Auto merge of #94480 - bjorn3:no_build_helper, r=Mark-Simulacrum

Remove build_helper

The majority of the code is only used by either rustbuild or
rustc_llvm's build script. Rust_build is compiled once for rustbuild and
once for every stage. This means that the majority of the code in this
crate is needlessly compiled multiple times. By moving only the code
actually used by the respective crates to rustbuild and rustc_llvm's
build script, this needless duplicate compilation is avoided.

27 files changed, 236 insertions, 272 deletions

diff --git a/Cargo.lock b/Cargo.lock
index d7d221ee66f..2ee9a872d3e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -214,7 +214,6 @@ dependencies = [
 name = "bootstrap"
 version = "0.0.0"
 dependencies = [
- "build_helper",
  "cc",
  "cmake",
  "filetime",
@@ -257,10 +256,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "build_helper"
-version = "0.1.0"
-
-[[package]]
 name = "bump-stage0"
 version = "0.1.0"
 dependencies = [
@@ -3891,7 +3886,6 @@ dependencies = [
 name = "rustc_llvm"
 version = "0.0.0"
 dependencies = [
- "build_helper",
  "cc",
  "libc",
 ]
diff --git a/compiler/rustc_llvm/Cargo.toml b/compiler/rustc_llvm/Cargo.toml
index d8dfcc84e68..34556df3c6d 100644
--- a/compiler/rustc_llvm/Cargo.toml
+++ b/compiler/rustc_llvm/Cargo.toml
@@ -11,5 +11,4 @@ emscripten = []
 libc = "0.2.73"
 
 [build-dependencies]
-build_helper = { path = "../../src/build_helper" }
 cc = "1.0.69"
diff --git a/compiler/rustc_llvm/build.rs b/compiler/rustc_llvm/build.rs
index 3b6808d693f..ac758c15cca 100644
--- a/compiler/rustc_llvm/build.rs
+++ b/compiler/rustc_llvm/build.rs
@@ -1,8 +1,8 @@
 use std::env;
+use std::ffi::{OsStr, OsString};
+use std::fmt::Display;
 use std::path::{Path, PathBuf};
-use std::process::Command;
-
-use build_helper::{output, tracked_env_var_os};
+use std::process::{Command, Stdio};
 
 fn detect_llvm_link() -> (&'static str, &'static str) {
     // Force the link mode we want, preferring static by default, but
@@ -14,13 +14,74 @@ fn detect_llvm_link() -> (&'static str, &'static str) {
     }
 }
 
+// Because Cargo adds the compiler's dylib path to our library search path, llvm-config may
+// break: the dylib path for the compiler, as of this writing, contains a copy of the LLVM
+// shared library, which means that when our freshly built llvm-config goes to load it's
+// associated LLVM, it actually loads the compiler's LLVM. In particular when building the first
+// compiler (i.e., in stage 0) that's a problem, as the compiler's LLVM is likely different from
+// the one we want to use. As such, we restore the environment to what bootstrap saw. This isn't
+// perfect -- we might actually want to see something from Cargo's added library paths -- but
+// for now it works.
+fn restore_library_path() {
+    let key = tracked_env_var_os("REAL_LIBRARY_PATH_VAR").expect("REAL_LIBRARY_PATH_VAR");
+    if let Some(env) = tracked_env_var_os("REAL_LIBRARY_PATH") {
+        env::set_var(&key, &env);
+    } else {
+        env::remove_var(&key);
+    }
+}
+
+/// Reads an environment variable and adds it to dependencies.
+/// Supposed to be used for all variables except those set for build scripts by cargo
+/// <https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts>
+fn tracked_env_var_os<K: AsRef<OsStr> + Display>(key: K) -> Option<OsString> {
+    println!("cargo:rerun-if-env-changed={}", key);
+    env::var_os(key)
+}
+
+fn rerun_if_changed_anything_in_dir(dir: &Path) {
+    let mut stack = dir
+        .read_dir()
+        .unwrap()
+        .map(|e| e.unwrap())
+        .filter(|e| &*e.file_name() != ".git")
+        .collect::<Vec<_>>();
+    while let Some(entry) = stack.pop() {
+        let path = entry.path();
+        if entry.file_type().unwrap().is_dir() {
+            stack.extend(path.read_dir().unwrap().map(|e| e.unwrap()));
+        } else {
+            println!("cargo:rerun-if-changed={}", path.display());
+        }
+    }
+}
+
+#[track_caller]
+fn output(cmd: &mut Command) -> String {
+    let output = match cmd.stderr(Stdio::inherit()).output() {
+        Ok(status) => status,
+        Err(e) => {
+            println!("\n\nfailed to execute command: {:?}\nerror: {}\n\n", cmd, e);
+            std::process::exit(1);
+        }
+    };
+    if !output.status.success() {
+        panic!(
+            "command did not execute successfully: {:?}\n\
+             expected success, got: {}",
+            cmd, output.status
+        );
+    }
+    String::from_utf8(output.stdout).unwrap()
+}
+
 fn main() {
     if tracked_env_var_os("RUST_CHECK").is_some() {
         // If we're just running `check`, there's no need for LLVM to be built.
         return;
     }
 
