Merging upstream version 1.72.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

9 files changed, 712 insertions, 352 deletions

diff --git a/compiler/rustc_session/src/code_stats.rs b/compiler/rustc_session/src/code_stats.rs
index 0dfee92f4..cabe1c96b 100644
--- a/compiler/rustc_session/src/code_stats.rs
+++ b/compiler/rustc_session/src/code_stats.rs
@@ -1,5 +1,6 @@
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::Lock;
+use rustc_span::def_id::DefId;
 use rustc_span::Symbol;
 use rustc_target::abi::{Align, Size};
 use std::cmp;
@@ -65,9 +66,29 @@ pub struct TypeSizeInfo {
     pub variants: Vec<VariantInfo>,
 }
 
+pub struct VTableSizeInfo {
+    pub trait_name: String,
+
+    /// Number of entries in a vtable with the current algorithm
+    /// (i.e. with upcasting).
+    pub entries: usize,
+
+    /// Number of entries in a vtable, as-if we did not have trait upcasting.
+    pub entries_ignoring_upcasting: usize,
+
+    /// Number of entries in a vtable needed solely for upcasting
+    /// (i.e. `entries - entries_ignoring_upcasting`).
+    pub entries_for_upcasting: usize,
+
+    /// Cost of having upcasting in % relative to the number of entries without
+    /// upcasting (i.e. `entries_for_upcasting / entries_ignoring_upcasting * 100%`).
+    pub upcasting_cost_percent: f64,
+}
+
 #[derive(Default)]
 pub struct CodeStats {
     type_sizes: Lock<FxHashSet<TypeSizeInfo>>,
+    vtable_sizes: Lock<FxHashMap<DefId, VTableSizeInfo>>,
 }
 
 impl CodeStats {
@@ -101,6 +122,14 @@ impl CodeStats {
         self.type_sizes.borrow_mut().insert(info);
     }
 
+    pub fn record_vtable_size(&self, trait_did: DefId, trait_name: &str, info: VTableSizeInfo) {
+        let prev = self.vtable_sizes.lock().insert(trait_did, info);
+        assert!(
+            prev.is_none(),
+            "size of vtable for `{trait_name}` ({trait_did:?}) is already recorded"
+        );
+    }
+
     pub fn print_type_sizes(&self) {
         let type_sizes = self.type_sizes.borrow();
         let mut sorted: Vec<_> = type_sizes.iter().collect();
@@ -196,4 +225,33 @@ impl CodeStats {
             }
         }
     }
+
+    pub fn print_vtable_sizes(&self, crate_name: &str) {
+        let mut infos = std::mem::take(&mut *self.vtable_sizes.lock())
+            .into_iter()
+            .map(|(_did, stats)| stats)
+            .collect::<Vec<_>>();
+
+        // Primary sort: cost % in reverse order (from largest to smallest)
+        // Secondary sort: trait_name
+        infos.sort_by(|a, b| {
+            a.upcasting_cost_percent
+                .total_cmp(&b.upcasting_cost_percent)
+                .reverse()
+                .then_with(|| a.trait_name.cmp(&b.trait_name))
+        });
+
+        for VTableSizeInfo {
+            trait_name,
+            entries,
+            entries_ignoring_upcasting,
+            entries_for_upcasting,
+            upcasting_cost_percent,
+        } in infos
+        {
+            println!(
+                r#"print-vtable-sizes {{ "crate_name": "{crate_name}", "trait_name": "{trait_name}", "entries": "{entries}", "entries_ignoring_upcasting": "{entries_ignoring_upcasting}", "entries_for_upcasting": "{entries_for_upcasting}", "upcasting_cost_percent": "{upcasting_cost_percent}" }}"#
+            );
+        }
+    }
 }
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 6c8c8e484..f97cb3440 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -5,11 +5,10 @@ pub use crate::options::*;
 
 use crate::search_paths::SearchPath;
 use crate::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
-use crate::{early_error, early_warn, Session};
 use crate::{lint, HashStableContext};
+use crate::{EarlyErrorHandler, Session};
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-
 use rustc_data_structures::stable_hasher::{StableOrd, ToStableHashKey};
 use rustc_target::abi::Align;
 use rustc_target::spec::{PanicStrategy, SanitizerSet, SplitDebuginfo};
@@ -30,6 +29,7 @@ use std::collections::btree_map::{
     Iter as BTreeMapIter, Keys as BTreeMapKeysIter, Values as BTreeMapValuesIter,
 };
 use std::collections::{BTreeMap, BTreeSet};
+use std::ffi::OsStr;
 use std::fmt;
 use std::hash::Hash;
 use std::iter;
@@ -200,6 +200,128 @@ pub enum LinkerPluginLto {
     Disabled,
 }
 
+impl LinkerPluginLto {
+    pub fn enabled(&self) -> bool {
+        match *self {
+            LinkerPluginLto::LinkerPlugin(_) | LinkerPluginLto::LinkerPluginAuto => true,
+            LinkerPluginLto::Disabled => false,
+        }
+    }
+}
+
+/// The different values `-C link-self-contained` can take: a list of individually enabled or
+/// disabled components used during linking, coming from the rustc distribution, instead of being
+/// found somewhere on the host system.
+///
+/// They can be set in bulk via `-C link-self-contained=yes|y|on` or `-C
+/// link-self-contained=no|n|off`, and those boolean values are the historical defaults.
+///
+/// But each component is fine-grained, and can be unstably targeted, to use:
+/// - some CRT objects
+/// - the libc static library
+/// - libgcc/libunwind libraries
+/// - a linker we distribute
+/// - some sanitizer runtime libraries
+/// - all other MinGW libraries and Windows import libs
+///
+#[derive(Default, Clone, PartialEq, Debug)]
+pub struct LinkSelfContained {
+    /// Whether the user explicitly set `-C link-self-contained` on or off, the historical values.
+    /// Used for compatibility with the existing opt-in and target inference.
+    pub explicitly_set: Option<bool>,
+
+    /// The components that are enabled.
+    components: LinkSelfContainedComponents,
+}
+
+bitflags::bitflags! {
+    #[derive(Default)]
+    /// The `-C link-self-contained` components that can individually be enabled or disabled.
+    pub struct LinkSelfContainedComponents: u8 {
+        /// CRT objects (e.g. on `windows-gnu`, `musl`, `wasi` targets)
+        const CRT_OBJECTS = 1 << 0;
+        /// libc static library (e.g. on `musl`, `wasi` targets)
+        const LIBC        = 1 << 1;
+        /// libgcc/libunwind (e.g. on `windows-gnu`, `fuchsia`, `fortanix`, `gnullvm` targets)
+        const UNWIND      = 1 << 2;
+        /// Linker, dlltool, and their necessary libraries (e.g. on `windows-gnu` and for `rust-lld`)
+        const LINKER      = 1 << 3;
+        /// Sanitizer runtime libraries
+        const SANITIZERS  = 1 << 4;
+        /// Other MinGW libs and Windows import libs
+        const MINGW       = 1 << 5;
+    }
+}
+
+impl FromStr for LinkSelfContainedComponents {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(match s {
+            "crto" => LinkSelfContainedComponents::CRT_OBJECTS,
+            "libc" => LinkSelfContainedComponents::LIBC,
+            "unwind" => LinkSelfContainedComponents::UNWIND,
+            "linker" => LinkSelfContainedComponents::LINKER,
+            "sanitizers" => LinkSelfContainedComponents::SANITIZERS,
+            "mingw" => LinkSelfContainedComponents::MINGW,
+            _ => return Err(()),
+        })
+    }
+}
+
+impl LinkSelfContained {
+    /// Incorporates an enabled or disabled component as specified on the CLI, if possible.
+    /// For example: `+linker`, and `-crto`.
+    pub(crate) fn handle_cli_component(&mut self, component: &str) -> Result<(), ()> {
+        // Note that for example `-Cself-contained=y -Cself-contained=-linker` is not an explicit
+        // set of all values like `y` or `n` used to be. Therefore, if this flag had previously been
+        // set in bulk with its historical values, then manually setting a component clears that
+        // `explicitly_set` state.
+        if let Some(component_to_enable) = component.strip_prefix("+") {
+            self.explicitly_set = None;
+            self.components.insert(component_to_enable.parse()?);
+            Ok(())
+        } else if let Some(component_to_disable) = component.strip_prefix("-") {
+            self.explicitly_set = None;
+            self.components.remove(component_to_disable.parse()?);
+            Ok(())
+        } else {
+            Err(())
+        }
+    }
+
+    /// Turns all components on or off and records that this was done explicitly for compatibility
+    /// purposes.
+    pub(crate) fn set_all_explicitly(&mut self, enabled: bool) {
+        self.explicitly_set = Some(enabled);
+        self.components = if enabled {
+            LinkSelfContainedComponents::all()
+        } else {
+            LinkSelfContainedComponents::empty()
+        };
+    }
+
+    /// Helper creating a fully enabled `LinkSelfContained` instance. Used in tests.
+    pub fn on() -> Self {
+        let mut on = LinkSelfContained::default();
+        on.set_all_explicitly(true);
+        on
+    }
+
+    /// To help checking CLI usage while some of the values are unstable: returns whether one of the
+    /// components was set individually. This would also require the `-Zunstable-options` flag, to
+    /// be allowed.
+    fn are_unstable_variants_set(&self) -> bool {
+        let any_component_set = !self.components.is_empty();
+        self.explicitly_set.is_none() && any_component_set
+    }
+
+    /// Returns whether the self-contained linker component is enabled.
+    pub fn linker(&self) -> bool {
+        self.components.contains(LinkSelfContainedComponents::LINKER)
+    }
+}
+
 /// Used with `-Z assert-incr-state`.
 #[derive(Clone, Copy, PartialEq, Hash, Debug)]
 pub enum IncrementalStateAssertion {
@@ -212,15 +334,6 @@ pub enum IncrementalStateAssertion {
     NotLoaded,
 }
 
