src/bootstrap/src/utils/helpers.rs - third_party/rust - Git at Google

 //! Various utility functions used throughout bootstrap.
 //!
 //! Simple things like testing the various filesystem operations here and there,
 //! not a lot of interesting happenings here unfortunately.

 use std::ffi::OsStr;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 use std::sync::OnceLock;
 use std::time::{Instant, SystemTime, UNIX_EPOCH};
 use std::{env, fs, io, str};

 use build_helper::util::fail;

 use crate::LldMode;
 use crate::core::builder::Builder;
 use crate::core::config::{Config, TargetSelection};
 pub use crate::utils::shared_helpers::{dylib_path, dylib_path_var};

 #[cfg(test)]
 mod tests;

 /// 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),
         }
     };
 }
 pub use t;

 use crate::utils::exec::{BootstrapCommand, command};

 pub fn exe(name: &str, target: TargetSelection) -> String {
     crate::utils::shared_helpers::exe(name, &target.triple)
 }

 /// Returns `true` if the file name given looks like a dynamic library.
 pub fn is_dylib(name: &str) -> bool {
     name.ends_with(".dylib") || name.ends_with(".so") || name.ends_with(".dll")
 }

 /// Returns `true` if the file name given looks like a debug info file
 pub fn is_debug_info(name: &str) -> bool {
     // FIXME: consider split debug info on other platforms (e.g., Linux, macOS)
     name.ends_with(".pdb")
 }

 /// Returns the corresponding relative library directory that the compiler's
 /// dylibs will be found in.
 pub fn libdir(target: TargetSelection) -> &'static str {
     if target.is_windows() { "bin" } else { "lib" }
 }

 /// Adds a list of lookup paths to `cmd`'s dynamic library lookup path.
 /// If the dylib_path_var is already set for this cmd, the old value will be overwritten!
 pub fn add_dylib_path(path: Vec<PathBuf>, cmd: &mut BootstrapCommand) {
     let mut list = dylib_path();
     for path in path {
         list.insert(0, path);
     }
     cmd.env(dylib_path_var(), t!(env::join_paths(list)));
 }

 /// Adds a list of lookup paths to `cmd`'s link library lookup path.
 pub fn add_link_lib_path(path: Vec<PathBuf>, cmd: &mut BootstrapCommand) {
     let mut list = link_lib_path();
     for path in path {
         list.insert(0, path);
     }
     cmd.env(link_lib_path_var(), t!(env::join_paths(list)));
 }

 /// Returns the environment variable which the link library lookup path
 /// resides in for this platform.
 fn link_lib_path_var() -> &'static str {
     if cfg!(target_env = "msvc") { "LIB" } else { "LIBRARY_PATH" }
 }

 /// Parses the `link_lib_path_var()` environment variable, returning a list of
 /// paths that are members of this lookup path.
 fn link_lib_path() -> Vec<PathBuf> {
     let var = match env::var_os(link_lib_path_var()) {
         Some(v) => v,
         None => return vec![],
     };
     env::split_paths(&var).collect()
 }

 pub struct TimeIt(bool, Instant);

 /// Returns an RAII structure that prints out how long it took to drop.
 pub fn timeit(builder: &Builder<'_>) -> TimeIt {
     TimeIt(builder.config.dry_run(), Instant::now())
 }

 impl Drop for TimeIt {
     fn drop(&mut self) {
         let time = self.1.elapsed();
         if !self.0 {
             println!("\tfinished in {}.{:03} seconds", time.as_secs(), time.subsec_millis());
         }
     }
 }

 /// Used for download caching
 pub(crate) fn program_out_of_date(stamp: &Path, key: &str) -> bool {
     if !stamp.exists() {
         return true;
     }
     t!(fs::read_to_string(stamp)) != key
 }

 /// Symlinks two directories, using junctions on Windows and normal symlinks on
 /// Unix.
 pub fn symlink_dir(config: &Config, original: &Path, link: &Path) -> io::Result<()> {
     if config.dry_run() {
         return Ok(());
     }
     let _ = fs::remove_dir_all(link);
     return symlink_dir_inner(original, link);

     #[cfg(not(windows))]
     fn symlink_dir_inner(original: &Path, link: &Path) -> io::Result<()> {
         use std::os::unix::fs;
         fs::symlink(original, link)
     }

     #[cfg(windows)]
     fn symlink_dir_inner(target: &Path, junction: &Path) -> io::Result<()> {
         junction::create(&target, &junction)
     }
 }

