers::new(self, run_compiler.stage, self.build.host_target);
+        assert_eq!(run_compiler, compilers.target_compiler());
+
+        let _ = self.ensure(tool::Clippy::from_compilers(compilers));
+        let cargo_clippy = self.ensure(tool::CargoClippy::from_compilers(compilers));
         let mut dylib_path = helpers::dylib_path();
         dylib_path.insert(0, self.sysroot(run_compiler).join("lib"));
 
@@ -1575,11 +1582,14 @@ You have to build a stage1 compiler for `{}` first, and then use it to build a s
 
     pub fn cargo_miri_cmd(&self, run_compiler: Compiler) -> BootstrapCommand {
         assert!(run_compiler.stage > 0, "miri can not be invoked at stage 0");
+
+        let compilers =
+            RustcPrivateCompilers::new(self, run_compiler.stage, self.build.host_target);
+        assert_eq!(run_compiler, compilers.target_compiler());
+
         // Prepare the tools
-        let miri =
-            self.ensure(tool::Miri { compiler: run_compiler, target: self.build.host_target });
-        let cargo_miri =
-            self.ensure(tool::CargoMiri { compiler: run_compiler, target: self.build.host_target });
+        let miri = self.ensure(tool::Miri::from_compilers(compilers));
+        let cargo_miri = self.ensure(tool::CargoMiri::from_compilers(compilers));
         // Invoke cargo-miri, make sure it can find miri and cargo.
         let mut cmd = command(cargo_miri.tool_path);
         cmd.env("MIRI", &miri.tool_path);
@@ -1604,7 +1614,7 @@ You have to build a stage1 compiler for `{}` first, and then use it to build a s
             // equivalently to rustc.
             .env("RUSTDOC_LIBDIR", self.rustc_libdir(compiler))
             .env("CFG_RELEASE_CHANNEL", &self.config.channel)
-            .env("RUSTDOC_REAL", self.rustdoc(compiler))
+            .env("RUSTDOC_REAL", self.rustdoc_for_compiler(compiler))
             .env("RUSTC_BOOTSTRAP", "1");
 
         cmd.arg("-Wrustdoc::invalid_codeblock_attributes");
@@ -1728,11 +1738,11 @@ You have to build a stage1 compiler for `{}` first, and then use it to build a s
     /// Ensure that a given step is built *only if it's supposed to be built by default*, returning
     /// its output. This will cache the step, so it's safe (and good!) to call this as often as
     /// needed to ensure that all dependencies are build.
-    pub(crate) fn ensure_if_default<T, S: Step<Output = Option<T>>>(
+    pub(crate) fn ensure_if_default<T, S: Step<Output = T>>(
         &'a self,
         step: S,
         kind: Kind,
-    ) -> S::Output {
+    ) -> Option<S::Output> {
         let desc = StepDescription::from::<S>(kind);
         let should_run = (desc.should_run)(ShouldRun::new(self, desc.kind));
 
@@ -1744,7 +1754,7 @@ You have to build a stage1 compiler for `{}` first, and then use it to build a s
         }
 
         // Only execute if it's supposed to run as default
-        if desc.default && should_run.is_really_default() { self.ensure(step) } else { None }
+        if desc.default && should_run.is_really_default() { Some(self.ensure(step)) } else { None }
     }
 
     /// Checks if any of the "should_run" paths is in the `Builder` paths.
diff --git a/src/bootstrap/src/core/builder/tests.rs b/src/bootstrap/src/core/builder/tests.rs
index f012645b7ef..139ddc9ed24 100644
--- a/src/bootstrap/src/core/builder/tests.rs
+++ b/src/bootstrap/src/core/builder/tests.rs
@@ -279,13 +279,6 @@ mod defaults {
             first(cache.all::<tool::ErrorIndex>()),
             &[tool::ErrorIndex { compiler: Compiler::new(1, a) }]
         );
-        // docs should be built with the stage0 compiler, not with the stage0 artifacts.
-        // recall that rustdoc is off-by-one: `stage` is the compiler rustdoc is _linked_ to,
-        // not the one it was built by.
-        assert_eq!(
-            first(cache.all::<tool::Rustdoc>()),
-            &[tool::Rustdoc { compiler: Compiler::new(1, a) },]
-        );
     }
 }
 