-    build_helper::restore_library_path();
+    restore_library_path();
 
     let target = env::var("TARGET").expect("TARGET was not set");
     let llvm_config =
@@ -160,7 +221,7 @@ fn main() {
         cfg.debug(false);
     }
 
-    build_helper::rerun_if_changed_anything_in_dir(Path::new("llvm-wrapper"));
+    rerun_if_changed_anything_in_dir(Path::new("llvm-wrapper"));
     cfg.file("llvm-wrapper/PassWrapper.cpp")
         .file("llvm-wrapper/RustWrapper.cpp")
         .file("llvm-wrapper/ArchiveWrapper.cpp")
diff --git a/src/bootstrap/Cargo.toml b/src/bootstrap/Cargo.toml
index 02efc08cc79..fe9d6a727ed 100644
--- a/src/bootstrap/Cargo.toml
+++ b/src/bootstrap/Cargo.toml
@@ -34,7 +34,6 @@ path = "bin/llvm-config-wrapper.rs"
 test = false
 
 [dependencies]
-build_helper = { path = "../build_helper" }
 cmake = "0.1.38"
 filetime = "0.2"
 getopts = "0.2.19"
diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 00aebc21f58..fc55c8626d9 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -11,8 +11,6 @@ use std::path::{Component, Path, PathBuf};
 use std::process::Command;
 use std::time::{Duration, Instant};
 
-use build_helper::{output, t};
-
 use crate::cache::{Cache, Interned, INTERNER};
 use crate::check;
 use crate::compile;
@@ -25,7 +23,7 @@ use crate::native;
 use crate::run;
 use crate::test;
 use crate::tool::{self, SourceType};
-use crate::util::{self, add_dylib_path, add_link_lib_path, exe, libdir};
+use crate::util::{self, add_dylib_path, add_link_lib_path, exe, libdir, output, t};
 use crate::EXTRA_CHECK_CFGS;
 use crate::{Build, CLang, DocTests, GitRepo, Mode};
 
diff --git a/src/bootstrap/cc_detect.rs b/src/bootstrap/cc_detect.rs
index 8c47f625d73..7ce44687611 100644
--- a/src/bootstrap/cc_detect.rs
+++ b/src/bootstrap/cc_detect.rs
@@ -26,9 +26,8 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::{env, iter};
 
-use build_helper::output;
-
 use crate::config::{Target, TargetSelection};
+use crate::util::output;
 use crate::{Build, CLang, GitRepo};
 
 // The `cc` crate doesn't provide a way to obtain a path to the detected archiver,
diff --git a/src/bootstrap/channel.rs b/src/bootstrap/channel.rs
index 6478578c3c4..1932a0017ee 100644
--- a/src/bootstrap/channel.rs
+++ b/src/bootstrap/channel.rs
@@ -8,8 +8,7 @@
 use std::path::Path;
 use std::process::Command;
 
