Auto merge of #17259 - lnicola:sync-from-rust, r=lnicola

internal: Sync from downstream

6 files changed, 2298 insertions, 0 deletions

diff --git a/compiler/rustc_driver_impl/src/args.rs b/compiler/rustc_driver_impl/src/args.rs
new file mode 100644
index 00000000000..28574457389
--- /dev/null
+++ b/compiler/rustc_driver_impl/src/args.rs
@@ -0,0 +1,156 @@
+use std::{env, error, fmt, fs, io};
+
+use rustc_session::EarlyDiagCtxt;
+use rustc_span::ErrorGuaranteed;
+
+/// Expands argfiles in command line arguments.
+#[derive(Default)]
+struct Expander {
+    shell_argfiles: bool,
+    next_is_unstable_option: bool,
+    expanded: Vec<String>,
+}
+
+impl Expander {
+    /// Handles the next argument. If the argument is an argfile, it is expanded
+    /// inline.
+    fn arg(&mut self, arg: &str) -> Result<(), Error> {
+        if let Some(argfile) = arg.strip_prefix('@') {
+            match argfile.split_once(':') {
+                Some(("shell", path)) if self.shell_argfiles => {
+                    shlex::split(&Self::read_file(path)?)
+                        .ok_or_else(|| Error::ShellParseError(path.to_string()))?
+                        .into_iter()
+                        .for_each(|arg| self.push(arg));
+                }
+                _ => {
+                    let contents = Self::read_file(argfile)?;
+                    contents.lines().for_each(|arg| self.push(arg.to_string()));
+                }
+            }
+        } else {
+            self.push(arg.to_string());
+        }
+
+        Ok(())
+    }
+
+    /// Adds a command line argument verbatim with no argfile expansion.
+    fn push(&mut self, arg: String) {
+        // Unfortunately, we have to do some eager argparsing to handle unstable
+        // options which change the behavior of argfile arguments.
+        //
+        // Normally, all of the argfile arguments (e.g. `@args.txt`) are
+        // expanded into our arguments list *and then* the whole list of
+        // arguments are passed on to be parsed. However, argfile parsing
+        // options like `-Zshell_argfiles` need to change the behavior of that
+        // argument expansion. So we have to do a little parsing on our own here
+        // instead of leaning on the existing logic.
+        //
+        // All we care about are unstable options, so we parse those out and
+        // look for any that affect how we expand argfiles. This argument
+        // inspection is very conservative; we only change behavior when we see
+        // exactly the options we're looking for and everything gets passed
+        // through.
+
+        if self.next_is_unstable_option {
+            self.inspect_unstable_option(&arg);
+            self.next_is_unstable_option = false;
+        } else if let Some(unstable_option) = arg.strip_prefix("-Z") {
+            if unstable_option.is_empty() {
+                self.next_is_unstable_option = true;
+            } else {
+                self.inspect_unstable_option(unstable_option);
+            }
+        }
+
+        self.expanded.push(arg);
+    }
+
+    /// Consumes the `Expander`, returning the expanded arguments.
+    fn finish(self) -> Vec<String> {
+        self.expanded
+    }
+
+    /// Parses any relevant unstable flags specified on the command line.
+    fn inspect_unstable_option(&mut self, option: &str) {
+        match option {
+            "shell-argfiles" => self.shell_argfiles = true,
+            _ => (),
+        }
+    }
+
+    /// Reads the contents of a file as UTF-8.
+    fn read_file(path: &str) -> Result<String, Error> {
+        fs::read_to_string(path).map_err(|e| {
+            if e.kind() == io::ErrorKind::InvalidData {
+                Error::Utf8Error(path.to_string())
+            } else {
+                Error::IOError(path.to_string(), e)
+            }
+        })
+    }
+}
+
+/// Replaces any `@file` arguments with the contents of `file`, with each line of `file` as a
+/// separate argument.
+///
+/// **Note:** This function doesn't interpret argument 0 in any special way.
+/// If this function is intended to be used with command line arguments,
+/// `argv[0]` must be removed prior to calling it manually.
+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
+pub fn arg_expand_all(
+    early_dcx: &EarlyDiagCtxt,
+    at_args: &[String],
+) -> Result<Vec<String>, ErrorGuaranteed> {
+    let mut expander = Expander::default();
+    let mut result = Ok(());
+    for arg in at_args {
+        if let Err(err) = expander.arg(arg) {
+            result = Err(early_dcx.early_err(format!("failed to load argument file: {err}")));
+        }
+    }
+    result.map(|()| expander.finish())
+}
+
+/// Gets the raw unprocessed command-line arguments as Unicode strings, without doing any further
+/// processing (e.g., without `@file` expansion).
+///
+/// This function is identical to [`env::args()`] except that it emits an error when it encounters
+/// non-Unicode arguments instead of panicking.
+pub fn raw_args(early_dcx: &EarlyDiagCtxt) -> Result<Vec<String>, ErrorGuaranteed> {
+    let mut res = Ok(Vec::new());
+    for (i, arg) in env::args_os().enumerate() {
+        match arg.into_string() {
+            Ok(arg) => {
+                if let Ok(args) = &mut res {
+                    args.push(arg);
+                }
+            }
+            Err(arg) => {
+                res =
+                    Err(early_dcx.early_err(format!("argument {i} is not valid Unicode: {arg:?}")))
+            }
+        }
+    }
+    res
+}
+
+#[derive(Debug)]
+enum Error {
+    Utf8Error(String),
+    IOError(String, io::Error),
+    ShellParseError(String),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::Utf8Error(path) => write!(fmt, "UTF-8 error in {path}"),
+            Error::IOError(path, err) => write!(fmt, "IO error: {path}: {err}"),
+            Error::ShellParseError(path) => write!(fmt, "invalid shell-style arguments in {path}"),
+        }
+    }
+}
+
+impl error::Error for Error {}
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
new file mode 100644
index 00000000000..ba6b9ef0784
--- /dev/null
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -0,0 +1,1539 @@
+//! The Rust compiler.
+//!
+//! # Note
+//!
+//! This API is completely unstable and subject to change.
+
+#![allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![doc(rust_logo)]
+#![feature(rustdoc_internals)]
+#![allow(internal_features)]
+#![feature(decl_macro)]
+#![feature(let_chains)]
+#![feature(panic_backtrace_config)]
+#![feature(panic_update_hook)]
+#![feature(result_flattening)]
+
+use rustc_ast as ast;
+use rustc_codegen_ssa::{traits::CodegenBackend, CodegenErrors, CodegenResults};
+use rustc_const_eval::CTRL_C_RECEIVED;
+use rustc_data_structures::profiling::{
+    get_resident_set_size, print_time_passes_entry, TimePassesFormat,
+};
+use rustc_errors::emitter::stderr_destination;
+use rustc_errors::registry::Registry;
+use rustc_errors::{
+    markdown, ColorConfig, DiagCtxt, ErrCode, ErrorGuaranteed, FatalError, PResult,
+};
+use rustc_feature::find_gated_cfg;
+use rustc_interface::util::{self, get_codegen_backend};
+use rustc_interface::{interface, Queries};
+use rustc_lint::unerased_lint_store;
+use rustc_metadata::creader::MetadataLoader;
+use rustc_metadata::locator;
+use rustc_session::config::{nightly_options, CG_OPTIONS, Z_OPTIONS};
+use rustc_session::config::{ErrorOutputType, Input, OutFileName, OutputType};
+use rustc_session::getopts::{self, Matches};
+use rustc_session::lint::{Lint, LintId};
+use rustc_session::output::collect_crate_types;
+use rustc_session::{config, filesearch, EarlyDiagCtxt, Session};
+use rustc_span::def_id::LOCAL_CRATE;
+use rustc_span::source_map::FileLoader;
+use rustc_span::symbol::sym;
+use rustc_span::FileName;
+use rustc_target::json::ToJson;
+use rustc_target::spec::{Target, TargetTriple};
+use std::cmp::max;
+use std::collections::BTreeMap;
+use std::env;
+use std::ffi::OsString;
+use std::fmt::Write as _;
+use std::fs::{self, File};
+use std::io::{self, IsTerminal, Read, Write};
+use std::panic::{self, catch_unwind, PanicInfo};
+use std::path::PathBuf;
+use std::process::{self, Command, Stdio};
+use std::str;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{Arc, OnceLock};
+use std::time::{Instant, SystemTime};
+use time::OffsetDateTime;
+use tracing::trace;
+
+#[allow(unused_macros)]
+macro do_not_use_print($($t:tt)*) {
+    std::compile_error!(
+        "Don't use `print` or `println` here, use `safe_print` or `safe_println` instead"
+    )
+}
+
+#[allow(unused_macros)]
+macro do_not_use_safe_print($($t:tt)*) {
+    std::compile_error!("Don't use `safe_print` or `safe_println` here, use `println_info` instead")
+}
+
+// This import blocks the use of panicking `print` and `println` in all the code
+// below. Please use `safe_print` and `safe_println` to avoid ICE when
+// encountering an I/O error during print.
+#[allow(unused_imports)]
+use {do_not_use_print as print, do_not_use_print as println};
+
+pub mod args;
+pub mod pretty;
+#[macro_use]
+mod print;
+mod session_diagnostics;
+#[cfg(all(unix, any(target_env = "gnu", target_os = "macos")))]
+mod signal_handler;
+
+#[cfg(not(all(unix, any(target_env = "gnu", target_os = "macos"))))]
+mod signal_handler {
+    /// On platforms which don't support our signal handler's requirements,
+    /// simply use the default signal handler provided by std.
+    pub(super) fn install() {}
+}
+
+use crate::session_diagnostics::{
+    RLinkEmptyVersionNumber, RLinkEncodingVersionMismatch, RLinkRustcVersionMismatch,
+    RLinkWrongFileType, RlinkNotAFile, RlinkUnableToRead,
+};
+
+rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
+
+pub static DEFAULT_LOCALE_RESOURCES: &[&str] = &[
+    // tidy-alphabetical-start
+    crate::DEFAULT_LOCALE_RESOURCE,
+    rustc_ast_lowering::DEFAULT_LOCALE_RESOURCE,
+    rustc_ast_passes::DEFAULT_LOCALE_RESOURCE,
+    rustc_attr::DEFAULT_LOCALE_RESOURCE,
+    rustc_borrowck::DEFAULT_LOCALE_RESOURCE,
+    rustc_builtin_macros::DEFAULT_LOCALE_RESOURCE,
+    rustc_codegen_ssa::DEFAULT_LOCALE_RESOURCE,
+    rustc_const_eval::DEFAULT_LOCALE_RESOURCE,
+    rustc_errors::DEFAULT_LOCALE_RESOURCE,
+    rustc_expand::DEFAULT_LOCALE_RESOURCE,
+    rustc_hir_analysis::DEFAULT_LOCALE_RESOURCE,
+    rustc_hir_typeck::DEFAULT_LOCALE_RESOURCE,
+    rustc_incremental::DEFAULT_LOCALE_RESOURCE,
+    rustc_infer::DEFAULT_LOCALE_RESOURCE,
+    rustc_interface::DEFAULT_LOCALE_RESOURCE,
+    rustc_lint::DEFAULT_LOCALE_RESOURCE,
+    rustc_metadata::DEFAULT_LOCALE_RESOURCE,
+    rustc_middle::DEFAULT_LOCALE_RESOURCE,
+    rustc_mir_build::DEFAULT_LOCALE_RESOURCE,
+    rustc_mir_dataflow::DEFAULT_LOCALE_RESOURCE,
+    rustc_mir_transform::DEFAULT_LOCALE_RESOURCE,
+    rustc_monomorphize::DEFAULT_LOCALE_RESOURCE,
+    rustc_parse::DEFAULT_LOCALE_RESOURCE,
+    rustc_passes::DEFAULT_LOCALE_RESOURCE,
+    rustc_pattern_analysis::DEFAULT_LOCALE_RESOURCE,
+    rustc_privacy::DEFAULT_LOCALE_RESOURCE,
+    rustc_query_system::DEFAULT_LOCALE_RESOURCE,
+    rustc_resolve::DEFAULT_LOCALE_RESOURCE,
+    rustc_session::DEFAULT_LOCALE_RESOURCE,
+    rustc_trait_selection::DEFAULT_LOCALE_RESOURCE,
+    rustc_ty_utils::DEFAULT_LOCALE_RESOURCE,
+    // tidy-alphabetical-end
+];
+
+/// Exit status code used for successful compilation and help output.
