Merge pull request #20268 from lnicola/sync-from-rust

minor: Sync from downstream

269 files changed, 3533 insertions, 3887 deletions

diff --git a/src/bootstrap/README.md b/src/bootstrap/README.md
index 6ce4c6d62fa..2965174b45b 100644
--- a/src/bootstrap/README.md
+++ b/src/bootstrap/README.md
@@ -105,7 +105,7 @@ build/
       debuginfo/
       ...
 
-    # Bootstrap host tools (which are always compiled with the stage0 compiler)
+    # Host tools (which are always compiled with the stage0 compiler)
     # are stored here.
     bootstrap-tools/
 
diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index d8c6be78247..40e08361a0f 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -8,6 +8,7 @@ import re
 import shutil
 import subprocess
 import sys
+import sysconfig
 import tarfile
 import tempfile
 
@@ -333,7 +334,11 @@ def default_build_triple(verbose):
         if ostype == "Android":
             kernel = "linux-android"
         else:
-            kernel = "unknown-linux-gnu"
+            python_soabi = sysconfig.get_config_var("SOABI")
+            if python_soabi is not None and "musl" in python_soabi:
+                kernel = "unknown-linux-musl"
+            else:
+                kernel = "unknown-linux-gnu"
     elif kernel == "SunOS":
         kernel = "pc-solaris"
         # On Solaris, uname -m will return a machine classification instead
diff --git a/src/bootstrap/src/core/build_steps/check.rs b/src/bootstrap/src/core/build_steps/check.rs
index 3278b55305c..f0acb7f7141 100644
--- a/src/bootstrap/src/core/build_steps/check.rs
+++ b/src/bootstrap/src/core/build_steps/check.rs
@@ -4,7 +4,10 @@ use crate::core::build_steps::compile::{
     add_to_sysroot, run_cargo, rustc_cargo, rustc_cargo_env, std_cargo, std_crates_for_run_make,
 };
 use crate::core::build_steps::tool;
-use crate::core::build_steps::tool::{COMPILETEST_ALLOW_FEATURES, SourceType, prepare_tool_cargo};
+use crate::core::build_steps::tool::{
+    COMPILETEST_ALLOW_FEATURES, SourceType, ToolTargetBuildMode, get_tool_target_compiler,
+    prepare_tool_cargo,
+};
 use crate::core::builder::{
     self, Alias, Builder, Kind, RunConfig, ShouldRun, Step, StepMetadata, crate_description,
 };
@@ -252,8 +255,10 @@ fn prepare_compiler_for_check(
     mode: Mode,
 ) -> Compiler {
     let host = builder.host_target;
+
     match mode {
         Mode::ToolBootstrap => builder.compiler(0, host),
+        Mode::ToolTarget => get_tool_target_compiler(builder, ToolTargetBuildMode::Build(target)),
         Mode::ToolStd => {
             if builder.config.compile_time_deps {
                 // When --compile-time-deps is passed, we can't use any rustc
@@ -350,7 +355,7 @@ impl Step for CodegenBackend {
         cargo
             .arg("--manifest-path")
             .arg(builder.src.join(format!("compiler/rustc_codegen_{backend}/Cargo.toml")));
-        rustc_cargo_env(builder, &mut cargo, target, build_compiler.stage);
+        rustc_cargo_env(builder, &mut cargo, target);
 
         let _guard = builder.msg_check(format!("rustc_codegen_{backend}"), target, None);
 
diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index 09bb2e35bda..c7e7b0160b1 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;
+use crate::core::build_steps::tool::{SourceType, copy_lld_artifacts};
 use crate::core::build_steps::{dist, llvm};
 use crate::core::builder;
 use crate::core::builder::{
@@ -1316,15 +1316,10 @@ pub fn rustc_cargo(
         cargo.env("RUSTC_WRAPPER", ccache);
     }
 
-    rustc_cargo_env(builder, cargo, target, build_compiler.stage);
+    rustc_cargo_env(builder, cargo, target);
 }
 
-pub fn rustc_cargo_env(
-    builder: &Builder<'_>,
-    cargo: &mut Cargo,
-    target: TargetSelection,
-    build_stage: u32,
-) {
+pub fn rustc_cargo_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelection) {
     // Set some configuration variables picked up by build scripts and
     // the compiler alike
     cargo
@@ -1379,18 +1374,24 @@ pub fn rustc_cargo_env(
         cargo.rustflag("--cfg=llvm_enzyme");
     }
 
-    // Note that this is disabled if LLVM itself is disabled or we're in a check
-    // build. If we are in a check build we still go ahead here presuming we've
-    // detected that LLVM is already built and good to go which helps prevent
-    // busting caches (e.g. like #71152).
+    // These conditionals represent a tension between three forces:
+    // - For non-check builds, we need to define some LLVM-related environment
+    //   variables, requiring LLVM to have been built.
+    // - For check builds, we want to avoid building LLVM if possible.
+    // - Check builds and non-check builds should have the same environment if
+    //   possible, to avoid unnecessary rebuilds due to cache-busting.
+    //
+    // Therefore we try to avoid building LLVM for check builds, but only if
+    // building LLVM would be expensive. If "building" LLVM is cheap
+    // (i.e. it's already built or is downloadable), we prefer to maintain a
+    // consistent environment between check and non-check builds.
     if builder.config.llvm_enabled(target) {
-        let building_is_expensive =
+        let building_llvm_is_expensive =
             crate::core::build_steps::llvm::prebuilt_llvm_config(builder, target, false)
                 .should_build();
-        // `top_stage == stage` might be false for `check --stage 1`, if we are building the stage 1 compiler
-        let can_skip_build = builder.kind == Kind::Check && builder.top_stage == build_stage;
-        let should_skip_build = building_is_expensive && can_skip_build;
-        if !should_skip_build {
+
+        let skip_llvm = (builder.kind == Kind::Check) && building_llvm_is_expensive;
+        if !skip_llvm {
             rustc_llvm_env(builder, cargo, target)
         }
     }
@@ -1407,6 +1408,9 @@ pub fn rustc_cargo_env(
 
 /// Pass down configuration from the LLVM build into the build of
 /// rustc_llvm and rustc_codegen_llvm.
+///
+/// Note that this has the side-effect of _building LLVM_, which is sometimes
+/// unwanted (e.g. for check builds).
 fn rustc_llvm_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelection) {
     if builder.config.is_rust_llvm(target) {
         cargo.env("LLVM_RUSTLLVM", "1");
@@ -1665,7 +1669,7 @@ impl Step for CodegenBackend {
         cargo
             .arg("--manifest-path")
             .arg(builder.src.join(format!("compiler/rustc_codegen_{backend}/Cargo.toml")));
-        rustc_cargo_env(builder, &mut cargo, target, compiler.stage);
+        rustc_cargo_env(builder, &mut cargo, target);
 
         // Ideally, we'd have a separate step for the individual codegen backends,
         // like we have in tests (test::CodegenGCC) but that would require a lot of restructuring.
@@ -2050,19 +2054,20 @@ impl Step for Assemble {
             }
         }
 
-        let maybe_install_llvm_bitcode_linker = |compiler| {
+        let maybe_install_llvm_bitcode_linker = || {
             if builder.config.llvm_bitcode_linker_enabled {
                 trace!("llvm-bitcode-linker enabled, installing");
-                let llvm_bitcode_linker =
-                    builder.ensure(crate::core::build_steps::tool::LlvmBitcodeLinker {
-                        build_compiler: compiler,
-                        target: target_compiler.host,
-                    });
+                let llvm_bitcode_linker = builder.ensure(
+                    crate::core::build_steps::tool::LlvmBitcodeLinker::from_target_compiler(
+                        builder,
+                        target_compiler,
+                    ),
+                );
 
                 // Copy the llvm-bitcode-linker to the self-contained binary directory
                 let bindir_self_contained = builder
-                    .sysroot(compiler)
-                    .join(format!("lib/rustlib/{}/bin/self-contained", compiler.host));
+                    .sysroot(target_compiler)
+                    .join(format!("lib/rustlib/{}/bin/self-contained", target_compiler.host));
                 let tool_exe = exe("llvm-bitcode-linker", target_compiler.host);
 
                 t!(fs::create_dir_all(&bindir_self_contained));
@@ -2089,9 +2094,9 @@ impl Step for Assemble {
                 builder.info(&format!("Creating a sysroot for stage{stage} compiler (use `rustup toolchain link 'name' build/host/stage{stage}`)", stage = target_compiler.stage));
             }
 
-            let mut precompiled_compiler = target_compiler;
-            precompiled_compiler.forced_compiler(true);
-            maybe_install_llvm_bitcode_linker(precompiled_compiler);
+            // FIXME: this is incomplete, we do not copy a bunch of other stuff to the downloaded
+            // sysroot...
+            maybe_install_llvm_bitcode_linker();
 
             return target_compiler;
         }
@@ -2256,10 +2261,12 @@ impl Step for Assemble {
         copy_codegen_backends_to_sysroot(builder, build_compiler, target_compiler);
 
         if builder.config.lld_enabled {
-            builder.ensure(crate::core::build_steps::tool::LldWrapper {
-                build_compiler,
-                target_compiler,
-            });
+            let lld_wrapper =
+                builder.ensure(crate::core::build_steps::tool::LldWrapper::for_use_by_compiler(
+                    builder,
+                    target_compiler,
+                ));
+            copy_lld_artifacts(builder, lld_wrapper, target_compiler);
         }
 
         if builder.config.llvm_enabled(target_compiler.host) && builder.config.llvm_tools_enabled {
@@ -2284,15 +2291,14 @@ impl Step for Assemble {
         }
 
         // In addition to `rust-lld` also install `wasm-component-ld` when
-        // LLD is enabled. This is a relatively small binary that primarily
-        // delegates to the `rust-lld` binary for linking and then runs
-        // logic to create the final binary. This is used by the
-        // `wasm32-wasip2` target of Rust.
+        // is enabled. This is used by the `wasm32-wasip2` target of Rust.
         if builder.tool_enabled("wasm-component-ld") {
-            let wasm_component = builder.ensure(crate::core::build_steps::tool::WasmComponentLd {
-                compiler: build_compiler,
-                target: target_compiler.host,
-            });
+            let wasm_component = builder.ensure(
+                crate::core::build_steps::tool::WasmComponentLd::for_use_by_compiler(
+                    builder,
+                    target_compiler,
+                ),
+            );
             builder.copy_link(
                 &wasm_component.tool_path,
                 &libdir_bin.join(wasm_component.tool_path.file_name().unwrap()),
@@ -2300,7 +2306,7 @@ impl Step for Assemble {
             );
         }
 
-        maybe_install_llvm_bitcode_linker(target_compiler);
+        maybe_install_llvm_bitcode_linker();
 
         // Ensure that `libLLVM.so` ends up in the newly build compiler directory,
         // so that it can be found when the newly built `rustc` is run.
diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index 8b2d65ace50..39e4fb2ac01 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -1575,7 +1575,10 @@ impl Step for Extended {
             compiler: builder.compiler(stage, target),
             backend: "cranelift".to_string(),
         });
-        add_component!("llvm-bitcode-linker" => LlvmBitcodeLinker {compiler, target});
+        add_component!("llvm-bitcode-linker" => LlvmBitcodeLinker {
+            build_compiler: compiler,
+            target
+        });
 
         let etc = builder.src.join("src/etc/installer");
 
@@ -2341,9 +2344,13 @@ impl Step for LlvmTools {
     }
 }
 
+/// Distributes the `llvm-bitcode-linker` tool so that it can be used by a compiler whose host
+/// is `target`.
 #[derive(Debug, PartialOrd, Ord, Clone, Hash, PartialEq, Eq)]
 pub struct LlvmBitcodeLinker {
-    pub compiler: Compiler,
+    /// The linker will be compiled by this compiler.
+    pub build_compiler: Compiler,
+    /// The linker will by usable by rustc on this host.
     pub target: TargetSelection,
 }
 
@@ -2359,9 +2366,8 @@ impl Step for LlvmBitcodeLinker {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(LlvmBitcodeLinker {
-            compiler: run.builder.compiler_for(
-                run.builder.top_stage,
-                run.builder.config.host_target,
+            build_compiler: tool::LlvmBitcodeLinker::get_build_compiler_for_target(
+                run.builder,
                 run.target,
             ),
             target: run.target,
@@ -2369,13 +2375,10 @@ impl Step for LlvmBitcodeLinker {
     }
 
     fn run(self, builder: &Builder<'_>) -> Option<GeneratedTarball> {
-        let compiler = self.compiler;
         let target = self.target;
 
-        builder.ensure(compile::Rustc::new(compiler, target));
-
-        let llbc_linker =
-            builder.ensure(tool::LlvmBitcodeLinker { build_compiler: compiler, target });
+        let llbc_linker = builder
+            .ensure(tool::LlvmBitcodeLinker::from_build_compiler(self.build_compiler, target));
 
         let self_contained_bin_dir = format!("lib/rustlib/{}/bin/self-contained", target.triple);
 
diff --git a/src/bootstrap/src/core/build_steps/gcc.rs b/src/bootstrap/src/core/build_steps/gcc.rs
index 899e3fd9a45..d4cbbe60921 100644
--- a/src/bootstrap/src/core/build_steps/gcc.rs
+++ b/src/bootstrap/src/core/build_steps/gcc.rs
@@ -220,21 +220,18 @@ fn build_gcc(metadata: &Meta, builder: &Builder<'_>, target: TargetSelection) {
     t!(fs::create_dir_all(install_dir));
 
     // GCC creates files (e.g. symlinks to the downloaded dependencies)
-    // in the source directory, which does not work with our CI setup, where we mount
+    // in the source directory, which does not work with our CI/Docker setup, where we mount
     // source directories as read-only on Linux.
-    // Therefore, as a part of the build in CI, we first copy the whole source directory
-    // to the build directory, and perform the build from there.
-    let src_dir = if builder.config.is_running_on_ci {
-        let src_dir = builder.gcc_out(target).join("src");
-        if src_dir.exists() {
-            builder.remove_dir(&src_dir);
-        }
-        builder.create_dir(&src_dir);
-        builder.cp_link_r(root, &src_dir);
-        src_dir
-    } else {
-        root.clone()
-    };
+    // And in general, we shouldn't be modifying the source directories if possible, even for local
+    // builds.
+    // Therefore, we first copy the whole source directory to the build directory, and perform the
+    // build from there.
+    let src_dir = builder.gcc_out(target).join("src");
+    if src_dir.exists() {
+        builder.remove_dir(&src_dir);
+    }
+    builder.create_dir(&src_dir);
+    builder.cp_link_r(root, &src_dir);
 
     command(src_dir.join("contrib/download_prerequisites")).current_dir(&src_dir).run(builder);
     let mut configure_cmd = command(src_dir.join("configure"));
diff --git a/src/bootstrap/src/core/build_steps/install.rs b/src/bootstrap/src/core/build_steps/install.rs
index 4434d6658eb..4156b49a8b3 100644
--- a/src/bootstrap/src/core/build_steps/install.rs
+++ b/src/bootstrap/src/core/build_steps/install.rs
@@ -287,7 +287,7 @@ install!((self, builder, _config),
         }
     };
     LlvmBitcodeLinker, alias = "llvm-bitcode-linker", Self::should_build(_config), only_hosts: true, {
-        if let Some(tarball) = builder.ensure(dist::LlvmBitcodeLinker { compiler: self.compiler, target: self.target }) {
+        if let Some(tarball) = builder.ensure(dist::LlvmBitcodeLinker { build_compiler: self.compiler, target: self.target }) {
             install_sh(builder, "llvm-bitcode-linker", self.compiler.stage, Some(self.target), &tarball);
         } else {
             builder.info(
diff --git a/src/bootstrap/src/core/build_steps/mod.rs b/src/bootstrap/src/core/build_steps/mod.rs
index fcb6abea434..c2ad9a4df59 100644
--- a/src/bootstrap/src/core/build_steps/mod.rs
+++ b/src/bootstrap/src/core/build_steps/mod.rs
@@ -11,7 +11,6 @@ pub(crate) mod llvm;
 pub(crate) mod perf;
 pub(crate) mod run;
 pub(crate) mod setup;
-pub(crate) mod suggest;
 pub(crate) mod synthetic_targets;
 pub(crate) mod test;
 pub(crate) mod tool;
diff --git a/src/bootstrap/src/core/build_steps/suggest.rs b/src/bootstrap/src/core/build_steps/suggest.rs
deleted file mode 100644
index fd4918961ad..00000000000
--- a/src/bootstrap/src/core/build_steps/suggest.rs
+++ /dev/null
@@ -1,68 +0,0 @@
-//! Attempt to magically identify good tests to run
-
-use std::path::PathBuf;
-use std::str::FromStr;
-
-use clap::Parser;
-
-use crate::core::build_steps::tool::Tool;
-use crate::core::builder::Builder;
-
-/// Suggests a list of possible `x.py` commands to run based on modified files in branch.
-pub fn suggest(builder: &Builder<'_>, run: bool) {
-    let git_config = builder.config.git_config();
-    let suggestions = builder
-        .tool_cmd(Tool::SuggestTests)
-        .env("SUGGEST_TESTS_NIGHTLY_BRANCH", git_config.nightly_branch)
-        .env("SUGGEST_TESTS_MERGE_COMMIT_EMAIL", git_config.git_merge_commit_email)
-        .run_capture_stdout(builder)
-        .stdout();
-
-    let suggestions = suggestions
-        .lines()
-        .map(|line| {
-            let mut sections = line.split_ascii_whitespace();
-
-            // this code expects one suggestion per line in the following format:
-            // <x_subcommand> {some number of flags} [optional stage number]
-            let cmd = sections.next().unwrap();
-            let stage = sections.next_back().and_then(|s| str::parse(s).ok());
-            let paths: Vec<PathBuf> = sections.map(|p| PathBuf::from_str(p).unwrap()).collect();
-
-            (cmd, stage, paths)
-        })
-        .collect::<Vec<_>>();
-
-    if !suggestions.is_empty() {
-        println!("==== SUGGESTIONS ====");
-        for sug in &suggestions {
-            print!("x {} ", sug.0);
-            if let Some(stage) = sug.1 {
-                print!("--stage {stage} ");
-            }
-
-            for path in &sug.2 {
-                print!("{} ", path.display());
-            }
-            println!();
-        }
-        println!("=====================");
-    } else {
-        println!("No suggestions found!");
-        return;
-    }
-
-    if run {
-        for sug in suggestions {
-            let mut build: crate::Build = builder.build.clone();
-            build.config.paths = sug.2;
-            build.config.cmd = crate::core::config::flags::Flags::parse_from(["x.py", sug.0]).cmd;
-            if let Some(stage) = sug.1 {
-                build.config.stage = stage;
-            }
-            build.build();
-        }
-    } else {
-        println!("HELP: consider using the `--run` flag to automatically run suggested tests");
-    }
-}
diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index 757eac1475c..7652ea1a488 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -47,12 +47,11 @@ impl Step for CrateBootstrap {
     const DEFAULT: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        // This step is responsible for several different tool paths. By default
-        // it will test all of them, but requesting specific tools on the
-        // command-line (e.g. `./x test suggest-tests`) will test only the
-        // specified tools.
+        // This step is responsible for several different tool paths.
+        //
+        // By default, it will test all of them, but requesting specific tools on the command-line
+        // (e.g. `./x test src/tools/coverage-dump`) will test only the specified tools.
         run.path("src/tools/jsondoclint")
-            .path("src/tools/suggest-tests")
             .path("src/tools/replace-version-placeholder")
             .path("src/tools/coverage-dump")
             // We want `./x test tidy` to _run_ the tidy tool, not its tests.
@@ -1758,6 +1757,10 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         cmd.arg("--host").arg(&*compiler.host.triple);
         cmd.arg("--llvm-filecheck").arg(builder.llvm_filecheck(builder.config.host_target));
 
+        if let Some(codegen_backend) = builder.config.default_codegen_backend(compiler.host) {
+            cmd.arg("--codegen-backend").arg(&codegen_backend);
+        }
+
         if builder.build.config.llvm_enzyme {
             cmd.arg("--has-enzyme");
         }
@@ -1811,7 +1814,24 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         }
 
         let mut flags = if is_rustdoc { Vec::new() } else { vec!["-Crpath".to_string()] };
-        flags.push(format!("-Cdebuginfo={}", builder.config.rust_debuginfo_level_tests));
+        flags.push(format!(
+            "-Cdebuginfo={}",
+            if suite == "codegen" {
+                // codegen tests typically check LLVM IR and are sensitive to additional debuginfo.
+                // So do not apply `rust.debuginfo-level-tests` for codegen tests.
+                if builder.config.rust_debuginfo_level_tests
+                    != crate::core::config::DebuginfoLevel::None
+                {
+                    println!(
+                        "NOTE: ignoring `rust.debuginfo-level-tests={}` for codegen tests",
+                        builder.config.rust_debuginfo_level_tests
+                    );
+                }
+                crate::core::config::DebuginfoLevel::None
+            } else {
+                builder.config.rust_debuginfo_level_tests
+            }
+        ));
         flags.extend(builder.config.cmd.compiletest_rustc_args().iter().map(|s| s.to_string()));
 
         if suite != "mir-opt" {
@@ -2946,7 +2966,8 @@ impl Step for RemoteCopyLibs {
 
         builder.info(&format!("REMOTE copy libs to emulator ({target})"));
 
-        let remote_test_server = builder.ensure(tool::RemoteTestServer { compiler, target });
+        let remote_test_server =
+            builder.ensure(tool::RemoteTestServer { build_compiler: compiler, target });
 
         // Spawn the emulator and wait for it to come online
         let tool = builder.tool_exe(Tool::RemoteTestClient);
@@ -3387,7 +3408,7 @@ impl Step for CodegenCranelift {
             cargo
                 .arg("--manifest-path")
                 .arg(builder.src.join("compiler/rustc_codegen_cranelift/build_system/Cargo.toml"));
-            compile::rustc_cargo_env(builder, &mut cargo, target, compiler.stage);
+            compile::rustc_cargo_env(builder, &mut cargo, target);
 
             // Avoid incremental cache issues when changing rustc
             cargo.env("CARGO_BUILD_INCREMENTAL", "false");
@@ -3519,7 +3540,7 @@ impl Step for CodegenGCC {
             cargo
                 .arg("--manifest-path")
                 .arg(builder.src.join("compiler/rustc_codegen_gcc/build_system/Cargo.toml"));
-            compile::rustc_cargo_env(builder, &mut cargo, target, compiler.stage);
+            compile::rustc_cargo_env(builder, &mut cargo, target);
             add_cg_gcc_cargo_flags(&mut cargo, &gcc);
 
             // Avoid incremental cache issues when changing rustc
diff --git a/src/bootstrap/src/core/build_steps/tool.rs b/src/bootstrap/src/core/build_steps/tool.rs
index 814a44b9a13..f5fa33b98f3 100644
--- a/src/bootstrap/src/core/build_steps/tool.rs
+++ b/src/bootstrap/src/core/build_steps/tool.rs
@@ -42,7 +42,8 @@ pub enum ToolArtifactKind {
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 struct ToolBuild {
-    compiler: Compiler,
+    /// Compiler that will build this tool.
+    build_compiler: Compiler,
     target: TargetSelection,
     tool: &'static str,
     path: &'static str,
@@ -112,34 +113,34 @@ impl Step for ToolBuild {
         let mut tool = self.tool;
         let path = self.path;
 
-        let target_compiler = self.compiler;
-        self.compiler = if self.mode == Mode::ToolRustc {
-            get_tool_rustc_compiler(builder, self.compiler)
+        let target_compiler = self.build_compiler;
+        self.build_compiler = if self.mode == Mode::ToolRustc {
+            get_tool_rustc_compiler(builder, self.build_compiler)
         } else {
-            self.compiler
+            self.build_compiler
         };
 
         match self.mode {
             Mode::ToolRustc => {
                 // If compiler was forced, its artifacts should have been prepared earlier.
-                if !self.compiler.is_forced_compiler() {
-                    builder.std(self.compiler, self.compiler.host);
-                    builder.ensure(compile::Rustc::new(self.compiler, target));
+                if !self.build_compiler.is_forced_compiler() {
+                    builder.std(self.build_compiler, self.build_compiler.host);
+                    builder.ensure(compile::Rustc::new(self.build_compiler, target));
                 }
             }
             Mode::ToolStd => {
                 // If compiler was forced, its artifacts should have been prepared earlier.
-                if !self.compiler.is_forced_compiler() {
-                    builder.std(self.compiler, target)
+                if !self.build_compiler.is_forced_compiler() {
+                    builder.std(self.build_compiler, target);
                 }
             }
-            Mode::ToolBootstrap => {} // uses downloaded stage0 compiler libs
+            Mode::ToolBootstrap | Mode::ToolTarget => {} // uses downloaded stage0 compiler libs
             _ => panic!("unexpected Mode for tool build"),
         }
 
         let mut cargo = prepare_tool_cargo(
             builder,
-            self.compiler,
+            self.build_compiler,
             self.mode,
             target,
             Kind::Build,
@@ -161,7 +162,7 @@ impl Step for ToolBuild {
 
         // Rustc tools (miri, clippy, cargo, rustfmt, rust-analyzer)
         // could use the additional optimizations.
-        if self.mode == Mode::ToolRustc && is_lto_stage(&self.compiler) {
+        if self.mode == Mode::ToolRustc && is_lto_stage(&self.build_compiler) {
             let lto = match builder.config.rust_lto {
                 RustcLto::Off => Some("off"),
                 RustcLto::Thin => Some("thin"),
@@ -183,8 +184,9 @@ impl Step for ToolBuild {
             Kind::Build,
             self.mode,
             self.tool,
-            self.compiler.stage,
-            &self.compiler.host,
+            // A stage N tool is built with the stage N-1 compiler.
+            self.build_compiler.stage + 1,
+            &self.build_compiler.host,
             &self.target,
         );
 
@@ -207,14 +209,14 @@ impl Step for ToolBuild {
             }
             let tool_path = match self.artifact_kind {
                 ToolArtifactKind::Binary => {
-                    copy_link_tool_bin(builder, self.compiler, self.target, self.mode, tool)
+                    copy_link_tool_bin(builder, self.build_compiler, self.target, self.mode, tool)
                 }
                 ToolArtifactKind::Library => builder
-                    .cargo_out(self.compiler, self.mode, self.target)
+                    .cargo_out(self.build_compiler, self.mode, self.target)
                     .join(format!("lib{tool}.rlib")),
             };
 
-            ToolBuildResult { tool_path, build_compiler: self.compiler, target_compiler }
+            ToolBuildResult { tool_path, build_compiler: self.build_compiler, target_compiler }
         }
     }
 }
@@ -365,6 +367,47 @@ pub(crate) fn get_tool_rustc_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 {
+    /// Build the tool using rustc that corresponds to the selected CLI stage.
+    Build(TargetSelection),
+    /// Build the tool so that it can be attached to the sysroot of the passed compiler.
+    /// Since we always dist stage 2+, the compiler that builds the tool in this case has to be
+    /// stage 1+.
+    Dist(Compiler),
+}
+
+/// Returns compiler that is able to compile a `ToolTarget` tool with the given `mode`.
+pub(crate) fn get_tool_target_compiler(
+    builder: &Builder<'_>,
+    mode: ToolTargetBuildMode,
+) -> Compiler {
+    let (target, build_compiler_stage) = match mode {
+        ToolTargetBuildMode::Build(target) => {
+            assert!(builder.top_stage > 0);
+            // If we want to build a stage N tool, we need to compile it with stage N-1 rustc
+            (target, builder.top_stage - 1)
+        }
+        ToolTargetBuildMode::Dist(target_compiler) => {
+            assert!(target_compiler.stage > 0);
+            // If we want to dist a stage N rustc, we want to attach stage N tool to it.
+            // And to build that tool, we need to compile it with stage N-1 rustc
+            (target_compiler.host, target_compiler.stage - 1)
+        }
+    };
+
+    let compiler = if builder.host_target == target {
+        builder.compiler(build_compiler_stage, builder.host_target)
+    } else {
+        // If we are cross-compiling a stage 1 tool, we cannot do that with a stage 0 compiler,
+        // so we auto-bump the tool's stage to 2, which means we need a stage 1 compiler.
+        builder.compiler(build_compiler_stage.max(1), builder.host_target)
+    };
+    builder.std(compiler, target);
+    compiler
+}
+
 /// Links a built tool binary with the given `name` from the build directory to the
 /// tools directory.
 fn copy_link_tool_bin(
@@ -451,7 +494,7 @@ macro_rules! bootstrap_tool {
                 let compiletest_wants_stage0 = $tool_name == "compiletest" && builder.config.compiletest_use_stage0_libtest;
 
                 builder.ensure(ToolBuild {
-                    compiler: self.compiler,
+                    build_compiler: self.compiler,
                     target: self.target,
                     tool: $tool_name,
                     mode: if is_unstable && !compiletest_wants_stage0 {
@@ -517,12 +560,10 @@ bootstrap_tool!(
     ReplaceVersionPlaceholder, "src/tools/replace-version-placeholder", "replace-version-placeholder";
     CollectLicenseMetadata, "src/tools/collect-license-metadata", "collect-license-metadata";
     GenerateCopyright, "src/tools/generate-copyright", "generate-copyright";
-    SuggestTests, "src/tools/suggest-tests", "suggest-tests";
     GenerateWindowsSys, "src/tools/generate-windows-sys", "generate-windows-sys";
     // rustdoc-gui-test has a crate dependency on compiletest, so it needs the same unstable features.
     RustdocGUITest, "src/tools/rustdoc-gui-test", "rustdoc-gui-test", is_unstable_tool = true, allow_features = COMPILETEST_ALLOW_FEATURES;
     CoverageDump, "src/tools/coverage-dump", "coverage-dump";
-    WasmComponentLd, "src/tools/wasm-component-ld", "wasm-component-ld", is_unstable_tool = true, allow_features = "min_specialization";
     UnicodeTableGenerator, "src/tools/unicode-table-generator", "unicode-table-generator";
     FeaturesStatusDump, "src/tools/features-status-dump", "features-status-dump";
     OptimizedDist, "src/tools/opt-dist", "opt-dist", submodules = &["src/tools/rustc-perf"];
@@ -561,7 +602,7 @@ impl Step for RustcPerf {
         builder.require_submodule("src/tools/rustc-perf", None);
 
         let tool = ToolBuild {
-            compiler: self.compiler,
+            build_compiler: self.compiler,
             target: self.target,
             tool: "collector",
             mode: Mode::ToolBootstrap,
@@ -577,7 +618,7 @@ impl Step for RustcPerf {
         let res = builder.ensure(tool.clone());
         // We also need to symlink the `rustc-fake` binary to the corresponding directory,
         // because `collector` expects it in the same directory.
-        copy_link_tool_bin(builder, tool.compiler, tool.target, tool.mode, "rustc-fake");
+        copy_link_tool_bin(builder, tool.build_compiler, tool.target, tool.mode, "rustc-fake");
 
         res
     }
@@ -621,7 +662,7 @@ impl Step for ErrorIndex {
 
     fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
         builder.ensure(ToolBuild {
-            compiler: self.compiler,
+            build_compiler: self.compiler,
             target: self.compiler.host,
             tool: "error_index_generator",
             mode: Mode::ToolRustc,
@@ -637,7 +678,7 @@ impl Step for ErrorIndex {
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct RemoteTestServer {
-    pub compiler: Compiler,
+    pub build_compiler: Compiler,
     pub target: TargetSelection,
 }
 
@@ -650,17 +691,20 @@ impl Step for RemoteTestServer {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(RemoteTestServer {
-            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,
         });
     }
 
     fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
         builder.ensure(ToolBuild {
-            compiler: self.compiler,
+            build_compiler: self.build_compiler,
             target: self.target,
             tool: "remote-test-server",
-            mode: Mode::ToolStd,
+            mode: Mode::ToolTarget,
             path: "src/tools/remote-test-server",
             source_type: SourceType::InTree,
             extra_features: Vec::new(),
@@ -669,6 +713,10 @@ impl Step for RemoteTestServer {
             artifact_kind: ToolArtifactKind::Binary,
         })
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::build("remote-test-server", self.target).built_by(self.build_compiler))
+    }
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
@@ -758,7 +806,7 @@ impl Step for Rustdoc {
 
         let ToolBuildResult { tool_path, build_compiler, target_compiler } =
             builder.ensure(ToolBuild {
-                compiler: target_compiler,
+                build_compiler: target_compiler,
                 target,
                 // Cargo adds a number of paths to the dylib search path on windows, which results in
                 // the wrong rustdoc being executed. To avoid the conflicting rustdocs, we name the "tool"
@@ -826,7 +874,7 @@ impl Step for Cargo {
         builder.build.require_submodule("src/tools/cargo", None);
 
         builder.ensure(ToolBuild {
-            compiler: self.compiler,
+            build_compiler: self.compiler,
             target: self.target,
             tool: "cargo",
             mode: Mode::ToolRustc,
@@ -840,17 +888,50 @@ impl Step for Cargo {
     }
 }
 
+/// Represents a built LldWrapper, the `lld-wrapper` tool itself, and a directory
+/// containing a build of LLD.
+#[derive(Clone)]
+pub struct BuiltLldWrapper {
+    tool: ToolBuildResult,
+    lld_dir: PathBuf,
+}
+
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct LldWrapper {
     pub build_compiler: Compiler,
-    pub target_compiler: Compiler,
+    pub target: TargetSelection,
+}
+
+impl LldWrapper {
+    /// Returns `LldWrapper` that should be **used** by the passed compiler.
+    pub fn for_use_by_compiler(builder: &Builder<'_>, target_compiler: Compiler) -> Self {
+        Self {
+            build_compiler: get_tool_target_compiler(
+                builder,
+                ToolTargetBuildMode::Dist(target_compiler),
+            ),
+            target: target_compiler.host,
+        }
+    }
 }
 
 impl Step for LldWrapper {
-    type Output = ToolBuildResult;
+    type Output = BuiltLldWrapper;
+
+    const ONLY_HOSTS: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        run.never()
+        run.path("src/tools/lld-wrapper")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(LldWrapper {
+            build_compiler: get_tool_target_compiler(
+                run.builder,
+                ToolTargetBuildMode::Build(run.target),
+            ),
+            target: run.target,
+        });
     }
 
     #[cfg_attr(
@@ -859,25 +940,16 @@ impl Step for LldWrapper {
             level = "debug",
             name = "LldWrapper::run",
             skip_all,
-            fields(build_compiler = ?self.build_compiler, target_compiler = ?self.target_compiler),
+            fields(build_compiler = ?self.build_compiler),
         ),
     )]
-    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
-        if builder.config.dry_run() {
-            return ToolBuildResult {
-                tool_path: Default::default(),
-                build_compiler: self.build_compiler,
-                target_compiler: self.target_compiler,
-            };
-        }
-
-        let target = self.target_compiler.host;
-
-        let tool_result = builder.ensure(ToolBuild {
-            compiler: self.build_compiler,
-            target,
+    fn run(self, builder: &Builder<'_>) -> Self::Output {
+        let lld_dir = builder.ensure(llvm::Lld { target: self.target });
+        let tool = builder.ensure(ToolBuild {
+            build_compiler: self.build_compiler,
+            target: self.target,
             tool: "lld-wrapper",
-            mode: Mode::ToolStd,
+            mode: Mode::ToolTarget,
             path: "src/tools/lld-wrapper",
             source_type: SourceType::InTree,
             extra_features: Vec::new(),
@@ -885,38 +957,110 @@ impl Step for LldWrapper {
             cargo_args: Vec::new(),
             artifact_kind: ToolArtifactKind::Binary,
         });
+        BuiltLldWrapper { tool, lld_dir }
+    }
 
-        let libdir_bin = builder.sysroot_target_bindir(self.target_compiler, target);
-        t!(fs::create_dir_all(&libdir_bin));
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::build("LldWrapper", self.target).built_by(self.build_compiler))
+    }
+}
 
-        let lld_install = builder.ensure(llvm::Lld { target });
-        let src_exe = exe("lld", target);
-        let dst_exe = exe("rust-lld", target);
+pub(crate) fn copy_lld_artifacts(
+    builder: &Builder<'_>,
+    lld_wrapper: BuiltLldWrapper,
+    target_compiler: Compiler,
+) {
+    let target = target_compiler.host;
 
+    let libdir_bin = builder.sysroot_target_bindir(target_compiler, target);
+    t!(fs::create_dir_all(&libdir_bin));
+
+    let src_exe = exe("lld", target);
+    let dst_exe = exe("rust-lld", target);
+
+    builder.copy_link(
+        &lld_wrapper.lld_dir.join("bin").join(src_exe),
+        &libdir_bin.join(dst_exe),
+        FileType::Executable,
+    );
+    let self_contained_lld_dir = libdir_bin.join("gcc-ld");
+    t!(fs::create_dir_all(&self_contained_lld_dir));
+
+    for name in crate::LLD_FILE_NAMES {
         builder.copy_link(
-            &lld_install.join("bin").join(src_exe),
-            &libdir_bin.join(dst_exe),
+            &lld_wrapper.tool.tool_path,
+            &self_contained_lld_dir.join(exe(name, target)),
             FileType::Executable,
         );
-        let self_contained_lld_dir = libdir_bin.join("gcc-ld");
-        t!(fs::create_dir_all(&self_contained_lld_dir));
-
-        for name in crate::LLD_FILE_NAMES {
-            builder.copy_link(
-                &tool_result.tool_path,
-                &self_contained_lld_dir.join(exe(name, target)),
-                FileType::Executable,
-            );
+    }
+}
+
+/// Builds the `wasm-component-ld` linker wrapper, which is shipped with rustc to be executed on the
+/// host platform where rustc runs.
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
+pub struct WasmComponentLd {
+    build_compiler: Compiler,
+    target: TargetSelection,
+}
+
+impl WasmComponentLd {
+    /// Returns `WasmComponentLd` that should be **used** by the passed compiler.
+    pub fn for_use_by_compiler(builder: &Builder<'_>, target_compiler: Compiler) -> Self {
+        Self {
+            build_compiler: get_tool_target_compiler(
+                builder,
+                ToolTargetBuildMode::Dist(target_compiler),
+            ),
+            target: target_compiler.host,
         }
+    }
+}
+
+impl Step for WasmComponentLd {
+    type Output = ToolBuildResult;
+
+    const ONLY_HOSTS: bool = true;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("src/tools/wasm-component-ld")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(WasmComponentLd {
+            build_compiler: get_tool_target_compiler(
+                run.builder,
+                ToolTargetBuildMode::Build(run.target),
+            ),
+            target: run.target,
+        });
+    }
 
-        tool_result
+    #[cfg_attr(
+        feature = "tracing",
+        instrument(
+            level = "debug",
+            name = "WasmComponentLd::run",
+            skip_all,
+            fields(build_compiler = ?self.build_compiler),
+        ),
+    )]
+    fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
+        builder.ensure(ToolBuild {
+            build_compiler: self.build_compiler,
+            target: self.target,
+            tool: "wasm-component-ld",
+            mode: Mode::ToolTarget,
+            path: "src/tools/wasm-component-ld",
+            source_type: SourceType::InTree,
+            extra_features: vec![],
+            allow_features: "",
+            cargo_args: vec![],
+            artifact_kind: ToolArtifactKind::Binary,
+        })
     }
 
     fn metadata(&self) -> Option<StepMetadata> {
-        Some(
-            StepMetadata::build("LldWrapper", self.target_compiler.host)
-                .built_by(self.build_compiler),
-        )
+        Some(StepMetadata::build("WasmComponentLd", self.target).built_by(self.build_compiler))
     }
 }
 
@@ -949,7 +1093,7 @@ impl Step for RustAnalyzer {
 
     fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
         builder.ensure(ToolBuild {
-            compiler: self.compiler,
+            build_compiler: self.compiler,
             target: self.target,
             tool: "rust-analyzer",
             mode: Mode::ToolRustc,
@@ -994,7 +1138,7 @@ impl Step for RustAnalyzerProcMacroSrv {
 
     fn run(self, builder: &Builder<'_>) -> Option<ToolBuildResult> {
         let tool_result = builder.ensure(ToolBuild {
-            compiler: self.compiler,
+            build_compiler: self.compiler,
             target: self.target,
             tool: "rust-analyzer-proc-macro-srv",
             mode: Mode::ToolRustc,
@@ -1022,8 +1166,35 @@ impl Step for RustAnalyzerProcMacroSrv {
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct LlvmBitcodeLinker {
-    pub build_compiler: Compiler,
-    pub target: TargetSelection,
+    build_compiler: Compiler,
+    target: TargetSelection,
+}
+
+impl LlvmBitcodeLinker {
+    /// Returns `LlvmBitcodeLinker` 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 }
+    }
+
+    /// Returns `LlvmBitcodeLinker` that should be **used** by the passed compiler.
+    pub fn from_target_compiler(builder: &Builder<'_>, target_compiler: Compiler) -> Self {
+        Self {
+            build_compiler: get_tool_target_compiler(
+                builder,
+                ToolTargetBuildMode::Dist(target_compiler),
+            ),
+            target: target_compiler.host,
+        }
+    }
+
+    /// Return a compiler that is able to build this tool for the given `target`.
+    pub fn get_build_compiler_for_target(
+        builder: &Builder<'_>,
+        target: TargetSelection,
+    ) -> Compiler {
+        get_tool_target_compiler(builder, ToolTargetBuildMode::Build(target))
+    }
 }
 
 impl Step for LlvmBitcodeLinker {
@@ -1039,9 +1210,7 @@ impl Step for LlvmBitcodeLinker {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(LlvmBitcodeLinker {
-            build_compiler: run
-                .builder
-                .compiler(run.builder.top_stage, run.builder.config.host_target),
+            build_compiler: Self::get_build_compiler_for_target(run.builder, run.target),
             target: run.target,
         });
     }
@@ -1052,10 +1221,10 @@ impl Step for LlvmBitcodeLinker {
     )]
     fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
         builder.ensure(ToolBuild {
-            compiler: self.build_compiler,
+            build_compiler: self.build_compiler,
             target: self.target,
             tool: "llvm-bitcode-linker",
-            mode: Mode::ToolRustc,
+            mode: Mode::ToolTarget,
             path: "src/tools/llvm-bitcode-linker",
             source_type: SourceType::InTree,
             extra_features: vec![],
@@ -1240,7 +1409,7 @@ fn run_tool_build_step(
 
     let ToolBuildResult { tool_path, build_compiler, target_compiler } =
         builder.ensure(ToolBuild {
-            compiler,
+            build_compiler: compiler,
             target,
             tool: tool_name,
             mode: Mode::ToolRustc,
@@ -1339,7 +1508,7 @@ impl Step for TestFloatParse {
         let compiler = builder.compiler(builder.top_stage, bootstrap_host);
 
         builder.ensure(ToolBuild {
-            compiler,
+            build_compiler: compiler,
             target: bootstrap_host,
             tool: "test-float-parse",
             mode: Mode::ToolStd,
diff --git a/src/bootstrap/src/core/builder/cargo.rs b/src/bootstrap/src/core/builder/cargo.rs
index d5a290d804c..badd5f24dba 100644
--- a/src/bootstrap/src/core/builder/cargo.rs
+++ b/src/bootstrap/src/core/builder/cargo.rs
@@ -113,7 +113,7 @@ impl Cargo {
 
         match cmd_kind {
             // No need to configure the target linker for these command types.
-            Kind::Clean | Kind::Check | Kind::Suggest | Kind::Format | Kind::Setup => {}
+            Kind::Clean | Kind::Check | Kind::Format | Kind::Setup => {}
             _ => {
                 cargo.configure_linker(builder, mode);
             }
@@ -537,7 +537,7 @@ impl Builder<'_> {
             }
         }
 
-        let stage = if compiler.stage == 0 && self.local_rebuild {
+        let build_compiler_stage = if compiler.stage == 0 && self.local_rebuild {
             // Assume the local-rebuild rustc already has stage1 features.
             1
         } else {
@@ -545,15 +545,17 @@ impl Builder<'_> {
         };
 
         // We synthetically interpret a stage0 compiler used to build tools as a
-        // "raw" compiler in that it's the exact snapshot we download. Normally
-        // the stage0 build means it uses libraries build by the stage0
-        // compiler, but for tools we just use the precompiled libraries that
-        // we've downloaded
-        let use_snapshot = mode == Mode::ToolBootstrap;
-        assert!(!use_snapshot || stage == 0 || self.local_rebuild);
-
-        let maybe_sysroot = self.sysroot(compiler);
-        let sysroot = if use_snapshot { self.rustc_snapshot_sysroot() } else { &maybe_sysroot };
+        // "raw" compiler in that it's the exact snapshot we download. For things like
+        // ToolRustc, we would have to use the artificial stage0-sysroot compiler instead.
+        let use_snapshot =
+            mode == Mode::ToolBootstrap || (mode == Mode::ToolTarget && build_compiler_stage == 0);
+        assert!(!use_snapshot || build_compiler_stage == 0 || self.local_rebuild);
+
+        let sysroot = if use_snapshot {
+            self.rustc_snapshot_sysroot().to_path_buf()
+        } else {
+            self.sysroot(compiler)
+        };
         let libdir = self.rustc_libdir(compiler);
 
         let sysroot_str = sysroot.as_os_str().to_str().expect("sysroot should be UTF-8");
@@ -562,7 +564,7 @@ impl Builder<'_> {
         }
 
         let mut rustflags = Rustflags::new(target);
-        if stage != 0 {
+        if build_compiler_stage != 0 {
             if let Ok(s) = env::var("CARGOFLAGS_NOT_BOOTSTRAP") {
                 cargo.args(s.split_whitespace());
             }
@@ -604,7 +606,7 @@ impl Builder<'_> {
         // sysroot. Passing this cfg enables raw-dylib support instead, which makes the native
         // library unnecessary. This can be removed when windows-rs enables raw-dylib
         // unconditionally.
-        if let Mode::Rustc | Mode::ToolRustc | Mode::ToolBootstrap = mode {
+        if let Mode::Rustc | Mode::ToolRustc | Mode::ToolBootstrap | Mode::ToolTarget = mode {
             rustflags.arg("--cfg=windows_raw_dylib");
         }
 
@@ -657,7 +659,7 @@ impl Builder<'_> {
         // FIXME(rust-lang/cargo#5754) we shouldn't be using special command arguments
         // to the host invocation here, but rather Cargo should know what flags to pass rustc
         // itself.
-        if stage == 0 {
+        if build_compiler_stage == 0 {
             hostflags.arg("--cfg=bootstrap");
         }
 
@@ -666,7 +668,7 @@ impl Builder<'_> {
         // #71458.
         let mut rustdocflags = rustflags.clone();
         rustdocflags.propagate_cargo_env("RUSTDOCFLAGS");
-        if stage == 0 {
+        if build_compiler_stage == 0 {
             rustdocflags.env("RUSTDOCFLAGS_BOOTSTRAP");
         } else {
             rustdocflags.env("RUSTDOCFLAGS_NOT_BOOTSTRAP");
@@ -677,7 +679,7 @@ impl Builder<'_> {
         }
 
         match mode {
-            Mode::Std | Mode::ToolBootstrap | Mode::ToolStd => {}
+            Mode::Std | Mode::ToolBootstrap | Mode::ToolStd | Mode::ToolTarget => {}
             Mode::Rustc | Mode::Codegen | Mode::ToolRustc => {
                 // Build proc macros both for the host and the target unless proc-macros are not
                 // supported by the target.
@@ -719,7 +721,7 @@ impl Builder<'_> {
         // feature on the rustc side.
         cargo.arg("-Zbinary-dep-depinfo");
         let allow_features = match mode {
-            Mode::ToolBootstrap | Mode::ToolStd => {
+            Mode::ToolBootstrap | Mode::ToolStd | Mode::ToolTarget => {
                 // Restrict the allowed features so we don't depend on nightly
                 // accidentally.
                 //
@@ -833,7 +835,7 @@ impl Builder<'_> {
         cargo
             .env("RUSTBUILD_NATIVE_DIR", self.native_dir(target))
             .env("RUSTC_REAL", self.rustc(compiler))
-            .env("RUSTC_STAGE", stage.to_string())
+            .env("RUSTC_STAGE", build_compiler_stage.to_string())
             .env("RUSTC_SYSROOT", sysroot)
             .env("RUSTC_LIBDIR", libdir)
             .env("RUSTDOC", self.bootstrap_out.join("rustdoc"))
@@ -878,7 +880,7 @@ impl Builder<'_> {
         let debuginfo_level = match mode {
             Mode::Rustc | Mode::Codegen => self.config.rust_debuginfo_level_rustc,
             Mode::Std => self.config.rust_debuginfo_level_std,
-            Mode::ToolBootstrap | Mode::ToolStd | Mode::ToolRustc => {
+            Mode::ToolBootstrap | Mode::ToolStd | Mode::ToolRustc | Mode::ToolTarget => {
                 self.config.rust_debuginfo_level_tools
             }
         };
@@ -890,11 +892,10 @@ impl Builder<'_> {
             profile_var("DEBUG_ASSERTIONS"),
             match mode {
                 Mode::Std => self.config.std_debug_assertions,
-                Mode::Rustc => self.config.rustc_debug_assertions,
-                Mode::Codegen => self.config.rustc_debug_assertions,
-                Mode::ToolBootstrap => self.config.tools_debug_assertions,
-                Mode::ToolStd => self.config.tools_debug_assertions,
-                Mode::ToolRustc => self.config.tools_debug_assertions,
+                Mode::Rustc | Mode::Codegen => self.config.rustc_debug_assertions,
+                Mode::ToolBootstrap | Mode::ToolStd | Mode::ToolRustc | Mode::ToolTarget => {
+                    self.config.tools_debug_assertions
+                }
             }
             .to_string(),
         );
@@ -965,7 +966,11 @@ impl Builder<'_> {
                     cargo.env("CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR", map_to);
                 }
             }
-            Mode::Std | Mode::ToolBootstrap | Mode::ToolRustc | Mode::ToolStd => {
+            Mode::Std
+            | Mode::ToolBootstrap
+            | Mode::ToolRustc
+            | Mode::ToolStd
+            | Mode::ToolTarget => {
                 if let Some(ref map_to) =
                     self.build.debuginfo_map_to(GitRepo::Rustc, RemapScheme::NonCompiler)
                 {
@@ -1280,7 +1285,7 @@ impl Builder<'_> {
             };
 
             if let Some(limit) = limit
-                && (stage == 0
+                && (build_compiler_stage == 0
                     || self.config.default_codegen_backend(target).unwrap_or_default() == "llvm")
             {
                 rustflags.arg(&format!("-Cllvm-args=-import-instr-limit={limit}"));
diff --git a/src/bootstrap/src/core/builder/mod.rs b/src/bootstrap/src/core/builder/mod.rs
index 7115c5a1cbe..d73e2bce25b 100644
--- a/src/bootstrap/src/core/builder/mod.rs
+++ b/src/bootstrap/src/core/builder/mod.rs
@@ -845,7 +845,6 @@ pub enum Kind {
     #[value(alias = "r")]
     Run,
     Setup,
-    Suggest,
     Vendor,
     Perf,
 }
@@ -869,7 +868,6 @@ impl Kind {
             Kind::Install => "install",
             Kind::Run => "run",
             Kind::Setup => "setup",
-            Kind::Suggest => "suggest",
             Kind::Vendor => "vendor",
             Kind::Perf => "perf",
         }
@@ -881,7 +879,6 @@ impl Kind {
             Kind::Bench => "Benchmarking",
             Kind::Doc => "Documenting",
             Kind::Run => "Running",
-            Kind::Suggest => "Suggesting",
             Kind::Clippy => "Linting",
             Kind::Perf => "Profiling & benchmarking",
             _ => {
@@ -966,6 +963,7 @@ impl<'a> Builder<'a> {
                 tool::RemoteTestServer,
                 tool::RemoteTestClient,
                 tool::RustInstaller,
+                tool::FeaturesStatusDump,
                 tool::Cargo,
                 tool::RustAnalyzer,
                 tool::RustAnalyzerProcMacroSrv,
@@ -987,6 +985,8 @@ impl<'a> Builder<'a> {
                 tool::CoverageDump,
                 tool::LlvmBitcodeLinker,
                 tool::RustcPerf,
+                tool::WasmComponentLd,
+                tool::LldWrapper
             ),
             Kind::Clippy => describe!(
                 clippy::Std,
@@ -1201,7 +1201,7 @@ impl<'a> Builder<'a> {
             Kind::Clean => describe!(clean::CleanAll, clean::Rustc, clean::Std),
             Kind::Vendor => describe!(vendor::Vendor),
             // special-cased in Build::build()
-            Kind::Format | Kind::Suggest | Kind::Perf => vec![],
+            Kind::Format | Kind::Perf => vec![],
             Kind::MiriTest | Kind::MiriSetup => unreachable!(),
         }
     }
@@ -1269,7 +1269,6 @@ impl<'a> Builder<'a> {
             Subcommand::Run { .. } => (Kind::Run, &paths[..]),
             Subcommand::Clean { .. } => (Kind::Clean, &paths[..]),
             Subcommand::Format { .. } => (Kind::Format, &[][..]),
-            Subcommand::Suggest { .. } => (Kind::Suggest, &[][..]),
             Subcommand::Setup { profile: ref path } => (
                 Kind::Setup,
                 path.as_ref().map_or([].as_slice(), |path| std::slice::from_ref(path)),
diff --git a/src/bootstrap/src/core/builder/tests.rs b/src/bootstrap/src/core/builder/tests.rs
index 51a90649692..e60a115b19d 100644
--- a/src/bootstrap/src/core/builder/tests.rs
+++ b/src/bootstrap/src/core/builder/tests.rs
@@ -712,7 +712,11 @@ mod snapshot {
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
         ");
+    }
 
+    #[test]
+    fn build_rustc_no_explicit_stage() {
+        let ctx = TestCtx::new();
         insta::assert_snapshot!(
             ctx.config("build")
                 .path("rustc")
@@ -769,11 +773,11 @@ mod snapshot {
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
         [build] rustc 0 <host> -> LldWrapper 1 <host>
-        [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
+        [build] rustc 0 <host> -> LlvmBitcodeLinker 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
         [build] rustc 1 <host> -> LldWrapper 2 <host>
-        [build] rustc 2 <host> -> LlvmBitcodeLinker 3 <host>
+        [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
         [build] rustc 2 <host> -> std 2 <host>
         [build] rustdoc 1 <host>
         "
@@ -793,17 +797,17 @@ mod snapshot {
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
         [build] rustc 0 <host> -> LldWrapper 1 <host>
-        [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
+        [build] rustc 0 <host> -> LlvmBitcodeLinker 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
         [build] rustc 1 <host> -> LldWrapper 2 <host>
-        [build] rustc 2 <host> -> LlvmBitcodeLinker 3 <host>
+        [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
         [build] rustc 1 <host> -> std 1 <target1>
         [build] rustc 2 <host> -> std 2 <target1>
         [build] llvm <target1>
         [build] rustc 1 <host> -> rustc 2 <target1>
         [build] rustc 1 <host> -> LldWrapper 2 <target1>
-        [build] rustc 2 <target1> -> LlvmBitcodeLinker 3 <target1>
+        [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <target1>
         [build] rustdoc 1 <target1>
         "
         );
@@ -1062,18 +1066,28 @@ mod snapshot {
     fn dist_extended() {
         let ctx = TestCtx::new();
         insta::assert_snapshot!(
-            ctx
-                .config("dist")
-                .args(&["--set", "build.extended=true"])
-                .render_steps(), @r"
+            ctx.config("dist")
+            .args(&[
+                "--set",
+                "build.extended=true",
+                "--set",
+                "rust.llvm-bitcode-linker=true",
+                "--set",
+                "rust.lld=true",
+            ])
+            .render_steps(), @r"
         [build] rustc 0 <host> -> UnstableBookGen 1 <host>
         [build] rustc 0 <host> -> Rustbook 1 <host>
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 0 <host> -> LldWrapper 1 <host>
         [build] rustc 0 <host> -> WasmComponentLd 1 <host>
+        [build] rustc 0 <host> -> LlvmBitcodeLinker 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
+        [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>
         [doc] std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,std,sysroot,test,unwind]
         [build] rustc 2 <host> -> std 2 <host>
@@ -1092,7 +1106,6 @@ mod snapshot {
         [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> -> LlvmBitcodeLinker 2 <host>
         ");
     }
 
@@ -1294,17 +1307,19 @@ mod snapshot {
             ctx.config("check")
                 .path("compiler")
                 .render_steps(), @r"
-        [build] llvm <host>
         [check] rustc 0 <host> -> rustc 1 <host>
         [check] rustc 0 <host> -> cranelift 1 <host>
         [check] rustc 0 <host> -> gcc 1 <host>
         ");
+    }
 
+    #[test]
+    fn check_rustc_no_explicit_stage() {
+        let ctx = TestCtx::new();
         insta::assert_snapshot!(
             ctx.config("check")
                 .path("rustc")
                 .render_steps(), @r"
-        [build] llvm <host>
         [check] rustc 0 <host> -> rustc 1 <host>
         ");
     }
@@ -1324,7 +1339,6 @@ mod snapshot {
                 .path("compiler")
                 .stage(1)
                 .render_steps(), @r"
-        [build] llvm <host>
         [check] rustc 0 <host> -> rustc 1 <host>
         [check] rustc 0 <host> -> cranelift 1 <host>
         [check] rustc 0 <host> -> gcc 1 <host>
@@ -1456,7 +1470,6 @@ mod snapshot {
                 .paths(&["library", "compiler"])
                 .args(&args)
                 .render_steps(), @r"
-        [build] llvm <host>
         [check] rustc 0 <host> -> rustc 1 <host>
         [check] rustc 0 <host> -> cranelift 1 <host>
         [check] rustc 0 <host> -> gcc 1 <host>
@@ -1470,7 +1483,6 @@ mod snapshot {
             ctx.config("check")
                 .path("miri")
                 .render_steps(), @r"
-        [build] llvm <host>
         [check] rustc 0 <host> -> rustc 1 <host>
         [check] rustc 0 <host> -> Miri 1 <host>
         ");
@@ -1491,7 +1503,6 @@ mod snapshot {
                 .path("miri")
                 .stage(1)
                 .render_steps(), @r"
-        [build] llvm <host>
         [check] rustc 0 <host> -> rustc 1 <host>
         [check] rustc 0 <host> -> Miri 1 <host>
         ");
@@ -1544,7 +1555,6 @@ mod snapshot {
             ctx.config("check")
                 .path("rustc_codegen_cranelift")
                 .render_steps(), @r"
-        [build] llvm <host>
         [check] rustc 0 <host> -> rustc 1 <host>
         [check] rustc 0 <host> -> cranelift 1 <host>
         [check] rustc 0 <host> -> gcc 1 <host>
@@ -1558,7 +1568,6 @@ mod snapshot {
             ctx.config("check")
                 .path("rust-analyzer")
                 .render_steps(), @r"
-        [build] llvm <host>
         [check] rustc 0 <host> -> rustc 1 <host>
         [check] rustc 0 <host> -> rust-analyzer 1 <host>
         ");
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index 0039d44785c..22a75183404 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -697,7 +697,7 @@ impl Config {
         config.change_id = toml.change_id.inner;
 
         let Build {
-            mut description,
+            description,
             build,
             host,
             target,
@@ -749,7 +749,7 @@ impl Config {
             compiletest_diff_tool,
             compiletest_use_stage0_libtest,
             tidy_extra_checks,
-            mut ccache,
+            ccache,
             exclude,
         } = toml.build.unwrap_or_default();
 
@@ -942,7 +942,7 @@ impl Config {
         config.rust_profile_use = flags_rust_profile_use;
         config.rust_profile_generate = flags_rust_profile_generate;
 
-        config.apply_rust_config(toml.rust, flags_warnings, &mut description);
+        config.apply_rust_config(toml.rust, flags_warnings);
 
         config.reproducible_artifacts = flags_reproducible_artifact;
         config.description = description;
@@ -963,7 +963,7 @@ impl Config {
             config.channel = channel;
         }
 
-        config.apply_llvm_config(toml.llvm, &mut ccache);
+        config.apply_llvm_config(toml.llvm);
 
         config.apply_gcc_config(toml.gcc);
 
@@ -1050,7 +1050,6 @@ impl Config {
             | Subcommand::Run { .. }
             | Subcommand::Setup { .. }
             | Subcommand::Format { .. }
-            | Subcommand::Suggest { .. }
             | Subcommand::Vendor { .. } => flags_stage.unwrap_or(0),
         };
 
@@ -1098,7 +1097,6 @@ impl Config {
                 | Subcommand::Run { .. }
                 | Subcommand::Setup { .. }
                 | Subcommand::Format { .. }
-                | Subcommand::Suggest { .. }
                 | Subcommand::Vendor { .. }
                 | Subcommand::Perf { .. } => {}
             }
diff --git a/src/bootstrap/src/core/config/flags.rs b/src/bootstrap/src/core/config/flags.rs
index 155b6f58758..1547ca44494 100644
--- a/src/bootstrap/src/core/config/flags.rs
+++ b/src/bootstrap/src/core/config/flags.rs
@@ -481,13 +481,6 @@ Arguments:
         #[arg(value_name = "<PROFILE>|hook|editor|link")]
         profile: Option<PathBuf>,
     },
-    /// Suggest a subset of tests to run, based on modified files
-    #[command(long_about = "\n")]
-    Suggest {
-        /// run suggested tests
-        #[arg(long)]
-        run: bool,
-    },
     /// Vendor dependencies
     Vendor {
         /// Additional `Cargo.toml` to sync and vendor
@@ -518,7 +511,6 @@ impl Subcommand {
             Subcommand::Install => Kind::Install,
             Subcommand::Run { .. } => Kind::Run,
             Subcommand::Setup { .. } => Kind::Setup,
-            Subcommand::Suggest { .. } => Kind::Suggest,
             Subcommand::Vendor { .. } => Kind::Vendor,
             Subcommand::Perf { .. } => Kind::Perf,
         }
diff --git a/src/bootstrap/src/core/config/toml/llvm.rs b/src/bootstrap/src/core/config/toml/llvm.rs
index 4774e202bd8..1f0cecd145c 100644
--- a/src/bootstrap/src/core/config/toml/llvm.rs
+++ b/src/bootstrap/src/core/config/toml/llvm.rs
@@ -17,8 +17,6 @@ define_config! {
         tests: Option<bool> = "tests",
         enzyme: Option<bool> = "enzyme",
         plugins: Option<bool> = "plugins",
-        // FIXME: Remove this field at Q2 2025, it has been replaced by build.ccache
-        ccache: Option<StringOrBool> = "ccache",
         static_libstdcpp: Option<bool> = "static-libstdcpp",
         libzstd: Option<bool> = "libzstd",
         ninja: Option<bool> = "ninja",
@@ -97,7 +95,6 @@ pub fn check_incompatible_options_for_ci_llvm(
         assertions: _,
         tests: _,
         plugins,
-        ccache: _,
         static_libstdcpp: _,
         libzstd,
         ninja: _,
@@ -149,11 +146,7 @@ pub fn check_incompatible_options_for_ci_llvm(
 }
 
 impl Config {
-    pub fn apply_llvm_config(
-        &mut self,
-        toml_llvm: Option<Llvm>,
-        ccache: &mut Option<StringOrBool>,
-    ) {
+    pub fn apply_llvm_config(&mut self, toml_llvm: Option<Llvm>) {
         let mut llvm_tests = None;
         let mut llvm_enzyme = None;
         let mut llvm_offload = None;
@@ -168,7 +161,6 @@ impl Config {
                 tests,
                 enzyme,
                 plugins,
-                ccache: llvm_ccache,
                 static_libstdcpp,
                 libzstd,
                 ninja,
@@ -191,13 +183,7 @@ impl Config {
                 download_ci_llvm,
                 build_config,
             } = llvm;
-            if llvm_ccache.is_some() {
-                eprintln!("Warning: llvm.ccache is deprecated. Use build.ccache instead.");
-            }
 
-            if ccache.is_none() {
-                *ccache = llvm_ccache;
-            }
             set(&mut self.ninja_in_file, ninja);
             llvm_tests = tests;
             llvm_enzyme = enzyme;
diff --git a/src/bootstrap/src/core/config/toml/rust.rs b/src/bootstrap/src/core/config/toml/rust.rs
index 0fae235bb93..71fab0e6ae6 100644
--- a/src/bootstrap/src/core/config/toml/rust.rs
+++ b/src/bootstrap/src/core/config/toml/rust.rs
@@ -36,8 +36,6 @@ define_config! {
         incremental: Option<bool> = "incremental",
         default_linker: Option<String> = "default-linker",
         channel: Option<String> = "channel",
-        // FIXME: Remove this field at Q2 2025, it has been replaced by build.description
-        description: Option<String> = "description",
         musl_root: Option<String> = "musl-root",
         rpath: Option<bool> = "rpath",
         strip: Option<bool> = "strip",
@@ -320,7 +318,6 @@ pub fn check_incompatible_options_for_ci_rustc(
         jemalloc,
         rpath,
         channel,
-        description,
         default_linker,
         std_features,
 
@@ -388,7 +385,6 @@ pub fn check_incompatible_options_for_ci_rustc(
     err!(current_rust_config.std_features, std_features, "rust");
 
     warn!(current_rust_config.channel, channel, "rust");
-    warn!(current_rust_config.description, description, "rust");
 
     Ok(())
 }
@@ -415,12 +411,7 @@ pub(crate) fn validate_codegen_backends(backends: Vec<String>, section: &str) ->
 }
 
 impl Config {
-    pub fn apply_rust_config(
-        &mut self,
-        toml_rust: Option<Rust>,
-        warnings: Warnings,
-        description: &mut Option<String>,
-    ) {
+    pub fn apply_rust_config(&mut self, toml_rust: Option<Rust>, warnings: Warnings) {
         let mut debug = None;
         let mut rustc_debug_assertions = None;
         let mut std_debug_assertions = None;
@@ -459,7 +450,6 @@ impl Config {
                 randomize_layout,
                 default_linker,
                 channel: _, // already handled above
-                description: rust_description,
                 musl_root,
                 rpath,
                 verbose_tests,
@@ -541,6 +531,14 @@ impl Config {
             lld_enabled = lld_enabled_toml;
             std_features = std_features_toml;
 
+            if optimize_toml.as_ref().is_some_and(|v| matches!(v, RustOptimize::Bool(false))) {
+                eprintln!(
+                    "WARNING: setting `optimize` to `false` is known to cause errors and \
+                    should be considered unsupported. Refer to `bootstrap.example.toml` \
+                    for more details."
+                );
+            }
+
             optimize = optimize_toml;
             self.rust_new_symbol_mangling = new_symbol_mangling;
             set(&mut self.rust_optimize_tests, optimize_tests);
@@ -552,14 +550,6 @@ impl Config {
             set(&mut self.jemalloc, jemalloc);
             set(&mut self.test_compare_mode, test_compare_mode);
             set(&mut self.backtrace, backtrace);
-            if rust_description.is_some() {
-                eprintln!(
-                    "Warning: rust.description is deprecated. Use build.description instead."
-                );
-            }
-            if description.is_none() {
-                *description = rust_description;
-            }
             set(&mut self.rust_dist_src, dist_src);
             set(&mut self.verbose_tests, verbose_tests);
             // in the case "false" is set explicitly, do not overwrite the command line args
diff --git a/src/bootstrap/src/core/sanity.rs b/src/bootstrap/src/core/sanity.rs
index f2119e84cce..b39d464493e 100644
--- a/src/bootstrap/src/core/sanity.rs
+++ b/src/bootstrap/src/core/sanity.rs
@@ -216,7 +216,6 @@ than building it.
             build.config.cmd,
             Subcommand::Clean { .. }
                 | Subcommand::Check { .. }
-                | Subcommand::Suggest { .. }
                 | Subcommand::Format { .. }
                 | Subcommand::Setup { .. }
         );
diff --git a/src/bootstrap/src/lib.rs b/src/bootstrap/src/lib.rs
index 66a164703b7..63aab4d116a 100644
--- a/src/bootstrap/src/lib.rs
+++ b/src/bootstrap/src/lib.rs
@@ -253,12 +253,24 @@ pub enum Mode {
     /// These tools are intended to be only executed on the host system that
     /// invokes bootstrap, and they thus cannot be cross-compiled.
     ///
-    /// They are always built using the stage0 compiler, and typically they
+    /// They are always built using the stage0 compiler, and they
     /// can be compiled with stable Rust.
     ///
     /// These tools also essentially do not participate in staging.
     ToolBootstrap,
 
+    /// Build a cross-compilable helper tool. These tools do not depend on unstable features or
+    /// compiler internals, but they might be cross-compilable (so we cannot build them using the
+    /// stage0 compiler, unlike `ToolBootstrap`).
+    ///
+    /// Some of these tools are also shipped in our `dist` archives.
+    /// While we could compile them using the stage0 compiler when not cross-compiling, we instead
+    /// use the in-tree compiler (and std) to build them, so that we can ship e.g. std security
+    /// fixes and avoid depending fully on stage0 for the artifacts that we ship.
+    ///
+    /// This mode is used e.g. for linkers and linker tools invoked by rustc on its host target.
+    ToolTarget,
+
     /// Build a tool which uses the locally built std, placing output in the
     /// "stageN-tools" directory. Its usage is quite rare, mainly used by
     /// compiletest which needs libtest.
@@ -273,11 +285,21 @@ pub enum Mode {
 
 impl Mode {
     pub fn is_tool(&self) -> bool {
-        matches!(self, Mode::ToolBootstrap | Mode::ToolRustc | Mode::ToolStd)
+        match self {
+            Mode::ToolBootstrap | Mode::ToolRustc | Mode::ToolStd | Mode::ToolTarget => true,
+            Mode::Std | Mode::Codegen | Mode::Rustc => false,
+        }
     }
 
     pub fn must_support_dlopen(&self) -> bool {
-        matches!(self, Mode::Std | Mode::Codegen)
+        match self {
+            Mode::Std | Mode::Codegen => true,
+            Mode::ToolBootstrap
+            | Mode::ToolRustc
+            | Mode::ToolStd
+            | Mode::ToolTarget
+            | Mode::Rustc => false,
+        }
     }
 }
 
@@ -651,11 +673,9 @@ impl Build {
         // Handle hard-coded subcommands.
         {
             #[cfg(feature = "tracing")]
-            let _hardcoded_span = span!(
-                tracing::Level::DEBUG,
-                "handling hardcoded subcommands (Format, Suggest, Perf)"
-            )
-            .entered();
+            let _hardcoded_span =
+                span!(tracing::Level::DEBUG, "handling hardcoded subcommands (Format, Perf)")
+                    .entered();
 
             match &self.config.cmd {
                 Subcommand::Format { check, all } => {
@@ -666,9 +686,6 @@ impl Build {
                         &self.config.paths,
                     );
                 }
-                Subcommand::Suggest { run } => {
-                    return core::build_steps::suggest::suggest(&builder::Builder::new(self), *run);
-                }
                 Subcommand::Perf(args) => {
                     return core::build_steps::perf::perf(&builder::Builder::new(self), args);
                 }
@@ -807,17 +824,39 @@ impl Build {
     /// stage when running with a particular host compiler.
     ///
     /// The mode indicates what the root directory is for.
-    fn stage_out(&self, compiler: Compiler, mode: Mode) -> PathBuf {
-        let suffix = match mode {
-            Mode::Std => "-std",
-            Mode::Rustc => "-rustc",
-            Mode::Codegen => "-codegen",
-            Mode::ToolBootstrap => {
-                return self.out.join(compiler.host).join("bootstrap-tools");
+    fn stage_out(&self, build_compiler: Compiler, mode: Mode) -> PathBuf {
+        use std::fmt::Write;
+
+        fn bootstrap_tool() -> (Option<u32>, &'static str) {
+            (None, "bootstrap-tools")
+        }
+        fn staged_tool(build_compiler: Compiler) -> (Option<u32>, &'static str) {
+            (Some(build_compiler.stage), "tools")
+        }
+
+        let (stage, suffix) = match mode {
+            Mode::Std => (Some(build_compiler.stage), "std"),
+            Mode::Rustc => (Some(build_compiler.stage), "rustc"),
+            Mode::Codegen => (Some(build_compiler.stage), "codegen"),
+            Mode::ToolBootstrap => bootstrap_tool(),
+            Mode::ToolStd | Mode::ToolRustc => (Some(build_compiler.stage), "tools"),
+            Mode::ToolTarget => {
+                // If we're not cross-compiling (the common case), share the target directory with
+                // bootstrap tools to reuse the build cache.
+                if build_compiler.stage == 0 {
+                    bootstrap_tool()
+                } else {
+                    staged_tool(build_compiler)
+                }
             }
-            Mode::ToolStd | Mode::ToolRustc => "-tools",
         };
-        self.out.join(compiler.host).join(format!("stage{}{}", compiler.stage, suffix))
+        let path = self.out.join(build_compiler.host);
+        let mut dir_name = String::new();
+        if let Some(stage) = stage {
+            write!(dir_name, "stage{stage}-").unwrap();
+        }
+        dir_name.push_str(suffix);
+        path.join(dir_name)
     }
 