 /// Rename a file if from and to are in the same filesystem or
 /// copy and remove the file otherwise
 pub fn move_file<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
     match fs::rename(&from, &to) {
         // FIXME: Once `ErrorKind::CrossesDevices` is stabilized use
         // if e.kind() == io::ErrorKind::CrossesDevices {
         #[cfg(unix)]
         Err(e) if e.raw_os_error() == Some(libc::EXDEV) => {
             std::fs::copy(&from, &to)?;
             std::fs::remove_file(&from)
         }
         r => r,
     }
 }

 pub fn forcing_clang_based_tests() -> bool {
     if let Some(var) = env::var_os("RUSTBUILD_FORCE_CLANG_BASED_TESTS") {
         match &var.to_string_lossy().to_lowercase()[..] {
             "1" | "yes" | "on" => true,
             "0" | "no" | "off" => false,
             other => {
                 // Let's make sure typos don't go unnoticed
                 panic!(
                     "Unrecognized option '{other}' set in \
                         RUSTBUILD_FORCE_CLANG_BASED_TESTS"
                 )
             }
         }
     } else {
         false
     }
 }

 pub fn use_host_linker(target: TargetSelection) -> bool {
     // FIXME: this information should be gotten by checking the linker flavor
     // of the rustc target
     !(target.contains("emscripten")
         || target.contains("wasm32")
         || target.contains("nvptx")
         || target.contains("fortanix")
         || target.contains("fuchsia")
         || target.contains("bpf")
         || target.contains("switch"))
 }

 pub fn target_supports_cranelift_backend(target: TargetSelection) -> bool {
     if target.contains("linux") {
         target.contains("x86_64")
             || target.contains("aarch64")
             || target.contains("s390x")
             || target.contains("riscv64gc")
     } else if target.contains("darwin") {
         target.contains("x86_64") || target.contains("aarch64")
     } else if target.is_windows() {
         target.contains("x86_64")
     } else {
         false
     }
 }

 pub fn is_valid_test_suite_arg<'a, P: AsRef<Path>>(
     path: &'a Path,
     suite_path: P,
     builder: &Builder<'_>,
 ) -> Option<&'a str> {
     let suite_path = suite_path.as_ref();
     let path = match path.strip_prefix(".") {
         Ok(p) => p,
         Err(_) => path,
     };
     if !path.starts_with(suite_path) {
         return None;
     }
     let abs_path = builder.src.join(path);
     let exists = abs_path.is_dir() || abs_path.is_file();
     if !exists {
         panic!(
             "Invalid test suite filter \"{}\": file or directory does not exist",
             abs_path.display()
         );
     }
     // Since test suite paths are themselves directories, if we don't
     // specify a directory or file, we'll get an empty string here
     // (the result of the test suite directory without its suite prefix).
     // Therefore, we need to filter these out, as only the first --test-args
     // flag is respected, so providing an empty --test-args conflicts with
     // any following it.
     match path.strip_prefix(suite_path).ok().and_then(|p| p.to_str()) {
         Some(s) if !s.is_empty() => Some(s),
         _ => None,
     }
 }

 // FIXME: get rid of this function
 pub fn check_run(cmd: &mut BootstrapCommand, print_cmd_on_fail: bool) -> bool {
     let status = match cmd.as_command_mut().status() {
         Ok(status) => status,
         Err(e) => {
             println!("failed to execute command: {cmd:?}\nERROR: {e}");
             return false;
         }
     };
     if !status.success() && print_cmd_on_fail {
         println!(
             "\n\ncommand did not execute successfully: {cmd:?}\n\
              expected success, got: {status}\n\n"
         );
     }
     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: {cmd:?}\nERROR: {e}")),
     };
     if !output.status.success() {
         panic!(
             "command did not execute successfully: {:?}\n\
              expected success, got: {}",
             cmd, output.status
         );
     }
     String::from_utf8(output.stdout).unwrap()
 }

 /// Spawn a process and return a closure that will wait for the process
 /// to finish and then return its output. This allows the spawned process
 /// to do work without immediately blocking bootstrap.
 #[track_caller]
 pub fn start_process(cmd: &mut Command) -> impl FnOnce() -> String {
     let child = match cmd.stderr(Stdio::inherit()).stdout(Stdio::piped()).spawn() {
         Ok(child) => child,
         Err(e) => fail(&format!("failed to execute command: {cmd:?}\nERROR: {e}")),
     };

     let command = format!("{:?}", cmd);

     move || {
         let output = child.wait_with_output().unwrap();

         if !output.status.success() {
             panic!(
                 "command did not execute successfully: {}\n\
                  expected success, got: {}",
                 command, 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 {src:?} failed to get metadata: {e}"),
     };
     if meta.is_dir() {
         dir_up_to_date(src, threshold)
     } else {
         meta.modified().unwrap_or(UNIX_EPOCH) <= threshold
     }
 }