@@ -337,12 +330,6 @@ mod dist {
             first(builder.cache.all::<tool::ErrorIndex>()),
             &[tool::ErrorIndex { compiler: Compiler::new(1, a) }]
         );
-        // This is actually stage 1, but Rustdoc::run swaps out the compiler with
-        // stage minus 1 if --stage is not 0. Very confusing!
-        assert_eq!(
-            first(builder.cache.all::<tool::Rustdoc>()),
-            &[tool::Rustdoc { compiler: Compiler::new(2, a) },]
-        );
     }
 }
 
@@ -569,36 +556,6 @@ fn test_is_builder_target() {
     }
 }
 
-#[test]
-fn test_get_tool_rustc_compiler() {
-    let mut config = configure("build", &[], &[]);
-    config.download_rustc_commit = None;
-    let build = Build::new(config);
-    let builder = Builder::new(&build);
-
-    let target_triple_1 = TargetSelection::from_user(TEST_TRIPLE_1);
-
-    let compiler = Compiler::new(2, target_triple_1);
-    let expected = Compiler::new(1, target_triple_1);
-    let actual = tool::get_tool_rustc_compiler(&builder, compiler);
-    assert_eq!(expected, actual);
-
-    let compiler = Compiler::new(1, target_triple_1);
-    let expected = Compiler::new(0, target_triple_1);
-    let actual = tool::get_tool_rustc_compiler(&builder, compiler);
-    assert_eq!(expected, actual);
-
-    let mut config = configure("build", &[], &[]);
-    config.download_rustc_commit = Some("".to_owned());
-    let build = Build::new(config);
-    let builder = Builder::new(&build);
-
-    let compiler = Compiler::new(1, target_triple_1);
-    let expected = Compiler::new(1, target_triple_1);
-    let actual = tool::get_tool_rustc_compiler(&builder, compiler);
-    assert_eq!(expected, actual);
-}
-
 /// When bootstrap detects a step dependency cycle (which is a bug), its panic
 /// message should show the actual steps on the stack, not just several copies
 /// of `Any { .. }`.
@@ -657,7 +614,7 @@ mod snapshot {
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
-        [build] rustdoc 0 <host>
+        [build] rustdoc 1 <host>
         ");
     }
 
@@ -680,10 +637,10 @@ mod snapshot {
         [build] rustc 2 <host> -> std 2 <host>
         [build] rustc 1 <host> -> std 1 <target1>
         [build] rustc 2 <host> -> std 2 <target1>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         [build] llvm <target1>
         [build] rustc 1 <host> -> rustc 2 <target1>
-        [build] rustdoc 1 <target1>
+        [build] rustdoc 2 <target1>
         ");
     }
 
@@ -763,6 +720,23 @@ mod snapshot {
     }
 
     #[test]
+    fn build_compiler_codegen_backend() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx
+                .config("build")
+                .args(&["--set", "rust.codegen-backends=['llvm', 'cranelift']"])
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 0 <host> -> rustc_codegen_cranelift 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustdoc 1 <host>
+        "
+        );
+    }
+
+    #[test]
     fn build_compiler_tools() {
         let ctx = TestCtx::new();
         insta::assert_snapshot!(
@@ -780,7 +754,7 @@ mod snapshot {
         [build] rustc 1 <host> -> LldWrapper 2 <host>
         [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
         [build] rustc 2 <host> -> std 2 <host>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         "
         );
     }
@@ -809,7 +783,7 @@ mod snapshot {
         [build] rustc 1 <host> -> rustc 2 <target1>
         [build] rustc 1 <host> -> LldWrapper 2 <target1>
         [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <target1>
-        [build] rustdoc 1 <target1>
+        [build] rustdoc 2 <target1>
         "
         );
     }
@@ -998,7 +972,7 @@ mod snapshot {
             .render_steps(), @r"
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
-        [build] rustdoc 0 <host>
+        [build] rustdoc 1 <host>
         [doc] std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         ");
     }
@@ -1027,6 +1001,15 @@ mod snapshot {
     }
 