-use build_helper::output;
-
+use crate::util::output;
 use crate::Build;
 
 pub enum GitInfo {
diff --git a/src/bootstrap/clean.rs b/src/bootstrap/clean.rs
index 3b73dc1c7df..069f3d6acf1 100644
--- a/src/bootstrap/clean.rs
+++ b/src/bootstrap/clean.rs
@@ -9,8 +9,7 @@ use std::fs;
 use std::io::{self, ErrorKind};
 use std::path::Path;
 
-use build_helper::t;
-
+use crate::util::t;
 use crate::Build;
 
 pub fn clean(build: &Build, all: bool) {
diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 99717780346..9cfd9f92aa7 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -16,7 +16,6 @@ use std::path::{Path, PathBuf};
 use std::process::{exit, Command, Stdio};
 use std::str;
 
-use build_helper::{output, t, up_to_date};
 use serde::Deserialize;
 
 use crate::builder::Cargo;
@@ -26,7 +25,7 @@ use crate::config::{LlvmLibunwind, TargetSelection};
 use crate::dist;
 use crate::native;
 use crate::tool::SourceType;
-use crate::util::{exe, is_debug_info, is_dylib, symlink_dir};
+use crate::util::{exe, is_debug_info, is_dylib, output, symlink_dir, t, up_to_date};
 use crate::LLVM_TOOLS;
 use crate::{CLang, Compiler, DependencyType, GitRepo, Mode};
 
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 997e811e214..b17b94f2893 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -17,8 +17,7 @@ use crate::cache::{Interned, INTERNER};
 use crate::channel::GitInfo;
 pub use crate::flags::Subcommand;
 use crate::flags::{Color, Flags};
-use crate::util::exe;
-use build_helper::t;
+use crate::util::{exe, t};
 use serde::Deserialize;
 
 macro_rules! check_ci_llvm {
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 8693e85e474..5f92cc2ca6f 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -14,15 +14,13 @@ use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
-use build_helper::{output, t};
-
 use crate::builder::{Builder, Kind, RunConfig, ShouldRun, Step};
 use crate::cache::{Interned, INTERNER};
 use crate::compile;
 use crate::config::TargetSelection;
 use crate::tarball::{GeneratedTarball, OverlayKind, Tarball};
 use crate::tool::{self, Tool};
-use crate::util::{exe, is_dylib, timeit};
+use crate::util::{exe, is_dylib, output, t, timeit};
 use crate::{Compiler, DependencyType, Mode, LLVM_TOOLS};
 
 pub fn pkgname(builder: &Builder<'_>, component: &str) -> String {
@@ -635,14 +633,6 @@ impl Step for RustcDev {
             &[],
             &tarball.image_dir().join("lib/rustlib/rustc-src/rust"),
         );
-        // This particular crate is used as a build dependency of the above.
-        copy_src_dirs(
-            builder,
-            &builder.src,
-            &["src/build_helper"],
-            &[],
-            &tarball.image_dir().join("lib/rustlib/rustc-src/rust"),
-        );
         for file in src_files {
             tarball.add_file(builder.src.join(file), "lib/rustlib/rustc-src/rust", 0o644);
         }
diff --git a/src/bootstrap/doc.rs b/src/bootstrap/doc.rs
index 23b5ddcd47a..be55871b56a 100644
--- a/src/bootstrap/doc.rs
+++ b/src/bootstrap/doc.rs
@@ -12,15 +12,13 @@ use std::fs;
 use std::io;
 use std::path::{Path, PathBuf};
 
-use crate::Mode;
-use build_helper::{t, up_to_date};
-
 use crate::builder::{Builder, Compiler, Kind, RunConfig, ShouldRun, Step};
 use crate::cache::{Interned, INTERNER};
 use crate::compile;
 use crate::config::{Config, TargetSelection};
 use crate::tool::{self, prepare_tool_cargo, SourceType, Tool};
-use crate::util::symlink_dir;
+use crate::util::{symlink_dir, t, up_to_date};
+use crate::Mode;
 
 macro_rules! submodule_helper {
     ($path:expr, submodule) => {
diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index 74528f2752f..e34b40a93ff 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -7,12 +7,12 @@ use std::env;
 use std::path::PathBuf;
 use std::process;
 