 /// Returns the filename without the hash prefix added by the cc crate.
 ///
 /// Since v1.0.78 of the cc crate, object files are prefixed with a 16-character hash
 /// to avoid filename collisions.
 pub fn unhashed_basename(obj: &Path) -> &str {
     let basename = obj.file_stem().unwrap().to_str().expect("UTF-8 file name");
     basename.split_once('-').unwrap().1
 }

 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
         }
     })
 }

 /// Adapted from <https://github.com/llvm/llvm-project/blob/782e91224601e461c019e0a4573bbccc6094fbcd/llvm/cmake/modules/HandleLLVMOptions.cmake#L1058-L1079>
 ///
 /// When `clang-cl` is used with instrumentation, we need to add clang's runtime library resource
 /// directory to the linker flags, otherwise there will be linker errors about the profiler runtime
 /// missing. This function returns the path to that directory.
 pub fn get_clang_cl_resource_dir(builder: &Builder<'_>, clang_cl_path: &str) -> PathBuf {
     // Similar to how LLVM does it, to find clang's library runtime directory:
     // - we ask `clang-cl` to locate the `clang_rt.builtins` lib.
     let mut builtins_locator = command(clang_cl_path);
     builtins_locator.args(["/clang:-print-libgcc-file-name", "/clang:--rtlib=compiler-rt"]);

     let clang_rt_builtins = builtins_locator.run_capture_stdout(builder).stdout();
     let clang_rt_builtins = Path::new(clang_rt_builtins.trim());
     assert!(
         clang_rt_builtins.exists(),
         "`clang-cl` must correctly locate the library runtime directory"
     );

     // - the profiler runtime will be located in the same directory as the builtins lib, like
     // `$LLVM_DISTRO_ROOT/lib/clang/$LLVM_VERSION/lib/windows`.
     let clang_rt_dir = clang_rt_builtins.parent().expect("The clang lib folder should exist");
     clang_rt_dir.to_path_buf()
 }

 /// Returns a flag that configures LLD to use only a single thread.
 /// If we use an external LLD, we need to find out which version is it to know which flag should we
 /// pass to it (LLD older than version 10 had a different flag).
 fn lld_flag_no_threads(builder: &Builder<'_>, lld_mode: LldMode, is_windows: bool) -> &'static str {
     static LLD_NO_THREADS: OnceLock<(&'static str, &'static str)> = OnceLock::new();

     let new_flags = ("/threads:1", "--threads=1");
     let old_flags = ("/no-threads", "--no-threads");

     let (windows_flag, other_flag) = LLD_NO_THREADS.get_or_init(|| {
         let newer_version = match lld_mode {
             LldMode::External => {
                 let mut cmd = command("lld");
                 cmd.arg("-flavor").arg("ld").arg("--version");
                 let out = cmd.run_capture_stdout(builder).stdout();
                 match (out.find(char::is_numeric), out.find('.')) {
                     (Some(b), Some(e)) => out.as_str()[b..e].parse::<i32>().ok().unwrap_or(14) > 10,
                     _ => true,
                 }
             }
             _ => true,
         };
         if newer_version { new_flags } else { old_flags }
     });
     if is_windows { windows_flag } else { other_flag }
 }

 pub fn dir_is_empty(dir: &Path) -> bool {
     t!(std::fs::read_dir(dir)).next().is_none()
 }

 /// Extract the beta revision from the full version string.
 ///
 /// The full version string looks like "a.b.c-beta.y". And we need to extract
 /// the "y" part from the string.
 pub fn extract_beta_rev(version: &str) -> Option<String> {
     let parts = version.splitn(2, "-beta.").collect::<Vec<_>>();
     let count = parts.get(1).and_then(|s| s.find(' ').map(|p| s[..p].to_string()));

     count
 }

 pub enum LldThreads {
     Yes,
     No,
 }

 /// Returns the linker arguments for rustc/rustdoc for the given builder and target.
 pub fn linker_args(
     builder: &Builder<'_>,
     target: TargetSelection,
     lld_threads: LldThreads,
 ) -> Vec<String> {
     let mut args = linker_flags(builder, target, lld_threads);

     if let Some(linker) = builder.linker(target) {
         args.push(format!("-Clinker={}", linker.display()));
     }

     args
 }

 /// Returns the linker arguments for rustc/rustdoc for the given builder and target, without the
 /// -Clinker flag.
 pub fn linker_flags(
     builder: &Builder<'_>,
     target: TargetSelection,
     lld_threads: LldThreads,
 ) -> Vec<String> {
     let mut args = vec![];
     if !builder.is_lld_direct_linker(target) && builder.config.lld_mode.is_used() {
         args.push(String::from("-Clink-arg=-fuse-ld=lld"));

         if matches!(lld_threads, LldThreads::No) {
             args.push(format!(
                 "-Clink-arg=-Wl,{}",
                 lld_flag_no_threads(builder, builder.config.lld_mode, target.is_windows())
             ));
         }
     }
     args
 }