     #[test]
+    fn build_cargo() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("build")
+                .paths(&["cargo"])
+            .render_steps(), @"[build] rustc 0 <host> -> cargo 1 <host>");
+    }
+
+    #[test]
     fn dist_default_stage() {
         let ctx = TestCtx::new();
         assert_eq!(ctx.config("dist").path("compiler").create_config().stage, 2);
@@ -1047,7 +1030,7 @@ mod snapshot {
         [build] rustc 0 <host> -> rustc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         [doc] std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 2 <host> -> std 2 <host>
         [build] rustc 0 <host> -> LintDocs 1 <host>
@@ -1089,7 +1072,7 @@ mod snapshot {
         [build] rustc 1 <host> -> LldWrapper 2 <host>
         [build] rustc 1 <host> -> WasmComponentLd 2 <host>
         [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         [doc] std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 2 <host> -> std 2 <host>
         [build] rustc 0 <host> -> LintDocs 1 <host>
@@ -1097,16 +1080,19 @@ mod snapshot {
         [dist] docs <host>
         [doc] std 2 <host> crates=[]
         [dist] mingw <host>
+        [build] rustc 1 <host> -> rust-analyzer-proc-macro-srv 2 <host>
         [build] rustc 0 <host> -> GenerateCopyright 1 <host>
         [dist] rustc <host>
         [dist] rustc 1 <host> -> std 1 <host>
         [dist] src <>
-        [build] rustc 0 <host> -> rustfmt 1 <host>
-        [build] rustc 0 <host> -> cargo-fmt 1 <host>
-        [build] rustc 0 <host> -> clippy-driver 1 <host>
-        [build] rustc 0 <host> -> cargo-clippy 1 <host>
-        [build] rustc 0 <host> -> miri 1 <host>
-        [build] rustc 0 <host> -> cargo-miri 1 <host>
+        [build] rustc 1 <host> -> cargo 2 <host>
+        [build] rustc 1 <host> -> rust-analyzer 2 <host>
+        [build] rustc 1 <host> -> rustfmt 2 <host>
+        [build] rustc 1 <host> -> cargo-fmt 2 <host>
+        [build] rustc 1 <host> -> clippy-driver 2 <host>
+        [build] rustc 1 <host> -> cargo-clippy 2 <host>
+        [build] rustc 1 <host> -> miri 2 <host>
+        [build] rustc 1 <host> -> cargo-miri 2 <host>
         ");
     }
 