-use build_helper::t;
 use getopts::Options;
 
 use crate::builder::Builder;
 use crate::config::{Config, TargetSelection};
 use crate::setup::Profile;
+use crate::util::t;
 use crate::{Build, DocTests};
 
 pub enum Color {
diff --git a/src/bootstrap/format.rs b/src/bootstrap/format.rs
index 530cc829320..10b846e6db2 100644
--- a/src/bootstrap/format.rs
+++ b/src/bootstrap/format.rs
@@ -1,7 +1,7 @@
 //! Runs rustfmt on the repository.
 
+use crate::util::{output, t};
 use crate::Build;
-use build_helper::{output, t};
 use ignore::WalkBuilder;
 use std::collections::VecDeque;
 use std::path::{Path, PathBuf};
diff --git a/src/bootstrap/install.rs b/src/bootstrap/install.rs
index 06acf1a9a00..27b9196d986 100644
--- a/src/bootstrap/install.rs
+++ b/src/bootstrap/install.rs
@@ -8,7 +8,7 @@ use std::fs;
 use std::path::{Component, PathBuf};
 use std::process::Command;
 
-use build_helper::t;
+use crate::util::t;
 
 use crate::dist::{self, sanitize_sh};
 use crate::tarball::GeneratedTarball;
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 4089a63f881..ccc8516a89a 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -116,12 +116,13 @@ use std::os::unix::fs::symlink as symlink_file;
 #[cfg(windows)]
 use std::os::windows::fs::symlink_file;
 
-use build_helper::{mtime, output, run, run_suppressed, t, try_run, try_run_suppressed};
 use filetime::FileTime;
 
 use crate::builder::Kind;
 use crate::config::{LlvmLibunwind, TargetSelection};
-use crate::util::{exe, libdir, CiEnv};
+use crate::util::{
+    exe, libdir, mtime, output, run, run_suppressed, t, try_run, try_run_suppressed, CiEnv,
+};
 
 mod builder;
 mod cache;
@@ -1301,13 +1302,10 @@ impl Build {
                 }
                 // Don't include optional deps if their features are not
                 // enabled. Ideally this would be computed from `cargo
-                // metadata --features …`, but that is somewhat slow. Just
-                // skip `build_helper` since there aren't any operations we
-                // want to perform on it. In the future, we may want to
-                // consider just filtering all build and dev dependencies in
-                // metadata::build.
+                // metadata --features …`, but that is somewhat slow. In
+                // the future, we may want to consider just filtering all
+                // build and dev dependencies in metadata::build.
                 if visited.insert(dep)
-                    && dep != "build_helper"
                     && (dep != "profiler_builtins"
                         || target
                             .map(|t| self.config.profiler_enabled(t))
diff --git a/src/bootstrap/metadata.rs b/src/bootstrap/metadata.rs
index 65e229697dc..59dc50be47f 100644
--- a/src/bootstrap/metadata.rs
+++ b/src/bootstrap/metadata.rs
@@ -1,10 +1,10 @@
 use std::path::PathBuf;
 use std::process::Command;
 
-use build_helper::output;
 use serde::Deserialize;
 
 use crate::cache::INTERNER;
+use crate::util::output;
 use crate::{Build, Crate};
 
 #[derive(Deserialize)]
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index a751a6e3ece..d27ad9644b5 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -16,13 +16,10 @@ use std::io;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
-use build_helper::{output, t};
-
 use crate::builder::{Builder, RunConfig, ShouldRun, Step};
 use crate::config::TargetSelection;
-use crate::util::{self, exe};
+use crate::util::{self, exe, output, t, up_to_date};
 use crate::{CLang, GitRepo};
-use build_helper::up_to_date;
 
 pub struct Meta {
     stamp: HashStamp,
diff --git a/src/bootstrap/run.rs b/src/bootstrap/run.rs
index 11b393857e7..25abe7a72fd 100644
--- a/src/bootstrap/run.rs
+++ b/src/bootstrap/run.rs
@@ -1,7 +1,7 @@
 use crate::builder::{Builder, RunConfig, ShouldRun, Step};
 use crate::dist::distdir;
 use crate::tool::Tool;
-use build_helper::output;
+use crate::util::output;
 use std::process::Command;
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index d7db2cef24f..8c2899c1ac0 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -15,10 +15,9 @@ use std::fs;
 use std::path::PathBuf;
 use std::process::Command;
 