 pub fn add_rustdoc_cargo_linker_args(
     cmd: &mut BootstrapCommand,
     builder: &Builder<'_>,
     target: TargetSelection,
     lld_threads: LldThreads,
 ) {
     let args = linker_args(builder, target, lld_threads);
     let mut flags = cmd
         .get_envs()
         .find_map(|(k, v)| if k == OsStr::new("RUSTDOCFLAGS") { v } else { None })
         .unwrap_or_default()
         .to_os_string();
     for arg in args {
         if !flags.is_empty() {
             flags.push(" ");
         }
         flags.push(arg);
     }
     if !flags.is_empty() {
         cmd.env("RUSTDOCFLAGS", flags);
     }
 }

 /// Converts `T` into a hexadecimal `String`.
 pub fn hex_encode<T>(input: T) -> String
 where
     T: AsRef<[u8]>,
 {
     use std::fmt::Write;

     input.as_ref().iter().fold(String::with_capacity(input.as_ref().len() * 2), |mut acc, &byte| {
         write!(&mut acc, "{:02x}", byte).expect("Failed to write byte to the hex String.");
         acc
     })
 }

 /// Create a `--check-cfg` argument invocation for a given name
 /// and it's values.
 pub fn check_cfg_arg(name: &str, values: Option<&[&str]>) -> String {
     // Creating a string of the values by concatenating each value:
     // ',values("tvos","watchos")' or '' (nothing) when there are no values.
     let next = match values {
         Some(values) => {
             let mut tmp = values.iter().flat_map(|val| [",", "\"", val, "\""]).collect::<String>();

             tmp.insert_str(1, "values(");
             tmp.push(')');
             tmp
         }
         None => "".to_string(),
     };
     format!("--check-cfg=cfg({name}{next})")
 }

 /// Prepares `BootstrapCommand` that runs git inside the source directory if given.
 ///
 /// Whenever a git invocation is needed, this function should be preferred over
 /// manually building a git `BootstrapCommand`. This approach allows us to manage
 /// bootstrap-specific needs/hacks from a single source, rather than applying them on next to every
 /// git command creation, which is painful to ensure that the required change is applied
 /// on each one of them correctly.
 #[track_caller]
 pub fn git(source_dir: Option<&Path>) -> BootstrapCommand {
     let mut git = command("git");

     if let Some(source_dir) = source_dir {
         git.current_dir(source_dir);
         // If we are running inside git (e.g. via a hook), `GIT_DIR` is set and takes precedence
         // over the current dir. Un-set it to make the current dir matter.
         git.env_remove("GIT_DIR");
         // Also un-set some other variables, to be on the safe side (based on cargo's
         // `fetch_with_cli`). In particular un-setting `GIT_INDEX_FILE` is required to fix some odd
         // misbehavior.
         git.env_remove("GIT_WORK_TREE")
             .env_remove("GIT_INDEX_FILE")
             .env_remove("GIT_OBJECT_DIRECTORY")
             .env_remove("GIT_ALTERNATE_OBJECT_DIRECTORIES");
     }

     git
 }

 /// Sets the file times for a given file at `path`.
 pub fn set_file_times<P: AsRef<Path>>(path: P, times: fs::FileTimes) -> io::Result<()> {
     // Windows requires file to be writable to modify file times. But on Linux CI the file does not
     // need to be writable to modify file times and might be read-only.
     let f = if cfg!(windows) {
         fs::File::options().write(true).open(path)?
     } else {
         fs::File::open(path)?
     };
     f.set_times(times)
 }

 pub struct HashStamp {
     pub path: PathBuf,
     pub hash: Option<Vec<u8>>,
 }

 impl HashStamp {
     pub fn new(path: PathBuf, hash: Option<&str>) -> Self {
         HashStamp { path, hash: hash.map(|s| s.as_bytes().to_owned()) }
     }

     pub fn is_done(&self) -> bool {
         match fs::read(&self.path) {
             Ok(h) => self.hash.as_deref().unwrap_or(b"") == h.as_slice(),
             Err(e) if e.kind() == io::ErrorKind::NotFound => false,
             Err(e) => {
                 panic!("failed to read stamp file `{}`: {}", self.path.display(), e);
             }
         }
     }

     pub fn remove(&self) -> io::Result<()> {
         match fs::remove_file(&self.path) {
             Ok(()) => Ok(()),
             Err(e) => {
                 if e.kind() == io::ErrorKind::NotFound {
                     Ok(())
                 } else {
                     Err(e)
                 }
             }
         }
     }

     pub fn write(&self) -> io::Result<()> {
         fs::write(&self.path, self.hash.as_deref().unwrap_or(b""))
     }
 }
	//! Various utility functions used throughout bootstrap.
	//!
	//! Simple things like testing the various filesystem operations here and there,
	//! not a lot of interesting happenings here unfortunately.