@@ -1125,7 +1111,7 @@ mod snapshot {
         [build] rustc 0 <host> -> rustc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         [doc] std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [doc] std 2 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 2 <host> -> std 2 <host>
@@ -1162,7 +1148,7 @@ mod snapshot {
         [build] rustc 0 <host> -> rustc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         [doc] std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 2 <host> -> std 2 <host>
         [build] rustc 0 <host> -> LintDocs 1 <host>
@@ -1176,7 +1162,7 @@ mod snapshot {
         [dist] rustc <host>
         [build] llvm <target1>
         [build] rustc 1 <host> -> rustc 2 <target1>
-        [build] rustdoc 1 <target1>
+        [build] rustdoc 2 <target1>
         [dist] rustc <target1>
         [dist] rustc 1 <host> -> std 1 <host>
         [dist] src <>
@@ -1199,7 +1185,7 @@ mod snapshot {
         [build] rustc 0 <host> -> rustc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         [doc] std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [doc] std 2 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 2 <host> -> std 2 <host>
@@ -1217,7 +1203,7 @@ mod snapshot {
         [dist] rustc <host>
         [build] llvm <target1>
         [build] rustc 1 <host> -> rustc 2 <target1>
-        [build] rustdoc 1 <target1>
+        [build] rustdoc 2 <target1>
         [dist] rustc <target1>
         [dist] rustc 1 <host> -> std 1 <host>
         [dist] rustc 1 <host> -> std 1 <target1>
@@ -1241,7 +1227,7 @@ mod snapshot {
         [build] rustc 0 <host> -> rustc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         [doc] std 2 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 2 <host> -> std 2 <host>
         [build] rustc 0 <host> -> RustInstaller 1 <host>
@@ -1273,7 +1259,7 @@ mod snapshot {
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
         [build] rustc 1 <host> -> WasmComponentLd 2 <host>
-        [build] rustdoc 1 <host>
+        [build] rustdoc 2 <host>
         [doc] std 2 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 2 <host> -> std 2 <host>
         [build] rustc 1 <host> -> std 1 <target1>
@@ -1286,17 +1272,20 @@ mod snapshot {
         [build] llvm <target1>
         [build] rustc 1 <host> -> rustc 2 <target1>
         [build] rustc 1 <host> -> WasmComponentLd 2 <target1>
-        [build] rustdoc 1 <target1>
+        [build] rustdoc 2 <target1>
+        [build] rustc 1 <host> -> rust-analyzer-proc-macro-srv 2 <target1>
         [build] rustc 0 <host> -> GenerateCopyright 1 <host>
         [dist] rustc <target1>
         [dist] rustc 1 <host> -> std 1 <target1>
         [dist] src <>
-        [build] rustc 0 <host> -> rustfmt 1 <target1>
-        [build] rustc 0 <host> -> cargo-fmt 1 <target1>
-        [build] rustc 0 <host> -> clippy-driver 1 <target1>
-        [build] rustc 0 <host> -> cargo-clippy 1 <target1>
-        [build] rustc 0 <host> -> miri 1 <target1>
-        [build] rustc 0 <host> -> cargo-miri 1 <target1>
+        [build] rustc 1 <host> -> cargo 2 <target1>
+        [build] rustc 1 <host> -> rust-analyzer 2 <target1>
+        [build] rustc 1 <host> -> rustfmt 2 <target1>
+        [build] rustc 1 <host> -> cargo-fmt 2 <target1>
+        [build] rustc 1 <host> -> clippy-driver 2 <target1>
+        [build] rustc 1 <host> -> cargo-clippy 2 <target1>
+        [build] rustc 1 <host> -> miri 2 <target1>
+        [build] rustc 1 <host> -> cargo-miri 2 <target1>
         [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <target1>
         ");
     }
@@ -1611,6 +1600,58 @@ mod snapshot {
     }
 