+pub const EXIT_SUCCESS: i32 = 0;
+
+/// Exit status code used for compilation failures and invalid flags.
+pub const EXIT_FAILURE: i32 = 1;
+
+pub const DEFAULT_BUG_REPORT_URL: &str = "https://github.com/rust-lang/rust/issues/new\
+    ?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md";
+
+pub trait Callbacks {
+    /// Called before creating the compiler instance
+    fn config(&mut self, _config: &mut interface::Config) {}
+    /// Called after parsing the crate root. Submodules are not yet parsed when
+    /// this callback is called. Return value instructs the compiler whether to
+    /// continue the compilation afterwards (defaults to `Compilation::Continue`)
+    fn after_crate_root_parsing<'tcx>(
+        &mut self,
+        _compiler: &interface::Compiler,
+        _queries: &'tcx Queries<'tcx>,
+    ) -> Compilation {
+        Compilation::Continue
+    }
+    /// Called after expansion. Return value instructs the compiler whether to
+    /// continue the compilation afterwards (defaults to `Compilation::Continue`)
+    fn after_expansion<'tcx>(
+        &mut self,
+        _compiler: &interface::Compiler,
+        _queries: &'tcx Queries<'tcx>,
+    ) -> Compilation {
+        Compilation::Continue
+    }
+    /// Called after analysis. Return value instructs the compiler whether to
+    /// continue the compilation afterwards (defaults to `Compilation::Continue`)
+    fn after_analysis<'tcx>(
+        &mut self,
+        _compiler: &interface::Compiler,
+        _queries: &'tcx Queries<'tcx>,
+    ) -> Compilation {
+        Compilation::Continue
+    }
+}
+
+#[derive(Default)]
+pub struct TimePassesCallbacks {
+    time_passes: Option<TimePassesFormat>,
+}
+
+impl Callbacks for TimePassesCallbacks {
+    // JUSTIFICATION: the session doesn't exist at this point.
+    #[allow(rustc::bad_opt_access)]
+    fn config(&mut self, config: &mut interface::Config) {
+        // If a --print=... option has been given, we don't print the "total"
+        // time because it will mess up the --print output. See #64339.
+        //
+        self.time_passes = (config.opts.prints.is_empty() && config.opts.unstable_opts.time_passes)
+            .then(|| config.opts.unstable_opts.time_passes_format);
+        config.opts.trimmed_def_paths = true;
+    }
+}
+
+pub fn diagnostics_registry() -> Registry {
+    Registry::new(rustc_errors::codes::DIAGNOSTICS)
+}
+
+/// This is the primary entry point for rustc.
+pub struct RunCompiler<'a, 'b> {
+    at_args: &'a [String],
+    callbacks: &'b mut (dyn Callbacks + Send),
+    file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
+    make_codegen_backend:
+        Option<Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>>,
+    using_internal_features: Arc<std::sync::atomic::AtomicBool>,
+}
+
+impl<'a, 'b> RunCompiler<'a, 'b> {
+    pub fn new(at_args: &'a [String], callbacks: &'b mut (dyn Callbacks + Send)) -> Self {
+        Self {
+            at_args,
+            callbacks,
+            file_loader: None,
+            make_codegen_backend: None,
+            using_internal_features: Arc::default(),
+        }
+    }
+
+    /// Set a custom codegen backend.
+    ///
+    /// Has no uses within this repository, but is used by bjorn3 for "the
+    /// hotswapping branch of cg_clif" for "setting the codegen backend from a
+    /// custom driver where the custom codegen backend has arbitrary data."
+    /// (See #102759.)
+    pub fn set_make_codegen_backend(
+        &mut self,
+        make_codegen_backend: Option<
+            Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>,
+        >,
+    ) -> &mut Self {
+        self.make_codegen_backend = make_codegen_backend;
+        self
+    }
+
+    /// Load files from sources other than the file system.
+    ///
+    /// Has no uses within this repository, but may be used in the future by
+    /// bjorn3 for "hooking rust-analyzer's VFS into rustc at some point for
+    /// running rustc without having to save". (See #102759.)
+    pub fn set_file_loader(
+        &mut self,
+        file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
+    ) -> &mut Self {
+        self.file_loader = file_loader;
+        self
+    }
+
+    /// Set the session-global flag that checks whether internal features have been used,
+    /// suppressing the message about submitting an issue in ICEs when enabled.
+    #[must_use]
+    pub fn set_using_internal_features(mut self, using_internal_features: Arc<AtomicBool>) -> Self {
+        self.using_internal_features = using_internal_features;
+        self
+    }
+
+    /// Parse args and run the compiler.
+    pub fn run(self) -> interface::Result<()> {
+        run_compiler(
+            self.at_args,
+            self.callbacks,
+            self.file_loader,
+            self.make_codegen_backend,
+            self.using_internal_features,
+        )
+    }
+}
+
+fn run_compiler(
+    at_args: &[String],
+    callbacks: &mut (dyn Callbacks + Send),
+    file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
+    make_codegen_backend: Option<
+        Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>,
+    >,
+    using_internal_features: Arc<std::sync::atomic::AtomicBool>,
+) -> interface::Result<()> {
+    let mut default_early_dcx = EarlyDiagCtxt::new(ErrorOutputType::default());
+
+    // Throw away the first argument, the name of the binary.
+    // In case of at_args being empty, as might be the case by
+    // passing empty argument array to execve under some platforms,
+    // just use an empty slice.
+    //
+    // This situation was possible before due to arg_expand_all being
+    // called before removing the argument, enabling a crash by calling
+    // the compiler with @empty_file as argv[0] and no more arguments.
+    let at_args = at_args.get(1..).unwrap_or_default();
+
+    let args = args::arg_expand_all(&default_early_dcx, at_args)?;
+
+    let Some(matches) = handle_options(&default_early_dcx, &args) else { return Ok(()) };
+
+    let sopts = config::build_session_options(&mut default_early_dcx, &matches);
+
+    if let Some(ref code) = matches.opt_str("explain") {
+        handle_explain(&default_early_dcx, diagnostics_registry(), code, sopts.color);
+        return Ok(());
+    }
+
+    let (odir, ofile) = make_output(&matches);
+    let mut config = interface::Config {
+        opts: sopts,
+        crate_cfg: matches.opt_strs("cfg"),
+        crate_check_cfg: matches.opt_strs("check-cfg"),
+        input: Input::File(PathBuf::new()),
+        output_file: ofile,
+        output_dir: odir,
+        ice_file: ice_path().clone(),
+        file_loader,
+        locale_resources: DEFAULT_LOCALE_RESOURCES,
+        lint_caps: Default::default(),
+        psess_created: None,
+        hash_untracked_state: None,
+        register_lints: None,
+        override_queries: None,
+        make_codegen_backend,
+        registry: diagnostics_registry(),
+        using_internal_features,
+        expanded_args: args,
+    };
+
+    let has_input = match make_input(&default_early_dcx, &matches.free) {
+        Err(reported) => return Err(reported),
+        Ok(Some(input)) => {
+            config.input = input;
+            true // has input: normal compilation
+        }
+        Ok(None) => match matches.free.len() {
+            0 => false, // no input: we will exit early
+            1 => panic!("make_input should have provided valid inputs"),
+            _ => default_early_dcx.early_fatal(format!(
+                "multiple input filenames provided (first two filenames are `{}` and `{}`)",
+                matches.free[0], matches.free[1],
+            )),
+        },
+    };
+
+    drop(default_early_dcx);
+
+    callbacks.config(&mut config);
+
+    interface::run_compiler(config, |compiler| {
+        let sess = &compiler.sess;
+        let codegen_backend = &*compiler.codegen_backend;
+
+        // This is used for early exits unrelated to errors. E.g. when just
+        // printing some information without compiling, or exiting immediately
+        // after parsing, etc.
+        let early_exit = || {
+            if let Some(guar) = sess.dcx().has_errors() { Err(guar) } else { Ok(()) }
+        };
+
+        // This implements `-Whelp`. It should be handled very early, like
+        // `--help`/`-Zhelp`/`-Chelp`. This is the earliest it can run, because
+        // it must happen after lints are registered, during session creation.
+        if sess.opts.describe_lints {
+            describe_lints(sess);
+            return early_exit();
+        }
+
+        let early_dcx = EarlyDiagCtxt::new(sess.opts.error_format);
+
+        if print_crate_info(&early_dcx, codegen_backend, sess, has_input) == Compilation::Stop {
+            return early_exit();
+        }
+
+        if !has_input {
+            early_dcx.early_fatal("no input filename given"); // this is fatal
+        }
+
+        if !sess.opts.unstable_opts.ls.is_empty() {
+            list_metadata(&early_dcx, sess, &*codegen_backend.metadata_loader());
+            return early_exit();
+        }
+
+        if sess.opts.unstable_opts.link_only {
+            process_rlink(sess, compiler);
+            return early_exit();
+        }
+
+        let linker = compiler.enter(|queries| {
+            let early_exit = || early_exit().map(|_| None);
+            queries.parse()?;
+
+            if let Some(ppm) = &sess.opts.pretty {
+                if ppm.needs_ast_map() {
+                    queries.global_ctxt()?.enter(|tcx| {
+                        tcx.ensure().early_lint_checks(());
+                        pretty::print(sess, *ppm, pretty::PrintExtra::NeedsAstMap { tcx });
+                        Ok(())
+                    })?;
+
+                    queries.write_dep_info()?;
+                } else {
+                    let krate = queries.parse()?;
+                    pretty::print(
+                        sess,
+                        *ppm,
+                        pretty::PrintExtra::AfterParsing { krate: &*krate.borrow() },
+                    );
+                }
+                trace!("finished pretty-printing");
+                return early_exit();
+            }
+
+            if callbacks.after_crate_root_parsing(compiler, queries) == Compilation::Stop {
+                return early_exit();
+            }
+
+            if sess.opts.unstable_opts.parse_only || sess.opts.unstable_opts.show_span.is_some() {
+                return early_exit();
+            }
+
+            // Make sure name resolution and macro expansion is run.