	use std::ffi::OsStr;
	use std::path::{Path, PathBuf};
	use std::process::{Command, Stdio};
	use std::sync::OnceLock;
	use std::time::{Instant, SystemTime, UNIX_EPOCH};
	use std::{env, fs, io, str};

	use build_helper::util::fail;

	use crate::LldMode;
	use crate::core::builder::Builder;
	use crate::core::config::{Config, TargetSelection};
	pub use crate::utils::shared_helpers::{dylib_path, dylib_path_var};

	#[cfg(test)]
	mod tests;

	/// 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),
	}
	};
	}
	pub use t;

	use crate::utils::exec::{BootstrapCommand, command};

	pub fn exe(name: &str, target: TargetSelection) -> String {
	crate::utils::shared_helpers::exe(name, &target.triple)
	}

	/// Returns `true` if the file name given looks like a dynamic library.
	pub fn is_dylib(name: &str) -> bool {
	name.ends_with(".dylib") \|\| name.ends_with(".so") \|\| name.ends_with(".dll")
	}

	/// Returns `true` if the file name given looks like a debug info file
	pub fn is_debug_info(name: &str) -> bool {
	// FIXME: consider split debug info on other platforms (e.g., Linux, macOS)
	name.ends_with(".pdb")
	}

	/// Returns the corresponding relative library directory that the compiler's
	/// dylibs will be found in.
	pub fn libdir(target: TargetSelection) -> &'static str {
	if target.is_windows() { "bin" } else { "lib" }
	}

	/// Adds a list of lookup paths to `cmd`'s dynamic library lookup path.
	/// If the dylib_path_var is already set for this cmd, the old value will be overwritten!
	pub fn add_dylib_path(path: Vec<PathBuf>, cmd: &mut BootstrapCommand) {
	let mut list = dylib_path();
	for path in path {
	list.insert(0, path);
	}
	cmd.env(dylib_path_var(), t!(env::join_paths(list)));
	}

	/// Adds a list of lookup paths to `cmd`'s link library lookup path.
	pub fn add_link_lib_path(path: Vec<PathBuf>, cmd: &mut BootstrapCommand) {
	let mut list = link_lib_path();
	for path in path {
	list.insert(0, path);
	}
	cmd.env(link_lib_path_var(), t!(env::join_paths(list)));
	}

	/// Returns the environment variable which the link library lookup path
	/// resides in for this platform.
	fn link_lib_path_var() -> &'static str {
	if cfg!(target_env = "msvc") { "LIB" } else { "LIBRARY_PATH" }
	}

	/// Parses the `link_lib_path_var()` environment variable, returning a list of
	/// paths that are members of this lookup path.
	fn link_lib_path() -> Vec<PathBuf> {
	let var = match env::var_os(link_lib_path_var()) {
	Some(v) => v,
	None => return vec![],
	};
	env::split_paths(&var).collect()
	}

	pub struct TimeIt(bool, Instant);

	/// Returns an RAII structure that prints out how long it took to drop.
	pub fn timeit(builder: &Builder<'_>) -> TimeIt {
	TimeIt(builder.config.dry_run(), Instant::now())
	}

	impl Drop for TimeIt {
	fn drop(&mut self) {
	let time = self.1.elapsed();
	if !self.0 {
	println!("\tfinished in {}.{:03} seconds", time.as_secs(), time.subsec_millis());
	}
	}
	}

	/// Used for download caching
	pub(crate) fn program_out_of_date(stamp: &Path, key: &str) -> bool {
	if !stamp.exists() {
	return true;
	}
	t!(fs::read_to_string(stamp)) != key
	}

	/// Symlinks two directories, using junctions on Windows and normal symlinks on
	/// Unix.
	pub fn symlink_dir(config: &Config, original: &Path, link: &Path) -> io::Result<()> {
	if config.dry_run() {
	return Ok(());
	}
	let _ = fs::remove_dir_all(link);
	return symlink_dir_inner(original, link);

	#[cfg(not(windows))]
	fn symlink_dir_inner(original: &Path, link: &Path) -> io::Result<()> {
	use std::os::unix::fs;
	fs::symlink(original, link)
	}

	#[cfg(windows)]
	fn symlink_dir_inner(target: &Path, junction: &Path) -> io::Result<()> {
	junction::create(&target, &junction)
	}
	}