     /// Returns the root output directory for all Cargo output in a given stage,
diff --git a/src/bootstrap/src/utils/cc_detect.rs b/src/bootstrap/src/utils/cc_detect.rs
index dcafeb80f90..d3926df9650 100644
--- a/src/bootstrap/src/utils/cc_detect.rs
+++ b/src/bootstrap/src/utils/cc_detect.rs
@@ -67,7 +67,6 @@ pub fn fill_compilers(build: &mut Build) {
         // We don't need to check cross targets for these commands.
         crate::Subcommand::Clean { .. }
         | crate::Subcommand::Check { .. }
-        | crate::Subcommand::Suggest { .. }
         | crate::Subcommand::Format { .. }
         | crate::Subcommand::Setup { .. } => {
             build.hosts.iter().cloned().chain(iter::once(build.host_target)).collect()
@@ -221,10 +220,15 @@ fn default_compiler(
         }
 
         t if t.contains("-wasi") => {
-            let root = build
-                .wasi_sdk_path
-                .as_ref()
-                .expect("WASI_SDK_PATH mut be configured for a -wasi target");
+            let root = if let Some(path) = build.wasi_sdk_path.as_ref() {
+                path
+            } else {
+                if build.config.is_running_on_ci {
+                    panic!("ERROR: WASI_SDK_PATH must be configured for a -wasi target on CI");
+                }
+                println!("WARNING: WASI_SDK_PATH not set, using default cc/cxx compiler");
+                return None;
+            };
             let compiler = match compiler {
                 Language::C => format!("{t}-clang"),
                 Language::CPlusPlus => format!("{t}-clang++"),
diff --git a/src/bootstrap/src/utils/change_tracker.rs b/src/bootstrap/src/utils/change_tracker.rs
index 1f6ed8129da..f802640a42d 100644
--- a/src/bootstrap/src/utils/change_tracker.rs
+++ b/src/bootstrap/src/utils/change_tracker.rs
@@ -476,4 +476,14 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "Option `tool.TOOL_NAME.features` now works on any subcommand, not just `build`.",
     },
+    ChangeInfo {
+        change_id: 143630,
+        severity: ChangeSeverity::Warning,
+        summary: "The current `./x suggest` implementation has been removed due to it being quite broken and a lack of maintenance bandwidth, with no prejudice against re-implementing it in a more maintainable form.",
+    },
+    ChangeInfo {
+        change_id: 143926,
+        severity: ChangeSeverity::Warning,
+        summary: "Removed `rust.description` and `llvm.ccache` as it was deprecated in #137723 and #136941 long time ago.",
+    },
 ];
diff --git a/src/bootstrap/src/utils/metrics.rs b/src/bootstrap/src/utils/metrics.rs
index 862c4449624..9b1ccc32cb6 100644
--- a/src/bootstrap/src/utils/metrics.rs
+++ b/src/bootstrap/src/utils/metrics.rs
@@ -43,7 +43,7 @@ pub(crate) struct BuildMetrics {
     state: RefCell<MetricsState>,
 }
 
-/// NOTE: this isn't really cloning anything, but `x suggest` doesn't need metrics so this is probably ok.
+// NOTE: this isn't really cloning anything, but necessary for `Build: Clone`.
 impl Clone for BuildMetrics {
     fn clone(&self) -> Self {
         Self::init()
diff --git a/src/build_helper/src/lib.rs b/src/build_helper/src/lib.rs
index 05de8fd2d42..266eedc6245 100644
--- a/src/build_helper/src/lib.rs
+++ b/src/build_helper/src/lib.rs
@@ -5,6 +5,7 @@ pub mod drop_bomb;
 pub mod fs;
 pub mod git;
 pub mod metrics;
+pub mod npm;
 pub mod stage0_parser;
 pub mod targets;
 pub mod util;
diff --git a/src/build_helper/src/npm.rs b/src/build_helper/src/npm.rs
new file mode 100644
index 00000000000..dedef40978d
--- /dev/null
+++ b/src/build_helper/src/npm.rs
@@ -0,0 +1,30 @@
+use std::error::Error;
+use std::path::{Path, PathBuf};
+use std::process::Command;
+use std::{fs, io};
+
+/// Install an exact package version, and return the path of `node_modules`.
+pub fn install_one(
+    out_dir: &Path,
+    npm_bin: &Path,
+    pkg_name: &str,
+    pkg_version: &str,
+) -> Result<PathBuf, io::Error> {
+    let nm_path = out_dir.join("node_modules");
+    let _ = fs::create_dir(&nm_path);
+    let mut child = Command::new(npm_bin)
+        .arg("install")
+        .arg("--audit=false")
+        .arg("--fund=false")
+        .arg(format!("{pkg_name}@{pkg_version}"))
+        .current_dir(out_dir)
+        .spawn()?;
+    let exit_status = child.wait()?;
+    if !exit_status.success() {
+        eprintln!("npm install did not exit successfully");
+        return Err(io::Error::other(Box::<dyn Error + Send + Sync>::from(format!(
+            "npm install returned exit code {exit_status}"
+        ))));
+    }
+    Ok(nm_path)
+}
diff --git a/src/ci/docker/host-aarch64/aarch64-gnu-llvm-19/Dockerfile b/src/ci/docker/host-aarch64/aarch64-gnu-llvm-19/Dockerfile
index 2f9d0010573..e73fbe506f7 100644
--- a/src/ci/docker/host-aarch64/aarch64-gnu-llvm-19/Dockerfile
+++ b/src/ci/docker/host-aarch64/aarch64-gnu-llvm-19/Dockerfile
@@ -50,9 +50,7 @@ ENV RUST_CONFIGURE_ARGS \
 
 COPY scripts/shared.sh /scripts/
 
-ARG SCRIPT_ARG
+COPY scripts/stage_2_test_set1.sh /scripts/
+COPY scripts/stage_2_test_set2.sh /scripts/
 
-COPY scripts/stage_2_test_set1.sh /tmp/
-COPY scripts/stage_2_test_set2.sh /tmp/
-
-ENV SCRIPT "/tmp/${SCRIPT_ARG}"
+ENV SCRIPT "Must specify DOCKER_SCRIPT for this image"
diff --git a/src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile b/src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile
index 44f6a8d2a15..01f19eac1d2 100644
--- a/src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile
@@ -96,12 +96,10 @@ ENV RUST_CONFIGURE_ARGS \
       --set rust.lto=thin \
       --set rust.codegen-units=1
 
-ARG SCRIPT_ARG
-
 COPY host-x86_64/dist-x86_64-linux/dist.sh /scripts/
 COPY host-x86_64/dist-x86_64-linux/dist-alt.sh /scripts/
 
-ENV SCRIPT /scripts/${SCRIPT_ARG}
+ENV SCRIPT "Must specify DOCKER_SCRIPT for this image"
 
 ENV CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER=clang
 
diff --git a/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile b/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
index 58e66fd637a..be3df9d4036 100644
--- a/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
+++ b/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
@@ -23,7 +23,7 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu --disable-optimize-tests
-ARG SCRIPT_ARG
 COPY scripts/stage_2_test_set1.sh /scripts/
 COPY scripts/stage_2_test_set2.sh /scripts/
-ENV SCRIPT ${SCRIPT_ARG}
+COPY scripts/i686-gnu-nopt-2.sh /scripts/
+ENV SCRIPT "Must specify DOCKER_SCRIPT for this image"
diff --git a/src/ci/docker/host-x86_64/i686-gnu/Dockerfile b/src/ci/docker/host-x86_64/i686-gnu/Dockerfile
index a715f7182d2..00cd24b89db 100644
--- a/src/ci/docker/host-x86_64/i686-gnu/Dockerfile
+++ b/src/ci/docker/host-x86_64/i686-gnu/Dockerfile
@@ -24,7 +24,6 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu
-ARG SCRIPT_ARG
 COPY scripts/stage_2_test_set1.sh /scripts/
 COPY scripts/stage_2_test_set2.sh /scripts/
-ENV SCRIPT /scripts/${SCRIPT_ARG}
+ENV SCRIPT "Must specify DOCKER_SCRIPT for this image"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile
index c09be047c6a..5cba7c564f1 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile
@@ -57,12 +57,10 @@ ENV RUST_CONFIGURE_ARGS \
 
 COPY scripts/shared.sh /scripts/
 
-ARG SCRIPT_ARG
+COPY scripts/x86_64-gnu-llvm.sh /scripts/
+COPY scripts/x86_64-gnu-llvm2.sh /scripts/
+COPY scripts/x86_64-gnu-llvm3.sh /scripts/
+COPY scripts/stage_2_test_set1.sh /scripts/
+COPY scripts/stage_2_test_set2.sh /scripts/
 
-COPY scripts/x86_64-gnu-llvm.sh /tmp/
-COPY scripts/x86_64-gnu-llvm2.sh /tmp/
-COPY scripts/x86_64-gnu-llvm3.sh /tmp/
-COPY scripts/stage_2_test_set1.sh /tmp/
-COPY scripts/stage_2_test_set2.sh /tmp/
-
-ENV SCRIPT "/tmp/${SCRIPT_ARG}"
+ENV SCRIPT "Must specify DOCKER_SCRIPT for this image"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile
index 83a3bfb37a5..92c2631000f 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile
@@ -57,12 +57,10 @@ ENV RUST_CONFIGURE_ARGS \
 
 COPY scripts/shared.sh /scripts/
 
-ARG SCRIPT_ARG
+COPY scripts/x86_64-gnu-llvm.sh /scripts/
+COPY scripts/x86_64-gnu-llvm2.sh /scripts/
+COPY scripts/x86_64-gnu-llvm3.sh /scripts/
+COPY scripts/stage_2_test_set1.sh /scripts/
+COPY scripts/stage_2_test_set2.sh /scripts/
 
-COPY scripts/x86_64-gnu-llvm.sh /tmp/
-COPY scripts/x86_64-gnu-llvm2.sh /tmp/
-COPY scripts/x86_64-gnu-llvm3.sh /tmp/
-COPY scripts/stage_2_test_set1.sh /tmp/
-COPY scripts/stage_2_test_set2.sh /tmp/
-
-ENV SCRIPT "/tmp/${SCRIPT_ARG}"
+ENV SCRIPT "Must specify DOCKER_SCRIPT for this image"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-miri/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-miri/Dockerfile
index b937bc3e678..ad2ee85c7bb 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-miri/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-miri/Dockerfile
@@ -46,12 +46,4 @@ ENV HOST_TARGET x86_64-unknown-linux-gnu
 
 COPY scripts/shared.sh /scripts/
 
-# For now, we need to use `--unsafe-perm=true` to go around an issue when npm tries
-# to create a new folder. For reference:
-# https://github.com/puppeteer/puppeteer/issues/375
-#
-# We also specify the version in case we need to update it to go around cache limitations.
-#
-# The `browser-ui-test.version` file is also used by bootstrap to emit warnings in case
-# the local version of the package is different than the one used by the CI.
 ENV SCRIPT /tmp/check-miri.sh ../x.py
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
index e770c58bd9c..95357d22937 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
@@ -76,8 +76,6 @@ COPY scripts/nodejs.sh /scripts/
 RUN sh /scripts/nodejs.sh /node
 ENV PATH="/node/bin:${PATH}"
 
-COPY host-x86_64/x86_64-gnu-tools/browser-ui-test.version /tmp/
-
 ENV RUST_CONFIGURE_ARGS \
   --build=x86_64-unknown-linux-gnu \
   --save-toolstates=/tmp/toolstate/toolstates.json \
@@ -91,15 +89,6 @@ ENV HOST_TARGET x86_64-unknown-linux-gnu
 
 COPY scripts/shared.sh /scripts/
 
-# For now, we need to use `--unsafe-perm=true` to go around an issue when npm tries
-# to create a new folder. For reference:
-# https://github.com/puppeteer/puppeteer/issues/375
-#
-# We also specify the version in case we need to update it to go around cache limitations.
-#
-# The `browser-ui-test.version` file is also used by bootstrap to emit warnings in case
-# the local version of the package is different than the one used by the CI.
 ENV SCRIPT /tmp/checktools.sh ../x.py && \
-  npm install browser-ui-test@$(head -n 1 /tmp/browser-ui-test.version) --unsafe-perm=true && \
   python3 ../x.py check compiletest --set build.compiletest-use-stage0-libtest=true && \
   python3 ../x.py test tests/rustdoc-gui --stage 2 --test-args "'--jobs 1'"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-tools/browser-ui-test.version b/src/ci/docker/host-x86_64/x86_64-gnu-tools/browser-ui-test.version
deleted file mode 100644
index b9f8e558df4..00000000000
--- a/src/ci/docker/host-x86_64/x86_64-gnu-tools/browser-ui-test.version
+++ /dev/null
@@ -1 +0,0 @@
-0.21.1
\ No newline at end of file
diff --git a/src/ci/docker/run.sh b/src/ci/docker/run.sh
index da7d084d48d..044f5a8fff3 100755
--- a/src/ci/docker/run.sh
+++ b/src/ci/docker/run.sh
@@ -114,14 +114,6 @@ if [ -f "$docker_dir/$image/Dockerfile" ]; then
         "$context"
     )
 
-    # If the environment variable DOCKER_SCRIPT is defined,
-    # set the build argument SCRIPT_ARG to DOCKER_SCRIPT.
-    # In this way, we run the script defined in CI,
-    # instead of the one defined in the Dockerfile.
-    if [ -n "${DOCKER_SCRIPT+x}" ]; then
-      build_args+=("--build-arg" "SCRIPT_ARG=${DOCKER_SCRIPT}")
-    fi
-
     GHCR_BUILDKIT_IMAGE="ghcr.io/rust-lang/buildkit:buildx-stable-1"
     # On non-CI jobs, we try to download a pre-built image from the rust-lang-ci
     # ghcr.io registry. If it is not possible, we fall back to building the image
@@ -341,6 +333,10 @@ if [ "$ENABLE_GCC_CODEGEN" = "1" ]; then
   echo "Setting extra environment values for docker: $extra_env"
 fi
 
+if [ -n "${DOCKER_SCRIPT}" ]; then
+  extra_env="$extra_env --env SCRIPT=\"/scripts/${DOCKER_SCRIPT}\""
+fi
+
 docker \
   run \
   --workdir /checkout/obj \
diff --git a/src/ci/docker/scripts/i686-gnu-nopt-2.sh b/src/ci/docker/scripts/i686-gnu-nopt-2.sh
new file mode 100755
index 00000000000..4c171739daf
--- /dev/null
+++ b/src/ci/docker/scripts/i686-gnu-nopt-2.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+set -ex
+
+python3 ../x.py test --stage 1 --set rust.optimize=false library/std &&
+/scripts/stage_2_test_set2.sh
diff --git a/src/ci/docker/scripts/x86_64-gnu-llvm2.sh b/src/ci/docker/scripts/x86_64-gnu-llvm2.sh
index fe5382aaa48..0060b9bfd23 100755
--- a/src/ci/docker/scripts/x86_64-gnu-llvm2.sh
+++ b/src/ci/docker/scripts/x86_64-gnu-llvm2.sh
@@ -4,7 +4,7 @@ set -ex
 
 ##### Test stage 2 #####
 
-/tmp/stage_2_test_set1.sh
+/scripts/stage_2_test_set1.sh
 
 # Run the `mir-opt` tests again but this time for a 32-bit target.
 # This enforces that tests using `// EMIT_MIR_FOR_EACH_BIT_WIDTH` have
diff --git a/src/ci/github-actions/jobs.yml b/src/ci/github-actions/jobs.yml
index 445fc0dd018..0a6ebe44b3d 100644
--- a/src/ci/github-actions/jobs.yml
+++ b/src/ci/github-actions/jobs.yml
@@ -34,6 +34,8 @@ runners:
     os: windows-2022
     <<: *base-job
 
+  # NOTE: windows-2025 has less disk space available than windows-2022,
+  # because the D drive is missing.
   - &job-windows-25
     os: windows-2025
     <<: *base-job
@@ -170,9 +172,9 @@ try:
 optional:
   # This job is used just to test optional jobs.
   # It will be replaced by tier 2 and tier 3 jobs in the future.
-  - name: optional-mingw-check-1
+  - name: optional-pr-check-1
     env:
-      IMAGE: mingw-check-1
+      IMAGE: pr-check-1
     <<: *job-linux-4c
 
 # Main CI jobs that have to be green to merge a commit into master
@@ -315,16 +317,14 @@ auto:
   - name: i686-gnu-nopt-1
     env:
       IMAGE: i686-gnu-nopt
-      DOCKER_SCRIPT: /scripts/stage_2_test_set1.sh
+      DOCKER_SCRIPT: stage_2_test_set1.sh
     <<: *job-linux-4c
 
   # Skip tests that run in i686-gnu-nopt-1
   - name: i686-gnu-nopt-2
     env:
       IMAGE: i686-gnu-nopt
-      DOCKER_SCRIPT: >-
-        python3 ../x.py test --stage 1 --set rust.optimize=false library/std &&
-        /scripts/stage_2_test_set2.sh
+      DOCKER_SCRIPT: i686-gnu-nopt-2.sh
     <<: *job-linux-4c
 
   - name: pr-check-1
@@ -544,13 +544,13 @@ auto:
     env:
       RUST_CONFIGURE_ARGS: --build=x86_64-pc-windows-msvc --enable-sanitizers --enable-profiler
       SCRIPT: make ci-msvc-py
-    <<: *job-windows-25
+    <<: *job-windows
 
   - name: x86_64-msvc-2
     env:
       RUST_CONFIGURE_ARGS: --build=x86_64-pc-windows-msvc --enable-sanitizers --enable-profiler
       SCRIPT: make ci-msvc-ps1
-    <<: *job-windows-25
+    <<: *job-windows
 
   # i686-msvc is split into two jobs to run tests in parallel.
   - name: i686-msvc-1
diff --git a/src/ci/scripts/install-mingw.sh b/src/ci/scripts/install-mingw.sh
index ad852071f29..ed87628659b 100755
--- a/src/ci/scripts/install-mingw.sh
+++ b/src/ci/scripts/install-mingw.sh
@@ -43,4 +43,9 @@ if isWindows && isKnownToBeMingwBuild; then
     curl -o mingw.7z "${MIRRORS_BASE}/${mingw_archive}"
     7z x -y mingw.7z > /dev/null
     ciCommandAddPath "$(cygpath -m "$(pwd)/${mingw_dir}/bin")"
+
+    # Initialize mingw for the user.
+    # This should be done by github but isn't for some reason.
+    # (see https://github.com/actions/runner-images/issues/12600)
+    /c/msys64/usr/bin/bash -lc ' '
 fi
diff --git a/src/doc/book b/src/doc/book
-Subproject ef1ce8f87a8b18feb1b6a9cf9a4939a79bde679
+Subproject b2d1a0821e12a676b496d61891b8e3d374a8e83
diff --git a/src/doc/embedded-book b/src/doc/embedded-book
-Subproject 41f688a598a5022b749e23d37f3c524f6a0b28e
+Subproject fe88fbb68391a465680dd91109f0a151a1676f3
diff --git a/src/doc/nomicon b/src/doc/nomicon
-Subproject 8b61acfaea822e9ac926190bc8f15791c33336e
+Subproject 3ff384320598bbe8d8cfe5cb8f18f78a3a3e6b1
diff --git a/src/doc/reference b/src/doc/reference
-Subproject e9fc99f107840813916f62e16b3f6d9556e1f2d
+Subproject 1f45bd41fa6c17b7c048ed6bfe5f168c4311206
diff --git a/src/doc/rust-by-example b/src/doc/rust-by-example
-Subproject 288b4e4948add43f387cad35adc7b1c54ca6fe1
+Subproject e386be5f44af711854207c11fdd61bb576270b0
diff --git a/src/doc/rustc-dev-guide/.github/workflows/rustc-pull.yml b/src/doc/rustc-dev-guide/.github/workflows/rustc-pull.yml
index 1e430d8b4e6..ad570ee4595 100644
--- a/src/doc/rustc-dev-guide/.github/workflows/rustc-pull.yml
+++ b/src/doc/rustc-dev-guide/.github/workflows/rustc-pull.yml
@@ -9,106 +9,12 @@ on:
 jobs:
   pull:
     if: github.repository == 'rust-lang/rustc-dev-guide'
-    runs-on: ubuntu-latest
-    outputs:
-      pr_url: ${{ steps.update-pr.outputs.pr_url }}
-    permissions:
-      contents: write
-      pull-requests: write
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          # We need the full history for josh to work
-          fetch-depth: '0'
-      - name: Install stable Rust toolchain
-        run: rustup update stable
-      - uses: Swatinem/rust-cache@v2
-        with:
-          workspaces: "josh-sync"
-          # Cache the josh directory with checked out rustc
-          cache-directories: "/home/runner/.cache/rustc-dev-guide-josh"
-      - name: Install josh
-        run: RUSTFLAGS="--cap-lints warn" cargo install josh-proxy --git https://github.com/josh-project/josh --tag r24.10.04
-      - name: Setup bot git name and email
-        run: |
-          git config --global user.name 'The rustc-dev-guide Cronjob Bot'
-          git config --global user.email 'github-actions@github.com'
-      - name: Perform rustc-pull
-        id: rustc-pull
-        # Turn off -e to disable early exit
-        shell: bash {0}
-        run: |
-          cargo run --manifest-path josh-sync/Cargo.toml -- rustc-pull
-          exitcode=$?
-
-          # If no pull was performed, we want to mark this job as successful,
-          # but we do not want to perform the follow-up steps.
-          if [ $exitcode -eq 0 ]; then
-            echo "pull_result=pull-finished" >> $GITHUB_OUTPUT
-          elif [ $exitcode -eq 2 ]; then
-            echo "pull_result=skipped" >> $GITHUB_OUTPUT
-            exitcode=0
-          fi
-
-          exit ${exitcode}
-      - name: Push changes to a branch
-        if: ${{ steps.rustc-pull.outputs.pull_result == 'pull-finished' }}
-        run: |
-          # Update a sticky branch that is used only for rustc pulls
-          BRANCH="rustc-pull"
-          git switch -c $BRANCH
-          git push -u origin $BRANCH --force
-      - name: Create pull request
-        id: update-pr
-        if: ${{ steps.rustc-pull.outputs.pull_result == 'pull-finished' }}
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        run: |
-          # Check if an open pull request for an rustc pull update already exists
-          # If it does, the previous push has just updated it
-          # If not, we create it now
-          RESULT=`gh pr list --author github-actions[bot] --state open -q 'map(select(.title=="Rustc pull update")) | length' --json title`
-          if [[ "$RESULT" -eq 0 ]]; then
-            echo "Creating new pull request"
-            PR_URL=`gh pr create -B master --title 'Rustc pull update' --body 'Latest update from rustc.'`
-            echo "pr_url=$PR_URL" >> $GITHUB_OUTPUT
-          else
-            PR_URL=`gh pr list --author github-actions[bot] --state open -q 'map(select(.title=="Rustc pull update")) | .[0].url' --json url,title`
-            echo "Updating pull request ${PR_URL}"
-            echo "pr_url=$PR_URL" >> $GITHUB_OUTPUT
-          fi
-  send-zulip-message:
-    needs: [pull]
-    if: ${{ !cancelled() }}
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - name: Compute message
-        id: create-message
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        run: |
-          if [ "${{ needs.pull.result }}" == "failure" ]; then
-            WORKFLOW_URL="${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
-            echo "message=Rustc pull sync failed. Check out the [workflow URL]($WORKFLOW_URL)." >> $GITHUB_OUTPUT
-          else
-            CREATED_AT=`gh pr list --author github-actions[bot] --state open -q 'map(select(.title=="Rustc pull update")) | .[0].createdAt' --json createdAt,title`
-            PR_URL=`gh pr list --author github-actions[bot] --state open -q 'map(select(.title=="Rustc pull update")) | .[0].url' --json url,title`
-            week_ago=$(date +%F -d '7 days ago')
-
-            # If there is an open PR that is at least a week old, post a message about it
-            if [[ -n $DATE_GH && $DATE_GH < $week_ago ]]; then
-              echo "message=A PR with a Rustc pull has been opened for more a week. Check out the [PR](${PR_URL})." >> $GITHUB_OUTPUT
-            fi
-          fi
-      - name: Send a Zulip message about updated PR
-        if: ${{ steps.create-message.outputs.message != '' }}
-        uses: zulip/github-actions-zulip/send-message@e4c8f27c732ba9bd98ac6be0583096dea82feea5
-        with:
-          api-key: ${{ secrets.ZULIP_API_TOKEN }}
-          email: "rustc-dev-guide-gha-notif-bot@rust-lang.zulipchat.com"
-          organization-url: "https://rust-lang.zulipchat.com"
-          to: 196385
-          type: "stream"
-          topic: "Subtree sync automation"
-          content: ${{ steps.create-message.outputs.message }}
+    uses: rust-lang/josh-sync/.github/workflows/rustc-pull.yml@main
+    with:
+      zulip-stream-id: 196385
+      zulip-bot-email:  "rustc-dev-guide-gha-notif-bot@rust-lang.zulipchat.com"
+      pr-base-branch: master
+      branch-name: rustc-pull
+    secrets:
+      zulip-api-token: ${{ secrets.ZULIP_API_TOKEN }}
+      token: ${{ secrets.GITHUB_TOKEN }}
diff --git a/src/doc/rustc-dev-guide/README.md b/src/doc/rustc-dev-guide/README.md
index 0425c15f83c..5932da467ab 100644
--- a/src/doc/rustc-dev-guide/README.md
+++ b/src/doc/rustc-dev-guide/README.md
@@ -72,49 +72,6 @@ including the `<!-- toc -->` marker at the place where you want the TOC.
 
 ## Synchronizing josh subtree with rustc
 
-This repository is linked to `rust-lang/rust` as a [josh](https://josh-project.github.io/josh/intro.html) subtree. You can use the following commands to synchronize the subtree in both directions.
+This repository is linked to `rust-lang/rust` as a [josh](https://josh-project.github.io/josh/intro.html) subtree. You can use the [rustc-josh-sync](https://github.com/rust-lang/josh-sync) tool to perform synchronization.
 
-You'll need to install `josh-proxy` locally via
-
-```
-cargo install josh-proxy --git https://github.com/josh-project/josh --tag r24.10.04
-```
-Older versions of `josh-proxy` may not round trip commits losslessly so it is important to install this exact version.
-
-### Pull changes from `rust-lang/rust` into this repository
-
-1) Checkout a new branch that will be used to create a PR into `rust-lang/rustc-dev-guide`
-2) Run the pull command
-    ```
-    cargo run --manifest-path josh-sync/Cargo.toml rustc-pull
-    ```
-3) Push the branch to your fork and create a PR into `rustc-dev-guide`
-
-### Push changes from this repository into `rust-lang/rust`
-
-NOTE: If you use Git protocol to push to your fork of `rust-lang/rust`,
-ensure that you have this entry in your Git config,
-else the 2 steps that follow would prompt for a username and password:
-
-```
-[url "git@github.com:"]
-insteadOf = "https://github.com/"
-```
-
-1) Run the push command to create a branch named `<branch-name>` in a `rustc` fork under the `<gh-username>` account
-    ```
-    cargo run --manifest-path josh-sync/Cargo.toml rustc-push <branch-name> <gh-username>
-    ```
-2) Create a PR from `<branch-name>` into `rust-lang/rust`
-
-#### Minimal git config
-
-For simplicity (ease of implementation purposes), the josh-sync script simply calls out to system git. This means that the git invocation may be influenced by global (or local) git configuration.
-
-You may observe "Nothing to pull" even if you *know* rustc-pull has something to pull if your global git config sets `fetch.prunetags = true` (and possibly other configurations may cause unexpected outcomes).
-
-To minimize the likelihood of this happening, you may wish to keep a separate *minimal* git config that *only* has `[user]` entries from global git config, then repoint system git to use the minimal git config instead. E.g.
-
-```
-GIT_CONFIG_GLOBAL=/path/to/minimal/gitconfig GIT_CONFIG_SYSTEM='' cargo run --manifest-path josh-sync/Cargo.toml -- rustc-pull
-```
+You can find a guide on how to perform the synchronization [here](./src/external-repos.md#synchronizing-a-josh-subtree).
diff --git a/src/doc/rustc-dev-guide/josh-sync/Cargo.lock b/src/doc/rustc-dev-guide/josh-sync/Cargo.lock
deleted file mode 100644
index a8183a740db..00000000000
--- a/src/doc/rustc-dev-guide/josh-sync/Cargo.lock
+++ /dev/null
@@ -1,430 +0,0 @@
-# This file is automatically @generated by Cargo.
-# It is not intended for manual editing.
-version = 4
-
-[[package]]
-name = "anstream"
-version = "0.6.18"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8acc5369981196006228e28809f761875c0327210a891e941f4c683b3a99529b"
-dependencies = [
- "anstyle",
- "anstyle-parse",
- "anstyle-query",
- "anstyle-wincon",
- "colorchoice",
- "is_terminal_polyfill",
- "utf8parse",
-]
-
-[[package]]
-name = "anstyle"
-version = "1.0.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "55cc3b69f167a1ef2e161439aa98aed94e6028e5f9a59be9a6ffb47aef1651f9"
-
-[[package]]
-name = "anstyle-parse"
-version = "0.2.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b2d16507662817a6a20a9ea92df6652ee4f94f914589377d69f3b21bc5798a9"
-dependencies = [
- "utf8parse",
-]
-
-[[package]]
-name = "anstyle-query"
-version = "1.1.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "79947af37f4177cfead1110013d678905c37501914fba0efea834c3fe9a8d60c"
-dependencies = [
- "windows-sys 0.59.0",
-]
-
-[[package]]
-name = "anstyle-wincon"
-version = "3.0.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2109dbce0e72be3ec00bed26e6a7479ca384ad226efdd66db8fa2e3a38c83125"
-dependencies = [
- "anstyle",
- "windows-sys 0.59.0",
-]
-
-[[package]]
-name = "anyhow"
-version = "1.0.95"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34ac096ce696dc2fcabef30516bb13c0a68a11d30131d3df6f04711467681b04"
-
-[[package]]
-name = "bitflags"
-version = "2.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
-
-[[package]]
-name = "cfg-if"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
-
-[[package]]
-name = "clap"
-version = "4.5.23"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3135e7ec2ef7b10c6ed8950f0f792ed96ee093fa088608f1c76e569722700c84"
-dependencies = [
- "clap_builder",
- "clap_derive",
-]
-
-[[package]]
-name = "clap_builder"
-version = "4.5.23"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "30582fc632330df2bd26877bde0c1f4470d57c582bbc070376afcd04d8cb4838"
-dependencies = [
- "anstream",
- "anstyle",
- "clap_lex",
- "strsim",
-]
-
-[[package]]
-name = "clap_derive"
-version = "4.5.18"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4ac6a0c7b1a9e9a5186361f67dfa1b88213572f427fb9ab038efb2bd8c582dab"
-dependencies = [
- "heck",
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "clap_lex"
-version = "0.7.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f46ad14479a25103f283c0f10005961cf086d8dc42205bb44c46ac563475dca6"
-
-[[package]]
-name = "colorchoice"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b63caa9aa9397e2d9480a9b13673856c78d8ac123288526c37d7839f2a86990"
-
-[[package]]
-name = "directories"
-version = "5.0.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a49173b84e034382284f27f1af4dcbbd231ffa358c0fe316541a7337f376a35"
-dependencies = [
- "dirs-sys",
-]
-
-[[package]]
-name = "dirs-sys"
-version = "0.4.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "520f05a5cbd335fae5a99ff7a6ab8627577660ee5cfd6a94a6a929b52ff0321c"
-dependencies = [
- "libc",
- "option-ext",
- "redox_users",
- "windows-sys 0.48.0",
-]
-
-[[package]]
-name = "getrandom"
-version = "0.2.15"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
-dependencies = [
- "cfg-if",
- "libc",
- "wasi",
-]
-
-[[package]]
-name = "heck"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
-
-[[package]]
-name = "is_terminal_polyfill"
-version = "1.70.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
-
-[[package]]
-name = "josh-sync"
-version = "0.0.0"
-dependencies = [
- "anyhow",
- "clap",
- "directories",
- "xshell",
-]
-
-[[package]]
-name = "libc"
-version = "0.2.169"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b5aba8db14291edd000dfcc4d620c7ebfb122c613afb886ca8803fa4e128a20a"
-
-[[package]]
-name = "libredox"
-version = "0.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c0ff37bd590ca25063e35af745c343cb7a0271906fb7b37e4813e8f79f00268d"
-dependencies = [
- "bitflags",
- "libc",
-]
-
-[[package]]
-name = "option-ext"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "04744f49eae99ab78e0d5c0b603ab218f515ea8cfe5a456d7629ad883a3b6e7d"
-
-[[package]]
-name = "proc-macro2"
-version = "1.0.92"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "37d3544b3f2748c54e147655edb5025752e2303145b5aefb3c3ea2c78b973bb0"
-dependencies = [
- "unicode-ident",
-]
-
-[[package]]
-name = "quote"
-version = "1.0.38"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0e4dccaaaf89514f546c693ddc140f729f958c247918a13380cccc6078391acc"
-dependencies = [
- "proc-macro2",
-]
-
-[[package]]
-name = "redox_users"
-version = "0.4.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba009ff324d1fc1b900bd1fdb31564febe58a8ccc8a6fdbb93b543d33b13ca43"
-dependencies = [
- "getrandom",
- "libredox",
- "thiserror",
-]
-
-[[package]]
-name = "strsim"
-version = "0.11.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
-
-[[package]]
-name = "syn"
-version = "2.0.93"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c786062daee0d6db1132800e623df74274a0a87322d8e183338e01b3d98d058"
-dependencies = [
- "proc-macro2",
- "quote",
- "unicode-ident",
-]
-
-[[package]]
-name = "thiserror"
-version = "1.0.69"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b6aaf5339b578ea85b50e080feb250a3e8ae8cfcdff9a461c9ec2904bc923f52"
-dependencies = [
- "thiserror-impl",
-]
-
-[[package]]
-name = "thiserror-impl"
-version = "1.0.69"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4fee6c4efc90059e10f81e6d42c60a18f76588c3d74cb83a0b242a2b6c7504c1"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "unicode-ident"
-version = "1.0.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "adb9e6ca4f869e1180728b7950e35922a7fc6397f7b641499e8f3ef06e50dc83"
-
-[[package]]
-name = "utf8parse"
-version = "0.2.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
-
-[[package]]
-name = "wasi"
-version = "0.11.0+wasi-snapshot-preview1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
-
-[[package]]
-name = "windows-sys"
-version = "0.48.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "677d2418bec65e3338edb076e806bc1ec15693c5d0104683f2efe857f61056a9"
-dependencies = [
- "windows-targets 0.48.5",
-]
-
-[[package]]
-name = "windows-sys"
-version = "0.59.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
-dependencies = [
- "windows-targets 0.52.6",
-]
-
-[[package]]
-name = "windows-targets"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a2fa6e2155d7247be68c096456083145c183cbbbc2764150dda45a87197940c"
-dependencies = [
- "windows_aarch64_gnullvm 0.48.5",
- "windows_aarch64_msvc 0.48.5",
- "windows_i686_gnu 0.48.5",
- "windows_i686_msvc 0.48.5",
- "windows_x86_64_gnu 0.48.5",
- "windows_x86_64_gnullvm 0.48.5",
- "windows_x86_64_msvc 0.48.5",
-]
-
-[[package]]
-name = "windows-targets"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
-dependencies = [
- "windows_aarch64_gnullvm 0.52.6",
- "windows_aarch64_msvc 0.52.6",
- "windows_i686_gnu 0.52.6",
- "windows_i686_gnullvm",
- "windows_i686_msvc 0.52.6",
- "windows_x86_64_gnu 0.52.6",
- "windows_x86_64_gnullvm 0.52.6",
- "windows_x86_64_msvc 0.52.6",
-]
-
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
-
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
-
-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
-
-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
-
-[[package]]
-name = "windows_i686_gnu"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
-
-[[package]]
-name = "windows_i686_gnu"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
-
-[[package]]
-name = "windows_i686_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
-
-[[package]]
-name = "windows_i686_msvc"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
-
-[[package]]
-name = "windows_i686_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
-
-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
-
-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
-
-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
-
-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
-
-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
-
-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
-
-[[package]]
-name = "xshell"
-version = "0.2.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e7290c623014758632efe00737145b6867b66292c42167f2ec381eb566a373d"
-dependencies = [
- "xshell-macros",
-]
-
-[[package]]
-name = "xshell-macros"
-version = "0.2.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32ac00cd3f8ec9c1d33fb3e7958a82df6989c42d747bd326c822b1d625283547"
diff --git a/src/doc/rustc-dev-guide/josh-sync/Cargo.toml b/src/doc/rustc-dev-guide/josh-sync/Cargo.toml
deleted file mode 100644
index 1f8bf2a0093..00000000000
--- a/src/doc/rustc-dev-guide/josh-sync/Cargo.toml
+++ /dev/null
@@ -1,9 +0,0 @@
-[package]
-name = "josh-sync"
-edition = "2024"
-
-[dependencies]
-anyhow = "1.0.95"
-clap = { version = "4.5.21", features = ["derive"] }
-directories = "5"
-xshell = "0.2.6"
diff --git a/src/doc/rustc-dev-guide/josh-sync/README.md b/src/doc/rustc-dev-guide/josh-sync/README.md
deleted file mode 100644
index a3dd876e8b8..00000000000
--- a/src/doc/rustc-dev-guide/josh-sync/README.md
+++ /dev/null
@@ -1,4 +0,0 @@
-# Git josh sync
-This utility serves for syncing the josh git subtree to and from the rust-lang/rust repository.
-
-See CLI help for usage.
diff --git a/src/doc/rustc-dev-guide/josh-sync/src/main.rs b/src/doc/rustc-dev-guide/josh-sync/src/main.rs
deleted file mode 100644
index aeedee5be22..00000000000
--- a/src/doc/rustc-dev-guide/josh-sync/src/main.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-use clap::Parser;
-
-use crate::sync::{GitSync, RustcPullError};
-
-mod sync;
-
-#[derive(clap::Parser)]
-enum Args {
-    /// Pull changes from the main `rustc` repository.
-    /// This creates new commits that should be then merged into `rustc-dev-guide`.
-    RustcPull,
-    /// Push changes from `rustc-dev-guide` to the given `branch` of a `rustc` fork under the given
-    /// GitHub `username`.
-    /// The pushed branch should then be merged into the `rustc` repository.
-    RustcPush { branch: String, github_username: String },
-}
-
-fn main() -> anyhow::Result<()> {
-    let args = Args::parse();
-    let sync = GitSync::from_current_dir()?;
-    match args {
-        Args::RustcPull => {
-            if let Err(error) = sync.rustc_pull(None) {
-                match error {
-                    RustcPullError::NothingToPull => {
-                        eprintln!("Nothing to pull");
-                        std::process::exit(2);
-                    }
-                    RustcPullError::PullFailed(error) => {
-                        eprintln!("Pull failure: {error:?}");
-                        std::process::exit(1);
-                    }
-                }
-            }
-        }
-        Args::RustcPush { github_username, branch } => {
-            sync.rustc_push(github_username, branch)?;
-        }
-    }
-    Ok(())
-}
diff --git a/src/doc/rustc-dev-guide/josh-sync/src/sync.rs b/src/doc/rustc-dev-guide/josh-sync/src/sync.rs
deleted file mode 100644
index ed38d1403a0..00000000000
--- a/src/doc/rustc-dev-guide/josh-sync/src/sync.rs
+++ /dev/null
@@ -1,275 +0,0 @@
-use std::io::Write;
-use std::ops::Not;
-use std::path::PathBuf;
-use std::time::Duration;
-use std::{env, net, process};
-
-use anyhow::{Context, anyhow, bail};
-use xshell::{Shell, cmd};
-
-/// Used for rustc syncs.
-const JOSH_FILTER: &str = ":/src/doc/rustc-dev-guide";
-const JOSH_PORT: u16 = 42042;
-const UPSTREAM_REPO: &str = "rust-lang/rust";
-
-pub enum RustcPullError {
-    /// No changes are available to be pulled.
-    NothingToPull,
-    /// A rustc-pull has failed, probably a git operation error has occurred.
-    PullFailed(anyhow::Error),
-}
-
-impl<E> From<E> for RustcPullError
-where
-    E: Into<anyhow::Error>,
-{
-    fn from(error: E) -> Self {
-        Self::PullFailed(error.into())
-    }
-}
-
-pub struct GitSync {
-    dir: PathBuf,
-}
-
-/// This code was adapted from the miri repository
-/// (https://github.com/rust-lang/miri/blob/6a68a79f38064c3bc30617cca4bdbfb2c336b140/miri-script/src/commands.rs#L236).
-impl GitSync {
-    pub fn from_current_dir() -> anyhow::Result<Self> {
-        Ok(Self { dir: std::env::current_dir()? })
-    }
-
-    pub fn rustc_pull(&self, commit: Option<String>) -> Result<(), RustcPullError> {
-        let sh = Shell::new()?;
-        sh.change_dir(&self.dir);
-        let commit = commit.map(Ok).unwrap_or_else(|| {
-            let rust_repo_head =
-                cmd!(sh, "git ls-remote https://github.com/{UPSTREAM_REPO}/ HEAD").read()?;
-            rust_repo_head
-                .split_whitespace()
-                .next()
-                .map(|front| front.trim().to_owned())
-                .ok_or_else(|| anyhow!("Could not obtain Rust repo HEAD from remote."))
-        })?;
-        // Make sure the repo is clean.
-        if cmd!(sh, "git status --untracked-files=no --porcelain").read()?.is_empty().not() {
-            return Err(anyhow::anyhow!(
-                "working directory must be clean before performing rustc pull"
-            )
-            .into());
-        }
-        // Make sure josh is running.
-        let josh = Self::start_josh()?;
-        let josh_url =
-            format!("http://localhost:{JOSH_PORT}/{UPSTREAM_REPO}.git@{commit}{JOSH_FILTER}.git");
-
-        let previous_base_commit = sh.read_file("rust-version")?.trim().to_string();
-        if previous_base_commit == commit {
-            return Err(RustcPullError::NothingToPull);
-        }
-
-        // Update rust-version file. As a separate commit, since making it part of
-        // the merge has confused the heck out of josh in the past.
-        // We pass `--no-verify` to avoid running git hooks.
-        // We do this before the merge so that if there are merge conflicts, we have
-        // the right rust-version file while resolving them.
-        sh.write_file("rust-version", format!("{commit}\n"))?;
-        const PREPARING_COMMIT_MESSAGE: &str = "Preparing for merge from rustc";
-        cmd!(sh, "git commit rust-version --no-verify -m {PREPARING_COMMIT_MESSAGE}")
-            .run()
-            .context("FAILED to commit rust-version file, something went wrong")?;
-
-        // Fetch given rustc commit.
-        cmd!(sh, "git fetch {josh_url}")
-            .run()
-            .inspect_err(|_| {
-                // Try to un-do the previous `git commit`, to leave the repo in the state we found it.
-                cmd!(sh, "git reset --hard HEAD^")
-                    .run()
-                    .expect("FAILED to clean up again after failed `git fetch`, sorry for that");
-            })
-            .context("FAILED to fetch new commits, something went wrong (committing the rust-version file has been undone)")?;
-
-        // This should not add any new root commits. So count those before and after merging.
-        let num_roots = || -> anyhow::Result<u32> {
-            Ok(cmd!(sh, "git rev-list HEAD --max-parents=0 --count")
-                .read()
-                .context("failed to determine the number of root commits")?
-                .parse::<u32>()?)
-        };
-        let num_roots_before = num_roots()?;
-
-        let sha =
-            cmd!(sh, "git rev-parse HEAD").output().context("FAILED to get current commit")?.stdout;
-
-        // Merge the fetched commit.
-        const MERGE_COMMIT_MESSAGE: &str = "Merge from rustc";
-        cmd!(sh, "git merge FETCH_HEAD --no-verify --no-ff -m {MERGE_COMMIT_MESSAGE}")
-            .run()
-            .context("FAILED to merge new commits, something went wrong")?;
-
-        let current_sha =
-            cmd!(sh, "git rev-parse HEAD").output().context("FAILED to get current commit")?.stdout;
-        if current_sha == sha {
-            cmd!(sh, "git reset --hard HEAD^")
-                .run()
-                .expect("FAILED to clean up after creating the preparation commit");
-            eprintln!(
-                "No merge was performed, no changes to pull were found. Rolled back the preparation commit."
-            );
-            return Err(RustcPullError::NothingToPull);
-        }
-
-        // Check that the number of roots did not increase.
-        if num_roots()? != num_roots_before {
-            return Err(anyhow::anyhow!(
-                "Josh created a new root commit. This is probably not the history you want."
-            )
-            .into());
-        }
-
-        drop(josh);
-        Ok(())
-    }
-
-    pub fn rustc_push(&self, github_user: String, branch: String) -> anyhow::Result<()> {
-        let sh = Shell::new()?;
-        sh.change_dir(&self.dir);
-        let base = sh.read_file("rust-version")?.trim().to_owned();
-        // Make sure the repo is clean.
-        if cmd!(sh, "git status --untracked-files=no --porcelain").read()?.is_empty().not() {
-            bail!("working directory must be clean before running `rustc-push`");
-        }
-        // Make sure josh is running.
-        let josh = Self::start_josh()?;
-        let josh_url =
-            format!("http://localhost:{JOSH_PORT}/{github_user}/rust.git{JOSH_FILTER}.git");
-
-        // Find a repo we can do our preparation in.
-        if let Ok(rustc_git) = env::var("RUSTC_GIT") {
-            // If rustc_git is `Some`, we'll use an existing fork for the branch updates.
-            sh.change_dir(rustc_git);
-        } else {
-            // Otherwise, do this in the local repo.
-            println!(
-                "This will pull a copy of the rust-lang/rust history into this checkout, growing it by about 1GB."
-            );
-            print!(
-                "To avoid that, abort now and set the `RUSTC_GIT` environment variable to an existing rustc checkout. Proceed? [y/N] "
-            );
-            std::io::stdout().flush()?;
-            let mut answer = String::new();
-            std::io::stdin().read_line(&mut answer)?;
-            if answer.trim().to_lowercase() != "y" {
-                std::process::exit(1);
-            }
-        };
-        // Prepare the branch. Pushing works much better if we use as base exactly
-        // the commit that we pulled from last time, so we use the `rust-version`
-        // file to find out which commit that would be.
-        println!("Preparing {github_user}/rust (base: {base})...");
-        if cmd!(sh, "git fetch https://github.com/{github_user}/rust {branch}")
-            .ignore_stderr()
-            .read()
-            .is_ok()
-        {
-            println!(
-                "The branch '{branch}' seems to already exist in 'https://github.com/{github_user}/rust'. Please delete it and try again."
-            );
-            std::process::exit(1);
-        }
-        cmd!(sh, "git fetch https://github.com/{UPSTREAM_REPO} {base}").run()?;
-        cmd!(sh, "git push https://github.com/{github_user}/rust {base}:refs/heads/{branch}")
-            .ignore_stdout()
-            .ignore_stderr() // silence the "create GitHub PR" message
-            .run()?;
-        println!();
-
-        // Do the actual push.
-        sh.change_dir(&self.dir);
-        println!("Pushing changes...");
-        cmd!(sh, "git push {josh_url} HEAD:{branch}").run()?;
-        println!();
-
-        // Do a round-trip check to make sure the push worked as expected.
-        cmd!(sh, "git fetch {josh_url} {branch}").ignore_stderr().read()?;
-        let head = cmd!(sh, "git rev-parse HEAD").read()?;
-        let fetch_head = cmd!(sh, "git rev-parse FETCH_HEAD").read()?;
-        if head != fetch_head {
-            bail!(
-                "Josh created a non-roundtrip push! Do NOT merge this into rustc!\n\
-                Expected {head}, got {fetch_head}."
-            );
-        }
-        println!(
-            "Confirmed that the push round-trips back to rustc-dev-guide properly. Please create a rustc PR:"
-        );
-        println!(
-            // Open PR with `subtree update` title to silence the `no-merges` triagebot check
-            "    https://github.com/{UPSTREAM_REPO}/compare/{github_user}:{branch}?quick_pull=1&title=rustc-dev-guide+subtree+update&body=r?+@ghost"
-        );
-
-        drop(josh);
-        Ok(())
-    }
-
-    fn start_josh() -> anyhow::Result<impl Drop> {
-        // Determine cache directory.
-        let local_dir = {
-            let user_dirs =
-                directories::ProjectDirs::from("org", "rust-lang", "rustc-dev-guide-josh").unwrap();
-            user_dirs.cache_dir().to_owned()
-        };
-
-        // Start josh, silencing its output.
-        let mut cmd = process::Command::new("josh-proxy");
-        cmd.arg("--local").arg(local_dir);
-        cmd.arg("--remote").arg("https://github.com");
-        cmd.arg("--port").arg(JOSH_PORT.to_string());
-        cmd.arg("--no-background");
-        cmd.stdout(process::Stdio::null());
-        cmd.stderr(process::Stdio::null());
-        let josh = cmd.spawn().context("failed to start josh-proxy, make sure it is installed")?;
-
-        // Create a wrapper that stops it on drop.
-        struct Josh(process::Child);
-        impl Drop for Josh {
-            fn drop(&mut self) {
-                #[cfg(unix)]
-                {
-                    // Try to gracefully shut it down.
-                    process::Command::new("kill")
-                        .args(["-s", "INT", &self.0.id().to_string()])
-                        .output()
-                        .expect("failed to SIGINT josh-proxy");
-                    // Sadly there is no "wait with timeout"... so we just give it some time to finish.
-                    std::thread::sleep(Duration::from_millis(100));
-                    // Now hopefully it is gone.
-                    if self.0.try_wait().expect("failed to wait for josh-proxy").is_some() {
-                        return;
-                    }
-                }
-                // If that didn't work (or we're not on Unix), kill it hard.
-                eprintln!(
-                    "I have to kill josh-proxy the hard way, let's hope this does not break anything."
-                );
-                self.0.kill().expect("failed to SIGKILL josh-proxy");
-            }
-        }
-
-        // Wait until the port is open. We try every 10ms until 1s passed.
-        for _ in 0..100 {
-            // This will generally fail immediately when the port is still closed.
-            let josh_ready = net::TcpStream::connect_timeout(
-                &net::SocketAddr::from(([127, 0, 0, 1], JOSH_PORT)),
-                Duration::from_millis(1),
-            );
-            if josh_ready.is_ok() {
-                return Ok(Josh(josh));
-            }
-            // Not ready yet.
-            std::thread::sleep(Duration::from_millis(10));
-        }
-        bail!("Even after waiting for 1s, josh-proxy is still not available.")
-    }
-}
diff --git a/src/doc/rustc-dev-guide/rust-version b/src/doc/rustc-dev-guide/rust-version
index e444613e631..3f10132b684 100644
--- a/src/doc/rustc-dev-guide/rust-version
+++ b/src/doc/rustc-dev-guide/rust-version
@@ -1 +1 @@
-c96a69059ecc618b519da385a6ccd03155aa0237
+fd2eb391d032181459773f3498c17b198513e0d0
diff --git a/src/doc/rustc-dev-guide/src/SUMMARY.md b/src/doc/rustc-dev-guide/src/SUMMARY.md
index 7f2f32c62ff..651e2925ad5 100644
--- a/src/doc/rustc-dev-guide/src/SUMMARY.md
+++ b/src/doc/rustc-dev-guide/src/SUMMARY.md
@@ -35,7 +35,6 @@
         - [Cranelift codegen backend](./tests/codegen-backend-tests/cg_clif.md)
         - [GCC codegen backend](./tests/codegen-backend-tests/cg_gcc.md)
     - [Performance testing](./tests/perf.md)
-    - [Suggest tests tool](./tests/suggest-tests.md)
     - [Misc info](./tests/misc.md)
 - [Debugging the compiler](./compiler-debugging.md)
     - [Using the tracing/logging instrumentation](./tracing.md)
diff --git a/src/doc/rustc-dev-guide/src/autodiff/installation.md b/src/doc/rustc-dev-guide/src/autodiff/installation.md
index c9b28dc43a6..a550f6d233e 100644
--- a/src/doc/rustc-dev-guide/src/autodiff/installation.md
+++ b/src/doc/rustc-dev-guide/src/autodiff/installation.md
@@ -6,14 +6,14 @@ In the near future, `std::autodiff` should become available in nightly builds fo
 
 First you need to clone and configure the Rust repository:
 ```bash
-git clone --depth=1 git@github.com:rust-lang/rust.git
+git clone git@github.com:rust-lang/rust
 cd rust
 ./configure --enable-llvm-link-shared --enable-llvm-plugins --enable-llvm-enzyme --release-channel=nightly --enable-llvm-assertions --enable-clang --enable-lld --enable-option-checking --enable-ninja --disable-docs
 ```
 
 Afterwards you can build rustc using:
 ```bash
-./x.py build --stage 1 library
+./x build --stage 1 library
 ```
 
 Afterwards rustc toolchain link will allow you to use it through cargo:
@@ -25,10 +25,10 @@ rustup toolchain install nightly # enables -Z unstable-options
 You can then run our test cases:
 
 ```bash
-./x.py test --stage 1 tests/codegen/autodiff
-./x.py test --stage 1 tests/pretty/autodiff
-./x.py test --stage 1 tests/ui/autodiff
-./x.py test --stage 1 tests/ui/feature-gates/feature-gate-autodiff.rs
+./x test --stage 1 tests/codegen/autodiff
+./x test --stage 1 tests/pretty/autodiff
+./x test --stage 1 tests/ui/autodiff
+./x test --stage 1 tests/ui/feature-gates/feature-gate-autodiff.rs
 ```
 
 Autodiff is still experimental, so if you want to use it in your own projects, you will need to add `lto="fat"` to your Cargo.toml 
@@ -45,7 +45,7 @@ apt install wget vim python3 git curl libssl-dev pkg-config lld ninja-build cmak
 ```
 Then build rustc in a slightly altered way:
 ```bash
-git clone --depth=1 https://github.com/rust-lang/rust.git
+git clone https://github.com/rust-lang/rust
 cd rust
 ./configure --enable-llvm-link-shared --enable-llvm-plugins --enable-llvm-enzyme --release-channel=nightly --enable-llvm-assertions --enable-clang --enable-lld --enable-option-checking --enable-ninja --disable-docs
 ./x dist
@@ -66,7 +66,7 @@ We recommend that approach, if you just want to use any of them and have no expe
 However, if you prefer to just build Enzyme without Rust, then these instructions might help.
 
 ```bash
-git clone --depth=1 git@github.com:llvm/llvm-project.git 
+git clone git@github.com:llvm/llvm-project
 cd llvm-project
 mkdir build
 cd build
@@ -77,7 +77,7 @@ ninja install
 This gives you a working LLVM build, now we can continue with building Enzyme.
 Leave the `llvm-project` folder, and execute the following commands:
 ```bash
-git clone git@github.com:EnzymeAD/Enzyme.git 
+git clone git@github.com:EnzymeAD/Enzyme
 cd Enzyme/enzyme
 mkdir build 
 cd build 
diff --git a/src/doc/rustc-dev-guide/src/building/quickstart.md b/src/doc/rustc-dev-guide/src/building/quickstart.md
index 9a8ab353e02..97314d80369 100644
--- a/src/doc/rustc-dev-guide/src/building/quickstart.md
+++ b/src/doc/rustc-dev-guide/src/building/quickstart.md
@@ -61,9 +61,6 @@ and check the output.
 Use `--bless` if you've made a change and want to update the `.stderr` files
 with the new output.
 
-> `./x suggest` can also be helpful for suggesting which tests to run after a
-> change.
-
 Congrats, you are now ready to make a change to the compiler! If you have more
 questions, [the full chapter](./how-to-build-and-run.md) might contain the
 answers, and if it doesn't, feel free to ask for help on
diff --git a/src/doc/rustc-dev-guide/src/building/suggested.md b/src/doc/rustc-dev-guide/src/building/suggested.md
index bfb2f4d1084..7f626314f71 100644
--- a/src/doc/rustc-dev-guide/src/building/suggested.md
+++ b/src/doc/rustc-dev-guide/src/building/suggested.md
@@ -270,23 +270,6 @@ run the tests at some later time. You can then use `git bisect` to track down
 is that you are left with a fairly fine-grained set of commits at the end, all
 of which build and pass tests. This often helps reviewing.
 
-## `x suggest`
-
-The `x suggest` subcommand suggests (and runs) a subset of the extensive
-`rust-lang/rust` tests based on files you have changed. This is especially
-useful for new contributors who have not mastered the arcane `x` flags yet and
-more experienced contributors as a shorthand for reducing mental effort. In all
-cases it is useful not to run the full tests (which can take on the order of
-tens of minutes) and just run a subset which are relevant to your changes. For
-example, running `tidy` and `linkchecker` is useful when editing Markdown files,
-whereas UI tests are much less likely to be helpful. While `x suggest` is a
-useful tool, it does not guarantee perfect coverage (just as PR CI isn't a
-substitute for bors). See the [dedicated chapter](../tests/suggest-tests.md) for
-more information and contribution instructions.
-
-Please note that `x suggest` is in a beta state currently and the tests that it
-will suggest are limited.
-
 ## Configuring `rustup` to use nightly
 
 Some parts of the bootstrap process uses pinned, nightly versions of tools like
diff --git a/src/doc/rustc-dev-guide/src/effects.md b/src/doc/rustc-dev-guide/src/effects.md
index c7aa2714668..87b0103a7bc 100644
--- a/src/doc/rustc-dev-guide/src/effects.md
+++ b/src/doc/rustc-dev-guide/src/effects.md
@@ -67,10 +67,8 @@ in [`wfcheck::check_impl`].
 Here's an example:
 
 ```rust
-#[const_trait]
-trait Bar {}
-#[const_trait]
-trait Foo: ~const Bar {}
+const trait Bar {}
+const trait Foo: ~const Bar {}
 // `const_conditions` contains `HostEffect(Self: Bar, maybe)`
 
 impl const Bar for () {}
@@ -85,8 +83,7 @@ predicates of the trait method, and we attempt to prove the predicates of the
 impl method. We do the same for `const_conditions`:
 
 ```rust
-#[const_trait]
-trait Foo {
+const trait Foo {
     fn hi<T: ~const Default>();
 }
 
diff --git a/src/doc/rustc-dev-guide/src/external-repos.md b/src/doc/rustc-dev-guide/src/external-repos.md
index f3170c9222d..ecc65b26ab7 100644
--- a/src/doc/rustc-dev-guide/src/external-repos.md
+++ b/src/doc/rustc-dev-guide/src/external-repos.md
@@ -9,7 +9,7 @@ There are three main ways we use dependencies:
 As a general rule:
 - Use crates.io for libraries that could be useful for others in the ecosystem
 - Use subtrees for tools that depend on compiler internals and need to be updated if there are breaking
-changes
+  changes
 - Use submodules for tools that are independent of the compiler
 
 ## External Dependencies (subtrees)
@@ -23,6 +23,8 @@ The following external projects are managed using some form of a `subtree`:
 * [rust-analyzer](https://github.com/rust-lang/rust-analyzer)
 * [rustc_codegen_cranelift](https://github.com/rust-lang/rustc_codegen_cranelift)
 * [rustc-dev-guide](https://github.com/rust-lang/rustc-dev-guide)
+* [compiler-builtins](https://github.com/rust-lang/compiler-builtins)
+* [stdarch](https://github.com/rust-lang/stdarch)
 
 In contrast to `submodule` dependencies
 (see below for those), the `subtree` dependencies are just regular files and directories which can
@@ -34,20 +36,61 @@ implement a new tool feature or test, that should happen in one collective rustc
 `subtree` dependencies are currently managed by two distinct approaches:
 
 * Using `git subtree`
-  * `clippy` ([sync guide](https://doc.rust-lang.org/nightly/clippy/development/infrastructure/sync.html#performing-the-sync-from-rust-langrust-to-clippy))
-  * `portable-simd` ([sync script](https://github.com/rust-lang/portable-simd/blob/master/subtree-sync.sh))
-  * `rustfmt`
-  * `rustc_codegen_cranelift` ([sync script](https://github.com/rust-lang/rustc_codegen_cranelift/blob/113af154d459e41b3dc2c5d7d878e3d3a8f33c69/scripts/rustup.sh#L7))
+    * `clippy` ([sync guide](https://doc.rust-lang.org/nightly/clippy/development/infrastructure/sync.html#performing-the-sync-from-rust-langrust-to-clippy))
+    * `portable-simd` ([sync script](https://github.com/rust-lang/portable-simd/blob/master/subtree-sync.sh))
+    * `rustfmt`
+    * `rustc_codegen_cranelift` ([sync script](https://github.com/rust-lang/rustc_codegen_cranelift/blob/113af154d459e41b3dc2c5d7d878e3d3a8f33c69/scripts/rustup.sh#L7))
 * Using the [josh] tool
-  * `miri` ([sync guide](https://github.com/rust-lang/miri/blob/master/CONTRIBUTING.md#advanced-topic-syncing-with-the-rustc-repo))
-  * `rust-analyzer` ([sync script](https://github.com/rust-lang/rust-analyzer/blob/2e13684be123eca7181aa48e043e185d8044a84a/xtask/src/release.rs#L147))
-  * `rustc-dev-guide` ([sync guide](https://github.com/rust-lang/rustc-dev-guide#synchronizing-josh-subtree-with-rustc))
+    * `miri` ([sync guide](https://github.com/rust-lang/miri/blob/master/CONTRIBUTING.md#advanced-topic-syncing-with-the-rustc-repo))
+    * `rust-analyzer` ([sync script](https://github.com/rust-lang/rust-analyzer/blob/2e13684be123eca7181aa48e043e185d8044a84a/xtask/src/release.rs#L147))
+    * `rustc-dev-guide` ([josh sync](#synchronizing-a-josh-subtree))
+    * `compiler-builtins` ([josh sync](#synchronizing-a-josh-subtree))
+    * `stdarch` ([josh sync](#synchronizing-a-josh-subtree))
 
-The [josh] tool is an alternative to git subtrees, which manages git history in a different way and scales better to larger repositories. Specific tooling is required to work with josh, you can check out the `miri` or `rust-analyzer` scripts linked above for inspiration. If you want to migrate a repository dependency from `git subtree` or `git submodule` to josh, you can check out [this guide](https://hackmd.io/7pOuxnkdQDaL1Y1FQr65xg).
+### Josh subtrees
 
-Below you can find a guide on how to perform push and pull synchronization with the main rustc repo using `git subtree`, although these instructions might differ repo from repo.
+The [josh] tool is an alternative to git subtrees, which manages git history in a different way and scales better to larger repositories. Specific tooling is required to work with josh; you can check out the `miri` or `rust-analyzer` scripts linked above for inspiration. We provide a helper [`rustc-josh-sync`][josh-sync] tool to help with the synchronization, described [below](#synchronizing-a-josh-subtree).
 