-impl LinkerPluginLto {
-    pub fn enabled(&self) -> bool {
-        match *self {
-            LinkerPluginLto::LinkerPlugin(_) | LinkerPluginLto::LinkerPluginAuto => true,
-            LinkerPluginLto::Disabled => false,
-        }
-    }
-}
-
 /// The different settings that can be enabled via the `-Z location-detail` flag.
 #[derive(Copy, Clone, PartialEq, Hash, Debug)]
 pub struct LocationDetail {
@@ -311,7 +424,9 @@ pub enum OutputType {
 }
 
 // Safety: Trivial C-Style enums have a stable sort order across compilation sessions.
-unsafe impl StableOrd for OutputType {}
+unsafe impl StableOrd for OutputType {
+    const CAN_USE_UNSTABLE_SORT: bool = true;
+}
 
 impl<HCX: HashStableContext> ToStableHashKey<HCX> for OutputType {
     type KeyType = Self;
@@ -333,7 +448,7 @@ impl OutputType {
         }
     }
 
-    fn shorthand(&self) -> &'static str {
+    pub fn shorthand(&self) -> &'static str {
         match *self {
             OutputType::Bitcode => "llvm-bc",
             OutputType::Assembly => "asm",
@@ -386,6 +501,18 @@ impl OutputType {
             OutputType::Exe => "",
         }
     }
+
+    pub fn is_text_output(&self) -> bool {
+        match *self {
+            OutputType::Assembly
+            | OutputType::LlvmAssembly
+            | OutputType::Mir
+            | OutputType::DepInfo => true,
+            OutputType::Bitcode | OutputType::Object | OutputType::Metadata | OutputType::Exe => {
+                false
+            }
+        }
+    }
 }
 
 /// The type of diagnostics output to generate.
@@ -438,14 +565,14 @@ pub enum ResolveDocLinks {
 /// dependency tracking for command-line arguments. Also only hash keys, since tracking
 /// should only depend on the output types, not the paths they're written to.
 #[derive(Clone, Debug, Hash, HashStable_Generic)]
-pub struct OutputTypes(BTreeMap<OutputType, Option<PathBuf>>);
+pub struct OutputTypes(BTreeMap<OutputType, Option<OutFileName>>);
 
 impl OutputTypes {
-    pub fn new(entries: &[(OutputType, Option<PathBuf>)]) -> OutputTypes {
+    pub fn new(entries: &[(OutputType, Option<OutFileName>)]) -> OutputTypes {
         OutputTypes(BTreeMap::from_iter(entries.iter().map(|&(k, ref v)| (k, v.clone()))))
     }
 
-    pub fn get(&self, key: &OutputType) -> Option<&Option<PathBuf>> {
+    pub fn get(&self, key: &OutputType) -> Option<&Option<OutFileName>> {
         self.0.get(key)
     }
 
@@ -453,11 +580,15 @@ impl OutputTypes {
         self.0.contains_key(key)
     }
 
-    pub fn keys(&self) -> BTreeMapKeysIter<'_, OutputType, Option<PathBuf>> {
+    pub fn iter(&self) -> BTreeMapIter<'_, OutputType, Option<OutFileName>> {
+        self.0.iter()
+    }
+
+    pub fn keys(&self) -> BTreeMapKeysIter<'_, OutputType, Option<OutFileName>> {
         self.0.keys()
     }
 
-    pub fn values(&self) -> BTreeMapValuesIter<'_, OutputType, Option<PathBuf>> {
+    pub fn values(&self) -> BTreeMapValuesIter<'_, OutputType, Option<OutFileName>> {
         self.0.values()
     }
 
@@ -606,10 +737,18 @@ pub enum PrintRequest {
 pub enum TraitSolver {
     /// Classic trait solver in `rustc_trait_selection::traits::select`
     Classic,
-    /// Chalk trait solver
-    Chalk,
     /// Experimental trait solver in `rustc_trait_selection::solve`
     Next,
+    /// Use the new trait solver during coherence
+    NextCoherence,
+}
+
+#[derive(Default, Debug, Copy, Clone, Hash, PartialEq, Eq)]
+pub enum DumpSolverProofTree {
+    Always,
+    OnError,
+    #[default]
+    Never,
 }
 