	/// Rename a file if from and to are in the same filesystem or
	/// copy and remove the file otherwise
	pub fn move_file<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
	match fs::rename(&from, &to) {
	// FIXME: Once `ErrorKind::CrossesDevices` is stabilized use
	// if e.kind() == io::ErrorKind::CrossesDevices {
	#[cfg(unix)]
	Err(e) if e.raw_os_error() == Some(libc::EXDEV) => {
	std::fs::copy(&from, &to)?;
	std::fs::remove_file(&from)
	}
	r => r,
	}
	}

	pub fn forcing_clang_based_tests() -> bool {
	if let Some(var) = env::var_os("RUSTBUILD_FORCE_CLANG_BASED_TESTS") {
	match &var.to_string_lossy().to_lowercase()[..] {
	"1" \| "yes" \| "on" => true,
	"0" \| "no" \| "off" => false,
	other => {
	// Let's make sure typos don't go unnoticed
	panic!(
	"Unrecognized option '{other}' set in \
	RUSTBUILD_FORCE_CLANG_BASED_TESTS"
	)
	}
	}
	} else {
	false
	}
	}

	pub fn use_host_linker(target: TargetSelection) -> bool {
	// FIXME: this information should be gotten by checking the linker flavor
	// of the rustc target
	!(target.contains("emscripten")
	\|\| target.contains("wasm32")
	\|\| target.contains("nvptx")
	\|\| target.contains("fortanix")
	\|\| target.contains("fuchsia")
	\|\| target.contains("bpf")
	\|\| target.contains("switch"))
	}

	pub fn target_supports_cranelift_backend(target: TargetSelection) -> bool {
	if target.contains("linux") {
	target.contains("x86_64")
	\|\| target.contains("aarch64")
	\|\| target.contains("s390x")
	\|\| target.contains("riscv64gc")
	} else if target.contains("darwin") {
	target.contains("x86_64") \|\| target.contains("aarch64")
	} else if target.is_windows() {
	target.contains("x86_64")
	} else {
	false
	}
	}

	pub fn is_valid_test_suite_arg<'a, P: AsRef<Path>>(
	path: &'a Path,
	suite_path: P,
	builder: &Builder<'_>,
	) -> Option<&'a str> {
	let suite_path = suite_path.as_ref();
	let path = match path.strip_prefix(".") {
	Ok(p) => p,
	Err(_) => path,
	};
	if !path.starts_with(suite_path) {
	return None;
	}
	let abs_path = builder.src.join(path);
	let exists = abs_path.is_dir() \|\| abs_path.is_file();
	if !exists {
	panic!(
	"Invalid test suite filter \"{}\": file or directory does not exist",
	abs_path.display()
	);
	}
	// Since test suite paths are themselves directories, if we don't
	// specify a directory or file, we'll get an empty string here
	// (the result of the test suite directory without its suite prefix).
	// Therefore, we need to filter these out, as only the first --test-args
	// flag is respected, so providing an empty --test-args conflicts with
	// any following it.
	match path.strip_prefix(suite_path).ok().and_then(\|p\| p.to_str()) {
	Some(s) if !s.is_empty() => Some(s),
	_ => None,
	}
	}

	// FIXME: get rid of this function
	pub fn check_run(cmd: &mut BootstrapCommand, print_cmd_on_fail: bool) -> bool {
	let status = match cmd.as_command_mut().status() {
	Ok(status) => status,
	Err(e) => {
	println!("failed to execute command: {cmd:?}\nERROR: {e}");
	return false;
	}
	};
	if !status.success() && print_cmd_on_fail {
	println!(
	"\n\ncommand did not execute successfully: {cmd:?}\n\
	expected success, got: {status}\n\n"
	);
	}
	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: {cmd:?}\nERROR: {e}")),
	};
	if !output.status.success() {
	panic!(
	"command did not execute successfully: {:?}\n\
	expected success, got: {}",
	cmd, output.status
	);
	}
	String::from_utf8(output.stdout).unwrap()
	}

	/// Spawn a process and return a closure that will wait for the process
	/// to finish and then return its output. This allows the spawned process
	/// to do work without immediately blocking bootstrap.
	#[track_caller]
	pub fn start_process(cmd: &mut Command) -> impl FnOnce() -> String {
	let child = match cmd.stderr(Stdio::inherit()).stdout(Stdio::piped()).spawn() {
	Ok(child) => child,
	Err(e) => fail(&format!("failed to execute command: {cmd:?}\nERROR: {e}")),
	};

	let command = format!("{:?}", cmd);

	move \|\| {
	let output = child.wait_with_output().unwrap();

	if !output.status.success() {
	panic!(
	"command did not execute successfully: {}\n\
	expected success, got: {}",
	command, 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 {src:?} failed to get metadata: {e}"),
	};
	if meta.is_dir() {
	dir_up_to_date(src, threshold)
	} else {
	meta.modified().unwrap_or(UNIX_EPOCH) <= threshold
	}
	}