+            queries.global_ctxt()?.enter(|tcx| tcx.resolver_for_lowering());
+
+            if callbacks.after_expansion(compiler, queries) == Compilation::Stop {
+                return early_exit();
+            }
+
+            queries.write_dep_info()?;
+
+            if sess.opts.output_types.contains_key(&OutputType::DepInfo)
+                && sess.opts.output_types.len() == 1
+            {
+                return early_exit();
+            }
+
+            if sess.opts.unstable_opts.no_analysis {
+                return early_exit();
+            }
+
+            queries.global_ctxt()?.enter(|tcx| tcx.analysis(()))?;
+
+            if callbacks.after_analysis(compiler, queries) == Compilation::Stop {
+                return early_exit();
+            }
+
+            let linker = queries.codegen_and_build_linker()?;
+
+            // This must run after monomorphization so that all generic types
+            // have been instantiated.
+            if sess.opts.unstable_opts.print_type_sizes {
+                sess.code_stats.print_type_sizes();
+            }
+
+            if sess.opts.unstable_opts.print_vtable_sizes {
+                let crate_name = queries.global_ctxt()?.enter(|tcx| tcx.crate_name(LOCAL_CRATE));
+
+                sess.code_stats.print_vtable_sizes(crate_name);
+            }
+
+            Ok(Some(linker))
+        })?;
+
+        // Linking is done outside the `compiler.enter()` so that the
+        // `GlobalCtxt` within `Queries` can be freed as early as possible.
+        if let Some(linker) = linker {
+            let _timer = sess.timer("link");
+            linker.link(sess, codegen_backend)?
+        }
+
+        if sess.opts.unstable_opts.print_fuel.is_some() {
+            eprintln!(
+                "Fuel used by {}: {}",
+                sess.opts.unstable_opts.print_fuel.as_ref().unwrap(),
+                sess.print_fuel.load(Ordering::SeqCst)
+            );
+        }
+
+        Ok(())
+    })
+}
+
+// Extract output directory and file from matches.
+fn make_output(matches: &getopts::Matches) -> (Option<PathBuf>, Option<OutFileName>) {
+    let odir = matches.opt_str("out-dir").map(|o| PathBuf::from(&o));
+    let ofile = matches.opt_str("o").map(|o| match o.as_str() {
+        "-" => OutFileName::Stdout,
+        path => OutFileName::Real(PathBuf::from(path)),
+    });
+    (odir, ofile)
+}
+
+// Extract input (string or file and optional path) from matches.
+fn make_input(
+    early_dcx: &EarlyDiagCtxt,
+    free_matches: &[String],
+) -> Result<Option<Input>, ErrorGuaranteed> {
+    if free_matches.len() == 1 {
+        let ifile = &free_matches[0];
+        if ifile == "-" {
+            let mut src = String::new();
+            if io::stdin().read_to_string(&mut src).is_err() {
+                // Immediately stop compilation if there was an issue reading
+                // the input (for example if the input stream is not UTF-8).
+                let reported = early_dcx
+                    .early_err("couldn't read from stdin, as it did not contain valid UTF-8");
+                return Err(reported);
+            }
+            if let Ok(path) = env::var("UNSTABLE_RUSTDOC_TEST_PATH") {
+                let line = env::var("UNSTABLE_RUSTDOC_TEST_LINE").expect(
+                    "when UNSTABLE_RUSTDOC_TEST_PATH is set \
+                                    UNSTABLE_RUSTDOC_TEST_LINE also needs to be set",
+                );
+                let line = isize::from_str_radix(&line, 10)
+                    .expect("UNSTABLE_RUSTDOC_TEST_LINE needs to be an number");
+                let file_name = FileName::doc_test_source_code(PathBuf::from(path), line);
+                Ok(Some(Input::Str { name: file_name, input: src }))
+            } else {
+                Ok(Some(Input::Str { name: FileName::anon_source_code(&src), input: src }))
+            }
+        } else {
+            Ok(Some(Input::File(PathBuf::from(ifile))))
+        }
+    } else {
+        Ok(None)
+    }
+}
+
+/// Whether to stop or continue compilation.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum Compilation {
+    Stop,
+    Continue,
+}
+
+fn handle_explain(early_dcx: &EarlyDiagCtxt, registry: Registry, code: &str, color: ColorConfig) {
+    // Allow "E0123" or "0123" form.
+    let upper_cased_code = code.to_ascii_uppercase();
+    let start = if upper_cased_code.starts_with('E') { 1 } else { 0 };
+    if let Ok(code) = upper_cased_code[start..].parse::<u32>()
+        && let Ok(description) = registry.try_find_description(ErrCode::from_u32(code))
+    {
+        let mut is_in_code_block = false;
+        let mut text = String::new();
+        // Slice off the leading newline and print.
+        for line in description.lines() {
+            let indent_level =
+                line.find(|c: char| !c.is_whitespace()).unwrap_or_else(|| line.len());
+            let dedented_line = &line[indent_level..];
+            if dedented_line.starts_with("```") {
+                is_in_code_block = !is_in_code_block;
+                text.push_str(&line[..(indent_level + 3)]);
+            } else if is_in_code_block && dedented_line.starts_with("# ") {
+                continue;
+            } else {
+                text.push_str(line);
+            }
+            text.push('\n');
+        }
+        if io::stdout().is_terminal() {
+            show_md_content_with_pager(&text, color);
+        } else {
+            safe_print!("{text}");
+        }
+    } else {
+        early_dcx.early_fatal(format!("{code} is not a valid error code"));
+    }
+}
+
+/// If color is always or auto, print formatted & colorized markdown. If color is never or
+/// if formatted printing fails, print the raw text.
+///
+/// Prefers a pager, falls back standard print
+fn show_md_content_with_pager(content: &str, color: ColorConfig) {
+    let mut fallback_to_println = false;
+    let pager_name = env::var_os("PAGER").unwrap_or_else(|| {
+        if cfg!(windows) { OsString::from("more.com") } else { OsString::from("less") }
+    });
+
+    let mut cmd = Command::new(&pager_name);
+    // FIXME: find if other pagers accept color options
+    let mut print_formatted = if pager_name == "less" {
+        cmd.arg("-r");
+        true
+    } else {
+        ["bat", "catbat", "delta"].iter().any(|v| *v == pager_name)
+    };
+
+    if color == ColorConfig::Never {
+        print_formatted = false;
+    } else if color == ColorConfig::Always {
+        print_formatted = true;
+    }
+
+    let mdstream = markdown::MdStream::parse_str(content);
+    let bufwtr = markdown::create_stdout_bufwtr();
+    let mut mdbuf = bufwtr.buffer();
+    if mdstream.write_termcolor_buf(&mut mdbuf).is_err() {
+        print_formatted = false;
+    }
+
+    if let Ok(mut pager) = cmd.stdin(Stdio::piped()).spawn() {
+        if let Some(pipe) = pager.stdin.as_mut() {
+            let res = if print_formatted {
+                pipe.write_all(mdbuf.as_slice())
+            } else {
+                pipe.write_all(content.as_bytes())
+            };
+
+            if res.is_err() {
+                fallback_to_println = true;
+            }
+        }
+
+        if pager.wait().is_err() {
+            fallback_to_println = true;
+        }
+    } else {
+        fallback_to_println = true;
+    }
+
+    // If pager fails for whatever reason, we should still print the content
+    // to standard output
+    if fallback_to_println {
+        let fmt_success = match color {
+            ColorConfig::Auto => io::stdout().is_terminal() && bufwtr.print(&mdbuf).is_ok(),
+            ColorConfig::Always => bufwtr.print(&mdbuf).is_ok(),
+            ColorConfig::Never => false,
+        };
+
+        if !fmt_success {
+            safe_print!("{content}");
+        }
+    }
+}
+
+fn process_rlink(sess: &Session, compiler: &interface::Compiler) {
+    assert!(sess.opts.unstable_opts.link_only);
+    let dcx = sess.dcx();
+    if let Input::File(file) = &sess.io.input {
+        let rlink_data = fs::read(file).unwrap_or_else(|err| {
+            dcx.emit_fatal(RlinkUnableToRead { err });
+        });
+        let (codegen_results, outputs) = match CodegenResults::deserialize_rlink(sess, rlink_data) {
+            Ok((codegen, outputs)) => (codegen, outputs),
+            Err(err) => {
+                match err {
+                    CodegenErrors::WrongFileType => dcx.emit_fatal(RLinkWrongFileType),
+                    CodegenErrors::EmptyVersionNumber => dcx.emit_fatal(RLinkEmptyVersionNumber),
+                    CodegenErrors::EncodingVersionMismatch { version_array, rlink_version } => sess
+                        .dcx()
+                        .emit_fatal(RLinkEncodingVersionMismatch { version_array, rlink_version }),
+                    CodegenErrors::RustcVersionMismatch { rustc_version } => {
+                        dcx.emit_fatal(RLinkRustcVersionMismatch {
+                            rustc_version,
+                            current_version: sess.cfg_version,
+                        })
+                    }
+                };
+            }
+        };
+        if compiler.codegen_backend.link(sess, codegen_results, &outputs).is_err() {
+            FatalError.raise();
+        }
+    } else {
+        dcx.emit_fatal(RlinkNotAFile {});
+    }
+}
+
+fn list_metadata(early_dcx: &EarlyDiagCtxt, sess: &Session, metadata_loader: &dyn MetadataLoader) {
+    match sess.io.input {
+        Input::File(ref ifile) => {
+            let path = &(*ifile);
+            let mut v = Vec::new();
+            locator::list_file_metadata(
+                &sess.target,
+                path,
+                metadata_loader,
+                &mut v,
+                &sess.opts.unstable_opts.ls,
+                sess.cfg_version,
+            )
+            .unwrap();
+            safe_println!("{}", String::from_utf8(v).unwrap());
+        }
+        Input::Str { .. } => {
+            early_dcx.early_fatal("cannot list metadata for stdin");
+        }
+    }
+}
+
+fn print_crate_info(
+    early_dcx: &EarlyDiagCtxt,
+    codegen_backend: &dyn CodegenBackend,
+    sess: &Session,
+    parse_attrs: bool,
+) -> Compilation {
+    use rustc_session::config::PrintKind::*;
+
+    // This import prevents the following code from using the printing macros
+    // used by the rest of the module. Within this function, we only write to
+    // the output specified by `sess.io.output_file`.