-### Synchronizing a subtree
+### Synchronizing a Josh subtree
+
+We use a dedicated tool called [`rustc-josh-sync`][josh-sync] for performing Josh subtree updates.
+Currently, we are migrating Josh repositories to it. So far, it is used in:
+
+- compiler-builtins
+- rustc-dev-guide
+- stdarch
+
+To install the tool:
+```
+cargo install --locked --git https://github.com/rust-lang/josh-sync
+```
+
+Both pulls (synchronize changes from rust-lang/rust into the subtree) and pushes (synchronize
+changes from the subtree to rust-lang/rust) are performed from the subtree repository (so first
+switch to its repository checkout directory in your terminal).
+
+#### Performing pull
+1) Checkout a new branch that will be used to create a PR into the subtree
+2) Run the pull command
+    ```
+    rustc-josh-sync pull
+    ```
+3) Push the branch to your fork and create a PR into the subtree repository
+    - If you have `gh` CLI installed, `rustc-josh-sync` can create the PR for you.
+
+#### Performing push
+
+1) Run the push command to create a branch named `<branch-name>` in a `rustc` fork under the `<gh-username>` account
+    ```
+    rustc-josh-sync push <branch-name> <gh-username>
+    ```
+2) Create a PR from `<branch-name>` into `rust-lang/rust`
+
+### Creating a new Josh subtree dependency
+
+If you want to migrate a repository dependency from `git subtree` or `git submodule` to josh, you can check out [this guide](https://hackmd.io/7pOuxnkdQDaL1Y1FQr65xg).
+
+### Synchronizing a git subtree
 
 Periodically the changes made to subtree based dependencies need to be synchronized between this
 repository and the upstream tool repositories.
@@ -129,3 +172,4 @@ the week leading up to the beta cut.
 [toolstate website]: https://rust-lang-nursery.github.io/rust-toolstate/
 [Toolstate chapter]: https://forge.rust-lang.org/infra/toolstate.html
 [josh]: https://josh-project.github.io/josh/intro.html
+[josh-sync]: https://github.com/rust-lang/josh-sync
diff --git a/src/doc/rustc-dev-guide/src/offload/installation.md b/src/doc/rustc-dev-guide/src/offload/installation.md
index 2536af09a23..1962314c70a 100644
--- a/src/doc/rustc-dev-guide/src/offload/installation.md
+++ b/src/doc/rustc-dev-guide/src/offload/installation.md
@@ -6,14 +6,14 @@ In the future, `std::offload` should become available in nightly builds for user
 
 First you need to clone and configure the Rust repository:
 ```bash
-git clone --depth=1 git@github.com:rust-lang/rust.git
+git clone git@github.com:rust-lang/rust
 cd rust
 ./configure --enable-llvm-link-shared --release-channel=nightly --enable-llvm-assertions --enable-offload --enable-enzyme --enable-clang --enable-lld --enable-option-checking --enable-ninja --disable-docs
 ```
 
 Afterwards you can build rustc using:
 ```bash
-./x.py build --stage 1 library
+./x build --stage 1 library
 ```
 
 Afterwards rustc toolchain link will allow you to use it through cargo:
@@ -26,7 +26,7 @@ rustup toolchain install nightly # enables -Z unstable-options
 