-use build_helper::output;
-
 use crate::cache::INTERNER;
 use crate::config::Target;
+use crate::util::output;
 use crate::Build;
 
 pub struct Finder {
diff --git a/src/bootstrap/tarball.rs b/src/bootstrap/tarball.rs
index 9ff5c2327e0..c743c5188e7 100644
--- a/src/bootstrap/tarball.rs
+++ b/src/bootstrap/tarball.rs
@@ -3,9 +3,8 @@ use std::{
     process::Command,
 };
 
-use build_helper::t;
-
 use crate::builder::Builder;
+use crate::util::t;
 
 #[derive(Copy, Clone)]
 pub(crate) enum OverlayKind {
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 19d98df3ce9..e4fcb287f12 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -11,8 +11,6 @@ use std::iter;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 
-use build_helper::{self, output, t};
-
 use crate::builder::{Builder, Compiler, Kind, RunConfig, ShouldRun, Step};
 use crate::cache::Interned;
 use crate::compile;
@@ -22,7 +20,7 @@ use crate::flags::Subcommand;
 use crate::native;
 use crate::tool::{self, SourceType, Tool};
 use crate::toolstate::ToolState;
-use crate::util::{self, add_link_lib_path, dylib_path, dylib_path_var};
+use crate::util::{self, add_link_lib_path, dylib_path, dylib_path_var, output, t};
 use crate::Crate as CargoCrate;
 use crate::{envify, CLang, DocTests, GitRepo, Mode};
 
@@ -2306,9 +2304,7 @@ impl Step for Distcheck {
                 .current_dir(&dir),
         );
         builder.run(
-            Command::new(build_helper::make(&builder.config.build.triple))
-                .arg("check")
-                .current_dir(&dir),
+            Command::new(util::make(&builder.config.build.triple)).arg("check").current_dir(&dir),
         );
 
         // Now make sure that rust-src has all of libstd's dependencies
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index 1317c3f9839..2ae4d830721 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -4,14 +4,12 @@ use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::{exit, Command};
 
-use build_helper::t;
-
 use crate::builder::{Builder, Cargo as CargoCommand, RunConfig, ShouldRun, Step};
 use crate::channel::GitInfo;
 use crate::compile;
 use crate::config::TargetSelection;
 use crate::toolstate::ToolState;
-use crate::util::{add_dylib_path, exe};
+use crate::util::{add_dylib_path, exe, t};
 use crate::Compiler;
 use crate::Mode;
 
diff --git a/src/bootstrap/toolstate.rs b/src/bootstrap/toolstate.rs
index 08d08158062..c7ea254c5b1 100644
--- a/src/bootstrap/toolstate.rs
+++ b/src/bootstrap/toolstate.rs
@@ -1,5 +1,5 @@
 use crate::builder::{Builder, RunConfig, ShouldRun, Step};
-use build_helper::t;
+use crate::util::t;
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::env;
diff --git a/src/bootstrap/util.rs b/src/bootstrap/util.rs
index 2c78ceb1e5b..8e770d4d57f 100644
--- a/src/bootstrap/util.rs
+++ b/src/bootstrap/util.rs
@@ -7,15 +7,38 @@ use std::env;
 use std::fs;
 use std::io;
 use std::path::{Path, PathBuf};
-use std::process::Command;
+use std::process::{Command, Stdio};
 use std::str;
-use std::time::Instant;
-
-use build_helper::t;
+use std::time::{Instant, SystemTime, UNIX_EPOCH};
 
 use crate::builder::Builder;
 use crate::config::{Config, TargetSelection};
 