+    #[allow(unused_imports)]
+    use {do_not_use_safe_print as safe_print, do_not_use_safe_print as safe_println};
+
+    // NativeStaticLibs and LinkArgs are special - printed during linking
+    // (empty iterator returns true)
+    if sess.opts.prints.iter().all(|p| p.kind == NativeStaticLibs || p.kind == LinkArgs) {
+        return Compilation::Continue;
+    }
+
+    let attrs = if parse_attrs {
+        let result = parse_crate_attrs(sess);
+        match result {
+            Ok(attrs) => Some(attrs),
+            Err(parse_error) => {
+                parse_error.emit();
+                return Compilation::Stop;
+            }
+        }
+    } else {
+        None
+    };
+
+    for req in &sess.opts.prints {
+        let mut crate_info = String::new();
+        macro println_info($($arg:tt)*) {
+            crate_info.write_fmt(format_args!("{}\n", format_args!($($arg)*))).unwrap()
+        }
+
+        match req.kind {
+            TargetList => {
+                let mut targets = rustc_target::spec::TARGETS.to_vec();
+                targets.sort_unstable();
+                println_info!("{}", targets.join("\n"));
+            }
+            Sysroot => println_info!("{}", sess.sysroot.display()),
+            TargetLibdir => println_info!("{}", sess.target_tlib_path.dir.display()),
+            TargetSpec => {
+                println_info!("{}", serde_json::to_string_pretty(&sess.target.to_json()).unwrap());
+            }
+            AllTargetSpecs => {
+                let mut targets = BTreeMap::new();
+                for name in rustc_target::spec::TARGETS {
+                    let triple = TargetTriple::from_triple(name);
+                    let target = Target::expect_builtin(&triple);
+                    targets.insert(name, target.to_json());
+                }
+                println_info!("{}", serde_json::to_string_pretty(&targets).unwrap());
+            }
+            FileNames => {
+                let Some(attrs) = attrs.as_ref() else {
+                    // no crate attributes, print out an error and exit
+                    return Compilation::Continue;
+                };
+                let t_outputs = rustc_interface::util::build_output_filenames(attrs, sess);
+                let id = rustc_session::output::find_crate_name(sess, attrs);
+                let crate_types = collect_crate_types(sess, attrs);
+                for &style in &crate_types {
+                    let fname =
+                        rustc_session::output::filename_for_input(sess, style, id, &t_outputs);
+                    println_info!("{}", fname.as_path().file_name().unwrap().to_string_lossy());
+                }
+            }
+            CrateName => {
+                let Some(attrs) = attrs.as_ref() else {
+                    // no crate attributes, print out an error and exit
+                    return Compilation::Continue;
+                };
+                let id = rustc_session::output::find_crate_name(sess, attrs);
+                println_info!("{id}");
+            }
+            Cfg => {
+                let mut cfgs = sess
+                    .psess
+                    .config
+                    .iter()
+                    .filter_map(|&(name, value)| {
+                        // Note that crt-static is a specially recognized cfg
+                        // directive that's printed out here as part of
+                        // rust-lang/rust#37406, but in general the
+                        // `target_feature` cfg is gated under
+                        // rust-lang/rust#29717. For now this is just
+                        // specifically allowing the crt-static cfg and that's
+                        // it, this is intended to get into Cargo and then go
+                        // through to build scripts.
+                        if (name != sym::target_feature || value != Some(sym::crt_dash_static))
+                            && !sess.is_nightly_build()
+                            && find_gated_cfg(|cfg_sym| cfg_sym == name).is_some()
+                        {
+                            return None;
+                        }
+
+                        if let Some(value) = value {
+                            Some(format!("{name}=\"{value}\""))
+                        } else {
+                            Some(name.to_string())
+                        }
+                    })
+                    .collect::<Vec<String>>();
+
+                cfgs.sort();
+                for cfg in cfgs {
+                    println_info!("{cfg}");
+                }
+            }
+            CallingConventions => {
+                let mut calling_conventions = rustc_target::spec::abi::all_names();
+                calling_conventions.sort_unstable();
+                println_info!("{}", calling_conventions.join("\n"));
+            }
+            RelocationModels
+            | CodeModels
+            | TlsModels
+            | TargetCPUs
+            | StackProtectorStrategies
+            | TargetFeatures => {
+                codegen_backend.print(req, &mut crate_info, sess);
+            }
+            // Any output here interferes with Cargo's parsing of other printed output
+            NativeStaticLibs => {}
+            LinkArgs => {}
+            SplitDebuginfo => {
+                use rustc_target::spec::SplitDebuginfo::{Off, Packed, Unpacked};
+
+                for split in &[Off, Packed, Unpacked] {
+                    if sess.target.options.supported_split_debuginfo.contains(split) {
+                        println_info!("{split}");
+                    }
+                }
+            }
+            DeploymentTarget => {
+                use rustc_target::spec::current_apple_deployment_target;
+
+                if sess.target.is_like_osx {
+                    let (major, minor) = current_apple_deployment_target(&sess.target)
+                        .expect("unknown Apple target OS");
+                    println_info!("deployment_target={}", format!("{major}.{minor}"))
+                } else {
+                    early_dcx
+                        .early_fatal("only Apple targets currently support deployment version info")
+                }
+            }
+        }
+
+        req.out.overwrite(&crate_info, sess);
+    }
+    Compilation::Stop
+}
+
+/// Prints version information
+///
+/// NOTE: this is a macro to support drivers built at a different time than the main `rustc_driver` crate.
+pub macro version($early_dcx: expr, $binary: literal, $matches: expr) {
+    fn unw(x: Option<&str>) -> &str {
+        x.unwrap_or("unknown")
+    }
+    $crate::version_at_macro_invocation(
+        $early_dcx,
+        $binary,
+        $matches,
+        unw(option_env!("CFG_VERSION")),
+        unw(option_env!("CFG_VER_HASH")),
+        unw(option_env!("CFG_VER_DATE")),
+        unw(option_env!("CFG_RELEASE")),
+    )
+}
+
+#[doc(hidden)] // use the macro instead
+pub fn version_at_macro_invocation(
+    early_dcx: &EarlyDiagCtxt,
+    binary: &str,
+    matches: &getopts::Matches,
+    version: &str,
+    commit_hash: &str,
+    commit_date: &str,
+    release: &str,
+) {
+    let verbose = matches.opt_present("verbose");
+
+    safe_println!("{binary} {version}");
+
+    if verbose {
+        safe_println!("binary: {binary}");
+        safe_println!("commit-hash: {commit_hash}");
+        safe_println!("commit-date: {commit_date}");
+        safe_println!("host: {}", config::host_triple());
+        safe_println!("release: {release}");
+
+        let debug_flags = matches.opt_strs("Z");
+        let backend_name = debug_flags.iter().find_map(|x| x.strip_prefix("codegen-backend="));
+        let opts = config::Options::default();
+        let sysroot = filesearch::materialize_sysroot(opts.maybe_sysroot.clone());
+        let target = config::build_target_config(early_dcx, &opts, &sysroot);
+
+        get_codegen_backend(early_dcx, &sysroot, backend_name, &target).print_version();
+    }
+}
+
+fn usage(verbose: bool, include_unstable_options: bool, nightly_build: bool) {
+    let groups = if verbose { config::rustc_optgroups() } else { config::rustc_short_optgroups() };
+    let mut options = getopts::Options::new();
+    for option in groups.iter().filter(|x| include_unstable_options || x.is_stable()) {
+        (option.apply)(&mut options);
+    }
+    let message = "Usage: rustc [OPTIONS] INPUT";
+    let nightly_help = if nightly_build {
+        "\n    -Z help             Print unstable compiler options"
+    } else {
+        ""
+    };
+    let verbose_help = if verbose {
+        ""
+    } else {
+        "\n    --help -v           Print the full set of options rustc accepts"
+    };
+    let at_path = if verbose {
+        "    @path               Read newline separated options from `path`\n"
+    } else {
+        ""
+    };
+    safe_println!(
+        "{options}{at_path}\nAdditional help:
+    -C help             Print codegen options
+    -W help             \
+              Print 'lint' options and default settings{nightly}{verbose}\n",
+        options = options.usage(message),
+        at_path = at_path,
+        nightly = nightly_help,
+        verbose = verbose_help
+    );
+}
+
+fn print_wall_help() {
+    safe_println!(
+        "
+The flag `-Wall` does not exist in `rustc`. Most useful lints are enabled by
+default. Use `rustc -W help` to see all available lints. It's more common to put
+warning settings in the crate root using `#![warn(LINT_NAME)]` instead of using
+the command line flag directly.
+"
+    );
+}
+
+/// Write to stdout lint command options, together with a list of all available lints
+pub fn describe_lints(sess: &Session) {
+    safe_println!(
+        "
+Available lint options:
+    -W <foo>           Warn about <foo>
+    -A <foo>           Allow <foo>
+    -D <foo>           Deny <foo>
+    -F <foo>           Forbid <foo> (deny <foo> and all attempts to override)
+
+"
+    );
+
+    fn sort_lints(sess: &Session, mut lints: Vec<&'static Lint>) -> Vec<&'static Lint> {
+        // The sort doesn't case-fold but it's doubtful we care.
+        lints.sort_by_cached_key(|x: &&Lint| (x.default_level(sess.edition()), x.name));
+        lints
+    }
+
+    fn sort_lint_groups(
+        lints: Vec<(&'static str, Vec<LintId>, bool)>,
+    ) -> Vec<(&'static str, Vec<LintId>)> {
+        let mut lints: Vec<_> = lints.into_iter().map(|(x, y, _)| (x, y)).collect();
+        lints.sort_by_key(|l| l.0);
+        lints
+    }
+
+    let lint_store = unerased_lint_store(sess);
+    let (loaded, builtin): (Vec<_>, _) =
+        lint_store.get_lints().iter().cloned().partition(|&lint| lint.is_externally_loaded);
+    let loaded = sort_lints(sess, loaded);
+    let builtin = sort_lints(sess, builtin);
+
+    let (loaded_groups, builtin_groups): (Vec<_>, _) =
+        lint_store.get_lint_groups().partition(|&(.., p)| p);
+    let loaded_groups = sort_lint_groups(loaded_groups);
+    let builtin_groups = sort_lint_groups(builtin_groups);
+
+    let max_name_len =
+        loaded.iter().chain(&builtin).map(|&s| s.name.chars().count()).max().unwrap_or(0);
+    let padded = |x: &str| {
+        let mut s = " ".repeat(max_name_len - x.chars().count());
+        s.push_str(x);
+        s
+    };
+
+    safe_println!("Lint checks provided by rustc:\n");
+
+    let print_lints = |lints: Vec<&Lint>| {
+        safe_println!("    {}  {:7.7}  {}", padded("name"), "default", "meaning");
+        safe_println!("    {}  {:7.7}  {}", padded("----"), "-------", "-------");
+        for lint in lints {
+            let name = lint.name_lower().replace('_', "-");
+            safe_println!(
+                "    {}  {:7.7}  {}",
+                padded(&name),
+                lint.default_level(sess.edition()).as_str(),
+                lint.desc
+            );
+        }
+        safe_println!("\n");
+    };
+
+    print_lints(builtin);
+
+    let max_name_len = max(
+        "warnings".len(),
+        loaded_groups
+            .iter()
+            .chain(&builtin_groups)
+            .map(|&(s, _)| s.chars().count())
+            .max()
+            .unwrap_or(0),
+    );
+
+    let padded = |x: &str| {
+        let mut s = " ".repeat(max_name_len - x.chars().count());
+        s.push_str(x);
+        s
+    };
+
+    safe_println!("Lint groups provided by rustc:\n");
+
+    let print_lint_groups = |lints: Vec<(&'static str, Vec<LintId>)>, all_warnings| {
+        safe_println!("    {}  sub-lints", padded("name"));
+        safe_println!("    {}  ---------", padded("----"));
+
+        if all_warnings {
+            safe_println!("    {}  all lints that are set to issue warnings", padded("warnings"));
+        }
+
+        for (name, to) in lints {
+            let name = name.to_lowercase().replace('_', "-");
+            let desc = to
+                .into_iter()
+                .map(|x| x.to_string().replace('_', "-"))
+                .collect::<Vec<String>>()
+                .join(", ");
+            safe_println!("    {}  {}", padded(&name), desc);
+        }
+        safe_println!("\n");
+    };
+
+    print_lint_groups(builtin_groups, true);
+
+    match (sess.registered_lints, loaded.len(), loaded_groups.len()) {
+        (false, 0, _) | (false, _, 0) => {
+            safe_println!("Lint tools like Clippy can load additional lints and lint groups.");
+        }
+        (false, ..) => panic!("didn't load additional lints but got them anyway!"),
+        (true, 0, 0) => {
+            safe_println!("This crate does not load any additional lints or lint groups.")