 ## Build instruction for LLVM itself
 ```bash
-git clone --depth=1 git@github.com:llvm/llvm-project.git 
+git clone git@github.com:llvm/llvm-project
 cd llvm-project
 mkdir build
 cd build
@@ -40,7 +40,7 @@ This gives you a working LLVM build.
 ## Testing
 run
 ```
-./x.py test --stage 1 tests/codegen/gpu_offload
+./x test --stage 1 tests/codegen/gpu_offload
 ```
 
 ## Usage
diff --git a/src/doc/rustc-dev-guide/src/solve/invariants.md b/src/doc/rustc-dev-guide/src/solve/invariants.md
index fd12b195757..8ec15f339e5 100644
--- a/src/doc/rustc-dev-guide/src/solve/invariants.md
+++ b/src/doc/rustc-dev-guide/src/solve/invariants.md
@@ -4,17 +4,15 @@ FIXME: This file talks about invariants of the type system as a whole, not only
 
 There are a lot of invariants - things the type system guarantees to be true at all times -
 which are desirable or expected from other languages and type systems. Unfortunately, quite
-a few of them do not hold in Rust right now. This is either a fundamental to its design or
-caused by bugs and something that may change in the future.
+a few of them do not hold in Rust right now. This is either fundamental to its design or
+caused by bugs, and something that may change in the future.
 
-It is important to know about the things you can assume while working on - and with - the
+It is important to know about the things you can assume while working on, and with, the
 type system, so here's an incomplete and unofficial list of invariants of
 the core type system:
 
-- ✅: this invariant mostly holds, with some weird exceptions, you can rely on it outside
-of these cases
-- ❌: this invariant does not hold, either due to bugs or by design, you must not rely on
-it for soundness or have to be incredibly careful when doing so
+- ✅: this invariant mostly holds, with some weird exceptions or current bugs
+- ❌: this invariant does not hold, and is unlikely to do so in the future; do not rely on it for soundness or have to be incredibly careful when doing so
 
 ### `wf(X)` implies `wf(normalize(X))` ✅
 
@@ -23,20 +21,23 @@ well-formed after normalizing said aliases. We rely on this as
 otherwise we would have to re-check for well-formedness for these
 types.
 
+This currently does not hold due to a type system unsoundness: [#84533](https://github.com/rust-lang/rust/issues/84533).
+
 ### Structural equality modulo regions implies semantic equality ✅
 
 If you have a some type and equate it to itself after replacing any regions with unique
 inference variables in both the lhs and rhs, the now potentially structurally different
 types should still be equal to each other.
 
-Needed to prevent goals from succeeding in HIR typeck and then failing in MIR borrowck.
-If this invariant is broken MIR typeck ends up failing with an ICE.
+This is needed to prevent goals from succeeding in HIR typeck and then failing in MIR borrowck.
+If this invariant is broken, MIR typeck ends up failing with an ICE.
 
 ### Applying inference results from a goal does not change its result ❌
 
 TODO: this invariant is formulated in a weird way and needs to be elaborated.
 Pretty much: I would like this check to only fail if there's a solver bug:
-https://github.com/rust-lang/rust/blob/2ffeb4636b4ae376f716dc4378a7efb37632dc2d/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs#L391-L407
+<https://github.com/rust-lang/rust/blob/2ffeb4636b4ae376f716dc4378a7efb37632dc2d/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs#L391-L407>.
+We should readd this check and see where it breaks :3
 
 If we prove some goal/equate types/whatever, apply the resulting inference constraints,
 and then redo the original action, the result should be the same.
@@ -73,82 +74,99 @@ Many of the currently known unsound issues end up relying on this invariant bein
 It is however very difficult to imagine a sound type system without this invariant, so
 the issue is that the invariant is broken, not that we incorrectly rely on it.
 
-### Generic goals and their instantiations have the same result ✅
+### The type system is complete ❌
+
+The type system is not complete.
+It often adds unnecessary inference constraints, and errors even though the goal could hold.
+
+- method selection
+- opaque type inference
+- handling type outlives constraints
+- preferring `ParamEnv` candidates over `Impl` candidates during candidate selection
+in the trait solver
+
+### Goals keep their result from HIR typeck afterwards ✅
+
+Having a goal which succeeds during HIR typeck but fails when being reevaluated during MIR borrowck causes ICE, e.g. [#140211](https://github.com/rust-lang/rust/issues/140211).
 
-Pretty much: If we successfully typecheck a generic function concrete instantiations
-of that function should also typeck. We should not get errors post-monomorphization.
-We can however get overflow errors at that point.
+Having a goal which succeeds during HIR typeck but fails after being instantiated is unsound, e.g. [#140212](https://github.com/rust-lang/rust/issues/140212).
 
-TODO: example for overflow error post-monomorphization
+It is interesting that we allow some incompleteness in the trait solver while still maintaining this limitation. It would be nice if there was a clear way to separate the "allowed incompleteness" from behavior which would break this invariant.
+
+#### Normalization must not change results
 
 This invariant is relied on to allow the normalization of generic aliases. Breaking
-it can easily result in unsoundness, e.g. [#57893](https://github.com/rust-lang/rust/issues/57893)
+it can easily result in unsoundness, e.g. [#57893](https://github.com/rust-lang/rust/issues/57893).
+
+#### Goals may still overflow after instantiation
+
+This happens they start to hit the recursion limit.
+We also have diverging aliases which are scuffed.
+It's unclear how these should be handled :3
 
 ### Trait goals in empty environments are proven by a unique impl ✅
 
 If a trait goal holds with an empty environment, there should be a unique `impl`,
 either user-defined or builtin, which is used to prove that goal. This is
-necessary to select a unique method.
+necessary to select unique methods and associated items.
 
-We do however break this invariant in few cases, some of which are due to bugs,
-some by design:
+We do however break this invariant in a few cases, some of which are due to bugs, some by design:
 - *marker traits* are allowed to overlap as they do not have associated items
 - *specialization* allows specializing impls to overlap with their parent
 - the builtin trait object trait implementation can overlap with a user-defined impl:
-[#57893]
+[#57893](https://github.com/rust-lang/rust/issues/57893)
 
-### The type system is complete ❌
-
-The type system is not complete, it often adds unnecessary inference constraints, and errors
-even though the goal could hold.
-
-- method selection
-- opaque type inference
-- handling type outlives constraints
-- preferring `ParamEnv` candidates over `Impl` candidates during candidate selection
-in the trait solver
 
 #### The type system is complete during the implicit negative overlap check in coherence ✅
 
-For more on overlap checking: [coherence]
+For more on overlap checking, see [Coherence chapter].
 
-During the implicit negative overlap check in coherence we must never return *error* for
-goals which can be proven. This would allow for overlapping impls with potentially different
-associated items, breaking a bunch of other invariants.
+During the implicit negative overlap check in coherence,
+we must never return *error* for goals which can be proven.
+This would allow for overlapping impls with potentially different associated items,
+breaking a bunch of other invariants.
 
 This invariant is currently broken in many different ways while actually something we rely on.
 We have to be careful as it is quite easy to break:
 - generalization of aliases
 - generalization during subtyping binders (luckily not exploitable in coherence)
 
-### Trait solving must be (free) lifetime agnostic ✅
+### Trait solving must not depend on lifetimes being different ✅
+
+If a goal holds with lifetimes being different, it must also hold with these lifetimes being the same. We otherwise get post-monomorphization errors during codegen or unsoundness due to invalid vtables.
 
-Trait solving during codegen should have the same result as during typeck. As we erase
-all free regions during codegen we must not rely on them during typeck. A noteworthy example
-is special behavior for `'static`.
+We could also just get inconsistent behavior when first proving a goal with different lifetimes which are later constrained to be equal.
+
+### Trait solving in bodies must not depend on lifetimes being equal ✅
 
 We also have to be careful with relying on equality of regions in the trait solver.
 This is fine for codegen, as we treat all erased regions as equal. We can however
 lose equality information from HIR to MIR typeck.
 
-The new solver "uniquifies regions" during canonicalization, canonicalizing `u32: Trait<'x, 'x>`
-as `exists<'0, '1> u32: Trait<'0, '1>`, to make it harder to rely on this property.
+This currently does not hold with the new solver: [trait-system-refactor-initiative#27](https://github.com/rust-lang/trait-system-refactor-initiative/issues/27).
 
 ### Removing ambiguity makes strictly more things compile ❌
 
 Ideally we *should* not rely on ambiguity for things to compile.
 Not doing that will cause future improvements to be breaking changes.
 
-Due to *incompleteness* this is not the case and improving inference can result in inference
-changes, breaking existing projects.
+Due to *incompleteness* this is not the case,
+and improving inference can result in inference changes, breaking existing projects.
 
 ### Semantic equality implies structural equality ✅
 
 Two types being equal in the type system must mean that they have the
 same `TypeId` after instantiating their generic parameters with concrete
-arguments. This currently does not hold: [#97156].
+arguments. We can otherwise use their different `TypeId`s to impact trait selection.
+
+We lookup types using structural equality during codegen, but this shouldn't necessarily be unsound
+- may result in redundant method codegen or backend type check errors?
+- we also rely on it in CTFE assertions
+
+### Semantically different types have different `TypeId`s ✅
+
+Semantically different `'static` types need different `TypeId`s to avoid transmutes,
+for example `for<'a> fn(&'a str)` vs `fn(&'static str)` must have a different `TypeId`.
+
 
-[#57893]: https://github.com/rust-lang/rust/issues/57893
-[#97156]: https://github.com/rust-lang/rust/issues/97156
-[#114936]: https://github.com/rust-lang/rust/issues/114936
-[coherence]:  ../coherence.md
+[coherence chapter]: ../coherence.md
diff --git a/src/doc/rustc-dev-guide/src/tests/directives.md b/src/doc/rustc-dev-guide/src/tests/directives.md
index 839076b809d..5c3ae359ba0 100644
--- a/src/doc/rustc-dev-guide/src/tests/directives.md
+++ b/src/doc/rustc-dev-guide/src/tests/directives.md
@@ -59,7 +59,7 @@ not be exhaustive. Directives can generally be found by browsing the
 | `aux-crate`           | Like `aux-build` but makes available as extern prelude                                                | All except `run-make` | `<extern_prelude_name>=<path/to/aux/file.rs>` |
 | `aux-codegen-backend` | Similar to `aux-build` but pass the compiled dylib to `-Zcodegen-backend` when building the main file | `ui-fulldeps`         | Path to codegen backend file                  |
 | `proc-macro`          | Similar to `aux-build`, but for aux forces host and don't use `-Cprefer-dynamic`[^pm].                | All except `run-make` | Path to auxiliary proc-macro `.rs` file       |
-| `build-aux-docs`      | Build docs for auxiliaries as well                                                                    | All except `run-make` | N/A                                           |
+| `build-aux-docs`      | Build docs for auxiliaries as well.  Note that this only works with `aux-build`, not `aux-crate`.     | All except `run-make` | N/A                                           |
 
 [^pm]: please see the Auxiliary proc-macro section in the
     [compiletest](./compiletest.md) chapter for specifics.
@@ -75,8 +75,10 @@ expectations](ui.md#controlling-passfail-expectations).
 | `check-fail`                | Building (no codegen) should fail           | `ui`, `crashes`                           | N/A             |
 | `build-pass`                | Building should pass                        | `ui`, `crashes`, `codegen`, `incremental` | N/A             |
 | `build-fail`                | Building should fail                        | `ui`, `crashes`                           | N/A             |
-| `run-pass`                  | Running the test binary should pass         | `ui`, `crashes`, `incremental`            | N/A             |
-| `run-fail`                  | Running the test binary should fail         | `ui`, `crashes`                           | N/A             |
+| `run-pass`                  | Program must exit with code `0`             | `ui`, `crashes`, `incremental`            | N/A             |
+| `run-fail`                  | Program must exit with code `1..=127`       | `ui`, `crashes`                           | N/A             |
+| `run-crash`                 | Program must crash                          | `ui`                                      | N/A             |
+| `run-fail-or-crash`         | Program must `run-fail` or `run-crash`      | `ui`                                      | N/A             |
 | `ignore-pass`               | Ignore `--pass` flag                        | `ui`, `crashes`, `codegen`, `incremental` | N/A             |
 | `dont-check-failure-status` | Don't check exact failure status (i.e. `1`) | `ui`, `incremental`                       | N/A             |
 | `failure-status`            | Check                                       | `ui`, `crashes`                           | Any `u16`       |
@@ -203,6 +205,8 @@ settings:
   on `wasm32-unknown-unknown` target because the target does not support the
   `proc-macro` crate type.
 - `needs-target-std` — ignores if target platform does not have std support.
+- `ignore-backends` — ignores the listed backends, separated by whitespace characters.
+- `needs-backends` — only runs the test if current codegen backend is listed.
 
 The following directives will check LLVM support:
 
diff --git a/src/doc/rustc-dev-guide/src/tests/intro.md b/src/doc/rustc-dev-guide/src/tests/intro.md
index c55d60f4a5c..79b96c450a8 100644
--- a/src/doc/rustc-dev-guide/src/tests/intro.md
+++ b/src/doc/rustc-dev-guide/src/tests/intro.md
@@ -111,12 +111,14 @@ and it can be invoked so:
 
 This requires building all of the documentation, which might take a while.
 
-### Dist check
+### `distcheck`
 
 `distcheck` verifies that the source distribution tarball created by the build
 system will unpack, build, and run all tests.
 
-> Example: `./x test distcheck`
+```console
+./x test distcheck
+```
 
 ### Tool tests
 
diff --git a/src/doc/rustc-dev-guide/src/tests/misc.md b/src/doc/rustc-dev-guide/src/tests/misc.md
index c0288b3dd10..39f88174879 100644
--- a/src/doc/rustc-dev-guide/src/tests/misc.md
+++ b/src/doc/rustc-dev-guide/src/tests/misc.md
@@ -9,7 +9,7 @@ for testing:
 
 - `RUSTC_BOOTSTRAP=1` will "cheat" and bypass usual stability checking, allowing
   you to use unstable features and cli flags on a stable `rustc`.
-- `RUSTC_BOOTSTRAP=-1` will force a given `rustc` to pretend that is a stable
+- `RUSTC_BOOTSTRAP=-1` will force a given `rustc` to pretend it is a stable
   compiler, even if it's actually a nightly `rustc`. This is useful because some
   behaviors of the compiler (e.g. diagnostics) can differ depending on whether
   the compiler is nightly or not.
diff --git a/src/doc/rustc-dev-guide/src/tests/suggest-tests.md b/src/doc/rustc-dev-guide/src/tests/suggest-tests.md
deleted file mode 100644
index 663e8a5af3b..00000000000
--- a/src/doc/rustc-dev-guide/src/tests/suggest-tests.md
+++ /dev/null
@@ -1,59 +0,0 @@
-# Suggest tests tool
-
-This chapter is about the internals of and contribution instructions for the
-`suggest-tests` tool. For a high-level overview of the tool, see [this
-section](../building/suggested.md#x-suggest). This tool is currently in a beta
-state and is tracked by [this](https://github.com/rust-lang/rust/issues/109933)
-issue on Github. Currently the number of tests it will suggest are very limited
-in scope, we are looking to expand this (contributions welcome!).
-
-## Internals
-
-The tool is defined in a separate crate
-([`src/tools/suggest-tests`](https://github.com/rust-lang/rust/blob/master/src/tools/suggest-tests))
-which outputs suggestions which are parsed by a shim in bootstrap
-([`src/bootstrap/src/core/build_steps/suggest.rs`](https://github.com/rust-lang/rust/blob/master/src/bootstrap/src/core/build_steps/suggest.rs)).
-The only notable thing the bootstrap shim does is (when invoked with the `--run`
-flag) use bootstrap's internal mechanisms to create a new `Builder` and uses it
-to invoke the suggested commands. The `suggest-tests` crate is where the fun
-happens, two kinds of suggestions are defined: "static" and "dynamic"
-suggestions.
-
-### Static suggestions
-
-Defined
-[here](https://github.com/rust-lang/rust/blob/master/src/tools/suggest-tests/src/static_suggestions.rs).
-Static suggestions are simple: they are just
-[globs](https://crates.io/crates/glob) which map to a `x` command. In
-`suggest-tests`, this is implemented with a simple `macro_rules` macro.
-
-### Dynamic suggestions
-
-Defined
-[here](https://github.com/rust-lang/rust/blob/master/src/tools/suggest-tests/src/dynamic_suggestions.rs).
-These are more complicated than static suggestions and are implemented as
-functions with the following signature: `fn(&Path) -> Vec<Suggestion>`. In other
-words, each suggestion takes a path to a modified file and (after running
-arbitrary Rust code) can return any number of suggestions, or none. Dynamic
-suggestions are useful for situations where fine-grained control over
-suggestions is needed. For example, modifications to the `compiler/xyz/` path
-should trigger the `x test compiler/xyz` suggestion. In the future, dynamic
-suggestions might even read file contents to determine if (what) tests should
-run.
-
-## Adding a suggestion
-
-The following steps should serve as a rough guide to add suggestions to
-`suggest-tests` (very welcome!):
-
-1. Determine the rules for your suggestion. Is it simple and operates only on a
-   single path or does it match globs? Does it need fine-grained control over
-   the resulting command or does "one size fit all"?
-2. Based on the previous step, decide if your suggestion should be implemented
-   as either static or dynamic.
-3. Implement the suggestion. If it is dynamic then a test is highly recommended,
-   to verify that your logic is correct and to give an example of the
-   suggestion. See the
-   [tests.rs](https://github.com/rust-lang/rust/blob/master/src/tools/suggest-tests/src/tests.rs)
-   file.
-4. Open a PR implementing your suggestion. **(TODO: add example PR)**
diff --git a/src/doc/rustc-dev-guide/src/tests/ui.md b/src/doc/rustc-dev-guide/src/tests/ui.md
index 4fce5838b6e..9bfc60e08a6 100644
--- a/src/doc/rustc-dev-guide/src/tests/ui.md
+++ b/src/doc/rustc-dev-guide/src/tests/ui.md
@@ -448,7 +448,7 @@ even run the resulting program. Just add one of the following
   - `//@ build-pass` — compilation and linking should succeed but do
     not run the resulting binary.
   - `//@ run-pass` — compilation should succeed and running the resulting
-    binary should also succeed.
+    binary should make it exit with code 0 which indicates success.
 - Fail directives:
   - `//@ check-fail` — compilation should fail (the codegen phase is skipped).
     This is the default for UI tests.
@@ -457,10 +457,20 @@ even run the resulting program. Just add one of the following
     - First time is to ensure that the compile succeeds without the codegen phase
     - Second time is to ensure that the full compile fails
   - `//@ run-fail` — compilation should succeed, but running the resulting
-    binary should fail.
-
-For `run-pass` and `run-fail` tests, by default the output of the program itself
-is not checked.
+    binary should make it exit with a code in the range `1..=127` which
+    indicates regular failure. On targets without unwind support, crashes
+    are also accepted.
+  - `//@ run-crash` — compilation should succeed, but running the resulting
+    binary should fail with a crash. Crashing is defined as "not exiting with
+    a code in the range `0..=127`". Example on Linux: Termination by `SIGABRT`
+    or `SIGSEGV`. Example on Windows: Exiting with the code for
+    `STATUS_ILLEGAL_INSTRUCTION` (`0xC000001D`).
+  - `//@ run-fail-or-crash` — compilation should succeed, but running the
+    resulting binary should either `run-fail` or `run-crash`. Useful if a test
+    crashes on some targets but just fails on others.
+
+For `run-pass`. `run-fail`, `run-crash` and `run-fail-or-crash` tests, by
+default the output of the program itself is not checked.
 
 If you want to check the output of running the program, include the
 `check-run-results` directive. This will check for a `.run.stderr` and
diff --git a/src/doc/rustc/src/exploit-mitigations.md b/src/doc/rustc/src/exploit-mitigations.md
index f8bafe03214..c80d7d8743c 100644
--- a/src/doc/rustc/src/exploit-mitigations.md
+++ b/src/doc/rustc/src/exploit-mitigations.md
@@ -54,17 +54,17 @@ Summary of exploit mitigations supported by the Rust compiler when building
 programs for the Linux operating system on the AMD64 architecture and
 equivalent.
 
-| Exploit mitigation | Supported and enabled by default | Since |
-| - | - | - |
-| Position-independent executable | Yes | 0.12.0 (2014-10-09) |
-| Integer overflow checks | Yes (enabled when debug assertions are enabled, and disabled when debug assertions are disabled) | 1.1.0 (2015-06-25) |
-| Non-executable memory regions | Yes | 1.8.0 (2016-04-14) |
-| Stack clashing protection | Yes | 1.20.0 (2017-08-31) |
-| Read-only relocations and immediate binding | Yes | 1.21.0 (2017-10-12) |
-| Heap corruption protection | Yes | 1.32.0 (2019-01-17) (via operating system default or specified allocator) |
-| Stack smashing protection | Yes | Nightly |
-| Forward-edge control flow protection | Yes | Nightly |
-| Backward-edge control flow protection (e.g., shadow and safe stack) | Yes | Nightly |
+| Exploit mitigation | Supported | Enabled by default | Since |
+| - | - | - | - |
+| Position-independent executable | Yes | Yes | 0.12.0 (2014-10-09) |
+| Integer overflow checks | Yes | (enabled when debug assertions are enabled, and disabled when debug assertions are disabled) | 1.1.0 (2015-06-25) |
+| Non-executable memory regions | Yes | Yes | 1.8.0 (2016-04-14) |
+| Stack clashing protection | Yes | Yes | 1.20.0 (2017-08-31) |
+| Read-only relocations and immediate binding | Yes | Yes | 1.21.0 (2017-10-12) |
+| Heap corruption protection | Yes | Yes | 1.32.0 (2019-01-17) (via operating system default or specified allocator) |
+| Stack smashing protection | Yes | No, `-Z stack-protector` | Nightly |
+| Forward-edge control flow protection | Yes | No, `-Z sanitizer=cfi` | Nightly |
+| Backward-edge control flow protection (e.g., shadow and safe stack) | Yes | No, `-Z sanitizer=shadow-call-stack,safestack` | Nightly |
 
 [^all-targets]: See <https://github.com/rust-lang/rust/tree/master/compiler/rustc_target/src/spec>
     for a list of targets and their default options.
diff --git a/src/doc/rustc/src/platform-support/netbsd.md b/src/doc/rustc/src/platform-support/netbsd.md
index e80ff85edad..b173bf82b44 100644
--- a/src/doc/rustc/src/platform-support/netbsd.md
+++ b/src/doc/rustc/src/platform-support/netbsd.md
@@ -32,10 +32,11 @@ are built for NetBSD 8.x but also work on newer OS versions).
 ## Target Maintainers
 
 [@he32](https://github.com/he32)
+[@0323pin](https://github.com/0323pin)
 
 Further contacts:
 
-- [NetBSD/pkgsrc-wip's rust](https://github.com/NetBSD/pkgsrc-wip/blob/master/rust185/Makefile) maintainer (see MAINTAINER variable). This package is part of "pkgsrc work-in-progress" and is used for deployment and testing of new versions of rust
+- [NetBSD/pkgsrc-wip's rust](https://github.com/NetBSD/pkgsrc-wip/blob/master/rust188/Makefile) maintainer (see MAINTAINER variable). This package is part of "pkgsrc work-in-progress" and is used for deployment and testing of new versions of rust.  Note that we have the convention of having multiple rust versions active in pkgsrc-wip at any one time, so the version number is part of the directory name, and from time to time old versions are culled so this is not a fully "stable" link.
 - [NetBSD's pkgsrc lang/rust](https://github.com/NetBSD/pkgsrc/tree/trunk/lang/rust) for the "proper" package in pkgsrc.
 - [NetBSD's pkgsrc lang/rust-bin](https://github.com/NetBSD/pkgsrc/tree/trunk/lang/rust-bin) which re-uses the bootstrap kit as a binary distribution and therefore avoids the rather protracted native build time of rust itself
 
diff --git a/src/doc/rustc/src/platform-support/xtensa.md b/src/doc/rustc/src/platform-support/xtensa.md
index 994b3adb92e..8592ce7eda9 100644
--- a/src/doc/rustc/src/platform-support/xtensa.md
+++ b/src/doc/rustc/src/platform-support/xtensa.md
@@ -24,4 +24,4 @@ Xtensa targets that support `std` are documented in the [ESP-IDF platform suppor
 
 ## Building the targets
 
-The targets can be built by installing the [Xtensa enabled Rust channel](https://github.com/esp-rs/rust/). See instructions in the [RISC-V and Xtensa Targets section of The Rust on ESP Book](https://docs.esp-rs.org/book/installation/riscv-and-xtensa.html).
+The targets can be built by installing the [Xtensa enabled Rust channel](https://github.com/esp-rs/rust/). See instructions in the [RISC-V and Xtensa Targets section of The Rust on ESP Book](https://docs.espressif.com/projects/rust/book/installation/index.html).
diff --git a/src/etc/completions/x.fish b/src/etc/completions/x.fish
index d3da1f353e2..28a228d5464 100644
--- a/src/etc/completions/x.fish
+++ b/src/etc/completions/x.fish
@@ -73,7 +73,6 @@ complete -c x -n "__fish_x_needs_command" -a "dist" -d 'Build distribution artif
 complete -c x -n "__fish_x_needs_command" -a "install" -d 'Install distribution artifacts'
 complete -c x -n "__fish_x_needs_command" -a "run" -d 'Run tools contained in this repository'
 complete -c x -n "__fish_x_needs_command" -a "setup" -d 'Set up the environment for development'
-complete -c x -n "__fish_x_needs_command" -a "suggest" -d 'Suggest a subset of tests to run, based on modified files'
 complete -c x -n "__fish_x_needs_command" -a "vendor" -d 'Vendor dependencies'
 complete -c x -n "__fish_x_needs_command" -a "perf" -d 'Perform profiling and benchmarking of the compiler using `rustc-perf`'
 complete -c x -n "__fish_x_using_subcommand build" -l config -d 'TOML configuration file for build' -r -F
@@ -599,42 +598,6 @@ complete -c x -n "__fish_x_using_subcommand setup" -l enable-bolt-settings -d 'E
 complete -c x -n "__fish_x_using_subcommand setup" -l skip-stage0-validation -d 'Skip stage0 compiler validation'
 complete -c x -n "__fish_x_using_subcommand setup" -l skip-std-check-if-no-download-rustc -d 'Skip checking the standard library if `rust.download-rustc` isn\'t available. This is mostly for RA as building the stage1 compiler to check the library tree on each code change might be too much for some computers'
 complete -c x -n "__fish_x_using_subcommand setup" -s h -l help -d 'Print help (see more with \'--help\')'
-complete -c x -n "__fish_x_using_subcommand suggest" -l config -d 'TOML configuration file for build' -r -F
-complete -c x -n "__fish_x_using_subcommand suggest" -l build-dir -d 'Build directory, overrides `build.build-dir` in `bootstrap.toml`' -r -f -a "(__fish_complete_directories)"
-complete -c x -n "__fish_x_using_subcommand suggest" -l build -d 'host target of the stage0 compiler' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l host -d 'host targets to build' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l target -d 'target targets to build' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l exclude -d 'build paths to exclude' -r -F
-complete -c x -n "__fish_x_using_subcommand suggest" -l skip -d 'build paths to skip' -r -F
-complete -c x -n "__fish_x_using_subcommand suggest" -l rustc-error-format -d 'rustc error format' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l on-fail -d 'command to run on failure' -r -f -a "(__fish_complete_command)"
-complete -c x -n "__fish_x_using_subcommand suggest" -l stage -d 'stage to build (indicates compiler to use/test, e.g., stage 0 uses the bootstrap compiler, stage 1 the stage 0 rustc artifacts, etc.)' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l keep-stage -d 'stage(s) to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l keep-stage-std -d 'stage(s) of the standard library to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l src -d 'path to the root of the rust checkout' -r -f -a "(__fish_complete_directories)"
-complete -c x -n "__fish_x_using_subcommand suggest" -s j -l jobs -d 'number of jobs to run in parallel' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l warnings -d 'if value is deny, will deny warnings if value is warn, will emit warnings otherwise, use the default configured behaviour' -r -f -a "{deny\t'',warn\t'',default\t''}"
-complete -c x -n "__fish_x_using_subcommand suggest" -l color -d 'whether to use color in cargo and rustc output' -r -f -a "{always\t'',never\t'',auto\t''}"
-complete -c x -n "__fish_x_using_subcommand suggest" -l rust-profile-generate -d 'generate PGO profile with rustc build' -r -F
-complete -c x -n "__fish_x_using_subcommand suggest" -l rust-profile-use -d 'use PGO profile for rustc build' -r -F
-complete -c x -n "__fish_x_using_subcommand suggest" -l llvm-profile-use -d 'use PGO profile for LLVM build' -r -F
-complete -c x -n "__fish_x_using_subcommand suggest" -l reproducible-artifact -d 'Additional reproducible artifacts that should be added to the reproducible artifacts archive' -r
-complete -c x -n "__fish_x_using_subcommand suggest" -l set -d 'override options in bootstrap.toml' -r -f
-complete -c x -n "__fish_x_using_subcommand suggest" -l ci -d 'Make bootstrap to behave as it\'s running on the CI environment or not' -r -f -a "{true\t'',false\t''}"
-complete -c x -n "__fish_x_using_subcommand suggest" -l run -d 'run suggested tests'
-complete -c x -n "__fish_x_using_subcommand suggest" -s v -l verbose -d 'use verbose output (-vv for very verbose)'
-complete -c x -n "__fish_x_using_subcommand suggest" -s i -l incremental -d 'use incremental compilation'
-complete -c x -n "__fish_x_using_subcommand suggest" -l include-default-paths -d 'include default paths in addition to the provided ones'
-complete -c x -n "__fish_x_using_subcommand suggest" -l dry-run -d 'dry run; don\'t build anything'
-complete -c x -n "__fish_x_using_subcommand suggest" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
-complete -c x -n "__fish_x_using_subcommand suggest" -l json-output -d 'use message-format=json'
-complete -c x -n "__fish_x_using_subcommand suggest" -l compile-time-deps -d 'only build proc-macros and build scripts (for rust-analyzer)'
-complete -c x -n "__fish_x_using_subcommand suggest" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
-complete -c x -n "__fish_x_using_subcommand suggest" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
-complete -c x -n "__fish_x_using_subcommand suggest" -l enable-bolt-settings -d 'Enable BOLT link flags'
-complete -c x -n "__fish_x_using_subcommand suggest" -l skip-stage0-validation -d 'Skip stage0 compiler validation'
-complete -c x -n "__fish_x_using_subcommand suggest" -l skip-std-check-if-no-download-rustc -d 'Skip checking the standard library if `rust.download-rustc` isn\'t available. This is mostly for RA as building the stage1 compiler to check the library tree on each code change might be too much for some computers'
-complete -c x -n "__fish_x_using_subcommand suggest" -s h -l help -d 'Print help (see more with \'--help\')'
 complete -c x -n "__fish_x_using_subcommand vendor" -l sync -d 'Additional `Cargo.toml` to sync and vendor' -r -F
 complete -c x -n "__fish_x_using_subcommand vendor" -l config -d 'TOML configuration file for build' -r -F
 complete -c x -n "__fish_x_using_subcommand vendor" -l build-dir -d 'Build directory, overrides `build.build-dir` in `bootstrap.toml`' -r -f -a "(__fish_complete_directories)"
diff --git a/src/etc/completions/x.ps1 b/src/etc/completions/x.ps1
index b5b59c58bba..0c9b3828273 100644
--- a/src/etc/completions/x.ps1
+++ b/src/etc/completions/x.ps1
@@ -74,7 +74,6 @@ Register-ArgumentCompleter -Native -CommandName 'x' -ScriptBlock {
             [CompletionResult]::new('install', 'install', [CompletionResultType]::ParameterValue, 'Install distribution artifacts')
             [CompletionResult]::new('run', 'run', [CompletionResultType]::ParameterValue, 'Run tools contained in this repository')
             [CompletionResult]::new('setup', 'setup', [CompletionResultType]::ParameterValue, 'Set up the environment for development')
-            [CompletionResult]::new('suggest', 'suggest', [CompletionResultType]::ParameterValue, 'Suggest a subset of tests to run, based on modified files')
             [CompletionResult]::new('vendor', 'vendor', [CompletionResultType]::ParameterValue, 'Vendor dependencies')
             [CompletionResult]::new('perf', 'perf', [CompletionResultType]::ParameterValue, 'Perform profiling and benchmarking of the compiler using `rustc-perf`')
             break
@@ -700,49 +699,6 @@ Register-ArgumentCompleter -Native -CommandName 'x' -ScriptBlock {
             [CompletionResult]::new('--help', '--help', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
             break
         }
-        'x;suggest' {
-            [CompletionResult]::new('--config', '--config', [CompletionResultType]::ParameterName, 'TOML configuration file for build')
-            [CompletionResult]::new('--build-dir', '--build-dir', [CompletionResultType]::ParameterName, 'Build directory, overrides `build.build-dir` in `bootstrap.toml`')
-            [CompletionResult]::new('--build', '--build', [CompletionResultType]::ParameterName, 'host target of the stage0 compiler')
-            [CompletionResult]::new('--host', '--host', [CompletionResultType]::ParameterName, 'host targets to build')
-            [CompletionResult]::new('--target', '--target', [CompletionResultType]::ParameterName, 'target targets to build')
-            [CompletionResult]::new('--exclude', '--exclude', [CompletionResultType]::ParameterName, 'build paths to exclude')
-            [CompletionResult]::new('--skip', '--skip', [CompletionResultType]::ParameterName, 'build paths to skip')
-            [CompletionResult]::new('--rustc-error-format', '--rustc-error-format', [CompletionResultType]::ParameterName, 'rustc error format')
-            [CompletionResult]::new('--on-fail', '--on-fail', [CompletionResultType]::ParameterName, 'command to run on failure')
-            [CompletionResult]::new('--stage', '--stage', [CompletionResultType]::ParameterName, 'stage to build (indicates compiler to use/test, e.g., stage 0 uses the bootstrap compiler, stage 1 the stage 0 rustc artifacts, etc.)')
-            [CompletionResult]::new('--keep-stage', '--keep-stage', [CompletionResultType]::ParameterName, 'stage(s) to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)')
-            [CompletionResult]::new('--keep-stage-std', '--keep-stage-std', [CompletionResultType]::ParameterName, 'stage(s) of the standard library to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)')
-            [CompletionResult]::new('--src', '--src', [CompletionResultType]::ParameterName, 'path to the root of the rust checkout')
-            [CompletionResult]::new('-j', '-j', [CompletionResultType]::ParameterName, 'number of jobs to run in parallel')
-            [CompletionResult]::new('--jobs', '--jobs', [CompletionResultType]::ParameterName, 'number of jobs to run in parallel')
-            [CompletionResult]::new('--warnings', '--warnings', [CompletionResultType]::ParameterName, 'if value is deny, will deny warnings if value is warn, will emit warnings otherwise, use the default configured behaviour')
-            [CompletionResult]::new('--color', '--color', [CompletionResultType]::ParameterName, 'whether to use color in cargo and rustc output')
-            [CompletionResult]::new('--rust-profile-generate', '--rust-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with rustc build')
-            [CompletionResult]::new('--rust-profile-use', '--rust-profile-use', [CompletionResultType]::ParameterName, 'use PGO profile for rustc build')
-            [CompletionResult]::new('--llvm-profile-use', '--llvm-profile-use', [CompletionResultType]::ParameterName, 'use PGO profile for LLVM build')
-            [CompletionResult]::new('--reproducible-artifact', '--reproducible-artifact', [CompletionResultType]::ParameterName, 'Additional reproducible artifacts that should be added to the reproducible artifacts archive')
-            [CompletionResult]::new('--set', '--set', [CompletionResultType]::ParameterName, 'override options in bootstrap.toml')
-            [CompletionResult]::new('--ci', '--ci', [CompletionResultType]::ParameterName, 'Make bootstrap to behave as it''s running on the CI environment or not')
-            [CompletionResult]::new('--run', '--run', [CompletionResultType]::ParameterName, 'run suggested tests')
-            [CompletionResult]::new('-v', '-v', [CompletionResultType]::ParameterName, 'use verbose output (-vv for very verbose)')
-            [CompletionResult]::new('--verbose', '--verbose', [CompletionResultType]::ParameterName, 'use verbose output (-vv for very verbose)')
-            [CompletionResult]::new('-i', '-i', [CompletionResultType]::ParameterName, 'use incremental compilation')
-            [CompletionResult]::new('--incremental', '--incremental', [CompletionResultType]::ParameterName, 'use incremental compilation')
-            [CompletionResult]::new('--include-default-paths', '--include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
-            [CompletionResult]::new('--dry-run', '--dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
-            [CompletionResult]::new('--dump-bootstrap-shims', '--dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
-            [CompletionResult]::new('--json-output', '--json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
-            [CompletionResult]::new('--compile-time-deps', '--compile-time-deps', [CompletionResultType]::ParameterName, 'only build proc-macros and build scripts (for rust-analyzer)')
-            [CompletionResult]::new('--bypass-bootstrap-lock', '--bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
-            [CompletionResult]::new('--llvm-profile-generate', '--llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
-            [CompletionResult]::new('--enable-bolt-settings', '--enable-bolt-settings', [CompletionResultType]::ParameterName, 'Enable BOLT link flags')
-            [CompletionResult]::new('--skip-stage0-validation', '--skip-stage0-validation', [CompletionResultType]::ParameterName, 'Skip stage0 compiler validation')
-            [CompletionResult]::new('--skip-std-check-if-no-download-rustc', '--skip-std-check-if-no-download-rustc', [CompletionResultType]::ParameterName, 'Skip checking the standard library if `rust.download-rustc` isn''t available. This is mostly for RA as building the stage1 compiler to check the library tree on each code change might be too much for some computers')
-            [CompletionResult]::new('-h', '-h', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
-            [CompletionResult]::new('--help', '--help', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
-            break
-        }
         'x;vendor' {
             [CompletionResult]::new('--sync', '--sync', [CompletionResultType]::ParameterName, 'Additional `Cargo.toml` to sync and vendor')
             [CompletionResult]::new('--config', '--config', [CompletionResultType]::ParameterName, 'TOML configuration file for build')
diff --git a/src/etc/completions/x.py.fish b/src/etc/completions/x.py.fish
index da7680a879d..43ae7424e27 100644
--- a/src/etc/completions/x.py.fish
+++ b/src/etc/completions/x.py.fish
@@ -73,7 +73,6 @@ complete -c x.py -n "__fish_x.py_needs_command" -a "dist" -d 'Build distribution
 complete -c x.py -n "__fish_x.py_needs_command" -a "install" -d 'Install distribution artifacts'
 complete -c x.py -n "__fish_x.py_needs_command" -a "run" -d 'Run tools contained in this repository'
 complete -c x.py -n "__fish_x.py_needs_command" -a "setup" -d 'Set up the environment for development'
-complete -c x.py -n "__fish_x.py_needs_command" -a "suggest" -d 'Suggest a subset of tests to run, based on modified files'
 complete -c x.py -n "__fish_x.py_needs_command" -a "vendor" -d 'Vendor dependencies'
 complete -c x.py -n "__fish_x.py_needs_command" -a "perf" -d 'Perform profiling and benchmarking of the compiler using `rustc-perf`'
 complete -c x.py -n "__fish_x.py_using_subcommand build" -l config -d 'TOML configuration file for build' -r -F
@@ -599,42 +598,6 @@ complete -c x.py -n "__fish_x.py_using_subcommand setup" -l enable-bolt-settings
 complete -c x.py -n "__fish_x.py_using_subcommand setup" -l skip-stage0-validation -d 'Skip stage0 compiler validation'
 complete -c x.py -n "__fish_x.py_using_subcommand setup" -l skip-std-check-if-no-download-rustc -d 'Skip checking the standard library if `rust.download-rustc` isn\'t available. This is mostly for RA as building the stage1 compiler to check the library tree on each code change might be too much for some computers'
 complete -c x.py -n "__fish_x.py_using_subcommand setup" -s h -l help -d 'Print help (see more with \'--help\')'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l config -d 'TOML configuration file for build' -r -F
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l build-dir -d 'Build directory, overrides `build.build-dir` in `bootstrap.toml`' -r -f -a "(__fish_complete_directories)"
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l build -d 'host target of the stage0 compiler' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l host -d 'host targets to build' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l target -d 'target targets to build' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l exclude -d 'build paths to exclude' -r -F
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l skip -d 'build paths to skip' -r -F
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l rustc-error-format -d 'rustc error format' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l on-fail -d 'command to run on failure' -r -f -a "(__fish_complete_command)"
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l stage -d 'stage to build (indicates compiler to use/test, e.g., stage 0 uses the bootstrap compiler, stage 1 the stage 0 rustc artifacts, etc.)' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l keep-stage -d 'stage(s) to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l keep-stage-std -d 'stage(s) of the standard library to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l src -d 'path to the root of the rust checkout' -r -f -a "(__fish_complete_directories)"
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -s j -l jobs -d 'number of jobs to run in parallel' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l warnings -d 'if value is deny, will deny warnings if value is warn, will emit warnings otherwise, use the default configured behaviour' -r -f -a "{deny\t'',warn\t'',default\t''}"
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l color -d 'whether to use color in cargo and rustc output' -r -f -a "{always\t'',never\t'',auto\t''}"
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l rust-profile-generate -d 'generate PGO profile with rustc build' -r -F
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l rust-profile-use -d 'use PGO profile for rustc build' -r -F
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l llvm-profile-use -d 'use PGO profile for LLVM build' -r -F
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l reproducible-artifact -d 'Additional reproducible artifacts that should be added to the reproducible artifacts archive' -r
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l set -d 'override options in bootstrap.toml' -r -f
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l ci -d 'Make bootstrap to behave as it\'s running on the CI environment or not' -r -f -a "{true\t'',false\t''}"
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l run -d 'run suggested tests'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -s v -l verbose -d 'use verbose output (-vv for very verbose)'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -s i -l incremental -d 'use incremental compilation'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l include-default-paths -d 'include default paths in addition to the provided ones'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l dry-run -d 'dry run; don\'t build anything'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l json-output -d 'use message-format=json'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l compile-time-deps -d 'only build proc-macros and build scripts (for rust-analyzer)'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l enable-bolt-settings -d 'Enable BOLT link flags'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l skip-stage0-validation -d 'Skip stage0 compiler validation'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -l skip-std-check-if-no-download-rustc -d 'Skip checking the standard library if `rust.download-rustc` isn\'t available. This is mostly for RA as building the stage1 compiler to check the library tree on each code change might be too much for some computers'
-complete -c x.py -n "__fish_x.py_using_subcommand suggest" -s h -l help -d 'Print help (see more with \'--help\')'
 complete -c x.py -n "__fish_x.py_using_subcommand vendor" -l sync -d 'Additional `Cargo.toml` to sync and vendor' -r -F
 complete -c x.py -n "__fish_x.py_using_subcommand vendor" -l config -d 'TOML configuration file for build' -r -F
 complete -c x.py -n "__fish_x.py_using_subcommand vendor" -l build-dir -d 'Build directory, overrides `build.build-dir` in `bootstrap.toml`' -r -f -a "(__fish_complete_directories)"
diff --git a/src/etc/completions/x.py.ps1 b/src/etc/completions/x.py.ps1
index 3fc8e7d5bbd..4311e383d64 100644
--- a/src/etc/completions/x.py.ps1
+++ b/src/etc/completions/x.py.ps1
@@ -74,7 +74,6 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('install', 'install', [CompletionResultType]::ParameterValue, 'Install distribution artifacts')
             [CompletionResult]::new('run', 'run', [CompletionResultType]::ParameterValue, 'Run tools contained in this repository')
             [CompletionResult]::new('setup', 'setup', [CompletionResultType]::ParameterValue, 'Set up the environment for development')
-            [CompletionResult]::new('suggest', 'suggest', [CompletionResultType]::ParameterValue, 'Suggest a subset of tests to run, based on modified files')
             [CompletionResult]::new('vendor', 'vendor', [CompletionResultType]::ParameterValue, 'Vendor dependencies')
             [CompletionResult]::new('perf', 'perf', [CompletionResultType]::ParameterValue, 'Perform profiling and benchmarking of the compiler using `rustc-perf`')
             break
@@ -700,49 +699,6 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--help', '--help', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
             break
         }
-        'x.py;suggest' {
-            [CompletionResult]::new('--config', '--config', [CompletionResultType]::ParameterName, 'TOML configuration file for build')
-            [CompletionResult]::new('--build-dir', '--build-dir', [CompletionResultType]::ParameterName, 'Build directory, overrides `build.build-dir` in `bootstrap.toml`')
-            [CompletionResult]::new('--build', '--build', [CompletionResultType]::ParameterName, 'host target of the stage0 compiler')
-            [CompletionResult]::new('--host', '--host', [CompletionResultType]::ParameterName, 'host targets to build')
-            [CompletionResult]::new('--target', '--target', [CompletionResultType]::ParameterName, 'target targets to build')
-            [CompletionResult]::new('--exclude', '--exclude', [CompletionResultType]::ParameterName, 'build paths to exclude')
-            [CompletionResult]::new('--skip', '--skip', [CompletionResultType]::ParameterName, 'build paths to skip')
-            [CompletionResult]::new('--rustc-error-format', '--rustc-error-format', [CompletionResultType]::ParameterName, 'rustc error format')
-            [CompletionResult]::new('--on-fail', '--on-fail', [CompletionResultType]::ParameterName, 'command to run on failure')
-            [CompletionResult]::new('--stage', '--stage', [CompletionResultType]::ParameterName, 'stage to build (indicates compiler to use/test, e.g., stage 0 uses the bootstrap compiler, stage 1 the stage 0 rustc artifacts, etc.)')
-            [CompletionResult]::new('--keep-stage', '--keep-stage', [CompletionResultType]::ParameterName, 'stage(s) to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)')
-            [CompletionResult]::new('--keep-stage-std', '--keep-stage-std', [CompletionResultType]::ParameterName, 'stage(s) of the standard library to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)')
-            [CompletionResult]::new('--src', '--src', [CompletionResultType]::ParameterName, 'path to the root of the rust checkout')
-            [CompletionResult]::new('-j', '-j', [CompletionResultType]::ParameterName, 'number of jobs to run in parallel')
-            [CompletionResult]::new('--jobs', '--jobs', [CompletionResultType]::ParameterName, 'number of jobs to run in parallel')
-            [CompletionResult]::new('--warnings', '--warnings', [CompletionResultType]::ParameterName, 'if value is deny, will deny warnings if value is warn, will emit warnings otherwise, use the default configured behaviour')
-            [CompletionResult]::new('--color', '--color', [CompletionResultType]::ParameterName, 'whether to use color in cargo and rustc output')
-            [CompletionResult]::new('--rust-profile-generate', '--rust-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with rustc build')
-            [CompletionResult]::new('--rust-profile-use', '--rust-profile-use', [CompletionResultType]::ParameterName, 'use PGO profile for rustc build')
-            [CompletionResult]::new('--llvm-profile-use', '--llvm-profile-use', [CompletionResultType]::ParameterName, 'use PGO profile for LLVM build')
-            [CompletionResult]::new('--reproducible-artifact', '--reproducible-artifact', [CompletionResultType]::ParameterName, 'Additional reproducible artifacts that should be added to the reproducible artifacts archive')
-            [CompletionResult]::new('--set', '--set', [CompletionResultType]::ParameterName, 'override options in bootstrap.toml')
-            [CompletionResult]::new('--ci', '--ci', [CompletionResultType]::ParameterName, 'Make bootstrap to behave as it''s running on the CI environment or not')
-            [CompletionResult]::new('--run', '--run', [CompletionResultType]::ParameterName, 'run suggested tests')
-            [CompletionResult]::new('-v', '-v', [CompletionResultType]::ParameterName, 'use verbose output (-vv for very verbose)')
-            [CompletionResult]::new('--verbose', '--verbose', [CompletionResultType]::ParameterName, 'use verbose output (-vv for very verbose)')
-            [CompletionResult]::new('-i', '-i', [CompletionResultType]::ParameterName, 'use incremental compilation')
-            [CompletionResult]::new('--incremental', '--incremental', [CompletionResultType]::ParameterName, 'use incremental compilation')
-            [CompletionResult]::new('--include-default-paths', '--include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
-            [CompletionResult]::new('--dry-run', '--dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
-            [CompletionResult]::new('--dump-bootstrap-shims', '--dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
-            [CompletionResult]::new('--json-output', '--json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
-            [CompletionResult]::new('--compile-time-deps', '--compile-time-deps', [CompletionResultType]::ParameterName, 'only build proc-macros and build scripts (for rust-analyzer)')
-            [CompletionResult]::new('--bypass-bootstrap-lock', '--bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
-            [CompletionResult]::new('--llvm-profile-generate', '--llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
-            [CompletionResult]::new('--enable-bolt-settings', '--enable-bolt-settings', [CompletionResultType]::ParameterName, 'Enable BOLT link flags')
-            [CompletionResult]::new('--skip-stage0-validation', '--skip-stage0-validation', [CompletionResultType]::ParameterName, 'Skip stage0 compiler validation')
-            [CompletionResult]::new('--skip-std-check-if-no-download-rustc', '--skip-std-check-if-no-download-rustc', [CompletionResultType]::ParameterName, 'Skip checking the standard library if `rust.download-rustc` isn''t available. This is mostly for RA as building the stage1 compiler to check the library tree on each code change might be too much for some computers')
-            [CompletionResult]::new('-h', '-h', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
-            [CompletionResult]::new('--help', '--help', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
-            break
-        }
         'x.py;vendor' {
             [CompletionResult]::new('--sync', '--sync', [CompletionResultType]::ParameterName, 'Additional `Cargo.toml` to sync and vendor')
             [CompletionResult]::new('--config', '--config', [CompletionResultType]::ParameterName, 'TOML configuration file for build')
diff --git a/src/etc/completions/x.py.sh b/src/etc/completions/x.py.sh
index 8f13de282fb..f31bdb58dc4 100644
--- a/src/etc/completions/x.py.sh
+++ b/src/etc/completions/x.py.sh
@@ -54,9 +54,6 @@ _x.py() {
             x.py,setup)
                 cmd="x.py__setup"
                 ;;
-            x.py,suggest)
-                cmd="x.py__suggest"
-                ;;
             x.py,test)
                 cmd="x.py__test"
                 ;;
@@ -85,7 +82,7 @@ _x.py() {
 
     case "${cmd}" in
         x.py)
-            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --json-output --compile-time-deps --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --ci --skip-std-check-if-no-download-rustc --help [PATHS]... [ARGS]... build check clippy fix fmt doc test miri bench clean dist install run setup suggest vendor perf"
+            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --json-output --compile-time-deps --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --ci --skip-std-check-if-no-download-rustc --help [PATHS]... [ARGS]... build check clippy fix fmt doc test miri bench clean dist install run setup vendor perf"
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 1 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -3877,192 +3874,6 @@ _x.py() {
             COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
             return 0
             ;;
-        x.py__suggest)
-            opts="-v -i -j -h --run --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --json-output --compile-time-deps --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --ci --skip-std-check-if-no-download-rustc --help [PATHS]... [ARGS]..."
-            if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
-                COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
-                return 0
-            fi
-            case "${prev}" in
-                --config)
-                    local oldifs
-                    if [ -n "${IFS+x}" ]; then
-                        oldifs="$IFS"
-                    fi
-                    IFS=$'\n'
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    if [ -n "${oldifs+x}" ]; then
-                        IFS="$oldifs"
-                    fi
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o filenames
-                    fi
-                    return 0
-                    ;;
-                --build-dir)
-                    COMPREPLY=()
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o plusdirs
-                    fi
-                    return 0
-                    ;;
-                --build)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --host)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --target)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --exclude)
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    return 0
-                    ;;
-                --skip)
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    return 0
-                    ;;
-                --rustc-error-format)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --on-fail)
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    return 0
-                    ;;
-                --stage)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --keep-stage)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --keep-stage-std)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --src)
-                    COMPREPLY=()
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o plusdirs
-                    fi
-                    return 0
-                    ;;
-                --jobs)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                -j)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --warnings)
-                    COMPREPLY=($(compgen -W "deny warn default" -- "${cur}"))
-                    return 0
-                    ;;
-                --color)
-                    COMPREPLY=($(compgen -W "always never auto" -- "${cur}"))
-                    return 0
-                    ;;
-                --rust-profile-generate)
-                    local oldifs
-                    if [ -n "${IFS+x}" ]; then
-                        oldifs="$IFS"
-                    fi
-                    IFS=$'\n'
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    if [ -n "${oldifs+x}" ]; then
-                        IFS="$oldifs"
-                    fi
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o filenames
-                    fi
-                    return 0
-                    ;;
-                --rust-profile-use)
-                    local oldifs
-                    if [ -n "${IFS+x}" ]; then
-                        oldifs="$IFS"
-                    fi
-                    IFS=$'\n'
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    if [ -n "${oldifs+x}" ]; then
-                        IFS="$oldifs"
-                    fi
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o filenames
-                    fi
-                    return 0
-                    ;;
-                --llvm-profile-use)
-                    local oldifs
-                    if [ -n "${IFS+x}" ]; then
-                        oldifs="$IFS"
-                    fi
-                    IFS=$'\n'
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    if [ -n "${oldifs+x}" ]; then
-                        IFS="$oldifs"
-                    fi
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o filenames
-                    fi
-                    return 0
-                    ;;
-                --reproducible-artifact)
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    return 0
-                    ;;
-                --set)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --ci)
-                    COMPREPLY=($(compgen -W "true false" -- "${cur}"))
-                    return 0
-                    ;;
-                *)
-                    COMPREPLY=()
-                    ;;
-            esac
-            COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
-            return 0
-            ;;
         x.py__test)
             opts="-v -i -j -h --no-fail-fast --test-args --compiletest-rustc-args --no-doc --doc --bless --extra-checks --force-rerun --only-modified --compare-mode --pass --run --rustfix-coverage --no-capture --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --json-output --compile-time-deps --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --ci --skip-std-check-if-no-download-rustc --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
diff --git a/src/etc/completions/x.py.zsh b/src/etc/completions/x.py.zsh
index 60ce9002116..aff35b31e21 100644
--- a/src/etc/completions/x.py.zsh
+++ b/src/etc/completions/x.py.zsh
@@ -715,51 +715,6 @@ _arguments "${_arguments_options[@]}" : \
 '*::paths -- paths for the subcommand:_files' \
 && ret=0
 ;;
-(suggest)
-_arguments "${_arguments_options[@]}" : \
-'--config=[TOML configuration file for build]:FILE:_files' \
-'--build-dir=[Build directory, overrides \`build.build-dir\` in \`bootstrap.toml\`]:DIR:_files -/' \
-'--build=[host target of the stage0 compiler]:BUILD:' \
-'--host=[host targets to build]:HOST:' \
-'--target=[target targets to build]:TARGET:' \
-'*--exclude=[build paths to exclude]:PATH:_files' \
-'*--skip=[build paths to skip]:PATH:_files' \
-'--rustc-error-format=[rustc error format]:RUSTC_ERROR_FORMAT:' \
-'--on-fail=[command to run on failure]:CMD:_cmdstring' \
-'--stage=[stage to build (indicates compiler to use/test, e.g., stage 0 uses the bootstrap compiler, stage 1 the stage 0 rustc artifacts, etc.)]:N:' \
-'*--keep-stage=[stage(s) to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)]:N:' \
-'*--keep-stage-std=[stage(s) of the standard library to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)]:N:' \
-'--src=[path to the root of the rust checkout]:DIR:_files -/' \
-'-j+[number of jobs to run in parallel]:JOBS:' \
-'--jobs=[number of jobs to run in parallel]:JOBS:' \
-'--warnings=[if value is deny, will deny warnings if value is warn, will emit warnings otherwise, use the default configured behaviour]:deny|warn:(deny warn default)' \
-'--color=[whether to use color in cargo and rustc output]:STYLE:(always never auto)' \
-'--rust-profile-generate=[generate PGO profile with rustc build]:PROFILE:_files' \
-'--rust-profile-use=[use PGO profile for rustc build]:PROFILE:_files' \
-'--llvm-profile-use=[use PGO profile for LLVM build]:PROFILE:_files' \
-'*--reproducible-artifact=[Additional reproducible artifacts that should be added to the reproducible artifacts archive]:REPRODUCIBLE_ARTIFACT:_default' \
-'*--set=[override options in bootstrap.toml]:section.option=value:' \
-'--ci=[Make bootstrap to behave as it'\''s running on the CI environment or not]:bool:(true false)' \
-'--run[run suggested tests]' \
-'*-v[use verbose output (-vv for very verbose)]' \
-'*--verbose[use verbose output (-vv for very verbose)]' \
-'-i[use incremental compilation]' \
-'--incremental[use incremental compilation]' \
-'--include-default-paths[include default paths in addition to the provided ones]' \
-'--dry-run[dry run; don'\''t build anything]' \
-'--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
-'--json-output[use message-format=json]' \
-'--compile-time-deps[only build proc-macros and build scripts (for rust-analyzer)]' \
-'--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
-'--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
-'--enable-bolt-settings[Enable BOLT link flags]' \
-'--skip-stage0-validation[Skip stage0 compiler validation]' \
-'--skip-std-check-if-no-download-rustc[Skip checking the standard library if \`rust.download-rustc\` isn'\''t available. This is mostly for RA as building the stage1 compiler to check the library tree on each code change might be too much for some computers]' \
-'-h[Print help (see more with '\''--help'\'')]' \
-'--help[Print help (see more with '\''--help'\'')]' \
-'*::paths -- paths for the subcommand:_files' \
-&& ret=0
-;;
 (vendor)
 _arguments "${_arguments_options[@]}" : \
 '*--sync=[Additional \`Cargo.toml\` to sync and vendor]:SYNC:_files' \
@@ -1120,7 +1075,6 @@ _x.py_commands() {
 'install:Install distribution artifacts' \
 'run:Run tools contained in this repository' \
 'setup:Set up the environment for development' \
-'suggest:Suggest a subset of tests to run, based on modified files' \
 'vendor:Vendor dependencies' \
 'perf:Perform profiling and benchmarking of the compiler using \`rustc-perf\`' \
     )
@@ -1227,11 +1181,6 @@ _x.py__setup_commands() {
     local commands; commands=()
     _describe -t commands 'x.py setup commands' commands "$@"
 }
-(( $+functions[_x.py__suggest_commands] )) ||
-_x.py__suggest_commands() {
-    local commands; commands=()
-    _describe -t commands 'x.py suggest commands' commands "$@"
-}
 (( $+functions[_x.py__test_commands] )) ||
 _x.py__test_commands() {
     local commands; commands=()
diff --git a/src/etc/completions/x.sh b/src/etc/completions/x.sh
index f6ecf4cebf4..927d8f7661c 100644
--- a/src/etc/completions/x.sh
+++ b/src/etc/completions/x.sh
@@ -54,9 +54,6 @@ _x() {
             x,setup)
                 cmd="x__setup"
                 ;;
-            x,suggest)
-                cmd="x__suggest"
-                ;;
             x,test)
                 cmd="x__test"
                 ;;
@@ -85,7 +82,7 @@ _x() {
 
     case "${cmd}" in
         x)
-            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --json-output --compile-time-deps --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --ci --skip-std-check-if-no-download-rustc --help [PATHS]... [ARGS]... build check clippy fix fmt doc test miri bench clean dist install run setup suggest vendor perf"
+            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --json-output --compile-time-deps --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --ci --skip-std-check-if-no-download-rustc --help [PATHS]... [ARGS]... build check clippy fix fmt doc test miri bench clean dist install run setup vendor perf"
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 1 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -3877,192 +3874,6 @@ _x() {
             COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
             return 0
             ;;
-        x__suggest)
-            opts="-v -i -j -h --run --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --json-output --compile-time-deps --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --ci --skip-std-check-if-no-download-rustc --help [PATHS]... [ARGS]..."
-            if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
-                COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
-                return 0
-            fi
-            case "${prev}" in
-                --config)
-                    local oldifs
-                    if [ -n "${IFS+x}" ]; then
-                        oldifs="$IFS"
-                    fi
-                    IFS=$'\n'
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    if [ -n "${oldifs+x}" ]; then
-                        IFS="$oldifs"
-                    fi
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o filenames
-                    fi
-                    return 0
-                    ;;
-                --build-dir)
-                    COMPREPLY=()
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o plusdirs
-                    fi
-                    return 0
-                    ;;
-                --build)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --host)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --target)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --exclude)
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    return 0
-                    ;;
-                --skip)
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    return 0
-                    ;;
-                --rustc-error-format)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --on-fail)
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    return 0
-                    ;;
-                --stage)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --keep-stage)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --keep-stage-std)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --src)
-                    COMPREPLY=()
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o plusdirs
-                    fi
-                    return 0
-                    ;;
-                --jobs)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                -j)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --warnings)
-                    COMPREPLY=($(compgen -W "deny warn default" -- "${cur}"))
-                    return 0
-                    ;;
-                --color)
-                    COMPREPLY=($(compgen -W "always never auto" -- "${cur}"))
-                    return 0
-                    ;;
-                --rust-profile-generate)
-                    local oldifs
-                    if [ -n "${IFS+x}" ]; then
-                        oldifs="$IFS"
-                    fi
-                    IFS=$'\n'
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    if [ -n "${oldifs+x}" ]; then
-                        IFS="$oldifs"
-                    fi
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o filenames
-                    fi
-                    return 0
-                    ;;
-                --rust-profile-use)
-                    local oldifs
-                    if [ -n "${IFS+x}" ]; then
-                        oldifs="$IFS"
-                    fi
-                    IFS=$'\n'
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    if [ -n "${oldifs+x}" ]; then
-                        IFS="$oldifs"
-                    fi
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o filenames
-                    fi
-                    return 0
-                    ;;
-                --llvm-profile-use)
-                    local oldifs
-                    if [ -n "${IFS+x}" ]; then
-                        oldifs="$IFS"
-                    fi
-                    IFS=$'\n'
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    if [ -n "${oldifs+x}" ]; then
-                        IFS="$oldifs"
-                    fi
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o filenames
-                    fi
-                    return 0
-                    ;;
-                --reproducible-artifact)
-                    COMPREPLY=($(compgen -f "${cur}"))
-                    return 0
-                    ;;
-                --set)
-                    COMPREPLY=("${cur}")
-                    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
-                        compopt -o nospace
-                    fi
-                    return 0
-                    ;;
-                --ci)
-                    COMPREPLY=($(compgen -W "true false" -- "${cur}"))
-                    return 0
-                    ;;
-                *)
-                    COMPREPLY=()
-                    ;;
-            esac
-            COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
-            return 0
-            ;;
         x__test)
             opts="-v -i -j -h --no-fail-fast --test-args --compiletest-rustc-args --no-doc --doc --bless --extra-checks --force-rerun --only-modified --compare-mode --pass --run --rustfix-coverage --no-capture --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --json-output --compile-time-deps --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --ci --skip-std-check-if-no-download-rustc --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
diff --git a/src/etc/completions/x.zsh b/src/etc/completions/x.zsh
index 452a26fef07..28ad00f3a0d 100644
--- a/src/etc/completions/x.zsh
+++ b/src/etc/completions/x.zsh
@@ -715,51 +715,6 @@ _arguments "${_arguments_options[@]}" : \
 '*::paths -- paths for the subcommand:_files' \
 && ret=0
 ;;
-(suggest)
-_arguments "${_arguments_options[@]}" : \
-'--config=[TOML configuration file for build]:FILE:_files' \
-'--build-dir=[Build directory, overrides \`build.build-dir\` in \`bootstrap.toml\`]:DIR:_files -/' \
-'--build=[host target of the stage0 compiler]:BUILD:' \
-'--host=[host targets to build]:HOST:' \
-'--target=[target targets to build]:TARGET:' \
-'*--exclude=[build paths to exclude]:PATH:_files' \
-'*--skip=[build paths to skip]:PATH:_files' \
-'--rustc-error-format=[rustc error format]:RUSTC_ERROR_FORMAT:' \
-'--on-fail=[command to run on failure]:CMD:_cmdstring' \
-'--stage=[stage to build (indicates compiler to use/test, e.g., stage 0 uses the bootstrap compiler, stage 1 the stage 0 rustc artifacts, etc.)]:N:' \
-'*--keep-stage=[stage(s) to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)]:N:' \
-'*--keep-stage-std=[stage(s) of the standard library to keep without recompiling (pass multiple times to keep e.g., both stages 0 and 1)]:N:' \
-'--src=[path to the root of the rust checkout]:DIR:_files -/' \
-'-j+[number of jobs to run in parallel]:JOBS:' \
-'--jobs=[number of jobs to run in parallel]:JOBS:' \
-'--warnings=[if value is deny, will deny warnings if value is warn, will emit warnings otherwise, use the default configured behaviour]:deny|warn:(deny warn default)' \
-'--color=[whether to use color in cargo and rustc output]:STYLE:(always never auto)' \
-'--rust-profile-generate=[generate PGO profile with rustc build]:PROFILE:_files' \
-'--rust-profile-use=[use PGO profile for rustc build]:PROFILE:_files' \
-'--llvm-profile-use=[use PGO profile for LLVM build]:PROFILE:_files' \
-'*--reproducible-artifact=[Additional reproducible artifacts that should be added to the reproducible artifacts archive]:REPRODUCIBLE_ARTIFACT:_default' \
-'*--set=[override options in bootstrap.toml]:section.option=value:' \
-'--ci=[Make bootstrap to behave as it'\''s running on the CI environment or not]:bool:(true false)' \
-'--run[run suggested tests]' \
-'*-v[use verbose output (-vv for very verbose)]' \
-'*--verbose[use verbose output (-vv for very verbose)]' \
-'-i[use incremental compilation]' \
-'--incremental[use incremental compilation]' \
-'--include-default-paths[include default paths in addition to the provided ones]' \
-'--dry-run[dry run; don'\''t build anything]' \
-'--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
-'--json-output[use message-format=json]' \
-'--compile-time-deps[only build proc-macros and build scripts (for rust-analyzer)]' \
-'--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
-'--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
-'--enable-bolt-settings[Enable BOLT link flags]' \
-'--skip-stage0-validation[Skip stage0 compiler validation]' \
-'--skip-std-check-if-no-download-rustc[Skip checking the standard library if \`rust.download-rustc\` isn'\''t available. This is mostly for RA as building the stage1 compiler to check the library tree on each code change might be too much for some computers]' \
-'-h[Print help (see more with '\''--help'\'')]' \
-'--help[Print help (see more with '\''--help'\'')]' \
-'*::paths -- paths for the subcommand:_files' \
-&& ret=0
-;;
 (vendor)
 _arguments "${_arguments_options[@]}" : \
 '*--sync=[Additional \`Cargo.toml\` to sync and vendor]:SYNC:_files' \
@@ -1120,7 +1075,6 @@ _x_commands() {
 'install:Install distribution artifacts' \
 'run:Run tools contained in this repository' \
 'setup:Set up the environment for development' \
-'suggest:Suggest a subset of tests to run, based on modified files' \
 'vendor:Vendor dependencies' \
 'perf:Perform profiling and benchmarking of the compiler using \`rustc-perf\`' \
     )
@@ -1227,11 +1181,6 @@ _x__setup_commands() {
     local commands; commands=()
     _describe -t commands 'x setup commands' commands "$@"
 }
-(( $+functions[_x__suggest_commands] )) ||
-_x__suggest_commands() {
-    local commands; commands=()
-    _describe -t commands 'x suggest commands' commands "$@"
-}
 (( $+functions[_x__test_commands] )) ||
 _x__test_commands() {
     local commands; commands=()
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index e7a1f4d8397..1265a39d27b 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -390,7 +390,8 @@ pub(crate) fn clean_predicate<'tcx>(
         ty::ClauseKind::ConstEvaluatable(..)
         | ty::ClauseKind::WellFormed(..)
         | ty::ClauseKind::ConstArgHasType(..)
-        // FIXME(const_trait_impl): We can probably use this `HostEffect` pred to render `[const]`.
+        | ty::ClauseKind::UnstableFeature(..)
+        // FIXME(const_trait_impl): We can probably use this `HostEffect` pred to render `~const`.
         | ty::ClauseKind::HostEffect(_) => None,
     }
 }
@@ -2864,7 +2865,7 @@ fn clean_maybe_renamed_item<'tcx>(
             ItemKind::Fn { ref sig, generics, body: body_id, .. } => {
                 clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
             }
-            ItemKind::Trait(_, _, _, generics, bounds, item_ids) => {
+            ItemKind::Trait(_, _, _, _, generics, bounds, item_ids) => {
                 let items = item_ids
                     .iter()
                     .map(|&ti| clean_trait_item(cx.tcx.hir_trait_item(ti), cx))
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 3ecd41db2dd..5ac5da24299 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -648,7 +648,7 @@ impl Item {
             let sig = tcx.fn_sig(def_id).skip_binder();
             let constness = if tcx.is_const_fn(def_id) {
                 // rustc's `is_const_fn` returns `true` for associated functions that have an `impl const` parent
-                // or that have a `#[const_trait]` parent. Do not display those as `const` in rustdoc because we
+                // or that have a `const trait` parent. Do not display those as `const` in rustdoc because we
                 // won't be printing correct syntax plus the syntax is unstable.
                 match tcx.opt_associated_item(def_id) {
                     Some(ty::AssocItem {
@@ -759,79 +759,48 @@ impl Item {
         Some(tcx.visibility(def_id))
     }
 
-    fn attributes_without_repr(&self, tcx: TyCtxt<'_>, is_json: bool) -> Vec<String> {
-        const ALLOWED_ATTRIBUTES: &[Symbol] =
-            &[sym::export_name, sym::link_section, sym::no_mangle, sym::non_exhaustive];
+    /// Get a list of attributes excluding `#[repr]` to display.
+    ///
+    /// Only used by the HTML output-format.
+    fn attributes_without_repr(&self) -> Vec<String> {
         self.attrs
             .other_attrs
             .iter()
-            .filter_map(|attr| {
-                if let hir::Attribute::Parsed(AttributeKind::LinkSection { name, .. }) = attr {
+            .filter_map(|attr| match attr {
+                hir::Attribute::Parsed(AttributeKind::LinkSection { name, .. }) => {
                     Some(format!("#[link_section = \"{name}\"]"))
                 }
-                // NoMangle is special cased, as it appears in HTML output, and we want to show it in source form, not HIR printing.
-                // It is also used by cargo-semver-checks.
-                else if let hir::Attribute::Parsed(AttributeKind::NoMangle(..)) = attr {
+                hir::Attribute::Parsed(AttributeKind::NoMangle(..)) => {
                     Some("#[no_mangle]".to_string())
-                } else if let hir::Attribute::Parsed(AttributeKind::ExportName { name, .. }) = attr
-                {
+                }
+                hir::Attribute::Parsed(AttributeKind::ExportName { name, .. }) => {
                     Some(format!("#[export_name = \"{name}\"]"))
-                } else if let hir::Attribute::Parsed(AttributeKind::NonExhaustive(..)) = attr {
+                }
+                hir::Attribute::Parsed(AttributeKind::NonExhaustive(..)) => {
                     Some("#[non_exhaustive]".to_string())
-                } else if is_json {
-                    match attr {
-                        // rustdoc-json stores this in `Item::deprecation`, so we
-                        // don't want it it `Item::attrs`.
-                        hir::Attribute::Parsed(AttributeKind::Deprecation { .. }) => None,
-                        // We have separate pretty-printing logic for `#[repr(..)]` attributes.
-                        hir::Attribute::Parsed(AttributeKind::Repr { .. }) => None,
-                        // target_feature is special-cased because cargo-semver-checks uses it
-                        hir::Attribute::Parsed(AttributeKind::TargetFeature(features, _)) => {
-                            let mut output = String::new();
-                            for (i, (feature, _)) in features.iter().enumerate() {
-                                if i != 0 {
-                                    output.push_str(", ");
-                                }
-                                output.push_str(&format!("enable=\"{}\"", feature.as_str()));
-                            }
-                            Some(format!("#[target_feature({output})]"))
-                        }
-                        hir::Attribute::Parsed(AttributeKind::AutomaticallyDerived(..)) => {
-                            Some("#[automatically_derived]".to_string())
-                        }
-                        _ => Some({
-                            let mut s = rustc_hir_pretty::attribute_to_string(&tcx, attr);
-                            assert_eq!(s.pop(), Some('\n'));
-                            s
-                        }),
-                    }
-                } else {
-                    if !attr.has_any_name(ALLOWED_ATTRIBUTES) {
-                        return None;
-                    }
-                    Some(
-                        rustc_hir_pretty::attribute_to_string(&tcx, attr)
-                            .replace("\\\n", "")
-                            .replace('\n', "")
-                            .replace("  ", " "),
-                    )
                 }
+                _ => None,
             })
             .collect()
     }
 
-    pub(crate) fn attributes(&self, tcx: TyCtxt<'_>, cache: &Cache, is_json: bool) -> Vec<String> {
-        let mut attrs = self.attributes_without_repr(tcx, is_json);
+    /// Get a list of attributes to display on this item.
+    ///
+    /// Only used by the HTML output-format.
+    pub(crate) fn attributes(&self, tcx: TyCtxt<'_>, cache: &Cache) -> Vec<String> {
+        let mut attrs = self.attributes_without_repr();
 
-        if let Some(repr_attr) = self.repr(tcx, cache, is_json) {
+        if let Some(repr_attr) = self.repr(tcx, cache) {
             attrs.push(repr_attr);
         }
         attrs
     }
 
     /// Returns a stringified `#[repr(...)]` attribute.
-    pub(crate) fn repr(&self, tcx: TyCtxt<'_>, cache: &Cache, is_json: bool) -> Option<String> {
-        repr_attributes(tcx, cache, self.def_id()?, self.type_(), is_json)
+    ///
+    /// Only used by the HTML output-format.
+    pub(crate) fn repr(&self, tcx: TyCtxt<'_>, cache: &Cache) -> Option<String> {
+        repr_attributes(tcx, cache, self.def_id()?, self.type_())
     }
 
     pub fn is_doc_hidden(&self) -> bool {
@@ -843,12 +812,14 @@ impl Item {
     }
 }
 
+/// Return a string representing the `#[repr]` attribute if present.
+///
+/// Only used by the HTML output-format.
 pub(crate) fn repr_attributes(
     tcx: TyCtxt<'_>,
     cache: &Cache,
     def_id: DefId,
     item_type: ItemType,
-    is_json: bool,
 ) -> Option<String> {
     use rustc_abi::IntegerType;
 
@@ -865,7 +836,6 @@ pub(crate) fn repr_attributes(
         // Render `repr(transparent)` iff the non-1-ZST field is public or at least one
         // field is public in case all fields are 1-ZST fields.
         let render_transparent = cache.document_private
-            || is_json
             || adt
                 .all_fields()
                 .find(|field| {
@@ -1707,7 +1677,7 @@ impl Type {
         }
     }
 
-    pub(crate) fn generics<'a>(&'a self) -> Option<impl Iterator<Item = &'a Type>> {
+    pub(crate) fn generics(&self) -> Option<impl Iterator<Item = &Type>> {
         match self {
             Type::Path { path, .. } => path.generics(),
             _ => None,
@@ -2257,7 +2227,7 @@ impl Path {
         self.segments.last().map(|seg| &seg.args)
     }
 
-    pub(crate) fn generics<'a>(&'a self) -> Option<impl Iterator<Item = &'a Type>> {
+    pub(crate) fn generics(&self) -> Option<impl Iterator<Item = &Type>> {
         self.segments.last().and_then(|seg| {
             if let GenericArgs::AngleBracketed { ref args, .. } = seg.args {
                 Some(args.iter().filter_map(|arg| match arg {
diff --git a/src/librustdoc/clean/utils.rs b/src/librustdoc/clean/utils.rs
index bf3f7607274..813fdee57e1 100644
--- a/src/librustdoc/clean/utils.rs
+++ b/src/librustdoc/clean/utils.rs
@@ -3,6 +3,7 @@ use std::fmt::{self, Display, Write as _};
 use std::sync::LazyLock as Lazy;
 use std::{ascii, mem};
 
+use rustc_ast::join_path_idents;
 use rustc_ast::tokenstream::TokenTree;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
@@ -24,7 +25,7 @@ use crate::clean::{
     clean_middle_ty, inline,
 };
 use crate::core::DocContext;
-use crate::display::{Joined as _, MaybeDisplay as _};
+use crate::display::Joined as _;
 
 #[cfg(test)]
 mod tests;
@@ -251,13 +252,7 @@ pub(crate) fn qpath_to_string(p: &hir::QPath<'_>) -> String {
         hir::QPath::LangItem(lang_item, ..) => return lang_item.name().to_string(),
     };
 
-    fmt::from_fn(|f| {
-        segments
-            .iter()
-            .map(|seg| (seg.ident.name != kw::PathRoot).then_some(seg.ident).maybe_display())
-            .joined("::", f)
-    })
-    .to_string()
+    join_path_idents(segments.iter().map(|seg| seg.ident))
 }
 
 pub(crate) fn build_deref_target_impls(
@@ -348,13 +343,11 @@ pub(crate) fn name_from_pat(p: &hir::Pat<'_>) -> Symbol {
 pub(crate) fn print_const(cx: &DocContext<'_>, n: ty::Const<'_>) -> String {
     match n.kind() {
         ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, args: _ }) => {
-            let s = if let Some(def) = def.as_local() {
+            if let Some(def) = def.as_local() {
                 rendered_const(cx.tcx, cx.tcx.hir_body_owned_by(def), def)
             } else {
                 inline::print_inlined_const(cx.tcx, def)
-            };
-
-            s
+            }
         }
         // array lengths are obviously usize
         ty::ConstKind::Value(cv) if *cv.ty.kind() == ty::Uint(ty::UintTy::Usize) => {
diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
index 9b4d2533954..38ba6b4503d 100644
--- a/src/librustdoc/doctest.rs
+++ b/src/librustdoc/doctest.rs
@@ -632,7 +632,7 @@ fn run_test(
         // the user to exploit nightly-only features on stable
         runner_compiler.env("RUSTC_BOOTSTRAP", "1");
         runner_compiler.args(compiler_args);
-        runner_compiler.args(&["--crate-type=bin", "-o"]).arg(&output_file);
+        runner_compiler.args(["--crate-type=bin", "-o"]).arg(&output_file);
         let mut extern_path = std::ffi::OsString::from(format!(
             "--extern=doctest_bundle_{edition}=",
             edition = doctest.edition
@@ -657,7 +657,7 @@ fn run_test(
         extern_path.push(&output_bundle_file);
         runner_compiler.arg(extern_path);
         runner_compiler.arg(&runner_input_file);
-        if std::fs::write(&runner_input_file, &merged_test_code).is_err() {
+        if std::fs::write(&runner_input_file, merged_test_code).is_err() {
             // If we cannot write this file for any reason, we leave. All combined tests will be
             // tested as standalone tests.
             return Err(TestFailure::CompileError);
diff --git a/src/librustdoc/doctest/rust.rs b/src/librustdoc/doctest/rust.rs
index 96975105ac5..f5ec828187a 100644
--- a/src/librustdoc/doctest/rust.rs
+++ b/src/librustdoc/doctest/rust.rs
@@ -140,7 +140,7 @@ impl HirCollector<'_> {
                 .iter()
                 .filter(|a| a.has_name(sym::attr))
                 .flat_map(|a| a.meta_item_list().unwrap_or_default())
-                .map(|i| pprust::meta_list_item_to_string(i))
+                .map(pprust::meta_list_item_to_string)
             {
                 // Add the additional attributes to the global_crate_attrs vector
                 self.collector.global_crate_attrs.push(attr);
diff --git a/src/librustdoc/formats/cache.rs b/src/librustdoc/formats/cache.rs
index 4989bd718c9..5191120ebdb 100644
--- a/src/librustdoc/formats/cache.rs
+++ b/src/librustdoc/formats/cache.rs
@@ -1,5 +1,6 @@
 use std::mem;
 
+use rustc_ast::join_path_syms;
 use rustc_attr_data_structures::StabilityLevel;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIdSet};
@@ -13,7 +14,6 @@ use crate::core::DocContext;
 use crate::fold::DocFolder;
 use crate::formats::Impl;
 use crate::formats::item_type::ItemType;
-use crate::html::format::join_with_double_colon;
 use crate::html::markdown::short_markdown_summary;
 use crate::html::render::IndexItem;
 use crate::html::render::search_index::get_function_type_for_search;
@@ -558,7 +558,7 @@ fn add_item_to_search_index(tcx: TyCtxt<'_>, cache: &mut Cache, item: &clean::It
         clean::ItemKind::ImportItem(import) => import.source.did.unwrap_or(item_def_id),
         _ => item_def_id,
     };
-    let path = join_with_double_colon(parent_path);
+    let path = join_path_syms(parent_path);
     let impl_id = if let Some(ParentStackItem::Impl { item_id, .. }) = cache.parent_stack.last() {
         item_id.as_def_id()
     } else {
diff --git a/src/librustdoc/formats/renderer.rs b/src/librustdoc/formats/renderer.rs
index 79ff1fa38c3..aa4be4db997 100644
--- a/src/librustdoc/formats/renderer.rs
+++ b/src/librustdoc/formats/renderer.rs
@@ -81,7 +81,7 @@ fn run_format_inner<'tcx, T: FormatRenderer<'tcx>>(
         let _timer =
             prof.generic_activity_with_arg("render_mod_item", item.name.unwrap().to_string());
 
-        cx.mod_item_in(&item)?;
+        cx.mod_item_in(item)?;
         let (clean::StrippedItem(box clean::ModuleItem(ref module))
         | clean::ModuleItem(ref module)) = item.inner.kind
         else {
@@ -99,7 +99,7 @@ fn run_format_inner<'tcx, T: FormatRenderer<'tcx>>(
     } else if let Some(item_name) = item.name
         && !item.is_extern_crate()
     {
-        prof.generic_activity_with_arg("render_item", item_name.as_str()).run(|| cx.item(&item))?;