+/// A helper macro to `unwrap` a result except also print out details like:
+///
+/// * The file/line of the panic
+/// * The expression that failed
+/// * The error itself
+///
+/// This is currently used judiciously throughout the build system rather than
+/// using a `Result` with `try!`, but this may change one day...
+macro_rules! t {
+    ($e:expr) => {
+        match $e {
+            Ok(e) => e,
+            Err(e) => panic!("{} failed with {}", stringify!($e), e),
+        }
+    };
+    // it can show extra info in the second parameter
+    ($e:expr, $extra:expr) => {
+        match $e {
+            Ok(e) => e,
+            Err(e) => panic!("{} failed with {} ({:?})", stringify!($e), e, $extra),
+        }
+    };
+}
+pub(crate) use t;
+
 /// Given an executable called `name`, return the filename for the
 /// executable for a particular target.
 pub fn exe(name: &str, target: TargetSelection) -> String {
@@ -301,3 +324,119 @@ pub fn is_valid_test_suite_arg<'a, P: AsRef<Path>>(
         _ => None,
     }
 }
+
+pub fn run(cmd: &mut Command, print_cmd_on_fail: bool) {
+    if !try_run(cmd, print_cmd_on_fail) {
+        std::process::exit(1);
+    }
+}
+
+pub fn try_run(cmd: &mut Command, print_cmd_on_fail: bool) -> bool {
+    let status = match cmd.status() {
+        Ok(status) => status,
+        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}", cmd, e)),
+    };
+    if !status.success() && print_cmd_on_fail {
+        println!(
+            "\n\ncommand did not execute successfully: {:?}\n\
+             expected success, got: {}\n\n",
+            cmd, status
+        );
+    }
+    status.success()
+}
+
+pub fn run_suppressed(cmd: &mut Command) {
+    if !try_run_suppressed(cmd) {
+        std::process::exit(1);
+    }
+}
+
+pub fn try_run_suppressed(cmd: &mut Command) -> bool {
+    let output = match cmd.output() {
+        Ok(status) => status,
+        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}", cmd, e)),
+    };
+    if !output.status.success() {
+        println!(
+            "\n\ncommand did not execute successfully: {:?}\n\
+             expected success, got: {}\n\n\
+             stdout ----\n{}\n\
+             stderr ----\n{}\n\n",
+            cmd,
+            output.status,
+            String::from_utf8_lossy(&output.stdout),
+            String::from_utf8_lossy(&output.stderr)
+        );
+    }
+    output.status.success()
+}
+
+pub fn make(host: &str) -> PathBuf {
+    if host.contains("dragonfly")
+        || host.contains("freebsd")
+        || host.contains("netbsd")
+        || host.contains("openbsd")
+    {
+        PathBuf::from("gmake")
+    } else {
+        PathBuf::from("make")
+    }
+}
+
+#[track_caller]
+pub fn output(cmd: &mut Command) -> String {
+    let output = match cmd.stderr(Stdio::inherit()).output() {
+        Ok(status) => status,
+        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}", cmd, e)),
+    };
+    if !output.status.success() {
+        panic!(
+            "command did not execute successfully: {:?}\n\
+             expected success, got: {}",
+            cmd, output.status
+        );
+    }
+    String::from_utf8(output.stdout).unwrap()
+}
+
+/// Returns the last-modified time for `path`, or zero if it doesn't exist.
+pub fn mtime(path: &Path) -> SystemTime {
+    fs::metadata(path).and_then(|f| f.modified()).unwrap_or(UNIX_EPOCH)
+}
+
+/// Returns `true` if `dst` is up to date given that the file or files in `src`
+/// are used to generate it.
+///
+/// Uses last-modified time checks to verify this.
+pub fn up_to_date(src: &Path, dst: &Path) -> bool {
+    if !dst.exists() {
+        return false;
+    }
+    let threshold = mtime(dst);