+        }
+        (true, l, g) => {
+            if l > 0 {
+                safe_println!("Lint checks loaded by this crate:\n");
+                print_lints(loaded);
+            }
+            if g > 0 {
+                safe_println!("Lint groups loaded by this crate:\n");
+                print_lint_groups(loaded_groups, false);
+            }
+        }
+    }
+}
+
+/// Show help for flag categories shared between rustdoc and rustc.
+///
+/// Returns whether a help option was printed.
+pub fn describe_flag_categories(early_dcx: &EarlyDiagCtxt, matches: &Matches) -> bool {
+    // Handle the special case of -Wall.
+    let wall = matches.opt_strs("W");
+    if wall.iter().any(|x| *x == "all") {
+        print_wall_help();
+        rustc_errors::FatalError.raise();
+    }
+
+    // Don't handle -W help here, because we might first load additional lints.
+    let debug_flags = matches.opt_strs("Z");
+    if debug_flags.iter().any(|x| *x == "help") {
+        describe_debug_flags();
+        return true;
+    }
+
+    let cg_flags = matches.opt_strs("C");
+    if cg_flags.iter().any(|x| *x == "help") {
+        describe_codegen_flags();
+        return true;
+    }
+
+    if cg_flags.iter().any(|x| *x == "no-stack-check") {
+        early_dcx.early_warn("the --no-stack-check flag is deprecated and does nothing");
+    }
+
+    if cg_flags.iter().any(|x| *x == "passes=list") {
+        let backend_name = debug_flags.iter().find_map(|x| x.strip_prefix("codegen-backend="));
+
+        let opts = config::Options::default();
+        let sysroot = filesearch::materialize_sysroot(opts.maybe_sysroot.clone());
+        let target = config::build_target_config(early_dcx, &opts, &sysroot);
+
+        get_codegen_backend(early_dcx, &sysroot, backend_name, &target).print_passes();
+        return true;
+    }
+
+    false
+}
+
+fn describe_debug_flags() {
+    safe_println!("\nAvailable options:\n");
+    print_flag_list("-Z", config::Z_OPTIONS);
+}
+
+fn describe_codegen_flags() {
+    safe_println!("\nAvailable codegen options:\n");
+    print_flag_list("-C", config::CG_OPTIONS);
+}
+
+fn print_flag_list<T>(
+    cmdline_opt: &str,
+    flag_list: &[(&'static str, T, &'static str, &'static str)],
+) {
+    let max_len = flag_list.iter().map(|&(name, _, _, _)| name.chars().count()).max().unwrap_or(0);
+
+    for &(name, _, _, desc) in flag_list {
+        safe_println!(
+            "    {} {:>width$}=val -- {}",
+            cmdline_opt,
+            name.replace('_', "-"),
+            desc,
+            width = max_len
+        );
+    }
+}
+
+/// Process command line options. Emits messages as appropriate. If compilation
+/// should continue, returns a getopts::Matches object parsed from args,
+/// otherwise returns `None`.
+///
+/// The compiler's handling of options is a little complicated as it ties into
+/// our stability story. The current intention of each compiler option is to
+/// have one of two modes:
+///
+/// 1. An option is stable and can be used everywhere.
+/// 2. An option is unstable, and can only be used on nightly.
+///
+/// Like unstable library and language features, however, unstable options have
+/// always required a form of "opt in" to indicate that you're using them. This
+/// provides the easy ability to scan a code base to check to see if anything
+/// unstable is being used. Currently, this "opt in" is the `-Z` "zed" flag.
+///
+/// All options behind `-Z` are considered unstable by default. Other top-level
+/// options can also be considered unstable, and they were unlocked through the
+/// `-Z unstable-options` flag. Note that `-Z` remains to be the root of
+/// instability in both cases, though.
+///
+/// So with all that in mind, the comments below have some more detail about the
+/// contortions done here to get things to work out correctly.
+///
+/// This does not need to be `pub` for rustc itself, but @chaosite needs it to
+/// be public when using rustc as a library, see
+/// <https://github.com/rust-lang/rust/commit/2b4c33817a5aaecabf4c6598d41e190080ec119e>
+pub fn handle_options(early_dcx: &EarlyDiagCtxt, args: &[String]) -> Option<getopts::Matches> {
+    if args.is_empty() {
+        // user did not write `-v` nor `-Z unstable-options`, so do not
+        // include that extra information.
+        let nightly_build =
+            rustc_feature::UnstableFeatures::from_environment(None).is_nightly_build();
+        usage(false, false, nightly_build);
+        return None;
+    }
+
+    // Parse with *all* options defined in the compiler, we don't worry about
+    // option stability here we just want to parse as much as possible.
+    let mut options = getopts::Options::new();
+    for option in config::rustc_optgroups() {
+        (option.apply)(&mut options);
+    }
+    let matches = options.parse(args).unwrap_or_else(|e| {
+        let msg = match e {
+            getopts::Fail::UnrecognizedOption(ref opt) => CG_OPTIONS
+                .iter()
+                .map(|&(name, ..)| ('C', name))
+                .chain(Z_OPTIONS.iter().map(|&(name, ..)| ('Z', name)))
+                .find(|&(_, name)| *opt == name.replace('_', "-"))
+                .map(|(flag, _)| format!("{e}. Did you mean `-{flag} {opt}`?")),
+            _ => None,
+        };
+        early_dcx.early_fatal(msg.unwrap_or_else(|| e.to_string()));
+    });
+
+    // For all options we just parsed, we check a few aspects:
+    //
+    // * If the option is stable, we're all good
+    // * If the option wasn't passed, we're all good
+    // * If `-Z unstable-options` wasn't passed (and we're not a -Z option
+    //   ourselves), then we require the `-Z unstable-options` flag to unlock
+    //   this option that was passed.
+    // * If we're a nightly compiler, then unstable options are now unlocked, so
+    //   we're good to go.
+    // * Otherwise, if we're an unstable option then we generate an error
+    //   (unstable option being used on stable)
+    nightly_options::check_nightly_options(early_dcx, &matches, &config::rustc_optgroups());
+
+    if matches.opt_present("h") || matches.opt_present("help") {
+        // Only show unstable options in --help if we accept unstable options.
+        let unstable_enabled = nightly_options::is_unstable_enabled(&matches);
+        let nightly_build = nightly_options::match_is_nightly_build(&matches);
+        usage(matches.opt_present("verbose"), unstable_enabled, nightly_build);
+        return None;
+    }
+
+    if describe_flag_categories(early_dcx, &matches) {
+        return None;
+    }
+
+    if matches.opt_present("version") {
+        version!(early_dcx, "rustc", &matches);
+        return None;
+    }
+
+    Some(matches)
+}
+
+fn parse_crate_attrs<'a>(sess: &'a Session) -> PResult<'a, ast::AttrVec> {
+    match &sess.io.input {
+        Input::File(ifile) => rustc_parse::parse_crate_attrs_from_file(ifile, &sess.psess),
+        Input::Str { name, input } => {
+            rustc_parse::parse_crate_attrs_from_source_str(name.clone(), input.clone(), &sess.psess)
+        }
+    }
+}
+
+/// Runs a closure and catches unwinds triggered by fatal errors.
+///
+/// The compiler currently unwinds with a special sentinel value to abort
+/// compilation on fatal errors. This function catches that sentinel and turns
+/// the panic into a `Result` instead.
+pub fn catch_fatal_errors<F: FnOnce() -> R, R>(f: F) -> Result<R, FatalError> {
+    catch_unwind(panic::AssertUnwindSafe(f)).map_err(|value| {
+        if value.is::<rustc_errors::FatalErrorMarker>() {
+            FatalError
+        } else {
+            panic::resume_unwind(value);
+        }
+    })
+}
+
+/// Variant of `catch_fatal_errors` for the `interface::Result` return type
+/// that also computes the exit code.
+pub fn catch_with_exit_code(f: impl FnOnce() -> interface::Result<()>) -> i32 {
+    match catch_fatal_errors(f) {
+        Ok(Ok(())) => EXIT_SUCCESS,
+        _ => EXIT_FAILURE,
+    }
+}
+
+static ICE_PATH: OnceLock<Option<PathBuf>> = OnceLock::new();
+
+fn ice_path() -> &'static Option<PathBuf> {
+    ICE_PATH.get_or_init(|| {
+        if !rustc_feature::UnstableFeatures::from_environment(None).is_nightly_build() {
+            return None;
+        }
+        if let Some(s) = std::env::var_os("RUST_BACKTRACE")
+            && s == "0"
+        {
+            return None;
+        }
+        let mut path = match std::env::var_os("RUSTC_ICE") {
+            Some(s) => {
+                if s == "0" {
+                    // Explicitly opting out of writing ICEs to disk.
+                    return None;
+                }
+                PathBuf::from(s)
+            }
+            None => std::env::current_dir().unwrap_or_default(),
+        };
+        let now: OffsetDateTime = SystemTime::now().into();
+        let file_now = now
+            .format(
+                // Don't use a standard datetime format because Windows doesn't support `:` in paths
+                &time::format_description::parse("[year]-[month]-[day]T[hour]_[minute]_[second]")
+                    .unwrap(),
+            )
+            .unwrap_or_default();
+        let pid = std::process::id();
+        path.push(format!("rustc-ice-{file_now}-{pid}.txt"));
+        Some(path)
+    })
+}
+
+/// Installs a panic hook that will print the ICE message on unexpected panics.
+///
+/// The hook is intended to be useable even by external tools. You can pass a custom
+/// `bug_report_url`, or report arbitrary info in `extra_info`. Note that `extra_info` is called in
+/// a context where *the thread is currently panicking*, so it must not panic or the process will
+/// abort.
+///
+/// If you have no extra info to report, pass the empty closure `|_| ()` as the argument to
+/// extra_info.
+///
+/// Returns a flag that can be set to disable the note for submitting a bug. This can be passed to
+/// [`RunCompiler::set_using_internal_features`] to let macro expansion set it when encountering
+/// internal features.