+        prof.generic_activity_with_arg("render_item", item_name.as_str()).run(|| cx.item(item))?;
     }
     Ok(())
 }
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index bcb3e57c844..be8a2d511e9 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -14,6 +14,7 @@ use std::slice;
 
 use itertools::{Either, Itertools};
 use rustc_abi::ExternAbi;
+use rustc_ast::join_path_syms;
 use rustc_attr_data_structures::{ConstStability, StabilityLevel, StableSince};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
@@ -25,7 +26,7 @@ use rustc_span::symbol::kw;
 use rustc_span::{Symbol, sym};
 use tracing::{debug, trace};
 
-use super::url_parts_builder::{UrlPartsBuilder, estimate_item_path_byte_length};
+use super::url_parts_builder::UrlPartsBuilder;
 use crate::clean::types::ExternalLocation;
 use crate::clean::utils::find_nearest_parent_module;
 use crate::clean::{self, ExternalCrate, PrimitiveType};
@@ -113,9 +114,9 @@ impl clean::Generics {
             let real_params =
                 fmt::from_fn(|f| real_params.clone().map(|g| g.print(cx)).joined(", ", f));
             if f.alternate() {
-                write!(f, "<{:#}>", real_params)
+                write!(f, "<{real_params:#}>")
             } else {
-                write!(f, "&lt;{}&gt;", real_params)
+                write!(f, "&lt;{real_params}&gt;")
             }
         })
     }
@@ -369,18 +370,6 @@ pub(crate) enum HrefError {
     NotInExternalCache,
 }
 
-// Panics if `syms` is empty.
-pub(crate) fn join_with_double_colon(syms: &[Symbol]) -> String {
-    let mut s = String::with_capacity(estimate_item_path_byte_length(syms.len()));
-    // NOTE: using `Joined::joined` here causes a noticeable perf regression
-    s.push_str(syms[0].as_str());
-    for sym in &syms[1..] {
-        s.push_str("::");
-        s.push_str(sym.as_str());
-    }
-    s
-}
-
 /// This function is to get the external macro path because they are not in the cache used in
 /// `href_with_root_path`.
 fn generate_macro_def_id_path(
@@ -605,7 +594,7 @@ pub(crate) fn href_with_root_path(
             }
         }
     };
-    let url_parts = make_href(root_path, shortty, url_parts, &fqp, is_remote);
+    let url_parts = make_href(root_path, shortty, url_parts, fqp, is_remote);
     Ok((url_parts, shortty, fqp.clone()))
 }
 
@@ -672,7 +661,7 @@ pub(crate) fn link_tooltip(
             write!(f, "{}", cx.tcx().item_name(id))?;
         } else if !fqp.is_empty() {
             write!(f, "{shortty} ")?;
-            fqp.iter().joined("::", f)?;
+            write!(f, "{}", join_path_syms(fqp))?;
         }
         Ok(())
     })
@@ -703,7 +692,7 @@ fn resolved_path(
                     write!(
                         f,
                         "{path}::{anchor}",
-                        path = join_with_double_colon(&fqp[..fqp.len() - 1]),
+                        path = join_path_syms(&fqp[..fqp.len() - 1]),
                         anchor = print_anchor(did, *fqp.last().unwrap(), cx)
                     )
                 } else {
@@ -835,7 +824,7 @@ pub(crate) fn print_anchor(did: DefId, text: Symbol, cx: &Context<'_>) -> impl D
             write!(
                 f,
                 r#"<a class="{short_ty}" href="{url}" title="{short_ty} {path}">{text}</a>"#,
-                path = join_with_double_colon(&fqp),
+                path = join_path_syms(fqp),
                 text = EscapeBodyText(text.as_str()),
             )
         } else {
@@ -1095,7 +1084,7 @@ impl clean::QPathData {
                                     title=\"type {path}::{name}\">{name}</a>",
                         shortty = ItemType::AssocType,
                         name = assoc.name,
-                        path = join_with_double_colon(&path),
+                        path = join_path_syms(path),
                     )
                 } else {
                     write!(f, "{}", assoc.name)
@@ -1126,7 +1115,7 @@ impl clean::Impl {
                 {
                     let last = ty.last();
                     if f.alternate() {
-                        write!(f, "{}<", last)?;
+                        write!(f, "{last}<")?;
                         self.print_type(inner_type, f, use_absolute, cx)?;
                         write!(f, ">")?;
                     } else {
@@ -1230,7 +1219,7 @@ pub(crate) fn print_params(params: &[clean::Parameter], cx: &Context<'_>) -> imp
             .map(|param| {
                 fmt::from_fn(|f| {
                     if let Some(name) = param.name {
-                        write!(f, "{}: ", name)?;
+                        write!(f, "{name}: ")?;
                     }
                     param.type_.print(cx).fmt(f)
                 })
@@ -1352,7 +1341,7 @@ impl clean::FnDecl {
                     write!(f, "const ")?;
                 }
                 if let Some(name) = param.name {
-                    write!(f, "{}: ", name)?;
+                    write!(f, "{name}: ")?;
                 }
                 param.type_.print(cx).fmt(f)?;
             }
diff --git a/src/librustdoc/html/highlight.rs b/src/librustdoc/html/highlight.rs
index b2feee36c93..272180fb990 100644
--- a/src/librustdoc/html/highlight.rs
+++ b/src/librustdoc/html/highlight.rs
@@ -547,7 +547,7 @@ impl<'a> Iterator for TokenIter<'a> {
 fn get_real_ident_class(text: &str, allow_path_keywords: bool) -> Option<Class> {
     let ignore: &[&str] =
         if allow_path_keywords { &["self", "Self", "super", "crate"] } else { &["self", "Self"] };
-    if ignore.iter().any(|k| *k == text) {
+    if ignore.contains(&text) {
         return None;
     }
     Some(match text {
@@ -1159,7 +1159,7 @@ fn string_without_closing_tag<T: Display>(
         return Some("</a>");
     }
     if !open_tag {
-        write!(out, "{}", text_s).unwrap();
+        out.write_str(&text_s).unwrap();
         return None;
     }
     let klass_s = klass.as_html();
diff --git a/src/librustdoc/html/layout.rs b/src/librustdoc/html/layout.rs
index 50320cb231d..1f92c521d46 100644
--- a/src/librustdoc/html/layout.rs
+++ b/src/librustdoc/html/layout.rs
@@ -132,6 +132,5 @@ pub(crate) fn redirect(url: &str) -> String {
     <script>location.replace("{url}" + location.search + location.hash);</script>
 </body>
 </html>"##,
-        url = url,
     )
 }
diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index e41435de29c..4addf2c3c96 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -251,7 +251,7 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'_, 'a, I> {
                     if !parse_result.rust {
                         let added_classes = parse_result.added_classes;
                         let lang_string = if let Some(lang) = parse_result.unknown.first() {
-                            format!("language-{}", lang)
+                            format!("language-{lang}")
                         } else {
                             String::new()
                         };
@@ -999,7 +999,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
 
         if let Some((_, c)) = self.inner.next() {
             if c != '=' {
-                self.emit_error(format!("expected `=`, found `{}`", c));
+                self.emit_error(format!("expected `=`, found `{c}`"));
                 return None;
             }
         } else {
diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index 3b4dae841ee..5ceb1fc988d 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -6,6 +6,7 @@ use std::path::{Path, PathBuf};
 use std::sync::mpsc::{Receiver, channel};
 
 use askama::Template;
+use rustc_ast::join_path_syms;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_hir::def_id::{DefIdMap, LOCAL_CRATE};
 use rustc_middle::ty::TyCtxt;
@@ -27,7 +28,6 @@ use crate::formats::FormatRenderer;
 use crate::formats::cache::Cache;
 use crate::formats::item_type::ItemType;
 use crate::html::escape::Escape;
-use crate::html::format::join_with_double_colon;
 use crate::html::markdown::{self, ErrorCodes, IdMap, plain_text_summary};
 use crate::html::render::write_shared::write_shared;
 use crate::html::url_parts_builder::UrlPartsBuilder;
@@ -193,14 +193,12 @@ impl<'tcx> Context<'tcx> {
         if it.is_stripped()
             && let Some(def_id) = it.def_id()
             && def_id.is_local()
+            && (self.info.is_inside_inlined_module
+                || self.shared.cache.inlined_items.contains(&def_id))
         {
-            if self.info.is_inside_inlined_module
-                || self.shared.cache.inlined_items.contains(&def_id)
-            {
-                // For now we're forced to generate a redirect page for stripped items until
-                // `record_extern_fqn` correctly points to external items.
-                render_redirect_pages = true;
-            }
+            // For now we're forced to generate a redirect page for stripped items until
+            // `record_extern_fqn` correctly points to external items.
+            render_redirect_pages = true;
         }
         let mut title = String::new();
         if !is_module {
@@ -211,7 +209,7 @@ impl<'tcx> Context<'tcx> {
                 title.push_str(" in ");
             }
             // No need to include the namespace for primitive types and keywords
-            title.push_str(&join_with_double_colon(&self.current));
+            title.push_str(&join_path_syms(&self.current));
         };
         title.push_str(" - Rust");
         let tyname = it.type_();
@@ -254,40 +252,36 @@ impl<'tcx> Context<'tcx> {
                 &self.shared.style_files,
             )
         } else {
-            if let Some(&(ref names, ty)) = self.cache().paths.get(&it.item_id.expect_def_id()) {
-                if self.current.len() + 1 != names.len()
-                    || self.current.iter().zip(names.iter()).any(|(a, b)| a != b)
-                {
-                    // We checked that the redirection isn't pointing to the current file,
-                    // preventing an infinite redirection loop in the generated
-                    // documentation.
-
-                    let path = fmt::from_fn(|f| {
-                        for name in &names[..names.len() - 1] {
-                            write!(f, "{name}/")?;
-                        }
-                        write!(f, "{}", print_item_path(ty, names.last().unwrap().as_str()))
-                    });
-                    match self.shared.redirections {
-                        Some(ref redirections) => {
-                            let mut current_path = String::new();
-                            for name in &self.current {
-                                current_path.push_str(name.as_str());
-                                current_path.push('/');
-                            }
-                            let _ = write!(
-                                current_path,
-                                "{}",
-                                print_item_path(ty, names.last().unwrap().as_str())
-                            );
-                            redirections.borrow_mut().insert(current_path, path.to_string());
-                        }
-                        None => {
-                            return layout::redirect(&format!(
-                                "{root}{path}",
-                                root = self.root_path()
-                            ));
+            if let Some(&(ref names, ty)) = self.cache().paths.get(&it.item_id.expect_def_id())
+                && (self.current.len() + 1 != names.len()
+                    || self.current.iter().zip(names.iter()).any(|(a, b)| a != b))
+            {
+                // We checked that the redirection isn't pointing to the current file,
+                // preventing an infinite redirection loop in the generated
+                // documentation.
+
+                let path = fmt::from_fn(|f| {
+                    for name in &names[..names.len() - 1] {
+                        write!(f, "{name}/")?;
+                    }
+                    write!(f, "{}", print_item_path(ty, names.last().unwrap().as_str()))
+                });
+                match self.shared.redirections {
+                    Some(ref redirections) => {
+                        let mut current_path = String::new();
+                        for name in &self.current {
+                            current_path.push_str(name.as_str());
+                            current_path.push('/');
                         }
+                        let _ = write!(
+                            current_path,
+                            "{}",
+                            print_item_path(ty, names.last().unwrap().as_str())
+                        );
+                        redirections.borrow_mut().insert(current_path, path.to_string());
+                    }
+                    None => {
+                        return layout::redirect(&format!("{root}{path}", root = self.root_path()));
                     }
                 }
             }
@@ -762,11 +756,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         // Flush pending errors.
         self.shared.fs.close();
         let nb_errors = self.shared.errors.iter().map(|err| self.tcx().dcx().err(err)).count();
-        if nb_errors > 0 {
-            Err(Error::new(io::Error::new(io::ErrorKind::Other, "I/O error"), ""))
-        } else {
-            Ok(())
-        }
+        if nb_errors > 0 { Err(Error::new(io::Error::other("I/O error"), "")) } else { Ok(()) }
     }
 
     fn mod_item_in(&mut self, item: &clean::Item) -> Result<(), Error> {
@@ -842,7 +832,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             self.info.render_redirect_pages = item.is_stripped();
         }
 
-        let buf = self.render_item(&item, false);
+        let buf = self.render_item(item, false);
         // buf will be empty if the item is stripped and there is no redirect for it
         if !buf.is_empty() {
             let name = item.name.as_ref().unwrap();
@@ -853,7 +843,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             self.shared.fs.write(joint_dst, buf)?;
 
             if !self.info.render_redirect_pages {
-                self.shared.all.borrow_mut().append(full_path(self, &item), &item_type);
+                self.shared.all.borrow_mut().append(full_path(self, item), &item_type);
             }
             // If the item is a macro, redirect from the old macro URL (with !)
             // to the new one (without).
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 70f3f54e4c0..872dbbcd19e 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -49,6 +49,7 @@ use std::{fs, str};
 
 use askama::Template;
 use itertools::Either;
+use rustc_ast::join_path_syms;
 use rustc_attr_data_structures::{
     ConstStability, DeprecatedSince, Deprecation, RustcVersion, StabilityLevel, StableSince,
 };
@@ -74,9 +75,9 @@ use crate::formats::cache::Cache;
 use crate::formats::item_type::ItemType;
 use crate::html::escape::Escape;
 use crate::html::format::{
-    Ending, HrefError, PrintWithSpace, href, join_with_double_colon, print_abi_with_space,
-    print_constness_with_space, print_default_space, print_generic_bounds, print_where_clause,
-    visibility_print_with_space, write_str,
+    Ending, HrefError, PrintWithSpace, href, print_abi_with_space, print_constness_with_space,
+    print_default_space, print_generic_bounds, print_where_clause, visibility_print_with_space,
+    write_str,
 };
 use crate::html::markdown::{
     HeadingOffset, IdMap, Markdown, MarkdownItemInfo, MarkdownSummaryLine,
@@ -1109,7 +1110,7 @@ fn since_to_string(since: &StableSince) -> Option<String> {
     match since {
         StableSince::Version(since) => Some(since.to_string()),
         StableSince::Current => Some(RustcVersion::CURRENT.to_string()),
-        StableSince::Err => None,
+        StableSince::Err(_) => None,
     }
 }
 
@@ -1191,7 +1192,7 @@ fn render_assoc_item(
 // a whitespace prefix and newline.
 fn render_attributes_in_pre(it: &clean::Item, prefix: &str, cx: &Context<'_>) -> impl fmt::Display {
     fmt::from_fn(move |f| {
-        for a in it.attributes(cx.tcx(), cx.cache(), false) {
+        for a in it.attributes(cx.tcx(), cx.cache()) {
             writeln!(f, "{prefix}{a}")?;
         }
         Ok(())
@@ -1207,7 +1208,7 @@ fn render_code_attribute(code_attr: CodeAttribute, w: &mut impl fmt::Write) {
 // When an attribute is rendered inside a <code> tag, it is formatted using
 // a div to produce a newline after it.
 fn render_attributes_in_code(w: &mut impl fmt::Write, it: &clean::Item, cx: &Context<'_>) {
-    for attr in it.attributes(cx.tcx(), cx.cache(), false) {
+    for attr in it.attributes(cx.tcx(), cx.cache()) {
         render_code_attribute(CodeAttribute(attr), w);
     }
 }
@@ -1219,7 +1220,7 @@ fn render_repr_attributes_in_code(
     def_id: DefId,
     item_type: ItemType,
 ) {
-    if let Some(repr) = clean::repr_attributes(cx.tcx(), cx.cache(), def_id, item_type, false) {
+    if let Some(repr) = clean::repr_attributes(cx.tcx(), cx.cache(), def_id, item_type) {
         render_code_attribute(CodeAttribute(repr), w);
     }
 }
@@ -1482,10 +1483,10 @@ fn render_deref_methods(
             }
         }
         render_assoc_items_inner(&mut w, cx, container_item, did, what, derefs);
-    } else if let Some(prim) = target.primitive_type() {
-        if let Some(&did) = cache.primitive_locations.get(&prim) {
-            render_assoc_items_inner(&mut w, cx, container_item, did, what, derefs);
-        }
+    } else if let Some(prim) = target.primitive_type()
+        && let Some(&did) = cache.primitive_locations.get(&prim)
+    {
+        render_assoc_items_inner(&mut w, cx, container_item, did, what, derefs);
     }
 }
 
@@ -2057,21 +2058,20 @@ fn render_impl(
         // default items which weren't overridden in the implementation block.
         // We don't emit documentation for default items if they appear in the
         // Implementations on Foreign Types or Implementors sections.
-        if rendering_params.show_default_items {
-            if let Some(t) = trait_
-                && !impl_.is_negative_trait_impl()
-            {
-                render_default_items(
-                    &mut default_impl_items,
-                    &mut impl_items,
-                    cx,
-                    t,
-                    impl_,
-                    &i.impl_item,
-                    render_mode,
-                    rendering_params,
-                )?;
-            }
+        if rendering_params.show_default_items
+            && let Some(t) = trait_
+            && !impl_.is_negative_trait_impl()
+        {
+            render_default_items(
+                &mut default_impl_items,
+                &mut impl_items,
+                cx,
+                t,
+                impl_,
+                &i.impl_item,
+                render_mode,
+                rendering_params,
+            )?;
         }
         if render_mode == RenderMode::Normal {
             let toggled = !(impl_items.is_empty() && default_impl_items.is_empty());
@@ -2555,7 +2555,7 @@ fn collect_paths_for_type(first_ty: &clean::Type, cache: &Cache) -> Vec<String>
         let fqp = cache.exact_paths.get(&did).or_else(get_extern);
 
         if let Some(path) = fqp {
-            out.push(join_with_double_colon(path));
+            out.push(join_path_syms(path));
         }
     };
 
@@ -2569,7 +2569,7 @@ fn collect_paths_for_type(first_ty: &clean::Type, cache: &Cache) -> Vec<String>
         match ty {
             clean::Type::Path { path } => process_path(path.def_id()),
             clean::Type::Tuple(tys) => {
-                work.extend(tys.into_iter());
+                work.extend(tys.iter());
             }
             clean::Type::Slice(ty) => {
                 work.push_back(ty);
diff --git a/src/librustdoc/html/render/ordered_json.rs b/src/librustdoc/html/render/ordered_json.rs
index d1dddfebc83..be51dad1c2b 100644
--- a/src/librustdoc/html/render/ordered_json.rs
+++ b/src/librustdoc/html/render/ordered_json.rs
@@ -25,7 +25,7 @@ impl OrderedJson {
             .into_iter()
             .sorted_unstable_by(|a, b| a.borrow().cmp(b.borrow()))
             .format_with(",", |item, f| f(item.borrow()));
-        Self(format!("[{}]", items))
+        Self(format!("[{items}]"))
     }
 
     pub(crate) fn array_unsorted<T: Borrow<Self>, I: IntoIterator<Item = T>>(items: I) -> Self {
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index e33bdc0db32..02ee34aaac6 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -4,6 +4,7 @@ use std::iter;
 
 use askama::Template;
 use rustc_abi::VariantIdx;
+use rustc_ast::join_path_syms;
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_hir as hir;
 use rustc_hir::def::CtorKind;
@@ -30,8 +31,8 @@ use crate::formats::Impl;
 use crate::formats::item_type::ItemType;
 use crate::html::escape::{Escape, EscapeBodyTextWithWbr};
 use crate::html::format::{
-    Ending, PrintWithSpace, join_with_double_colon, print_abi_with_space,
-    print_constness_with_space, print_where_clause, visibility_print_with_space,
+    Ending, PrintWithSpace, print_abi_with_space, print_constness_with_space, print_where_clause,
+    visibility_print_with_space,
 };
 use crate::html::markdown::{HeadingOffset, MarkdownSummaryLine};
 use crate::html::render::{document_full, document_item_info};
@@ -1424,7 +1425,7 @@ fn item_type_alias(cx: &Context<'_>, it: &clean::Item, t: &clean::TypeAlias) ->
                 iter::repeat_n("..", cx.current.len()).chain(iter::once("type.impl")).collect();
             js_src_path.extend(target_fqp[..target_fqp.len() - 1].iter().copied());
             js_src_path.push_fmt(format_args!("{target_type}.{}.js", target_fqp.last().unwrap()));
-            let self_path = fmt::from_fn(|f| self_fqp.iter().joined("::", f));
+            let self_path = join_path_syms(self_fqp);
             write!(
                 w,
                 "<script src=\"{src}\" data-self-path=\"{self_path}\" async></script>",
@@ -1450,7 +1451,7 @@ item_template!(
 
 impl<'a, 'cx: 'a> ItemUnion<'a, 'cx> {
     fn render_union(&self) -> impl Display {
-        render_union(self.it, Some(&self.generics), &self.fields, self.cx)
+        render_union(self.it, Some(self.generics), self.fields, self.cx)
     }
 
     fn document_field(&self, field: &'a clean::Item) -> impl Display {
@@ -1487,12 +1488,11 @@ impl<'a, 'cx: 'a> ItemUnion<'a, 'cx> {
                     self.cx.cache(),
                     self.def_id,
                     ItemType::Union,
-                    false,
                 ) {
                     writeln!(f, "{repr}")?;
                 };
             } else {
-                for a in self.it.attributes(self.cx.tcx(), self.cx.cache(), false) {
+                for a in self.it.attributes(self.cx.tcx(), self.cx.cache()) {
                     writeln!(f, "{a}")?;
                 }
             }
@@ -1982,16 +1982,14 @@ fn item_constant(
                 w.write_str(";")?;
             }
 
-            if !is_literal {
-                if let Some(value) = &value {
-                    let value_lowercase = value.to_lowercase();
-                    let expr_lowercase = expr.to_lowercase();
+            if !is_literal && let Some(value) = &value {
+                let value_lowercase = value.to_lowercase();
+                let expr_lowercase = expr.to_lowercase();
 
-                    if value_lowercase != expr_lowercase
-                        && value_lowercase.trim_end_matches("i32") != expr_lowercase
-                    {
-                        write!(w, " // {value}", value = Escape(value))?;
-                    }
+                if value_lowercase != expr_lowercase
+                    && value_lowercase.trim_end_matches("i32") != expr_lowercase
+                {
+                    write!(w, " // {value}", value = Escape(value))?;
                 }
             }
             Ok::<(), fmt::Error>(())
@@ -2071,41 +2069,39 @@ fn item_fields(
                 _ => None,
             })
             .peekable();
-        if let None | Some(CtorKind::Fn) = ctor_kind {
-            if fields.peek().is_some() {
-                let title = format!(
-                    "{}{}",
-                    if ctor_kind.is_none() { "Fields" } else { "Tuple Fields" },
-                    document_non_exhaustive_header(it),
-                );
+        if let None | Some(CtorKind::Fn) = ctor_kind
+            && fields.peek().is_some()
+        {
+            let title = format!(
+                "{}{}",
+                if ctor_kind.is_none() { "Fields" } else { "Tuple Fields" },
+                document_non_exhaustive_header(it),
+            );
+            write!(
+                w,
+                "{}",
+                write_section_heading(
+                    &title,
+                    "fields",
+                    Some("fields"),
+                    document_non_exhaustive(it)
+                )
+            )?;
+            for (index, (field, ty)) in fields.enumerate() {
+                let field_name =
+                    field.name.map_or_else(|| index.to_string(), |sym| sym.as_str().to_string());
+                let id = cx.derive_id(format!("{typ}.{field_name}", typ = ItemType::StructField));
                 write!(
                     w,
-                    "{}",
-                    write_section_heading(
-                        &title,
-                        "fields",
-                        Some("fields"),
-                        document_non_exhaustive(it)
-                    )
+                    "<span id=\"{id}\" class=\"{item_type} section-header\">\
+                        <a href=\"#{id}\" class=\"anchor field\">§</a>\
+                        <code>{field_name}: {ty}</code>\
+                    </span>\
+                    {doc}",
+                    item_type = ItemType::StructField,
+                    ty = ty.print(cx),
+                    doc = document(cx, field, Some(it), HeadingOffset::H3),
                 )?;
-                for (index, (field, ty)) in fields.enumerate() {
-                    let field_name = field
-                        .name
-                        .map_or_else(|| index.to_string(), |sym| sym.as_str().to_string());
-                    let id =
-                        cx.derive_id(format!("{typ}.{field_name}", typ = ItemType::StructField));
-                    write!(
-                        w,
-                        "<span id=\"{id}\" class=\"{item_type} section-header\">\
-                            <a href=\"#{id}\" class=\"anchor field\">§</a>\
-                            <code>{field_name}: {ty}</code>\
-                        </span>\
-                        {doc}",
-                        item_type = ItemType::StructField,
-                        ty = ty.print(cx),
-                        doc = document(cx, field, Some(it), HeadingOffset::H3),
-                    )?;
-                }
             }
         }
         Ok(())
@@ -2257,7 +2253,7 @@ pub(crate) fn compare_names(left: &str, right: &str) -> Ordering {
 }
 
 pub(super) fn full_path(cx: &Context<'_>, item: &clean::Item) -> String {
-    let mut s = join_with_double_colon(&cx.current);
+    let mut s = join_path_syms(&cx.current);
     s.push_str("::");
     s.push_str(item.name.unwrap().as_str());
     s
diff --git a/src/librustdoc/html/render/search_index.rs b/src/librustdoc/html/render/search_index.rs
index aff8684ee3a..3c9be29ccc3 100644
--- a/src/librustdoc/html/render/search_index.rs
+++ b/src/librustdoc/html/render/search_index.rs
@@ -4,6 +4,7 @@ use std::collections::hash_map::Entry;
 use std::collections::{BTreeMap, VecDeque};
 
 use encode::{bitmap_to_string, write_vlqhex_to_string};
+use rustc_ast::join_path_syms;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::DefId;
@@ -17,7 +18,6 @@ use crate::clean::types::{Function, Generics, ItemId, Type, WherePredicate};
 use crate::clean::{self, utils};
 use crate::formats::cache::{Cache, OrphanImplItem};
 use crate::formats::item_type::ItemType;
-use crate::html::format::join_with_double_colon;
 use crate::html::markdown::short_markdown_summary;
 use crate::html::render::ordered_json::OrderedJson;
 use crate::html::render::{self, IndexItem, IndexItemFunctionType, RenderType, RenderTypeId};
@@ -78,7 +78,7 @@ pub(crate) fn build_index(
                 ty: item.type_(),
                 defid: item.item_id.as_def_id(),
                 name: item.name.unwrap(),
-                path: join_with_double_colon(&fqp[..fqp.len() - 1]),
+                path: join_path_syms(&fqp[..fqp.len() - 1]),
                 desc,
                 parent: Some(parent),
                 parent_idx: None,
@@ -116,7 +116,7 @@ pub(crate) fn build_index(
     // Set up alias indexes.
     for (i, item) in cache.search_index.iter().enumerate() {
         for alias in &item.aliases[..] {
-            aliases.entry(alias.as_str().to_lowercase()).or_default().push(i);
+            aliases.entry(alias.to_string()).or_default().push(i);
         }
     }
 
@@ -416,7 +416,7 @@ pub(crate) fn build_index(
                             if fqp.len() < 2 {
                                 return None;
                             }
-                            join_with_double_colon(&fqp[..fqp.len() - 1])
+                            join_path_syms(&fqp[..fqp.len() - 1])
                         };
                     if path == item.path {
                         return None;
@@ -427,10 +427,10 @@ pub(crate) fn build_index(
                 let i = <isize as TryInto<usize>>::try_into(parent_idx).unwrap();
                 item.path = {
                     let p = &crate_paths[i].1;
-                    join_with_double_colon(&p[..p.len() - 1])
+                    join_path_syms(&p[..p.len() - 1])
                 };
                 item.exact_path =
-                    crate_paths[i].2.as_ref().map(|xp| join_with_double_colon(&xp[..xp.len() - 1]));
+                    crate_paths[i].2.as_ref().map(|xp| join_path_syms(&xp[..xp.len() - 1]));
             }
 
             // Omit the parent path if it is same to that of the prior item.
@@ -549,11 +549,11 @@ pub(crate) fn build_index(
                     });
                     continue;
                 }
-                let full_path = join_with_double_colon(&path[..path.len() - 1]);
+                let full_path = join_path_syms(&path[..path.len() - 1]);
                 let full_exact_path = exact
                     .as_ref()
                     .filter(|exact| exact.last() == path.last() && exact.len() >= 2)
-                    .map(|exact| join_with_double_colon(&exact[..exact.len() - 1]));
+                    .map(|exact| join_path_syms(&exact[..exact.len() - 1]));
                 let exact_path = extra_paths.len() + self.items.len();
                 let exact_path = full_exact_path.as_ref().map(|full_exact_path| match extra_paths
                     .entry(full_exact_path.clone())
diff --git a/src/librustdoc/html/render/sidebar.rs b/src/librustdoc/html/render/sidebar.rs
index 91540e06e33..b9f5ada417c 100644
--- a/src/librustdoc/html/render/sidebar.rs
+++ b/src/librustdoc/html/render/sidebar.rs
@@ -541,7 +541,7 @@ fn sidebar_deref_methods<'a>(
                 .iter()
                 .filter(|i| {
                     i.inner_impl().trait_.is_none()
-                        && real_target.is_doc_subtype_of(&i.inner_impl().for_, &c)
+                        && real_target.is_doc_subtype_of(&i.inner_impl().for_, c)
                 })
                 .flat_map(|i| get_methods(i.inner_impl(), true, used_links, deref_mut, cx.tcx()))
                 .collect::<Vec<_>>();
diff --git a/src/librustdoc/html/render/sorted_template.rs b/src/librustdoc/html/render/sorted_template.rs
index a7b954ab70b..659c5e6093b 100644
--- a/src/librustdoc/html/render/sorted_template.rs
+++ b/src/librustdoc/html/render/sorted_template.rs
@@ -63,7 +63,8 @@ impl<F: FileFormat> fmt::Display for SortedTemplate<F> {
         for (p, fragment) in self.fragments.iter().with_position() {
             let mut f = DeltaWriter { inner: &mut f, delta: 0 };
             let sep = if matches!(p, Position::First | Position::Only) { "" } else { F::SEPARATOR };
-            write!(f, "{}{}", sep, fragment)?;
+            f.write_str(sep)?;
+            f.write_str(fragment)?;
             fragment_lengths.push(f.delta);
         }
         let offset = Offset { start: self.before.len(), fragment_lengths };
diff --git a/src/librustdoc/html/render/write_shared.rs b/src/librustdoc/html/render/write_shared.rs
index 0078671fcc5..1f691392b17 100644
--- a/src/librustdoc/html/render/write_shared.rs
+++ b/src/librustdoc/html/render/write_shared.rs
@@ -26,6 +26,7 @@ use std::{fmt, fs};
 
 use indexmap::IndexMap;
 use regex::Regex;
+use rustc_ast::join_path_syms;
 use rustc_data_structures::flock;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_middle::ty::TyCtxt;
@@ -43,7 +44,6 @@ use crate::docfs::PathError;
 use crate::error::Error;
 use crate::formats::Impl;
 use crate::formats::item_type::ItemType;
-use crate::html::format::join_with_double_colon;
 use crate::html::layout;
 use crate::html::render::ordered_json::{EscapedJson, OrderedJson};
 use crate::html::render::search_index::{SerializedSearchIndex, build_index};
@@ -608,7 +608,7 @@ impl TypeAliasPart {
                     for &(type_alias_fqp, type_alias_item) in type_aliases {
                         cx.id_map.borrow_mut().clear();
                         cx.deref_id_map.borrow_mut().clear();
-                        let type_alias_fqp = join_with_double_colon(&type_alias_fqp);
+                        let type_alias_fqp = join_path_syms(type_alias_fqp);
                         if let Some(ret) = &mut ret {
                             ret.aliases.push(type_alias_fqp);
                         } else {
diff --git a/src/librustdoc/html/static/js/rustdoc.d.ts b/src/librustdoc/html/static/js/rustdoc.d.ts
index ca2512e5ab6..a9589764547 100644
--- a/src/librustdoc/html/static/js/rustdoc.d.ts
+++ b/src/librustdoc/html/static/js/rustdoc.d.ts
@@ -219,6 +219,8 @@ declare namespace rustdoc {
         crate: string,
         descShard: SearchDescShard,
         id: number,
+        // This is the name of the item. For doc aliases, if you want the name of the aliased
+        // item, take a look at `Row.original.name`.
         name: string,
         normalizedName: string,
         word: string,
@@ -227,6 +229,11 @@ declare namespace rustdoc {
         path: string,
         ty: number,
         type: FunctionSearchType | null,
+        descIndex: number,
+        bitIndex: number,
+        implDisambiguator: String | null,
+        is_alias?: boolean,
+        original?: Row,
     }
 
     /**
diff --git a/src/librustdoc/html/static/js/search.js b/src/librustdoc/html/static/js/search.js
index 15cad31f555..2caf214ff73 100644
--- a/src/librustdoc/html/static/js/search.js
+++ b/src/librustdoc/html/static/js/search.js
@@ -830,7 +830,7 @@ function createQueryElement(query, parserState, name, generics, isInGenerics) {
  */
 function makePrimitiveElement(name, extra) {
     return Object.assign({
-        name: name,
+        name,
         id: null,
         fullPath: [name],
         pathWithoutLast: [],
@@ -1483,6 +1483,7 @@ class DocSearch {
          */
         this.assocTypeIdNameMap = new Map();
         this.ALIASES = new Map();
+        this.FOUND_ALIASES = new Set();
         this.rootPath = rootPath;
         this.searchState = searchState;
 
@@ -2030,6 +2031,8 @@ class DocSearch {
         // normalized names, type signature objects and fingerprints, and aliases.
         id = 0;
 
+        /** @type {Array<[string, { [key: string]: Array<number> },  number]>} */
+        const allAliases = [];
         for (const [crate, crateCorpus] of rawSearchIndex) {
             // a string representing the lengths of each description shard
             // a string representing the list of function types
@@ -2178,10 +2181,10 @@ class DocSearch {
                 paths[i] = { ty, name, path, exactPath, unboxFlag };
             }
 
-            // convert `item*` into an object form, and construct word indices.
+            // Convert `item*` into an object form, and construct word indices.
             //
-            // before any analysis is performed lets gather the search terms to
-            // search against apart from the rest of the data.  This is a quick
+            // Before any analysis is performed, let's gather the search terms to
+            // search against apart from the rest of the data. This is a quick
             // operation that is cached for the life of the page state so that
             // all other search operations have access to this cached data for
             // faster analysis operations
@@ -2269,29 +2272,58 @@ class DocSearch {
             }
 
             if (aliases) {
-                const currentCrateAliases = new Map();
-                this.ALIASES.set(crate, currentCrateAliases);
-                for (const alias_name in aliases) {
-                    if (!Object.prototype.hasOwnProperty.call(aliases, alias_name)) {
-                        continue;
-                    }
-
-                    /** @type{number[]} */
-                    let currentNameAliases;
-                    if (currentCrateAliases.has(alias_name)) {
-                        currentNameAliases = currentCrateAliases.get(alias_name);
-                    } else {
-                        currentNameAliases = [];
-                        currentCrateAliases.set(alias_name, currentNameAliases);
-                    }
-                    for (const local_alias of aliases[alias_name]) {
-                        currentNameAliases.push(local_alias + currentIndex);
-                    }
-                }
+                // We need to add the aliases in `searchIndex` after we finished filling it
+                // to not mess up indexes.
+                allAliases.push([crate, aliases, currentIndex]);
             }
             currentIndex += itemTypes.length;
             this.searchState.descShards.set(crate, descShardList);
         }
+
+        for (const [crate, aliases, index] of allAliases) {
+            for (const [alias_name, alias_refs] of Object.entries(aliases)) {
+                if (!this.ALIASES.has(crate)) {
+                    this.ALIASES.set(crate, new Map());
+                }
+                const word = alias_name.toLowerCase();
+                const crate_alias_map = this.ALIASES.get(crate);
+                if (!crate_alias_map.has(word)) {
+                    crate_alias_map.set(word, []);
+                }
+                const aliases_map = crate_alias_map.get(word);
+
+                const normalizedName = word.indexOf("_") === -1 ? word : word.replace(/_/g, "");
+                for (const alias of alias_refs) {
+                    const originalIndex = alias + index;
+                    const original = searchIndex[originalIndex];
+                    /** @type {rustdoc.Row} */
+                    const row = {
+                        crate,
+                        name: alias_name,
+                        normalizedName,
+                        is_alias: true,
+                        ty: original.ty,
+                        type: original.type,
+                        paramNames: [],
+                        word,
+                        id,
+                        parent: undefined,
+                        original,
+                        path: "",
+                        implDisambiguator: original.implDisambiguator,
+                        // Needed to load the description of the original item.
+                        // @ts-ignore
+                        descShard: original.descShard,
+                        descIndex: original.descIndex,
+                        bitIndex: original.bitIndex,
+                    };
+                    aliases_map.push(row);
+                    this.nameTrie.insert(normalizedName, id, this.tailTable);
+                    id += 1;
+                    searchIndex.push(row);
+                }
+            }
+        }
         // Drop the (rather large) hash table used for reusing function items
         this.TYPES_POOL = new Map();
         return searchIndex;
@@ -2536,6 +2568,8 @@ class DocSearch {
             parsedQuery.elems.reduce((acc, next) => acc + next.pathLast.length, 0) +
             parsedQuery.returned.reduce((acc, next) => acc + next.pathLast.length, 0);
         const maxEditDistance = Math.floor(queryLen / 3);
+        // We reinitialize the `FOUND_ALIASES` map.
+        this.FOUND_ALIASES.clear();
 
         /**
          * @type {Map<string, number>}
@@ -2695,6 +2729,10 @@ class DocSearch {
         const buildHrefAndPath = item => {
             let displayPath;
             let href;
+            if (item.is_alias) {
+                this.FOUND_ALIASES.add(item.word);
+                item = item.original;
+            }
             const type = itemTypes[item.ty];
             const name = item.name;
             let path = item.path;
@@ -3198,8 +3236,7 @@ class DocSearch {
                 result.item = this.searchIndex[result.id];
                 result.word = this.searchIndex[result.id].word;
                 if (isReturnTypeQuery) {
-                    // we are doing a return-type based search,
-                    // deprioritize "clone-like" results,
+                    // We are doing a return-type based search, deprioritize "clone-like" results,
                     // ie. functions that also take the queried type as an argument.
                     const resultItemType = result.item && result.item.type;
                     if (!resultItemType) {
@@ -4259,28 +4296,13 @@ class DocSearch {
             return false;
         }
 
-        // this does not yet have a type in `rustdoc.d.ts`.
-        // @ts-expect-error
-        function createAliasFromItem(item) {
-            return {
-                crate: item.crate,
-                name: item.name,
-                path: item.path,
-                descShard: item.descShard,
-                descIndex: item.descIndex,
-                exactPath: item.exactPath,
-                ty: item.ty,
-                parent: item.parent,
-                type: item.type,
-                is_alias: true,
-                bitIndex: item.bitIndex,
-                implDisambiguator: item.implDisambiguator,
-            };
-        }
-
         // @ts-expect-error
         const handleAliases = async(ret, query, filterCrates, currentCrate) => {
             const lowerQuery = query.toLowerCase();
+            if (this.FOUND_ALIASES.has(lowerQuery)) {
+                return;
+            }
+            this.FOUND_ALIASES.add(lowerQuery);
             // We separate aliases and crate aliases because we want to have current crate
             // aliases to be before the others in the displayed results.
             // @ts-expect-error
@@ -4292,7 +4314,7 @@ class DocSearch {
                     && this.ALIASES.get(filterCrates).has(lowerQuery)) {
                     const query_aliases = this.ALIASES.get(filterCrates).get(lowerQuery);
                     for (const alias of query_aliases) {
-                        aliases.push(createAliasFromItem(this.searchIndex[alias]));
+                        aliases.push(alias);
                     }
                 }
             } else {
@@ -4302,7 +4324,7 @@ class DocSearch {
                         const pushTo = crate === currentCrate ? crateAliases : aliases;
                         const query_aliases = crateAliasesIndex.get(lowerQuery);
                         for (const alias of query_aliases) {
-                            pushTo.push(createAliasFromItem(this.searchIndex[alias]));
+                            pushTo.push(alias);
                         }
                     }
                 }
@@ -4310,9 +4332,9 @@ class DocSearch {
 
             // @ts-expect-error
             const sortFunc = (aaa, bbb) => {
-                if (aaa.path < bbb.path) {
+                if (aaa.original.path < bbb.original.path) {
                     return 1;
-                } else if (aaa.path === bbb.path) {
+                } else if (aaa.original.path === bbb.original.path) {
                     return 0;
                 }
                 return -1;
@@ -4322,20 +4344,9 @@ class DocSearch {
             aliases.sort(sortFunc);
 
             // @ts-expect-error
-            const fetchDesc = alias => {
-                // @ts-expect-error
-                return this.searchIndexEmptyDesc.get(alias.crate).contains(alias.bitIndex) ?
-                    "" : this.searchState.loadDesc(alias);
-            };
-            const [crateDescs, descs] = await Promise.all([
-                // @ts-expect-error
-                Promise.all(crateAliases.map(fetchDesc)),
-                Promise.all(aliases.map(fetchDesc)),
-            ]);
-
-            // @ts-expect-error
             const pushFunc = alias => {
-                alias.alias = query;
+                // Cloning `alias` to prevent its fields to be updated.
+                alias = {...alias};
                 const res = buildHrefAndPath(alias);
                 alias.displayPath = pathSplitter(res[0]);
                 alias.fullPath = alias.displayPath + alias.name;
@@ -4347,16 +4358,8 @@ class DocSearch {
                 }
             };
 
-            aliases.forEach((alias, i) => {
-                // @ts-expect-error
-                alias.desc = descs[i];
-            });
             aliases.forEach(pushFunc);
             // @ts-expect-error
-            crateAliases.forEach((alias, i) => {
-                alias.desc = crateDescs[i];
-            });
-            // @ts-expect-error
             crateAliases.forEach(pushFunc);
         };
 
@@ -4802,7 +4805,7 @@ async function addTab(array, query, display) {
         output.className = "search-results " + extraClass;
 
         const lis = Promise.all(array.map(async item => {
-            const name = item.name;
+            const name = item.is_alias ? item.original.name : item.name;
             const type = itemTypes[item.ty];
             const longType = longItemTypes[item.ty];
             const typeName = longType.length !== 0 ? `${longType}` : "?";
@@ -4822,7 +4825,7 @@ async function addTab(array, query, display) {
             let alias = " ";
             if (item.is_alias) {
                 alias = ` <div class="alias">\
-<b>${item.alias}</b><i class="grey">&nbsp;- see&nbsp;</i>\
+<b>${item.name}</b><i class="grey">&nbsp;- see&nbsp;</i>\
 </div>`;
             }
             resultName.insertAdjacentHTML(
@@ -5201,6 +5204,7 @@ function registerSearchEvents() {
         if (searchState.input.value.length === 0) {
             searchState.hideResults();
         } else {
+            // @ts-ignore
             searchState.timeout = setTimeout(search, 500);
         }
     };
@@ -5842,8 +5846,8 @@ Lev1TParametricDescription.prototype.offsetIncrs3 = /*2 bits per value */ new In
 // be called ONLY when the whole file has been parsed and loaded.
 
 // @ts-expect-error
-function initSearch(searchIndx) {
-    rawSearchIndex = searchIndx;
+function initSearch(searchIndex) {
+    rawSearchIndex = searchIndex;
     if (typeof window !== "undefined") {
         // @ts-expect-error
         docSearch = new DocSearch(rawSearchIndex, ROOT_PATH, searchState);
diff --git a/src/librustdoc/html/url_parts_builder.rs b/src/librustdoc/html/url_parts_builder.rs
index 9a533827441..705fa498e8d 100644
--- a/src/librustdoc/html/url_parts_builder.rs
+++ b/src/librustdoc/html/url_parts_builder.rs
@@ -117,7 +117,7 @@ impl UrlPartsBuilder {
 
 /// This is just a guess at the average length of a URL part,
 /// used for [`String::with_capacity`] calls in the [`FromIterator`]
-/// and [`Extend`] impls, and for [estimating item path lengths].
+/// and [`Extend`] impls.
 ///
 /// The value `8` was chosen for two main reasons:
 ///
@@ -125,18 +125,8 @@ impl UrlPartsBuilder {
 /// * jemalloc's size classes are all multiples of eight,
 ///   which means that the amount of memory it allocates will often match
 ///   the amount requested, avoiding wasted bytes.
-///
-/// [estimating item path lengths]: estimate_item_path_byte_length
 const AVG_PART_LENGTH: usize = 8;
 
-/// Estimate the number of bytes in an item's path, based on how many segments it has.
-///
-/// **Note:** This is only to be used with, e.g., [`String::with_capacity()`];
-/// the return value is just a rough estimate.
-pub(crate) const fn estimate_item_path_byte_length(segment_count: usize) -> usize {
-    AVG_PART_LENGTH * segment_count
-}
-
 impl<'a> FromIterator<&'a str> for UrlPartsBuilder {
     fn from_iter<T: IntoIterator<Item = &'a str>>(iter: T) -> Self {
         let iter = iter.into_iter();
diff --git a/src/librustdoc/json/conversions.rs b/src/librustdoc/json/conversions.rs
index e7163bead92..08bc0bb1950 100644
--- a/src/librustdoc/json/conversions.rs
+++ b/src/librustdoc/json/conversions.rs
@@ -5,10 +5,12 @@
 use rustc_abi::ExternAbi;
 use rustc_ast::ast;
 use rustc_attr_data_structures::{self as attrs, DeprecatedSince};
+use rustc_hir as hir;
 use rustc_hir::def::CtorKind;
 use rustc_hir::def_id::DefId;
 use rustc_hir::{HeaderSafety, Safety};
 use rustc_metadata::rendered_const;
+use rustc_middle::ty::TyCtxt;
 use rustc_middle::{bug, ty};
 use rustc_span::{Pos, kw, sym};
 use rustdoc_json_types::*;
@@ -39,11 +41,16 @@ impl JsonRenderer<'_> {
             })
             .collect();
         let docs = item.opt_doc_value();
-        let attrs = item.attributes(self.tcx, &self.cache, true);
+        let attrs = item
+            .attrs
+            .other_attrs
+            .iter()
+            .filter_map(|a| maybe_from_hir_attr(a, item.item_id, self.tcx))
+            .collect();
         let span = item.span(self.tcx);
         let visibility = item.visibility(self.tcx);
         let clean::ItemInner { name, item_id, .. } = *item.inner;
-        let id = self.id_from_item(&item);
+        let id = self.id_from_item(item);
         let inner = match item.kind {
             clean::KeywordItem => return None,
             clean::StrippedItem(ref inner) => {
@@ -79,14 +86,14 @@ impl JsonRenderer<'_> {
         items
             .iter()
             .filter(|i| !i.is_stripped() && !i.is_keyword())
-            .map(|i| self.id_from_item(&i))
+            .map(|i| self.id_from_item(i))
             .collect()
     }
 
     fn ids_keeping_stripped(&self, items: &[clean::Item]) -> Vec<Option<Id>> {
         items
             .iter()
-            .map(|i| (!i.is_stripped() && !i.is_keyword()).then(|| self.id_from_item(&i)))
+            .map(|i| (!i.is_stripped() && !i.is_keyword()).then(|| self.id_from_item(i)))
             .collect()
     }
 }
@@ -351,12 +358,12 @@ impl FromClean<clean::Struct> for Struct {
         let clean::Struct { ctor_kind, generics, fields } = struct_;
 
         let kind = match ctor_kind {
-            Some(CtorKind::Fn) => StructKind::Tuple(renderer.ids_keeping_stripped(&fields)),
+            Some(CtorKind::Fn) => StructKind::Tuple(renderer.ids_keeping_stripped(fields)),
             Some(CtorKind::Const) => {
                 assert!(fields.is_empty());
                 StructKind::Unit
             }
-            None => StructKind::Plain { fields: renderer.ids(&fields), has_stripped_fields },
+            None => StructKind::Plain { fields: renderer.ids(fields), has_stripped_fields },
         };
 
         Struct {
@@ -374,7 +381,7 @@ impl FromClean<clean::Union> for Union {
         Union {
             generics: generics.into_json(renderer),
             has_stripped_fields,
-            fields: renderer.ids(&fields),
+            fields: renderer.ids(fields),
             impls: Vec::new(), // Added in JsonRenderer::item
         }
     }
@@ -652,7 +659,7 @@ impl FromClean<clean::FnDecl> for FunctionSignature {
         let clean::FnDecl { inputs, output, c_variadic } = decl;
         FunctionSignature {
             inputs: inputs
-                .into_iter()
+                .iter()
                 .map(|param| {
                     // `_` is the most sensible name for missing param names.
                     let name = param.name.unwrap_or(kw::Underscore).to_string();
@@ -677,7 +684,7 @@ impl FromClean<clean::Trait> for Trait {
             is_auto,
             is_unsafe,
             is_dyn_compatible,
-            items: renderer.ids(&items),
+            items: renderer.ids(items),
             generics: generics.into_json(renderer),
             bounds: bounds.into_json(renderer),
             implementations: Vec::new(), // Added in JsonRenderer::item
@@ -720,7 +727,7 @@ impl FromClean<clean::Impl> for Impl {
                 .collect(),
             trait_: trait_.into_json(renderer),
             for_: for_.into_json(renderer),
-            items: renderer.ids(&items),
+            items: renderer.ids(items),
             is_negative,
             is_synthetic,
             blanket_impl: blanket_impl.map(|x| x.into_json(renderer)),
@@ -763,7 +770,7 @@ impl FromClean<clean::Variant> for Variant {
 
         let kind = match &variant.kind {
             CLike => VariantKind::Plain,
-            Tuple(fields) => VariantKind::Tuple(renderer.ids_keeping_stripped(&fields)),
+            Tuple(fields) => VariantKind::Tuple(renderer.ids_keeping_stripped(fields)),
             Struct(s) => VariantKind::Struct {
                 has_stripped_fields: s.has_stripped_entries(),
                 fields: renderer.ids(&s.fields),
@@ -886,3 +893,93 @@ impl FromClean<ItemType> for ItemKind {
         }
     }
 }
+
+/// Maybe convert a attribute from hir to json.
+///
+/// Returns `None` if the attribute shouldn't be in the output.
+fn maybe_from_hir_attr(
+    attr: &hir::Attribute,
+    item_id: ItemId,
+    tcx: TyCtxt<'_>,
+) -> Option<Attribute> {
+    use attrs::AttributeKind as AK;
+
+    let kind = match attr {
+        hir::Attribute::Parsed(kind) => kind,
+
+        hir::Attribute::Unparsed(_) => {
+            // FIXME: We should handle `#[doc(hidden)]`.
+            return Some(other_attr(tcx, attr));
+        }
+    };
+
+    Some(match kind {
+        AK::Deprecation { .. } => return None, // Handled separately into Item::deprecation.
+        AK::DocComment { .. } => unreachable!("doc comments stripped out earlier"),
+
+        AK::MustUse { reason, span: _ } => {
+            Attribute::MustUse { reason: reason.map(|s| s.to_string()) }
+        }
+        AK::Repr { .. } => repr_attr(
+            tcx,
+            item_id.as_def_id().expect("all items that could have #[repr] have a DefId"),
+        ),
+        AK::ExportName { name, span: _ } => Attribute::ExportName(name.to_string()),
+        AK::LinkSection { name, span: _ } => Attribute::LinkSection(name.to_string()),
+        AK::TargetFeature(features, _span) => Attribute::TargetFeature {
+            enable: features.iter().map(|(feat, _span)| feat.to_string()).collect(),
+        },
+
+        AK::NoMangle(_) => Attribute::NoMangle,
+        AK::NonExhaustive(_) => Attribute::NonExhaustive,
+        AK::AutomaticallyDerived(_) => Attribute::AutomaticallyDerived,
+
+        _ => other_attr(tcx, attr),
+    })
+}
+
+fn other_attr(tcx: TyCtxt<'_>, attr: &hir::Attribute) -> Attribute {
+    let mut s = rustc_hir_pretty::attribute_to_string(&tcx, attr);
+    assert_eq!(s.pop(), Some('\n'));
+    Attribute::Other(s)
+}
+
+fn repr_attr(tcx: TyCtxt<'_>, def_id: DefId) -> Attribute {
+    let repr = tcx.adt_def(def_id).repr();
+
+    let kind = if repr.c() {
+        ReprKind::C
+    } else if repr.transparent() {
+        ReprKind::Transparent
+    } else if repr.simd() {
+        ReprKind::Simd
+    } else {
+        ReprKind::Rust
+    };
+
+    let align = repr.align.map(|a| a.bytes());
+    let packed = repr.pack.map(|p| p.bytes());
+    let int = repr.int.map(format_integer_type);
+
+    Attribute::Repr(AttributeRepr { kind, align, packed, int })
+}
+
+fn format_integer_type(it: rustc_abi::IntegerType) -> String {
+    use rustc_abi::Integer::*;
+    use rustc_abi::IntegerType::*;
+    match it {
+        Pointer(true) => "isize",
+        Pointer(false) => "usize",
+        Fixed(I8, true) => "i8",
+        Fixed(I8, false) => "u8",
+        Fixed(I16, true) => "i16",
+        Fixed(I16, false) => "u16",
+        Fixed(I32, true) => "i32",
+        Fixed(I32, false) => "u32",
+        Fixed(I64, true) => "i64",
+        Fixed(I64, false) => "u64",
+        Fixed(I128, true) => "i128",
+        Fixed(I128, false) => "u128",
+    }
+    .to_owned()
+}
diff --git a/src/librustdoc/json/mod.rs b/src/librustdoc/json/mod.rs
index 600a4b429f3..760e48baffa 100644
--- a/src/librustdoc/json/mod.rs
+++ b/src/librustdoc/json/mod.rs
@@ -133,7 +133,7 @@ fn target(sess: &rustc_session::Session) -> types::Target {
     let feature_stability: FxHashMap<&str, Stability> = sess
         .target
         .rust_target_features()
-        .into_iter()
+        .iter()
         .copied()
         .map(|(name, stability, _)| (name, stability))
         .collect();
@@ -143,7 +143,7 @@ fn target(sess: &rustc_session::Session) -> types::Target {
         target_features: sess
             .target
             .rust_target_features()
-            .into_iter()
+            .iter()
             .copied()
             .filter(|(_, stability, _)| {
                 // Describe only target features which the user can toggle
@@ -157,7 +157,7 @@ fn target(sess: &rustc_session::Session) -> types::Target {
                         _ => None,
                     },
                     implies_features: implied_features
-                        .into_iter()
+                        .iter()
                         .copied()
                         .filter(|name| {
                             // Imply only target features which the user can toggle
diff --git a/src/librustdoc/passes/collect_intra_doc_links.rs b/src/librustdoc/passes/collect_intra_doc_links.rs
index ca6f67eb6df..5a9aa2a94c8 100644
--- a/src/librustdoc/passes/collect_intra_doc_links.rs
+++ b/src/librustdoc/passes/collect_intra_doc_links.rs
@@ -274,7 +274,7 @@ impl From<DiagnosticInfo<'_>> for OwnedDiagnosticInfo {
 }
 
 impl OwnedDiagnosticInfo {
-    pub(crate) fn into_info(&self) -> DiagnosticInfo<'_> {
+    pub(crate) fn as_info(&self) -> DiagnosticInfo<'_> {
         DiagnosticInfo {
             item: &self.item,
             ori_link: &self.ori_link,
@@ -1177,7 +1177,7 @@ impl LinkCollector<'_, '_> {
                     // Primitive types are always valid.
                     Res::Primitive(_) => true,
                 });
-                let diag_info = info.diag_info.into_info();
+                let diag_info = info.diag_info.as_info();
                 match info.resolved.len() {
                     1 => {
                         let (res, fragment) = info.resolved.pop().unwrap();
@@ -1243,17 +1243,16 @@ impl LinkCollector<'_, '_> {
             disambiguator,
             None | Some(Disambiguator::Namespace(Namespace::TypeNS) | Disambiguator::Primitive)
         ) && !matches!(res, Res::Primitive(_))
+            && let Some(prim) = resolve_primitive(path_str, TypeNS)
         {
-            if let Some(prim) = resolve_primitive(path_str, TypeNS) {
-                // `prim@char`
-                if matches!(disambiguator, Some(Disambiguator::Primitive)) {
-                    res = prim;
-                } else {
-                    // `[char]` when a `char` module is in scope
-                    let candidates = &[(res, res.def_id(self.cx.tcx)), (prim, None)];
-                    ambiguity_error(self.cx, &diag_info, path_str, candidates, true);
-                    return None;
-                }
+            // `prim@char`
+            if matches!(disambiguator, Some(Disambiguator::Primitive)) {
+                res = prim;
+            } else {
+                // `[char]` when a `char` module is in scope
+                let candidates = &[(res, res.def_id(self.cx.tcx)), (prim, None)];
+                ambiguity_error(self.cx, &diag_info, path_str, candidates, true);
+                return None;
             }
         }
 
@@ -2233,7 +2232,7 @@ fn ambiguity_error(
     // proc macro can exist in multiple namespaces at once, so we need to compare `DefIds`
     //  to remove the candidate in the fn namespace.
     let mut possible_proc_macro_id = None;
-    let is_proc_macro_crate = cx.tcx.crate_types() == &[CrateType::ProcMacro];
+    let is_proc_macro_crate = cx.tcx.crate_types() == [CrateType::ProcMacro];
     let mut kinds = candidates
         .iter()
         .map(|(res, def_id)| {
diff --git a/src/librustdoc/passes/lint/redundant_explicit_links.rs b/src/librustdoc/passes/lint/redundant_explicit_links.rs
index 5757b6a9740..e69cf87f957 100644
--- a/src/librustdoc/passes/lint/redundant_explicit_links.rs
+++ b/src/librustdoc/passes/lint/redundant_explicit_links.rs
@@ -93,14 +93,14 @@ fn check_redundant_explicit_link<'md>(
         if let Event::Start(Tag::Link { link_type, dest_url, .. }) = event {
             let link_data = collect_link_data(&mut offset_iter);
 
-            if let Some(resolvable_link) = link_data.resolvable_link.as_ref() {
-                if &link_data.display_link.replace('`', "") != resolvable_link {
-                    // Skips if display link does not match to actual
-                    // resolvable link, usually happens if display link
-                    // has several segments, e.g.
-                    // [this is just an `Option`](Option)
-                    continue;
-                }
+            if let Some(resolvable_link) = link_data.resolvable_link.as_ref()
+                && &link_data.display_link.replace('`', "") != resolvable_link
+            {
+                // Skips if display link does not match to actual
+                // resolvable link, usually happens if display link
+                // has several segments, e.g.
+                // [this is just an `Option`](Option)
+                continue;
             }
 
             let explicit_link = dest_url.to_string();
diff --git a/src/librustdoc/passes/strip_aliased_non_local.rs b/src/librustdoc/passes/strip_aliased_non_local.rs
index b53e3b4e3d7..bb13308e6c2 100644
--- a/src/librustdoc/passes/strip_aliased_non_local.rs
+++ b/src/librustdoc/passes/strip_aliased_non_local.rs
@@ -47,13 +47,11 @@ impl DocFolder for NonLocalStripper<'_> {
         // FIXME(#125009): Not-local should probably consider same Cargo workspace
         if let Some(def_id) = i.def_id()
             && !def_id.is_local()
-        {
-            if i.is_doc_hidden()
+            && (i.is_doc_hidden()
                 // Default to *not* stripping items with inherited visibility.
-                || i.visibility(self.tcx).is_some_and(|viz| viz != Visibility::Public)
-            {
-                return Some(strip_item(i));
-            }
+                || i.visibility(self.tcx).is_some_and(|viz| viz != Visibility::Public))
+        {
+            return Some(strip_item(i));
         }
 
         Some(self.fold_item_recur(i))
diff --git a/src/llvm-project b/src/llvm-project
-Subproject d3c793b025645a4565ac59aceb30d2d116ff1a4
+Subproject e8a2ffcf322f45b8dce82c65ab27a3e2430a6b5
diff --git a/src/rustdoc-json-types/lib.rs b/src/rustdoc-json-types/lib.rs
index 0e72ddd9db1..6235b0e8576 100644
--- a/src/rustdoc-json-types/lib.rs
+++ b/src/rustdoc-json-types/lib.rs
@@ -37,8 +37,8 @@ pub type FxHashMap<K, V> = HashMap<K, V>; // re-export for use in src/librustdoc
 // will instead cause conflicts. See #94591 for more. (This paragraph and the "Latest feature" line
 // are deliberately not in a doc comment, because they need not be in public docs.)
 //
-// Latest feature: Pretty printing of no_mangle attributes changed
-pub const FORMAT_VERSION: u32 = 53;
+// Latest feature: Structured Attributes
+pub const FORMAT_VERSION: u32 = 54;
 
 /// The root of the emitted JSON blob.
 ///
@@ -195,13 +195,94 @@ pub struct Item {
     /// - `#[repr(C)]` and other reprs also appear as themselves,
     ///   though potentially with a different order: e.g. `repr(i8, C)` may become `repr(C, i8)`.
     ///   Multiple repr attributes on the same item may be combined into an equivalent single attr.
-    pub attrs: Vec<String>,
+    pub attrs: Vec<Attribute>,
     /// Information about the item’s deprecation, if present.
     pub deprecation: Option<Deprecation>,
     /// The type-specific fields describing this item.
     pub inner: ItemEnum,
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+/// An attribute, e.g. `#[repr(C)]`
+///
+/// This doesn't include:
+/// - `#[doc = "Doc Comment"]` or `/// Doc comment`. These are in [`Item::docs`] instead.
+/// - `#[deprecated]`. These are in [`Item::deprecation`] instead.
+pub enum Attribute {
+    /// `#[non_exhaustive]`
+    NonExhaustive,
+
+    /// `#[must_use]`
+    MustUse { reason: Option<String> },
+
+    /// `#[export_name = "name"]`
+    ExportName(String),
+
+    /// `#[link_section = "name"]`
+    LinkSection(String),
+
+    /// `#[automatically_derived]`
+    AutomaticallyDerived,
+
+    /// `#[repr]`
+    Repr(AttributeRepr),
+
+    /// `#[no_mangle]`
+    NoMangle,
+
+    /// #[target_feature(enable = "feature1", enable = "feature2")]
+    TargetFeature { enable: Vec<String> },
+
+    /// Something else.
+    ///
+    /// Things here are explicitly *not* covered by the [`FORMAT_VERSION`]
+    /// constant, and may change without bumping the format version.
+    ///
+    /// As an implementation detail, this is currently either:
+    /// 1. A HIR debug printing, like `"#[attr = Optimize(Speed)]"`
+    /// 2. The attribute as it appears in source form, like
+    ///    `"#[optimize(speed)]"`.
+    Other(String),
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+/// The contents of a `#[repr(...)]` attribute.
+///
+/// Used in [`Attribute::Repr`].
+pub struct AttributeRepr {
+    /// The representation, e.g. `#[repr(C)]`, `#[repr(transparent)]`
+    pub kind: ReprKind,
+
+    /// Alignment in bytes, if explicitly specified by `#[repr(align(...)]`.
+    pub align: Option<u64>,
+    /// Alignment in bytes, if explicitly specified by `#[repr(packed(...)]]`.
+    pub packed: Option<u64>,
+
+    /// The integer type for an enum descriminant, if explicitly specified.
+    ///
+    /// e.g. `"i32"`, for `#[repr(C, i32)]`
+    pub int: Option<String>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+/// The kind of `#[repr]`.
+///
+/// See [AttributeRepr::kind]`.
+pub enum ReprKind {
+    /// `#[repr(Rust)]`
+    ///
+    /// Also the default.
+    Rust,
+    /// `#[repr(C)]`
+    C,
+    /// `#[repr(transparent)]
+    Transparent,
+    /// `#[repr(simd)]`
+    Simd,
+}
+
 /// A range of source code.
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
 pub struct Span {
@@ -1343,7 +1424,7 @@ pub struct Static {
 
     /// Is the static `unsafe`?
     ///
-    /// This is only true if it's in an `extern` block, and not explicity marked
+    /// This is only true if it's in an `extern` block, and not explicitly marked
     /// as `safe`.
     ///
     /// ```rust
diff --git a/src/tools/cargo b/src/tools/cargo
-Subproject eabb4cd923deb73e714f7ad3f5234d68ca284db
+Subproject 6833aa715d724437dc1247d0166afe314ab6854
diff --git a/src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs b/src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs
index 07df893ae3c..a9d3015ce5c 100644
--- a/src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs
+++ b/src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs
@@ -306,7 +306,7 @@ impl<'tcx> LateLintPass<'tcx> for ArbitrarySourceItemOrdering {
                     cur_f = Some(field);
                 }
             },
-            ItemKind::Trait(is_auto, _safety, _ident, _generics, _generic_bounds, item_ref)
+            ItemKind::Trait(_constness, is_auto, _safety, _ident, _generics, _generic_bounds, item_ref)
                 if self.enable_ordering_for_trait && *is_auto == IsAuto::No =>
             {
                 let mut cur_t: Option<(TraitItemId, Ident)> = None;
diff --git a/src/tools/clippy/clippy_lints/src/doc/mod.rs b/src/tools/clippy/clippy_lints/src/doc/mod.rs
index 2bf52216b83..22b781b8929 100644
--- a/src/tools/clippy/clippy_lints/src/doc/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/doc/mod.rs
@@ -740,7 +740,7 @@ impl<'tcx> LateLintPass<'tcx> for Documentation {
                             );
                         }
                     },
-                    ItemKind::Trait(_, unsafety, ..) => match (headers.safety, unsafety) {
+                    ItemKind::Trait(_, _, unsafety, ..) => match (headers.safety, unsafety) {
                         (false, Safety::Unsafe) => span_lint(
                             cx,
                             MISSING_SAFETY_DOC,
diff --git a/src/tools/clippy/clippy_lints/src/len_zero.rs b/src/tools/clippy/clippy_lints/src/len_zero.rs
index d32017a8b41..1bf03480c82 100644
--- a/src/tools/clippy/clippy_lints/src/len_zero.rs
+++ b/src/tools/clippy/clippy_lints/src/len_zero.rs
@@ -125,7 +125,7 @@ declare_lint_pass!(LenZero => [LEN_ZERO, LEN_WITHOUT_IS_EMPTY, COMPARISON_TO_EMP
 
 impl<'tcx> LateLintPass<'tcx> for LenZero {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
-        if let ItemKind::Trait(_, _, ident, _, _, trait_items) = item.kind
+        if let ItemKind::Trait(_, _, _, ident, _, _, trait_items) = item.kind
             && !item.span.from_expansion()
         {
             check_trait_items(cx, item, ident, trait_items);
diff --git a/src/tools/clippy/clippy_lints/src/methods/from_iter_instead_of_collect.rs b/src/tools/clippy/clippy_lints/src/methods/from_iter_instead_of_collect.rs
index 045363058d1..d664eaaac70 100644
--- a/src/tools/clippy/clippy_lints/src/methods/from_iter_instead_of_collect.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/from_iter_instead_of_collect.rs
@@ -4,6 +4,7 @@ use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::ty::implements_trait;
 use clippy_utils::{is_path_diagnostic_item, sugg};
+use rustc_ast::join_path_idents;
 use rustc_errors::Applicability;
 use rustc_hir::def::Res;
 use rustc_hir::{self as hir, Expr, ExprKind, GenericArg, QPath, TyKind};
@@ -47,7 +48,7 @@ fn build_full_type(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, app: &mut Applica
         && let QPath::Resolved(None, ty_path) = &ty_qpath
         && let Res::Def(_, ty_did) = ty_path.res
     {
-        let mut ty_str = itertools::join(ty_path.segments.iter().map(|s| s.ident), "::");
+        let mut ty_str = join_path_idents(ty_path.segments.iter().map(|seg| seg.ident));
         let mut first = true;
         let mut append = |arg: &str| {
             write!(&mut ty_str, "{}{arg}", [", ", "<"][usize::from(first)]).unwrap();
diff --git a/src/tools/clippy/clippy_lints/src/missing_inline.rs b/src/tools/clippy/clippy_lints/src/missing_inline.rs
index 329f7193437..c4a3d10299b 100644
--- a/src/tools/clippy/clippy_lints/src/missing_inline.rs
+++ b/src/tools/clippy/clippy_lints/src/missing_inline.rs
@@ -101,7 +101,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingInline {
                 let attrs = cx.tcx.hir_attrs(it.hir_id());
                 check_missing_inline_attrs(cx, attrs, it.span, desc);
             },
-            hir::ItemKind::Trait(ref _is_auto, ref _unsafe, _ident, _generics, _bounds, trait_items) => {
+            hir::ItemKind::Trait(ref _constness, ref _is_auto, ref _unsafe, _ident, _generics, _bounds, trait_items) => {
                 // note: we need to check if the trait is exported so we can't use
                 // `LateLintPass::check_trait_item` here.
                 for &tit in trait_items {
diff --git a/src/tools/clippy/clippy_lints/src/std_instead_of_core.rs b/src/tools/clippy/clippy_lints/src/std_instead_of_core.rs
index cf70e883bd0..216f168471e 100644
--- a/src/tools/clippy/clippy_lints/src/std_instead_of_core.rs
+++ b/src/tools/clippy/clippy_lints/src/std_instead_of_core.rs
@@ -249,7 +249,7 @@ fn is_stable(cx: &LateContext<'_>, mut def_id: DefId, msrv: Msrv) -> bool {
             let stable = match since {
                 StableSince::Version(v) => msrv.meets(cx, v),
                 StableSince::Current => msrv.current(cx).is_none(),
-                StableSince::Err => false,
+                StableSince::Err(_) => false,
             };
 
             if !stable {
diff --git a/src/tools/clippy/clippy_lints/src/trait_bounds.rs b/src/tools/clippy/clippy_lints/src/trait_bounds.rs
index 45e54302e32..9182a55081f 100644
--- a/src/tools/clippy/clippy_lints/src/trait_bounds.rs
+++ b/src/tools/clippy/clippy_lints/src/trait_bounds.rs
@@ -112,7 +112,7 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
         // special handling for self trait bounds as these are not considered generics
         // ie. trait Foo: Display {}
         if let Item {
-            kind: ItemKind::Trait(_, _, _, _, bounds, ..),
+            kind: ItemKind::Trait(_, _, _, _, _, bounds, ..),
             ..
         } = item
         {
@@ -133,7 +133,7 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
                     ..
                 }) = segments.first()
                 && let Some(Node::Item(Item {
-                    kind: ItemKind::Trait(_, _, _, _, self_bounds, _),
+                    kind: ItemKind::Trait(_, _, _, _, _, self_bounds, _),
                     ..
                 })) = cx.tcx.hir_get_if_local(*def_id)
             {
diff --git a/src/tools/clippy/clippy_lints/src/upper_case_acronyms.rs b/src/tools/clippy/clippy_lints/src/upper_case_acronyms.rs
index 02281b9e922..944cd91a7fd 100644
--- a/src/tools/clippy/clippy_lints/src/upper_case_acronyms.rs
+++ b/src/tools/clippy/clippy_lints/src/upper_case_acronyms.rs
@@ -131,7 +131,7 @@ impl LateLintPass<'_> for UpperCaseAcronyms {
             return;
         }
         match it.kind {
-            ItemKind::TyAlias(ident, ..) | ItemKind::Struct(ident, ..) | ItemKind::Trait(_, _, ident, ..) => {
+            ItemKind::TyAlias(ident, ..) | ItemKind::Struct(ident, ..) | ItemKind::Trait(_, _, _, ident, ..) => {
                 check_ident(cx, &ident, it.hir_id(), self.upper_case_acronyms_aggressive);
             },
             ItemKind::Enum(ident, _, ref enumdef) => {
diff --git a/src/tools/clippy/clippy_utils/src/ast_utils/mod.rs b/src/tools/clippy/clippy_utils/src/ast_utils/mod.rs
index 42254ec8e92..96f0273c439 100644
--- a/src/tools/clippy/clippy_utils/src/ast_utils/mod.rs
+++ b/src/tools/clippy/clippy_utils/src/ast_utils/mod.rs
@@ -444,6 +444,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
         },
         (
             Trait(box ast::Trait {
+                constness: lc,
                 is_auto: la,
                 safety: lu,
                 ident: li,
@@ -452,6 +453,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 items: lis,
             }),
             Trait(box ast::Trait {
+                constness: rc,
                 is_auto: ra,
                 safety: ru,
                 ident: ri,
@@ -460,7 +462,8 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 items: ris,
             }),
         ) => {
-            la == ra
+            matches!(lc, ast::Const::No) == matches!(rc, ast::Const::No)
+                && la == ra
                 && matches!(lu, Safety::Default) == matches!(ru, Safety::Default)
                 && eq_id(*li, *ri)
                 && eq_generics(lg, rg)
diff --git a/src/tools/clippy/clippy_utils/src/check_proc_macro.rs b/src/tools/clippy/clippy_utils/src/check_proc_macro.rs
index ce61fffe0de..dc31ed08fb7 100644
--- a/src/tools/clippy/clippy_utils/src/check_proc_macro.rs
+++ b/src/tools/clippy/clippy_utils/src/check_proc_macro.rs
@@ -252,11 +252,11 @@ fn item_search_pat(item: &Item<'_>) -> (Pat, Pat) {
         ItemKind::Struct(_, _, VariantData::Struct { .. }) => (Pat::Str("struct"), Pat::Str("}")),
         ItemKind::Struct(..) => (Pat::Str("struct"), Pat::Str(";")),
         ItemKind::Union(..) => (Pat::Str("union"), Pat::Str("}")),
-        ItemKind::Trait(_, Safety::Unsafe, ..)
+        ItemKind::Trait(_, _, Safety::Unsafe, ..)
         | ItemKind::Impl(Impl {
             safety: Safety::Unsafe, ..
         }) => (Pat::Str("unsafe"), Pat::Str("}")),
-        ItemKind::Trait(IsAuto::Yes, ..) => (Pat::Str("auto"), Pat::Str("}")),
+        ItemKind::Trait(_, IsAuto::Yes, ..) => (Pat::Str("auto"), Pat::Str("}")),
         ItemKind::Trait(..) => (Pat::Str("trait"), Pat::Str("}")),
         ItemKind::Impl(_) => (Pat::Str("impl"), Pat::Str("}")),
         _ => return (Pat::Str(""), Pat::Str("")),
diff --git a/src/tools/clippy/clippy_utils/src/lib.rs b/src/tools/clippy/clippy_utils/src/lib.rs
index ad8c816e204..ff1ee663f9b 100644
--- a/src/tools/clippy/clippy_utils/src/lib.rs
+++ b/src/tools/clippy/clippy_utils/src/lib.rs
@@ -89,6 +89,7 @@ use std::sync::{Mutex, MutexGuard, OnceLock};
 
 use itertools::Itertools;
 use rustc_abi::Integer;
+use rustc_ast::join_path_syms;
 use rustc_ast::ast::{self, LitKind, RangeLimits};
 use rustc_attr_data_structures::{AttributeKind, find_attr};
 use rustc_data_structures::fx::FxHashMap;
@@ -3245,8 +3246,8 @@ fn maybe_get_relative_path(from: &DefPath, to: &DefPath, max_super: usize) -> St
                 // a::b::c  ::d::sym refers to
                 // e::f::sym:: ::
                 // result should be super::super::super::super::e::f
-                if let DefPathData::TypeNs(s) = l {
-                    path.push(s.to_string());
+                if let DefPathData::TypeNs(sym) = l {
+                    path.push(sym);
                 }
                 if let DefPathData::TypeNs(_) = r {
                     go_up_by += 1;
@@ -3256,7 +3257,7 @@ fn maybe_get_relative_path(from: &DefPath, to: &DefPath, max_super: usize) -> St
             // a::b::sym:: ::    refers to
             // c::d::e  ::f::sym
             // when looking at `f`
-            Left(DefPathData::TypeNs(sym)) => path.push(sym.to_string()),
+            Left(DefPathData::TypeNs(sym)) => path.push(sym),
             // consider:
             // a::b::c  ::d::sym refers to
             // e::f::sym:: ::
@@ -3268,17 +3269,17 @@ fn maybe_get_relative_path(from: &DefPath, to: &DefPath, max_super: usize) -> St
 
     if go_up_by > max_super {
         // `super` chain would be too long, just use the absolute path instead
-        once(String::from("crate"))
-            .chain(to.data.iter().filter_map(|el| {
+        join_path_syms(
+            once(kw::Crate).chain(to.data.iter().filter_map(|el| {
                 if let DefPathData::TypeNs(sym) = el.data {
-                    Some(sym.to_string())
+                    Some(sym)
                 } else {
                     None
                 }
             }))
-            .join("::")
+        )
     } else {
-        repeat_n(String::from("super"), go_up_by).chain(path).join("::")
+        join_path_syms(repeat_n(kw::Super, go_up_by).chain(path))
     }
 }
 
diff --git a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
index 942c71ac33b..b3356450d38 100644
--- a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
+++ b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
@@ -432,7 +432,7 @@ pub fn is_stable_const_fn(cx: &LateContext<'_>, def_id: DefId, msrv: Msrv) -> bo
                     let const_stab_rust_version = match since {
                         StableSince::Version(version) => version,
                         StableSince::Current => RustcVersion::CURRENT,
-                        StableSince::Err => return false,
+                        StableSince::Err(_) => return false,
                     };
 
                     msrv.meets(cx, const_stab_rust_version)
diff --git a/src/tools/clippy/tests/ui/assign_ops.fixed b/src/tools/clippy/tests/ui/assign_ops.fixed
index 99beea850a2..eee61f949e7 100644
--- a/src/tools/clippy/tests/ui/assign_ops.fixed
+++ b/src/tools/clippy/tests/ui/assign_ops.fixed
@@ -84,8 +84,7 @@ mod issue14871 {
         const ONE: Self;
     }
 
-    #[const_trait]
-    pub trait NumberConstants {
+    pub const trait NumberConstants {
         fn constant(value: usize) -> Self;
     }
 
diff --git a/src/tools/clippy/tests/ui/assign_ops.rs b/src/tools/clippy/tests/ui/assign_ops.rs
index 900d5ad38e0..13ffcee0a3c 100644
--- a/src/tools/clippy/tests/ui/assign_ops.rs
+++ b/src/tools/clippy/tests/ui/assign_ops.rs
@@ -84,8 +84,7 @@ mod issue14871 {
         const ONE: Self;
     }
 
-    #[const_trait]
-    pub trait NumberConstants {
+    pub const trait NumberConstants {
         fn constant(value: usize) -> Self;
     }
 
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.fixed b/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.fixed
index f1d5579a723..c113c1caaa6 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.fixed
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.fixed
@@ -3,8 +3,7 @@
 
 // Reduced test case from https://github.com/rust-lang/rust-clippy/issues/14658
 
-#[const_trait]
-trait ConstTrait {
+const trait ConstTrait {
     fn method(self);
 }
 
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.rs b/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.rs
index d495759526d..69248bc52d5 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.rs
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.rs
@@ -3,8 +3,7 @@
 
 // Reduced test case from https://github.com/rust-lang/rust-clippy/issues/14658
 
-#[const_trait]
-trait ConstTrait {
+const trait ConstTrait {
     fn method(self);
 }
 
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.stderr b/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.stderr
index b994b88fac6..7ea009cfc9b 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.stderr
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.stderr
@@ -1,5 +1,5 @@
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/const_trait.rs:24:1
+  --> tests/ui/missing_const_for_fn/const_trait.rs:23:1
    |
 LL | / fn can_be_const() {
 LL | |     0u64.method();
diff --git a/src/tools/clippy/tests/ui/ptr_arg.rs b/src/tools/clippy/tests/ui/ptr_arg.rs
index 65f3f05d6cb..578641e910d 100644
--- a/src/tools/clippy/tests/ui/ptr_arg.rs
+++ b/src/tools/clippy/tests/ui/ptr_arg.rs
@@ -312,7 +312,7 @@ mod issue_9218 {
 
     // Inferred to be `&'a str`, afaik.
     fn cow_good_ret_ty<'a>(input: &'a Cow<'a, str>) -> &str {
-        //~^ ERROR: lifetime flowing from input to output with different syntax
+        //~^ ERROR: eliding a lifetime that's named elsewhere is confusing
         todo!()
     }
 }
diff --git a/src/tools/clippy/tests/ui/ptr_arg.stderr b/src/tools/clippy/tests/ui/ptr_arg.stderr
index 600343754e1..fd9ceddfe11 100644
--- a/src/tools/clippy/tests/ui/ptr_arg.stderr
+++ b/src/tools/clippy/tests/ui/ptr_arg.stderr
@@ -231,18 +231,19 @@ error: writing `&String` instead of `&str` involves a new object where a slice w
 LL |     fn good(v1: &String, v2: &String) {
    |                              ^^^^^^^ help: change this to: `&str`
 
-error: lifetime flowing from input to output with different syntax can be confusing
+error: eliding a lifetime that's named elsewhere is confusing
   --> tests/ui/ptr_arg.rs:314:36
    |
 LL |     fn cow_good_ret_ty<'a>(input: &'a Cow<'a, str>) -> &str {
-   |                                    ^^     ^^           ---- the lifetime gets resolved as `'a`
+   |                                    ^^     ^^           ---- the same lifetime is elided here
    |                                    |      |
-   |                                    |      these lifetimes flow to the output
-   |                                    these lifetimes flow to the output
+   |                                    |      the lifetime is named here
+   |                                    the lifetime is named here
    |
+   = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
    = note: `-D mismatched-lifetime-syntaxes` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(mismatched_lifetime_syntaxes)]`
-help: one option is to consistently use `'a`
+help: consistently use `'a`
    |
 LL |     fn cow_good_ret_ty<'a>(input: &'a Cow<'a, str>) -> &'a str {
    |                                                         ++
diff --git a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.fixed b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.fixed
index cf52ecf2f03..88ba5f810b4 100644
--- a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.fixed
+++ b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.fixed
@@ -167,8 +167,7 @@ where
 }
 
 // #13476
-#[const_trait]
-trait ConstTrait {}
+const trait ConstTrait {}
 const fn const_trait_bounds_good<T: ConstTrait + [const] ConstTrait>() {}
 
 const fn const_trait_bounds_bad<T: [const] ConstTrait>() {}
diff --git a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs
index 955562f08dc..19a4e70e294 100644
--- a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs
+++ b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs
@@ -167,8 +167,7 @@ where
 }
 
 // #13476
-#[const_trait]
-trait ConstTrait {}
+const trait ConstTrait {}
 const fn const_trait_bounds_good<T: ConstTrait + [const] ConstTrait>() {}
 
 const fn const_trait_bounds_bad<T: [const] ConstTrait + [const] ConstTrait>() {}
diff --git a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr
index ab31721ef51..a56a683de97 100644
--- a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr
+++ b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr
@@ -59,19 +59,19 @@ LL | fn bad_trait_object(arg0: &(dyn Any + Send + Send)) {
    |                                 ^^^^^^^^^^^^^^^^^ help: try: `Any + Send`
 
 error: these bounds contain repeated elements
-  --> tests/ui/trait_duplication_in_bounds.rs:174:36
+  --> tests/ui/trait_duplication_in_bounds.rs:173:36
    |
 LL | const fn const_trait_bounds_bad<T: [const] ConstTrait + [const] ConstTrait>() {}
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `[const] ConstTrait`
 
 error: these where clauses contain repeated elements
-  --> tests/ui/trait_duplication_in_bounds.rs:181:8
+  --> tests/ui/trait_duplication_in_bounds.rs:180:8
    |
 LL |     T: IntoIterator<Item = U::Owned> + IntoIterator<Item = U::Owned>,
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `IntoIterator<Item = U::Owned>`
 
 error: these where clauses contain repeated elements
-  --> tests/ui/trait_duplication_in_bounds.rs:203:8
+  --> tests/ui/trait_duplication_in_bounds.rs:202:8
    |
 LL |     T: AssocConstTrait<ASSOC = 0> + AssocConstTrait<ASSOC = 0>,
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `AssocConstTrait<ASSOC = 0>`
diff --git a/src/tools/compiletest/src/common.rs b/src/tools/compiletest/src/common.rs
index 33da1a25db1..12084fa0b15 100644
--- a/src/tools/compiletest/src/common.rs
+++ b/src/tools/compiletest/src/common.rs
@@ -88,11 +88,37 @@ string_enum! {
     }
 }
 
+string_enum! {
+    #[derive(Clone, Copy, PartialEq, Debug, Hash)]
+    pub enum RunResult {
+        Pass => "run-pass",
+        Fail => "run-fail",
+        Crash => "run-crash",
+    }
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, PartialOrd)]
+pub enum RunFailMode {
+    /// Running the program must make it exit with a regular failure exit code
+    /// in the range `1..=127`. If the program is terminated by e.g. a signal
+    /// the test will fail.
+    Fail,
+    /// Running the program must result in a crash, e.g. by `SIGABRT` or
+    /// `SIGSEGV` on Unix or on Windows by having an appropriate NTSTATUS high
+    /// bit in the exit code.
+    Crash,
+    /// Running the program must either fail or crash. Useful for e.g. sanitizer
+    /// tests since some sanitizer implementations exit the process with code 1
+    /// to in the face of memory errors while others abort (crash) the process
+    /// in the face of memory errors.
+    FailOrCrash,
+}
+
 #[derive(Copy, Clone, Debug, PartialEq, PartialOrd)]
 pub enum FailMode {
     Check,
     Build,
-    Run,
+    Run(RunFailMode),
 }
 
 string_enum! {
@@ -149,6 +175,36 @@ pub enum Sanitizer {
     Hwaddress,
 }
 
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum CodegenBackend {
+    Cranelift,
+    Gcc,
+    Llvm,
+}
+
+impl<'a> TryFrom<&'a str> for CodegenBackend {
+    type Error = &'static str;
+
+    fn try_from(value: &'a str) -> Result<Self, Self::Error> {
+        match value.to_lowercase().as_str() {
+            "cranelift" => Ok(Self::Cranelift),
+            "gcc" => Ok(Self::Gcc),
+            "llvm" => Ok(Self::Llvm),
+            _ => Err("unknown backend"),
+        }
+    }
+}
+
+impl CodegenBackend {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            Self::Cranelift => "cranelift",
+            Self::Gcc => "gcc",
+            Self::Llvm => "llvm",
+        }
+    }
+}
+
 /// Configuration for `compiletest` *per invocation*.
 ///
 /// In terms of `bootstrap`, this means that `./x test tests/ui tests/run-make` actually correspond
@@ -625,6 +681,9 @@ pub struct Config {
     /// need `core` stubs in cross-compilation scenarios that do not otherwise want/need to
     /// `-Zbuild-std`. Used in e.g. ABI tests.
     pub minicore_path: Utf8PathBuf,
+
+    /// Current codegen backend used.
+    pub codegen_backend: CodegenBackend,
 }
 
 impl Config {
@@ -727,6 +786,7 @@ impl Config {
             profiler_runtime: Default::default(),
             diff_command: Default::default(),
             minicore_path: Default::default(),
+            codegen_backend: CodegenBackend::Llvm,
         }
     }
 
diff --git a/src/tools/compiletest/src/directives.rs b/src/tools/compiletest/src/directives.rs
index 6bf968a3132..1397c87ab07 100644
--- a/src/tools/compiletest/src/directives.rs
+++ b/src/tools/compiletest/src/directives.rs
@@ -9,7 +9,7 @@ use camino::{Utf8Path, Utf8PathBuf};
 use semver::Version;
 use tracing::*;
 
-use crate::common::{Config, Debugger, FailMode, PassMode, TestMode};
+use crate::common::{CodegenBackend, Config, Debugger, FailMode, PassMode, RunFailMode, TestMode};
 use crate::debuggers::{extract_cdb_version, extract_gdb_version};
 use crate::directives::auxiliary::{AuxProps, parse_and_update_aux};
 use crate::directives::needs::CachedNeedsConditions;
@@ -654,7 +654,13 @@ impl TestProps {
             Some(FailMode::Build)
         } else if config.parse_name_directive(ln, "run-fail") {
             check_ui("run");
-            Some(FailMode::Run)
+            Some(FailMode::Run(RunFailMode::Fail))
+        } else if config.parse_name_directive(ln, "run-crash") {
+            check_ui("run");
+            Some(FailMode::Run(RunFailMode::Crash))
+        } else if config.parse_name_directive(ln, "run-fail-or-crash") {
+            check_ui("run");
+            Some(FailMode::Run(RunFailMode::FailOrCrash))