 pub enum Input {
@@ -658,11 +797,71 @@ impl Input {
     }
 }
 
+#[derive(Clone, Hash, Debug, HashStable_Generic, PartialEq)]
+pub enum OutFileName {
+    Real(PathBuf),
+    Stdout,
+}
+
+impl OutFileName {
+    pub fn parent(&self) -> Option<&Path> {
+        match *self {
+            OutFileName::Real(ref path) => path.parent(),
+            OutFileName::Stdout => None,
+        }
+    }
+
+    pub fn filestem(&self) -> Option<&OsStr> {
+        match *self {
+            OutFileName::Real(ref path) => path.file_stem(),
+            OutFileName::Stdout => Some(OsStr::new("stdout")),
+        }
+    }
+
+    pub fn is_stdout(&self) -> bool {
+        match *self {
+            OutFileName::Real(_) => false,
+            OutFileName::Stdout => true,
+        }
+    }
+
+    pub fn is_tty(&self) -> bool {
+        match *self {
+            OutFileName::Real(_) => false,
+            OutFileName::Stdout => atty::is(atty::Stream::Stdout),
+        }
+    }
+
+    pub fn as_path(&self) -> &Path {
+        match *self {
+            OutFileName::Real(ref path) => path.as_ref(),
+            OutFileName::Stdout => &Path::new("stdout"),
+        }
+    }
+
+    /// For a given output filename, return the actual name of the file that
+    /// can be used to write codegen data of type `flavor`. For real-path
+    /// output filenames, this would be trivial as we can just use the path.
+    /// Otherwise for stdout, return a temporary path so that the codegen data
+    /// may be later copied to stdout.
+    pub fn file_for_writing(
+        &self,
+        outputs: &OutputFilenames,
+        flavor: OutputType,
+        codegen_unit_name: Option<&str>,
+    ) -> PathBuf {
+        match *self {
+            OutFileName::Real(ref path) => path.clone(),
+            OutFileName::Stdout => outputs.temp_path(flavor, codegen_unit_name),
+        }
+    }
+}
+
 #[derive(Clone, Hash, Debug, HashStable_Generic)]
 pub struct OutputFilenames {
     pub out_directory: PathBuf,
     filestem: String,
-    pub single_output_file: Option<PathBuf>,
+    pub single_output_file: Option<OutFileName>,
     pub temps_directory: Option<PathBuf>,
     pub outputs: OutputTypes,
 }
@@ -675,7 +874,7 @@ impl OutputFilenames {
     pub fn new(
         out_directory: PathBuf,
         out_filestem: String,
-        single_output_file: Option<PathBuf>,
+        single_output_file: Option<OutFileName>,
         temps_directory: Option<PathBuf>,
         extra: String,
         outputs: OutputTypes,
@@ -689,12 +888,12 @@ impl OutputFilenames {
         }
     }
 
-    pub fn path(&self, flavor: OutputType) -> PathBuf {
+    pub fn path(&self, flavor: OutputType) -> OutFileName {
         self.outputs
             .get(&flavor)
             .and_then(|p| p.to_owned())
             .or_else(|| self.single_output_file.clone())
-            .unwrap_or_else(|| self.output_path(flavor))
+            .unwrap_or_else(|| OutFileName::Real(self.output_path(flavor)))
     }
 
     /// Gets the output path where a compilation artifact of the given type
@@ -828,6 +1027,7 @@ impl Default for Options {
             json_future_incompat: false,
             pretty: None,
             working_dir: RealFileName::LocalPath(std::env::current_dir().unwrap()),
+            color: ColorConfig::Auto,
         }
     }
 }
@@ -1308,6 +1508,7 @@ pub fn build_configuration(sess: &Session, mut user_cfg: CrateConfig) -> CrateCo
 }
 
 pub(super) fn build_target_config(
+    handler: &EarlyErrorHandler,
     opts: &Options,
     target_override: Option<Target>,
     sysroot: &Path,
@@ -1317,27 +1518,21 @@ pub(super) fn build_target_config(
         |t| Ok((t, TargetWarnings::empty())),
     );
     let (target, target_warnings) = target_result.unwrap_or_else(|e| {
-        early_error(
-            opts.error_format,
-            format!(
-                "Error loading target specification: {}. \
+        handler.early_error(format!(
+            "Error loading target specification: {}. \
                  Run `rustc --print target-list` for a list of built-in targets",
-                e
-            ),
-        )
+            e
+        ))
     });
     for warning in target_warnings.warning_messages() {
-        early_warn(opts.error_format, warning)
+        handler.early_warn(warning)
     }
 
     if !matches!(target.pointer_width, 16 | 32 | 64) {
-        early_error(
-            opts.error_format,
-            format!(
-                "target specification was invalid: unrecognized target-pointer-width {}",
-                target.pointer_width
-            ),
-        )
+        handler.early_error(format!(
+            "target specification was invalid: unrecognized target-pointer-width {}",
+            target.pointer_width
+        ))
     }
 
     target
@@ -1573,8 +1768,8 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
 }
 
 pub fn get_cmd_lint_options(
+    handler: &EarlyErrorHandler,
     matches: &getopts::Matches,
-    error_format: ErrorOutputType,
 ) -> (Vec<(String, lint::Level)>, bool, Option<lint::Level>) {
     let mut lint_opts_with_position = vec![];
     let mut describe_lints = false;
@@ -1598,14 +1793,14 @@ pub fn get_cmd_lint_options(
 
     let lint_cap = matches.opt_str("cap-lints").map(|cap| {
         lint::Level::from_str(&cap)
-            .unwrap_or_else(|| early_error(error_format, format!("unknown lint level: `{cap}`")))
+            .unwrap_or_else(|| handler.early_error(format!("unknown lint level: `{cap}`")))
     });
 
     (lint_opts, describe_lints, lint_cap)
 }
 
 /// Parses the `--color` flag.
-pub fn parse_color(matches: &getopts::Matches) -> ColorConfig {
+pub fn parse_color(handler: &EarlyErrorHandler, matches: &getopts::Matches) -> ColorConfig {
     match matches.opt_str("color").as_deref() {
         Some("auto") => ColorConfig::Auto,
         Some("always") => ColorConfig::Always,
@@ -1613,13 +1808,10 @@ pub fn parse_color(matches: &getopts::Matches) -> ColorConfig {
 
         None => ColorConfig::Auto,
 
-        Some(arg) => early_error(
-            ErrorOutputType::default(),
-            format!(
-                "argument for `--color` must be auto, \
+        Some(arg) => handler.early_error(format!(
+            "argument for `--color` must be auto, \
                  always or never (instead was `{arg}`)"
-            ),
-        ),
+        )),
     }
 }
 
@@ -1662,7 +1854,7 @@ impl JsonUnusedExterns {
 ///
 /// The first value returned is how to render JSON diagnostics, and the second
 /// is whether or not artifact notifications are enabled.
-pub fn parse_json(matches: &getopts::Matches) -> JsonConfig {
+pub fn parse_json(handler: &EarlyErrorHandler, matches: &getopts::Matches) -> JsonConfig {
     let mut json_rendered: fn(ColorConfig) -> HumanReadableErrorType =
         HumanReadableErrorType::Default;
     let mut json_color = ColorConfig::Never;
@@ -1674,10 +1866,7 @@ pub fn parse_json(matches: &getopts::Matches) -> JsonConfig {
         // won't actually be emitting any colors and anything colorized is
         // embedded in a diagnostic message anyway.
         if matches.opt_str("color").is_some() {
-            early_error(
-                ErrorOutputType::default(),
-                "cannot specify the `--color` option with `--json`",
-            );
+            handler.early_error("cannot specify the `--color` option with `--json`");
         }
 
         for sub_option in option.split(',') {
@@ -1688,10 +1877,7 @@ pub fn parse_json(matches: &getopts::Matches) -> JsonConfig {
                 "unused-externs" => json_unused_externs = JsonUnusedExterns::Loud,
                 "unused-externs-silent" => json_unused_externs = JsonUnusedExterns::Silent,
                 "future-incompat" => json_future_incompat = true,
-                s => early_error(
-                    ErrorOutputType::default(),
-                    format!("unknown `--json` option `{s}`"),
-                ),
+                s => handler.early_error(format!("unknown `--json` option `{s}`")),
             }
         }
     }
@@ -1706,6 +1892,7 @@ pub fn parse_json(matches: &getopts::Matches) -> JsonConfig {
 