	/// Returns the filename without the hash prefix added by the cc crate.
	///
	/// Since v1.0.78 of the cc crate, object files are prefixed with a 16-character hash
	/// to avoid filename collisions.
	pub fn unhashed_basename(obj: &Path) -> &str {
	let basename = obj.file_stem().unwrap().to_str().expect("UTF-8 file name");
	basename.split_once('-').unwrap().1
	}

	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
	}
	})
	}

	/// Adapted from <https://github.com/llvm/llvm-project/blob/782e91224601e461c019e0a4573bbccc6094fbcd/llvm/cmake/modules/HandleLLVMOptions.cmake#L1058-L1079>
	///
	/// When `clang-cl` is used with instrumentation, we need to add clang's runtime library resource
	/// directory to the linker flags, otherwise there will be linker errors about the profiler runtime
	/// missing. This function returns the path to that directory.
	pub fn get_clang_cl_resource_dir(builder: &Builder<'_>, clang_cl_path: &str) -> PathBuf {
	// Similar to how LLVM does it, to find clang's library runtime directory:
	// - we ask `clang-cl` to locate the `clang_rt.builtins` lib.
	let mut builtins_locator = command(clang_cl_path);
	builtins_locator.args(["/clang:-print-libgcc-file-name", "/clang:--rtlib=compiler-rt"]);

	let clang_rt_builtins = builtins_locator.run_capture_stdout(builder).stdout();
	let clang_rt_builtins = Path::new(clang_rt_builtins.trim());
	assert!(
	clang_rt_builtins.exists(),
	"`clang-cl` must correctly locate the library runtime directory"
	);

	// - the profiler runtime will be located in the same directory as the builtins lib, like
	// `$LLVM_DISTRO_ROOT/lib/clang/$LLVM_VERSION/lib/windows`.
	let clang_rt_dir = clang_rt_builtins.parent().expect("The clang lib folder should exist");
	clang_rt_dir.to_path_buf()
	}

	/// Returns a flag that configures LLD to use only a single thread.
	/// If we use an external LLD, we need to find out which version is it to know which flag should we
	/// pass to it (LLD older than version 10 had a different flag).
	fn lld_flag_no_threads(builder: &Builder<'_>, lld_mode: LldMode, is_windows: bool) -> &'static str {
	static LLD_NO_THREADS: OnceLock<(&'static str, &'static str)> = OnceLock::new();

	let new_flags = ("/threads:1", "--threads=1");
	let old_flags = ("/no-threads", "--no-threads");

	let (windows_flag, other_flag) = LLD_NO_THREADS.get_or_init(\|\| {
	let newer_version = match lld_mode {
	LldMode::External => {
	let mut cmd = command("lld");
	cmd.arg("-flavor").arg("ld").arg("--version");
	let out = cmd.run_capture_stdout(builder).stdout();
	match (out.find(char::is_numeric), out.find('.')) {
	(Some(b), Some(e)) => out.as_str()[b..e].parse::<i32>().ok().unwrap_or(14) > 10,
	_ => true,
	}
	}
	_ => true,
	};
	if newer_version { new_flags } else { old_flags }
	});
	if is_windows { windows_flag } else { other_flag }
	}

	pub fn dir_is_empty(dir: &Path) -> bool {
	t!(std::fs::read_dir(dir)).next().is_none()
	}

	/// Extract the beta revision from the full version string.
	///
	/// The full version string looks like "a.b.c-beta.y". And we need to extract
	/// the "y" part from the string.
	pub fn extract_beta_rev(version: &str) -> Option<String> {
	let parts = version.splitn(2, "-beta.").collect::<Vec<_>>();
	let count = parts.get(1).and_then(\|s\| s.find(' ').map(\|p\| s[..p].to_string()));

	count
	}

	pub enum LldThreads {
	Yes,
	No,
	}

	/// Returns the linker arguments for rustc/rustdoc for the given builder and target.
	pub fn linker_args(
	builder: &Builder<'_>,
	target: TargetSelection,
	lld_threads: LldThreads,
	) -> Vec<String> {
	let mut args = linker_flags(builder, target, lld_threads);

	if let Some(linker) = builder.linker(target) {
	args.push(format!("-Clinker={}", linker.display()));
	}

	args
	}

	/// Returns the linker arguments for rustc/rustdoc for the given builder and target, without the
	/// -Clinker flag.
	pub fn linker_flags(
	builder: &Builder<'_>,
	target: TargetSelection,
	lld_threads: LldThreads,
	) -> Vec<String> {
	let mut args = vec![];
	if !builder.is_lld_direct_linker(target) && builder.config.lld_mode.is_used() {
	args.push(String::from("-Clink-arg=-fuse-ld=lld"));

	if matches!(lld_threads, LldThreads::No) {
	args.push(format!(
	"-Clink-arg=-Wl,{}",
	lld_flag_no_threads(builder, builder.config.lld_mode, target.is_windows())
	));
	}
	}
	args
	}