         } else {
             None
         };
@@ -812,6 +818,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "ignore-arm-unknown-linux-musleabihf",
     "ignore-auxiliary",
     "ignore-avr",
+    "ignore-backends",
     "ignore-beta",
     "ignore-cdb",
     "ignore-compare-mode-next-solver",
@@ -901,6 +908,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "min-llvm-version",
     "min-system-llvm-version",
     "needs-asm-support",
+    "needs-backends",
     "needs-crate-type",
     "needs-deterministic-layouts",
     "needs-dlltool",
@@ -971,6 +979,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "only-mips64",
     "only-msp430",
     "only-msvc",
+    "only-musl",
     "only-nightly",
     "only-nvptx64",
     "only-powerpc",
@@ -1006,7 +1015,9 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "regex-error-pattern",
     "remap-src-base",
     "revisions",
+    "run-crash",
     "run-fail",
+    "run-fail-or-crash",
     "run-flags",
     "run-pass",
     "run-rustfix",
@@ -1660,6 +1671,8 @@ pub(crate) fn make_test_description<R: Read>(
             decision!(cfg::handle_only(config, ln));
             decision!(needs::handle_needs(&cache.needs, config, ln));
             decision!(ignore_llvm(config, path, ln));
+            decision!(ignore_backends(config, path, ln));
+            decision!(needs_backends(config, path, ln));
             decision!(ignore_cdb(config, ln));
             decision!(ignore_gdb(config, ln));
             decision!(ignore_lldb(config, ln));
@@ -1786,6 +1799,49 @@ fn ignore_lldb(config: &Config, line: &str) -> IgnoreDecision {
     IgnoreDecision::Continue
 }
 
+fn ignore_backends(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
+    if let Some(backends_to_ignore) = config.parse_name_value_directive(line, "ignore-backends") {
+        for backend in backends_to_ignore.split_whitespace().map(|backend| {
+            match CodegenBackend::try_from(backend) {
+                Ok(backend) => backend,
+                Err(error) => {
+                    panic!("Invalid ignore-backends value `{backend}` in `{path}`: {error}")
+                }
+            }
+        }) {
+            if config.codegen_backend == backend {
+                return IgnoreDecision::Ignore {
+                    reason: format!("{} backend is marked as ignore", backend.as_str()),
+                };
+            }
+        }
+    }
+    IgnoreDecision::Continue
+}
+
+fn needs_backends(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
+    if let Some(needed_backends) = config.parse_name_value_directive(line, "needs-backends") {
+        if !needed_backends
+            .split_whitespace()
+            .map(|backend| match CodegenBackend::try_from(backend) {
+                Ok(backend) => backend,
+                Err(error) => {
+                    panic!("Invalid needs-backends value `{backend}` in `{path}`: {error}")
+                }
+            })
+            .any(|backend| config.codegen_backend == backend)
+        {
+            return IgnoreDecision::Ignore {
+                reason: format!(
+                    "{} backend is not part of required backends",
+                    config.codegen_backend.as_str()
+                ),
+            };
+        }
+    }
+    IgnoreDecision::Continue
+}
+
 fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
     if let Some(needed_components) =
         config.parse_name_value_directive(line, "needs-llvm-components")
diff --git a/src/tools/compiletest/src/lib.rs b/src/tools/compiletest/src/lib.rs
index f3b3605a120..41bed8ed8a0 100644
--- a/src/tools/compiletest/src/lib.rs
+++ b/src/tools/compiletest/src/lib.rs
@@ -39,7 +39,7 @@ use walkdir::WalkDir;
 
 use self::directives::{EarlyProps, make_test_description};
 use crate::common::{
-    CompareMode, Config, Debugger, PassMode, TestMode, TestPaths, UI_EXTENSIONS,
+    CodegenBackend, CompareMode, Config, Debugger, PassMode, TestMode, TestPaths, UI_EXTENSIONS,
     expected_output_path, output_base_dir, output_relative_path,
 };
 use crate::directives::DirectivesCache;
@@ -203,6 +203,12 @@ pub fn parse_config(args: Vec<String>) -> Config {
             "debugger",
             "only test a specific debugger in debuginfo tests",
             "gdb | lldb | cdb",
+        )
+        .optopt(
+            "",
+            "codegen-backend",
+            "the codegen backend currently used",
+            "CODEGEN BACKEND NAME",
         );
 
     let (argv0, args_) = args.split_first().unwrap();
@@ -264,6 +270,15 @@ pub fn parse_config(args: Vec<String>) -> Config {
             || directives::extract_llvm_version_from_binary(&matches.opt_str("llvm-filecheck")?),
         );
 
+    let codegen_backend = match matches.opt_str("codegen-backend").as_deref() {
+        Some(backend) => match CodegenBackend::try_from(backend) {
+            Ok(backend) => backend,
+            Err(error) => panic!("invalid value `{backend}` for `--codegen-backend`: {error}"),
+        },
+        // By default, it's always llvm.
+        None => CodegenBackend::Llvm,
+    };
+
     let run_ignored = matches.opt_present("ignored");
     let with_rustc_debug_assertions = matches.opt_present("with-rustc-debug-assertions");
     let with_std_debug_assertions = matches.opt_present("with-std-debug-assertions");
@@ -449,6 +464,8 @@ pub fn parse_config(args: Vec<String>) -> Config {
         diff_command: matches.opt_str("compiletest-diff-tool"),
 
         minicore_path: opt_path(matches, "minicore-path"),
+
+        codegen_backend,
     }
 }
 
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index cb8f593c9df..f66d4f98f1f 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -16,8 +16,8 @@ use regex::{Captures, Regex};
 use tracing::*;
 
 use crate::common::{
-    CompareMode, Config, Debugger, FailMode, PassMode, TestMode, TestPaths, TestSuite,
-    UI_EXTENSIONS, UI_FIXED, UI_RUN_STDERR, UI_RUN_STDOUT, UI_STDERR, UI_STDOUT, UI_SVG,
+    CompareMode, Config, Debugger, FailMode, PassMode, RunFailMode, RunResult, TestMode, TestPaths,
+    TestSuite, UI_EXTENSIONS, UI_FIXED, UI_RUN_STDERR, UI_RUN_STDOUT, UI_STDERR, UI_STDOUT, UI_SVG,
     UI_WINDOWS_SVG, expected_output_path, incremental_dir, output_base_dir, output_base_name,
     output_testname_unique,
 };
@@ -282,7 +282,8 @@ impl<'test> TestCx<'test> {
     fn should_run(&self, pm: Option<PassMode>) -> WillExecute {
         let test_should_run = match self.config.mode {
             TestMode::Ui
-                if pm == Some(PassMode::Run) || self.props.fail_mode == Some(FailMode::Run) =>
+                if pm == Some(PassMode::Run)
+                    || matches!(self.props.fail_mode, Some(FailMode::Run(_))) =>
             {
                 true
             }
diff --git a/src/tools/compiletest/src/runtest/ui.rs b/src/tools/compiletest/src/runtest/ui.rs
index f6bc85cd051..0507c2600ae 100644
--- a/src/tools/compiletest/src/runtest/ui.rs
+++ b/src/tools/compiletest/src/runtest/ui.rs
@@ -6,8 +6,8 @@ use rustfix::{Filter, apply_suggestions, get_suggestions_from_json};
 use tracing::debug;
 
 use super::{
-    AllowUnused, Emit, FailMode, LinkToAux, PassMode, TargetLocation, TestCx, TestOutput,
-    Truncated, UI_FIXED, WillExecute,
+    AllowUnused, Emit, FailMode, LinkToAux, PassMode, RunFailMode, RunResult, TargetLocation,
+    TestCx, TestOutput, Truncated, UI_FIXED, WillExecute,
 };
 use crate::json;
 
@@ -140,12 +140,53 @@ impl TestCx<'_> {
                     &proc_res,
                 );
             }
+            let code = proc_res.status.code();
+            let run_result = if proc_res.status.success() {
+                RunResult::Pass
+            } else if code.is_some_and(|c| c >= 1 && c <= 127) {
+                RunResult::Fail
+            } else {
+                RunResult::Crash
+            };
+            // Help users understand why the test failed by including the actual
+            // exit code and actual run result in the failure message.
+            let pass_hint = format!("code={code:?} so test would pass with `{run_result}`");
             if self.should_run_successfully(pm) {
-                if !proc_res.status.success() {
-                    self.fatal_proc_rec("test run failed!", &proc_res);
+                if run_result != RunResult::Pass {
+                    self.fatal_proc_rec(
+                        &format!("test did not exit with success! {pass_hint}"),
+                        &proc_res,
+                    );
+                }
+            } else if self.props.fail_mode == Some(FailMode::Run(RunFailMode::Fail)) {
+                // If the test is marked as `run-fail` but do not support
+                // unwinding we allow it to crash, since a panic will trigger an
+                // abort (crash) instead of unwind (exit with code 101).
+                let crash_ok = !self.config.can_unwind();
+                if run_result != RunResult::Fail && !(crash_ok && run_result == RunResult::Crash) {
+                    let err = if crash_ok {
+                        format!(
+                            "test did not exit with failure or crash (`{}` can't unwind)! {pass_hint}",
+                            self.config.target
+                        )
+                    } else {
+                        format!("test did not exit with failure! {pass_hint}")
+                    };
+                    self.fatal_proc_rec(&err, &proc_res);
                 }
-            } else if proc_res.status.success() {
-                self.fatal_proc_rec("test run succeeded!", &proc_res);
+            } else if self.props.fail_mode == Some(FailMode::Run(RunFailMode::Crash)) {
+                if run_result != RunResult::Crash {
+                    self.fatal_proc_rec(&format!("test did not crash! {pass_hint}"), &proc_res);
+                }
+            } else if self.props.fail_mode == Some(FailMode::Run(RunFailMode::FailOrCrash)) {
+                if run_result != RunResult::Fail && run_result != RunResult::Crash {
+                    self.fatal_proc_rec(
+                        &format!("test did not exit with failure or crash! {pass_hint}"),
+                        &proc_res,
+                    );
+                }
+            } else {
+                unreachable!("run_ui_test() must not be called if the test should not run");
             }
 
             self.get_output(&proc_res)
diff --git a/src/tools/lint-docs/Cargo.toml b/src/tools/lint-docs/Cargo.toml
index e914a2df2ba..6e1ab84ed18 100644
--- a/src/tools/lint-docs/Cargo.toml
+++ b/src/tools/lint-docs/Cargo.toml
@@ -7,7 +7,7 @@ description = "A script to extract the lint documentation for the rustc book."
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-rustc-literal-escaper = "0.0.4"
+rustc-literal-escaper = "0.0.5"
 serde_json = "1.0.57"
 tempfile = "3.1.0"
 walkdir = "2.3.1"
diff --git a/src/tools/miri/README.md b/src/tools/miri/README.md
index b05acff72b5..7816ce1ac56 100644
--- a/src/tools/miri/README.md
+++ b/src/tools/miri/README.md
@@ -342,9 +342,9 @@ environment variable. We first document the most relevant and most commonly used
   is enabled (the default), this is also used to emulate system entropy. The default seed is 0. You
   can increase test coverage by running Miri multiple times with different seeds.
 * `-Zmiri-strict-provenance` enables [strict
-  provenance](https://github.com/rust-lang/rust/issues/95228) checking in Miri. This means that
-  casting an integer to a pointer will stop execution because the provenance of the pointer
-  cannot be determined.
+  provenance](https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance) checking in
+  Miri. This means that casting an integer to a pointer will stop execution because the provenance
+  of the pointer cannot be determined.
 * `-Zmiri-symbolic-alignment-check` makes the alignment check more strict.  By default, alignment is
   checked by casting the pointer to an integer, and making sure that is a multiple of the alignment.
   This can lead to cases where a program passes the alignment check by pure chance, because things
diff --git a/src/tools/miri/miri-script/Cargo.toml b/src/tools/miri/miri-script/Cargo.toml
index 462a9cc62bf..9240788d6bc 100644
--- a/src/tools/miri/miri-script/Cargo.toml
+++ b/src/tools/miri/miri-script/Cargo.toml
@@ -7,6 +7,7 @@ repository = "https://github.com/rust-lang/miri"
 version = "0.1.0"
 default-run = "miri-script"
 edition = "2024"
+rust-version = "1.85"
 
 [workspace]
 # We make this a workspace root so that cargo does not go looking in ../Cargo.toml for the workspace root.
diff --git a/src/tools/miri/miri-script/src/commands.rs b/src/tools/miri/miri-script/src/commands.rs
index e948beef004..e6ebdf54e38 100644
--- a/src/tools/miri/miri-script/src/commands.rs
+++ b/src/tools/miri/miri-script/src/commands.rs
@@ -702,7 +702,6 @@ impl Command {
         let mut early_flags = Vec::<OsString>::new();
 
         // In `dep` mode, the target is already passed via `MIRI_TEST_TARGET`
-        #[expect(clippy::collapsible_if)] // we need to wait until this is stable
         if !dep {
             if let Some(target) = &target {
                 early_flags.push("--target".into());
@@ -735,7 +734,6 @@ impl Command {
         // Add Miri flags
         let mut cmd = cmd.args(&miri_flags).args(&early_flags).args(&flags);
         // For `--dep` we also need to set the target in the env var.
-        #[expect(clippy::collapsible_if)] // we need to wait until this is stable
         if dep {
             if let Some(target) = &target {
                 cmd = cmd.env("MIRI_TEST_TARGET", target);
diff --git a/src/tools/miri/rust-version b/src/tools/miri/rust-version
index 0130cf13a45..67f27e7aa2c 100644
--- a/src/tools/miri/rust-version
+++ b/src/tools/miri/rust-version
@@ -1 +1 @@
-733b47ea4b1b86216f14ef56e49440c33933f230
+7f2065a4bae1faed5bab928c670964eafbf43b55
diff --git a/src/tools/miri/src/alloc/isolated_alloc.rs b/src/tools/miri/src/alloc/isolated_alloc.rs
index a7bb9b4da75..7b2f1a3eebf 100644
--- a/src/tools/miri/src/alloc/isolated_alloc.rs
+++ b/src/tools/miri/src/alloc/isolated_alloc.rs
@@ -302,23 +302,20 @@ impl IsolatedAlloc {
         }
     }
 
-    /// Returns a vector of page addresses managed by the allocator.
-    pub fn pages(&self) -> Vec<usize> {
-        let mut pages: Vec<usize> =
-            self.page_ptrs.iter().map(|p| p.expose_provenance().get()).collect();
-        for (ptr, size) in self.huge_ptrs.iter() {
-            for i in 0..size / self.page_size {
-                pages.push(ptr.expose_provenance().get().strict_add(i * self.page_size));
-            }
-        }
-        pages
+    /// Returns a list of page addresses managed by the allocator.
+    pub fn pages(&self) -> impl Iterator<Item = usize> {
+        let pages = self.page_ptrs.iter().map(|p| p.expose_provenance().get());
+        pages.chain(self.huge_ptrs.iter().flat_map(|(ptr, size)| {
+            (0..size / self.page_size)
+                .map(|i| ptr.expose_provenance().get().strict_add(i * self.page_size))
+        }))
     }
 
     /// Protects all owned memory as `PROT_NONE`, preventing accesses.
     ///
     /// SAFETY: Accessing memory after this point will result in a segfault
     /// unless it is first unprotected.
-    pub unsafe fn prepare_ffi(&mut self) -> Result<(), nix::errno::Errno> {
+    pub unsafe fn start_ffi(&mut self) -> Result<(), nix::errno::Errno> {
         let prot = mman::ProtFlags::PROT_NONE;
         unsafe { self.mprotect(prot) }
     }
@@ -326,7 +323,7 @@ impl IsolatedAlloc {
     /// Deprotects all owned memory by setting it to RW. Erroring here is very
     /// likely unrecoverable, so it may panic if applying those permissions
     /// fails.
-    pub fn unprep_ffi(&mut self) {
+    pub fn end_ffi(&mut self) {
         let prot = mman::ProtFlags::PROT_READ | mman::ProtFlags::PROT_WRITE;
         unsafe {
             self.mprotect(prot).unwrap();
diff --git a/src/tools/miri/src/alloc_addresses/mod.rs b/src/tools/miri/src/alloc_addresses/mod.rs
index 3cc38fa087c..10339928ac2 100644
--- a/src/tools/miri/src/alloc_addresses/mod.rs
+++ b/src/tools/miri/src/alloc_addresses/mod.rs
@@ -157,7 +157,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                         this.get_alloc_bytes_unchecked_raw(alloc_id)?
                     }
                 }
-                AllocKind::Function | AllocKind::VTable => {
+                AllocKind::Function | AllocKind::Virtual => {
                     // Allocate some dummy memory to get a unique address for this function/vtable.
                     let alloc_bytes = MiriAllocBytes::from_bytes(
                         &[0u8; 1],
diff --git a/src/tools/miri/src/bin/log/tracing_chrome.rs b/src/tools/miri/src/bin/log/tracing_chrome.rs
index 459acea6f0b..5a96633c99e 100644
--- a/src/tools/miri/src/bin/log/tracing_chrome.rs
+++ b/src/tools/miri/src/bin/log/tracing_chrome.rs
@@ -1,8 +1,18 @@
 // SPDX-License-Identifier: MIT
 // SPDX-FileCopyrightText: Copyright (c) 2020 Thoren Paulson
-//! This file is taken unmodified from the following link, except for file attributes and
-//! `extern crate` at the top.
-//! https://github.com/thoren-d/tracing-chrome/blob/7e2625ab4aeeef2f0ef9bde9d6258dd181c04472/src/lib.rs
+//! This file was initially taken from the following link:
+//! <https://github.com/thoren-d/tracing-chrome/blob/7e2625ab4aeeef2f0ef9bde9d6258dd181c04472/src/lib.rs>
+//!
+//! The precise changes that were made to the original file can be found in git history
+//! (`git log -- path/to/tracing_chrome.rs`), but in summary:
+//! - the file attributes were changed and `extern crate` was added at the top
+//! - if a tracing span has a field called "tracing_separate_thread", it will be given a separate
+//! span ID even in [TraceStyle::Threaded] mode, to make it appear on a separate line when viewing
+//! the trace in <https://ui.perfetto.dev>. This is the syntax to trigger this behavior:
+//!   ```rust
+//!   tracing::info_span!("my_span", tracing_separate_thread = tracing::field::Empty, /* ... */)
+//!   ```
+//!
 //! Depending on the tracing-chrome crate from crates.io is unfortunately not possible, since it
 //! depends on `tracing_core` which conflicts with rustc_private's `tracing_core` (meaning it would
 //! not be possible to use the [ChromeLayer] in a context that expects a [Layer] from
@@ -79,14 +89,26 @@ where
 }
 
 /// Decides how traces will be recorded.
+/// Also see <https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview#heading=h.jh64i9l3vwa1>
 #[derive(Default)]
 pub enum TraceStyle {
-    /// Traces will be recorded as a group of threads.
+    /// Traces will be recorded as a group of threads, and all spans on the same thread will appear
+    /// on a single trace line in <https://ui.perfetto.dev>.
     /// In this style, spans should be entered and exited on the same thread.
+    ///
+    /// If a tracing span has a field called "tracing_separate_thread", it will be given a separate
+    /// span ID even in this mode, to make it appear on a separate line when viewing the trace in
+    /// <https://ui.perfetto.dev>. This is the syntax to trigger this behavior:
+    /// ```rust
+    /// tracing::info_span!("my_span", tracing_separate_thread = tracing::field::Empty, /* ... */)
+    /// ```
+    /// [tracing::field::Empty] is used so that other tracing layers (e.g. the logger) will ignore
+    /// the "tracing_separate_thread" argument and not print out anything for it.
     #[default]
     Threaded,
 
-    /// Traces will recorded as a group of asynchronous operations.
+    /// Traces will recorded as a group of asynchronous operations. All spans will be given separate
+    /// span IDs and will appear on separate trace lines in <https://ui.perfetto.dev>.
     Async,
 }
 
@@ -497,31 +519,39 @@ where
         }
     }
 
-    fn get_root_id(span: SpanRef<S>) -> u64 {
-        span.scope()
-            .from_root()
-            .take(1)
-            .next()
-            .unwrap_or(span)
-            .id()
-            .into_u64()
+    fn get_root_id(&self, span: SpanRef<S>) -> Option<u64> {
+        match self.trace_style {
+            TraceStyle::Threaded => {
+                if span.fields().field("tracing_separate_thread").is_some() {
+                    // assign an independent "id" to spans with argument "tracing_separate_thread",
+                    // so they appear a separate trace line in trace visualization tools, see
+                    // https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview#heading=h.jh64i9l3vwa1
+                    Some(span.id().into_u64())
+                } else {
+                    None
+                }
+            },
+            TraceStyle::Async => Some(
+                span.scope()
+                    .from_root()
+                    .take(1)
+                    .next()
+                    .unwrap_or(span)
+                    .id()
+                    .into_u64()
+            ),
+        }
     }
 
     fn enter_span(&self, span: SpanRef<S>, ts: f64) {
         let callsite = self.get_callsite(EventOrSpan::Span(&span));
-        let root_id = match self.trace_style {
-            TraceStyle::Async => Some(ChromeLayer::get_root_id(span)),
-            _ => None,
-        };
+        let root_id = self.get_root_id(span);
         self.send_message(Message::Enter(ts, callsite, root_id));
     }
 
     fn exit_span(&self, span: SpanRef<S>, ts: f64) {
         let callsite = self.get_callsite(EventOrSpan::Span(&span));
-        let root_id = match self.trace_style {
-            TraceStyle::Async => Some(ChromeLayer::get_root_id(span)),
-            _ => None,
-        };
+        let root_id = self.get_root_id(span);
         self.send_message(Message::Exit(ts, callsite, root_id));
     }
 
diff --git a/src/tools/miri/src/bin/miri.rs b/src/tools/miri/src/bin/miri.rs
index e3b579a4ac6..61cebedf081 100644
--- a/src/tools/miri/src/bin/miri.rs
+++ b/src/tools/miri/src/bin/miri.rs
@@ -233,8 +233,6 @@ impl rustc_driver::Callbacks for MiriCompilerCalls {
         } else {
             let return_code = miri::eval_entry(tcx, entry_def_id, entry_type, &config, None)
                 .unwrap_or_else(|| {
-                    //#[cfg(target_os = "linux")]
-                    //miri::native_lib::register_retcode_sv(rustc_driver::EXIT_FAILURE);
                     tcx.dcx().abort_if_errors();
                     rustc_driver::EXIT_FAILURE
                 });
@@ -337,6 +335,9 @@ impl rustc_driver::Callbacks for MiriBeRustCompilerCalls {
 fn exit(exit_code: i32) -> ! {
     // Drop the tracing guard before exiting, so tracing calls are flushed correctly.
     deinit_loggers();
+    // Make sure the supervisor knows about the code code.
+    #[cfg(target_os = "linux")]
+    miri::native_lib::register_retcode_sv(exit_code);
     std::process::exit(exit_code);
 }
 
@@ -355,6 +356,11 @@ fn run_compiler_and_exit(
     args: &[String],
     callbacks: &mut (dyn rustc_driver::Callbacks + Send),
 ) -> ! {
+    // Install the ctrlc handler that sets `rustc_const_eval::CTRL_C_RECEIVED`, even if
+    // MIRI_BE_RUSTC is set. We do this late so that when `native_lib::init_sv` is called,
+    // there are no other threads.
+    rustc_driver::install_ctrlc_handler();
+
     // Invoke compiler, catch any unwinding panics and handle return code.
     let exit_code =
         rustc_driver::catch_with_exit_code(move || rustc_driver::run_compiler(args, callbacks));
@@ -439,10 +445,6 @@ fn main() {
     let args = rustc_driver::catch_fatal_errors(|| rustc_driver::args::raw_args(&early_dcx))
         .unwrap_or_else(|_| std::process::exit(rustc_driver::EXIT_FAILURE));
 
-    // Install the ctrlc handler that sets `rustc_const_eval::CTRL_C_RECEIVED`, even if
-    // MIRI_BE_RUSTC is set.
-    rustc_driver::install_ctrlc_handler();
-
     // If the environment asks us to actually be rustc, then do that.
     if let Some(crate_kind) = env::var_os("MIRI_BE_RUSTC") {
         // Earliest rustc setup.
@@ -750,15 +752,15 @@ fn main() {
 
     debug!("rustc arguments: {:?}", rustc_args);
     debug!("crate arguments: {:?}", miri_config.args);
-    #[cfg(target_os = "linux")]
     if !miri_config.native_lib.is_empty() && miri_config.native_lib_enable_tracing {
-        // FIXME: This should display a diagnostic / warning on error
-        // SAFETY: If any other threads exist at this point (namely for the ctrlc
-        // handler), they will not interact with anything on the main rustc/Miri
-        // thread in an async-signal-unsafe way such as by accessing shared
-        // semaphores, etc.; the handler only calls `sleep()` and `exit()`, which
-        // are async-signal-safe, as is accessing atomics
-        //let _ = unsafe { miri::native_lib::init_sv() };
+        // SAFETY: No other threads are running
+        #[cfg(target_os = "linux")]
+        if unsafe { miri::native_lib::init_sv() }.is_err() {
+            eprintln!(
+                "warning: The native-lib tracer could not be started. Is this an x86 Linux system, and does Miri have permissions to ptrace?\n\
+                Falling back to non-tracing native-lib mode."
+            );
+        }
     }
     run_compiler_and_exit(
         &rustc_args,
diff --git a/src/tools/miri/src/borrow_tracker/mod.rs b/src/tools/miri/src/borrow_tracker/mod.rs
index 36c61053a32..ec6c2c60ca9 100644
--- a/src/tools/miri/src/borrow_tracker/mod.rs
+++ b/src/tools/miri/src/borrow_tracker/mod.rs
@@ -260,6 +260,7 @@ impl GlobalStateInner {
         kind: MemoryKind,
         machine: &MiriMachine<'_>,
     ) -> AllocState {
+        let _span = enter_trace_span!(borrow_tracker::new_allocation, ?id, ?alloc_size, ?kind);
         match self.borrow_tracker_method {
             BorrowTrackerMethod::StackedBorrows =>
                 AllocState::StackedBorrows(Box::new(RefCell::new(Stacks::new_allocation(
@@ -280,6 +281,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         kind: RetagKind,
         val: &ImmTy<'tcx>,
     ) -> InterpResult<'tcx, ImmTy<'tcx>> {
+        let _span = enter_trace_span!(borrow_tracker::retag_ptr_value, ?kind, ?val.layout);
         let this = self.eval_context_mut();
         let method = this.machine.borrow_tracker.as_ref().unwrap().borrow().borrow_tracker_method;
         match method {
@@ -293,6 +295,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         kind: RetagKind,
         place: &PlaceTy<'tcx>,
     ) -> InterpResult<'tcx> {
+        let _span = enter_trace_span!(borrow_tracker::retag_place_contents, ?kind, ?place);
         let this = self.eval_context_mut();
         let method = this.machine.borrow_tracker.as_ref().unwrap().borrow().borrow_tracker_method;
         match method {
@@ -302,6 +305,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     }
 
     fn protect_place(&mut self, place: &MPlaceTy<'tcx>) -> InterpResult<'tcx, MPlaceTy<'tcx>> {
+        let _span = enter_trace_span!(borrow_tracker::protect_place, ?place);
         let this = self.eval_context_mut();
         let method = this.machine.borrow_tracker.as_ref().unwrap().borrow().borrow_tracker_method;
         match method {
@@ -311,6 +315,8 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     }
 
     fn expose_tag(&self, alloc_id: AllocId, tag: BorTag) -> InterpResult<'tcx> {
+        let _span =
+            enter_trace_span!(borrow_tracker::expose_tag, alloc_id = alloc_id.0, tag = tag.0);
         let this = self.eval_context_ref();
         let method = this.machine.borrow_tracker.as_ref().unwrap().borrow().borrow_tracker_method;
         match method {
@@ -354,6 +360,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         &self,
         frame: &Frame<'tcx, Provenance, FrameExtra<'tcx>>,
     ) -> InterpResult<'tcx> {
+        let _span = enter_trace_span!(borrow_tracker::on_stack_pop);
         let this = self.eval_context_ref();
         let borrow_tracker = this.machine.borrow_tracker.as_ref().unwrap();
         // The body of this loop needs `borrow_tracker` immutably
@@ -431,6 +438,7 @@ impl AllocState {
         range: AllocRange,
         machine: &MiriMachine<'tcx>,
     ) -> InterpResult<'tcx> {
+        let _span = enter_trace_span!(borrow_tracker::before_memory_read, alloc_id = alloc_id.0);
         match self {
             AllocState::StackedBorrows(sb) =>
                 sb.borrow_mut().before_memory_read(alloc_id, prov_extra, range, machine),
@@ -452,6 +460,7 @@ impl AllocState {
         range: AllocRange,
         machine: &MiriMachine<'tcx>,
     ) -> InterpResult<'tcx> {
+        let _span = enter_trace_span!(borrow_tracker::before_memory_write, alloc_id = alloc_id.0);
         match self {
             AllocState::StackedBorrows(sb) =>
                 sb.get_mut().before_memory_write(alloc_id, prov_extra, range, machine),
@@ -473,6 +482,8 @@ impl AllocState {
         size: Size,
         machine: &MiriMachine<'tcx>,
     ) -> InterpResult<'tcx> {
+        let _span =
+            enter_trace_span!(borrow_tracker::before_memory_deallocation, alloc_id = alloc_id.0);
         match self {
             AllocState::StackedBorrows(sb) =>
                 sb.get_mut().before_memory_deallocation(alloc_id, prov_extra, size, machine),
@@ -482,6 +493,7 @@ impl AllocState {
     }
 
     pub fn remove_unreachable_tags(&self, tags: &FxHashSet<BorTag>) {
+        let _span = enter_trace_span!(borrow_tracker::remove_unreachable_tags);
         match self {
             AllocState::StackedBorrows(sb) => sb.borrow_mut().remove_unreachable_tags(tags),
             AllocState::TreeBorrows(tb) => tb.borrow_mut().remove_unreachable_tags(tags),
@@ -496,6 +508,11 @@ impl AllocState {
         tag: BorTag,
         alloc_id: AllocId, // diagnostics
     ) -> InterpResult<'tcx> {
+        let _span = enter_trace_span!(
+            borrow_tracker::release_protector,
+            alloc_id = alloc_id.0,
+            tag = tag.0
+        );
         match self {
             AllocState::StackedBorrows(_sb) => interp_ok(()),
             AllocState::TreeBorrows(tb) =>
@@ -506,6 +523,7 @@ impl AllocState {
 
 impl VisitProvenance for AllocState {
     fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
+        let _span = enter_trace_span!(borrow_tracker::visit_provenance);
         match self {
             AllocState::StackedBorrows(sb) => sb.visit_provenance(visit),
             AllocState::TreeBorrows(tb) => tb.visit_provenance(visit),
diff --git a/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs b/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
index b8bcacf7c99..e834fdffdd1 100644
--- a/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
+++ b/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
@@ -30,7 +30,7 @@ pub type AllocState = Stacks;
 #[derive(Clone, Debug)]
 pub struct Stacks {
     // Even reading memory can have effects on the stack, so we need a `RefCell` here.
-    stacks: RangeMap<Stack>,
+    stacks: DedupRangeMap<Stack>,
     /// Stores past operations on this allocation
     history: AllocHistory,
     /// The set of tags that have been exposed inside this allocation.
@@ -468,7 +468,7 @@ impl<'tcx> Stacks {
         let stack = Stack::new(item);
 
         Stacks {
-            stacks: RangeMap::new(size, stack),
+            stacks: DedupRangeMap::new(size, stack),
             history: AllocHistory::new(id, item, machine),
             exposed_tags: FxHashSet::default(),
         }
@@ -650,7 +650,7 @@ trait EvalContextPrivExt<'tcx, 'ecx>: crate::MiriInterpCxExt<'tcx> {
                         dcx.log_protector();
                     }
                 },
-                AllocKind::Function | AllocKind::VTable | AllocKind::Dead => {
+                AllocKind::Function | AllocKind::Virtual | AllocKind::Dead => {
                     // No stacked borrows on these allocations.
                 }
             }
@@ -1021,7 +1021,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 trace!("Stacked Borrows tag {tag:?} exposed in {alloc_id:?}");
                 alloc_extra.borrow_tracker_sb().borrow_mut().exposed_tags.insert(tag);
             }
-            AllocKind::Function | AllocKind::VTable | AllocKind::Dead => {
+            AllocKind::Function | AllocKind::Virtual | AllocKind::Dead => {
                 // No stacked borrows on these allocations.
             }
         }
diff --git a/src/tools/miri/src/borrow_tracker/tree_borrows/mod.rs b/src/tools/miri/src/borrow_tracker/tree_borrows/mod.rs
index a0761cb07a1..aa92f8a8c30 100644
--- a/src/tools/miri/src/borrow_tracker/tree_borrows/mod.rs
+++ b/src/tools/miri/src/borrow_tracker/tree_borrows/mod.rs
@@ -314,7 +314,7 @@ trait EvalContextPrivExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let span = this.machine.current_span();
 
         // Store initial permissions and their corresponding range.
-        let mut perms_map: RangeMap<LocationState> = RangeMap::new(
+        let mut perms_map: DedupRangeMap<LocationState> = DedupRangeMap::new(
             ptr_size,
             LocationState::new_accessed(Permission::new_disabled(), IdempotentForeignAccess::None), // this will be overwritten
         );
@@ -673,7 +673,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 trace!("Tree Borrows tag {tag:?} exposed in {alloc_id:?}");
                 alloc_extra.borrow_tracker_tb().borrow_mut().expose_tag(tag);
             }
-            AllocKind::Function | AllocKind::VTable | AllocKind::Dead => {
+            AllocKind::Function | AllocKind::Virtual | AllocKind::Dead => {
                 // No tree borrows on these allocations.
             }
         }
diff --git a/src/tools/miri/src/borrow_tracker/tree_borrows/tree.rs b/src/tools/miri/src/borrow_tracker/tree_borrows/tree.rs
index 48e4a19e263..1f29bcfc2b0 100644
--- a/src/tools/miri/src/borrow_tracker/tree_borrows/tree.rs
+++ b/src/tools/miri/src/borrow_tracker/tree_borrows/tree.rs
@@ -247,7 +247,7 @@ pub struct Tree {
     /// `unwrap` any `perm.get(key)`.
     ///
     /// We do uphold the fact that `keys(perms)` is a subset of `keys(nodes)`
-    pub(super) rperms: RangeMap<UniValMap<LocationState>>,
+    pub(super) rperms: DedupRangeMap<UniValMap<LocationState>>,
     /// The index of the root node.
     pub(super) root: UniIndex,
 }
@@ -609,7 +609,7 @@ impl Tree {
                     IdempotentForeignAccess::None,
                 ),
             );
-            RangeMap::new(size, perms)
+            DedupRangeMap::new(size, perms)
         };
         Self { root: root_idx, nodes, rperms, tag_mapping }
     }
@@ -631,7 +631,7 @@ impl<'tcx> Tree {
         base_offset: Size,
         parent_tag: BorTag,
         new_tag: BorTag,
-        initial_perms: RangeMap<LocationState>,
+        initial_perms: DedupRangeMap<LocationState>,
         default_perm: Permission,
         protected: bool,
         span: Span,
diff --git a/src/tools/miri/src/concurrency/data_race.rs b/src/tools/miri/src/concurrency/data_race.rs
index b5e7e9d0ac0..38d76f5cf73 100644
--- a/src/tools/miri/src/concurrency/data_race.rs
+++ b/src/tools/miri/src/concurrency/data_race.rs
@@ -997,7 +997,7 @@ pub trait EvalContextExt<'tcx>: MiriInterpCxExt<'tcx> {
 #[derive(Debug, Clone)]
 pub struct VClockAlloc {
     /// Assigning each byte a MemoryCellClocks.
-    alloc_ranges: RefCell<RangeMap<MemoryCellClocks>>,
+    alloc_ranges: RefCell<DedupRangeMap<MemoryCellClocks>>,
 }
 
 impl VisitProvenance for VClockAlloc {
@@ -1045,7 +1045,7 @@ impl VClockAlloc {
                 (VTimestamp::ZERO, global.thread_index(ThreadId::MAIN_THREAD)),
         };
         VClockAlloc {
-            alloc_ranges: RefCell::new(RangeMap::new(
+            alloc_ranges: RefCell::new(DedupRangeMap::new(
                 len,
                 MemoryCellClocks::new(alloc_timestamp, alloc_index),
             )),
diff --git a/src/tools/miri/src/concurrency/mod.rs b/src/tools/miri/src/concurrency/mod.rs
index 49bcc0d30b5..c2ea8a00dec 100644
--- a/src/tools/miri/src/concurrency/mod.rs
+++ b/src/tools/miri/src/concurrency/mod.rs
@@ -2,7 +2,6 @@ pub mod cpu_affinity;
 pub mod data_race;
 mod data_race_handler;
 pub mod init_once;
-mod range_object_map;
 pub mod sync;
 pub mod thread;
 mod vector_clock;
diff --git a/src/tools/miri/src/concurrency/thread.rs b/src/tools/miri/src/concurrency/thread.rs
index a4e93f9222c..878afdf2517 100644
--- a/src/tools/miri/src/concurrency/thread.rs
+++ b/src/tools/miri/src/concurrency/thread.rs
@@ -186,15 +186,15 @@ pub struct Thread<'tcx> {
     /// The join status.
     join_status: ThreadJoinStatus,
 
-    /// Stack of active panic payloads for the current thread. Used for storing
-    /// the argument of the call to `miri_start_unwind` (the panic payload) when unwinding.
+    /// Stack of active unwind payloads for the current thread. Used for storing
+    /// the argument of the call to `miri_start_unwind` (the payload) when unwinding.
     /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
     ///
     /// In real unwinding, the payload gets passed as an argument to the landing pad,
     /// which then forwards it to 'Resume'. However this argument is implicit in MIR,
     /// so we have to store it out-of-band. When there are multiple active unwinds,
     /// the innermost one is always caught first, so we can store them as a stack.
-    pub(crate) panic_payloads: Vec<ImmTy<'tcx>>,
+    pub(crate) unwind_payloads: Vec<ImmTy<'tcx>>,
 
     /// Last OS error location in memory. It is a 32-bit integer.
     pub(crate) last_error: Option<MPlaceTy<'tcx>>,
@@ -282,7 +282,7 @@ impl<'tcx> Thread<'tcx> {
             stack: Vec::new(),
             top_user_relevant_frame: None,
             join_status: ThreadJoinStatus::Joinable,
-            panic_payloads: Vec::new(),
+            unwind_payloads: Vec::new(),
             last_error: None,
             on_stack_empty,
         }
@@ -292,7 +292,7 @@ impl<'tcx> Thread<'tcx> {
 impl VisitProvenance for Thread<'_> {
     fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
         let Thread {
-            panic_payloads: panic_payload,
+            unwind_payloads: panic_payload,
             last_error,
             stack,
             top_user_relevant_frame: _,
@@ -677,6 +677,8 @@ trait EvalContextPrivExt<'tcx>: MiriInterpCxExt<'tcx> {
     fn run_on_stack_empty(&mut self) -> InterpResult<'tcx, Poll<()>> {
         let this = self.eval_context_mut();
         // Inform GenMC that a thread has finished all user code. GenMC needs to know this for scheduling.
+        // FIXME(GenMC): Thread-local destructors *are* user code, so this is odd. Also now that we
+        // support pre-main constructors, it can get called there as well.
         if let Some(genmc_ctx) = this.machine.data_race.as_genmc_ref() {
             let thread_id = this.active_thread();
             genmc_ctx.handle_thread_stack_empty(thread_id);
diff --git a/src/tools/miri/src/concurrency/weak_memory.rs b/src/tools/miri/src/concurrency/weak_memory.rs
index 95c010be2fd..a752ef7e454 100644
--- a/src/tools/miri/src/concurrency/weak_memory.rs
+++ b/src/tools/miri/src/concurrency/weak_memory.rs
@@ -90,9 +90,9 @@ use rustc_data_structures::fx::FxHashMap;
 
 use super::AllocDataRaceHandler;
 use super::data_race::{GlobalState as DataRaceState, ThreadClockSet};
-use super::range_object_map::{AccessType, RangeObjectMap};
 use super::vector_clock::{VClock, VTimestamp, VectorIdx};
 use crate::concurrency::GlobalDataRaceHandler;
+use crate::data_structures::range_object_map::{AccessType, RangeObjectMap};
 use crate::*;
 
 pub type AllocState = StoreBufferAlloc;
diff --git a/src/tools/miri/src/range_map.rs b/src/tools/miri/src/data_structures/dedup_range_map.rs
index 29a5a8537a4..56e9883b1ca 100644
--- a/src/tools/miri/src/range_map.rs
+++ b/src/tools/miri/src/data_structures/dedup_range_map.rs
@@ -17,18 +17,18 @@ struct Elem<T> {
     data: T,
 }
 #[derive(Clone, Debug)]
-pub struct RangeMap<T> {
+pub struct DedupRangeMap<T> {
     v: Vec<Elem<T>>,
 }
 
-impl<T> RangeMap<T> {
+impl<T> DedupRangeMap<T> {
     /// Creates a new `RangeMap` for the given size, and with the given initial value used for
     /// the entire range.
     #[inline(always)]
-    pub fn new(size: Size, init: T) -> RangeMap<T> {
+    pub fn new(size: Size, init: T) -> DedupRangeMap<T> {
         let size = size.bytes();
         let v = if size > 0 { vec![Elem { range: 0..size, data: init }] } else { Vec::new() };
-        RangeMap { v }
+        DedupRangeMap { v }
     }
 
     pub fn size(&self) -> Size {
@@ -246,7 +246,7 @@ mod tests {
     use super::*;
 
     /// Query the map at every offset in the range and collect the results.
-    fn to_vec<T: Copy>(map: &RangeMap<T>, offset: u64, len: u64) -> Vec<T> {
+    fn to_vec<T: Copy>(map: &DedupRangeMap<T>, offset: u64, len: u64) -> Vec<T> {
         (offset..offset + len)
             .map(|i| {
                 map.iter(Size::from_bytes(i), Size::from_bytes(1)).next().map(|(_, &t)| t).unwrap()
@@ -256,7 +256,7 @@ mod tests {
 
     #[test]
     fn basic_insert() {
-        let mut map = RangeMap::<i32>::new(Size::from_bytes(20), -1);
+        let mut map = DedupRangeMap::<i32>::new(Size::from_bytes(20), -1);
         // Insert.
         for (_, x) in map.iter_mut(Size::from_bytes(10), Size::from_bytes(1)) {
             *x = 42;
@@ -278,7 +278,7 @@ mod tests {
 
     #[test]
     fn gaps() {
-        let mut map = RangeMap::<i32>::new(Size::from_bytes(20), -1);
+        let mut map = DedupRangeMap::<i32>::new(Size::from_bytes(20), -1);
         for (_, x) in map.iter_mut(Size::from_bytes(11), Size::from_bytes(1)) {
             *x = 42;
         }
@@ -319,26 +319,26 @@ mod tests {
     #[test]
     #[should_panic]
     fn out_of_range_iter_mut() {
-        let mut map = RangeMap::<i32>::new(Size::from_bytes(20), -1);
+        let mut map = DedupRangeMap::<i32>::new(Size::from_bytes(20), -1);
         let _ = map.iter_mut(Size::from_bytes(11), Size::from_bytes(11));
     }
 
     #[test]
     #[should_panic]
     fn out_of_range_iter() {
-        let map = RangeMap::<i32>::new(Size::from_bytes(20), -1);
+        let map = DedupRangeMap::<i32>::new(Size::from_bytes(20), -1);
         let _ = map.iter(Size::from_bytes(11), Size::from_bytes(11));
     }
 
     #[test]
     fn empty_map_iter() {
-        let map = RangeMap::<i32>::new(Size::from_bytes(0), -1);
+        let map = DedupRangeMap::<i32>::new(Size::from_bytes(0), -1);
         let _ = map.iter(Size::from_bytes(0), Size::from_bytes(0));
     }
 
     #[test]
     fn empty_map_iter_mut() {
-        let mut map = RangeMap::<i32>::new(Size::from_bytes(0), -1);
+        let mut map = DedupRangeMap::<i32>::new(Size::from_bytes(0), -1);
         let _ = map.iter_mut(Size::from_bytes(0), Size::from_bytes(0));
     }
 }
diff --git a/src/tools/miri/src/data_structures/mod.rs b/src/tools/miri/src/data_structures/mod.rs
new file mode 100644
index 00000000000..d4468bc57ea
--- /dev/null
+++ b/src/tools/miri/src/data_structures/mod.rs
@@ -0,0 +1,3 @@
+pub mod dedup_range_map;
+pub mod mono_hash_map;
+pub mod range_object_map;
diff --git a/src/tools/miri/src/mono_hash_map.rs b/src/tools/miri/src/data_structures/mono_hash_map.rs
index 220233f8ff5..220233f8ff5 100644
--- a/src/tools/miri/src/mono_hash_map.rs
+++ b/src/tools/miri/src/data_structures/mono_hash_map.rs
diff --git a/src/tools/miri/src/concurrency/range_object_map.rs b/src/tools/miri/src/data_structures/range_object_map.rs
index 4c9cf3dc635..4c9cf3dc635 100644
--- a/src/tools/miri/src/concurrency/range_object_map.rs
+++ b/src/tools/miri/src/data_structures/range_object_map.rs
diff --git a/src/tools/miri/src/eval.rs b/src/tools/miri/src/eval.rs
index 425a136dfa5..be6404f64e8 100644
--- a/src/tools/miri/src/eval.rs
+++ b/src/tools/miri/src/eval.rs
@@ -11,14 +11,14 @@ use rustc_abi::ExternAbi;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_hir::def::Namespace;
 use rustc_hir::def_id::DefId;
-use rustc_middle::ty::layout::LayoutCx;
+use rustc_middle::ty::layout::{HasTyCtxt, HasTypingEnv, LayoutCx};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_session::config::EntryFnType;
 
 use crate::concurrency::GenmcCtx;
 use crate::concurrency::thread::TlsAllocAction;
 use crate::diagnostics::report_leaks;
-use crate::shims::tls;
+use crate::shims::{global_ctor, tls};
 use crate::*;
 
 #[derive(Copy, Clone, Debug)]
@@ -216,9 +216,17 @@ impl Default for MiriConfig {
 }
 
 /// The state of the main thread. Implementation detail of `on_main_stack_empty`.
-#[derive(Default, Debug)]
+#[derive(Debug)]
 enum MainThreadState<'tcx> {
-    #[default]
+    GlobalCtors {
+        ctor_state: global_ctor::GlobalCtorState<'tcx>,
+        /// The main function to call.
+        entry_id: DefId,
+        entry_type: MiriEntryFnType,
+        /// Arguments passed to `main`.
+        argc: ImmTy<'tcx>,
+        argv: ImmTy<'tcx>,
+    },
     Running,
     TlsDtors(tls::TlsDtorsState<'tcx>),
     Yield {
@@ -234,6 +242,15 @@ impl<'tcx> MainThreadState<'tcx> {
     ) -> InterpResult<'tcx, Poll<()>> {
         use MainThreadState::*;
         match self {
+            GlobalCtors { ctor_state, entry_id, entry_type, argc, argv } => {
+                match ctor_state.on_stack_empty(this)? {
+                    Poll::Pending => {} // just keep going
+                    Poll::Ready(()) => {
+                        call_main(this, *entry_id, *entry_type, argc.clone(), argv.clone())?;
+                        *self = Running;
+                    }
+                }
+            }
             Running => {
                 *self = TlsDtors(Default::default());
             }
@@ -309,13 +326,6 @@ pub fn create_ecx<'tcx>(
         MiriMachine::new(config, layout_cx, genmc_ctx),
     );
 
-    // Some parts of initialization require a full `InterpCx`.
-    MiriMachine::late_init(&mut ecx, config, {
-        let mut state = MainThreadState::default();
-        // Cannot capture anything GC-relevant here.
-        Box::new(move |m| state.on_main_stack_empty(m))
-    })?;
-
     // Make sure we have MIR. We check MIR for some stable monomorphic function in libcore.
     let sentinel =
         helpers::try_resolve_path(tcx, &["core", "ascii", "escape_default"], Namespace::ValueNS);
@@ -326,15 +336,9 @@ pub fn create_ecx<'tcx>(
         );
     }
 
-    // Setup first stack frame.
-    let entry_instance = ty::Instance::mono(tcx, entry_id);
-
-    // First argument is constructed later, because it's skipped for `miri_start.`
-
-    // Second argument (argc): length of `config.args`.
+    // Compute argc and argv from `config.args`.
     let argc =
         ImmTy::from_int(i64::try_from(config.args.len()).unwrap(), ecx.machine.layouts.isize);
-    // Third argument (`argv`): created from `config.args`.
     let argv = {
         // Put each argument in memory, collect pointers.
         let mut argvs = Vec::<Immediate<Provenance>>::with_capacity(config.args.len());
@@ -359,7 +363,7 @@ pub fn create_ecx<'tcx>(
             ecx.write_immediate(arg, &place)?;
         }
         ecx.mark_immutable(&argvs_place);
-        // Store `argc` and `argv` for macOS `_NSGetArg{c,v}`.
+        // Store `argc` and `argv` for macOS `_NSGetArg{c,v}`, and for the GC to see them.
         {
             let argc_place =
                 ecx.allocate(ecx.machine.layouts.isize, MiriMemoryKind::Machine.into())?;
@@ -374,7 +378,7 @@ pub fn create_ecx<'tcx>(
             ecx.machine.argv = Some(argv_place.ptr());
         }
         // Store command line as UTF-16 for Windows `GetCommandLineW`.
-        {
+        if tcx.sess.target.os == "windows" {
             // Construct a command string with all the arguments.
             let cmd_utf16: Vec<u16> = args_to_utf16_command_string(config.args.iter());
 
@@ -395,11 +399,43 @@ pub fn create_ecx<'tcx>(
         ImmTy::from_immediate(imm, layout)
     };
 
+    // Some parts of initialization require a full `InterpCx`.
+    MiriMachine::late_init(&mut ecx, config, {
+        let mut main_thread_state = MainThreadState::GlobalCtors {
+            entry_id,
+            entry_type,
+            argc,
+            argv,
+            ctor_state: global_ctor::GlobalCtorState::default(),
+        };
+
+        // Cannot capture anything GC-relevant here.
+        // `argc` and `argv` *are* GC_relevant, but they also get stored in `machine.argc` and
+        // `machine.argv` so we are good.
+        Box::new(move |m| main_thread_state.on_main_stack_empty(m))
+    })?;
+
+    interp_ok(ecx)
+}
+
+// Call the entry function.
+fn call_main<'tcx>(
+    ecx: &mut MiriInterpCx<'tcx>,
+    entry_id: DefId,
+    entry_type: MiriEntryFnType,
+    argc: ImmTy<'tcx>,
+    argv: ImmTy<'tcx>,
+) -> InterpResult<'tcx, ()> {
+    let tcx = ecx.tcx();
+
+    // Setup first stack frame.
+    let entry_instance = ty::Instance::mono(tcx, entry_id);
+
     // Return place (in static memory so that it does not count as leak).
     let ret_place = ecx.allocate(ecx.machine.layouts.isize, MiriMemoryKind::Machine.into())?;
     ecx.machine.main_fn_ret_place = Some(ret_place.clone());
-    // Call start function.
 
+    // Call start function.
     match entry_type {
         MiriEntryFnType::Rustc(EntryFnType::Main { .. }) => {
             let start_id = tcx.lang_items().start_fn().unwrap_or_else(|| {
@@ -409,7 +445,7 @@ pub fn create_ecx<'tcx>(
             let main_ret_ty = main_ret_ty.no_bound_vars().unwrap();
             let start_instance = ty::Instance::try_resolve(
                 tcx,
-                typing_env,
+                ecx.typing_env(),
                 start_id,
                 tcx.mk_args(&[ty::GenericArg::from(main_ret_ty)]),
             )
@@ -427,7 +463,7 @@ pub fn create_ecx<'tcx>(
                 ExternAbi::Rust,
                 &[
                     ImmTy::from_scalar(
-                        Scalar::from_pointer(main_ptr, &ecx),
+                        Scalar::from_pointer(main_ptr, ecx),
                         // FIXME use a proper fn ptr type
                         ecx.machine.layouts.const_raw_ptr,
                     ),
@@ -450,7 +486,7 @@ pub fn create_ecx<'tcx>(
         }
     }
 
-    interp_ok(ecx)
+    interp_ok(())
 }
 
 /// Evaluates the entry function specified by `entry_id`.
diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs
index c150dc16b07..ccfff7fa94b 100644
--- a/src/tools/miri/src/helpers.rs
+++ b/src/tools/miri/src/helpers.rs
@@ -13,7 +13,7 @@ use rustc_index::IndexVec;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
-use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, MaybeResult, TyAndLayout};
+use rustc_middle::ty::layout::{LayoutOf, MaybeResult, TyAndLayout};
 use rustc_middle::ty::{self, Binder, FloatTy, FnSig, IntTy, Ty, TyCtxt, UintTy};
 use rustc_session::config::CrateType;
 use rustc_span::{Span, Symbol};
@@ -1235,8 +1235,11 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         interp_ok(())
     }
 
-    /// Lookup an array of immediates stored as a linker section of name `name`.
-    fn lookup_link_section(&mut self, name: &str) -> InterpResult<'tcx, Vec<ImmTy<'tcx>>> {
+    /// Lookup an array of immediates from any linker sections matching the provided predicate.
+    fn lookup_link_section(
+        &mut self,
+        include_name: impl Fn(&str) -> bool,
+    ) -> InterpResult<'tcx, Vec<ImmTy<'tcx>>> {
         let this = self.eval_context_mut();
         let tcx = this.tcx.tcx;
 
@@ -1247,7 +1250,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             let Some(link_section) = attrs.link_section else {
                 return interp_ok(());
             };
-            if link_section.as_str() == name {
+            if include_name(link_section.as_str()) {
                 let instance = ty::Instance::mono(tcx, def_id);
                 let const_val = this.eval_global(instance).unwrap_or_else(|err| {
                     panic!(
@@ -1431,3 +1434,44 @@ impl ToU64 for usize {
         self.try_into().unwrap()
     }
 }
+
+/// This struct is needed to enforce `#[must_use]` on values produced by [enter_trace_span] even
+/// when the "tracing" feature is not enabled.
+#[must_use]
+pub struct MaybeEnteredTraceSpan {
+    #[cfg(feature = "tracing")]
+    pub _entered_span: tracing::span::EnteredSpan,
+}
+
+/// Enters a [tracing::info_span] only if the "tracing" feature is enabled, otherwise does nothing.
+/// This is like [rustc_const_eval::enter_trace_span] except that it does not depend on the
+/// [Machine] trait to check if tracing is enabled, because from the Miri codebase we can directly
+/// check whether the "tracing" feature is enabled, unlike from the rustc_const_eval codebase.
+///
+/// In addition to the syntax accepted by [tracing::span!], this macro optionally allows passing
+/// the span name (i.e. the first macro argument) in the form `NAME::SUBNAME` (without quotes) to
+/// indicate that the span has name "NAME" (usually the name of the component) and has an additional
+/// more specific name "SUBNAME" (usually the function name). The latter is passed to the [tracing]
+/// infrastructure as a span field with the name "NAME". This allows not being distracted by
+/// subnames when looking at the trace in <https://ui.perfetto.dev>, but when deeper introspection
+/// is needed within a component, it's still possible to view the subnames directly in the UI by
+/// selecting a span, clicking on the "NAME" argument on the right, and clicking on "Visualize
+/// argument values".
+/// ```rust
+/// // for example, the first will expand to the second
+/// enter_trace_span!(borrow_tracker::on_stack_pop, /* ... */)
+/// enter_trace_span!("borrow_tracker", borrow_tracker = "on_stack_pop", /* ... */)
+/// ```
+#[macro_export]
+macro_rules! enter_trace_span {
+    ($name:ident :: $subname:ident $($tt:tt)*) => {{
+        enter_trace_span!(stringify!($name), $name = %stringify!(subname) $($tt)*)
+    }};
+
+    ($($tt:tt)*) => {
+        $crate::MaybeEnteredTraceSpan {
+            #[cfg(feature = "tracing")]
+            _entered_span: tracing::info_span!($($tt)*).entered()
+        }
+    };
+}
diff --git a/src/tools/miri/src/lib.rs b/src/tools/miri/src/lib.rs
index c86e33e5185..a591d21071d 100644
--- a/src/tools/miri/src/lib.rs
+++ b/src/tools/miri/src/lib.rs
@@ -15,6 +15,7 @@
 #![feature(unqualified_local_imports)]
 #![feature(derive_coerce_pointee)]
 #![feature(arbitrary_self_types)]
+#![feature(iter_advance_by)]
 // Configure clippy and other lints
 #![allow(
     clippy::collapsible_else_if,
@@ -75,16 +76,15 @@ mod alloc_addresses;
 mod borrow_tracker;
 mod clock;
 mod concurrency;
+mod data_structures;
 mod diagnostics;
 mod eval;
 mod helpers;
 mod intrinsics;
 mod machine;
 mod math;
-mod mono_hash_map;
 mod operator;
 mod provenance_gc;
-mod range_map;
 mod shims;
 
 // Establish a "crate-wide prelude": we often import `crate::*`.
@@ -97,10 +97,10 @@ pub use rustc_const_eval::interpret::{self, AllocMap, Provenance as _};
 use rustc_middle::{bug, span_bug};
 use tracing::{info, trace};
 
-//#[cfg(target_os = "linux")]
-//pub mod native_lib {
-//    pub use crate::shims::{init_sv, register_retcode_sv};
-//}
+#[cfg(target_os = "linux")]
+pub mod native_lib {
+    pub use crate::shims::{init_sv, register_retcode_sv};
+}
 
 // Type aliases that set the provenance parameter.
 pub type Pointer = interpret::Pointer<Option<machine::Provenance>>;
@@ -132,6 +132,8 @@ pub use crate::concurrency::thread::{
     ThreadManager, TimeoutAnchor, TimeoutClock, UnblockKind,
 };
 pub use crate::concurrency::{GenmcConfig, GenmcCtx};
+pub use crate::data_structures::dedup_range_map::DedupRangeMap;
+pub use crate::data_structures::mono_hash_map::MonoHashMap;
 pub use crate::diagnostics::{
     EvalContextExt as _, NonHaltingDiagnostic, TerminationInfo, report_error,
 };
@@ -139,24 +141,25 @@ pub use crate::eval::{
     AlignmentCheck, BacktraceStyle, IsolatedOp, MiriConfig, MiriEntryFnType, RejectOpWith,
     ValidationMode, create_ecx, eval_entry,
 };
-pub use crate::helpers::{AccessKind, EvalContextExt as _, ToU64 as _, ToUsize as _};
+pub use crate::helpers::{
+    AccessKind, EvalContextExt as _, MaybeEnteredTraceSpan, ToU64 as _, ToUsize as _,
+};
 pub use crate::intrinsics::EvalContextExt as _;
 pub use crate::machine::{
     AllocExtra, DynMachineCallback, FrameExtra, MachineCallback, MemoryKind, MiriInterpCx,
     MiriInterpCxExt, MiriMachine, MiriMemoryKind, PrimitiveLayouts, Provenance, ProvenanceExtra,
 };
-pub use crate::mono_hash_map::MonoHashMap;
 pub use crate::operator::EvalContextExt as _;
 pub use crate::provenance_gc::{EvalContextExt as _, LiveAllocs, VisitProvenance, VisitWith};
-pub use crate::range_map::RangeMap;
 pub use crate::shims::EmulateItemResult;
 pub use crate::shims::env::{EnvVars, EvalContextExt as _};
 pub use crate::shims::foreign_items::{DynSym, EvalContextExt as _};
 pub use crate::shims::io_error::{EvalContextExt as _, IoError, LibcError};
 pub use crate::shims::os_str::EvalContextExt as _;
-pub use crate::shims::panic::{CatchUnwindData, EvalContextExt as _};
+pub use crate::shims::panic::EvalContextExt as _;
 pub use crate::shims::time::EvalContextExt as _;
 pub use crate::shims::tls::TlsData;
+pub use crate::shims::unwind::{CatchUnwindData, EvalContextExt as _};
 
 /// Insert rustc arguments at the beginning of the argument list that Miri wants to be
 /// set per default, for maximal validation power.
diff --git a/src/tools/miri/src/machine.rs b/src/tools/miri/src/machine.rs
index 35399dbf4cb..f309e34c75b 100644
--- a/src/tools/miri/src/machine.rs
+++ b/src/tools/miri/src/machine.rs
@@ -1086,7 +1086,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
         ecx: &MiriInterpCx<'tcx>,
         instance: ty::Instance<'tcx>,
     ) -> InterpResult<'tcx> {
-        let attrs = ecx.tcx.codegen_fn_attrs(instance.def_id());
+        let attrs = ecx.tcx.codegen_instance_attrs(instance.def);
         if attrs
             .target_features
             .iter()
@@ -1790,7 +1790,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
                 ecx.tcx.sess.opts.unstable_opts.cross_crate_inline_threshold,
                 InliningThreshold::Always
             ) || !matches!(
-                ecx.tcx.codegen_fn_attrs(instance.def_id()).inline,
+                ecx.tcx.codegen_instance_attrs(instance.def).inline,
                 InlineAttr::Never
             );
             !is_generic && !can_be_inlined
@@ -1828,8 +1828,11 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
 
     fn enter_trace_span(span: impl FnOnce() -> tracing::Span) -> impl EnteredTraceSpan {
         #[cfg(feature = "tracing")]
-        { span().entered() }
+        {
+            span().entered()
+        }
         #[cfg(not(feature = "tracing"))]
+        #[expect(clippy::unused_unit)]
         {
             let _ = span; // so we avoid the "unused variable" warning
             ()
diff --git a/src/tools/miri/src/shims/global_ctor.rs b/src/tools/miri/src/shims/global_ctor.rs
new file mode 100644
index 00000000000..c56251bbe63
--- /dev/null
+++ b/src/tools/miri/src/shims/global_ctor.rs
@@ -0,0 +1,98 @@
+//! Implement global constructors.
+
+use std::task::Poll;
+
+use rustc_abi::ExternAbi;
+use rustc_target::spec::BinaryFormat;
+
+use crate::*;
+
+#[derive(Debug, Default)]
+pub struct GlobalCtorState<'tcx>(GlobalCtorStatePriv<'tcx>);
+
+#[derive(Debug, Default)]
+enum GlobalCtorStatePriv<'tcx> {
+    #[default]
+    Init,
+    /// The list of constructor functions that we still have to call.
+    Ctors(Vec<ImmTy<'tcx>>),
+    Done,
+}
+
+impl<'tcx> GlobalCtorState<'tcx> {
+    pub fn on_stack_empty(
+        &mut self,
+        this: &mut MiriInterpCx<'tcx>,
+    ) -> InterpResult<'tcx, Poll<()>> {
+        use GlobalCtorStatePriv::*;
+        let new_state = 'new_state: {
+            match &mut self.0 {
+                Init => {
+                    let this = this.eval_context_mut();
+
+                    // Lookup constructors from the relevant magic link section.
+                    let ctors = match this.tcx.sess.target.binary_format {
+                        // Read the CRT library section on Windows.
+                        BinaryFormat::Coff =>
+                            this.lookup_link_section(|section| section == ".CRT$XCU")?,
+
+                        // Read the `__mod_init_func` section on macOS.
+                        BinaryFormat::MachO =>
+                            this.lookup_link_section(|section| {
+                                let mut parts = section.splitn(3, ',');
+                                let (segment_name, section_name, section_type) =
+                                    (parts.next(), parts.next(), parts.next());
+
+                                segment_name == Some("__DATA")
+                                    && section_name == Some("__mod_init_func")
+                                    // The `mod_init_funcs` directive ensures that the
+                                    // `S_MOD_INIT_FUNC_POINTERS` flag is set on the section. LLVM
+                                    // adds this automatically so we currently do not require it.
+                                    // FIXME: is this guaranteed LLVM behavior? If not, we shouldn't
+                                    // implicitly add it here. Also see
+                                    // <https://github.com/rust-lang/miri/pull/4459#discussion_r2200115629>.
+                                    && matches!(section_type, None | Some("mod_init_funcs"))
+                            })?,
+
+                        // Read the standard `.init_array` section on platforms that use ELF, or WASM,
+                        // which supports the same linker directive.
+                        // FIXME: Add support for `.init_array.N` and `.ctors`?
+                        BinaryFormat::Elf | BinaryFormat::Wasm =>
+                            this.lookup_link_section(|section| section == ".init_array")?,
+
+                        // Other platforms have no global ctor support.
+                        _ => break 'new_state Done,
+                    };
+
+                    break 'new_state Ctors(ctors);
+                }
+                Ctors(ctors) => {
+                    if let Some(ctor) = ctors.pop() {
+                        let this = this.eval_context_mut();
+
+                        let ctor = ctor.to_scalar().to_pointer(this)?;
+                        let thread_callback = this.get_ptr_fn(ctor)?.as_instance()?;
+
+                        // The signature of this function is `unsafe extern "C" fn()`.
+                        this.call_function(
+                            thread_callback,
+                            ExternAbi::C { unwind: false },
+                            &[],
+                            None,
+                            ReturnContinuation::Stop { cleanup: true },
+                        )?;
+
+                        return interp_ok(Poll::Pending); // we stay in this state (but `ctors` got shorter)
+                    }
+
+                    // No more constructors to run.
+                    break 'new_state Done;
+                }
+                Done => return interp_ok(Poll::Ready(())),
+            }
+        };
+
+        self.0 = new_state;
+        interp_ok(Poll::Pending)
+    }
+}
diff --git a/src/tools/miri/src/shims/mod.rs b/src/tools/miri/src/shims/mod.rs
index f09fc546b3e..75540f6f150 100644
--- a/src/tools/miri/src/shims/mod.rs
+++ b/src/tools/miri/src/shims/mod.rs
@@ -14,15 +14,17 @@ mod x86;
 pub mod env;
 pub mod extern_static;
 pub mod foreign_items;
+pub mod global_ctor;
 pub mod io_error;
 pub mod os_str;
 pub mod panic;
 pub mod time;
 pub mod tls;
+pub mod unwind;
 
 pub use self::files::FdTable;
-//#[cfg(target_os = "linux")]
-//pub use self::native_lib::trace::{init_sv, register_retcode_sv};
+#[cfg(target_os = "linux")]
+pub use self::native_lib::trace::{init_sv, register_retcode_sv};
 pub use self::unix::{DirTable, EpollInterestTable};
 
 /// What needs to be done after emulating an item (a shim or an intrinsic) is done.
diff --git a/src/tools/miri/src/shims/native_lib/mod.rs b/src/tools/miri/src/shims/native_lib/mod.rs
index 02c3bde036d..fb7b1df41a4 100644
--- a/src/tools/miri/src/shims/native_lib/mod.rs
+++ b/src/tools/miri/src/shims/native_lib/mod.rs
@@ -1,9 +1,5 @@
 //! Implements calling functions from a native library.
 
-// FIXME: disabled since it fails to build on many targets.
-//#[cfg(target_os = "linux")]
-//pub mod trace;
-
 use std::ops::Deref;
 
 use libffi::high::call as ffi;
@@ -13,14 +9,68 @@ use rustc_middle::mir::interpret::Pointer;
 use rustc_middle::ty::{self as ty, IntTy, UintTy};
 use rustc_span::Symbol;
 
-//#[cfg(target_os = "linux")]
-//use self::trace::Supervisor;
+#[cfg_attr(
+    not(all(
+        target_os = "linux",
+        target_env = "gnu",
+        any(target_arch = "x86", target_arch = "x86_64")
+    )),
+    path = "trace/stub.rs"
+)]
+pub mod trace;
+
 use crate::*;
 
-//#[cfg(target_os = "linux")]
-//type CallResult<'tcx> = InterpResult<'tcx, (ImmTy<'tcx>, Option<self::trace::messages::MemEvents>)>;
-//#[cfg(not(target_os = "linux"))]
-type CallResult<'tcx> = InterpResult<'tcx, (ImmTy<'tcx>, Option<!>)>;
+/// The final results of an FFI trace, containing every relevant event detected
+/// by the tracer.
+#[allow(dead_code)]
+#[cfg_attr(target_os = "linux", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug)]
+pub struct MemEvents {
+    /// An list of memory accesses that occurred, in the order they occurred in.
+    pub acc_events: Vec<AccessEvent>,
+}
+
+/// A single memory access.
+#[allow(dead_code)]
+#[cfg_attr(target_os = "linux", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Clone, Debug)]
+pub enum AccessEvent {
+    /// A read occurred on this memory range.
+    Read(AccessRange),
+    /// A write may have occurred on this memory range.
+    /// Some instructions *may* write memory without *always* doing that,
+    /// so this can be an over-approximation.
+    /// The range info, however, is reliable if the access did happen.
+    /// If the second field is true, the access definitely happened.
+    Write(AccessRange, bool),
+}
+
+impl AccessEvent {
+    fn get_range(&self) -> AccessRange {
+        match self {
+            AccessEvent::Read(access_range) => access_range.clone(),
+            AccessEvent::Write(access_range, _) => access_range.clone(),
+        }
+    }
+}
+
+/// The memory touched by a given access.
+#[allow(dead_code)]
+#[cfg_attr(target_os = "linux", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Clone, Debug)]
+pub struct AccessRange {
+    /// The base address in memory where an access occurred.
+    pub addr: usize,
+    /// The number of bytes affected from the base.
+    pub size: usize,
+}
+
+impl AccessRange {
+    fn end(&self) -> usize {
+        self.addr.strict_add(self.size)
+    }
+}
 
 impl<'tcx> EvalContextExtPriv<'tcx> for crate::MiriInterpCx<'tcx> {}
 trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
@@ -31,18 +81,17 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
         dest: &MPlaceTy<'tcx>,
         ptr: CodePtr,
         libffi_args: Vec<libffi::high::Arg<'a>>,
-    ) -> CallResult<'tcx> {
+    ) -> InterpResult<'tcx, (crate::ImmTy<'tcx>, Option<MemEvents>)> {
         let this = self.eval_context_mut();
-        //#[cfg(target_os = "linux")]
-        //let alloc = this.machine.allocator.as_ref().unwrap();
-
-        // SAFETY: We don't touch the machine memory past this point.
-        //#[cfg(target_os = "linux")]
-        //let (guard, stack_ptr) = unsafe { Supervisor::start_ffi(alloc) };
+        #[cfg(target_os = "linux")]
+        let alloc = this.machine.allocator.as_ref().unwrap();
+        #[cfg(not(target_os = "linux"))]
+        // Placeholder value.
+        let alloc = ();
 
-        // Call the function (`ptr`) with arguments `libffi_args`, and obtain the return value
-        // as the specified primitive integer type
-        let res = 'res: {
+        trace::Supervisor::do_ffi(alloc, || {
+            // Call the function (`ptr`) with arguments `libffi_args`, and obtain the return value
+            // as the specified primitive integer type
             let scalar = match dest.layout.ty.kind() {
                 // ints
                 ty::Int(IntTy::I8) => {
@@ -93,7 +142,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // have the output_type `Tuple([])`.
                 ty::Tuple(t_list) if (*t_list).deref().is_empty() => {
                     unsafe { ffi::call::<()>(ptr, libffi_args.as_slice()) };
-                    break 'res interp_ok(ImmTy::uninit(dest.layout));
+                    return interp_ok(ImmTy::uninit(dest.layout));
                 }
                 ty::RawPtr(..) => {
                     let x = unsafe { ffi::call::<*const ()>(ptr, libffi_args.as_slice()) };
@@ -101,23 +150,14 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     Scalar::from_pointer(ptr, this)
                 }
                 _ =>
-                    break 'res Err(err_unsup_format!(
+                    return Err(err_unsup_format!(
                         "unsupported return type for native call: {:?}",
                         link_name
                     ))
                     .into(),
             };
             interp_ok(ImmTy::from_scalar(scalar, dest.layout))
-        };
-
-        // SAFETY: We got the guard and stack pointer from start_ffi, and
-        // the allocator is the same
-        //#[cfg(target_os = "linux")]
-        //let events = unsafe { Supervisor::end_ffi(alloc, guard, stack_ptr) };
-        //#[cfg(not(target_os = "linux"))]
-        let events = None;
-
-        interp_ok((res?, events))
+        })
     }
 
     /// Get the pointer to the function of the specified name in the shared object file,
@@ -169,6 +209,73 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
         }
         None
     }
+
+    /// Applies the `events` to Miri's internal state. The event vector must be
+    /// ordered sequentially by when the accesses happened, and the sizes are
+    /// assumed to be exact.
+    fn tracing_apply_accesses(&mut self, events: MemEvents) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+
+        for evt in events.acc_events {
+            let evt_rg = evt.get_range();
+            // LLVM at least permits vectorising accesses to adjacent allocations,
+            // so we cannot assume 1 access = 1 allocation. :(
+            let mut rg = evt_rg.addr..evt_rg.end();
+            while let Some(curr) = rg.next() {
+                let Some(alloc_id) = this.alloc_id_from_addr(
+                    curr.to_u64(),
+                    rg.len().try_into().unwrap(),
+                    /* only_exposed_allocations */ true,
+                ) else {
+                    throw_ub_format!("Foreign code did an out-of-bounds access!")
+                };
+                let alloc = this.get_alloc_raw(alloc_id)?;
+                // The logical and physical address of the allocation coincide, so we can use
+                // this instead of `addr_from_alloc_id`.
+                let alloc_addr = alloc.get_bytes_unchecked_raw().addr();
+
+                // Determine the range inside the allocation that this access covers. This range is
+                // in terms of offsets from the start of `alloc`. The start of the overlap range
+                // will be `curr`; the end will be the minimum of the end of the allocation and the
+                // end of the access' range.
+                let overlap = curr.strict_sub(alloc_addr)
+                    ..std::cmp::min(alloc.len(), rg.end.strict_sub(alloc_addr));
+                // Skip forward however many bytes of the access are contained in the current
+                // allocation, subtracting 1 since the overlap range includes the current addr
+                // that was already popped off of the range.
+                rg.advance_by(overlap.len().strict_sub(1)).unwrap();
+
+                match evt {
+                    AccessEvent::Read(_) => {
+                        // FIXME: ProvenanceMap should have something like get_range().
+                        let p_map = alloc.provenance();
+                        for idx in overlap {
+                            // If a provenance was read by the foreign code, expose it.
+                            if let Some(prov) = p_map.get(Size::from_bytes(idx), this) {
+                                this.expose_provenance(prov)?;
+                            }
+                        }
+                    }
+                    AccessEvent::Write(_, certain) => {
+                        // Sometimes we aren't certain if a write happened, in which case we
+                        // only initialise that data if the allocation is mutable.
+                        if certain || alloc.mutability.is_mut() {
+                            let (alloc, cx) = this.get_alloc_raw_mut(alloc_id)?;
+                            alloc.process_native_write(
+                                &cx.tcx,
+                                Some(AllocRange {
+                                    start: Size::from_bytes(overlap.start),
+                                    size: Size::from_bytes(overlap.len()),
+                                }),
+                            )
+                        }
+                    }
+                }
+            }
+        }
+
+        interp_ok(())
+    }
 }
 
 impl<'tcx> EvalContextExt<'tcx> for crate::MiriInterpCx<'tcx> {}
@@ -194,6 +301,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             }
         };
 
+        // Do we have ptrace?
+        let tracing = trace::Supervisor::is_enabled();
+
         // Get the function arguments, and convert them to `libffi`-compatible form.
         let mut libffi_args = Vec::<CArg>::with_capacity(args.len());
         for arg in args.iter() {
@@ -213,12 +323,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // The first time this happens, print a warning.
                 if !this.machine.native_call_mem_warned.replace(true) {
                     // Newly set, so first time we get here.
-                    this.emit_diagnostic(NonHaltingDiagnostic::NativeCallSharedMem {
-                        //#[cfg(target_os = "linux")]
-                        //tracing: self::trace::Supervisor::is_enabled(),
-                        //#[cfg(not(target_os = "linux"))]
-                        tracing: false,
-                    });
+                    this.emit_diagnostic(NonHaltingDiagnostic::NativeCallSharedMem { tracing });
                 }
 
                 this.expose_provenance(prov)?;
@@ -245,15 +350,23 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             // be read by FFI. The `black_box` is defensive programming as LLVM likes
             // to (incorrectly) optimize away ptr2int casts whose result is unused.
             std::hint::black_box(alloc.get_bytes_unchecked_raw().expose_provenance());
-            // Expose all provenances in this allocation, since the native code can do $whatever.
-            for prov in alloc.provenance().provenances() {
-                this.expose_provenance(prov)?;
+
+            if !tracing {
+                // Expose all provenances in this allocation, since the native code can do $whatever.
+                // Can be skipped when tracing; in that case we'll expose just the actually-read parts later.
+                for prov in alloc.provenance().provenances() {
+                    this.expose_provenance(prov)?;
+                }
             }
 
             // Prepare for possible write from native code if mutable.
             if info.mutbl.is_mut() {
                 let (alloc, cx) = this.get_alloc_raw_mut(alloc_id)?;
-                alloc.process_native_write(&cx.tcx, None);
+                // These writes could initialize everything and wreck havoc with the pointers.
+                // We can skip that when tracing; in that case we'll later do that only for the memory that got actually written.
+                if !tracing {
+                    alloc.process_native_write(&cx.tcx, None);
+                }
                 // Also expose *mutable* provenance for the interpreter-level allocation.
                 std::hint::black_box(alloc.get_bytes_unchecked_raw_mut().expose_provenance());
             }
@@ -265,10 +378,8 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let (ret, maybe_memevents) =
             this.call_native_with_args(link_name, dest, code_ptr, libffi_args)?;
 
-        if cfg!(target_os = "linux")
-            && let Some(events) = maybe_memevents
-        {
-            trace!("Registered FFI events:\n{events:#0x?}");
+        if tracing {
+            this.tracing_apply_accesses(maybe_memevents.unwrap())?;
         }
 
         this.write_immediate(*ret, dest)?;
diff --git a/src/tools/miri/src/shims/native_lib/trace/child.rs b/src/tools/miri/src/shims/native_lib/trace/child.rs
index 4961e875c77..de26cb0fe55 100644
--- a/src/tools/miri/src/shims/native_lib/trace/child.rs
+++ b/src/tools/miri/src/shims/native_lib/trace/child.rs
@@ -4,12 +4,22 @@ use std::rc::Rc;
 use ipc_channel::ipc;
 use nix::sys::{ptrace, signal};
 use nix::unistd;
+use rustc_const_eval::interpret::InterpResult;
 
 use super::CALLBACK_STACK_SIZE;
-use super::messages::{Confirmation, MemEvents, StartFfiInfo, TraceRequest};
+use super::messages::{Confirmation, StartFfiInfo, TraceRequest};
 use super::parent::{ChildListener, sv_loop};
 use crate::alloc::isolated_alloc::IsolatedAlloc;
+use crate::shims::native_lib::MemEvents;
 
+/// A handle to the single, shared supervisor process across all `MiriMachine`s.
+/// Since it would be very difficult to trace multiple FFI calls in parallel, we
+/// need to ensure that either (a) only one `MiriMachine` is performing an FFI call
+/// at any given time, or (b) there are distinct supervisor and child processes for
+/// each machine. The former was chosen here.
+///
+/// This should only contain a `None` if the supervisor has not (yet) been initialised;
+/// otherwise, if `init_sv` was called and did not error, this will always be nonempty.
 static SUPERVISOR: std::sync::Mutex<Option<Supervisor>> = std::sync::Mutex::new(None);
 
 /// The main means of communication between the child and parent process,
@@ -34,32 +44,23 @@ impl Supervisor {
         SUPERVISOR.lock().unwrap().is_some()
     }
 
-    /// Begins preparations for doing an FFI call. This should be called at
-    /// the last possible moment before entering said call. `alloc` points to
-    /// the allocator which handed out the memory used for this machine.
-    ///
+    /// Performs an arbitrary FFI call, enabling tracing from the supervisor.
     /// As this locks the supervisor via a mutex, no other threads may enter FFI
-    /// until this one returns and its guard is dropped via `end_ffi`. The
-    /// pointer returned should be passed to `end_ffi` to avoid a memory leak.
-    ///
-    /// SAFETY: The resulting guard must be dropped *via `end_ffi`* immediately
-    /// after the desired call has concluded.
-    pub unsafe fn start_ffi(
+    /// until this function returns.
+    pub fn do_ffi<'tcx>(
         alloc: &Rc<RefCell<IsolatedAlloc>>,
-    ) -> (std::sync::MutexGuard<'static, Option<Supervisor>>, Option<*mut [u8; CALLBACK_STACK_SIZE]>)
-    {
+        f: impl FnOnce() -> InterpResult<'tcx, crate::ImmTy<'tcx>>,
+    ) -> InterpResult<'tcx, (crate::ImmTy<'tcx>, Option<MemEvents>)> {
         let mut sv_guard = SUPERVISOR.lock().unwrap();
-        // If the supervisor is not initialised for whatever reason, fast-fail.
-        // This might be desired behaviour, as even on platforms where ptracing
-        // is not implemented it enables us to enforce that only one FFI call
+        // If the supervisor is not initialised for whatever reason, fast-return.
+        // As a side-effect, even on platforms where ptracing
+        // is not implemented, we enforce that only one FFI call
         // happens at a time.
-        let Some(sv) = sv_guard.take() else {
-            return (sv_guard, None);
-        };
+        let Some(sv) = sv_guard.as_mut() else { return f().map(|v| (v, None)) };
 
         // Get pointers to all the pages the supervisor must allow accesses in
         // and prepare the callback stack.
-        let page_ptrs = alloc.borrow().pages();
+        let page_ptrs = alloc.borrow().pages().collect();
         let raw_stack_ptr: *mut [u8; CALLBACK_STACK_SIZE] =
             Box::leak(Box::new([0u8; CALLBACK_STACK_SIZE])).as_mut_ptr().cast();
         let stack_ptr = raw_stack_ptr.expose_provenance();
@@ -68,9 +69,9 @@ impl Supervisor {
         // SAFETY: We do not access machine memory past this point until the
         // supervisor is ready to allow it.
         unsafe {
-            if alloc.borrow_mut().prepare_ffi().is_err() {
+            if alloc.borrow_mut().start_ffi().is_err() {
                 // Don't mess up unwinding by maybe leaving the memory partly protected
-                alloc.borrow_mut().unprep_ffi();
+                alloc.borrow_mut().end_ffi();
                 panic!("Cannot protect memory for FFI call!");
             }
         }
@@ -82,27 +83,13 @@ impl Supervisor {
         // enforce an ordering for these events.
         sv.message_tx.send(TraceRequest::StartFfi(start_info)).unwrap();
         sv.confirm_rx.recv().unwrap();
-        *sv_guard = Some(sv);
         // We need to be stopped for the supervisor to be able to make certain
         // modifications to our memory - simply waiting on the recv() doesn't
         // count.
         signal::raise(signal::SIGSTOP).unwrap();
-        (sv_guard, Some(raw_stack_ptr))
-    }
 
-    /// Undoes FFI-related preparations, allowing Miri to continue as normal, then
-    /// gets the memory accesses and changes performed during the FFI call. Note
-    /// that this may include some spurious accesses done by `libffi` itself in
-    /// the process of executing the function call.
-    ///
-    /// SAFETY: The `sv_guard` and `raw_stack_ptr` passed must be the same ones
-    /// received by a prior call to `start_ffi`, and the allocator must be the
-    /// one passed to it also.
-    pub unsafe fn end_ffi(
-        alloc: &Rc<RefCell<IsolatedAlloc>>,
-        mut sv_guard: std::sync::MutexGuard<'static, Option<Supervisor>>,
-        raw_stack_ptr: Option<*mut [u8; CALLBACK_STACK_SIZE]>,
-    ) -> Option<MemEvents> {
+        let res = f();
+
         // We can't use IPC channels here to signal that FFI mode has ended,
         // since they might allocate memory which could get us stuck in a SIGTRAP
         // with no easy way out! While this could be worked around, it is much
@@ -113,42 +100,40 @@ impl Supervisor {
         signal::raise(signal::SIGUSR1).unwrap();
 
         // This is safe! It just sets memory to normal expected permissions.
-        alloc.borrow_mut().unprep_ffi();
+        alloc.borrow_mut().end_ffi();
 
-        // If this is `None`, then `raw_stack_ptr` is None and does not need to
-        // be deallocated (and there's no need to worry about the guard, since
-        // it contains nothing).
-        let sv = sv_guard.take()?;
         // SAFETY: Caller upholds that this pointer was allocated as a box with
         // this type.
         unsafe {
-            drop(Box::from_raw(raw_stack_ptr.unwrap()));
+            drop(Box::from_raw(raw_stack_ptr));
         }
         // On the off-chance something really weird happens, don't block forever.
-        let ret = sv
+        let events = sv
             .event_rx
             .try_recv_timeout(std::time::Duration::from_secs(5))
             .map_err(|e| {
                 match e {
                     ipc::TryRecvError::IpcError(_) => (),
                     ipc::TryRecvError::Empty =>
-                        eprintln!("Waiting for accesses from supervisor timed out!"),
+                        panic!("Waiting for accesses from supervisor timed out!"),
                 }
             })
             .ok();
-        // Do *not* leave the supervisor empty, or else we might get another fork...
-        *sv_guard = Some(sv);
-        ret
+
+        res.map(|v| (v, events))
     }
 }
 
 /// Initialises the supervisor process. If this function errors, then the
 /// supervisor process could not be created successfully; else, the caller
-/// is now the child process and can communicate via `start_ffi`/`end_ffi`,
-/// receiving back events through `get_events`.
+/// is now the child process and can communicate via `do_ffi`, receiving back
+/// events at the end.
 ///
 /// # Safety
-/// The invariants for `fork()` must be upheld by the caller.
+/// The invariants for `fork()` must be upheld by the caller, namely either:
+/// - Other threads do not exist, or;
+/// - If they do exist, either those threads or the resulting child process
+///   only ever act in [async-signal-safe](https://www.man7.org/linux/man-pages/man7/signal-safety.7.html) ways.
 pub unsafe fn init_sv() -> Result<(), SvInitError> {
     // FIXME: Much of this could be reimplemented via the mitosis crate if we upstream the
     // relevant missing bits.
@@ -191,8 +176,7 @@ pub unsafe fn init_sv() -> Result<(), SvInitError> {
                 // The child process is free to unwind, so we won't to avoid doubly freeing
                 // system resources.
                 let init = std::panic::catch_unwind(|| {
-                    let listener =
-                        ChildListener { message_rx, attached: false, override_retcode: None };
+                    let listener = ChildListener::new(message_rx, confirm_tx.clone());
                     // Trace as many things as possible, to be able to handle them as needed.
                     let options = ptrace::Options::PTRACE_O_TRACESYSGOOD
                         | ptrace::Options::PTRACE_O_TRACECLONE
@@ -218,7 +202,9 @@ pub unsafe fn init_sv() -> Result<(), SvInitError> {
                     // The "Ok" case means that we couldn't ptrace.
                     Ok(e) => return Err(e),
                     Err(p) => {
-                        eprintln!("Supervisor process panicked!\n{p:?}");
+                        eprintln!(
+                            "Supervisor process panicked!\n{p:?}\n\nTry running again without using the native-lib tracer."
+                        );
                         std::process::exit(1);
                     }
                 }
@@ -239,13 +225,11 @@ pub unsafe fn init_sv() -> Result<(), SvInitError> {
 }
 
 /// Instruct the supervisor process to return a particular code. Useful if for
-/// whatever reason this code fails to be intercepted normally. In the case of
-/// `abort_if_errors()` used in `bin/miri.rs`, the return code is erroneously
-/// given as a 0 if this is not used.
+/// whatever reason this code fails to be intercepted normally.
 pub fn register_retcode_sv(code: i32) {
     let mut sv_guard = SUPERVISOR.lock().unwrap();
-    if let Some(sv) = sv_guard.take() {
+    if let Some(sv) = sv_guard.as_mut() {
         sv.message_tx.send(TraceRequest::OverrideRetcode(code)).unwrap();
-        *sv_guard = Some(sv);
+        sv.confirm_rx.recv().unwrap();
     }
 }
diff --git a/src/tools/miri/src/shims/native_lib/trace/messages.rs b/src/tools/miri/src/shims/native_lib/trace/messages.rs
index 8a83dab5c09..1f9df556b57 100644
--- a/src/tools/miri/src/shims/native_lib/trace/messages.rs
+++ b/src/tools/miri/src/shims/native_lib/trace/messages.rs
@@ -1,25 +1,28 @@
 //! Houses the types that are directly sent across the IPC channels.
 //!
-//! The overall structure of a traced FFI call, from the child process's POV, is
-//! as follows:
+//! When forking to initialise the supervisor during `init_sv`, the child raises
+//! a `SIGSTOP`; if the parent successfully ptraces the child, it will allow it
+//! to resume. Else, the child will be killed by the parent.
+//!
+//! After initialisation is done, the overall structure of a traced FFI call from
+//! the child process's POV is as follows:
 //! ```
 //! message_tx.send(TraceRequest::StartFfi);
-//! confirm_rx.recv();
+//! confirm_rx.recv(); // receives a `Confirmation`
 //! raise(SIGSTOP);
 //! /* do ffi call */
 //! raise(SIGUSR1); // morally equivalent to some kind of "TraceRequest::EndFfi"
-//! let events = event_rx.recv();
+//! let events = event_rx.recv(); // receives a `MemEvents`
 //! ```
 //! `TraceRequest::OverrideRetcode` can be sent at any point in the above, including
-//! before or after all of them.
+//! before or after all of them. `confirm_rx.recv()` is to be called after, to ensure
+//! that the child does not exit before the supervisor has registered the return code.
 //!
 //! NB: sending these events out of order, skipping steps, etc. will result in
 //! unspecified behaviour from the supervisor process, so use the abstractions
-//! in `super::child` (namely `start_ffi()` and `end_ffi()`) to handle this. It is
+//! in `super::child` (namely `do_ffi()`) to handle this. It is
 //! trivially easy to cause a deadlock or crash by messing this up!
 
-use std::ops::Range;
-
 /// An IPC request sent by the child process to the parent.
 ///
 /// The sender for this channel should live on the child process.
@@ -34,6 +37,8 @@ pub enum TraceRequest {
     StartFfi(StartFfiInfo),
     /// Manually overrides the code that the supervisor will return upon exiting.
     /// Once set, it is permanent. This can be called again to change the value.
+    ///
+    /// After sending this, the child must wait to receive a `Confirmation`.
     OverrideRetcode(i32),
 }
 
@@ -41,7 +46,7 @@ pub enum TraceRequest {
 #[derive(serde::Serialize, serde::Deserialize, Debug, Clone)]
 pub struct StartFfiInfo {
     /// A vector of page addresses. These should have been automatically obtained
-    /// with `IsolatedAlloc::pages` and prepared with `IsolatedAlloc::prepare_ffi`.
+    /// with `IsolatedAlloc::pages` and prepared with `IsolatedAlloc::start_ffi`.
     pub page_ptrs: Vec<usize>,
     /// The address of an allocation that can serve as a temporary stack.
     /// This should be a leaked `Box<[u8; CALLBACK_STACK_SIZE]>` cast to an int.
@@ -54,27 +59,3 @@ pub struct StartFfiInfo {
 /// The sender for this channel should live on the parent process.
 #[derive(serde::Serialize, serde::Deserialize, Debug)]
 pub struct Confirmation;
-
-/// The final results of an FFI trace, containing every relevant event detected
-/// by the tracer. Sent by the supervisor after receiving a `SIGUSR1` signal.
-///
-/// The sender for this channel should live on the parent process.
-#[derive(serde::Serialize, serde::Deserialize, Debug)]
-pub struct MemEvents {
-    /// An ordered list of memory accesses that occurred. These should be assumed
-    /// to be overcautious; that is, if the size of an access is uncertain it is