 /// Parses the `--error-format` flag.
 pub fn parse_error_format(
+    handler: &mut EarlyErrorHandler,
     matches: &getopts::Matches,
     color: ColorConfig,
     json_rendered: HumanReadableErrorType,
@@ -1726,13 +1913,15 @@ pub fn parse_error_format(
             Some("pretty-json") => ErrorOutputType::Json { pretty: true, json_rendered },
             Some("short") => ErrorOutputType::HumanReadable(HumanReadableErrorType::Short(color)),
 
-            Some(arg) => early_error(
-                ErrorOutputType::HumanReadable(HumanReadableErrorType::Default(color)),
-                format!(
+            Some(arg) => {
+                handler.abort_if_error_and_set_error_format(ErrorOutputType::HumanReadable(
+                    HumanReadableErrorType::Default(color),
+                ));
+                handler.early_error(format!(
                     "argument for `--error-format` must be `human`, `json` or \
                      `short` (instead was `{arg}`)"
-                ),
-            ),
+                ))
+            }
         }
     } else {
         ErrorOutputType::HumanReadable(HumanReadableErrorType::Default(color))
@@ -1745,10 +1934,7 @@ pub fn parse_error_format(
         // `--error-format=json`. This means that `--json` is specified we
         // should actually be emitting JSON blobs.
         _ if !matches.opt_strs("json").is_empty() => {
-            early_error(
-                ErrorOutputType::default(),
-                "using `--json` requires also using `--error-format=json`",
-            );
+            handler.early_error("using `--json` requires also using `--error-format=json`");
         }
 
         _ => {}
@@ -1757,16 +1943,13 @@ pub fn parse_error_format(
     error_format
 }
 
-pub fn parse_crate_edition(matches: &getopts::Matches) -> Edition {
+pub fn parse_crate_edition(handler: &EarlyErrorHandler, matches: &getopts::Matches) -> Edition {
     let edition = match matches.opt_str("edition") {
         Some(arg) => Edition::from_str(&arg).unwrap_or_else(|_| {
-            early_error(
-                ErrorOutputType::default(),
-                format!(
-                    "argument for `--edition` must be one of: \
+            handler.early_error(format!(
+                "argument for `--edition` must be one of: \
                      {EDITION_NAME_LIST}. (instead was `{arg}`)"
-                ),
-            )
+            ))
         }),
         None => DEFAULT_EDITION,
     };
@@ -1781,39 +1964,42 @@ pub fn parse_crate_edition(matches: &getopts::Matches) -> Edition {
         } else {
             format!("edition {edition} is unstable and only available with -Z unstable-options")
         };
-        early_error(ErrorOutputType::default(), msg)
+        handler.early_error(msg)
     }
 
     edition
 }
 
 fn check_error_format_stability(
+    handler: &mut EarlyErrorHandler,
     unstable_opts: &UnstableOptions,
     error_format: ErrorOutputType,
     json_rendered: HumanReadableErrorType,
 ) {
     if !unstable_opts.unstable_options {
         if let ErrorOutputType::Json { pretty: true, json_rendered } = error_format {
-            early_error(
-                ErrorOutputType::Json { pretty: false, json_rendered },
-                "`--error-format=pretty-json` is unstable",
-            );
+            handler.abort_if_error_and_set_error_format(ErrorOutputType::Json {
+                pretty: false,
+                json_rendered,
+            });
+            handler.early_error("`--error-format=pretty-json` is unstable");
         }
         if let ErrorOutputType::HumanReadable(HumanReadableErrorType::AnnotateSnippet(_)) =
             error_format
         {
-            early_error(
-                ErrorOutputType::Json { pretty: false, json_rendered },
-                "`--error-format=human-annotate-rs` is unstable",
-            );
+            handler.abort_if_error_and_set_error_format(ErrorOutputType::Json {
+                pretty: false,
+                json_rendered,
+            });
+            handler.early_error("`--error-format=human-annotate-rs` is unstable");
         }
     }
 }
 
 fn parse_output_types(
+    handler: &EarlyErrorHandler,
     unstable_opts: &UnstableOptions,
     matches: &getopts::Matches,
-    error_format: ErrorOutputType,
 ) -> OutputTypes {
     let mut output_types = BTreeMap::new();
     if !unstable_opts.parse_only {
@@ -1821,16 +2007,16 @@ fn parse_output_types(
             for output_type in list.split(',') {
                 let (shorthand, path) = match output_type.split_once('=') {
                     None => (output_type, None),
-                    Some((shorthand, path)) => (shorthand, Some(PathBuf::from(path))),
+                    Some((shorthand, "-")) => (shorthand, Some(OutFileName::Stdout)),
+                    Some((shorthand, path)) => {
+                        (shorthand, Some(OutFileName::Real(PathBuf::from(path))))
+                    }
                 };
                 let output_type = OutputType::from_shorthand(shorthand).unwrap_or_else(|| {
-                    early_error(
-                        error_format,
-                        format!(
-                            "unknown emission type: `{shorthand}` - expected one of: {display}",
-                            display = OutputType::shorthands_display(),
-                        ),
-                    )
+                    handler.early_error(format!(
+                        "unknown emission type: `{shorthand}` - expected one of: {display}",
+                        display = OutputType::shorthands_display(),
+                    ))
                 });
                 output_types.insert(output_type, path);
             }
@@ -1843,9 +2029,9 @@ fn parse_output_types(
 }
 
 fn should_override_cgus_and_disable_thinlto(
+    handler: &EarlyErrorHandler,
     output_types: &OutputTypes,
     matches: &getopts::Matches,
-    error_format: ErrorOutputType,
     mut codegen_units: Option<usize>,
 ) -> (bool, Option<usize>) {
     let mut disable_local_thinlto = false;
@@ -1863,15 +2049,12 @@ fn should_override_cgus_and_disable_thinlto(
             Some(n) if n > 1 => {
                 if matches.opt_present("o") {
                     for ot in &incompatible {
-                        early_warn(
-                            error_format,
-                            format!(
-                                "`--emit={ot}` with `-o` incompatible with \
+                        handler.early_warn(format!(
+                            "`--emit={ot}` with `-o` incompatible with \
                                  `-C codegen-units=N` for N > 1",
-                            ),
-                        );
+                        ));
                     }
-                    early_warn(error_format, "resetting to default -C codegen-units=1");
+                    handler.early_warn("resetting to default -C codegen-units=1");
                     codegen_units = Some(1);
                     disable_local_thinlto = true;
                 }
@@ -1884,27 +2067,27 @@ fn should_override_cgus_and_disable_thinlto(
     }
 
     if codegen_units == Some(0) {
-        early_error(error_format, "value for codegen units must be a positive non-zero integer");
+        handler.early_error("value for codegen units must be a positive non-zero integer");
     }
 