+    let meta = match fs::metadata(src) {
+        Ok(meta) => meta,
+        Err(e) => panic!("source {:?} failed to get metadata: {}", src, e),
+    };
+    if meta.is_dir() {
+        dir_up_to_date(src, threshold)
+    } else {
+        meta.modified().unwrap_or(UNIX_EPOCH) <= threshold
+    }
+}
+
+fn dir_up_to_date(src: &Path, threshold: SystemTime) -> bool {
+    t!(fs::read_dir(src)).map(|e| t!(e)).all(|e| {
+        let meta = t!(e.metadata());
+        if meta.is_dir() {
+            dir_up_to_date(&e.path(), threshold)
+        } else {
+            meta.modified().unwrap_or(UNIX_EPOCH) < threshold
+        }
+    })
+}
+
+fn fail(s: &str) -> ! {
+    println!("\n\n{}\n\n", s);
+    std::process::exit(1);
+}
diff --git a/src/build_helper/Cargo.toml b/src/build_helper/Cargo.toml
deleted file mode 100644
index d88df0e08fa..00000000000
--- a/src/build_helper/Cargo.toml
+++ /dev/null
@@ -1,7 +0,0 @@
-[package]
-name = "build_helper"
-version = "0.1.0"
-edition = "2021"
-
-[lib]
-path = "lib.rs"
diff --git a/src/build_helper/lib.rs b/src/build_helper/lib.rs
deleted file mode 100644
index 24aded54731..00000000000
--- a/src/build_helper/lib.rs
+++ /dev/null
@@ -1,189 +0,0 @@
-use std::ffi::{OsStr, OsString};
-use std::fmt::Display;
-use std::path::{Path, PathBuf};
-use std::process::{Command, Stdio};
-use std::time::{SystemTime, UNIX_EPOCH};
-use std::{env, fs};
-
-/// A helper macro to `unwrap` a result except also print out details like:
-///
-/// * The file/line of the panic
-/// * The expression that failed
-/// * The error itself
-///
-/// This is currently used judiciously throughout the build system rather than
-/// using a `Result` with `try!`, but this may change one day...
-#[macro_export]
-macro_rules! t {
-    ($e:expr) => {
-        match $e {
-            Ok(e) => e,
-            Err(e) => panic!("{} failed with {}", stringify!($e), e),
-        }
-    };
-    // it can show extra info in the second parameter
-    ($e:expr, $extra:expr) => {
-        match $e {
-            Ok(e) => e,
-            Err(e) => panic!("{} failed with {} ({:?})", stringify!($e), e, $extra),
-        }
-    };
-}
-
-/// Reads an environment variable and adds it to dependencies.
-/// Supposed to be used for all variables except those set for build scripts by cargo
-/// <https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts>
-pub fn tracked_env_var_os<K: AsRef<OsStr> + Display>(key: K) -> Option<OsString> {
-    println!("cargo:rerun-if-env-changed={}", key);
-    env::var_os(key)
-}
-
-// Because Cargo adds the compiler's dylib path to our library search path, llvm-config may
-// break: the dylib path for the compiler, as of this writing, contains a copy of the LLVM
-// shared library, which means that when our freshly built llvm-config goes to load it's
-// associated LLVM, it actually loads the compiler's LLVM. In particular when building the first
-// compiler (i.e., in stage 0) that's a problem, as the compiler's LLVM is likely different from
-// the one we want to use. As such, we restore the environment to what bootstrap saw. This isn't
-// perfect -- we might actually want to see something from Cargo's added library paths -- but
-// for now it works.
-pub fn restore_library_path() {
-    let key = tracked_env_var_os("REAL_LIBRARY_PATH_VAR").expect("REAL_LIBRARY_PATH_VAR");
-    if let Some(env) = tracked_env_var_os("REAL_LIBRARY_PATH") {
-        env::set_var(&key, &env);
-    } else {
-        env::remove_var(&key);
-    }
-}
-
-pub fn run(cmd: &mut Command, print_cmd_on_fail: bool) {
-    if !try_run(cmd, print_cmd_on_fail) {
-        std::process::exit(1);
-    }
-}
-
-pub fn try_run(cmd: &mut Command, print_cmd_on_fail: bool) -> bool {