	pub fn add_rustdoc_cargo_linker_args(
	cmd: &mut BootstrapCommand,
	builder: &Builder<'_>,
	target: TargetSelection,
	lld_threads: LldThreads,
	) {
	let args = linker_args(builder, target, lld_threads);
	let mut flags = cmd
	.get_envs()
	.find_map(\|(k, v)\| if k == OsStr::new("RUSTDOCFLAGS") { v } else { None })
	.unwrap_or_default()
	.to_os_string();
	for arg in args {
	if !flags.is_empty() {
	flags.push(" ");
	}
	flags.push(arg);
	}
	if !flags.is_empty() {
	cmd.env("RUSTDOCFLAGS", flags);
	}
	}

	/// Converts `T` into a hexadecimal `String`.
	pub fn hex_encode<T>(input: T) -> String
	where
	T: AsRef<[u8]>,
	{
	use std::fmt::Write;

	input.as_ref().iter().fold(String::with_capacity(input.as_ref().len() * 2), \|mut acc, &byte\| {
	write!(&mut acc, "{:02x}", byte).expect("Failed to write byte to the hex String.");
	acc
	})
	}

	/// Create a `--check-cfg` argument invocation for a given name
	/// and it's values.
	pub fn check_cfg_arg(name: &str, values: Option<&[&str]>) -> String {
	// Creating a string of the values by concatenating each value:
	// ',values("tvos","watchos")' or '' (nothing) when there are no values.
	let next = match values {
	Some(values) => {
	let mut tmp = values.iter().flat_map(\|val\| [",", "\"", val, "\""]).collect::<String>();

	tmp.insert_str(1, "values(");
	tmp.push(')');
	tmp
	}
	None => "".to_string(),
	};
	format!("--check-cfg=cfg({name}{next})")
	}

	/// Prepares `BootstrapCommand` that runs git inside the source directory if given.
	///
	/// Whenever a git invocation is needed, this function should be preferred over
	/// manually building a git `BootstrapCommand`. This approach allows us to manage
	/// bootstrap-specific needs/hacks from a single source, rather than applying them on next to every
	/// git command creation, which is painful to ensure that the required change is applied
	/// on each one of them correctly.
	#[track_caller]
	pub fn git(source_dir: Option<&Path>) -> BootstrapCommand {
	let mut git = command("git");

	if let Some(source_dir) = source_dir {
	git.current_dir(source_dir);
	// If we are running inside git (e.g. via a hook), `GIT_DIR` is set and takes precedence
	// over the current dir. Un-set it to make the current dir matter.
	git.env_remove("GIT_DIR");
	// Also un-set some other variables, to be on the safe side (based on cargo's
	// `fetch_with_cli`). In particular un-setting `GIT_INDEX_FILE` is required to fix some odd
	// misbehavior.
	git.env_remove("GIT_WORK_TREE")
	.env_remove("GIT_INDEX_FILE")
	.env_remove("GIT_OBJECT_DIRECTORY")
	.env_remove("GIT_ALTERNATE_OBJECT_DIRECTORIES");
	}

	git
	}

	/// Sets the file times for a given file at `path`.
	pub fn set_file_times<P: AsRef<Path>>(path: P, times: fs::FileTimes) -> io::Result<()> {
	// Windows requires file to be writable to modify file times. But on Linux CI the file does not
	// need to be writable to modify file times and might be read-only.
	let f = if cfg!(windows) {
	fs::File::options().write(true).open(path)?
	} else {
	fs::File::open(path)?
	};
	f.set_times(times)
	}

	pub struct HashStamp {
	pub path: PathBuf,
	pub hash: Option<Vec<u8>>,
	}

	impl HashStamp {
	pub fn new(path: PathBuf, hash: Option<&str>) -> Self {
	HashStamp { path, hash: hash.map(\|s\| s.as_bytes().to_owned()) }
	}

	pub fn is_done(&self) -> bool {
	match fs::read(&self.path) {
	Ok(h) => self.hash.as_deref().unwrap_or(b"") == h.as_slice(),
	Err(e) if e.kind() == io::ErrorKind::NotFound => false,
	Err(e) => {
	panic!("failed to read stamp file `{}`: {}", self.path.display(), e);
	}
	}
	}

	pub fn remove(&self) -> io::Result<()> {
	match fs::remove_file(&self.path) {
	Ok(()) => Ok(()),
	Err(e) => {
	if e.kind() == io::ErrorKind::NotFound {
	Ok(())
	} else {
	Err(e)
	}
	}
	}
	}

	pub fn write(&self) -> io::Result<()> {
	fs::write(&self.path, self.hash.as_deref().unwrap_or(b""))
	}
	}