     (disable_local_thinlto, codegen_units)
 }
 
-fn check_thread_count(unstable_opts: &UnstableOptions, error_format: ErrorOutputType) {
+fn check_thread_count(handler: &EarlyErrorHandler, unstable_opts: &UnstableOptions) {
     if unstable_opts.threads == 0 {
-        early_error(error_format, "value for threads must be a positive non-zero integer");
+        handler.early_error("value for threads must be a positive non-zero integer");
     }
 
     if unstable_opts.threads > 1 && unstable_opts.fuel.is_some() {
-        early_error(error_format, "optimization fuel is incompatible with multiple threads");
+        handler.early_error("optimization fuel is incompatible with multiple threads");
     }
 }
 
 fn collect_print_requests(
+    handler: &EarlyErrorHandler,
     cg: &mut CodegenOptions,
     unstable_opts: &mut UnstableOptions,
     matches: &getopts::Matches,
-    error_format: ErrorOutputType,
 ) -> Vec<PrintRequest> {
     let mut prints = Vec::<PrintRequest>::new();
     if cg.target_cpu.as_ref().is_some_and(|s| s == "help") {
@@ -1944,8 +2127,7 @@ fn collect_print_requests(
                 if unstable_opts.unstable_options {
                     PrintRequest::TargetSpec
                 } else {
-                    early_error(
-                        error_format,
+                    handler.early_error(
                         "the `-Z unstable-options` flag must also be passed to \
                          enable the target-spec-json print option",
                     );
@@ -1955,8 +2137,7 @@ fn collect_print_requests(
                 if unstable_opts.unstable_options {
                     PrintRequest::AllTargetSpecs
                 } else {
-                    early_error(
-                        error_format,
+                    handler.early_error(
                         "the `-Z unstable-options` flag must also be passed to \
                          enable the all-target-specs-json print option",
                     );
@@ -1967,10 +2148,9 @@ fn collect_print_requests(
                 let prints =
                     PRINT_REQUESTS.iter().map(|(name, _)| format!("`{name}`")).collect::<Vec<_>>();
                 let prints = prints.join(", ");
-                early_error(
-                    error_format,
-                    format!("unknown print request `{req}`. Valid print requests are: {prints}"),
-                );
+                handler.early_error(format!(
+                    "unknown print request `{req}`. Valid print requests are: {prints}"
+                ));
             }
         }
     }));
@@ -1979,14 +2159,14 @@ fn collect_print_requests(
 }
 
 pub fn parse_target_triple(
+    handler: &EarlyErrorHandler,
     matches: &getopts::Matches,
-    error_format: ErrorOutputType,
 ) -> TargetTriple {
     match matches.opt_str("target") {
         Some(target) if target.ends_with(".json") => {
             let path = Path::new(&target);
             TargetTriple::from_path(path).unwrap_or_else(|_| {
-                early_error(error_format, format!("target file {path:?} does not exist"))
+                handler.early_error(format!("target file {path:?} does not exist"))
             })
         }
         Some(target) => TargetTriple::TargetTriple(target),
@@ -1995,9 +2175,9 @@ pub fn parse_target_triple(
 }
 
 fn parse_opt_level(
+    handler: &EarlyErrorHandler,
     matches: &getopts::Matches,
     cg: &CodegenOptions,
-    error_format: ErrorOutputType,
 ) -> OptLevel {
     // The `-O` and `-C opt-level` flags specify the same setting, so we want to be able
     // to use them interchangeably. However, because they're technically different flags,
@@ -2025,13 +2205,10 @@ fn parse_opt_level(
             "s" => OptLevel::Size,
             "z" => OptLevel::SizeMin,
             arg => {
-                early_error(
-                    error_format,
-                    format!(
-                        "optimization level needs to be \
+                handler.early_error(format!(
+                    "optimization level needs to be \
                             between 0-3, s or z (instead was `{arg}`)"
-                    ),
-                );
+                ));
             }
         }
     }
@@ -2051,23 +2228,23 @@ fn select_debuginfo(matches: &getopts::Matches, cg: &CodegenOptions) -> DebugInf
 }
 
 pub(crate) fn parse_assert_incr_state(
+    handler: &EarlyErrorHandler,
     opt_assertion: &Option<String>,
-    error_format: ErrorOutputType,
 ) -> Option<IncrementalStateAssertion> {
     match opt_assertion {
         Some(s) if s.as_str() == "loaded" => Some(IncrementalStateAssertion::Loaded),
         Some(s) if s.as_str() == "not-loaded" => Some(IncrementalStateAssertion::NotLoaded),
         Some(s) => {
-            early_error(error_format, format!("unexpected incremental state assertion value: {s}"))
+            handler.early_error(format!("unexpected incremental state assertion value: {s}"))
         }
         None => None,
     }
 }
 
 fn parse_native_lib_kind(
+    handler: &EarlyErrorHandler,
     matches: &getopts::Matches,
     kind: &str,
-    error_format: ErrorOutputType,
 ) -> (NativeLibKind, Option<bool>) {
     let (kind, modifiers) = match kind.split_once(':') {
         None => (kind, None),
@@ -2085,35 +2262,31 @@ fn parse_native_lib_kind(
                 } else {
                     ", the `-Z unstable-options` flag must also be passed to use it"
                 };
-                early_error(error_format, format!("library kind `link-arg` is unstable{why}"))
+                handler.early_error(format!("library kind `link-arg` is unstable{why}"))
             }
             NativeLibKind::LinkArg
         }
-        _ => early_error(
-            error_format,
-            format!(
-                "unknown library kind `{kind}`, expected one of: static, dylib, framework, link-arg"
-            ),
-        ),
+        _ => handler.early_error(format!(
+            "unknown library kind `{kind}`, expected one of: static, dylib, framework, link-arg"
+        )),
     };
     match modifiers {
         None => (kind, None),
-        Some(modifiers) => parse_native_lib_modifiers(kind, modifiers, error_format, matches),
+        Some(modifiers) => parse_native_lib_modifiers(handler, kind, modifiers, matches),
     }
 }
 
 fn parse_native_lib_modifiers(
+    handler: &EarlyErrorHandler,
     mut kind: NativeLibKind,
     modifiers: &str,
-    error_format: ErrorOutputType,
     matches: &getopts::Matches,
 ) -> (NativeLibKind, Option<bool>) {
     let mut verbatim = None;
     for modifier in modifiers.split(',') {
         let (modifier, value) = match modifier.strip_prefix(['+', '-']) {
             Some(m) => (m, modifier.starts_with('+')),
-            None => early_error(
-                error_format,
+            None => handler.early_error(
                 "invalid linking modifier syntax, expected '+' or '-' prefix \
                  before one of: bundle, verbatim, whole-archive, as-needed",
             ),
@@ -2126,21 +2299,20 @@ fn parse_native_lib_modifiers(
                 } else {
                     ", the `-Z unstable-options` flag must also be passed to use it"
                 };
-                early_error(error_format, format!("linking modifier `{modifier}` is unstable{why}"))
+                handler.early_error(format!("linking modifier `{modifier}` is unstable{why}"))
             }
         };
         let assign_modifier = |dst: &mut Option<bool>| {
             if dst.is_some() {
                 let msg = format!("multiple `{modifier}` modifiers in a single `-l` option");
-                early_error(error_format, msg)
+                handler.early_error(msg)
             } else {
                 *dst = Some(value);
             }
         };
         match (modifier, &mut kind) {
             ("bundle", NativeLibKind::Static { bundle, .. }) => assign_modifier(bundle),
-            ("bundle", _) => early_error(
-                error_format,
+            ("bundle", _) => handler.early_error(
                 "linking modifier `bundle` is only compatible with `static` linking kind",
             ),
 
@@ -2149,8 +2321,7 @@ fn parse_native_lib_modifiers(
             ("whole-archive", NativeLibKind::Static { whole_archive, .. }) => {
                 assign_modifier(whole_archive)
             }
-            ("whole-archive", _) => early_error(
-                error_format,
+            ("whole-archive", _) => handler.early_error(
                 "linking modifier `whole-archive` is only compatible with `static` linking kind",
             ),
 
@@ -2159,28 +2330,24 @@ fn parse_native_lib_modifiers(
                 report_unstable_modifier();
                 assign_modifier(as_needed)
             }
-            ("as-needed", _) => early_error(
-                error_format,
+            ("as-needed", _) => handler.early_error(
                 "linking modifier `as-needed` is only compatible with \
                  `dylib` and `framework` linking kinds",
             ),
 