-    /// pessimistically rounded up, and if the type (read/write/both) is uncertain
-    /// it is reported as whatever would be safest to assume; i.e. a read + maybe-write
-    /// becomes a read + write, etc.
-    pub acc_events: Vec<AccessEvent>,
-}
-
-/// A single memory access, conservatively overestimated
-/// in case of ambiguity.
-#[derive(serde::Serialize, serde::Deserialize, Debug)]
-pub enum AccessEvent {
-    /// A read may have occurred on no more than the specified address range.
-    Read(Range<usize>),
-    /// A write may have occurred on no more than the specified address range.
-    Write(Range<usize>),
-}
diff --git a/src/tools/miri/src/shims/native_lib/trace/mod.rs b/src/tools/miri/src/shims/native_lib/trace/mod.rs
index 174b06b3ac5..c8abacfb5e2 100644
--- a/src/tools/miri/src/shims/native_lib/trace/mod.rs
+++ b/src/tools/miri/src/shims/native_lib/trace/mod.rs
@@ -5,4 +5,6 @@ mod parent;
 pub use self::child::{Supervisor, init_sv, register_retcode_sv};
 
 /// The size of the temporary stack we use for callbacks that the server executes in the client.
+/// This should be big enough that `mempr_on` and `mempr_off` can safely be jumped into with the
+/// stack pointer pointing to a "stack" of this size without overflowing it.
 const CALLBACK_STACK_SIZE: usize = 1024;
diff --git a/src/tools/miri/src/shims/native_lib/trace/parent.rs b/src/tools/miri/src/shims/native_lib/trace/parent.rs
index dfb0b35da69..83f6c7a13fc 100644
--- a/src/tools/miri/src/shims/native_lib/trace/parent.rs
+++ b/src/tools/miri/src/shims/native_lib/trace/parent.rs
@@ -5,26 +5,17 @@ use nix::sys::{ptrace, signal, wait};
 use nix::unistd;
 
 use super::CALLBACK_STACK_SIZE;
-use super::messages::{AccessEvent, Confirmation, MemEvents, StartFfiInfo, TraceRequest};
+use super::messages::{Confirmation, StartFfiInfo, TraceRequest};
+use crate::shims::native_lib::{AccessEvent, AccessRange, MemEvents};
 
 /// The flags to use when calling `waitid()`.
-/// Since bitwise or on the nix version of these flags is implemented as a trait,
-/// this cannot be const directly so we do it this way.
 const WAIT_FLAGS: wait::WaitPidFlag =
-    wait::WaitPidFlag::from_bits_truncate(libc::WUNTRACED | libc::WEXITED);
-
-/// Arch-specific maximum size a single access might perform. x86 value is set
-/// assuming nothing bigger than AVX-512 is available.
-#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
-const ARCH_MAX_ACCESS_SIZE: usize = 64;
-/// The largest arm64 simd instruction operates on 16 bytes.
-#[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
-const ARCH_MAX_ACCESS_SIZE: usize = 16;
+    wait::WaitPidFlag::WUNTRACED.union(wait::WaitPidFlag::WEXITED);
 
 /// The default word size on a given platform, in bytes.
-#[cfg(any(target_arch = "x86", target_arch = "arm"))]
+#[cfg(target_arch = "x86")]
 const ARCH_WORD_SIZE: usize = 4;
-#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
+#[cfg(target_arch = "x86_64")]
 const ARCH_WORD_SIZE: usize = 8;
 
 /// The address of the page set to be edited, initialised to a sentinel null
@@ -53,39 +44,25 @@ trait ArchIndependentRegs {
 // It's fine / desirable behaviour for values to wrap here, we care about just
 // preserving the bit pattern.
 #[cfg(target_arch = "x86_64")]
-#[expect(clippy::as_conversions)]
 #[rustfmt::skip]
 impl ArchIndependentRegs for libc::user_regs_struct {
     #[inline]
-    fn ip(&self) -> usize { self.rip as _ }
+    fn ip(&self) -> usize { self.rip.try_into().unwrap() }
     #[inline]
-    fn set_ip(&mut self, ip: usize) { self.rip = ip as _ }
+    fn set_ip(&mut self, ip: usize) { self.rip = ip.try_into().unwrap() }
     #[inline]
-    fn set_sp(&mut self, sp: usize) { self.rsp = sp as _ }
+    fn set_sp(&mut self, sp: usize) { self.rsp = sp.try_into().unwrap() }
 }
 
 #[cfg(target_arch = "x86")]
-#[expect(clippy::as_conversions)]
 #[rustfmt::skip]
 impl ArchIndependentRegs for libc::user_regs_struct {
     #[inline]
-    fn ip(&self) -> usize { self.eip as _ }
+    fn ip(&self) -> usize { self.eip.cast_unsigned().try_into().unwrap() }
     #[inline]
-    fn set_ip(&mut self, ip: usize) { self.eip = ip as _ }
+    fn set_ip(&mut self, ip: usize) { self.eip = ip.cast_signed().try_into().unwrap() }
     #[inline]
-    fn set_sp(&mut self, sp: usize) { self.esp = sp as _ }
-}
-
-#[cfg(target_arch = "aarch64")]
-#[expect(clippy::as_conversions)]
-#[rustfmt::skip]
-impl ArchIndependentRegs for libc::user_regs_struct {
-    #[inline]
-    fn ip(&self) -> usize { self.pc as _ }
-    #[inline]
-    fn set_ip(&mut self, ip: usize) { self.pc = ip as _ }
-    #[inline]
-    fn set_sp(&mut self, sp: usize) { self.sp = sp as _ }
+    fn set_sp(&mut self, sp: usize) { self.esp = sp.cast_signed().try_into().unwrap() }
 }
 
 /// A unified event representing something happening on the child process. Wraps
@@ -109,11 +86,24 @@ pub enum ExecEvent {
 /// A listener for the FFI start info channel along with relevant state.
 pub struct ChildListener {
     /// The matching channel for the child's `Supervisor` struct.
-    pub message_rx: ipc::IpcReceiver<TraceRequest>,
+    message_rx: ipc::IpcReceiver<TraceRequest>,
+    /// ...
+    confirm_tx: ipc::IpcSender<Confirmation>,
     /// Whether an FFI call is currently ongoing.
-    pub attached: bool,
+    attached: bool,
     /// If `Some`, overrides the return code with the given value.
-    pub override_retcode: Option<i32>,
+    override_retcode: Option<i32>,
+    /// Last code obtained from a child exiting.
+    last_code: Option<i32>,
+}
+
+impl ChildListener {
+    pub fn new(
+        message_rx: ipc::IpcReceiver<TraceRequest>,
+        confirm_tx: ipc::IpcSender<Confirmation>,
+    ) -> Self {
+        Self { message_rx, confirm_tx, attached: false, override_retcode: None, last_code: None }
+    }
 }
 
 impl Iterator for ChildListener {
@@ -133,16 +123,10 @@ impl Iterator for ChildListener {
                 Ok(stat) =>
                     match stat {
                         // Child exited normally with a specific code set.
-                        wait::WaitStatus::Exited(_, code) => {
-                            let code = self.override_retcode.unwrap_or(code);
-                            return Some(ExecEvent::Died(Some(code)));
-                        }
+                        wait::WaitStatus::Exited(_, code) => self.last_code = Some(code),
                         // Child was killed by a signal, without giving a code.
-                        wait::WaitStatus::Signaled(_, _, _) =>
-                            return Some(ExecEvent::Died(self.override_retcode)),
-                        // Child entered a syscall. Since we're always technically
-                        // tracing, only pass this along if we're actively
-                        // monitoring the child.
+                        wait::WaitStatus::Signaled(_, _, _) => self.last_code = None,
+                        // Child entered or exited a syscall.
                         wait::WaitStatus::PtraceSyscall(pid) =>
                             if self.attached {
                                 return Some(ExecEvent::Syscall(pid));
@@ -179,10 +163,8 @@ impl Iterator for ChildListener {
                             },
                         _ => (),
                     },
-                // This case should only trigger if all children died and we
-                // somehow missed that, but it's best we not allow any room
-                // for deadlocks.
-                Err(_) => return Some(ExecEvent::Died(None)),
+                // This case should only trigger when all children died.
+                Err(_) => return Some(ExecEvent::Died(self.override_retcode.or(self.last_code))),
             }
 
             // Similarly, do a non-blocking poll of the IPC channel.
@@ -196,7 +178,10 @@ impl Iterator for ChildListener {
                             self.attached = true;
                             return Some(ExecEvent::Start(info));
                         },
-                    TraceRequest::OverrideRetcode(code) => self.override_retcode = Some(code),
+                    TraceRequest::OverrideRetcode(code) => {
+                        self.override_retcode = Some(code);
+                        self.confirm_tx.send(Confirmation).unwrap();
+                    }
                 }
             }
 
@@ -211,6 +196,12 @@ impl Iterator for ChildListener {
 #[derive(Debug)]
 pub struct ExecEnd(pub Option<i32>);
 
+/// Whether to call `ptrace::cont()` immediately. Used exclusively by `wait_for_signal`.
+enum InitialCont {
+    Yes,
+    No,
+}
+
 /// This is the main loop of the supervisor process. It runs in a separate
 /// process from the rest of Miri (but because we fork, addresses for anything
 /// created before the fork - like statics - are the same).
@@ -239,12 +230,12 @@ pub fn sv_loop(
     let mut curr_pid = init_pid;
 
     // There's an initial sigstop we need to deal with.
-    wait_for_signal(Some(curr_pid), signal::SIGSTOP, false)?;
+    wait_for_signal(Some(curr_pid), signal::SIGSTOP, InitialCont::No)?;
     ptrace::cont(curr_pid, None).unwrap();
 
     for evt in listener {
         match evt {
-            // start_ffi was called by the child, so prep memory.
+            // Child started ffi, so prep memory.
             ExecEvent::Start(ch_info) => {
                 // All the pages that the child process is "allowed to" access.
                 ch_pages = ch_info.page_ptrs;
@@ -252,17 +243,17 @@ pub fn sv_loop(
                 ch_stack = Some(ch_info.stack_ptr);
 
                 // We received the signal and are no longer in the main listener loop,
-                // so we can let the child move on to the end of start_ffi where it will
+                // so we can let the child move on to the end of the ffi prep where it will
                 // raise a SIGSTOP. We need it to be signal-stopped *and waited for* in
                 // order to do most ptrace operations!
                 confirm_tx.send(Confirmation).unwrap();
                 // We can't trust simply calling `Pid::this()` in the child process to give the right
                 // PID for us, so we get it this way.
-                curr_pid = wait_for_signal(None, signal::SIGSTOP, false).unwrap();
+                curr_pid = wait_for_signal(None, signal::SIGSTOP, InitialCont::No).unwrap();
 
                 ptrace::syscall(curr_pid, None).unwrap();
             }
-            // end_ffi was called by the child.
+            // Child wants to end tracing.
             ExecEvent::End => {
                 // Hand over the access info we traced.
                 event_tx.send(MemEvents { acc_events }).unwrap();
@@ -322,10 +313,6 @@ fn get_disasm() -> capstone::Capstone {
         {cs_pre.x86().mode(arch::x86::ArchMode::Mode64)}
         #[cfg(target_arch = "x86")]
         {cs_pre.x86().mode(arch::x86::ArchMode::Mode32)}
-        #[cfg(target_arch = "aarch64")]
-        {cs_pre.arm64().mode(arch::arm64::ArchMode::Arm)}
-        #[cfg(target_arch = "arm")]
-        {cs_pre.arm().mode(arch::arm::ArchMode::Arm)}
     }
     .detail(true)
     .build()
@@ -339,9 +326,9 @@ fn get_disasm() -> capstone::Capstone {
 fn wait_for_signal(
     pid: Option<unistd::Pid>,
     wait_signal: signal::Signal,
-    init_cont: bool,
+    init_cont: InitialCont,
 ) -> Result<unistd::Pid, ExecEnd> {
-    if init_cont {
+    if matches!(init_cont, InitialCont::Yes) {
         ptrace::cont(pid.unwrap(), None).unwrap();
     }
     // Repeatedly call `waitid` until we get the signal we want, or the process dies.
@@ -374,6 +361,84 @@ fn wait_for_signal(
     }
 }
 
+/// Add the memory events from `op` being executed while there is a memory access at `addr` to
+/// `acc_events`. Return whether this was a memory operand.
+fn capstone_find_events(
+    addr: usize,
+    op: &capstone::arch::ArchOperand,
+    acc_events: &mut Vec<AccessEvent>,
+) -> bool {
+    use capstone::prelude::*;
+    match op {
+        #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+        arch::ArchOperand::X86Operand(x86_operand) => {
+            match x86_operand.op_type {
+                // We only care about memory accesses
+                arch::x86::X86OperandType::Mem(_) => {
+                    let push = AccessRange { addr, size: x86_operand.size.into() };
+                    // It's called a "RegAccessType" but it also applies to memory
+                    let acc_ty = x86_operand.access.unwrap();
+                    // The same instruction might do both reads and writes, so potentially add both.
+                    // We do not know the order in which they happened, but writing and then reading
+                    // makes little sense so we put the read first. That is also the more
+                    // conservative choice.
+                    if acc_ty.is_readable() {
+                        acc_events.push(AccessEvent::Read(push.clone()));
+                    }
+                    if acc_ty.is_writable() {
+                        // FIXME: This could be made certain; either determine all cases where
+                        // only reads happen, or have an intermediate mempr_* function to first
+                        // map the page(s) as readonly and check if a segfault occurred.
+
+                        // Per https://docs.rs/iced-x86/latest/iced_x86/enum.OpAccess.html,
+                        // we know that the possible access types are Read, CondRead, Write,
+                        // CondWrite, ReadWrite, and ReadCondWrite. Since we got a segfault
+                        // we know some kind of access happened so Cond{Read, Write}s are
+                        // certain reads and writes; the only uncertainty is with an RW op
+                        // as it might be a ReadCondWrite with the write condition unmet.
+                        acc_events.push(AccessEvent::Write(push, !acc_ty.is_readable()));
+                    }
+
+                    return true;
+                }
+                _ => (),
+            }
+        }
+        // FIXME: arm64
+        _ => unimplemented!(),
+    }
+
+    false
+}
+
+/// Extract the events from the given instruction.
+fn capstone_disassemble(
+    instr: &[u8],
+    addr: usize,
+    cs: &capstone::Capstone,
+    acc_events: &mut Vec<AccessEvent>,
+) -> capstone::CsResult<()> {
+    // The arch_detail is what we care about, but it relies on these temporaries
+    // that we can't drop. 0x1000 is the default base address for Captsone, and
+    // we're expecting 1 instruction.
+    let insns = cs.disasm_count(instr, 0x1000, 1)?;
+    let ins_detail = cs.insn_detail(&insns[0])?;
+    let arch_detail = ins_detail.arch_detail();
+
+    let mut found_mem_op = false;
+
+    for op in arch_detail.operands() {
+        if capstone_find_events(addr, &op, acc_events) {
+            if found_mem_op {
+                panic!("more than one memory operand found; we don't know which one accessed what");
+            }
+            found_mem_op = true;
+        }
+    }
+
+    Ok(())
+}
+
 /// Grabs the access that caused a segfault and logs it down if it's to our memory,
 /// or kills the child and returns the appropriate error otherwise.
 fn handle_segfault(
@@ -384,116 +449,10 @@ fn handle_segfault(
     cs: &capstone::Capstone,
     acc_events: &mut Vec<AccessEvent>,
 ) -> Result<(), ExecEnd> {
-    /// This is just here to not pollute the main namespace with `capstone::prelude::*`.
-    #[inline]
-    fn capstone_disassemble(
-        instr: &[u8],
-        addr: usize,
-        cs: &capstone::Capstone,
-        acc_events: &mut Vec<AccessEvent>,
-    ) -> capstone::CsResult<()> {
-        use capstone::prelude::*;
-
-        // The arch_detail is what we care about, but it relies on these temporaries
-        // that we can't drop. 0x1000 is the default base address for Captsone, and
-        // we're expecting 1 instruction.
-        let insns = cs.disasm_count(instr, 0x1000, 1)?;
-        let ins_detail = cs.insn_detail(&insns[0])?;
-        let arch_detail = ins_detail.arch_detail();
-
-        for op in arch_detail.operands() {
-            match op {
-                #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
-                arch::ArchOperand::X86Operand(x86_operand) => {
-                    match x86_operand.op_type {
-                        // We only care about memory accesses
-                        arch::x86::X86OperandType::Mem(_) => {
-                            let push = addr..addr.strict_add(usize::from(x86_operand.size));
-                            // It's called a "RegAccessType" but it also applies to memory
-                            let acc_ty = x86_operand.access.unwrap();
-                            if acc_ty.is_readable() {
-                                acc_events.push(AccessEvent::Read(push.clone()));
-                            }
-                            if acc_ty.is_writable() {
-                                acc_events.push(AccessEvent::Write(push));
-                            }
-                        }
-                        _ => (),
-                    }
-                }
-                #[cfg(target_arch = "aarch64")]
-                arch::ArchOperand::Arm64Operand(arm64_operand) => {
-                    // Annoyingly, we don't always get the size here, so just be pessimistic for now.
-                    match arm64_operand.op_type {
-                        arch::arm64::Arm64OperandType::Mem(_) => {
-                            // B = 1 byte, H = 2 bytes, S = 4 bytes, D = 8 bytes, Q = 16 bytes.
-                            let size = match arm64_operand.vas {
-                                // Not an fp/simd instruction.
-                                arch::arm64::Arm64Vas::ARM64_VAS_INVALID => ARCH_WORD_SIZE,
-                                // 1 byte.
-                                arch::arm64::Arm64Vas::ARM64_VAS_1B => 1,
-                                // 2 bytes.
-                                arch::arm64::Arm64Vas::ARM64_VAS_1H => 2,
-                                // 4 bytes.
-                                arch::arm64::Arm64Vas::ARM64_VAS_4B
-                                | arch::arm64::Arm64Vas::ARM64_VAS_2H
-                                | arch::arm64::Arm64Vas::ARM64_VAS_1S => 4,
-                                // 8 bytes.
-                                arch::arm64::Arm64Vas::ARM64_VAS_8B
-                                | arch::arm64::Arm64Vas::ARM64_VAS_4H
-                                | arch::arm64::Arm64Vas::ARM64_VAS_2S
-                                | arch::arm64::Arm64Vas::ARM64_VAS_1D => 8,
-                                // 16 bytes.
-                                arch::arm64::Arm64Vas::ARM64_VAS_16B
-                                | arch::arm64::Arm64Vas::ARM64_VAS_8H
-                                | arch::arm64::Arm64Vas::ARM64_VAS_4S
-                                | arch::arm64::Arm64Vas::ARM64_VAS_2D
-                                | arch::arm64::Arm64Vas::ARM64_VAS_1Q => 16,
-                            };
-                            let push = addr..addr.strict_add(size);
-                            // FIXME: This now has access type info in the latest
-                            // git version of capstone because this pissed me off
-                            // and I added it. Change this when it updates.
-                            acc_events.push(AccessEvent::Read(push.clone()));
-                            acc_events.push(AccessEvent::Write(push));
-                        }
-                        _ => (),
-                    }
-                }
-                #[cfg(target_arch = "arm")]
-                arch::ArchOperand::ArmOperand(arm_operand) =>
-                    match arm_operand.op_type {
-                        arch::arm::ArmOperandType::Mem(_) => {
-                            // We don't get info on the size of the access, but
-                            // we're at least told if it's a vector instruction.
-                            let size = if arm_operand.vector_index.is_some() {
-                                ARCH_MAX_ACCESS_SIZE
-                            } else {
-                                ARCH_WORD_SIZE
-                            };
-                            let push = addr..addr.strict_add(size);
-                            let acc_ty = arm_operand.access.unwrap();
-                            if acc_ty.is_readable() {
-                                acc_events.push(AccessEvent::Read(push.clone()));
-                            }
-                            if acc_ty.is_writable() {
-                                acc_events.push(AccessEvent::Write(push));
-                            }
-                        }
-                        _ => (),
-                    },
-                _ => unimplemented!(),
-            }
-        }
-
-        Ok(())
-    }
-
     // Get information on what caused the segfault. This contains the address
     // that triggered it.
     let siginfo = ptrace::getsiginfo(pid).unwrap();
-    // All x86, ARM, etc. instructions only have at most one memory operand
-    // (thankfully!)
+    // All x86 instructions only have at most one memory operand (thankfully!)
     // SAFETY: si_addr is safe to call.
     let addr = unsafe { siginfo.si_addr().addr() };
     let page_addr = addr.strict_sub(addr.strict_rem(page_size));
@@ -515,7 +474,7 @@ fn handle_segfault(
     //   global atomic variables. This is what we use the temporary callback stack for.
     // - Step 1 instruction
     // - Parse executed code to estimate size & type of access
-    // - Reprotect the memory by executing `mempr_on` in the child.
+    // - Reprotect the memory by executing `mempr_on` in the child, using the callback stack again.
     // - Continue
 
     // Ensure the stack is properly zeroed out!
@@ -540,7 +499,7 @@ fn handle_segfault(
     ptrace::write(
         pid,
         (&raw const PAGE_ADDR).cast_mut().cast(),
-        libc::c_long::try_from(page_addr).unwrap(),
+        libc::c_long::try_from(page_addr.cast_signed()).unwrap(),
     )
     .unwrap();
 
@@ -552,7 +511,7 @@ fn handle_segfault(
     ptrace::setregs(pid, new_regs).unwrap();
 
     // Our mempr_* functions end with a raise(SIGSTOP).
-    wait_for_signal(Some(pid), signal::SIGSTOP, true)?;
+    wait_for_signal(Some(pid), signal::SIGSTOP, InitialCont::Yes)?;
 
     // Step 1 instruction.
     ptrace::setregs(pid, regs_bak).unwrap();
@@ -573,6 +532,12 @@ fn handle_segfault(
     let regs_bak = ptrace::getregs(pid).unwrap();
     new_regs = regs_bak;
     let ip_poststep = regs_bak.ip();
+
+    // Ensure that we've actually gone forwards.
+    assert!(ip_poststep > ip_prestep);
+    // But not by too much. 64 bytes should be "big enough" on ~any architecture.
+    assert!(ip_prestep.strict_add(64) > ip_poststep);
+
     // We need to do reads/writes in word-sized chunks.
     let diff = (ip_poststep.strict_sub(ip_prestep)).div_ceil(ARCH_WORD_SIZE);
     let instr = (ip_prestep..ip_prestep.strict_add(diff)).fold(vec![], |mut ret, ip| {
@@ -587,20 +552,14 @@ fn handle_segfault(
     });
 
     // Now figure out the size + type of access and log it down.
-    // This will mark down e.g. the same area being read multiple times,
-    // since it's more efficient to compress the accesses at the end.
-    if capstone_disassemble(&instr, addr, cs, acc_events).is_err() {
-        // Read goes first because we need to be pessimistic.
-        acc_events.push(AccessEvent::Read(addr..addr.strict_add(ARCH_MAX_ACCESS_SIZE)));
-        acc_events.push(AccessEvent::Write(addr..addr.strict_add(ARCH_MAX_ACCESS_SIZE)));
-    }
+    capstone_disassemble(&instr, addr, cs, acc_events).expect("Failed to disassemble instruction");
 
     // Reprotect everything and continue.
     #[expect(clippy::as_conversions)]
     new_regs.set_ip(mempr_on as usize);
     new_regs.set_sp(stack_ptr);
     ptrace::setregs(pid, new_regs).unwrap();
-    wait_for_signal(Some(pid), signal::SIGSTOP, true)?;
+    wait_for_signal(Some(pid), signal::SIGSTOP, InitialCont::Yes)?;
 
     ptrace::setregs(pid, regs_bak).unwrap();
     ptrace::syscall(pid, None).unwrap();
diff --git a/src/tools/miri/src/shims/native_lib/trace/stub.rs b/src/tools/miri/src/shims/native_lib/trace/stub.rs
new file mode 100644
index 00000000000..22787a6f6fa
--- /dev/null
+++ b/src/tools/miri/src/shims/native_lib/trace/stub.rs
@@ -0,0 +1,34 @@
+use rustc_const_eval::interpret::InterpResult;
+
+static SUPERVISOR: std::sync::Mutex<()> = std::sync::Mutex::new(());
+
+pub struct Supervisor;
+
+#[derive(Debug)]
+pub struct SvInitError;
+
+impl Supervisor {
+    #[inline(always)]
+    pub fn is_enabled() -> bool {
+        false
+    }
+
+    pub fn do_ffi<'tcx, T>(
+        _: T,
+        f: impl FnOnce() -> InterpResult<'tcx, crate::ImmTy<'tcx>>,
+    ) -> InterpResult<'tcx, (crate::ImmTy<'tcx>, Option<super::MemEvents>)> {
+        // We acquire the lock to ensure that no two FFI calls run concurrently.
+        let _g = SUPERVISOR.lock().unwrap();
+        f().map(|v| (v, None))
+    }
+}
+
+#[inline(always)]
+#[allow(dead_code, clippy::missing_safety_doc)]
+pub unsafe fn init_sv() -> Result<!, SvInitError> {
+    Err(SvInitError)
+}
+
+#[inline(always)]
+#[allow(dead_code)]
+pub fn register_retcode_sv<T>(_: T) {}
diff --git a/src/tools/miri/src/shims/panic.rs b/src/tools/miri/src/shims/panic.rs
index 9490761d0c9..85564e47685 100644
--- a/src/tools/miri/src/shims/panic.rs
+++ b/src/tools/miri/src/shims/panic.rs
@@ -1,162 +1,12 @@
-//! Panic runtime for Miri.
-//!
-//! The core pieces of the runtime are:
-//! - An implementation of `__rust_maybe_catch_panic` that pushes the invoked stack frame with
-//!   some extra metadata derived from the panic-catching arguments of `__rust_maybe_catch_panic`.
-//! - A hack in `libpanic_unwind` that calls the `miri_start_unwind` intrinsic instead of the
-//!   target-native panic runtime. (This lives in the rustc repo.)
-//! - An implementation of `miri_start_unwind` that stores its argument (the panic payload), and then
-//!   immediately returns, but on the *unwind* edge (not the normal return edge), thus initiating unwinding.
-//! - A hook executed each time a frame is popped, such that if the frame pushed by `__rust_maybe_catch_panic`
-//!   gets popped *during unwinding*, we take the panic payload and store it according to the extra
-//!   metadata we remembered when pushing said frame.
+//! Helper functions for causing panics.
 
 use rustc_abi::ExternAbi;
 use rustc_middle::{mir, ty};
-use rustc_target::spec::PanicStrategy;
 
-use self::helpers::check_intrinsic_arg_count;
 use crate::*;
 
-/// Holds all of the relevant data for when unwinding hits a `try` frame.
-#[derive(Debug)]
-pub struct CatchUnwindData<'tcx> {
-    /// The `catch_fn` callback to call in case of a panic.
-    catch_fn: Pointer,
-    /// The `data` argument for that callback.
-    data: ImmTy<'tcx>,
-    /// The return place from the original call to `try`.
-    dest: MPlaceTy<'tcx>,
-    /// The return block from the original call to `try`.
-    ret: Option<mir::BasicBlock>,
-}
-
-impl VisitProvenance for CatchUnwindData<'_> {
-    fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
-        let CatchUnwindData { catch_fn, data, dest, ret: _ } = self;
-        catch_fn.visit_provenance(visit);
-        data.visit_provenance(visit);
-        dest.visit_provenance(visit);
-    }
-}
-
 impl<'tcx> EvalContextExt<'tcx> for crate::MiriInterpCx<'tcx> {}
 pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
-    /// Handles the special `miri_start_unwind` intrinsic, which is called
-    /// by libpanic_unwind to delegate the actual unwinding process to Miri.
-    fn handle_miri_start_unwind(&mut self, payload: &OpTy<'tcx>) -> InterpResult<'tcx> {
-        let this = self.eval_context_mut();
-
-        trace!("miri_start_unwind: {:?}", this.frame().instance());
-
-        let payload = this.read_immediate(payload)?;
-        let thread = this.active_thread_mut();
-        thread.panic_payloads.push(payload);
-
-        interp_ok(())
-    }
-
-    /// Handles the `catch_unwind` intrinsic.
-    fn handle_catch_unwind(
-        &mut self,
-        args: &[OpTy<'tcx>],
-        dest: &MPlaceTy<'tcx>,
-        ret: Option<mir::BasicBlock>,
-    ) -> InterpResult<'tcx> {
-        let this = self.eval_context_mut();
-
-        // Signature:
-        //   fn catch_unwind(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32
-        // Calls `try_fn` with `data` as argument. If that executes normally, returns 0.
-        // If that unwinds, calls `catch_fn` with the first argument being `data` and
-        // then second argument being a target-dependent `payload` (i.e. it is up to us to define
-        // what that is), and returns 1.
-        // The `payload` is passed (by libstd) to `__rust_panic_cleanup`, which is then expected to
-        // return a `Box<dyn Any + Send + 'static>`.
-        // In Miri, `miri_start_unwind` is passed exactly that type, so we make the `payload` simply
-        // a pointer to `Box<dyn Any + Send + 'static>`.
-
-        // Get all the arguments.
-        let [try_fn, data, catch_fn] = check_intrinsic_arg_count(args)?;
-        let try_fn = this.read_pointer(try_fn)?;
-        let data = this.read_immediate(data)?;
-        let catch_fn = this.read_pointer(catch_fn)?;
-
-        // Now we make a function call, and pass `data` as first and only argument.
-        let f_instance = this.get_ptr_fn(try_fn)?.as_instance()?;
-        trace!("try_fn: {:?}", f_instance);
-        #[allow(clippy::cloned_ref_to_slice_refs)] // the code is clearer as-is
-        this.call_function(
-            f_instance,
-            ExternAbi::Rust,
-            &[data.clone()],
-            None,
-            // Directly return to caller.
-            ReturnContinuation::Goto { ret, unwind: mir::UnwindAction::Continue },
-        )?;
-
-        // We ourselves will return `0`, eventually (will be overwritten if we catch a panic).
-        this.write_null(dest)?;
-
-        // In unwind mode, we tag this frame with the extra data needed to catch unwinding.
-        // This lets `handle_stack_pop` (below) know that we should stop unwinding
-        // when we pop this frame.
-        if this.tcx.sess.panic_strategy() == PanicStrategy::Unwind {
-            this.frame_mut().extra.catch_unwind =
-                Some(CatchUnwindData { catch_fn, data, dest: dest.clone(), ret });
-        }
-
-        interp_ok(())
-    }
-
-    fn handle_stack_pop_unwind(
-        &mut self,
-        mut extra: FrameExtra<'tcx>,
-        unwinding: bool,
-    ) -> InterpResult<'tcx, ReturnAction> {
-        let this = self.eval_context_mut();
-        trace!("handle_stack_pop_unwind(extra = {:?}, unwinding = {})", extra, unwinding);
-
-        // We only care about `catch_panic` if we're unwinding - if we're doing a normal
-        // return, then we don't need to do anything special.
-        if let (true, Some(catch_unwind)) = (unwinding, extra.catch_unwind.take()) {
-            // We've just popped a frame that was pushed by `catch_unwind`,
-            // and we are unwinding, so we should catch that.
-            trace!(
-                "unwinding: found catch_panic frame during unwinding: {:?}",
-                this.frame().instance()
-            );
-
-            // We set the return value of `catch_unwind` to 1, since there was a panic.
-            this.write_scalar(Scalar::from_i32(1), &catch_unwind.dest)?;
-
-            // The Thread's `panic_payload` holds what was passed to `miri_start_unwind`.
-            // This is exactly the second argument we need to pass to `catch_fn`.
-            let payload = this.active_thread_mut().panic_payloads.pop().unwrap();
-
-            // Push the `catch_fn` stackframe.
-            let f_instance = this.get_ptr_fn(catch_unwind.catch_fn)?.as_instance()?;
-            trace!("catch_fn: {:?}", f_instance);
-            this.call_function(
-                f_instance,
-                ExternAbi::Rust,
-                &[catch_unwind.data, payload],
-                None,
-                // Directly return to caller of `catch_unwind`.
-                ReturnContinuation::Goto {
-                    ret: catch_unwind.ret,
-                    // `catch_fn` must not unwind.
-                    unwind: mir::UnwindAction::Unreachable,
-                },
-            )?;
-
-            // We pushed a new stack frame, the engine should not do any jumping now!
-            interp_ok(ReturnAction::NoJump)
-        } else {
-            interp_ok(ReturnAction::Normal)
-        }
-    }
-
     /// Start a panic in the interpreter with the given message as payload.
     fn start_panic(&mut self, msg: &str, unwind: mir::UnwindAction) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
diff --git a/src/tools/miri/src/shims/tls.rs b/src/tools/miri/src/shims/tls.rs
index 7182637437a..1200029692d 100644
--- a/src/tools/miri/src/shims/tls.rs
+++ b/src/tools/miri/src/shims/tls.rs
@@ -302,7 +302,7 @@ trait EvalContextPrivExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
         // Windows has a special magic linker section that is run on certain events.
         // We don't support most of that, but just enough to make thread-local dtors in `std` work.
-        interp_ok(this.lookup_link_section(".CRT$XLB")?)
+        interp_ok(this.lookup_link_section(|section| section == ".CRT$XLB")?)
     }
 
     fn schedule_windows_tls_dtor(&mut self, dtor: ImmTy<'tcx>) -> InterpResult<'tcx> {
diff --git a/src/tools/miri/src/shims/unix/fs.rs b/src/tools/miri/src/shims/unix/fs.rs
index 0f7d453b296..0f2878ad26c 100644
--- a/src/tools/miri/src/shims/unix/fs.rs
+++ b/src/tools/miri/src/shims/unix/fs.rs
@@ -132,12 +132,12 @@ trait EvalContextExtPrivate<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let buf = this.deref_pointer_as(buf_op, this.libc_ty_layout("stat"))?;
         this.write_int_fields_named(
             &[
-                ("st_dev", 0),
+                ("st_dev", metadata.dev.into()),
                 ("st_mode", mode.try_into().unwrap()),
                 ("st_nlink", 0),
                 ("st_ino", 0),
-                ("st_uid", 0),
-                ("st_gid", 0),
+                ("st_uid", metadata.uid.into()),
+                ("st_gid", metadata.gid.into()),
                 ("st_rdev", 0),
                 ("st_atime", access_sec.into()),
                 ("st_mtime", modified_sec.into()),
@@ -1544,6 +1544,9 @@ struct FileMetadata {
     created: Option<(u64, u32)>,
     accessed: Option<(u64, u32)>,
     modified: Option<(u64, u32)>,
+    dev: u64,
+    uid: u32,
+    gid: u32,
 }
 
 impl FileMetadata {
@@ -1601,6 +1604,21 @@ impl FileMetadata {
         let modified = extract_sec_and_nsec(metadata.modified())?;
 
         // FIXME: Provide more fields using platform specific methods.
-        interp_ok(Ok(FileMetadata { mode, size, created, accessed, modified }))
+
+        cfg_select! {
+            unix => {
+                use std::os::unix::fs::MetadataExt;
+                let dev = metadata.dev();
+                let uid = metadata.uid();
+                let gid = metadata.gid();
+            }
+            _ => {
+                let dev = 0;
+                let uid = 0;
+                let gid = 0;
+            }
+        }
+
+        interp_ok(Ok(FileMetadata { mode, size, created, accessed, modified, dev, uid, gid }))
     }
 }
diff --git a/src/tools/miri/src/shims/unwind.rs b/src/tools/miri/src/shims/unwind.rs
new file mode 100644
index 00000000000..ba0c50b54b4
--- /dev/null
+++ b/src/tools/miri/src/shims/unwind.rs
@@ -0,0 +1,160 @@
+//! Unwinding runtime for Miri.
+//!
+//! The core pieces of the runtime are:
+//! - An implementation of `catch_unwind` that pushes the invoked stack frame with
+//!   some extra metadata derived from the panic-catching arguments of `catch_unwind`.
+//! - A hack in `libpanic_unwind` that calls the `miri_start_unwind` intrinsic instead of the
+//!   target-native panic runtime. (This lives in the rustc repo.)
+//! - An implementation of `miri_start_unwind` that stores its argument (the panic payload), and
+//!   then immediately returns, but on the *unwind* edge (not the normal return edge), thus
+//!   initiating unwinding.
+//! - A hook executed each time a frame is popped, such that if the frame pushed by `catch_unwind`
+//!   gets popped *during unwinding*, we take the panic payload and store it according to the extra
+//!   metadata we remembered when pushing said frame.
+
+use rustc_abi::ExternAbi;
+use rustc_middle::mir;
+use rustc_target::spec::PanicStrategy;
+
+use self::helpers::check_intrinsic_arg_count;
+use crate::*;
+
+/// Holds all of the relevant data for when unwinding hits a `try` frame.
+#[derive(Debug)]
+pub struct CatchUnwindData<'tcx> {
+    /// The `catch_fn` callback to call in case of a panic.
+    catch_fn: Pointer,
+    /// The `data` argument for that callback.
+    data: ImmTy<'tcx>,
+    /// The return place from the original call to `try`.
+    dest: MPlaceTy<'tcx>,
+    /// The return block from the original call to `try`.
+    ret: Option<mir::BasicBlock>,
+}
+
+impl VisitProvenance for CatchUnwindData<'_> {
+    fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
+        let CatchUnwindData { catch_fn, data, dest, ret: _ } = self;
+        catch_fn.visit_provenance(visit);
+        data.visit_provenance(visit);
+        dest.visit_provenance(visit);
+    }
+}
+
+impl<'tcx> EvalContextExt<'tcx> for crate::MiriInterpCx<'tcx> {}
+pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
+    /// Handles the special `miri_start_unwind` intrinsic, which is called
+    /// by libpanic_unwind to delegate the actual unwinding process to Miri.
+    fn handle_miri_start_unwind(&mut self, payload: &OpTy<'tcx>) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+
+        trace!("miri_start_unwind: {:?}", this.frame().instance());
+
+        let payload = this.read_immediate(payload)?;
+        let thread = this.active_thread_mut();
+        thread.unwind_payloads.push(payload);
+
+        interp_ok(())
+    }
+
+    /// Handles the `catch_unwind` intrinsic.
+    fn handle_catch_unwind(
+        &mut self,
+        args: &[OpTy<'tcx>],
+        dest: &MPlaceTy<'tcx>,
+        ret: Option<mir::BasicBlock>,
+    ) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+
+        // Signature:
+        //   fn catch_unwind(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32
+        // Calls `try_fn` with `data` as argument. If that executes normally, returns 0.
+        // If that unwinds, calls `catch_fn` with the first argument being `data` and
+        // then second argument being a target-dependent `payload` (i.e. it is up to us to define
+        // what that is), and returns 1.
+        // The `payload` is passed (by libstd) to `__rust_panic_cleanup`, which is then expected to
+        // return a `Box<dyn Any + Send + 'static>`.
+        // In Miri, `miri_start_unwind` is passed exactly that type, so we make the `payload` simply
+        // a pointer to `Box<dyn Any + Send + 'static>`.
+
+        // Get all the arguments.
+        let [try_fn, data, catch_fn] = check_intrinsic_arg_count(args)?;
+        let try_fn = this.read_pointer(try_fn)?;
+        let data = this.read_immediate(data)?;
+        let catch_fn = this.read_pointer(catch_fn)?;
+
+        // Now we make a function call, and pass `data` as first and only argument.
+        let f_instance = this.get_ptr_fn(try_fn)?.as_instance()?;
+        trace!("try_fn: {:?}", f_instance);
+        #[allow(clippy::cloned_ref_to_slice_refs)] // the code is clearer as-is
+        this.call_function(
+            f_instance,
+            ExternAbi::Rust,
+            &[data.clone()],
+            None,
+            // Directly return to caller.
+            ReturnContinuation::Goto { ret, unwind: mir::UnwindAction::Continue },
+        )?;
+
+        // We ourselves will return `0`, eventually (will be overwritten if we catch a panic).
+        this.write_null(dest)?;
+
+        // In unwind mode, we tag this frame with the extra data needed to catch unwinding.
+        // This lets `handle_stack_pop` (below) know that we should stop unwinding
+        // when we pop this frame.
+        if this.tcx.sess.panic_strategy() == PanicStrategy::Unwind {
+            this.frame_mut().extra.catch_unwind =
+                Some(CatchUnwindData { catch_fn, data, dest: dest.clone(), ret });
+        }
+
+        interp_ok(())
+    }
+
+    fn handle_stack_pop_unwind(
+        &mut self,
+        mut extra: FrameExtra<'tcx>,
+        unwinding: bool,
+    ) -> InterpResult<'tcx, ReturnAction> {
+        let this = self.eval_context_mut();
+        trace!("handle_stack_pop_unwind(extra = {:?}, unwinding = {})", extra, unwinding);
+
+        // We only care about `catch_panic` if we're unwinding - if we're doing a normal
+        // return, then we don't need to do anything special.
+        if let (true, Some(catch_unwind)) = (unwinding, extra.catch_unwind.take()) {
+            // We've just popped a frame that was pushed by `catch_unwind`,
+            // and we are unwinding, so we should catch that.
+            trace!(
+                "unwinding: found catch_panic frame during unwinding: {:?}",
+                this.frame().instance()
+            );
+
+            // We set the return value of `catch_unwind` to 1, since there was a panic.
+            this.write_scalar(Scalar::from_i32(1), &catch_unwind.dest)?;
+
+            // The Thread's `panic_payload` holds what was passed to `miri_start_unwind`.
+            // This is exactly the second argument we need to pass to `catch_fn`.
+            let payload = this.active_thread_mut().unwind_payloads.pop().unwrap();
+
+            // Push the `catch_fn` stackframe.
+            let f_instance = this.get_ptr_fn(catch_unwind.catch_fn)?.as_instance()?;
+            trace!("catch_fn: {:?}", f_instance);
+            this.call_function(
+                f_instance,
+                ExternAbi::Rust,
+                &[catch_unwind.data, payload],
+                None,
+                // Directly return to caller of `catch_unwind`.
+                ReturnContinuation::Goto {
+                    ret: catch_unwind.ret,
+                    // `catch_fn` must not unwind.
+                    unwind: mir::UnwindAction::Unreachable,
+                },
+            )?;
+
+            // We pushed a new stack frame, the engine should not do any jumping now!
+            interp_ok(ReturnAction::NoJump)
+        } else {
+            interp_ok(ReturnAction::Normal)
+        }
+    }
+}
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.rs b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.rs
index 047fe07df14..5778765589d 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.rs
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.rs
@@ -1,4 +1,6 @@
 //@ignore-target: windows # No pthreads on Windows
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
 
 /// Test that destroying a pthread_cond twice fails, even without a check for number validity
 
@@ -15,6 +17,6 @@ fn main() {
         libc::pthread_cond_destroy(cond.as_mut_ptr());
 
         libc::pthread_cond_destroy(cond.as_mut_ptr());
-        //~^ ERROR: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+        //~^ ERROR: /Undefined Behavior: reading memory .*, but memory is uninitialized/
     }
 }
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.stderr b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.stderr
index 7abdfa87f75..6156070cf95 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.stderr
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.rs:LL:CC
    |
 LL |         libc::pthread_cond_destroy(cond.as_mut_ptr());
@@ -9,6 +9,9 @@ LL |         libc::pthread_cond_destroy(cond.as_mut_ptr());
    = note: BACKTRACE:
    = note: inside `main` at tests/fail-dep/concurrency/libc_pthread_cond_double_destroy.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.rs b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.rs
index 90e33d58673..91169660491 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.rs
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.rs
@@ -1,5 +1,7 @@
 //@ignore-target: windows # No pthreads on Windows
 //@ignore-target: apple # Our macOS condattr don't have any fields so we do not notice this.
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
 
 /// Test that destroying a pthread_condattr twice fails, even without a check for number validity
 
@@ -13,6 +15,6 @@ fn main() {
         libc::pthread_condattr_destroy(attr.as_mut_ptr());
 
         libc::pthread_condattr_destroy(attr.as_mut_ptr());
-        //~^ ERROR: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+        //~^ ERROR: /Undefined Behavior: reading memory .*, but memory is uninitialized/
     }
 }
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.stderr b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.stderr
index 28a66253ae8..da64970ff2e 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.stderr
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.rs:LL:CC
    |
 LL |         libc::pthread_condattr_destroy(attr.as_mut_ptr());
@@ -9,6 +9,9 @@ LL |         libc::pthread_condattr_destroy(attr.as_mut_ptr());
    = note: BACKTRACE:
    = note: inside `main` at tests/fail-dep/concurrency/libc_pthread_condattr_double_destroy.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.rs b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.rs
index 1792c227e13..f04fe8be6b3 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.rs
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.rs
@@ -1,4 +1,6 @@
 //@ignore-target: windows # No pthreads on Windows
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
 
 /// Test that destroying a pthread_mutex twice fails, even without a check for number validity
 
@@ -16,6 +18,6 @@ fn main() {
         libc::pthread_mutex_destroy(mutex.as_mut_ptr());
 
         libc::pthread_mutex_destroy(mutex.as_mut_ptr());
-        //~^ ERROR: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+        //~^ ERROR: /Undefined Behavior: reading memory .*, but memory is uninitialized/
     }
 }
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.stderr b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.stderr
index e7a6dee0203..05db823b252 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.stderr
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.rs:LL:CC
    |
 LL |         libc::pthread_mutex_destroy(mutex.as_mut_ptr());
@@ -9,6 +9,9 @@ LL |         libc::pthread_mutex_destroy(mutex.as_mut_ptr());
    = note: BACKTRACE:
    = note: inside `main` at tests/fail-dep/concurrency/libc_pthread_mutex_double_destroy.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.rs b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.rs
index 3711c1f8dc1..d9daf5259bb 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.rs
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.rs
@@ -1,4 +1,6 @@
 //@ignore-target: windows # No pthreads on Windows
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
 
 /// Test that destroying a pthread_mutexattr twice fails, even without a check for number validity
 
@@ -12,6 +14,6 @@ fn main() {
         libc::pthread_mutexattr_destroy(attr.as_mut_ptr());
 
         libc::pthread_mutexattr_destroy(attr.as_mut_ptr());
-        //~^ ERROR: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+        //~^ ERROR: /Undefined Behavior: reading memory .*, but memory is uninitialized/
     }
 }
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.stderr b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.stderr
index 0c9ee71de45..ee3883de36b 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.stderr
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.rs:LL:CC
    |
 LL |         libc::pthread_mutexattr_destroy(attr.as_mut_ptr());
@@ -9,6 +9,9 @@ LL |         libc::pthread_mutexattr_destroy(attr.as_mut_ptr());
    = note: BACKTRACE:
    = note: inside `main` at tests/fail-dep/concurrency/libc_pthread_mutexattr_double_destroy.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.rs b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.rs
index 6a31e972e68..720ba71d238 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.rs
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.rs
@@ -1,4 +1,6 @@
 //@ignore-target: windows # No pthreads on Windows
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
 
 /// Test that destroying a pthread_rwlock twice fails, even without a check for number validity
 
@@ -9,6 +11,6 @@ fn main() {
         libc::pthread_rwlock_destroy(&mut lock);
 
         libc::pthread_rwlock_destroy(&mut lock);
-        //~^ ERROR: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+        //~^ ERROR: /Undefined Behavior: reading memory .*, but memory is uninitialized/
     }
 }
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.stderr b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.stderr
index 836f0d060bd..430398dc8fd 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.stderr
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.rs:LL:CC
    |
 LL |         libc::pthread_rwlock_destroy(&mut lock);
@@ -9,6 +9,9 @@ LL |         libc::pthread_rwlock_destroy(&mut lock);
    = note: BACKTRACE:
    = note: inside `main` at tests/fail-dep/concurrency/libc_pthread_rwlock_double_destroy.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.rs b/src/tools/miri/tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.rs
new file mode 100644
index 00000000000..107a3db91d8
--- /dev/null
+++ b/src/tools/miri/tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.rs
@@ -0,0 +1,6 @@
+fn main() {
+    let v: Vec<u16> = vec![1, 2];
+    // This read is also misaligned. We make sure that the OOB message has priority.
+    let x = unsafe { *v.as_ptr().wrapping_byte_sub(5) }; //~ ERROR: before the beginning of the allocation
+    panic!("this should never print: {}", x);
+}
diff --git a/src/tools/miri/tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.stderr b/src/tools/miri/tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.stderr
new file mode 100644
index 00000000000..5c37caa1ebf
--- /dev/null
+++ b/src/tools/miri/tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.stderr
@@ -0,0 +1,21 @@
+error: Undefined Behavior: memory access failed: attempting to access 2 bytes, but got ALLOC-0x5 which points to before the beginning of the allocation
+  --> tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.rs:LL:CC
+   |
+LL |     let x = unsafe { *v.as_ptr().wrapping_byte_sub(5) };
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+help: ALLOC was allocated here:
+  --> tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.rs:LL:CC
+   |
+LL |     let v: Vec<u16> = vec![1, 2];
+   |                       ^^^^^^^^^^
+   = note: BACKTRACE (of the first span):
+   = note: inside `main` at tests/fail/dangling_pointers/out_of_bounds_read_neg_offset.rs:LL:CC
+   = note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+
diff --git a/src/tools/miri/tests/fail/function_calls/arg_inplace_observe_after.stderr b/src/tools/miri/tests/fail/function_calls/arg_inplace_observe_after.stderr
index 6a7d9a495f9..3252368ea6d 100644
--- a/src/tools/miri/tests/fail/function_calls/arg_inplace_observe_after.stderr
+++ b/src/tools/miri/tests/fail/function_calls/arg_inplace_observe_after.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0x0..0x4], but memory is uninitialized at [0x0..0x4], and this operation requires initialized memory
   --> tests/fail/function_calls/arg_inplace_observe_after.rs:LL:CC
    |
 LL |             _observe = non_copy.0;
@@ -9,6 +9,11 @@ LL |             _observe = non_copy.0;
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/function_calls/arg_inplace_observe_after.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0x0..0x4], in this allocation:
+ALLOC (stack variable, size: 4, align: 4) {
+    __ __ __ __                                     │ ░░░░
+}
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/function_calls/arg_inplace_observe_during.none.stderr b/src/tools/miri/tests/fail/function_calls/arg_inplace_observe_during.none.stderr
index 0fc634bb7fc..09a5b9a6496 100644
--- a/src/tools/miri/tests/fail/function_calls/arg_inplace_observe_during.none.stderr
+++ b/src/tools/miri/tests/fail/function_calls/arg_inplace_observe_during.none.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0x0..0x4], but memory is uninitialized at [0x0..0x4], and this operation requires initialized memory
   --> tests/fail/function_calls/arg_inplace_observe_during.rs:LL:CC
    |
 LL |     unsafe { ptr.read() };
@@ -14,6 +14,11 @@ note: inside `main`
 LL |             Call(_unit = change_arg(Move(*ptr), ptr), ReturnTo(after_call), UnwindContinue())
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+Uninitialized memory occurred at ALLOC[0x0..0x4], in this allocation:
+ALLOC (stack variable, size: 4, align: 4) {
+    __ __ __ __                                     │ ░░░░
+}
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/function_calls/return_pointer_aliasing_read.none.stderr b/src/tools/miri/tests/fail/function_calls/return_pointer_aliasing_read.none.stderr
index 746ab2e59ca..24091547258 100644
--- a/src/tools/miri/tests/fail/function_calls/return_pointer_aliasing_read.none.stderr
+++ b/src/tools/miri/tests/fail/function_calls/return_pointer_aliasing_read.none.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0x0..0x4], but memory is uninitialized at [0x0..0x4], and this operation requires initialized memory
   --> tests/fail/function_calls/return_pointer_aliasing_read.rs:LL:CC
    |
 LL |     unsafe { ptr.read() };
@@ -14,6 +14,11 @@ note: inside `main`
 LL |             Call(*ptr = myfun(ptr), ReturnTo(after_call), UnwindContinue())
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+Uninitialized memory occurred at ALLOC[0x0..0x4], in this allocation:
+ALLOC (stack variable, size: 4, align: 4) {
+    __ __ __ __                                     │ ░░░░
+}
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr b/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr
index 7747a75d1cf..93720ca7d27 100644
--- a/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr
+++ b/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr
@@ -3,7 +3,7 @@ thread 'main' panicked at tests/fail/function_calls/return_pointer_on_unwind.rs:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 note: in Miri, you may have to set `MIRIFLAGS=-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0x0..0x4], but memory is uninitialized at [0x0..0x4], and this operation requires initialized memory
   --> tests/fail/function_calls/return_pointer_on_unwind.rs:LL:CC
    |
 LL |     dbg!(x.0);
@@ -15,6 +15,19 @@ LL |     dbg!(x.0);
    = note: inside `main` at RUSTLIB/std/src/macros.rs:LL:CC
    = note: this error originates in the macro `dbg` (in Nightly builds, run with -Z macro-backtrace for more info)
 
+Uninitialized memory occurred at ALLOC[0x0..0x4], in this allocation:
+ALLOC (stack variable, size: 132, align: 4) {
+    0x00 │ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+    0x10 │ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+    0x20 │ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+    0x30 │ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+    0x40 │ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+    0x50 │ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+    0x60 │ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+    0x70 │ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ │ ░░░░░░░░░░░░░░░░
+    0x80 │ __ __ __ __                                     │ ░░░░
+}
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_data.rs b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_data.rs
index 0c305eed6e1..c03e468cfba 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_data.rs
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_data.rs
@@ -1,4 +1,7 @@
 //@compile-flags: -Zmiri-disable-validation
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
+
 #![feature(core_intrinsics, custom_mir)]
 use std::intrinsics::mir::*;
 
@@ -9,7 +12,7 @@ use std::intrinsics::mir::*;
 pub unsafe fn deref_meta(p: *const *const [i32]) -> usize {
     mir! {
         {
-            RET = PtrMetadata(*p); //~ ERROR: Undefined Behavior: using uninitialized data
+            RET = PtrMetadata(*p); //~ ERROR: /Undefined Behavior: .* but memory is uninitialized/
             Return()
         }
     }
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_data.stderr b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_data.stderr
index 1c22876ba43..1e7f500edb2 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_data.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_data.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail/intrinsics/ptr_metadata_uninit_slice_data.rs:LL:CC
    |
 LL |             RET = PtrMetadata(*p);
@@ -14,6 +14,9 @@ note: inside `main`
 LL |         let _meta = deref_meta(p.as_ptr().cast());
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.rs b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.rs
index a2ffdc92c4e..7053c0f6e18 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.rs
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.rs
@@ -1,4 +1,7 @@
 //@compile-flags: -Zmiri-disable-validation
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]+..0x[0-9a-z]+\]" -> "[0xX..0xY]"
+
 #![feature(core_intrinsics, custom_mir)]
 use std::intrinsics::mir::*;
 
@@ -9,7 +12,7 @@ use std::intrinsics::mir::*;
 pub unsafe fn deref_meta(p: *const *const [i32]) -> usize {
     mir! {
         {
-            RET = PtrMetadata(*p); //~ ERROR: Undefined Behavior: using uninitialized data
+            RET = PtrMetadata(*p); //~ ERROR: /Undefined Behavior: .* but memory is uninitialized/
             Return()
         }
     }
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr
index 00e63b1275f..80b4c8bec0d 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr
@@ -12,7 +12,7 @@ LL |         (*p.as_mut_ptr().cast::<[*const i32; 2]>())[0] = 4 as *const i32;
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/intrinsics/ptr_metadata_uninit_slice_len.rs:LL:CC
 
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail/intrinsics/ptr_metadata_uninit_slice_len.rs:LL:CC
    |
 LL |             RET = PtrMetadata(*p);
@@ -28,6 +28,9 @@ note: inside `main`
 LL |         let _meta = deref_meta(p.as_ptr().cast());
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error; 1 warning emitted
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_thin.rs b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_thin.rs
index e5a51289a8a..3ba29847337 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_thin.rs
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_thin.rs
@@ -1,4 +1,7 @@
 //@compile-flags: -Zmiri-disable-validation
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
+
 #![feature(core_intrinsics, custom_mir)]
 use std::intrinsics::mir::*;
 
@@ -9,7 +12,7 @@ use std::intrinsics::mir::*;
 pub unsafe fn deref_meta(p: *const *const i32) -> () {
     mir! {
         {
-            RET = PtrMetadata(*p); //~ ERROR: Undefined Behavior: using uninitialized data
+            RET = PtrMetadata(*p); //~ ERROR: /Undefined Behavior: .*, but memory is uninitialized/
             Return()
         }
     }
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_thin.stderr b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_thin.stderr
index 24066953d79..7a1f3d6ea84 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_thin.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_thin.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail/intrinsics/ptr_metadata_uninit_thin.rs:LL:CC
    |
 LL |             RET = PtrMetadata(*p);
@@ -14,6 +14,9 @@ note: inside `main`
 LL |         let _meta = deref_meta(p.as_ptr());
    |                     ^^^^^^^^^^^^^^^^^^^^^^
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.rs b/src/tools/miri/tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.rs
new file mode 100644
index 00000000000..0085e2af367
--- /dev/null
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.rs
@@ -0,0 +1,6 @@
+fn main() {
+    let v = [0i8; 4];
+    let x = &v as *const i8;
+    let x = unsafe { x.wrapping_offset(-1).offset(-1) }; //~ERROR: before the beginning of the allocation
+    panic!("this should never print: {:?}", x);
+}
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.stderr b/src/tools/miri/tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.stderr
new file mode 100644
index 00000000000..495aaf8d40e
--- /dev/null
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.stderr
@@ -0,0 +1,20 @@
+error: Undefined Behavior: in-bounds pointer arithmetic failed: attempting to offset pointer by -1 bytes, but got ALLOC-0x1 which points to before the beginning of the allocation
+  --> tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.rs:LL:CC
+   |
+LL |     let x = unsafe { x.wrapping_offset(-1).offset(-1) };
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+help: ALLOC was allocated here:
+  --> tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.rs:LL:CC
+   |
+LL |     let v = [0i8; 4];
+   |         ^
+   = note: BACKTRACE (of the first span):
+   = note: inside `main` at tests/fail/intrinsics/ptr_offset_out_of_bounds_neg2.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+
diff --git a/src/tools/miri/tests/fail/read_from_trivial_switch.rs b/src/tools/miri/tests/fail/read_from_trivial_switch.rs
index d34b1cd5820..2696c42aeae 100644
--- a/src/tools/miri/tests/fail/read_from_trivial_switch.rs
+++ b/src/tools/miri/tests/fail/read_from_trivial_switch.rs
@@ -4,11 +4,14 @@
 //
 // See <https://github.com/rust-lang/miri/issues/4237>.
 
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
+
 use std::mem::MaybeUninit;
 
 fn main() {
     let uninit: MaybeUninit<i32> = MaybeUninit::uninit();
     let bad_ref: &i32 = unsafe { uninit.assume_init_ref() };
     let &(0 | _) = bad_ref;
-    //~^ ERROR: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+    //~^ ERROR: /Undefined Behavior: .*, but memory is uninitialized .* requires initialized memory/
 }
diff --git a/src/tools/miri/tests/fail/read_from_trivial_switch.stderr b/src/tools/miri/tests/fail/read_from_trivial_switch.stderr
index 923d836ee0c..1dcc341b7e6 100644
--- a/src/tools/miri/tests/fail/read_from_trivial_switch.stderr
+++ b/src/tools/miri/tests/fail/read_from_trivial_switch.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail/read_from_trivial_switch.rs:LL:CC
    |
 LL |     let &(0 | _) = bad_ref;
@@ -9,6 +9,9 @@ LL |     let &(0 | _) = bad_ref;
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/read_from_trivial_switch.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/uninit/padding-enum.rs b/src/tools/miri/tests/fail/uninit/padding-enum.rs
index e1a16bea23c..606fa21016f 100644
--- a/src/tools/miri/tests/fail/uninit/padding-enum.rs
+++ b/src/tools/miri/tests/fail/uninit/padding-enum.rs
@@ -1,3 +1,6 @@
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
+
 use std::mem;
 
 // We have three fields to avoid the ScalarPair optimization.
diff --git a/src/tools/miri/tests/fail/uninit/padding-enum.stderr b/src/tools/miri/tests/fail/uninit/padding-enum.stderr
index a9a5568f4e8..64229ac8817 100644
--- a/src/tools/miri/tests/fail/uninit/padding-enum.stderr
+++ b/src/tools/miri/tests/fail/uninit/padding-enum.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail/uninit/padding-enum.rs:LL:CC
    |
 LL |         let _val = *c.add(padding_offset);
@@ -9,6 +9,9 @@ LL |         let _val = *c.add(padding_offset);
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/uninit/padding-enum.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/uninit/padding-pair.rs b/src/tools/miri/tests/fail/uninit/padding-pair.rs
index c8c00b3c65a..70ae48ff77d 100644
--- a/src/tools/miri/tests/fail/uninit/padding-pair.rs
+++ b/src/tools/miri/tests/fail/uninit/padding-pair.rs
@@ -1,3 +1,6 @@
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
+
 #![feature(core_intrinsics)]
 
 use std::mem::{self, MaybeUninit};
diff --git a/src/tools/miri/tests/fail/uninit/padding-pair.stderr b/src/tools/miri/tests/fail/uninit/padding-pair.stderr
index d281a351d41..2e7a577f204 100644
--- a/src/tools/miri/tests/fail/uninit/padding-pair.stderr
+++ b/src/tools/miri/tests/fail/uninit/padding-pair.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail/uninit/padding-pair.rs:LL:CC
    |
 LL |     let v = unsafe { *z.offset(first_undef) };
@@ -9,6 +9,9 @@ LL |     let v = unsafe { *z.offset(first_undef) };
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/uninit/padding-pair.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/uninit/padding-struct.stderr b/src/tools/miri/tests/fail/uninit/padding-struct.stderr
index 3298f6a4510..05d754625d3 100644
--- a/src/tools/miri/tests/fail/uninit/padding-struct.stderr
+++ b/src/tools/miri/tests/fail/uninit/padding-struct.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0x1..0x2], but memory is uninitialized at [0x1..0x2], and this operation requires initialized memory
   --> tests/fail/uninit/padding-struct.rs:LL:CC
    |
 LL |         let _val = *c.add(1);
@@ -9,6 +9,11 @@ LL |         let _val = *c.add(1);
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/uninit/padding-struct.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0x1..0x2], in this allocation:
+ALLOC (stack variable, size: 4, align: 2) {
+    00 __ 00 00                                     │ .░..
+}
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/uninit/padding-wide-ptr.rs b/src/tools/miri/tests/fail/uninit/padding-wide-ptr.rs
index 4e363dbf81e..549785e0223 100644
--- a/src/tools/miri/tests/fail/uninit/padding-wide-ptr.rs
+++ b/src/tools/miri/tests/fail/uninit/padding-wide-ptr.rs
@@ -1,3 +1,6 @@
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
+
 use std::mem;
 
 // If this is `None`, the metadata becomes padding.
diff --git a/src/tools/miri/tests/fail/uninit/padding-wide-ptr.stderr b/src/tools/miri/tests/fail/uninit/padding-wide-ptr.stderr
index d92d05ae631..ce11320ca1b 100644
--- a/src/tools/miri/tests/fail/uninit/padding-wide-ptr.stderr
+++ b/src/tools/miri/tests/fail/uninit/padding-wide-ptr.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail/uninit/padding-wide-ptr.rs:LL:CC
    |
 LL |         let _val = *c.add(mem::size_of::<*const u8>());
@@ -9,6 +9,9 @@ LL |         let _val = *c.add(mem::size_of::<*const u8>());
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/uninit/padding-wide-ptr.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/uninit/transmute-pair-uninit.rs b/src/tools/miri/tests/fail/uninit/transmute-pair-uninit.rs
index 0ba5520a544..c1d284c7057 100644
--- a/src/tools/miri/tests/fail/uninit/transmute-pair-uninit.rs
+++ b/src/tools/miri/tests/fail/uninit/transmute-pair-uninit.rs
@@ -1,3 +1,6 @@
+//@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}"
+//@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]"
+
 #![feature(core_intrinsics)]
 
 use std::mem::{self, MaybeUninit};
diff --git a/src/tools/miri/tests/fail/uninit/transmute-pair-uninit.stderr b/src/tools/miri/tests/fail/uninit/transmute-pair-uninit.stderr
index 0ae0ce5de9c..eb049dd41ec 100644
--- a/src/tools/miri/tests/fail/uninit/transmute-pair-uninit.stderr
+++ b/src/tools/miri/tests/fail/uninit/transmute-pair-uninit.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0xX..0xY], but memory is uninitialized at [0xX..0xY], and this operation requires initialized memory
   --> tests/fail/uninit/transmute-pair-uninit.rs:LL:CC
    |
 LL |     let v = unsafe { *z.offset(first_undef) };
@@ -9,6 +9,9 @@ LL |     let v = unsafe { *z.offset(first_undef) };
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/uninit/transmute-pair-uninit.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0xX..0xY], in this allocation:
+ALLOC DUMP
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/uninit/uninit_byte_read.stderr b/src/tools/miri/tests/fail/uninit/uninit_byte_read.stderr
index d2a5a2d3831..5a5aa12987c 100644
--- a/src/tools/miri/tests/fail/uninit/uninit_byte_read.stderr
+++ b/src/tools/miri/tests/fail/uninit/uninit_byte_read.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0x5..0x6], but memory is uninitialized at [0x5..0x6], and this operation requires initialized memory
   --> tests/fail/uninit/uninit_byte_read.rs:LL:CC
    |
 LL |     let undef = unsafe { *v.as_ptr().add(5) };
@@ -9,6 +9,11 @@ LL |     let undef = unsafe { *v.as_ptr().add(5) };
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/uninit/uninit_byte_read.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0x5..0x6], in this allocation:
+ALLOC (Rust heap, size: 10, align: 1) {
+    __ __ __ __ __ __ __ __ __ __                   │ ░░░░░░░░░░
+}
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/fail/validity/invalid_int_op.stderr b/src/tools/miri/tests/fail/validity/invalid_int_op.stderr
index 6e24cadfc20..0b1915621b2 100644
--- a/src/tools/miri/tests/fail/validity/invalid_int_op.stderr
+++ b/src/tools/miri/tests/fail/validity/invalid_int_op.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
+error: Undefined Behavior: reading memory at ALLOC[0x0..0x4], but memory is uninitialized at [0x0..0x4], and this operation requires initialized memory
   --> tests/fail/validity/invalid_int_op.rs:LL:CC
    |
 LL |     let i = unsafe { std::mem::MaybeUninit::<i32>::uninit().assume_init() };
@@ -9,6 +9,11 @@ LL |     let i = unsafe { std::mem::MaybeUninit::<i32>::uninit().assume_init() }
    = note: BACKTRACE:
    = note: inside `main` at tests/fail/validity/invalid_int_op.rs:LL:CC
 
+Uninitialized memory occurred at ALLOC[0x0..0x4], in this allocation:
+ALLOC (stack variable, size: 4, align: 4) {
+    __ __ __ __                                     │ ░░░░
+}
+
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
 error: aborting due to 1 previous error
diff --git a/src/tools/miri/tests/native-lib/fail/tracing/partial_init.rs b/src/tools/miri/tests/native-lib/fail/tracing/partial_init.rs
new file mode 100644
index 00000000000..7ab160773ff
--- /dev/null
+++ b/src/tools/miri/tests/native-lib/fail/tracing/partial_init.rs
@@ -0,0 +1,25 @@
+//@only-target: x86_64-unknown-linux-gnu i686-unknown-linux-gnu
+//@compile-flags: -Zmiri-native-lib-enable-tracing
+
+extern "C" {
+    fn init_n(n: i32, ptr: *mut u8);
+}
+
+fn main() {
+    partial_init();
+}
+
+// Initialise the first 2 elements of the slice from native code, and check
+// that the 3rd is correctly deemed uninit.
+fn partial_init() {
+    let mut slice = std::mem::MaybeUninit::<[u8; 3]>::uninit();
+    let slice_ptr = slice.as_mut_ptr().cast::<u8>();
+    unsafe {
+        // Initialize the first two elements.
+        init_n(2, slice_ptr);
+        assert!(*slice_ptr == 0);
+        assert!(*slice_ptr.offset(1) == 0);
+        // Reading the third is UB!
+        let _val = *slice_ptr.offset(2); //~ ERROR: /Undefined Behavior: reading memory.*, but memory is uninitialized/
+    }
+}
diff --git a/src/tools/miri/tests/native-lib/fail/tracing/partial_init.stderr b/src/tools/miri/tests/native-lib/fail/tracing/partial_init.stderr
new file mode 100644
index 00000000000..74a599ede5c
--- /dev/null
+++ b/src/tools/miri/tests/native-lib/fail/tracing/partial_init.stderr
@@ -0,0 +1,44 @@
+warning: sharing memory with a native function called via FFI
+  --> tests/native-lib/fail/tracing/partial_init.rs:LL:CC
+   |
+LL |         init_n(2, slice_ptr);
+   |         ^^^^^^^^^^^^^^^^^^^^ sharing memory with a native function
+   |
+   = help: when memory is shared with a native function call, Miri can only track initialisation and provenance on a best-effort basis
+   = help: in particular, Miri assumes that the native call initializes all memory it has written to
+   = help: Miri also assumes that any part of this memory may be a pointer that is permitted to point to arbitrary exposed memory
+   = help: what this means is that Miri will easily miss Undefined Behavior related to incorrect usage of this shared memory, so you should not take a clean Miri run as a signal that your FFI code is UB-free
+   = help: tracing memory accesses in native code is not yet fully implemented, so there can be further imprecisions beyond what is documented here
+   = note: BACKTRACE:
+   = note: inside `partial_init` at tests/native-lib/fail/tracing/partial_init.rs:LL:CC
+note: inside `main`
+  --> tests/native-lib/fail/tracing/partial_init.rs:LL:CC
+   |
+LL |     partial_init();
+   |     ^^^^^^^^^^^^^^
+
+error: Undefined Behavior: reading memory at ALLOC[0x2..0x3], but memory is uninitialized at [0x2..0x3], and this operation requires initialized memory
+  --> tests/native-lib/fail/tracing/partial_init.rs:LL:CC
+   |
+LL |         let _val = *slice_ptr.offset(2);
+   |                    ^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `partial_init` at tests/native-lib/fail/tracing/partial_init.rs:LL:CC
+note: inside `main`
+  --> tests/native-lib/fail/tracing/partial_init.rs:LL:CC
+   |
+LL |     partial_init();
+   |     ^^^^^^^^^^^^^^
+
+Uninitialized memory occurred at ALLOC[0x2..0x3], in this allocation:
+ALLOC (stack variable, size: 3, align: 1) {
+    ╾00[wildcard] (1 ptr byte)╼ ╾00[wildcard] (1 ptr byte)╼ __                                        │ ━━░
+}
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error; 1 warning emitted
+
diff --git a/src/tools/miri/tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs b/src/tools/miri/tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs
new file mode 100644
index 00000000000..b78c29d98db
--- /dev/null
+++ b/src/tools/miri/tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs
@@ -0,0 +1,29 @@
+//@only-target: x86_64-unknown-linux-gnu i686-unknown-linux-gnu
+//@compile-flags: -Zmiri-permissive-provenance -Zmiri-native-lib-enable-tracing
+
+extern "C" {
+    fn do_one_deref(ptr: *const *const *const i32) -> usize;
+}
+
+fn main() {
+    unexposed_reachable_alloc();
+}
+
+// Expose 2 pointers by virtue of doing a native read and assert that the 3rd in
+// the chain remains properly unexposed.
+fn unexposed_reachable_alloc() {
+    let inner = 42;
+    let intermediate_a = &raw const inner;
+    let intermediate_b = &raw const intermediate_a;
+    let exposed = &raw const intermediate_b;
+    // Discard the return value; it's just there so the access in C doesn't get optimised away.
+    unsafe { do_one_deref(exposed) };
+    // Native read should have exposed the address of intermediate_b...
+    let valid: *const i32 = std::ptr::with_exposed_provenance(intermediate_b.addr());
+    // but not of intermediate_a.
+    let invalid: *const i32 = std::ptr::with_exposed_provenance(intermediate_a.addr());
+    unsafe {
+        let _ok = *valid;
+        let _not_ok = *invalid; //~ ERROR: Undefined Behavior: memory access failed: attempting to access
+    }
+}
diff --git a/src/tools/miri/tests/native-lib/fail/tracing/unexposed_reachable_alloc.stderr b/src/tools/miri/tests/native-lib/fail/tracing/unexposed_reachable_alloc.stderr
new file mode 100644
index 00000000000..2d34dac1b3f
--- /dev/null
+++ b/src/tools/miri/tests/native-lib/fail/tracing/unexposed_reachable_alloc.stderr
@@ -0,0 +1,39 @@
+warning: sharing memory with a native function called via FFI
+  --> tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs:LL:CC
+   |
+LL |     unsafe { do_one_deref(exposed) };
+   |              ^^^^^^^^^^^^^^^^^^^^^ sharing memory with a native function
+   |
+   = help: when memory is shared with a native function call, Miri can only track initialisation and provenance on a best-effort basis
+   = help: in particular, Miri assumes that the native call initializes all memory it has written to
+   = help: Miri also assumes that any part of this memory may be a pointer that is permitted to point to arbitrary exposed memory
+   = help: what this means is that Miri will easily miss Undefined Behavior related to incorrect usage of this shared memory, so you should not take a clean Miri run as a signal that your FFI code is UB-free
+   = help: tracing memory accesses in native code is not yet fully implemented, so there can be further imprecisions beyond what is documented here
+   = note: BACKTRACE:
+   = note: inside `unexposed_reachable_alloc` at tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs:LL:CC
+note: inside `main`
+  --> tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs:LL:CC
+   |
+LL |     unexposed_reachable_alloc();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: Undefined Behavior: memory access failed: attempting to access 4 bytes, but got $HEX[noalloc] which is a dangling pointer (it has no provenance)
+  --> tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs:LL:CC
+   |
+LL |         let _not_ok = *invalid;
+   |                       ^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `unexposed_reachable_alloc` at tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs:LL:CC
+note: inside `main`
+  --> tests/native-lib/fail/tracing/unexposed_reachable_alloc.rs:LL:CC
+   |
+LL |     unexposed_reachable_alloc();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error; 1 warning emitted
+
diff --git a/src/tools/miri/tests/native-lib/pass/ptr_read_access.stderr b/src/tools/miri/tests/native-lib/pass/ptr_read_access.notrace.stderr
index 04a3025baef..04a3025baef 100644
--- a/src/tools/miri/tests/native-lib/pass/ptr_read_access.stderr
+++ b/src/tools/miri/tests/native-lib/pass/ptr_read_access.notrace.stderr
diff --git a/src/tools/miri/tests/native-lib/pass/ptr_read_access.stdout b/src/tools/miri/tests/native-lib/pass/ptr_read_access.notrace.stdout
index 1a8799abfc9..1a8799abfc9 100644
--- a/src/tools/miri/tests/native-lib/pass/ptr_read_access.stdout
+++ b/src/tools/miri/tests/native-lib/pass/ptr_read_access.notrace.stdout
diff --git a/src/tools/miri/tests/native-lib/pass/ptr_read_access.rs b/src/tools/miri/tests/native-lib/pass/ptr_read_access.rs
index 4c852135367..4f3c37f00c1 100644
--- a/src/tools/miri/tests/native-lib/pass/ptr_read_access.rs
+++ b/src/tools/miri/tests/native-lib/pass/ptr_read_access.rs
@@ -1,3 +1,7 @@
+//@revisions: trace notrace
+//@[trace] only-target: x86_64-unknown-linux-gnu i686-unknown-linux-gnu
+//@[trace] compile-flags: -Zmiri-native-lib-enable-tracing
+
 fn main() {
     test_access_pointer();
     test_access_simple();
diff --git a/src/tools/miri/tests/native-lib/pass/ptr_read_access.trace.stderr b/src/tools/miri/tests/native-lib/pass/ptr_read_access.trace.stderr
new file mode 100644
index 00000000000..c2a4508b7fc
--- /dev/null
+++ b/src/tools/miri/tests/native-lib/pass/ptr_read_access.trace.stderr
@@ -0,0 +1,19 @@
+warning: sharing memory with a native function called via FFI
+  --> tests/native-lib/pass/ptr_read_access.rs:LL:CC
+   |
+LL |     unsafe { print_pointer(&x) };
+   |              ^^^^^^^^^^^^^^^^^ sharing memory with a native function
+   |
+   = help: when memory is shared with a native function call, Miri can only track initialisation and provenance on a best-effort basis
+   = help: in particular, Miri assumes that the native call initializes all memory it has written to
+   = help: Miri also assumes that any part of this memory may be a pointer that is permitted to point to arbitrary exposed memory
+   = help: what this means is that Miri will easily miss Undefined Behavior related to incorrect usage of this shared memory, so you should not take a clean Miri run as a signal that your FFI code is UB-free
+   = help: tracing memory accesses in native code is not yet fully implemented, so there can be further imprecisions beyond what is documented here
+   = note: BACKTRACE:
+   = note: inside `test_access_pointer` at tests/native-lib/pass/ptr_read_access.rs:LL:CC
+note: inside `main`
+  --> tests/native-lib/pass/ptr_read_access.rs:LL:CC
+   |
+LL |     test_access_pointer();
+   |     ^^^^^^^^^^^^^^^^^^^^^
+
diff --git a/src/tools/miri/tests/native-lib/pass/ptr_read_access.trace.stdout b/src/tools/miri/tests/native-lib/pass/ptr_read_access.trace.stdout
new file mode 100644
index 00000000000..1a8799abfc9
--- /dev/null
+++ b/src/tools/miri/tests/native-lib/pass/ptr_read_access.trace.stdout
@@ -0,0 +1 @@
+printing pointer dereference from C: 42
diff --git a/src/tools/miri/tests/native-lib/pass/ptr_write_access.stderr b/src/tools/miri/tests/native-lib/pass/ptr_write_access.notrace.stderr
index c893b0d9f65..c893b0d9f65 100644
--- a/src/tools/miri/tests/native-lib/pass/ptr_write_access.stderr
+++ b/src/tools/miri/tests/native-lib/pass/ptr_write_access.notrace.stderr
diff --git a/src/tools/miri/tests/native-lib/pass/ptr_write_access.rs b/src/tools/miri/tests/native-lib/pass/ptr_write_access.rs
index 86a9c97f4ce..57def78b0ab 100644
--- a/src/tools/miri/tests/native-lib/pass/ptr_write_access.rs
+++ b/src/tools/miri/tests/native-lib/pass/ptr_write_access.rs
@@ -1,3 +1,6 @@
+//@revisions: trace notrace
+//@[trace] only-target: x86_64-unknown-linux-gnu i686-unknown-linux-gnu
+//@[trace] compile-flags: -Zmiri-native-lib-enable-tracing
 //@compile-flags: -Zmiri-permissive-provenance
 
 #![feature(box_as_ptr)]
diff --git a/src/tools/miri/tests/native-lib/pass/ptr_write_access.trace.stderr b/src/tools/miri/tests/native-lib/pass/ptr_write_access.trace.stderr
new file mode 100644
index 00000000000..dbf021b15be
--- /dev/null
+++ b/src/tools/miri/tests/native-lib/pass/ptr_write_access.trace.stderr
@@ -0,0 +1,19 @@
+warning: sharing memory with a native function called via FFI
+  --> tests/native-lib/pass/ptr_write_access.rs:LL:CC
+   |
+LL |     unsafe { increment_int(&mut x) };
+   |              ^^^^^^^^^^^^^^^^^^^^^ sharing memory with a native function
+   |
+   = help: when memory is shared with a native function call, Miri can only track initialisation and provenance on a best-effort basis
+   = help: in particular, Miri assumes that the native call initializes all memory it has written to
+   = help: Miri also assumes that any part of this memory may be a pointer that is permitted to point to arbitrary exposed memory
+   = help: what this means is that Miri will easily miss Undefined Behavior related to incorrect usage of this shared memory, so you should not take a clean Miri run as a signal that your FFI code is UB-free
+   = help: tracing memory accesses in native code is not yet fully implemented, so there can be further imprecisions beyond what is documented here
+   = note: BACKTRACE:
+   = note: inside `test_increment_int` at tests/native-lib/pass/ptr_write_access.rs:LL:CC
+note: inside `main`
+  --> tests/native-lib/pass/ptr_write_access.rs:LL:CC
+   |
+LL |     test_increment_int();
+   |     ^^^^^^^^^^^^^^^^^^^^
+
diff --git a/src/tools/miri/tests/native-lib/ptr_read_access.c b/src/tools/miri/tests/native-lib/ptr_read_access.c
index b89126d3d7c..021eb6adca4 100644
--- a/src/tools/miri/tests/native-lib/ptr_read_access.c
+++ b/src/tools/miri/tests/native-lib/ptr_read_access.c
@@ -49,3 +49,9 @@ typedef struct Static {
 EXPORT int32_t access_static(const Static *s_ptr) {
   return s_ptr->recurse->recurse->value;
 }
+
+/* Test: unexposed_reachable_alloc */
+
+EXPORT uintptr_t do_one_deref(const int32_t ***ptr) {
+  return (uintptr_t)*ptr;
+}
diff --git a/src/tools/miri/tests/native-lib/ptr_write_access.c b/src/tools/miri/tests/native-lib/ptr_write_access.c
index fd8b005499c..5260d0b3651 100644
--- a/src/tools/miri/tests/native-lib/ptr_write_access.c
+++ b/src/tools/miri/tests/native-lib/ptr_write_access.c
@@ -107,3 +107,11 @@ EXPORT void set_shared_mem(int32_t** ptr) {
 EXPORT void init_ptr_stored_in_shared_mem(int32_t val) {
   **shared_place = val;
 }
+
+/* Test: partial_init */
+
+EXPORT void init_n(int32_t n, char* ptr) {
+  for (int i=0; i<n; i++) {
+    *(ptr+i) = 0;
+  }
+}
diff --git a/src/tools/miri/tests/panic/mir-validation.stderr b/src/tools/miri/tests/panic/mir-validation.stderr
index dc70d129da3..f801ac907e6 100644
--- a/src/tools/miri/tests/panic/mir-validation.stderr
+++ b/src/tools/miri/tests/panic/mir-validation.stderr
@@ -1,11 +1,15 @@
+error: internal compiler error: compiler/rustc_mir_transform/src/validate.rs:LL:CC: broken MIR in Item(DefId) (after phase change to runtime-optimized) at bb0[1]:
+                                place (*(_2.0: *mut i32)) has deref as a later projection (it is only permitted as the first projection)
+  --> tests/panic/mir-validation.rs:LL:CC
+   |
+LL |             *(tuple.0) = 1;
+   |             ^^^^^^^^^^^^^^
+
 
 thread 'rustc' panicked at compiler/rustc_mir_transform/src/validate.rs:LL:CC:
-broken MIR in Item(DefId) (after phase change to runtime-optimized) at bb0[1]:
-place (*(_2.0: *mut i32)) has deref as a later projection (it is only permitted as the first projection)
+Box<dyn Any>
 stack backtrace:
 
-error: the compiler unexpectedly panicked. this is a bug.
-
 
 
 
@@ -20,3 +24,5 @@ LL |     extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 
+error: aborting due to 1 previous error
+
diff --git a/src/tools/miri/tests/pass-dep/libc/libc-time.rs b/src/tools/miri/tests/pass-dep/libc/libc-time.rs
index e8957846ad5..9e9fadfca9e 100644
--- a/src/tools/miri/tests/pass-dep/libc/libc-time.rs
+++ b/src/tools/miri/tests/pass-dep/libc/libc-time.rs
@@ -336,7 +336,7 @@ fn test_nanosleep() {
     let remainder = ptr::null_mut::<libc::timespec>();
     let is_error = unsafe { libc::nanosleep(&duration_zero, remainder) };
     assert_eq!(is_error, 0);
-    assert!(start_test_sleep.elapsed() < Duration::from_millis(10));
+    assert!(start_test_sleep.elapsed() < Duration::from_millis(100));
 
     let start_test_sleep = Instant::now();
     let duration_100_millis = libc::timespec { tv_sec: 0, tv_nsec: 1_000_000_000 / 10 };
@@ -390,7 +390,7 @@ mod test_clock_nanosleep {
             )
         };
         assert_eq!(error, 0);
-        assert!(start_test_sleep.elapsed() < Duration::from_millis(10));
+        assert!(start_test_sleep.elapsed() < Duration::from_millis(100));
 
         let start_test_sleep = Instant::now();
         let hunderd_millis_after_start = add_100_millis(timespec_now(libc::CLOCK_MONOTONIC));
@@ -417,7 +417,7 @@ mod test_clock_nanosleep {
             libc::clock_nanosleep(libc::CLOCK_MONOTONIC, NO_FLAGS, &duration_zero, remainder)
         };
         assert_eq!(error, 0);
-        assert!(start_test_sleep.elapsed() < Duration::from_millis(10));
+        assert!(start_test_sleep.elapsed() < Duration::from_millis(100));
 
         let start_test_sleep = Instant::now();
         let duration_100_millis = libc::timespec { tv_sec: 0, tv_nsec: 1_000_000_000 / 10 };
diff --git a/src/tools/miri/tests/pass/0weak_memory_consistency.rs b/src/tools/miri/tests/pass/0weak_memory_consistency.rs
index b33aefaf1d5..e4ed9675de8 100644
--- a/src/tools/miri/tests/pass/0weak_memory_consistency.rs
+++ b/src/tools/miri/tests/pass/0weak_memory_consistency.rs
@@ -41,7 +41,15 @@ fn static_atomic_bool(val: bool) -> &'static AtomicBool {
 }
 
 /// Spins until it acquires a pre-determined value.
-fn loads_value(loc: &AtomicI32, ord: Ordering, val: i32) -> i32 {
+fn spin_until_i32(loc: &AtomicI32, ord: Ordering, val: i32) -> i32 {
+    while loc.load(ord) != val {
+        std::hint::spin_loop();
+    }
+    val
+}
+
+/// Spins until it acquires a pre-determined boolean.
+fn spin_until_bool(loc: &AtomicBool, ord: Ordering, val: bool) -> bool {
     while loc.load(ord) != val {
         std::hint::spin_loop();
     }
@@ -65,7 +73,7 @@ fn test_corr() {
     }); //                                           |                    |
     #[rustfmt::skip] //                              |synchronizes-with   |happens-before
     let j3 = spawn(move || { //                      |                    |
-        loads_value(&y, Acquire, 1); // <------------+                    |
+        spin_until_i32(&y, Acquire, 1); // <---------+                    |
         x.load(Relaxed) // <----------------------------------------------+
         // The two reads on x are ordered by hb, so they cannot observe values
         // differently from the modification order. If the first read observed
@@ -90,12 +98,12 @@ fn test_wrc() {
     }); //                                           |                     |
     #[rustfmt::skip] //                              |synchronizes-with    |
     let j2 = spawn(move || { //                      |                     |
-        loads_value(&x, Acquire, 1); // <------------+                     |
+        spin_until_i32(&x, Acquire, 1); // <---------+                     |
         y.store(1, Release); // ---------------------+                     |happens-before
     }); //                                           |                     |
     #[rustfmt::skip] //                              |synchronizes-with    |
     let j3 = spawn(move || { //                      |                     |
-        loads_value(&y, Acquire, 1); // <------------+                     |
+        spin_until_i32(&y, Acquire, 1); // <---------+                     |
         x.load(Relaxed) // <-----------------------------------------------+
     });
 
@@ -121,7 +129,7 @@ fn test_message_passing() {
     #[rustfmt::skip] //                              |synchronizes-with  | happens-before
     let j2 = spawn(move || { //                      |                   |
         let x = x; // avoid field capturing          |                   |
-        loads_value(&y, Acquire, 1); // <------------+                   |
+        spin_until_i32(&y, Acquire, 1); // <---------+                   |
         unsafe { *x.0 } // <---------------------------------------------+
     });
 
@@ -216,12 +224,12 @@ fn test_sync_through_rmw_and_fences() {
     let go = static_atomic_bool(false);
 
     let t1 = spawn(move || {
-        while !go.load(Relaxed) {}
+        spin_until_bool(go, Relaxed, true);
         rdmw(y, x, z)
     });
 
     let t2 = spawn(move || {
-        while !go.load(Relaxed) {}
+        spin_until_bool(go, Relaxed, true);
         rdmw(z, x, y)
     });
 
diff --git a/src/tools/miri/tests/pass/0weak_memory_consistency_sc.rs b/src/tools/miri/tests/pass/0weak_memory_consistency_sc.rs
index 45cc5e6e722..937c2a8cf28 100644
--- a/src/tools/miri/tests/pass/0weak_memory_consistency_sc.rs
+++ b/src/tools/miri/tests/pass/0weak_memory_consistency_sc.rs
@@ -20,7 +20,15 @@ fn static_atomic_bool(val: bool) -> &'static AtomicBool {
 }
 
 /// Spins until it acquires a pre-determined value.
-fn loads_value(loc: &AtomicI32, ord: Ordering, val: i32) -> i32 {
+fn spin_until_i32(loc: &AtomicI32, ord: Ordering, val: i32) -> i32 {
+    while loc.load(ord) != val {
+        std::hint::spin_loop();
+    }
+    val
+}
+
+/// Spins until it acquires a pre-determined boolean.