+///
+/// A custom rustc driver can skip calling this to set up a custom ICE hook.
+pub fn install_ice_hook(
+    bug_report_url: &'static str,
+    extra_info: fn(&DiagCtxt),
+) -> Arc<AtomicBool> {
+    // If the user has not explicitly overridden "RUST_BACKTRACE", then produce
+    // full backtraces. When a compiler ICE happens, we want to gather
+    // as much information as possible to present in the issue opened
+    // by the user. Compiler developers and other rustc users can
+    // opt in to less-verbose backtraces by manually setting "RUST_BACKTRACE"
+    // (e.g. `RUST_BACKTRACE=1`)
+    if env::var_os("RUST_BACKTRACE").is_none() {
+        panic::set_backtrace_style(panic::BacktraceStyle::Full);
+    }
+
+    let using_internal_features = Arc::new(std::sync::atomic::AtomicBool::default());
+    let using_internal_features_hook = using_internal_features.clone();
+    panic::update_hook(Box::new(
+        move |default_hook: &(dyn Fn(&PanicInfo<'_>) + Send + Sync + 'static),
+              info: &PanicInfo<'_>| {
+            // Lock stderr to prevent interleaving of concurrent panics.
+            let _guard = io::stderr().lock();
+
+            // If the error was caused by a broken pipe then this is not a bug.
+            // Write the error and return immediately. See #98700.
+            #[cfg(windows)]
+            if let Some(msg) = info.payload().downcast_ref::<String>() {
+                if msg.starts_with("failed printing to stdout: ") && msg.ends_with("(os error 232)")
+                {
+                    // the error code is already going to be reported when the panic unwinds up the stack
+                    let early_dcx = EarlyDiagCtxt::new(ErrorOutputType::default());
+                    let _ = early_dcx.early_err(msg.clone());
+                    return;
+                }
+            };
+
+            // Invoke the default handler, which prints the actual panic message and optionally a backtrace
+            // Don't do this for delayed bugs, which already emit their own more useful backtrace.
+            if !info.payload().is::<rustc_errors::DelayedBugPanic>() {
+                default_hook(info);
+                // Separate the output with an empty line
+                eprintln!();
+
+                if let Some(ice_path) = ice_path()
+                    && let Ok(mut out) = File::options().create(true).append(true).open(&ice_path)
+                {
+                    // The current implementation always returns `Some`.
+                    let location = info.location().unwrap();
+                    let msg = match info.payload().downcast_ref::<&'static str>() {
+                        Some(s) => *s,
+                        None => match info.payload().downcast_ref::<String>() {
+                            Some(s) => &s[..],
+                            None => "Box<dyn Any>",
+                        },
+                    };
+                    let thread = std::thread::current();
+                    let name = thread.name().unwrap_or("<unnamed>");
+                    let _ = write!(
+                        &mut out,
+                        "thread '{name}' panicked at {location}:\n\
+                        {msg}\n\
+                        stack backtrace:\n\
+                        {:#}",
+                        std::backtrace::Backtrace::force_capture()
+                    );
+                }
+            }
+
+            // Print the ICE message
+            report_ice(info, bug_report_url, extra_info, &using_internal_features_hook);
+        },
+    ));
+
+    using_internal_features
+}
+
+/// Prints the ICE message, including query stack, but without backtrace.
+///
+/// The message will point the user at `bug_report_url` to report the ICE.
+///
+/// When `install_ice_hook` is called, this function will be called as the panic
+/// hook.
+fn report_ice(
+    info: &panic::PanicInfo<'_>,
+    bug_report_url: &str,
+    extra_info: fn(&DiagCtxt),
+    using_internal_features: &AtomicBool,
+) {
+    let fallback_bundle =
+        rustc_errors::fallback_fluent_bundle(crate::DEFAULT_LOCALE_RESOURCES.to_vec(), false);
+    let emitter = Box::new(rustc_errors::emitter::HumanEmitter::new(
+        stderr_destination(rustc_errors::ColorConfig::Auto),
+        fallback_bundle,
+    ));
+    let dcx = rustc_errors::DiagCtxt::new(emitter);
+
+    // a .span_bug or .bug call has already printed what
+    // it wants to print.
+    if !info.payload().is::<rustc_errors::ExplicitBug>()
+        && !info.payload().is::<rustc_errors::DelayedBugPanic>()
+    {
+        dcx.emit_err(session_diagnostics::Ice);
+    }
+
+    if using_internal_features.load(std::sync::atomic::Ordering::Relaxed) {
+        dcx.emit_note(session_diagnostics::IceBugReportInternalFeature);
+    } else {
+        dcx.emit_note(session_diagnostics::IceBugReport { bug_report_url });
+
+        // Only emit update nightly hint for users on nightly builds.
+        if rustc_feature::UnstableFeatures::from_environment(None).is_nightly_build() {
+            dcx.emit_note(session_diagnostics::UpdateNightlyNote);
+        }
+    }
+
+    let version = util::version_str!().unwrap_or("unknown_version");
+    let triple = config::host_triple();
+
+    static FIRST_PANIC: AtomicBool = AtomicBool::new(true);
+
+    let file = if let Some(path) = ice_path() {
+        // Create the ICE dump target file.
+        match crate::fs::File::options().create(true).append(true).open(&path) {
+            Ok(mut file) => {
+                dcx.emit_note(session_diagnostics::IcePath { path: path.clone() });
+                if FIRST_PANIC.swap(false, Ordering::SeqCst) {
+                    let _ = write!(file, "\n\nrustc version: {version}\nplatform: {triple}");
+                }
+                Some(file)
+            }
+            Err(err) => {
+                // The path ICE couldn't be written to disk, provide feedback to the user as to why.
+                dcx.emit_warn(session_diagnostics::IcePathError {
+                    path: path.clone(),
+                    error: err.to_string(),
+                    env_var: std::env::var_os("RUSTC_ICE")
+                        .map(PathBuf::from)
+                        .map(|env_var| session_diagnostics::IcePathErrorEnv { env_var }),
+                });
+                dcx.emit_note(session_diagnostics::IceVersion { version, triple });
+                None
+            }
+        }
+    } else {
+        dcx.emit_note(session_diagnostics::IceVersion { version, triple });
+        None
+    };
+
+    if let Some((flags, excluded_cargo_defaults)) = rustc_session::utils::extra_compiler_flags() {
+        dcx.emit_note(session_diagnostics::IceFlags { flags: flags.join(" ") });
+        if excluded_cargo_defaults {
+            dcx.emit_note(session_diagnostics::IceExcludeCargoDefaults);
+        }
+    }
+
+    // If backtraces are enabled, also print the query stack
+    let backtrace = env::var_os("RUST_BACKTRACE").is_some_and(|x| &x != "0");
+
+    let num_frames = if backtrace { None } else { Some(2) };
+
+    interface::try_print_query_stack(&dcx, num_frames, file);
+
+    // We don't trust this callback not to panic itself, so run it at the end after we're sure we've
+    // printed all the relevant info.
+    extra_info(&dcx);
+
+    #[cfg(windows)]
+    if env::var("RUSTC_BREAK_ON_ICE").is_ok() {
+        // Trigger a debugger if we crashed during bootstrap
+        unsafe { windows::Win32::System::Diagnostics::Debug::DebugBreak() };
+    }
+}
+
+/// This allows tools to enable rust logging without having to magically match rustc's
+/// tracing crate version.
+pub fn init_rustc_env_logger(early_dcx: &EarlyDiagCtxt) {
+    init_logger(early_dcx, rustc_log::LoggerConfig::from_env("RUSTC_LOG"));
+}
+
+/// This allows tools to enable rust logging without having to magically match rustc's
+/// tracing crate version. In contrast to `init_rustc_env_logger` it allows you to choose
+/// the values directly rather than having to set an environment variable.
+pub fn init_logger(early_dcx: &EarlyDiagCtxt, cfg: rustc_log::LoggerConfig) {
+    if let Err(error) = rustc_log::init_logger(cfg) {
+        early_dcx.early_fatal(error.to_string());
+    }
+}
+
+/// Install our usual `ctrlc` handler, which sets [`rustc_const_eval::CTRL_C_RECEIVED`].
+/// Making this handler optional lets tools can install a different handler, if they wish.
+pub fn install_ctrlc_handler() {
+    #[cfg(not(target_family = "wasm"))]
+    ctrlc::set_handler(move || {
+        // Indicate that we have been signaled to stop. If we were already signaled, exit
+        // immediately. In our interpreter loop we try to consult this value often, but if for
+        // whatever reason we don't get to that check or the cleanup we do upon finding that
+        // this bool has become true takes a long time, the exit here will promptly exit the
+        // process on the second Ctrl-C.
+        if CTRL_C_RECEIVED.swap(true, Ordering::Relaxed) {
+            std::process::exit(1);
+        }
+    })
+    .expect("Unable to install ctrlc handler");
+}
+
+pub fn main() -> ! {
+    let start_time = Instant::now();
+    let start_rss = get_resident_set_size();
+
+    let early_dcx = EarlyDiagCtxt::new(ErrorOutputType::default());
+
+    init_rustc_env_logger(&early_dcx);
+    signal_handler::install();
+    let mut callbacks = TimePassesCallbacks::default();
+    let using_internal_features = install_ice_hook(DEFAULT_BUG_REPORT_URL, |_| ());
+    install_ctrlc_handler();
+
+    let exit_code = catch_with_exit_code(|| {
+        RunCompiler::new(&args::raw_args(&early_dcx)?, &mut callbacks)
+            .set_using_internal_features(using_internal_features)
+            .run()
+    });
+
+    if let Some(format) = callbacks.time_passes {
+        let end_rss = get_resident_set_size();
+        print_time_passes_entry("total", start_time.elapsed(), start_rss, end_rss, format);
+    }
+
+    process::exit(exit_code)
+}
diff --git a/compiler/rustc_driver_impl/src/pretty.rs b/compiler/rustc_driver_impl/src/pretty.rs
new file mode 100644
index 00000000000..fe426b8111c
--- /dev/null
+++ b/compiler/rustc_driver_impl/src/pretty.rs
@@ -0,0 +1,348 @@
+//! The various pretty-printing routines.