             // Note: this error also excludes the case with empty modifier
             // string, like `modifiers = ""`.
-            _ => early_error(
-                error_format,
-                format!(
-                    "unknown linking modifier `{modifier}`, expected one \
+            _ => handler.early_error(format!(
+                "unknown linking modifier `{modifier}`, expected one \
                      of: bundle, verbatim, whole-archive, as-needed"
-                ),
-            ),
+            )),
         }
     }
 
     (kind, verbatim)
 }
 
-fn parse_libs(matches: &getopts::Matches, error_format: ErrorOutputType) -> Vec<NativeLib> {
+fn parse_libs(handler: &EarlyErrorHandler, matches: &getopts::Matches) -> Vec<NativeLib> {
     matches
         .opt_strs("l")
         .into_iter()
@@ -2194,7 +2361,7 @@ fn parse_libs(matches: &getopts::Matches, error_format: ErrorOutputType) -> Vec<
             let (name, kind, verbatim) = match s.split_once('=') {
                 None => (s, NativeLibKind::Unspecified, None),
                 Some((kind, name)) => {
-                    let (kind, verbatim) = parse_native_lib_kind(matches, kind, error_format);
+                    let (kind, verbatim) = parse_native_lib_kind(handler, matches, kind);
                     (name.to_string(), kind, verbatim)
                 }
             };
@@ -2204,7 +2371,7 @@ fn parse_libs(matches: &getopts::Matches, error_format: ErrorOutputType) -> Vec<
                 Some((name, new_name)) => (name.to_string(), Some(new_name.to_owned())),
             };
             if name.is_empty() {
-                early_error(error_format, "library name must not be empty");
+                handler.early_error("library name must not be empty");
             }
             NativeLib { name, new_name, kind, verbatim }
         })
@@ -2212,9 +2379,9 @@ fn parse_libs(matches: &getopts::Matches, error_format: ErrorOutputType) -> Vec<
 }
 
 pub fn parse_externs(
+    handler: &EarlyErrorHandler,
     matches: &getopts::Matches,
     unstable_opts: &UnstableOptions,
-    error_format: ErrorOutputType,
 ) -> Externs {
     let is_unstable_enabled = unstable_opts.unstable_options;
     let mut externs: BTreeMap<String, ExternEntry> = BTreeMap::new();
@@ -2278,8 +2445,7 @@ pub fn parse_externs(
         let mut force = false;
         if let Some(opts) = options {
             if !is_unstable_enabled {
-                early_error(
-                    error_format,
+                handler.early_error(
                     "the `-Z unstable-options` flag must also be passed to \
                      enable `--extern` options",
                 );
@@ -2291,15 +2457,14 @@ pub fn parse_externs(
                         if let ExternLocation::ExactPaths(_) = &entry.location {
                             add_prelude = false;
                         } else {
-                            early_error(
-                                error_format,
+                            handler.early_error(
                                 "the `noprelude` --extern option requires a file path",
                             );
                         }
                     }
                     "nounused" => nounused_dep = true,
                     "force" => force = true,
-                    _ => early_error(error_format, format!("unknown --extern option `{opt}`")),
+                    _ => handler.early_error(format!("unknown --extern option `{opt}`")),
                 }
             }
         }
@@ -2318,18 +2483,15 @@ pub fn parse_externs(
 }
 
 fn parse_remap_path_prefix(
+    handler: &EarlyErrorHandler,
     matches: &getopts::Matches,
     unstable_opts: &UnstableOptions,
-    error_format: ErrorOutputType,
 ) -> Vec<(PathBuf, PathBuf)> {
     let mut mapping: Vec<(PathBuf, PathBuf)> = matches
         .opt_strs("remap-path-prefix")
         .into_iter()
         .map(|remap| match remap.rsplit_once('=') {
-            None => early_error(
-                error_format,
-                "--remap-path-prefix must contain '=' between FROM and TO",
-            ),
+            None => handler.early_error("--remap-path-prefix must contain '=' between FROM and TO"),
             Some((from, to)) => (PathBuf::from(from), PathBuf::from(to)),
         })
         .collect();
@@ -2345,86 +2507,75 @@ fn parse_remap_path_prefix(
 
 // JUSTIFICATION: before wrapper fn is available
 #[allow(rustc::bad_opt_access)]
-pub fn build_session_options(matches: &getopts::Matches) -> Options {
-    let color = parse_color(matches);
+pub fn build_session_options(
+    handler: &mut EarlyErrorHandler,
+    matches: &getopts::Matches,
+) -> Options {
+    let color = parse_color(handler, matches);
 
-    let edition = parse_crate_edition(matches);
+    let edition = parse_crate_edition(handler, matches);
 
     let JsonConfig {
         json_rendered,
         json_artifact_notifications,
         json_unused_externs,
         json_future_incompat,
-    } = parse_json(matches);
+    } = parse_json(handler, matches);
 
-    let error_format = parse_error_format(matches, color, json_rendered);
+    let error_format = parse_error_format(handler, matches, color, json_rendered);
 
     let diagnostic_width = matches.opt_get("diagnostic-width").unwrap_or_else(|_| {
-        early_error(error_format, "`--diagnostic-width` must be an positive integer");
+        handler.early_error("`--diagnostic-width` must be an positive integer");
     });
 
     let unparsed_crate_types = matches.opt_strs("crate-type");
     let crate_types = parse_crate_types_from_list(unparsed_crate_types)
-        .unwrap_or_else(|e| early_error(error_format, e));
+        .unwrap_or_else(|e| handler.early_error(e));
 
-    let mut unstable_opts = UnstableOptions::build(matches, error_format);
-    let (lint_opts, describe_lints, lint_cap) = get_cmd_lint_options(matches, error_format);
+    let mut unstable_opts = UnstableOptions::build(handler, matches);
+    let (lint_opts, describe_lints, lint_cap) = get_cmd_lint_options(handler, matches);
 
-    check_error_format_stability(&unstable_opts, error_format, json_rendered);
+    check_error_format_stability(handler, &unstable_opts, error_format, json_rendered);
 
     if !unstable_opts.unstable_options && json_unused_externs.is_enabled() {
-        early_error(
-            error_format,
+        handler.early_error(
             "the `-Z unstable-options` flag must also be passed to enable \
             the flag `--json=unused-externs`",
         );
     }
 
-    let output_types = parse_output_types(&unstable_opts, matches, error_format);
+    let output_types = parse_output_types(handler, &unstable_opts, matches);
 
-    let mut cg = CodegenOptions::build(matches, error_format);
-    let (disable_local_thinlto, mut codegen_units) = should_override_cgus_and_disable_thinlto(
-        &output_types,
-        matches,
-        error_format,
-        cg.codegen_units,
-    );
+    let mut cg = CodegenOptions::build(handler, matches);
+    let (disable_local_thinlto, mut codegen_units) =
+        should_override_cgus_and_disable_thinlto(handler, &output_types, matches, cg.codegen_units);
 
-    check_thread_count(&unstable_opts, error_format);
+    check_thread_count(handler, &unstable_opts);
 
     let incremental = cg.incremental.as_ref().map(PathBuf::from);
 