     #[test]
+    fn test_cargo_stage_1() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("test")
+                .path("cargo")
+                .render_steps(), @r"
+        [build] rustc 0 <host> -> cargo 1 <host>
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustdoc 1 <host>
+        [build] rustdoc 0 <host>
+        ");
+    }
+
+    #[test]
+    fn test_cargo_stage_2() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("test")
+                .path("cargo")
+                .stage(2)
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustc 1 <host> -> cargo 2 <host>
+        [build] rustc 1 <host> -> rustc 2 <host>
+        [build] rustc 2 <host> -> std 2 <host>
+        [build] rustdoc 2 <host>
+        [build] rustdoc 1 <host>
+        ");
+    }
+
+    #[test]
+    fn test_cargotest() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("test")
+                .path("cargotest")
+                .render_steps(), @r"
+        [build] rustc 0 <host> -> cargo 1 <host>
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustc 0 <host> -> CargoTest 1 <host>
+        [build] rustdoc 1 <host>
+        [test] cargotest 1 <host>
+        ");
+    }
+
+    #[test]
     fn doc_library() {
         let ctx = TestCtx::new();
         insta::assert_snapshot!(
@@ -1619,7 +1660,7 @@ mod snapshot {
                 .render_steps(), @r"
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
-        [build] rustdoc 0 <host>
+        [build] rustdoc 1 <host>
         [doc] std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         ");
     }
@@ -1633,7 +1674,7 @@ mod snapshot {
                 .render_steps(), @r"
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
-        [build] rustdoc 0 <host>
+        [build] rustdoc 1 <host>
         [doc] std 1 <host> crates=[core]
         ");
     }
@@ -1648,7 +1689,7 @@ mod snapshot {
                 .render_steps(), @r"
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
-        [build] rustdoc 0 <host>
+        [build] rustdoc 1 <host>
         [doc] std 1 <host> crates=[core]
         ");
     }
@@ -1678,7 +1719,7 @@ mod snapshot {
                 .render_steps(), @r"
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
-        [build] rustdoc 0 <host>
+        [build] rustdoc 1 <host>
         [doc] std 1 <host> crates=[alloc,core]
         ");
     }
@@ -1694,10 +1735,105 @@ mod snapshot {
                 .render_steps(), @r"
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
-        [build] rustdoc 0 <host>
+        [build] rustdoc 1 <host>
         [doc] std 1 <target1> crates=[alloc,core]
         ");
     }
+
+    #[test]
+    fn doc_compiler_stage_0() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("compiler")
+                .stage(0)
+                .render_steps(), @r"
+        [build] rustdoc 0 <host>
+        [build] llvm <host>
+        [doc] rustc 0 <host>
+        ");
+    }
+
+    #[test]
+    fn doc_compiler_stage_1() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("compiler")
+                .stage(1)
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustdoc 1 <host>
+        [doc] rustc 1 <host>
+        ");
+    }
+
+    #[test]
+    fn doc_compiler_stage_2() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("compiler")
+                .stage(2)
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustc 1 <host> -> rustc 2 <host>
+        [build] rustc 2 <host> -> std 2 <host>
+        [build] rustdoc 2 <host>
+        [doc] rustc 2 <host>
+        ");
+    }
+
+    #[test]
+    fn doc_compiletest_stage_0() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("src/tools/compiletest")
+                .stage(0)
+                .render_steps(), @r"
+        [build] rustdoc 0 <host>
+        [doc] Compiletest <host>
+        ");
+    }
+
+    #[test]
+    fn doc_compiletest_stage_1() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("src/tools/compiletest")
+                .stage(1)
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustdoc 1 <host>
+        [doc] Compiletest <host>
+        ");
+    }
+
+    #[test]
+    fn doc_compiletest_stage_2() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("src/tools/compiletest")
+                .stage(2)
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustc 1 <host> -> rustc 2 <host>
+        [build] rustc 2 <host> -> std 2 <host>
+        [build] rustdoc 2 <host>
+        [doc] Compiletest <host>
+        ");
+    }
 }
 
 struct ExecutedSteps {
diff --git a/src/bootstrap/src/lib.rs b/src/bootstrap/src/lib.rs
index e49513a2116..42192f1d721 100644
--- a/src/bootstrap/src/lib.rs
+++ b/src/bootstrap/src/lib.rs
@@ -1105,17 +1105,6 @@ impl Build {
         self.msg(Kind::Doc, compiler.stage, what, compiler.host, target.into())
     }
 
-    #[must_use = "Groups should not be dropped until the Step finishes running"]
-    #[track_caller]
-    fn msg_build(
-        &self,
-        compiler: Compiler,
-        what: impl Display,
-        target: impl Into<Option<TargetSelection>>,
-    ) -> Option<gha::Group> {
-        self.msg(Kind::Build, compiler.stage, what, compiler.host, target)
-    }
-
     /// Return a `Group` guard for a [`Step`] that is built for each `--stage`.
     ///
     /// [`Step`]: crate::core::builder::Step
@@ -1162,20 +1151,21 @@ impl Build {
 
     #[must_use = "Groups should not be dropped until the Step finishes running"]
     #[track_caller]
-    fn msg_sysroot_tool(
+    fn msg_rustc_tool(
         &self,
         action: impl Into<Kind>,
-        stage: u32,
+        build_stage: u32,
         what: impl Display,
         host: TargetSelection,
         target: TargetSelection,
     ) -> Option<gha::Group> {
         let action = action.into().description();
         let msg = |fmt| format!("{action} {what} {fmt}");
+
         let msg = if host == target {
-            msg(format_args!("(stage{stage} -> stage{}, {target})", stage + 1))
+            msg(format_args!("(stage{build_stage} -> stage{}, {target})", build_stage + 1))
         } else {
-            msg(format_args!("(stage{stage}:{host} -> stage{}:{target})", stage + 1))
+            msg(format_args!("(stage{build_stage}:{host} -> stage{}:{target})", build_stage + 1))
         };
         self.group(&msg)
     }