-    let status = match cmd.status() {
-        Ok(status) => status,
-        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}", cmd, e)),
-    };
-    if !status.success() && print_cmd_on_fail {
-        println!(
-            "\n\ncommand did not execute successfully: {:?}\n\
-             expected success, got: {}\n\n",
-            cmd, status
-        );
-    }
-    status.success()
-}
-
-pub fn run_suppressed(cmd: &mut Command) {
-    if !try_run_suppressed(cmd) {
-        std::process::exit(1);
-    }
-}
-
-pub fn try_run_suppressed(cmd: &mut Command) -> bool {
-    let output = match cmd.output() {
-        Ok(status) => status,
-        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}", cmd, e)),
-    };
-    if !output.status.success() {
-        println!(
-            "\n\ncommand did not execute successfully: {:?}\n\
-             expected success, got: {}\n\n\
-             stdout ----\n{}\n\
-             stderr ----\n{}\n\n",
-            cmd,
-            output.status,
-            String::from_utf8_lossy(&output.stdout),
-            String::from_utf8_lossy(&output.stderr)
-        );
-    }
-    output.status.success()
-}
-
-pub fn make(host: &str) -> PathBuf {
-    if host.contains("dragonfly")
-        || host.contains("freebsd")
-        || host.contains("netbsd")
-        || host.contains("openbsd")
-    {
-        PathBuf::from("gmake")
-    } else {
-        PathBuf::from("make")
-    }
-}
-
-#[track_caller]
-pub fn output(cmd: &mut Command) -> String {
-    let output = match cmd.stderr(Stdio::inherit()).output() {
-        Ok(status) => status,
-        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}", cmd, e)),
-    };
-    if !output.status.success() {
-        panic!(
-            "command did not execute successfully: {:?}\n\
-             expected success, got: {}",
-            cmd, output.status
-        );
-    }
-    String::from_utf8(output.stdout).unwrap()
-}
-
-pub fn rerun_if_changed_anything_in_dir(dir: &Path) {
-    let mut stack = dir
-        .read_dir()
-        .unwrap()
-        .map(|e| e.unwrap())
-        .filter(|e| &*e.file_name() != ".git")
-        .collect::<Vec<_>>();
-    while let Some(entry) = stack.pop() {
-        let path = entry.path();
-        if entry.file_type().unwrap().is_dir() {
-            stack.extend(path.read_dir().unwrap().map(|e| e.unwrap()));
-        } else {
-            println!("cargo:rerun-if-changed={}", path.display());
-        }
-    }
-}
-
-/// Returns the last-modified time for `path`, or zero if it doesn't exist.
-pub fn mtime(path: &Path) -> SystemTime {
-    fs::metadata(path).and_then(|f| f.modified()).unwrap_or(UNIX_EPOCH)
-}
-
-/// Returns `true` if `dst` is up to date given that the file or files in `src`
-/// are used to generate it.
-///
-/// Uses last-modified time checks to verify this.
-pub fn up_to_date(src: &Path, dst: &Path) -> bool {
-    if !dst.exists() {
-        return false;
-    }
-    let threshold = mtime(dst);
-    let meta = match fs::metadata(src) {
-        Ok(meta) => meta,
-        Err(e) => panic!("source {:?} failed to get metadata: {}", src, e),
-    };
-    if meta.is_dir() {
-        dir_up_to_date(src, threshold)
-    } else {
-        meta.modified().unwrap_or(UNIX_EPOCH) <= threshold
-    }
-}
-
-fn dir_up_to_date(src: &Path, threshold: SystemTime) -> bool {
-    t!(fs::read_dir(src)).map(|e| t!(e)).all(|e| {
-        let meta = t!(e.metadata());
-        if meta.is_dir() {
-            dir_up_to_date(&e.path(), threshold)
-        } else {
-            meta.modified().unwrap_or(UNIX_EPOCH) < threshold
-        }
-    })
-}
-
-fn fail(s: &str) -> ! {
-    println!("\n\n{}\n\n", s);
-    std::process::exit(1);
-}