-    let assert_incr_state = parse_assert_incr_state(&unstable_opts.assert_incr_state, error_format);
+    let assert_incr_state = parse_assert_incr_state(handler, &unstable_opts.assert_incr_state);
 
     if unstable_opts.profile && incremental.is_some() {
-        early_error(
-            error_format,
-            "can't instrument with gcov profiling when compiling incrementally",
-        );
+        handler.early_error("can't instrument with gcov profiling when compiling incrementally");
     }
     if unstable_opts.profile {
         match codegen_units {
             Some(1) => {}
             None => codegen_units = Some(1),
-            Some(_) => early_error(
-                error_format,
-                "can't instrument with gcov profiling with multiple codegen units",
-            ),
+            Some(_) => handler
+                .early_error("can't instrument with gcov profiling with multiple codegen units"),
         }
     }
 
     if cg.profile_generate.enabled() && cg.profile_use.is_some() {
-        early_error(
-            error_format,
-            "options `-C profile-generate` and `-C profile-use` are exclusive",
-        );
+        handler.early_error("options `-C profile-generate` and `-C profile-use` are exclusive");
     }
 
     if unstable_opts.profile_sample_use.is_some()
         && (cg.profile_generate.enabled() || cg.profile_use.is_some())
     {
-        early_error(
-            error_format,
+        handler.early_error(
             "option `-Z profile-sample-use` cannot be used with `-C profile-generate` or `-C profile-use`",
         );
     }
@@ -2433,23 +2584,19 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     // precedence.
     match (cg.symbol_mangling_version, unstable_opts.symbol_mangling_version) {
         (Some(smv_c), Some(smv_z)) if smv_c != smv_z => {
-            early_error(
-                error_format,
+            handler.early_error(
                 "incompatible values passed for `-C symbol-mangling-version` \
                 and `-Z symbol-mangling-version`",
             );
         }
         (Some(SymbolManglingVersion::V0), _) => {}
         (Some(_), _) if !unstable_opts.unstable_options => {
-            early_error(
-                error_format,
-                "`-C symbol-mangling-version=legacy` requires `-Z unstable-options`",
-            );
+            handler
+                .early_error("`-C symbol-mangling-version=legacy` requires `-Z unstable-options`");
         }
         (None, None) => {}
         (None, smv) => {
-            early_warn(
-                error_format,
+            handler.early_warn(
                 "`-Z symbol-mangling-version` is deprecated; use `-C symbol-mangling-version`",
             );
             cg.symbol_mangling_version = smv;
@@ -2461,25 +2608,19 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     // precedence.
     match (cg.instrument_coverage, unstable_opts.instrument_coverage) {
         (Some(ic_c), Some(ic_z)) if ic_c != ic_z => {
-            early_error(
-                error_format,
+            handler.early_error(
                 "incompatible values passed for `-C instrument-coverage` \
                 and `-Z instrument-coverage`",
             );
         }
         (Some(InstrumentCoverage::Off | InstrumentCoverage::All), _) => {}
         (Some(_), _) if !unstable_opts.unstable_options => {
-            early_error(
-                error_format,
-                "`-C instrument-coverage=except-*` requires `-Z unstable-options`",
-            );
+            handler.early_error("`-C instrument-coverage=except-*` requires `-Z unstable-options`");
         }
         (None, None) => {}
         (None, ic) => {
-            early_warn(
-                error_format,
-                "`-Z instrument-coverage` is deprecated; use `-C instrument-coverage`",
-            );
+            handler
+                .early_warn("`-Z instrument-coverage` is deprecated; use `-C instrument-coverage`");
             cg.instrument_coverage = ic;
         }
         _ => {}
@@ -2487,8 +2628,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 
     if cg.instrument_coverage.is_some() && cg.instrument_coverage != Some(InstrumentCoverage::Off) {
         if cg.profile_generate.enabled() || cg.profile_use.is_some() {
-            early_error(
-                error_format,
+            handler.early_error(
                 "option `-C instrument-coverage` is not compatible with either `-C profile-use` \
                 or `-C profile-generate`",
             );
@@ -2501,8 +2641,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         match cg.symbol_mangling_version {
             None => cg.symbol_mangling_version = Some(SymbolManglingVersion::V0),
             Some(SymbolManglingVersion::Legacy) => {
-                early_warn(
-                    error_format,
+                handler.early_warn(
                     "-C instrument-coverage requires symbol mangling version `v0`, \
                     but `-C symbol-mangling-version=legacy` was specified",
                 );
@@ -2518,20 +2657,44 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     if !cg.embed_bitcode {
         match cg.lto {
             LtoCli::No | LtoCli::Unspecified => {}
-            LtoCli::Yes | LtoCli::NoParam | LtoCli::Thin | LtoCli::Fat => early_error(
-                error_format,
-                "options `-C embed-bitcode=no` and `-C lto` are incompatible",
-            ),
+            LtoCli::Yes | LtoCli::NoParam | LtoCli::Thin | LtoCli::Fat => {
+                handler.early_error("options `-C embed-bitcode=no` and `-C lto` are incompatible")
+            }
+        }
+    }
+
+    // For testing purposes, until we have more feedback about these options: ensure `-Z
+    // unstable-options` is required when using the unstable `-C link-self-contained` options, like
+    // `-C link-self-contained=+linker`, and when using the unstable `-C linker-flavor` options, like
+    // `-C linker-flavor=gnu-lld-cc`.
+    if !nightly_options::is_unstable_enabled(matches) {
+        let uses_unstable_self_contained_option =
+            cg.link_self_contained.are_unstable_variants_set();
+        if uses_unstable_self_contained_option {
+            handler.early_error(
+                "only `-C link-self-contained` values `y`/`yes`/`on`/`n`/`no`/`off` are stable, \
+                the `-Z unstable-options` flag must also be passed to use the unstable values",
+            );
+        }
+
+        if let Some(flavor) = cg.linker_flavor {
+            if flavor.is_unstable() {
+                handler.early_error(format!(
+                    "the linker flavor `{}` is unstable, the `-Z unstable-options` \
+                        flag must also be passed to use the unstable values",
+                    flavor.desc()
+                ));
+            }
         }
     }
 
-    let prints = collect_print_requests(&mut cg, &mut unstable_opts, matches, error_format);
+    let prints = collect_print_requests(handler, &mut cg, &mut unstable_opts, matches);
 
     let cg = cg;
 
     let sysroot_opt = matches.opt_str("sysroot").map(|m| PathBuf::from(&m));
-    let target_triple = parse_target_triple(matches, error_format);
-    let opt_level = parse_opt_level(matches, &cg, error_format);
+    let target_triple = parse_target_triple(handler, matches);
+    let opt_level = parse_opt_level(handler, matches, &cg);
     // The `-g` and `-C debuginfo` flags specify the same setting, so we want to be able
     // to use them interchangeably. See the note above (regarding `-O` and `-C opt-level`)
     // for more details.
@@ -2540,28 +2703,32 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 
     let mut search_paths = vec![];
     for s in &matches.opt_strs("L") {
-        search_paths.push(SearchPath::from_cli_opt(s, error_format));
+        search_paths.push(SearchPath::from_cli_opt(handler, s));
     }
 
-    let libs = parse_libs(matches, error_format);
+    let libs = parse_libs(handler, matches);
 
     let test = matches.opt_present("test");
 
     if !cg.remark.is_empty() && debuginfo == DebugInfo::None {
-        early_warn(error_format, "-C remark requires \"-C debuginfo=n\" to show source locations");
+        handler.early_warn("-C remark requires \"-C debuginfo=n\" to show source locations");
     }
 
-    let externs = parse_externs(matches, &unstable_opts, error_format);
+    if cg.remark.is_empty() && unstable_opts.remark_dir.is_some() {
+        handler.early_warn("using -Z remark-dir without enabling remarks using e.g. -C remark=all");
+    }
+
+    let externs = parse_externs(handler, matches, &unstable_opts);
 
     let crate_name = matches.opt_str("crate-name");
 