+fn spin_until_bool(loc: &AtomicBool, ord: Ordering, val: bool) -> bool {
     while loc.load(ord) != val {
         std::hint::spin_loop();
     }
@@ -60,11 +68,11 @@ fn test_iriw_sc_rlx() {
     let a = spawn(move || x.store(true, Relaxed));
     let b = spawn(move || y.store(true, Relaxed));
     let c = spawn(move || {
-        while !x.load(SeqCst) {}
+        spin_until_bool(x, SeqCst, true);
         y.load(SeqCst)
     });
     let d = spawn(move || {
-        while !y.load(SeqCst) {}
+        spin_until_bool(y, SeqCst, true);
         x.load(SeqCst)
     });
 
@@ -136,7 +144,7 @@ fn test_cpp20_rwc_syncs() {
     });
 
     let j2 = spawn(move || {
-        loads_value(&x, Relaxed, 1);
+        spin_until_i32(&x, Relaxed, 1);
         fence(SeqCst);
         y.load(Relaxed)
     });
diff --git a/src/tools/miri/tests/pass/alloc-access-tracking.rs b/src/tools/miri/tests/pass/alloc-access-tracking.rs
index 0e88951dc43..9eba0ca171b 100644
--- a/src/tools/miri/tests/pass/alloc-access-tracking.rs
+++ b/src/tools/miri/tests/pass/alloc-access-tracking.rs
@@ -1,7 +1,7 @@
 #![no_std]
 #![no_main]
-//@compile-flags: -Zmiri-track-alloc-id=20 -Zmiri-track-alloc-accesses -Cpanic=abort
-//@normalize-stderr-test: "id 20" -> "id $$ALLOC"
+//@compile-flags: -Zmiri-track-alloc-id=19 -Zmiri-track-alloc-accesses -Cpanic=abort
+//@normalize-stderr-test: "id 19" -> "id $$ALLOC"
 //@only-target: linux # alloc IDs differ between OSes (due to extern static allocations)
 
 extern "Rust" {
diff --git a/src/tools/miri/tests/pass/intrinsics/portable-simd.rs b/src/tools/miri/tests/pass/intrinsics/portable-simd.rs
index 726d4c01cc3..e2cd08733af 100644
--- a/src/tools/miri/tests/pass/intrinsics/portable-simd.rs
+++ b/src/tools/miri/tests/pass/intrinsics/portable-simd.rs
@@ -349,12 +349,15 @@ fn simd_mask() {
     // Non-power-of-2 multi-byte mask.
     #[repr(simd, packed)]
     #[allow(non_camel_case_types)]
-    #[derive(Copy, Clone, Debug, PartialEq)]
+    #[derive(Copy, Clone)]
     struct i32x10([i32; 10]);
     impl i32x10 {
         fn splat(x: i32) -> Self {
             Self([x; 10])
         }
+        fn into_array(self) -> [i32; 10] {
+            unsafe { std::mem::transmute(self) }
+        }
     }
     unsafe {
         let mask = i32x10([!0, !0, 0, !0, 0, 0, !0, 0, !0, 0]);
@@ -377,19 +380,22 @@ fn simd_mask() {
             i32x10::splat(!0), // yes
             i32x10::splat(0),  // no
         );
-        assert_eq!(selected1, mask);
-        assert_eq!(selected2, mask);
+        assert_eq!(selected1.into_array(), mask.into_array());
+        assert_eq!(selected2.into_array(), mask.into_array());
     }
 
     // Test for a mask where the next multiple of 8 is not a power of two.
     #[repr(simd, packed)]
     #[allow(non_camel_case_types)]
-    #[derive(Copy, Clone, Debug, PartialEq)]
+    #[derive(Copy, Clone)]
     struct i32x20([i32; 20]);
     impl i32x20 {
         fn splat(x: i32) -> Self {
             Self([x; 20])
         }
+        fn into_array(self) -> [i32; 20] {
+            unsafe { std::mem::transmute(self) }
+        }
     }
     unsafe {
         let mask = i32x20([!0, !0, 0, !0, 0, 0, !0, 0, !0, 0, 0, 0, 0, !0, !0, !0, !0, !0, !0, !0]);
@@ -419,8 +425,8 @@ fn simd_mask() {
             i32x20::splat(!0), // yes
             i32x20::splat(0),  // no
         );
-        assert_eq!(selected1, mask);
-        assert_eq!(selected2, mask);
+        assert_eq!(selected1.into_array(), mask.into_array());
+        assert_eq!(selected2.into_array(), mask.into_array());
     }
 }
 
@@ -708,12 +714,12 @@ fn simd_ops_non_pow2() {
     let x = SimdPacked([1u32; 3]);
     let y = SimdPacked([2u32; 3]);
     let z = unsafe { intrinsics::simd_add(x, y) };
-    assert_eq!({ z.0 }, [3u32; 3]);
+    assert_eq!(unsafe { *(&raw const z).cast::<[u32; 3]>() }, [3u32; 3]);
 
     let x = SimdPadded([1u32; 3]);
     let y = SimdPadded([2u32; 3]);
     let z = unsafe { intrinsics::simd_add(x, y) };
-    assert_eq!(z.0, [3u32; 3]);
+    assert_eq!(unsafe { *(&raw const z).cast::<[u32; 3]>() }, [3u32; 3]);
 }
 
 fn main() {
diff --git a/src/tools/miri/tests/pass/intrinsics/type-id.rs b/src/tools/miri/tests/pass/intrinsics/type-id.rs
new file mode 100644
index 00000000000..123fdbdc9ce
--- /dev/null
+++ b/src/tools/miri/tests/pass/intrinsics/type-id.rs
@@ -0,0 +1,19 @@
+use std::any::{Any, TypeId};
+
+fn main() {
+    let t1 = TypeId::of::<u64>();
+    let t2 = TypeId::of::<u64>();
+    assert_eq!(t1, t2);
+    let t3 = TypeId::of::<usize>();
+    assert_ne!(t1, t3);
+
+    let _ = format!("{t1:?}"); // test that we can debug-print
+
+    let b = Box::new(0u64) as Box<dyn Any>;
+    assert_eq!(*b.downcast_ref::<u64>().unwrap(), 0);
+    assert!(b.downcast_ref::<usize>().is_none());
+
+    // Get the first pointer chunk and try to make it a ZST ref.
+    // This used to trigger an error because TypeId allocs got misclassified as "LiveData".
+    let _raw_chunk = unsafe { (&raw const t1).cast::<&()>().read() };
+}
diff --git a/src/tools/miri/tests/pass/shims/ctor.rs b/src/tools/miri/tests/pass/shims/ctor.rs
new file mode 100644
index 00000000000..b997d2386b8
--- /dev/null
+++ b/src/tools/miri/tests/pass/shims/ctor.rs
@@ -0,0 +1,46 @@
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+static COUNT: AtomicUsize = AtomicUsize::new(0);
+
+unsafe extern "C" fn ctor() {
+    COUNT.fetch_add(1, Ordering::Relaxed);
+}
+
+#[rustfmt::skip]
+macro_rules! ctor {
+    ($ident:ident = $ctor:ident) => {
+        #[cfg_attr(
+            all(any(
+                target_os = "linux",
+                target_os = "android",
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "haiku",
+                target_os = "illumos",
+                target_os = "netbsd",
+                target_os = "openbsd",
+                target_os = "solaris",
+                target_os = "none",
+                target_family = "wasm",
+            )),
+            link_section = ".init_array"
+        )]
+        #[cfg_attr(windows, link_section = ".CRT$XCU")]
+        #[cfg_attr(
+            any(target_os = "macos", target_os = "ios"),
+            // We do not set the `mod_init_funcs` flag here since ctor/inventory also do not do
+            // that. See <https://github.com/rust-lang/miri/pull/4459#discussion_r2200115629>.
+            link_section = "__DATA,__mod_init_func"
+        )]
+        #[used]
+        static $ident: unsafe extern "C" fn() = $ctor;
+    };
+}
+
+ctor! { CTOR1 = ctor }
+ctor! { CTOR2 = ctor }
+ctor! { CTOR3 = ctor }
+
+fn main() {
+    assert_eq!(COUNT.load(Ordering::Relaxed), 3, "ctors did not run");
+}
diff --git a/src/tools/miri/tests/pass/weak_memory/weak.rs b/src/tools/miri/tests/pass/weak_memory/weak.rs
index eeab4ebf129..199f83f0528 100644
--- a/src/tools/miri/tests/pass/weak_memory/weak.rs
+++ b/src/tools/miri/tests/pass/weak_memory/weak.rs
@@ -24,7 +24,7 @@ fn static_atomic(val: usize) -> &'static AtomicUsize {
 }
 
 // Spins until it reads the given value
-fn reads_value(loc: &AtomicUsize, val: usize) -> usize {
+fn spin_until(loc: &AtomicUsize, val: usize) -> usize {
     while loc.load(Relaxed) != val {
         std::hint::spin_loop();
     }
@@ -85,7 +85,7 @@ fn initialization_write(add_fence: bool) -> bool {
     });
 
     let j2 = spawn(move || {
-        reads_value(wait, 1);
+        spin_until(wait, 1);
         if add_fence {
             fence(AcqRel);
         }
@@ -119,12 +119,12 @@ fn faa_replaced_by_load() -> bool {
     let go = static_atomic(0);
 
     let t1 = spawn(move || {
-        while go.load(Relaxed) == 0 {}
+        spin_until(go, 1);
         rdmw(y, x, z)
     });
 
     let t2 = spawn(move || {
-        while go.load(Relaxed) == 0 {}
+        spin_until(go, 1);
         rdmw(z, x, y)
     });
 
diff --git a/src/tools/opt-dist/src/environment.rs b/src/tools/opt-dist/src/environment.rs
index 946e926a3c0..d41dc80e6b2 100644
--- a/src/tools/opt-dist/src/environment.rs
+++ b/src/tools/opt-dist/src/environment.rs
@@ -27,6 +27,7 @@ pub struct Environment {
     shared_llvm: bool,
     run_tests: bool,
     fast_try_build: bool,
+    build_llvm: bool,
 }
 
 impl Environment {
@@ -111,6 +112,10 @@ impl Environment {
     pub fn is_fast_try_build(&self) -> bool {
         self.fast_try_build
     }
+
+    pub fn build_llvm(&self) -> bool {
+        self.build_llvm
+    }
 }
 
 /// What is the extension of binary executables on this platform?
diff --git a/src/tools/opt-dist/src/exec.rs b/src/tools/opt-dist/src/exec.rs
index 0dc6e56b9d5..56eff2ca2a7 100644
--- a/src/tools/opt-dist/src/exec.rs
+++ b/src/tools/opt-dist/src/exec.rs
@@ -139,8 +139,10 @@ impl Bootstrap {
         self
     }
 
-    pub fn llvm_pgo_optimize(mut self, profile: &LlvmPGOProfile) -> Self {
-        self.cmd = self.cmd.arg("--llvm-profile-use").arg(profile.0.as_str());
+    pub fn llvm_pgo_optimize(mut self, profile: Option<&LlvmPGOProfile>) -> Self {
+        if let Some(prof) = profile {
+            self.cmd = self.cmd.arg("--llvm-profile-use").arg(prof.0.as_str());
+        }
         self
     }
 
@@ -174,8 +176,10 @@ impl Bootstrap {
         self
     }
 
-    pub fn with_bolt_profile(mut self, profile: BoltProfile) -> Self {
-        self.cmd = self.cmd.arg("--reproducible-artifact").arg(profile.0.as_str());
+    pub fn with_bolt_profile(mut self, profile: Option<BoltProfile>) -> Self {
+        if let Some(prof) = profile {
+            self.cmd = self.cmd.arg("--reproducible-artifact").arg(prof.0.as_str());
+        }
         self
     }
 
diff --git a/src/tools/opt-dist/src/main.rs b/src/tools/opt-dist/src/main.rs
index 9c8a6637a3b..7857f196626 100644
--- a/src/tools/opt-dist/src/main.rs
+++ b/src/tools/opt-dist/src/main.rs
@@ -98,6 +98,10 @@ enum EnvironmentCmd {
         /// Perform tests after final build if it's not a fast try build
         #[arg(long)]
         run_tests: bool,
+
+        /// Will be LLVM built during the run?
+        #[arg(long, default_value_t = true, action(clap::ArgAction::Set))]
+        build_llvm: bool,
     },
     /// Perform an optimized build on Linux CI, from inside Docker.
     LinuxCi {
@@ -133,6 +137,7 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
             benchmark_cargo_config,
             shared,
             run_tests,
+            build_llvm,
         } => {
             let env = EnvironmentBuilder::default()
                 .host_tuple(target_triple)
@@ -148,6 +153,7 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
                 .benchmark_cargo_config(benchmark_cargo_config)
                 .run_tests(run_tests)
                 .fast_try_build(is_fast_try_build)
+                .build_llvm(build_llvm)
                 .build()?;
 
             (env, shared.build_args)
@@ -172,6 +178,7 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
                 .skipped_tests(vec![])
                 .run_tests(true)
                 .fast_try_build(is_fast_try_build)
+                .build_llvm(true)
                 .build()?;
 
             (env, shared.build_args)
@@ -193,6 +200,7 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
                 .skipped_tests(vec![])
                 .run_tests(true)
                 .fast_try_build(is_fast_try_build)
+                .build_llvm(true)
                 .build()?;
 
             (env, shared.build_args)
@@ -255,30 +263,35 @@ fn execute_pipeline(
     // Stage 2: Gather LLVM PGO profiles
     // Here we build a PGO instrumented LLVM, reusing the previously PGO optimized rustc.
     // Then we use the instrumented LLVM to gather LLVM PGO profiles.
-    let llvm_pgo_profile = timer.section("Stage 2 (LLVM PGO)", |stage| {
-        // Remove the previous, uninstrumented build of LLVM.
-        clear_llvm_files(env)?;
+    let llvm_pgo_profile = if env.build_llvm() {
+        timer.section("Stage 2 (LLVM PGO)", |stage| {
+            // Remove the previous, uninstrumented build of LLVM.
+            clear_llvm_files(env)?;
 
-        let llvm_profile_dir_root = env.artifact_dir().join("llvm-pgo");
+            let llvm_profile_dir_root = env.artifact_dir().join("llvm-pgo");
 
-        stage.section("Build PGO instrumented LLVM", |section| {
-            Bootstrap::build(env)
-                .llvm_pgo_instrument(&llvm_profile_dir_root)
-                .avoid_rustc_rebuild()
-                .run(section)
-        })?;
+            stage.section("Build PGO instrumented LLVM", |section| {
+                Bootstrap::build(env)
+                    .llvm_pgo_instrument(&llvm_profile_dir_root)
+                    .avoid_rustc_rebuild()
+                    .run(section)
+            })?;
 
-        let profile = stage
-            .section("Gather profiles", |_| gather_llvm_profiles(env, &llvm_profile_dir_root))?;
+            let profile = stage.section("Gather profiles", |_| {
+                gather_llvm_profiles(env, &llvm_profile_dir_root)
+            })?;
 
-        print_free_disk_space()?;
+            print_free_disk_space()?;
 
-        // Proactively delete the instrumented artifacts, to avoid using them by accident in
-        // follow-up stages.
-        clear_llvm_files(env)?;
+            // Proactively delete the instrumented artifacts, to avoid using them by accident in
+            // follow-up stages.
+            clear_llvm_files(env)?;
 
-        Ok(profile)
-    })?;
+            Ok(Some(profile))
+        })?
+    } else {
+        None
+    };
 
     let bolt_profiles = if env.use_bolt() {
         // Stage 3: Build BOLT instrumented LLVM
@@ -286,37 +299,43 @@ fn execute_pipeline(
         // Note that we don't remove LLVM artifacts after this step, so that they are reused in the final dist build.
         // BOLT instrumentation is performed "on-the-fly" when the LLVM library is copied to the sysroot of rustc,
         // therefore the LLVM artifacts on disk are not "tainted" with BOLT instrumentation and they can be reused.
+        let libdir = env.build_artifacts().join("stage2").join("lib");
         timer.section("Stage 3 (BOLT)", |stage| {
-            stage.section("Build PGO optimized LLVM", |stage| {
-                Bootstrap::build(env)
-                    .with_llvm_bolt_ldflags()
-                    .llvm_pgo_optimize(&llvm_pgo_profile)
-                    .avoid_rustc_rebuild()
-                    .run(stage)
-            })?;
-
-            let libdir = env.build_artifacts().join("stage2").join("lib");
-            // The actual name will be something like libLLVM.so.18.1-rust-dev.
-            let llvm_lib = io::find_file_in_dir(&libdir, "libLLVM.so", "")?;
-
-            log::info!("Optimizing {llvm_lib} with BOLT");
-
-            // FIXME(kobzol): try gather profiles together, at once for LLVM and rustc
-            // Instrument the libraries and gather profiles
-            let llvm_profile = with_bolt_instrumented(&llvm_lib, |llvm_profile_dir| {
-                stage.section("Gather profiles", |_| {
-                    gather_bolt_profiles(env, "LLVM", llvm_benchmarks(env), llvm_profile_dir)
-                })
-            })?;
-            print_free_disk_space()?;
-
-            // Now optimize the library with BOLT. The `libLLVM-XXX.so` library is actually hard-linked
-            // from several places, and this specific path (`llvm_lib`) will *not* be packaged into
-            // the final dist build. However, when BOLT optimizes an artifact, it does so *in-place*,
-            // therefore it will actually optimize all the hard links, which means that the final
-            // packaged `libLLVM.so` file *will* be BOLT optimized.
-            bolt_optimize(&llvm_lib, &llvm_profile, env)
-                .context("Could not optimize LLVM with BOLT")?;
+            let llvm_profile = if env.build_llvm() {
+                stage.section("Build PGO optimized LLVM", |stage| {
+                    Bootstrap::build(env)
+                        .with_llvm_bolt_ldflags()
+                        .llvm_pgo_optimize(llvm_pgo_profile.as_ref())
+                        .avoid_rustc_rebuild()
+                        .run(stage)
+                })?;
+
+                // The actual name will be something like libLLVM.so.18.1-rust-dev.
+                let llvm_lib = io::find_file_in_dir(&libdir, "libLLVM.so", "")?;
+
+                log::info!("Optimizing {llvm_lib} with BOLT");
+
+                // FIXME(kobzol): try gather profiles together, at once for LLVM and rustc
+                // Instrument the libraries and gather profiles
+                let llvm_profile = with_bolt_instrumented(&llvm_lib, |llvm_profile_dir| {
+                    stage.section("Gather profiles", |_| {
+                        gather_bolt_profiles(env, "LLVM", llvm_benchmarks(env), llvm_profile_dir)
+                    })
+                })?;
+                print_free_disk_space()?;
+
+                // Now optimize the library with BOLT. The `libLLVM-XXX.so` library is actually hard-linked
+                // from several places, and this specific path (`llvm_lib`) will *not* be packaged into
+                // the final dist build. However, when BOLT optimizes an artifact, it does so *in-place*,
+                // therefore it will actually optimize all the hard links, which means that the final
+                // packaged `libLLVM.so` file *will* be BOLT optimized.
+                bolt_optimize(&llvm_lib, &llvm_profile, env)
+                    .context("Could not optimize LLVM with BOLT")?;
+
+                Some(llvm_profile)
+            } else {
+                None
+            };
 
             let rustc_lib = io::find_file_in_dir(&libdir, "librustc_driver", ".so")?;
 
@@ -334,15 +353,16 @@ fn execute_pipeline(
             bolt_optimize(&rustc_lib, &rustc_profile, env)
                 .context("Could not optimize rustc with BOLT")?;
 
-            // LLVM is not being cleared here, we want to use the BOLT-optimized LLVM
-            Ok(vec![llvm_profile, rustc_profile])
+            // LLVM is not being cleared here. Either we built it and we want to use the BOLT-optimized LLVM, or we
+            // didn't build it, so we don't want to remove it.
+            Ok(vec![llvm_profile, Some(rustc_profile)])
         })?
     } else {
         vec![]
     };
 
     let mut dist = Bootstrap::dist(env, &dist_args)
-        .llvm_pgo_optimize(&llvm_pgo_profile)
+        .llvm_pgo_optimize(llvm_pgo_profile.as_ref())
         .rustc_pgo_optimize(&rustc_pgo_profile)
         .avoid_rustc_rebuild();
 
diff --git a/src/tools/opt-dist/src/training.rs b/src/tools/opt-dist/src/training.rs
index 36a7d6a7cba..ae062d5c60c 100644
--- a/src/tools/opt-dist/src/training.rs
+++ b/src/tools/opt-dist/src/training.rs
@@ -163,7 +163,9 @@ pub fn gather_rustc_profiles(
     let merged_profile = env.artifact_dir().join("rustc-pgo.profdata");
     log::info!("Merging Rustc PGO profiles to {merged_profile}");
 
-    merge_llvm_profiles(env, &merged_profile, profile_root, LlvmProfdata::Target)?;
+    let llvm_profdata = if env.build_llvm() { LlvmProfdata::Target } else { LlvmProfdata::Host };
+
+    merge_llvm_profiles(env, &merged_profile, profile_root, llvm_profdata)?;
     log_profile_stats("Rustc", &merged_profile, profile_root)?;
 
     // We don't need the individual .profraw files now that they have been merged
diff --git a/src/tools/remote-test-client/src/main.rs b/src/tools/remote-test-client/src/main.rs
index bda08423487..b9741431b50 100644
--- a/src/tools/remote-test-client/src/main.rs
+++ b/src/tools/remote-test-client/src/main.rs
@@ -335,7 +335,9 @@ fn run(support_lib_count: usize, exe: String, all_args: Vec<String>) {
         std::process::exit(code);
     } else {
         println!("died due to signal {}", code);
-        std::process::exit(3);
+        // Behave like bash and other tools and exit with 128 + the signal
+        // number. That way we can avoid special case code in other places.
+        std::process::exit(128 + code);
     }
 }
 
diff --git a/src/tools/run-make-support/src/symbols.rs b/src/tools/run-make-support/src/symbols.rs
index e4d244e14a4..0e11360bd5a 100644
--- a/src/tools/run-make-support/src/symbols.rs
+++ b/src/tools/run-make-support/src/symbols.rs
@@ -1,6 +1,7 @@
+use std::collections::BTreeSet;
 use std::path::Path;
 
-use object::{self, Object, ObjectSymbol, SymbolIterator};
+use object::{self, Object, ObjectSymbol};
 
 /// Given an [`object::File`], find the exported dynamic symbol names via
 /// [`object::Object::exports`]. This does not distinguish between which section the symbols appear
@@ -14,47 +15,180 @@ pub fn exported_dynamic_symbol_names<'file>(file: &'file object::File<'file>) ->
         .collect()
 }
 
-/// Iterate through the symbols in an object file. See [`object::Object::symbols`].
+/// Check an object file's symbols for any matching **substrings**. That is, if an object file
+/// contains a symbol named `hello_world`, it will be matched against a provided `substrings` of
+/// `["hello", "bar"]`.
+///
+/// Returns `true` if **any** of the symbols found in the object file at `path` contain a
+/// **substring** listed in `substrings`.
 ///
 /// Panics if `path` is not a valid object file readable by the current user or if `path` cannot be
 /// parsed as a recognized object file.
+///
+/// # Platform-specific behavior
+///
+/// On Windows MSVC, the binary (e.g. `main.exe`) does not contain the symbols, but in the separate
+/// PDB file instead. Furthermore, you will need to use [`crate::llvm::llvm_pdbutil`] as `object`
+/// crate does not handle PDB files.
 #[track_caller]
-pub fn with_symbol_iter<P, F, R>(path: P, func: F) -> R
+pub fn object_contains_any_symbol_substring<P, S>(path: P, substrings: &[S]) -> bool
 where
     P: AsRef<Path>,
-    F: FnOnce(&mut SymbolIterator<'_, '_>) -> R,
+    S: AsRef<str>,
 {
     let path = path.as_ref();
     let blob = crate::fs::read(path);
-    let f = object::File::parse(&*blob)
+    let obj = object::File::parse(&*blob)
         .unwrap_or_else(|e| panic!("failed to parse `{}`: {e}", path.display()));
-    let mut iter = f.symbols();
-    func(&mut iter)
+    let substrings = substrings.iter().map(|s| s.as_ref()).collect::<Vec<_>>();
+    for sym in obj.symbols() {
+        for substring in &substrings {
+            if sym.name_bytes().unwrap().windows(substring.len()).any(|x| x == substring.as_bytes())
+            {
+                return true;
+            }
+        }
+    }
+    false
 }
 
-/// Check an object file's symbols for substrings.
+/// Check an object file's symbols for any exact matches against those provided in
+/// `candidate_symbols`.
 ///
-/// Returns `true` if any of the symbols found in the object file at `path` contain a substring
-/// listed in `substrings`.
+/// Returns `true` if **any** of the symbols found in the object file at `path` contain an **exact
+/// match** against those listed in `candidate_symbols`. Take care to account for (1) platform
+/// differences and (2) calling convention and symbol decorations differences.
 ///
 /// Panics if `path` is not a valid object file readable by the current user or if `path` cannot be
 /// parsed as a recognized object file.
+///
+/// # Platform-specific behavior
+///
+/// See [`object_contains_any_symbol_substring`].
 #[track_caller]
-pub fn any_symbol_contains(path: impl AsRef<Path>, substrings: &[&str]) -> bool {
-    with_symbol_iter(path, |syms| {
-        for sym in syms {
-            for substring in substrings {
-                if sym
-                    .name_bytes()
-                    .unwrap()
-                    .windows(substring.len())
-                    .any(|x| x == substring.as_bytes())
-                {
-                    eprintln!("{:?} contains {}", sym, substring);
-                    return true;
-                }
+pub fn object_contains_any_symbol<P, S>(path: P, candidate_symbols: &[S]) -> bool
+where
+    P: AsRef<Path>,
+    S: AsRef<str>,
+{
+    let path = path.as_ref();
+    let blob = crate::fs::read(path);
+    let obj = object::File::parse(&*blob)
+        .unwrap_or_else(|e| panic!("failed to parse `{}`: {e}", path.display()));
+    let candidate_symbols = candidate_symbols.iter().map(|s| s.as_ref()).collect::<Vec<_>>();
+    for sym in obj.symbols() {
+        for candidate_symbol in &candidate_symbols {
+            if sym.name_bytes().unwrap() == candidate_symbol.as_bytes() {
+                return true;
             }
         }
-        false
-    })
+    }
+    false
+}
+
+#[derive(Debug, PartialEq)]
+pub enum ContainsAllSymbolSubstringsOutcome<'a> {
+    Ok,
+    MissingSymbolSubstrings(BTreeSet<&'a str>),
+}
+
+/// Check an object file's symbols for presence of all of provided **substrings**. That is, if an
+/// object file contains symbols `["hello", "goodbye", "world"]`, it will be matched against a list
+/// of `substrings` of `["he", "go"]`. In this case, `he` is a substring of `hello`, and `go` is a
+/// substring of `goodbye`, so each of `substrings` was found.
+///
+/// Returns `true` if **all** `substrings` were present in the names of symbols for the given object
+/// file (as substrings of symbol names).
+///
+/// Panics if `path` is not a valid object file readable by the current user or if `path` cannot be
+/// parsed as a recognized object file.
+///
+/// # Platform-specific behavior
+///
+/// See [`object_contains_any_symbol_substring`].
+#[track_caller]
+pub fn object_contains_all_symbol_substring<'s, P, S>(
+    path: P,
+    substrings: &'s [S],
+) -> ContainsAllSymbolSubstringsOutcome<'s>
+where
+    P: AsRef<Path>,
+    S: AsRef<str>,
+{
+    let path = path.as_ref();
+    let blob = crate::fs::read(path);
+    let obj = object::File::parse(&*blob)
+        .unwrap_or_else(|e| panic!("failed to parse `{}`: {e}", path.display()));
+    let substrings = substrings.iter().map(|s| s.as_ref());
+    let mut unmatched_symbol_substrings = BTreeSet::from_iter(substrings);
+    unmatched_symbol_substrings.retain(|unmatched_symbol_substring| {
+        for sym in obj.symbols() {
+            if sym
+                .name_bytes()
+                .unwrap()
+                .windows(unmatched_symbol_substring.len())
+                .any(|x| x == unmatched_symbol_substring.as_bytes())
+            {
+                return false;
+            }
+        }
+
+        true
+    });
+
+    if unmatched_symbol_substrings.is_empty() {
+        ContainsAllSymbolSubstringsOutcome::Ok
+    } else {
+        ContainsAllSymbolSubstringsOutcome::MissingSymbolSubstrings(unmatched_symbol_substrings)
+    }
+}
+
+#[derive(Debug, PartialEq)]
+pub enum ContainsAllSymbolsOutcome<'a> {
+    Ok,
+    MissingSymbols(BTreeSet<&'a str>),
+}
+
+/// Check an object file contains all symbols provided in `candidate_symbols`.
+///
+/// Returns `true` if **all** of the symbols in `candidate_symbols` are found within the object file
+/// at `path` by **exact match**. Take care to account for (1) platform differences and (2) calling
+/// convention and symbol decorations differences.
+///
+/// Panics if `path` is not a valid object file readable by the current user or if `path` cannot be
+/// parsed as a recognized object file.
+///
+/// # Platform-specific behavior
+///
+/// See [`object_contains_any_symbol_substring`].
+#[track_caller]
+pub fn object_contains_all_symbols<P, S>(
+    path: P,
+    candidate_symbols: &[S],
+) -> ContainsAllSymbolsOutcome<'_>
+where
+    P: AsRef<Path>,
+    S: AsRef<str>,
+{
+    let path = path.as_ref();
+    let blob = crate::fs::read(path);
+    let obj = object::File::parse(&*blob)
+        .unwrap_or_else(|e| panic!("failed to parse `{}`: {e}", path.display()));
+    let candidate_symbols = candidate_symbols.iter().map(|s| s.as_ref());
+    let mut unmatched_symbols = BTreeSet::from_iter(candidate_symbols);
+    unmatched_symbols.retain(|unmatched_symbol| {
+        for sym in obj.symbols() {
+            if sym.name_bytes().unwrap() == unmatched_symbol.as_bytes() {
+                return false;
+            }
+        }
+
+        true
+    });
+
+    if unmatched_symbols.is_empty() {
+        ContainsAllSymbolsOutcome::Ok
+    } else {
+        ContainsAllSymbolsOutcome::MissingSymbols(unmatched_symbols)
+    }
 }
diff --git a/src/tools/rust-analyzer/Cargo.lock b/src/tools/rust-analyzer/Cargo.lock
index e55cd80943d..c471234bbe3 100644
--- a/src/tools/rust-analyzer/Cargo.lock
+++ b/src/tools/rust-analyzer/Cargo.lock
@@ -1268,7 +1268,7 @@ dependencies = [
  "expect-test",
  "intern",
  "parser",
- "ra-ap-rustc_lexer",
+ "ra-ap-rustc_lexer 0.122.0",
  "rustc-hash 2.1.1",
  "smallvec",
  "span",
@@ -1504,7 +1504,7 @@ dependencies = [
  "drop_bomb",
  "edition",
  "expect-test",
- "ra-ap-rustc_lexer",
+ "ra-ap-rustc_lexer 0.122.0",
  "rustc-literal-escaper",
  "stdx",
  "tracing",
@@ -1614,7 +1614,7 @@ dependencies = [
  "object",
  "paths",
  "proc-macro-test",
- "ra-ap-rustc_lexer",
+ "ra-ap-rustc_lexer 0.122.0",
  "span",
  "syntax-bridge",
  "tt",
@@ -1756,9 +1756,9 @@ dependencies = [
 
 [[package]]
 name = "ra-ap-rustc_abi"
-version = "0.121.0"
+version = "0.122.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ee51482d1c9d3e538acda8cce723db8eea1a81540544bf362bf4c3d841b2329"
+checksum = "fb01e1fec578003c85481c1cad4ff8cd8195b07c2dc85ae3f716108507ae15d5"
 dependencies = [
  "bitflags 2.9.1",
  "ra-ap-rustc_hashes",
@@ -1768,18 +1768,18 @@ dependencies = [
 
 [[package]]
 name = "ra-ap-rustc_hashes"
-version = "0.121.0"
+version = "0.122.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "19c8f1e0c28e24e1b4c55dc08058c6c9829df2204497d4034259f491d348c204"
+checksum = "e0ec056e72a472ffef8761ce96ece6c626eb07368c09d0105b6df30d27d07673"
 dependencies = [
  "rustc-stable-hash",
 ]
 
 [[package]]
 name = "ra-ap-rustc_index"
-version = "0.121.0"
+version = "0.122.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5f33f429cec6b92fa2c7243883279fb29dd233fdc3e94099aff32aa91aa87f50"
+checksum = "0fcdd1001db0295e59052e9f53aeda588bbe81e362534f4687d41bd44777b5a7"
 dependencies = [
  "ra-ap-rustc_index_macros",
  "smallvec",
@@ -1787,9 +1787,9 @@ dependencies = [
 
 [[package]]
 name = "ra-ap-rustc_index_macros"
-version = "0.121.0"
+version = "0.122.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b9b55910dbe1fe7ef34bdc1d1bcb41e99b377eb680ea58a1218d95d6b4152257"
+checksum = "728d64dd98e25530b32e3f7c7c1e844e52722b269360daa1cdeba9dff9727a26"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1808,20 +1808,31 @@ dependencies = [
 ]
 
 [[package]]
+name = "ra-ap-rustc_lexer"
+version = "0.122.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "415f0821f512608d825b3215489a6a6a2c18ed9f0045953d514e7ec23d4b90ab"
+dependencies = [
+ "memchr",
+ "unicode-properties",
+ "unicode-xid",
+]
+
+[[package]]
 name = "ra-ap-rustc_parse_format"
 version = "0.121.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "81057891bc2063ad9e353f29462fbc47a0f5072560af34428ae9313aaa5e9d97"
 dependencies = [
- "ra-ap-rustc_lexer",
+ "ra-ap-rustc_lexer 0.121.0",
  "rustc-literal-escaper",
 ]
 
 [[package]]
 name = "ra-ap-rustc_pattern_analysis"
-version = "0.121.0"
+version = "0.122.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fe21a3542980d56d2435e96c2720773cac1c63fd4db666417e414729da192eb3"
+checksum = "4657fcfdfe06e2a02ec8180d4e7c95aecf4811ba50367e363d1a2300b7623284"
 dependencies = [
  "ra-ap-rustc_index",
  "rustc-hash 2.1.1",
@@ -2581,7 +2592,7 @@ version = "0.0.0"
 dependencies = [
  "arrayvec",
  "intern",
- "ra-ap-rustc_lexer",
+ "ra-ap-rustc_lexer 0.122.0",
  "stdx",
  "text-size",
 ]
diff --git a/src/tools/rust-analyzer/Cargo.toml b/src/tools/rust-analyzer/Cargo.toml
index 41fa06a76a7..700c116ec18 100644
--- a/src/tools/rust-analyzer/Cargo.toml
+++ b/src/tools/rust-analyzer/Cargo.toml
@@ -89,11 +89,11 @@ vfs-notify = { path = "./crates/vfs-notify", version = "0.0.0" }
 vfs = { path = "./crates/vfs", version = "0.0.0" }
 edition = { path = "./crates/edition", version = "0.0.0" }
 
-ra-ap-rustc_lexer = { version = "0.121", default-features = false }
+ra-ap-rustc_lexer = { version = "0.122", default-features = false }
 ra-ap-rustc_parse_format = { version = "0.121", default-features = false }
-ra-ap-rustc_index = { version = "0.121", default-features = false }
-ra-ap-rustc_abi = { version = "0.121", default-features = false }
-ra-ap-rustc_pattern_analysis = { version = "0.121", default-features = false }
+ra-ap-rustc_index = { version = "0.122", default-features = false }
+ra-ap-rustc_abi = { version = "0.122", default-features = false }
+ra-ap-rustc_pattern_analysis = { version = "0.122", default-features = false }
 
 # local crates that aren't published to crates.io. These should not have versions.
 
diff --git a/src/tools/rust-analyzer/crates/test-utils/src/minicore.rs b/src/tools/rust-analyzer/crates/test-utils/src/minicore.rs
index 2b522598e2d..7b719b5dec7 100644
--- a/src/tools/rust-analyzer/crates/test-utils/src/minicore.rs
+++ b/src/tools/rust-analyzer/crates/test-utils/src/minicore.rs
@@ -1011,8 +1011,7 @@ pub mod ops {
     }
 
     #[lang = "add_assign"]
-    #[const_trait]
-    pub trait AddAssign<Rhs = Self> {
+    pub const trait AddAssign<Rhs = Self> {
         fn add_assign(&mut self, rhs: Rhs);
     }
 
diff --git a/src/tools/rust-analyzer/rust-version b/src/tools/rust-analyzer/rust-version
index 57ff326ce5a..c2b1c151b83 100644
--- a/src/tools/rust-analyzer/rust-version
+++ b/src/tools/rust-analyzer/rust-version
@@ -1 +1 @@
-a9fb6103b05c6ad6eee6bed4c0bb5a2e8e1024c6
+e05ab47e6c418fb2b9faa2eae9a7e70c65c98eaa
diff --git a/src/tools/rustbook/Cargo.lock b/src/tools/rustbook/Cargo.lock
index 050ddf47bae..e363668d462 100644
--- a/src/tools/rustbook/Cargo.lock
+++ b/src/tools/rustbook/Cargo.lock
@@ -19,9 +19,9 @@ dependencies = [
 
 [[package]]
 name = "ammonia"
-version = "4.1.0"
+version = "4.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ada2ee439075a3e70b6992fce18ac4e407cd05aea9ca3f75d2c0b0c20bbb364"
+checksum = "d6b346764dd0814805de8abf899fe03065bcee69bb1a4771c785817e39f3978f"
 dependencies = [
  "cssparser",
  "html5ever",
@@ -156,9 +156,9 @@ checksum = "46c5e41b57b8bba42a04676d81cb89e9ee8e859a1a66f80a5a72e1cb76b34d43"
 
 [[package]]
 name = "cc"
-version = "1.2.29"
+version = "1.2.30"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5c1599538de2394445747c8cf7935946e3cc27e9625f889d979bfb2aaf569362"
+checksum = "deec109607ca693028562ed836a5f1c4b8bd77755c4e132fc5ce11b0b6211ae7"
 dependencies = [
  "shlex",
 ]
@@ -185,9 +185,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.40"
+version = "4.5.41"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "40b6887a1d8685cebccf115538db5c0efe625ccac9696ad45c409d96566e910f"
+checksum = "be92d32e80243a54711e5d7ce823c35c41c9d929dc4ab58e1276f625841aadf9"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -195,9 +195,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.40"
+version = "4.5.41"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e0c66c08ce9f0c698cbce5c0279d0bb6ac936d8674174fe48f736533b964f59e"
+checksum = "707eab41e9622f9139419d573eca0900137718000c517d47da73045f54331c3d"
 dependencies = [
  "anstream",
  "anstyle",
@@ -208,18 +208,18 @@ dependencies = [
 
 [[package]]
 name = "clap_complete"
-version = "4.5.54"
+version = "4.5.55"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aad5b1b4de04fead402672b48897030eec1f3bfe1550776322f59f6d6e6a5677"
+checksum = "a5abde44486daf70c5be8b8f8f1b66c49f86236edf6fa2abadb4d961c4c6229a"
 dependencies = [
  "clap",
 ]
 
 [[package]]
 name = "clap_derive"
-version = "4.5.40"
+version = "4.5.41"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2c7947ae4cc3d851207c1adb5b5e260ff0cca11446b1d6d1423788e442257ce"
+checksum = "ef4f52386a59ca4c860f7393bcf8abd8dfd91ecccc0f774635ff68e92eeef491"
 dependencies = [
  "heck",
  "proc-macro2",
@@ -256,9 +256,9 @@ dependencies = [
 
 [[package]]
 name = "crc32fast"
-version = "1.4.2"
+version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a97769d94ddab943e4510d138150169a2758b5ef3eb191a9ee688de3e23ef7b3"
+checksum = "9481c1c90cbf2ac953f07c8d4a58aa3945c425b7185c9154d67a65e4230da511"
 dependencies = [
  "cfg-if",
 ]
@@ -582,12 +582,11 @@ checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
 [[package]]
 name = "html5ever"
-version = "0.31.0"
+version = "0.35.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "953cbbe631aae7fc0a112702ad5d3aaf09da38beaf45ea84610d6e1c358f569c"
+checksum = "55d958c2f74b664487a2035fe1dadb032c48718a03b63f3ab0b8537db8549ed4"
 dependencies = [
  "log",
- "mac",
  "markup5ever",
  "match_token",
 ]
@@ -863,9 +862,9 @@ checksum = "3e2e65a1a2e43cfcb47a895c4c8b10d1f4a61097f9f254f183aee60cad9c651d"
 
 [[package]]
 name = "markup5ever"
-version = "0.16.2"
+version = "0.35.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2e4cd8c02f18a011991a039855480c64d74291c5792fcc160d55d77dc4de4a39"
+checksum = "311fe69c934650f8f19652b3946075f0fc41ad8757dbb68f1ca14e7900ecc1c3"
 dependencies = [
  "log",
  "tendril",
@@ -874,9 +873,9 @@ dependencies = [
 
 [[package]]
 name = "match_token"
-version = "0.1.0"
+version = "0.35.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "88a9689d8d44bf9964484516275f5cd4c9b59457a6940c1d5d0ecbb94510a36b"
+checksum = "ac84fd3f360fcc43dc5f5d186f02a94192761a080e8bc58621ad4d12296a58cf"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -885,9 +884,9 @@ dependencies = [
 
 [[package]]
 name = "mdbook"
-version = "0.4.51"
+version = "0.4.52"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a87e65420ab45ca9c1b8cdf698f95b710cc826d373fa550f0f7fad82beac9328"
+checksum = "93c284d2855916af7c5919cf9ad897cfc77d3c2db6f55429c7cfb769182030ec"
 dependencies = [
  "ammonia",
  "anyhow",
@@ -1394,15 +1393,15 @@ dependencies = [
 
 [[package]]
 name = "rustix"
-version = "1.0.7"
+version = "1.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c71e83d6afe7ff64890ec6b71d6a69bb8a610ab78ce364b3352876bb4c801266"
+checksum = "11181fbabf243db407ef8df94a6ce0b2f9a733bd8be4ad02b4eda9602296cac8"
 dependencies = [
  "bitflags 2.9.1",
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys 0.59.0",
+ "windows-sys 0.60.2",
 ]
 
 [[package]]
@@ -1460,9 +1459,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.140"
+version = "1.0.141"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "20068b6e96dc6c9bd23e01df8827e6c7e1f2fddd43c21810382803c136b99373"
+checksum = "30b9eff21ebe718216c6ec64e1d9ac57087aad11efc64e32002bce4a0d4c03d3"
 dependencies = [
  "itoa",
  "memchr",
@@ -2103,9 +2102,9 @@ checksum = "271414315aff87387382ec3d271b52d7ae78726f5d44ac98b4f4030c91880486"
 
 [[package]]
 name = "winnow"
-version = "0.7.11"
+version = "0.7.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74c7b26e3480b707944fc872477815d29a8e429d2f93a1ce000f5fa84a15cbcd"
+checksum = "f3edebf492c8125044983378ecb5766203ad3b4c2f7a922bd7dd207f6d443e95"
 dependencies = [
  "memchr",
 ]
diff --git a/src/tools/rustbook/Cargo.toml b/src/tools/rustbook/Cargo.toml
index 69c0cfaf5c9..c7c6e39f157 100644
--- a/src/tools/rustbook/Cargo.toml
+++ b/src/tools/rustbook/Cargo.toml
@@ -15,6 +15,6 @@ mdbook-i18n-helpers = "0.3.3"
 mdbook-spec = { path = "../../doc/reference/mdbook-spec" }
 
 [dependencies.mdbook]
-version = "0.4.51"
+version = "0.4.52"
 default-features = false
 features = ["search"]
diff --git a/src/tools/rustdoc-gui-test/src/main.rs b/src/tools/rustdoc-gui-test/src/main.rs
index 0e35861fbf7..5b86bea8932 100644
--- a/src/tools/rustdoc-gui-test/src/main.rs
+++ b/src/tools/rustdoc-gui-test/src/main.rs
@@ -1,63 +1,15 @@
+use std::env;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::sync::Arc;
-use std::{env, fs};
 
+use build_helper::npm;
 use build_helper::util::try_run;
 use compiletest::directives::TestProps;
 use config::Config;
 
 mod config;
 
-fn get_browser_ui_test_version_inner(npm: &Path, global: bool) -> Option<String> {
-    let mut command = Command::new(&npm);
-    command.arg("list").arg("--parseable").arg("--long").arg("--depth=0");
-    if global {
-        command.arg("--global");
-    }
-    let lines = match command.output() {
-        Ok(output) => String::from_utf8_lossy(&output.stdout).into_owned(),
-        Err(e) => {
-            eprintln!(
-                "path to npm can be wrong, provided path: {npm:?}. Try to set npm path \
-            in bootstrap.toml in [build.npm]",
-            );
-            panic!("{:?}", e)
-        }
-    };
-    lines
-        .lines()
-        .find_map(|l| l.rsplit(':').next()?.strip_prefix("browser-ui-test@"))
-        .map(|v| v.to_owned())
-}
-
-fn get_browser_ui_test_version(npm: &Path) -> Option<String> {
-    get_browser_ui_test_version_inner(npm, false)
-        .or_else(|| get_browser_ui_test_version_inner(npm, true))
-}
-
-fn compare_browser_ui_test_version(installed_version: &str, src: &Path) {
-    match fs::read_to_string(
-        src.join("src/ci/docker/host-x86_64/x86_64-gnu-tools/browser-ui-test.version"),
-    ) {
-        Ok(v) => {
-            if v.trim() != installed_version {
-                eprintln!(
-                    "⚠️ Installed version of browser-ui-test (`{}`) is different than the \
-                     one used in the CI (`{}`)",
-                    installed_version, v
-                );
-                eprintln!(
-                    "You can install this version using `npm update browser-ui-test` or by using \
-                     `npm install browser-ui-test@{}`",
-                    v,
-                );
-            }
-        }
-        Err(e) => eprintln!("Couldn't find the CI browser-ui-test version: {:?}", e),
-    }
-}
-
 fn find_librs<P: AsRef<Path>>(path: P) -> Option<PathBuf> {
     for entry in walkdir::WalkDir::new(path) {
         let entry = entry.ok()?;
@@ -71,27 +23,6 @@ fn find_librs<P: AsRef<Path>>(path: P) -> Option<PathBuf> {
 fn main() -> Result<(), ()> {
     let config = Arc::new(Config::from_args(env::args().collect()));
 
-    // The goal here is to check if the necessary packages are installed, and if not, we
-    // panic.
-    match get_browser_ui_test_version(&config.npm) {
-        Some(version) => {
-            // We also check the version currently used in CI and emit a warning if it's not the
-            // same one.
-            compare_browser_ui_test_version(&version, &config.rust_src);
-        }
-        None => {
-            eprintln!(
-                r#"
-error: rustdoc-gui test suite cannot be run because npm `browser-ui-test` dependency is missing.
-
-If you want to install the `browser-ui-test` dependency, run `npm install browser-ui-test`
-"#,
-            );
-
-            panic!("Cannot run rustdoc-gui tests");
-        }
-    }
-
     let src_path = config.rust_src.join("tests/rustdoc-gui/src");
     for entry in src_path.read_dir().expect("read_dir call failed") {
         if let Ok(entry) = entry {
@@ -134,16 +65,12 @@ If you want to install the `browser-ui-test` dependency, run `npm install browse
         }
     }
 
-    let mut command = Command::new(&config.nodejs);
+    // FIXME(binarycat): once we get package.json in version control, this should be updated to install via that instead
+    let local_node_modules =
+        npm::install_one(&config.out_dir, &config.npm, "browser-ui-test", "0.21.1")
+            .expect("unable to install browser-ui-test");
 
-    if let Ok(current_dir) = env::current_dir() {
-        let local_node_modules = current_dir.join("node_modules");
-        if local_node_modules.exists() {
-            // Link the local node_modules if exists.
-            // This is useful when we run rustdoc-gui-test from outside of the source root.
-            env::set_var("NODE_PATH", local_node_modules);
-        }
-    }
+    let mut command = Command::new(&config.nodejs);
 
     command
         .arg(config.rust_src.join("src/tools/rustdoc-gui/tester.js"))
@@ -154,6 +81,12 @@ If you want to install the `browser-ui-test` dependency, run `npm install browse
         .arg("--tests-folder")
         .arg(config.rust_src.join("tests/rustdoc-gui"));
 
+    if local_node_modules.exists() {
+        // Link the local node_modules if exists.
+        // This is useful when we run rustdoc-gui-test from outside of the source root.
+        command.env("NODE_PATH", local_node_modules);
+    }
+
     for file in &config.goml_files {
         command.arg("--file").arg(file);
     }
diff --git a/src/tools/rustdoc-js/tester.js b/src/tools/rustdoc-js/tester.js
index f70fc917770..0baa179e16b 100644
--- a/src/tools/rustdoc-js/tester.js
+++ b/src/tools/rustdoc-js/tester.js
@@ -28,7 +28,14 @@ function readFile(filePath) {
 }
 
 function contentToDiffLine(key, value) {
-    return `"${key}": "${value}",`;
+    if (typeof value === "object" && !Array.isArray(value) && value !== null) {
+        const out = Object.entries(value)
+            .filter(([subKey, _]) => ["path", "name"].includes(subKey))
+            .map(([subKey, subValue]) => `"${subKey}": ${JSON.stringify(subValue)}`)
+            .join(", ");
+        return `"${key}": ${out},`;
+    }
+    return `"${key}": ${JSON.stringify(value)},`;
 }
 
 function shouldIgnoreField(fieldName) {
@@ -37,47 +44,61 @@ function shouldIgnoreField(fieldName) {
         fieldName === "proposeCorrectionTo";
 }
 
+function valueMapper(key, testOutput) {
+    const isAlias = testOutput["is_alias"];
+    let value = testOutput[key];
+    // To make our life easier, if there is a "parent" type, we add it to the path.
+    if (key === "path") {
+        if (testOutput["parent"] !== undefined) {
+            if (value.length > 0) {
+                value += "::" + testOutput["parent"]["name"];
+            } else {
+                value = testOutput["parent"]["name"];
+            }
+        } else if (testOutput["is_alias"]) {
+            value = valueMapper(key, testOutput["original"]);
+        }
+    } else if (isAlias && key === "alias") {
+        value = testOutput["name"];
+    } else if (isAlias && ["name"].includes(key)) {
+        value = testOutput["original"][key];
+    }
+    return value;
+}
+
 // This function is only called when no matching result was found and therefore will only display
 // the diff between the two items.
-function betterLookingDiff(entry, data) {
+function betterLookingDiff(expected, testOutput) {
     let output = " {\n";
-    const spaces = "     ";
-    for (const key in entry) {
-        if (!Object.prototype.hasOwnProperty.call(entry, key)) {
+    const spaces = "    ";
+    for (const key in expected) {
+        if (!Object.prototype.hasOwnProperty.call(expected, key)) {
             continue;
         }
-        if (!data || !Object.prototype.hasOwnProperty.call(data, key)) {
-            output += "-" + spaces + contentToDiffLine(key, entry[key]) + "\n";
+        if (!testOutput || !Object.prototype.hasOwnProperty.call(testOutput, key)) {
+            output += "-" + spaces + contentToDiffLine(key, expected[key]) + "\n";
             continue;
         }
-        const value = data[key];
-        if (value !== entry[key]) {
-            output += "-" + spaces + contentToDiffLine(key, entry[key]) + "\n";
+        const value = valueMapper(key, testOutput);
+        if (value !== expected[key]) {
+            output += "-" + spaces + contentToDiffLine(key, expected[key]) + "\n";
             output += "+" + spaces + contentToDiffLine(key, value) + "\n";
         } else {
-            output += spaces + contentToDiffLine(key, value) + "\n";
+            output += spaces + " " + contentToDiffLine(key, value) + "\n";
         }
     }
     return output + " }";
 }
 
-function lookForEntry(entry, data) {
-    return data.findIndex(data_entry => {
+function lookForEntry(expected, testOutput) {
+    return testOutput.findIndex(testOutputEntry => {
         let allGood = true;
-        for (const key in entry) {
-            if (!Object.prototype.hasOwnProperty.call(entry, key)) {
+        for (const key in expected) {
+            if (!Object.prototype.hasOwnProperty.call(expected, key)) {
                 continue;
             }
-            let value = data_entry[key];
-            // To make our life easier, if there is a "parent" type, we add it to the path.
-            if (key === "path" && data_entry["parent"] !== undefined) {
-                if (value.length > 0) {
-                    value += "::" + data_entry["parent"]["name"];
-                } else {
-                    value = data_entry["parent"]["name"];
-                }
-            }
-            if (value !== entry[key]) {
+            const value = valueMapper(key, testOutputEntry);
+            if (value !== expected[key]) {
                 allGood = false;
                 break;
             }
diff --git a/src/tools/rustfmt/src/items.rs b/src/tools/rustfmt/src/items.rs
index 1a3897b51cb..7084639aca9 100644
--- a/src/tools/rustfmt/src/items.rs
+++ b/src/tools/rustfmt/src/items.rs
@@ -1172,6 +1172,7 @@ pub(crate) fn format_trait(
         unreachable!();
     };
     let ast::Trait {
+        constness,
         is_auto,
         safety,
         ident,
@@ -1182,7 +1183,8 @@ pub(crate) fn format_trait(
 
     let mut result = String::with_capacity(128);
     let header = format!(
-        "{}{}{}trait ",
+        "{}{}{}{}trait ",
+        format_constness(constness),
         format_visibility(context, &item.vis),
         format_safety(safety),
         format_auto(is_auto),
diff --git a/src/tools/suggest-tests/Cargo.toml b/src/tools/suggest-tests/Cargo.toml
deleted file mode 100644
index d6f86078d7e..00000000000
--- a/src/tools/suggest-tests/Cargo.toml
+++ /dev/null
@@ -1,8 +0,0 @@
-[package]
-name = "suggest-tests"
-version = "0.1.0"
-edition = "2021"
-
-[dependencies]
-glob = "0.3.0"
-build_helper = { version = "0.1.0", path = "../../build_helper" }
diff --git a/src/tools/suggest-tests/src/dynamic_suggestions.rs b/src/tools/suggest-tests/src/dynamic_suggestions.rs
deleted file mode 100644
index f09720f1c91..00000000000
--- a/src/tools/suggest-tests/src/dynamic_suggestions.rs
+++ /dev/null
@@ -1,32 +0,0 @@
-use std::path::Path;
-
-use crate::Suggestion;
-
-type DynamicSuggestion = fn(&Path) -> Vec<Suggestion>;
-
-pub(crate) const DYNAMIC_SUGGESTIONS: &[DynamicSuggestion] = &[
-    |path: &Path| -> Vec<Suggestion> {
-        if path.starts_with("compiler/") || path.starts_with("library/") {
-            let path = path.components().take(2).collect::<Vec<_>>();
-
-            vec![Suggestion::with_single_path(
-                "test",
-                None,
-                &format!(
-                    "{}/{}",
-                    path[0].as_os_str().to_str().unwrap(),
-                    path[1].as_os_str().to_str().unwrap()
-                ),
-            )]
-        } else {
-            Vec::new()
-        }
-    },
-    |path: &Path| -> Vec<Suggestion> {
-        if path.starts_with("compiler/rustc_pattern_analysis") {
-            vec![Suggestion::new("test", None, &["tests/ui", "--test-args", "pattern"])]
-        } else {
-            Vec::new()
-        }
-    },
-];
diff --git a/src/tools/suggest-tests/src/lib.rs b/src/tools/suggest-tests/src/lib.rs
deleted file mode 100644
index cc1288c6b72..00000000000
--- a/src/tools/suggest-tests/src/lib.rs
+++ /dev/null
@@ -1,96 +0,0 @@
-use std::fmt::{self, Display};
-use std::path::Path;
-
-use dynamic_suggestions::DYNAMIC_SUGGESTIONS;
-use glob::Pattern;
-use static_suggestions::static_suggestions;
-
-mod dynamic_suggestions;
-mod static_suggestions;
-
-#[cfg(test)]
-mod tests;
-
-macro_rules! sug {
-    ($cmd:expr) => {
-        Suggestion::new($cmd, None, &[])
-    };
-
-    ($cmd:expr, $paths:expr) => {
-        Suggestion::new($cmd, None, $paths.as_slice())
-    };
-
-    ($cmd:expr, $stage:expr, $paths:expr) => {
-        Suggestion::new($cmd, Some($stage), $paths.as_slice())
-    };
-}
-
-pub(crate) use sug;
-
-pub fn get_suggestions<T: AsRef<str>>(modified_files: &[T]) -> Vec<Suggestion> {
-    let mut suggestions = Vec::new();
-
-    // static suggestions
-    for (globs, sugs) in static_suggestions().iter() {
-        let globs = globs
-            .iter()
-            .map(|glob| Pattern::new(glob).expect("Found invalid glob pattern!"))
-            .collect::<Vec<_>>();
-        let matches_some_glob = |file: &str| globs.iter().any(|glob| glob.matches(file));
-
-        if modified_files.iter().map(AsRef::as_ref).any(matches_some_glob) {
-            suggestions.extend_from_slice(sugs);
-        }
-    }
-
-    // dynamic suggestions
-    for sug in DYNAMIC_SUGGESTIONS {
-        for file in modified_files {
-            let sugs = sug(Path::new(file.as_ref()));
-
-            suggestions.extend_from_slice(&sugs);
-        }
-    }
-
-    suggestions.sort();
-    suggestions.dedup();
-
-    suggestions
-}
-
-#[derive(Clone, PartialOrd, Ord, PartialEq, Eq, Debug)]
-pub struct Suggestion {
-    pub cmd: String,
-    pub stage: Option<u32>,
-    pub paths: Vec<String>,
-}
-
-impl Suggestion {
-    pub fn new(cmd: &str, stage: Option<u32>, paths: &[&str]) -> Self {
-        Self { cmd: cmd.to_owned(), stage, paths: paths.iter().map(|p| p.to_string()).collect() }
-    }
-
-    pub fn with_single_path(cmd: &str, stage: Option<u32>, path: &str) -> Self {
-        Self::new(cmd, stage, &[path])
-    }
-}
-
-impl Display for Suggestion {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        write!(f, "{} ", self.cmd)?;
-
-        for path in &self.paths {
-            write!(f, "{} ", path)?;
-        }
-
-        if let Some(stage) = self.stage {
-            write!(f, "{}", stage)?;
-        } else {
-            // write a sentinel value here (in place of a stage) to be consumed
-            // by the shim in bootstrap, it will be read and ignored.
-            write!(f, "N/A")?;
-        }
-
-        Ok(())
-    }
-}
diff --git a/src/tools/suggest-tests/src/main.rs b/src/tools/suggest-tests/src/main.rs
deleted file mode 100644
index d84f8e9fa1b..00000000000
--- a/src/tools/suggest-tests/src/main.rs
+++ /dev/null
@@ -1,40 +0,0 @@
-use std::process::ExitCode;
-
-use build_helper::git::{GitConfig, get_git_modified_files};
-use suggest_tests::get_suggestions;
-
-fn main() -> ExitCode {
-    let modified_files = get_git_modified_files(
-        &GitConfig {
-            nightly_branch: &env("SUGGEST_TESTS_NIGHTLY_BRANCH"),
-            git_merge_commit_email: &env("SUGGEST_TESTS_MERGE_COMMIT_EMAIL"),
-        },
-        None,
-        &Vec::new(),
-    );
-    let modified_files = match modified_files {
-        Ok(files) => files,
-        Err(err) => {
-            eprintln!("Could not get modified files from git: \"{err}\"");
-            return ExitCode::FAILURE;
-        }
-    };
-
-    let suggestions = get_suggestions(&modified_files);
-
-    for sug in &suggestions {
-        println!("{sug}");
-    }
-
-    ExitCode::SUCCESS
-}
-
-fn env(key: &str) -> String {
-    match std::env::var(key) {
-        Ok(var) => var,
-        Err(err) => {
-            eprintln!("suggest-tests: failed to read environment variable {key}: {err}");
-            std::process::exit(1);
-        }
-    }
-}
diff --git a/src/tools/suggest-tests/src/static_suggestions.rs b/src/tools/suggest-tests/src/static_suggestions.rs
deleted file mode 100644
index d363d583b54..00000000000
--- a/src/tools/suggest-tests/src/static_suggestions.rs
+++ /dev/null
@@ -1,40 +0,0 @@
-use std::sync::OnceLock;
-
-use crate::{Suggestion, sug};
-
-// FIXME: perhaps this could use `std::lazy` when it is stabilized
-macro_rules! static_suggestions {
-    ($( [ $( $glob:expr ),* $(,)? ] => [ $( $suggestion:expr ),* $(,)? ] ),* $(,)? ) => {
-        pub(crate) fn static_suggestions() -> &'static [(Vec<&'static str>, Vec<Suggestion>)]
-        {
-            static S: OnceLock<Vec<(Vec<&'static str>, Vec<Suggestion>)>> = OnceLock::new();
-            S.get_or_init(|| vec![ $( (vec![ $($glob),* ], vec![ $($suggestion),* ]) ),*])
-        }
-    }
-}
-
-static_suggestions! {
-    ["*.md"] => [
-        sug!("test", 0, ["linkchecker"]),
-    ],
-
-    ["compiler/*"] => [
-        sug!("check"),
-        sug!("test", 1, ["tests/ui", "tests/run-make"]),
-    ],
-
-    ["compiler/rustc_mir_transform/*"] => [
-        sug!("test", 1, ["mir-opt"]),
-    ],
-
-    [
-        "compiler/rustc_mir_transform/src/coverage/*",
-        "compiler/rustc_codegen_llvm/src/coverageinfo/*",
-    ] => [
-        sug!("test", 1, ["coverage"]),
-    ],
-
-    ["src/librustdoc/*"] => [
-        sug!("test", 1, ["rustdoc"]),
-    ],
-}
diff --git a/src/tools/suggest-tests/src/tests.rs b/src/tools/suggest-tests/src/tests.rs
deleted file mode 100644
index b4149136fa3..00000000000
--- a/src/tools/suggest-tests/src/tests.rs
+++ /dev/null
@@ -1,21 +0,0 @@
-macro_rules! sugg_test {
-    ( $( $name:ident: $paths:expr => $suggestions:expr ),* ) => {
-        $(
-            #[test]
-            fn $name() {
-                let suggestions = crate::get_suggestions(&$paths).into_iter().map(|s| s.to_string()).collect::<Vec<_>>();
-                assert_eq!(suggestions, $suggestions);
-            }
-        )*
-    };
-}
-
-sugg_test! {
-    test_error_code_docs: ["compiler/rustc_error_codes/src/error_codes/E0000.md"] =>
-        ["check N/A", "test compiler/rustc_error_codes N/A", "test linkchecker 0", "test tests/ui tests/run-make 1"],
-
-    test_rustdoc: ["src/librustdoc/src/lib.rs"] => ["test rustdoc 1"],
-
-    test_rustdoc_and_libstd: ["src/librustdoc/src/lib.rs", "library/std/src/lib.rs"] =>
-        ["test library/std N/A", "test rustdoc 1"]
-}
diff --git a/src/tools/tidy/src/features.rs b/src/tools/tidy/src/features.rs
index e83b47e1380..fb00b3a943f 100644
--- a/src/tools/tidy/src/features.rs
+++ b/src/tools/tidy/src/features.rs
@@ -331,11 +331,9 @@ fn collect_lang_features_in(features: &mut Features, base: &Path, file: &str, ba
             continue;
         }
 
-        if in_feature_group {
-            if let Some(doc_comment) = line.strip_prefix("///") {
-                doc_comments.push(doc_comment.trim().to_string());
-                continue;
-            }
+        if in_feature_group && let Some(doc_comment) = line.strip_prefix("///") {
+            doc_comments.push(doc_comment.trim().to_string());
+            continue;
         }
 
         let mut parts = line.split(',');
@@ -465,19 +463,20 @@ fn get_and_check_lib_features(
     map_lib_features(base_src_path, &mut |res, file, line| match res {
         Ok((name, f)) => {
             let mut check_features = |f: &Feature, list: &Features, display: &str| {
-                if let Some(s) = list.get(name) {
-                    if f.tracking_issue != s.tracking_issue && f.level != Status::Accepted {
-                        tidy_error!(
-                            bad,
-                            "{}:{}: feature gate {} has inconsistent `issue`: \"{}\" mismatches the {} `issue` of \"{}\"",
-                            file.display(),
-                            line,
-                            name,
-                            f.tracking_issue_display(),
-                            display,
-                            s.tracking_issue_display(),
-                        );
-                    }
+                if let Some(s) = list.get(name)
+                    && f.tracking_issue != s.tracking_issue
+                    && f.level != Status::Accepted
+                {
+                    tidy_error!(
+                        bad,
+                        "{}:{}: feature gate {} has inconsistent `issue`: \"{}\" mismatches the {} `issue` of \"{}\"",
+                        file.display(),
+                        line,
+                        name,
+                        f.tracking_issue_display(),
+                        display,
+                        s.tracking_issue_display(),
+                    );
                 }
             };
             check_features(&f, lang_features, "corresponding lang feature");
diff --git a/src/tools/tidy/src/filenames.rs b/src/tools/tidy/src/filenames.rs
new file mode 100644
index 00000000000..53115f4eaa4
--- /dev/null
+++ b/src/tools/tidy/src/filenames.rs
@@ -0,0 +1,40 @@
+//! Tidy check to ensure that there are no filenames containing forbidden characters
+//! checked into the source tree by accident:
+//! - Non-UTF8 filenames
+//! - Control characters such as CR or TAB
+//! - Filenames containing ":" as they are not supported on Windows
+//!
+//! Only files added to git are checked, as it may be acceptable to have temporary
+//! invalid filenames in the local directory during development.
+
+use std::path::Path;
+use std::process::Command;
+
+pub fn check(root_path: &Path, bad: &mut bool) {
+    let stat_output = Command::new("git")
+        .arg("-C")
+        .arg(root_path)
+        .args(["ls-files", "-z"])
+        .output()
+        .unwrap()
+        .stdout;
+    for filename in stat_output.split(|&b| b == 0) {
+        match str::from_utf8(filename) {
+            Err(_) => tidy_error!(
+                bad,
+                r#"non-UTF8 file names are not supported: "{}""#,
+                String::from_utf8_lossy(filename),
+            ),
+            Ok(name) if name.chars().any(|c| c.is_control()) => tidy_error!(
+                bad,
+                r#"control characters are not supported in file names: "{}""#,
+                String::from_utf8_lossy(filename),
+            ),
+            Ok(name) if name.contains(':') => tidy_error!(
+                bad,
+                r#"":" is not supported in file names because of Windows compatibility: "{name}""#,
+            ),
+            _ => (),
+        }
+    }
+}
diff --git a/src/tools/tidy/src/fluent_period.rs b/src/tools/tidy/src/fluent_period.rs
index 85c1ef6166a..836b5699289 100644
--- a/src/tools/tidy/src/fluent_period.rs
+++ b/src/tools/tidy/src/fluent_period.rs
@@ -33,14 +33,14 @@ fn check_period(filename: &str, contents: &str, bad: &mut bool) {
                 continue;
             }
 
-            if let Some(pat) = &m.value {
-                if let Some(PatternElement::TextElement { value }) = pat.elements.last() {
-                    // We don't care about ellipses.
-                    if value.ends_with(".") && !value.ends_with("...") {
-                        let ll = find_line(contents, value);
-                        let name = m.id.name;
-                        tidy_error!(bad, "{filename}:{ll}: message `{name}` ends in a period");
-                    }
+            if let Some(pat) = &m.value
+                && let Some(PatternElement::TextElement { value }) = pat.elements.last()
+            {
+                // We don't care about ellipses.
+                if value.ends_with(".") && !value.ends_with("...") {
+                    let ll = find_line(contents, value);
+                    let name = m.id.name;
+                    tidy_error!(bad, "{filename}:{ll}: message `{name}` ends in a period");
                 }
             }
 
@@ -50,12 +50,13 @@ fn check_period(filename: &str, contents: &str, bad: &mut bool) {
                     continue;
                 }
 
-                if let Some(PatternElement::TextElement { value }) = attr.value.elements.last() {
-                    if value.ends_with(".") && !value.ends_with("...") {
-                        let ll = find_line(contents, value);
-                        let name = attr.id.name;
-                        tidy_error!(bad, "{filename}:{ll}: attr `{name}` ends in a period");
-                    }
+                if let Some(PatternElement::TextElement { value }) = attr.value.elements.last()
+                    && value.ends_with(".")
+                    && !value.ends_with("...")
+                {
+                    let ll = find_line(contents, value);
+                    let name = attr.id.name;
+                    tidy_error!(bad, "{filename}:{ll}: attr `{name}` ends in a period");
                 }
             }
         }
diff --git a/src/tools/tidy/src/fluent_used.rs b/src/tools/tidy/src/fluent_used.rs
index 12fafd9a7ff..909bf482ddf 100644
--- a/src/tools/tidy/src/fluent_used.rs
+++ b/src/tools/tidy/src/fluent_used.rs
@@ -12,7 +12,7 @@ fn filter_used_messages(
 ) {
     // we don't just check messages never appear in Rust files,
     // because messages can be used as parts of other fluent messages in Fluent files,
-    // so we do checking messages appear only once in all Rust and Fluent files.
+    // so we check messages appear only once in all Rust and Fluent files.
     let matches = static_regex!(r"\w+").find_iter(contents);
     for name in matches {
         if let Some((name, filename)) = msgs_not_appeared_yet.remove_entry(name.as_str()) {
diff --git a/src/tools/tidy/src/issues.txt b/src/tools/tidy/src/issues.txt
index cac4dba2b49..77414bec82d 100644
--- a/src/tools/tidy/src/issues.txt
+++ b/src/tools/tidy/src/issues.txt
@@ -1021,7 +1021,6 @@ ui/foreign/issue-91370-foreign-fn-block-impl.rs
 ui/foreign/issue-99276-same-type-lifetimes.rs
 ui/function-pointer/issue-102289.rs
 ui/functions-closures/closure-expected-type/issue-38714.rs
-ui/generic-associated-types/bugs/issue-100013.rs
 ui/generic-associated-types/bugs/issue-80626.rs
 ui/generic-associated-types/bugs/issue-87735.rs
 ui/generic-associated-types/bugs/issue-87755.rs
@@ -1099,7 +1098,6 @@ ui/generic-associated-types/issue-90729.rs
 ui/generic-associated-types/issue-91139.rs
 ui/generic-associated-types/issue-91883.rs
 ui/generic-associated-types/issue-92033.rs
-ui/generic-associated-types/issue-92096.rs
 ui/generic-associated-types/issue-92280.rs
 ui/generic-associated-types/issue-92954.rs
 ui/generic-associated-types/issue-93141.rs
@@ -2338,7 +2336,6 @@ ui/issues/issue-50415.rs
 ui/issues/issue-50442.rs
 ui/issues/issue-50471.rs
 ui/issues/issue-50518.rs
-ui/issues/issue-50571.rs
 ui/issues/issue-50581.rs
 ui/issues/issue-50582.rs
 ui/issues/issue-50585.rs
diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 77855392b4d..cb875504e1e 100644
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -13,8 +13,9 @@ use termcolor::WriteColor;
 
 macro_rules! static_regex {
     ($re:literal) => {{
-        static RE: ::std::sync::OnceLock<::regex::Regex> = ::std::sync::OnceLock::new();
-        RE.get_or_init(|| ::regex::Regex::new($re).unwrap())
+        static RE: ::std::sync::LazyLock<::regex::Regex> =
+            ::std::sync::LazyLock::new(|| ::regex::Regex::new($re).unwrap());
+        &*RE
     }};
 }
 
@@ -134,7 +135,7 @@ pub fn files_modified(ci_info: &CiInfo, pred: impl Fn(&str) -> bool) -> bool {
         eprintln!("No base commit, assuming all files are modified");
         return true;
     };
-    match crate::git_diff(&base_commit, "--name-status") {
+    match crate::git_diff(base_commit, "--name-status") {
         Some(output) => {
             let modified_files = output.lines().filter_map(|ln| {
                 let (status, name) = ln
@@ -167,6 +168,7 @@ pub mod error_codes;
 pub mod ext_tool_checks;
 pub mod extdeps;
 pub mod features;
+pub mod filenames;
 pub mod fluent_alphabetical;
 pub mod fluent_period;
 mod fluent_used;
diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index a67f7a511b5..0f1116a632e 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -155,6 +155,8 @@ fn main() {
 
         check!(triagebot, &root_path);
 
+        check!(filenames, &root_path);
+
         let collected = {
             drain_handles(&mut handles);
 
diff --git a/src/tools/tidy/src/mir_opt_tests.rs b/src/tools/tidy/src/mir_opt_tests.rs
index 1efe71b1687..6119eb58383 100644
--- a/src/tools/tidy/src/mir_opt_tests.rs
+++ b/src/tools/tidy/src/mir_opt_tests.rs
@@ -55,22 +55,21 @@ fn check_dash_files(path: &Path, bless: bool, bad: &mut bool) {
         .filter(|e| e.file_type().is_file())
     {
         let path = file.path();
-        if path.extension() == Some("rs".as_ref()) {
-            if let Some(name) = path.file_name().and_then(|s| s.to_str()) {
-                if name.contains('-') {
-                    if !bless {
-                        tidy_error!(
-                            bad,
-                            "mir-opt test files should not have dashes in them: {}",
-                            path.display()
-                        );
-                    } else {
-                        let new_name = name.replace('-', "_");
-                        let mut new_path = path.to_owned();
-                        new_path.set_file_name(new_name);
-                        let _ = std::fs::rename(path, new_path);
-                    }
-                }
+        if path.extension() == Some("rs".as_ref())
+            && let Some(name) = path.file_name().and_then(|s| s.to_str())
+            && name.contains('-')
+        {
+            if !bless {
+                tidy_error!(
+                    bad,
+                    "mir-opt test files should not have dashes in them: {}",
+                    path.display()
+                );
+            } else {
+                let new_name = name.replace('-', "_");
+                let mut new_path = path.to_owned();
+                new_path.set_file_name(new_name);
+                let _ = std::fs::rename(path, new_path);
             }
         }
     }
diff --git a/src/tools/tidy/src/rustdoc_templates.rs b/src/tools/tidy/src/rustdoc_templates.rs
index dca3e8d9d25..597290a6a9a 100644
--- a/src/tools/tidy/src/rustdoc_templates.rs
+++ b/src/tools/tidy/src/rustdoc_templates.rs
@@ -26,7 +26,7 @@ pub fn check(librustdoc_path: &Path, bad: &mut bool) {
                         None
                     // Then we check if this a comment tag.
                     } else if *tag != "{#" {
-                        return Some(false);
+                        Some(false)
                     // And finally we check if the comment is empty (ie, only there to strip
                     // extra whitespace characters).
                     } else if let Some(start_pos) = line.rfind(tag) {
diff --git a/src/tools/tidy/src/style.rs b/src/tools/tidy/src/style.rs
index 8dde4618ce5..35ed61eacc7 100644
--- a/src/tools/tidy/src/style.rs
+++ b/src/tools/tidy/src/style.rs
@@ -417,10 +417,10 @@ pub fn check(path: &Path, bad: &mut bool) {
             return;
         }
         // Shell completions are automatically generated
-        if let Some(p) = file.parent() {
-            if p.ends_with(Path::new("src/etc/completions")) {
-                return;
-            }
+        if let Some(p) = file.parent()
+            && p.ends_with(Path::new("src/etc/completions"))
+        {
+            return;
         }
         let [
             mut skip_cr,
@@ -604,25 +604,25 @@ pub fn check(path: &Path, bad: &mut bool) {
                         backtick_count += comment_text.chars().filter(|ch| *ch == '`').count();
                     }
                     comment_block = Some((start_line, backtick_count));
-                } else if let Some((start_line, backtick_count)) = comment_block.take() {
-                    if backtick_count % 2 == 1 {
-                        let mut err = |msg: &str| {
-                            tidy_error!(bad, "{}:{start_line}: {msg}", file.display());
-                        };
-                        let block_len = (i + 1) - start_line;
-                        if block_len == 1 {
-                            suppressible_tidy_err!(
-                                err,
-                                skip_odd_backticks,
-                                "comment with odd number of backticks"
-                            );
-                        } else {
-                            suppressible_tidy_err!(
-                                err,
-                                skip_odd_backticks,
-                                "{block_len}-line comment block with odd number of backticks"
-                            );
-                        }
+                } else if let Some((start_line, backtick_count)) = comment_block.take()
+                    && backtick_count % 2 == 1
+                {
+                    let mut err = |msg: &str| {
+                        tidy_error!(bad, "{}:{start_line}: {msg}", file.display());
+                    };
+                    let block_len = (i + 1) - start_line;
+                    if block_len == 1 {
+                        suppressible_tidy_err!(
+                            err,
+                            skip_odd_backticks,
+                            "comment with odd number of backticks"
+                        );
+                    } else {
+                        suppressible_tidy_err!(
+                            err,
+                            skip_odd_backticks,
+                            "{block_len}-line comment block with odd number of backticks"
+                        );
                     }
                 }
             }
diff --git a/src/tools/tidy/src/target_specific_tests.rs b/src/tools/tidy/src/target_specific_tests.rs
index 1a6fd3eaf2d..f4a6783abb6 100644
--- a/src/tools/tidy/src/target_specific_tests.rs
+++ b/src/tools/tidy/src/target_specific_tests.rs
@@ -30,17 +30,17 @@ pub fn check(tests_path: &Path, bad: &mut bool) {
                         comp_vec.push(component);
                     }
                 }
-            } else if let Some(compile_flags) = directive.strip_prefix(COMPILE_FLAGS_HEADER) {
-                if let Some((_, v)) = compile_flags.split_once("--target") {
-                    let v = v.trim_start_matches([' ', '=']);
-                    let v = if v == "{{target}}" { Some((v, v)) } else { v.split_once("-") };
-                    if let Some((arch, _)) = v {
-                        let info = header_map.entry(revision).or_insert(RevisionInfo::default());
-                        info.target_arch.replace(arch);
-                    } else {
-                        eprintln!("{file}: seems to have a malformed --target value");
-                        *bad = true;
-                    }
+            } else if let Some(compile_flags) = directive.strip_prefix(COMPILE_FLAGS_HEADER)
+                && let Some((_, v)) = compile_flags.split_once("--target")
+            {
+                let v = v.trim_start_matches([' ', '=']);
+                let v = if v == "{{target}}" { Some((v, v)) } else { v.split_once("-") };
+                if let Some((arch, _)) = v {
+                    let info = header_map.entry(revision).or_insert(RevisionInfo::default());
+                    info.target_arch.replace(arch);
+                } else {
+                    eprintln!("{file}: seems to have a malformed --target value");
+                    *bad = true;
                 }
             }
         });
diff --git a/src/tools/tidy/src/ui_tests.rs b/src/tools/tidy/src/ui_tests.rs
index b1ace74e5bd..b9d22ece597 100644
--- a/src/tools/tidy/src/ui_tests.rs
+++ b/src/tools/tidy/src/ui_tests.rs
@@ -17,7 +17,7 @@ use ignore::Walk;
 const ENTRY_LIMIT: u32 = 901;
 // FIXME: The following limits should be reduced eventually.
 
-const ISSUES_ENTRY_LIMIT: u32 = 1619;
+const ISSUES_ENTRY_LIMIT: u32 = 1616;
 
 const EXPECTED_TEST_FILE_EXTENSIONS: &[&str] = &[
     "rs",     // test source files
@@ -161,31 +161,30 @@ pub fn check(root_path: &Path, bless: bool, bad: &mut bool) {
                     tidy_error!(bad, "Stray file with UI testing output: {:?}", file_path);
                 }
 
-                if let Ok(metadata) = fs::metadata(file_path) {
-                    if metadata.len() == 0 {
-                        tidy_error!(bad, "Empty file with UI testing output: {:?}", file_path);
-                    }
+                if let Ok(metadata) = fs::metadata(file_path)
+                    && metadata.len() == 0
+                {
+                    tidy_error!(bad, "Empty file with UI testing output: {:?}", file_path);
                 }
             }
 
-            if ext == "rs" {
-                if let Some(test_name) = static_regex!(r"^issues?[-_]?(\d{3,})").captures(testname)
-                {
-                    // these paths are always relative to the passed `path` and always UTF8
-                    let stripped_path = file_path
-                        .strip_prefix(path)
-                        .unwrap()
-                        .to_str()
-                        .unwrap()
-                        .replace(std::path::MAIN_SEPARATOR_STR, "/");
-
-                    if !remaining_issue_names.remove(stripped_path.as_str()) {
-                        tidy_error!(
-                            bad,
-                            "file `tests/{stripped_path}` must begin with a descriptive name, consider `{{reason}}-issue-{issue_n}.rs`",
-                            issue_n = &test_name[1],
-                        );
-                    }
+            if ext == "rs"
+                && let Some(test_name) = static_regex!(r"^issues?[-_]?(\d{3,})").captures(testname)
+            {
+                // these paths are always relative to the passed `path` and always UTF8
+                let stripped_path = file_path
+                    .strip_prefix(path)
+                    .unwrap()
+                    .to_str()
+                    .unwrap()
+                    .replace(std::path::MAIN_SEPARATOR_STR, "/");
+
+                if !remaining_issue_names.remove(stripped_path.as_str()) {
+                    tidy_error!(
+                        bad,
+                        "file `tests/{stripped_path}` must begin with a descriptive name, consider `{{reason}}-issue-{issue_n}.rs`",
+                        issue_n = &test_name[1],
+                    );
                 }
             }
         }
diff --git a/src/tools/tidy/src/x_version.rs b/src/tools/tidy/src/x_version.rs
index 6a5e9eca813..9f7f43c4000 100644
--- a/src/tools/tidy/src/x_version.rs
+++ b/src/tools/tidy/src/x_version.rs
@@ -25,12 +25,12 @@ pub fn check(root: &Path, cargo: &Path, bad: &mut bool) {
                 if let Some(version) = iter.next() {
                     // Check this is the rust-lang/rust x tool installation since it should be
                     // installed at a path containing `src/tools/x`.
-                    if let Some(path) = iter.next() {
-                        if path.contains("src/tools/x") {
-                            let version = version.strip_prefix("v").unwrap();
-                            installed = Some(Version::parse(version).unwrap());
-                            break;
-                        }
+                    if let Some(path) = iter.next()
+                        && path.contains("src/tools/x")
+                    {
+                        let version = version.strip_prefix("v").unwrap();
+                        installed = Some(Version::parse(version).unwrap());
+                        break;
                     };
                 }
             } else {
diff --git a/src/tools/unicode-table-generator/Cargo.toml b/src/tools/unicode-table-generator/Cargo.toml
index f8a500922d0..3ca6e9e316f 100644
--- a/src/tools/unicode-table-generator/Cargo.toml
+++ b/src/tools/unicode-table-generator/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "unicode-table-generator"
 version = "0.1.0"
-edition = "2021"
+edition = "2024"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
diff --git a/src/tools/unicode-table-generator/src/cascading_map.rs b/src/tools/unicode-table-generator/src/cascading_map.rs
index 1eb35e819c0..78a7bba3208 100644
--- a/src/tools/unicode-table-generator/src/cascading_map.rs
+++ b/src/tools/unicode-table-generator/src/cascading_map.rs
@@ -21,7 +21,7 @@ impl RawEmitter {
 
         let points = ranges
             .iter()
-            .flat_map(|r| (r.start..r.end).into_iter().collect::<Vec<u32>>())
+            .flat_map(|r| (r.start..r.end).collect::<Vec<u32>>())
             .collect::<Vec<u32>>();
 
         println!("there are {} points", points.len());
@@ -32,21 +32,20 @@ impl RawEmitter {
             // assert that there is no whitespace over the 0x3000 range.
             assert!(point <= 0x3000, "the highest unicode whitespace value has changed");
             let high_bytes = point as usize >> 8;
-            let codepoints = codepoints_by_high_bytes.entry(high_bytes).or_insert_with(Vec::new);
+            let codepoints = codepoints_by_high_bytes.entry(high_bytes).or_default();
             codepoints.push(point);
         }
 
         let mut bit_for_high_byte = 1u8;
         let mut arms = Vec::<String>::new();
 
-        let mut high_bytes: Vec<usize> =
-            codepoints_by_high_bytes.keys().map(|k| k.clone()).collect();
+        let mut high_bytes: Vec<usize> = codepoints_by_high_bytes.keys().copied().collect();
         high_bytes.sort();
         for high_byte in high_bytes {
             let codepoints = codepoints_by_high_bytes.get_mut(&high_byte).unwrap();
             if codepoints.len() == 1 {
                 let ch = codepoints.pop().unwrap();
-                arms.push(format!("{} => c as u32 == {:#04x}", high_byte, ch));
+                arms.push(format!("{high_byte} => c as u32 == {ch:#04x}"));
                 continue;
             }
             // more than 1 codepoint in this arm
@@ -54,8 +53,7 @@ impl RawEmitter {
                 map[(*codepoint & 0xff) as usize] |= bit_for_high_byte;
             }
             arms.push(format!(
-                "{} => WHITESPACE_MAP[c as usize & 0xff] & {} != 0",
-                high_byte, bit_for_high_byte
+                "{high_byte} => WHITESPACE_MAP[c as usize & 0xff] & {bit_for_high_byte} != 0"
             ));
             bit_for_high_byte <<= 1;
         }
@@ -68,7 +66,7 @@ impl RawEmitter {
         writeln!(&mut self.file, "pub const fn lookup(c: char) -> bool {{").unwrap();
         writeln!(&mut self.file, "    match c as u32 >> 8 {{").unwrap();
         for arm in arms {
-            writeln!(&mut self.file, "        {},", arm).unwrap();
+            writeln!(&mut self.file, "        {arm},").unwrap();
         }
         writeln!(&mut self.file, "        _ => false,").unwrap();
         writeln!(&mut self.file, "    }}").unwrap();
diff --git a/src/tools/unicode-table-generator/src/case_mapping.rs b/src/tools/unicode-table-generator/src/case_mapping.rs
index 00241b7ee0e..9c6454492e7 100644
--- a/src/tools/unicode-table-generator/src/case_mapping.rs
+++ b/src/tools/unicode-table-generator/src/case_mapping.rs
@@ -9,7 +9,7 @@ const INDEX_MASK: u32 = 1 << 22;
 pub(crate) fn generate_case_mapping(data: &UnicodeData) -> String {
     let mut file = String::new();
 
-    write!(file, "const INDEX_MASK: u32 = 0x{:x};", INDEX_MASK).unwrap();
+    write!(file, "const INDEX_MASK: u32 = 0x{INDEX_MASK:x};").unwrap();
     file.push_str("\n\n");
     file.push_str(HEADER.trim_start());
     file.push('\n');
diff --git a/src/tools/unicode-table-generator/src/main.rs b/src/tools/unicode-table-generator/src/main.rs
index 415db2c4dbc..6cdb82a87bd 100644
--- a/src/tools/unicode-table-generator/src/main.rs
+++ b/src/tools/unicode-table-generator/src/main.rs
@@ -160,15 +160,15 @@ fn load_data() -> UnicodeData {
                 .push(Codepoints::Single(row.codepoint));
         }
 
-        if let Some(mapped) = row.simple_lowercase_mapping {
-            if mapped != row.codepoint {
-                to_lower.insert(row.codepoint.value(), (mapped.value(), 0, 0));
-            }
+        if let Some(mapped) = row.simple_lowercase_mapping
+            && mapped != row.codepoint
+        {
+            to_lower.insert(row.codepoint.value(), (mapped.value(), 0, 0));
         }
-        if let Some(mapped) = row.simple_uppercase_mapping {
-            if mapped != row.codepoint {
-                to_upper.insert(row.codepoint.value(), (mapped.value(), 0, 0));
-            }
+        if let Some(mapped) = row.simple_uppercase_mapping
+            && mapped != row.codepoint
+        {
+            to_upper.insert(row.codepoint.value(), (mapped.value(), 0, 0));
         }
     }
 
@@ -196,12 +196,12 @@ fn load_data() -> UnicodeData {
                     .flat_map(|codepoints| match codepoints {
                         Codepoints::Single(c) => c
                             .scalar()
-                            .map(|ch| (ch as u32..ch as u32 + 1))
+                            .map(|ch| ch as u32..ch as u32 + 1)
                             .into_iter()
                             .collect::<Vec<_>>(),
                         Codepoints::Range(c) => c
                             .into_iter()
-                            .flat_map(|c| c.scalar().map(|ch| (ch as u32..ch as u32 + 1)))
+                            .flat_map(|c| c.scalar().map(|ch| ch as u32..ch as u32 + 1))
                             .collect::<Vec<_>>(),
                     })
                     .collect::<Vec<Range<u32>>>(),
@@ -236,7 +236,7 @@ fn main() {
     let ranges_by_property = &unicode_data.ranges;
 
     if let Some(path) = test_path {
-        std::fs::write(&path, generate_tests(&write_location, &ranges_by_property)).unwrap();
+        std::fs::write(&path, generate_tests(&write_location, ranges_by_property)).unwrap();
     }
 
     let mut total_bytes = 0;
@@ -246,9 +246,9 @@ fn main() {
 
         let mut emitter = RawEmitter::new();
         if property == &"White_Space" {
-            emit_whitespace(&mut emitter, &ranges);
+            emit_whitespace(&mut emitter, ranges);
         } else {
-            emit_codepoints(&mut emitter, &ranges);
+            emit_codepoints(&mut emitter, ranges);
         }
 
         modules.push((property.to_lowercase().to_string(), emitter.file));
@@ -288,7 +288,7 @@ fn main() {
         for line in contents.lines() {
             if !line.trim().is_empty() {
                 table_file.push_str("    ");
-                table_file.push_str(&line);
+                table_file.push_str(line);
             }
             table_file.push('\n');
         }
@@ -312,7 +312,7 @@ fn version() -> String {
     let start = readme.find(prefix).unwrap() + prefix.len();
     let end = readme.find(" of the Unicode Standard.").unwrap();
     let version =
-        readme[start..end].split('.').map(|v| v.parse::<u32>().expect(&v)).collect::<Vec<_>>();
+        readme[start..end].split('.').map(|v| v.parse::<u32>().expect(v)).collect::<Vec<_>>();
     let [major, minor, micro] = [version[0], version[1], version[2]];
 
     out.push_str(&format!("({major}, {minor}, {micro});\n"));
@@ -320,7 +320,7 @@ fn version() -> String {
 }
 
 fn fmt_list<V: std::fmt::Debug>(values: impl IntoIterator<Item = V>) -> String {
-    let pieces = values.into_iter().map(|b| format!("{:?}, ", b)).collect::<Vec<_>>();
+    let pieces = values.into_iter().map(|b| format!("{b:?}, ")).collect::<Vec<_>>();
     let mut out = String::new();
     let mut line = String::from("\n    ");
     for piece in pieces {
@@ -348,7 +348,7 @@ fn generate_tests(data_path: &str, ranges: &[(&str, Vec<Range<u32>>)]) -> String
     s.push_str("\nfn main() {\n");
 
     for (property, ranges) in ranges {
-        s.push_str(&format!(r#"    println!("Testing {}");"#, property));
+        s.push_str(&format!(r#"    println!("Testing {property}");"#));
         s.push('\n');
         s.push_str(&format!("    {}_true();\n", property.to_lowercase()));
         s.push_str(&format!("    {}_false();\n", property.to_lowercase()));
@@ -373,7 +373,7 @@ fn generate_tests(data_path: &str, ranges: &[(&str, Vec<Range<u32>>)]) -> String
         s.push_str("    }\n\n");
     }
 
-    s.push_str("}");
+    s.push('}');
     s
 }
 
@@ -388,7 +388,7 @@ fn generate_asserts(s: &mut String, property: &str, points: &[u32], truthy: bool
                 range.start,
             ));
         } else {
-            s.push_str(&format!("        for chn in {:?}u32 {{\n", range));
+            s.push_str(&format!("        for chn in {range:?}u32 {{\n"));
             s.push_str(&format!(
                 "            assert!({}unicode_data::{}::lookup(std::char::from_u32(chn).unwrap()), \"{{:?}}\", chn);\n",
                 if truthy { "" } else { "!" },
@@ -439,7 +439,7 @@ fn merge_ranges(ranges: &mut Vec<Range<u32>>) {
     let mut last_end = None;
     for range in ranges {
         if let Some(last) = last_end {
-            assert!(range.start > last, "{:?}", range);
+            assert!(range.start > last, "{range:?}");
         }
         last_end = Some(range.end);
     }
diff --git a/src/tools/unicode-table-generator/src/raw_emitter.rs b/src/tools/unicode-table-generator/src/raw_emitter.rs
index ee94d3c93a6..e9e0efc4594 100644
--- a/src/tools/unicode-table-generator/src/raw_emitter.rs
+++ b/src/tools/unicode-table-generator/src/raw_emitter.rs
@@ -156,10 +156,10 @@ pub fn emit_codepoints(emitter: &mut RawEmitter, ranges: &[Range<u32>]) {
     emitter.blank_line();
 
     let mut bitset = emitter.clone();
-    let bitset_ok = bitset.emit_bitset(&ranges).is_ok();
+    let bitset_ok = bitset.emit_bitset(ranges).is_ok();
 
     let mut skiplist = emitter.clone();
-    skiplist.emit_skiplist(&ranges);
+    skiplist.emit_skiplist(ranges);
 
     if bitset_ok && bitset.bytes_used <= skiplist.bytes_used {
         *emitter = bitset;
@@ -174,7 +174,7 @@ pub fn emit_whitespace(emitter: &mut RawEmitter, ranges: &[Range<u32>]) {
     emitter.blank_line();
 
     let mut cascading = emitter.clone();
-    cascading.emit_cascading_map(&ranges);
+    cascading.emit_cascading_map(ranges);
     *emitter = cascading;
     emitter.desc = String::from("cascading");
 }
@@ -272,7 +272,7 @@ impl Canonicalized {
         // for canonical when possible.
         while let Some((&to, _)) = mappings
             .iter()
-            .find(|(&to, _)| to == 0)
+            .find(|&(&to, _)| to == 0)
             .or_else(|| mappings.iter().max_by_key(|m| m.1.len()))
         {
             // Get the mapping with the most entries. Currently, no mapping can
@@ -311,10 +311,9 @@ impl Canonicalized {
                     }
                 }
             }
-            assert!(
-                unique_mapping
-                    .insert(to, UniqueMapping::Canonical(canonical_words.len()))
-                    .is_none()
+            assert_eq!(
+                unique_mapping.insert(to, UniqueMapping::Canonical(canonical_words.len())),
+                None
             );
             canonical_words.push(to);
 
@@ -340,14 +339,10 @@ impl Canonicalized {
         // We'll probably always have some slack though so this loop will still
         // be needed.
         for &w in unique_words {
-            if !unique_mapping.contains_key(&w) {
-                assert!(
-                    unique_mapping
-                        .insert(w, UniqueMapping::Canonical(canonical_words.len()))
-                        .is_none()
-                );
+            unique_mapping.entry(w).or_insert_with(|| {
                 canonical_words.push(w);
-            }
+                UniqueMapping::Canonical(canonical_words.len())
+            });
         }
         assert_eq!(canonicalized_words.len() + canonical_words.len(), unique_words.len());
         assert_eq!(unique_mapping.len(), unique_words.len());