+
+use rustc_ast as ast;
+use rustc_ast_pretty::pprust as pprust_ast;
+use rustc_errors::FatalError;
+use rustc_hir as hir;
+use rustc_hir_pretty as pprust_hir;
+use rustc_middle::bug;
+use rustc_middle::mir::{write_mir_graphviz, write_mir_pretty};
+use rustc_middle::ty::{self, TyCtxt};
+use rustc_session::config::{OutFileName, PpHirMode, PpMode, PpSourceMode};
+use rustc_session::Session;
+use rustc_smir::rustc_internal::pretty::write_smir_pretty;
+use rustc_span::symbol::Ident;
+use rustc_span::FileName;
+use std::cell::Cell;
+use std::fmt::Write;
+use tracing::debug;
+
+pub use self::PpMode::*;
+pub use self::PpSourceMode::*;
+
+struct AstNoAnn;
+
+impl pprust_ast::PpAnn for AstNoAnn {}
+
+struct AstIdentifiedAnn;
+
+impl pprust_ast::PpAnn for AstIdentifiedAnn {
+    fn pre(&self, s: &mut pprust_ast::State<'_>, node: pprust_ast::AnnNode<'_>) {
+        if let pprust_ast::AnnNode::Expr(_) = node {
+            s.popen();
+        }
+    }
+
+    fn post(&self, s: &mut pprust_ast::State<'_>, node: pprust_ast::AnnNode<'_>) {
+        match node {
+            pprust_ast::AnnNode::Crate(_)
+            | pprust_ast::AnnNode::Ident(_)
+            | pprust_ast::AnnNode::Name(_) => {}
+
+            pprust_ast::AnnNode::Item(item) => {
+                s.s.space();
+                s.synth_comment(item.id.to_string())
+            }
+            pprust_ast::AnnNode::SubItem(id) => {
+                s.s.space();
+                s.synth_comment(id.to_string())
+            }
+            pprust_ast::AnnNode::Block(blk) => {
+                s.s.space();
+                s.synth_comment(format!("block {}", blk.id))
+            }
+            pprust_ast::AnnNode::Expr(expr) => {
+                s.s.space();
+                s.synth_comment(expr.id.to_string());
+                s.pclose()
+            }
+            pprust_ast::AnnNode::Pat(pat) => {
+                s.s.space();
+                s.synth_comment(format!("pat {}", pat.id));
+            }
+        }
+    }
+}
+
+struct HirIdentifiedAnn<'tcx> {
+    tcx: TyCtxt<'tcx>,
+}
+
+impl<'tcx> pprust_hir::PpAnn for HirIdentifiedAnn<'tcx> {
+    fn nested(&self, state: &mut pprust_hir::State<'_>, nested: pprust_hir::Nested) {
+        pprust_hir::PpAnn::nested(
+            &(&self.tcx.hir() as &dyn hir::intravisit::Map<'_>),
+            state,
+            nested,
+        )
+    }
+
+    fn pre(&self, s: &mut pprust_hir::State<'_>, node: pprust_hir::AnnNode<'_>) {
+        if let pprust_hir::AnnNode::Expr(_) = node {
+            s.popen();
+        }
+    }
+
+    fn post(&self, s: &mut pprust_hir::State<'_>, node: pprust_hir::AnnNode<'_>) {
+        match node {
+            pprust_hir::AnnNode::Name(_) => {}
+            pprust_hir::AnnNode::Item(item) => {
+                s.s.space();
+                s.synth_comment(format!("hir_id: {}", item.hir_id()));
+            }
+            pprust_hir::AnnNode::SubItem(id) => {
+                s.s.space();
+                s.synth_comment(id.to_string());
+            }
+            pprust_hir::AnnNode::Block(blk) => {
+                s.s.space();
+                s.synth_comment(format!("block hir_id: {}", blk.hir_id));
+            }
+            pprust_hir::AnnNode::Expr(expr) => {
+                s.s.space();
+                s.synth_comment(format!("expr hir_id: {}", expr.hir_id));
+                s.pclose();
+            }
+            pprust_hir::AnnNode::Pat(pat) => {
+                s.s.space();
+                s.synth_comment(format!("pat hir_id: {}", pat.hir_id));
+            }
+            pprust_hir::AnnNode::Arm(arm) => {
+                s.s.space();
+                s.synth_comment(format!("arm hir_id: {}", arm.hir_id));
+            }
+        }
+    }
+}
+
+struct AstHygieneAnn<'a> {
+    sess: &'a Session,
+}
+
+impl<'a> pprust_ast::PpAnn for AstHygieneAnn<'a> {
+    fn post(&self, s: &mut pprust_ast::State<'_>, node: pprust_ast::AnnNode<'_>) {
+        match node {
+            pprust_ast::AnnNode::Ident(&Ident { name, span }) => {
+                s.s.space();
+                s.synth_comment(format!("{}{:?}", name.as_u32(), span.ctxt()))
+            }
+            pprust_ast::AnnNode::Name(&name) => {
+                s.s.space();
+                s.synth_comment(name.as_u32().to_string())
+            }
+            pprust_ast::AnnNode::Crate(_) => {
+                s.s.hardbreak();
+                let verbose = self.sess.verbose_internals();
+                s.synth_comment(rustc_span::hygiene::debug_hygiene_data(verbose));
+                s.s.hardbreak_if_not_bol();
+            }
+            _ => {}
+        }
+    }
+}
+
+struct HirTypedAnn<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    maybe_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
+}
+
+impl<'tcx> pprust_hir::PpAnn for HirTypedAnn<'tcx> {
+    fn nested(&self, state: &mut pprust_hir::State<'_>, nested: pprust_hir::Nested) {
+        let old_maybe_typeck_results = self.maybe_typeck_results.get();
+        if let pprust_hir::Nested::Body(id) = nested {
+            self.maybe_typeck_results.set(Some(self.tcx.typeck_body(id)));
+        }
+        let pp_ann = &(&self.tcx.hir() as &dyn hir::intravisit::Map<'_>);
+        pprust_hir::PpAnn::nested(pp_ann, state, nested);
+        self.maybe_typeck_results.set(old_maybe_typeck_results);
+    }
+
+    fn pre(&self, s: &mut pprust_hir::State<'_>, node: pprust_hir::AnnNode<'_>) {
+        if let pprust_hir::AnnNode::Expr(_) = node {
+            s.popen();
+        }
+    }
+
+    fn post(&self, s: &mut pprust_hir::State<'_>, node: pprust_hir::AnnNode<'_>) {
+        if let pprust_hir::AnnNode::Expr(expr) = node {
+            let typeck_results = self.maybe_typeck_results.get().or_else(|| {
+                self.tcx
+                    .hir()
+                    .maybe_body_owned_by(expr.hir_id.owner.def_id)
+                    .map(|body_id| self.tcx.typeck_body(body_id))
+            });
+
+            if let Some(typeck_results) = typeck_results {
+                s.s.space();
+                s.s.word("as");
+                s.s.space();
+                s.s.word(typeck_results.expr_ty(expr).to_string());
+            }
+
+            s.pclose();
+        }
+    }
+}
+
+fn get_source(sess: &Session) -> (String, FileName) {
+    let src_name = sess.io.input.source_name();
+    let src = String::clone(
+        sess.source_map()
+            .get_source_file(&src_name)
+            .expect("get_source_file")
+            .src
+            .as_ref()
+            .expect("src"),
+    );
+    (src, src_name)
+}
+
+fn write_or_print(out: &str, sess: &Session) {
+    sess.io.output_file.as_ref().unwrap_or(&OutFileName::Stdout).overwrite(out, sess);
+}
+
+// Extra data for pretty-printing, the form of which depends on what kind of
+// pretty-printing we are doing.
+pub enum PrintExtra<'tcx> {
+    AfterParsing { krate: &'tcx ast::Crate },
+    NeedsAstMap { tcx: TyCtxt<'tcx> },
+}
+
+impl<'tcx> PrintExtra<'tcx> {
+    fn with_krate<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&ast::Crate) -> R,
+    {
+        match self {
+            PrintExtra::AfterParsing { krate, .. } => f(krate),
+            PrintExtra::NeedsAstMap { tcx } => f(&tcx.resolver_for_lowering().borrow().1),
+        }
+    }
+
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        match self {
+            PrintExtra::AfterParsing { .. } => bug!("PrintExtra::tcx"),
+            PrintExtra::NeedsAstMap { tcx } => *tcx,
+        }
+    }
+}
+
+pub fn print<'tcx>(sess: &Session, ppm: PpMode, ex: PrintExtra<'tcx>) {
+    if ppm.needs_analysis() {
+        if ex.tcx().analysis(()).is_err() {
+            FatalError.raise();
+        }
+    }
+
+    let (src, src_name) = get_source(sess);
+
+    let out = match ppm {
+        Source(s) => {
+            debug!("pretty printing source code {:?}", s);
+            let annotation: Box<dyn pprust_ast::PpAnn> = match s {
+                Normal => Box::new(AstNoAnn),
+                Expanded => Box::new(AstNoAnn),
+                Identified => Box::new(AstIdentifiedAnn),
+                ExpandedIdentified => Box::new(AstIdentifiedAnn),
+                ExpandedHygiene => Box::new(AstHygieneAnn { sess }),
+            };
+            let psess = &sess.psess;
+            let is_expanded = ppm.needs_ast_map();
+            ex.with_krate(|krate| {
+                pprust_ast::print_crate(
+                    sess.source_map(),
+                    krate,
+                    src_name,
+                    src,
+                    &*annotation,
+                    is_expanded,
+                    psess.edition,
+                    &sess.psess.attr_id_generator,
+                )
+            })
+        }
+        AstTree => {
+            debug!("pretty printing AST tree");
+            ex.with_krate(|krate| format!("{krate:#?}"))
+        }
+        AstTreeExpanded => {
+            debug!("pretty-printing expanded AST");
+            format!("{:#?}", ex.tcx().resolver_for_lowering().borrow().1)
+        }
+        Hir(s) => {
+            debug!("pretty printing HIR {:?}", s);
+            let tcx = ex.tcx();
+            let f = |annotation: &dyn pprust_hir::PpAnn| {
+                let sm = sess.source_map();
+                let hir_map = tcx.hir();
+                let attrs = |id| hir_map.attrs(id);
+                pprust_hir::print_crate(
+                    sm,
+                    hir_map.root_module(),
+                    src_name,
+                    src,
+                    &attrs,
+                    annotation,
+                )
+            };
+            match s {
+                PpHirMode::Normal => f(&tcx),
+                PpHirMode::Identified => {
+                    let annotation = HirIdentifiedAnn { tcx };
+                    f(&annotation)
+                }
+                PpHirMode::Typed => {
+                    let annotation = HirTypedAnn { tcx, maybe_typeck_results: Cell::new(None) };
+                    tcx.dep_graph.with_ignore(|| f(&annotation))
+                }
+            }
+        }
+        HirTree => {
+            debug!("pretty printing HIR tree");
+            format!("{:#?}", ex.tcx().hir().krate())
+        }
+        Mir => {
+            let mut out = Vec::new();
+            write_mir_pretty(ex.tcx(), None, &mut out).unwrap();
+            String::from_utf8(out).unwrap()
+        }
+        MirCFG => {
+            let mut out = Vec::new();
+            write_mir_graphviz(ex.tcx(), None, &mut out).unwrap();
+            String::from_utf8(out).unwrap()
+        }
+        StableMir => {
+            let mut out = Vec::new();
+            write_smir_pretty(ex.tcx(), &mut out).unwrap();
+            String::from_utf8(out).unwrap()
+        }
+        ThirTree => {
+            let tcx = ex.tcx();
+            let mut out = String::new();
+            rustc_hir_analysis::check_crate(tcx);
+            if tcx.dcx().has_errors().is_some() {
+                FatalError.raise();
+            }
+            debug!("pretty printing THIR tree");
+            for did in tcx.hir().body_owners() {
+                let _ = writeln!(out, "{:?}:\n{}\n", did, tcx.thir_tree(did));
+            }
+            out
+        }
+        ThirFlat => {
+            let tcx = ex.tcx();
+            let mut out = String::new();
+            rustc_hir_analysis::check_crate(tcx);
+            if tcx.dcx().has_errors().is_some() {
+                FatalError.raise();
+            }
+            debug!("pretty printing THIR flat");
+            for did in tcx.hir().body_owners() {
+                let _ = writeln!(out, "{:?}:\n{}\n", did, tcx.thir_flat(did));
+            }
+            out
+        }
+    };
+
+    write_or_print(&out, sess);
+}
diff --git a/compiler/rustc_driver_impl/src/print.rs b/compiler/rustc_driver_impl/src/print.rs
new file mode 100644
index 00000000000..70de55320f7
--- /dev/null
+++ b/compiler/rustc_driver_impl/src/print.rs
@@ -0,0 +1,20 @@
+use std::fmt;
+use std::io::{self, Write as _};
+
+macro_rules! safe_print {
+    ($($arg:tt)*) => {{
+        $crate::print::print(std::format_args!($($arg)*));
+    }};
+}
+
+macro_rules! safe_println {
+    ($($arg:tt)*) => {
+        safe_print!("{}\n", std::format_args!($($arg)*))
+    };
+}
+
+pub(crate) fn print(args: fmt::Arguments<'_>) {
+    if let Err(_) = io::stdout().write_fmt(args) {
+        rustc_errors::FatalError.raise();
+    }
+}
diff --git a/compiler/rustc_driver_impl/src/session_diagnostics.rs b/compiler/rustc_driver_impl/src/session_diagnostics.rs
new file mode 100644
index 00000000000..1a9683e840a
--- /dev/null
+++ b/compiler/rustc_driver_impl/src/session_diagnostics.rs
@@ -0,0 +1,89 @@
+use rustc_macros::{Diagnostic, Subdiagnostic};
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_rlink_unable_to_read)]
+pub(crate) struct RlinkUnableToRead {
+    pub err: std::io::Error,
+}
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_rlink_wrong_file_type)]
+pub(crate) struct RLinkWrongFileType;
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_rlink_empty_version_number)]
+pub(crate) struct RLinkEmptyVersionNumber;
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_rlink_encoding_version_mismatch)]
+pub(crate) struct RLinkEncodingVersionMismatch {
+    pub version_array: String,
+    pub rlink_version: u32,
+}
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_rlink_rustc_version_mismatch)]
+pub(crate) struct RLinkRustcVersionMismatch<'a> {
+    pub rustc_version: String,
+    pub current_version: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_rlink_no_a_file)]
+pub(crate) struct RlinkNotAFile;
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice)]
+pub(crate) struct Ice;
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice_bug_report)]
+pub(crate) struct IceBugReport<'a> {
+    pub bug_report_url: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice_bug_report_update_note)]
+pub(crate) struct UpdateNightlyNote;
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice_bug_report_internal_feature)]
+pub(crate) struct IceBugReportInternalFeature;
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice_version)]
+pub(crate) struct IceVersion<'a> {
+    pub version: &'a str,
+    pub triple: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice_path)]
+pub(crate) struct IcePath {
+    pub path: std::path::PathBuf,
+}
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice_path_error)]
+pub(crate) struct IcePathError {
+    pub path: std::path::PathBuf,
+    pub error: String,
+    #[subdiagnostic]
+    pub env_var: Option<IcePathErrorEnv>,
+}
+
+#[derive(Subdiagnostic)]
+#[note(driver_impl_ice_path_error_env)]
+pub(crate) struct IcePathErrorEnv {
+    pub env_var: std::path::PathBuf,
+}
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice_flags)]
+pub(crate) struct IceFlags {
+    pub flags: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(driver_impl_ice_exclude_cargo_defaults)]
+pub(crate) struct IceExcludeCargoDefaults;
diff --git a/compiler/rustc_driver_impl/src/signal_handler.rs b/compiler/rustc_driver_impl/src/signal_handler.rs
new file mode 100644
index 00000000000..441219eec90
--- /dev/null
+++ b/compiler/rustc_driver_impl/src/signal_handler.rs
@@ -0,0 +1,146 @@
+//! Signal handler for rustc
+//! Primarily used to extract a backtrace from stack overflow
+
+use rustc_interface::util::{DEFAULT_STACK_SIZE, STACK_SIZE};
+use std::alloc::{alloc, Layout};
+use std::{fmt, mem, ptr};
+
+extern "C" {
+    fn backtrace_symbols_fd(buffer: *const *mut libc::c_void, size: libc::c_int, fd: libc::c_int);
+}
+
+fn backtrace_stderr(buffer: &[*mut libc::c_void]) {
+    let size = buffer.len().try_into().unwrap_or_default();
+    unsafe { backtrace_symbols_fd(buffer.as_ptr(), size, libc::STDERR_FILENO) };
+}
+
+/// Unbuffered, unsynchronized writer to stderr.
+///
+/// Only acceptable because everything will end soon anyways.
+struct RawStderr(());
+
+impl fmt::Write for RawStderr {
+    fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
+        let ret = unsafe { libc::write(libc::STDERR_FILENO, s.as_ptr().cast(), s.len()) };
+        if ret == -1 { Err(fmt::Error) } else { Ok(()) }
+    }
+}
+
+/// We don't really care how many bytes we actually get out. SIGSEGV comes for our head.
+/// Splash stderr with letters of our own blood to warn our friends about the monster.
+macro raw_errln($tokens:tt) {
+    let _ = ::core::fmt::Write::write_fmt(&mut RawStderr(()), format_args!($tokens));
+    let _ = ::core::fmt::Write::write_char(&mut RawStderr(()), '\n');
+}
+
+/// Signal handler installed for SIGSEGV
+extern "C" fn print_stack_trace(_: libc::c_int) {
+    const MAX_FRAMES: usize = 256;
+    // Reserve data segment so we don't have to malloc in a signal handler, which might fail
+    // in incredibly undesirable and unexpected ways due to e.g. the allocator deadlocking
+    static mut STACK_TRACE: [*mut libc::c_void; MAX_FRAMES] = [ptr::null_mut(); MAX_FRAMES];
+    let stack = unsafe {
+        // Collect return addresses
+        let depth = libc::backtrace(STACK_TRACE.as_mut_ptr(), MAX_FRAMES as i32);
+        if depth == 0 {
+            return;
+        }
+        &STACK_TRACE.as_slice()[0..(depth as _)]
+    };
+
+    // Just a stack trace is cryptic. Explain what we're doing.
+    raw_errln!("error: rustc interrupted by SIGSEGV, printing backtrace\n");
+    let mut written = 1;
+    let mut consumed = 0;
+    // Begin elaborating return addrs into symbols and writing them directly to stderr
+    // Most backtraces are stack overflow, most stack overflows are from recursion
+    // Check for cycles before writing 250 lines of the same ~5 symbols
+    let cycled = |(runner, walker)| runner == walker;
+    let mut cyclic = false;
+    if let Some(period) = stack.iter().skip(1).step_by(2).zip(stack).position(cycled) {
+        let period = period.saturating_add(1); // avoid "what if wrapped?" branches
+        let Some(offset) = stack.iter().skip(period).zip(stack).position(cycled) else {
+            // impossible.
+            return;
+        };
+
+        // Count matching trace slices, else we could miscount "biphasic cycles"
+        // with the same period + loop entry but a different inner loop
+        let next_cycle = stack[offset..].chunks_exact(period).skip(1);
+        let cycles = 1 + next_cycle
+            .zip(stack[offset..].chunks_exact(period))
+            .filter(|(next, prev)| next == prev)
+            .count();
+        backtrace_stderr(&stack[..offset]);
+        written += offset;
+        consumed += offset;
+        if cycles > 1 {
+            raw_errln!("\n### cycle encountered after {offset} frames with period {period}");
+            backtrace_stderr(&stack[consumed..consumed + period]);
+            raw_errln!("### recursed {cycles} times\n");
+            written += period + 4;
+            consumed += period * cycles;
+            cyclic = true;
+        };
+    }
+    let rem = &stack[consumed..];
+    backtrace_stderr(rem);
+    raw_errln!("");
+    written += rem.len() + 1;
+
+    let random_depth = || 8 * 16; // chosen by random diceroll (2d20)
+    if cyclic || stack.len() > random_depth() {
+        // technically speculation, but assert it with confidence anyway.
+        // rustc only arrived in this signal handler because bad things happened
+        // and this message is for explaining it's not the programmer's fault
+        raw_errln!("note: rustc unexpectedly overflowed its stack! this is a bug");
+        written += 1;
+    }
+    if stack.len() == MAX_FRAMES {
+        raw_errln!("note: maximum backtrace depth reached, frames may have been lost");
+        written += 1;
+    }
+    raw_errln!("note: we would appreciate a report at https://github.com/rust-lang/rust");
+    // get the current stack size WITHOUT blocking and double it
+    let new_size = STACK_SIZE.get().copied().unwrap_or(DEFAULT_STACK_SIZE) * 2;
+    raw_errln!("help: you can increase rustc's stack size by setting RUST_MIN_STACK={new_size}");
+    written += 2;
+    if written > 24 {
+        // We probably just scrolled the earlier "we got SIGSEGV" message off the terminal
+        raw_errln!("note: backtrace dumped due to SIGSEGV! resuming signal");
+    };
+}
+
+/// When SIGSEGV is delivered to the process, print a stack trace and then exit.
+pub(super) fn install() {
+    unsafe {
+        let alt_stack_size: usize = min_sigstack_size() + 64 * 1024;
+        let mut alt_stack: libc::stack_t = mem::zeroed();
+        alt_stack.ss_sp = alloc(Layout::from_size_align(alt_stack_size, 1).unwrap()).cast();
+        alt_stack.ss_size = alt_stack_size;
+        libc::sigaltstack(&alt_stack, ptr::null_mut());
+
+        let mut sa: libc::sigaction = mem::zeroed();
+        sa.sa_sigaction = print_stack_trace as libc::sighandler_t;
+        sa.sa_flags = libc::SA_NODEFER | libc::SA_RESETHAND | libc::SA_ONSTACK;
+        libc::sigemptyset(&mut sa.sa_mask);
+        libc::sigaction(libc::SIGSEGV, &sa, ptr::null_mut());
+    }
+}
+
+/// Modern kernels on modern hardware can have dynamic signal stack sizes.
+#[cfg(any(target_os = "linux", target_os = "android"))]
+fn min_sigstack_size() -> usize {
+    const AT_MINSIGSTKSZ: core::ffi::c_ulong = 51;
+    let dynamic_sigstksz = unsafe { libc::getauxval(AT_MINSIGSTKSZ) };
+    // If getauxval couldn't find the entry, it returns 0,
+    // so take the higher of the "constant" and auxval.
+    // This transparently supports older kernels which don't provide AT_MINSIGSTKSZ
+    libc::MINSIGSTKSZ.max(dynamic_sigstksz as _)
+}
+
+/// Not all OS support hardware where this is needed.
+#[cfg(not(any(target_os = "linux", target_os = "android")))]
+fn min_sigstack_size() -> usize {
+    libc::MINSIGSTKSZ
+}