-    let remap_path_prefix = parse_remap_path_prefix(matches, &unstable_opts, error_format);
+    let remap_path_prefix = parse_remap_path_prefix(handler, matches, &unstable_opts);
 
-    let pretty = parse_pretty(&unstable_opts, error_format);
+    let pretty = parse_pretty(handler, &unstable_opts);
 
     // query-dep-graph is required if dump-dep-graph is given #106736
     if unstable_opts.dump_dep_graph && !unstable_opts.query_dep_graph {
-        early_error(error_format, "can't dump dependency graph without `-Z query-dep-graph`");
+        handler.early_error("can't dump dependency graph without `-Z query-dep-graph`");
     }
 
     // Try to find a directory containing the Rust `src`, for more details see
@@ -2593,7 +2760,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     };
 
     let working_dir = std::env::current_dir().unwrap_or_else(|e| {
-        early_error(error_format, format!("Current directory is invalid: {e}"));
+        handler.early_error(format!("Current directory is invalid: {e}"));
     });
 
     let remap = FilePathMapping::new(remap_path_prefix.clone());
@@ -2641,10 +2808,11 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         json_future_incompat,
         pretty,
         working_dir,
+        color,
     }
 }
 
-fn parse_pretty(unstable_opts: &UnstableOptions, efmt: ErrorOutputType) -> Option<PpMode> {
+fn parse_pretty(handler: &EarlyErrorHandler, unstable_opts: &UnstableOptions) -> Option<PpMode> {
     use PpMode::*;
 
     let first = match unstable_opts.unpretty.as_deref()? {
@@ -2663,16 +2831,13 @@ fn parse_pretty(unstable_opts: &UnstableOptions, efmt: ErrorOutputType) -> Optio
         "thir-flat" => ThirFlat,
         "mir" => Mir,
         "mir-cfg" => MirCFG,
-        name => early_error(
-            efmt,
-            format!(
-                "argument to `unpretty` must be one of `normal`, `identified`, \
+        name => handler.early_error(format!(
+            "argument to `unpretty` must be one of `normal`, `identified`, \
                             `expanded`, `expanded,identified`, `expanded,hygiene`, \
                             `ast-tree`, `ast-tree,expanded`, `hir`, `hir,identified`, \
                             `hir,typed`, `hir-tree`, `thir-tree`, `thir-flat`, `mir` or \
                             `mir-cfg`; got {name}"
-            ),
-        ),
+        )),
     };
     debug!("got unpretty option: {first:?}");
     Some(first)
@@ -2712,8 +2877,8 @@ pub fn parse_crate_types_from_list(list_list: Vec<String>) -> Result<Vec<CrateTy
 }
 
 pub mod nightly_options {
-    use super::{ErrorOutputType, OptionStability, RustcOptGroup};
-    use crate::early_error;
+    use super::{OptionStability, RustcOptGroup};
+    use crate::EarlyErrorHandler;
     use rustc_feature::UnstableFeatures;
 
     pub fn is_unstable_enabled(matches: &getopts::Matches) -> bool {
@@ -2729,7 +2894,11 @@ pub mod nightly_options {
         UnstableFeatures::from_environment(krate).is_nightly_build()
     }
 
-    pub fn check_nightly_options(matches: &getopts::Matches, flags: &[RustcOptGroup]) {
+    pub fn check_nightly_options(
+        handler: &EarlyErrorHandler,
+        matches: &getopts::Matches,
+        flags: &[RustcOptGroup],
+    ) {
         let has_z_unstable_option = matches.opt_strs("Z").iter().any(|x| *x == "unstable-options");
         let really_allows_unstable_options = match_is_nightly_build(matches);
 
@@ -2741,14 +2910,11 @@ pub mod nightly_options {
                 continue;
             }
             if opt.name != "Z" && !has_z_unstable_option {
-                early_error(
-                    ErrorOutputType::default(),
-                    format!(
-                        "the `-Z unstable-options` flag must also be passed to enable \
+                handler.early_error(format!(
+                    "the `-Z unstable-options` flag must also be passed to enable \
                          the flag `{}`",
-                        opt.name
-                    ),
-                );
+                    opt.name
+                ));
             }
             if really_allows_unstable_options {
                 continue;
@@ -2759,7 +2925,12 @@ pub mod nightly_options {
                         "the option `{}` is only accepted on the nightly compiler",
                         opt.name
                     );
-                    early_error(ErrorOutputType::default(), msg);
+                    let _ = handler.early_error_no_abort(msg);
+                    handler.early_note("selecting a toolchain with `+toolchain` arguments require a rustup proxy; see <https://rust-lang.github.io/rustup/concepts/index.html>");
+                    handler.early_help(
+                        "consider switching to a nightly toolchain: `rustup default nightly`",
+                    );
+                    handler.early_note("for more information about Rust's stability policy, see <https://doc.rust-lang.org/book/appendix-07-nightly-rust.html#unstable-features>");
                 }
                 OptionStability::Stable => {}
             }
@@ -2892,7 +3063,7 @@ pub(crate) mod dep_tracking {
     use super::{
         BranchProtection, CFGuard, CFProtection, CrateType, DebugInfo, ErrorOutputType,
         InstrumentCoverage, InstrumentXRay, LdImpl, LinkerPluginLto, LocationDetail, LtoCli,
-        OomStrategy, OptLevel, OutputType, OutputTypes, Passes, ResolveDocLinks,
+        OomStrategy, OptLevel, OutFileName, OutputType, OutputTypes, Passes, ResolveDocLinks,
         SourceFileHashAlgorithm, SplitDwarfKind, SwitchWithOptPath, SymbolManglingVersion,
         TraitSolver, TrimmedDefPaths,
     };
@@ -2990,6 +3161,7 @@ pub(crate) mod dep_tracking {
         SourceFileHashAlgorithm,
         TrimmedDefPaths,
         Option<LdImpl>,
+        OutFileName,
         OutputType,
         RealFileName,
         LocationDetail,
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index 546c0fa8e..4a3e668da 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -422,3 +422,11 @@ pub fn report_lit_error(sess: &ParseSess, err: LitError, lit: token::Lit, span:
 pub struct OptimisationFuelExhausted {
     pub msg: String,
 }
+
+#[derive(Diagnostic)]
+#[diag(session_incompatible_linker_flavor)]
+#[note]
+pub struct IncompatibleLinkerFlavor {
+    pub flavor: &'static str,
+    pub compatible_list: String,
+}
diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index 590a68c66..d57aa820f 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -27,7 +27,7 @@ pub use lint::{declare_lint, declare_lint_pass, declare_tool_lint, impl_lint_pas
 pub use rustc_lint_defs as lint;
 pub mod parse;
 
-mod code_stats;
+pub mod code_stats;
 #[macro_use]
 pub mod config;
 pub mod cstore;
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 2c4c4a7a6..7840a0ecf 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -1,10 +1,10 @@
 use crate::config::*;
 
-use crate::early_error;
-use crate::lint;
 use crate::search_paths::SearchPath;
 use crate::utils::NativeLib;
+use crate::{lint, EarlyErrorHandler};
 use rustc_data_structures::profiling::TimePassesFormat;
+use rustc_errors::ColorConfig;
 use rustc_errors::{LanguageIdentifier, TerminalUrl};
 use rustc_target::spec::{CodeModel, LinkerFlavorCli, MergeFunctions, PanicStrategy, SanitizerSet};
 use rustc_target::spec::{
@@ -213,6 +213,7 @@ top_level_options!(
 
         /// The (potentially remapped) working directory
         working_dir: RealFileName [TRACKED],
+        color: ColorConfig [UNTRACKED],
     }
 );
 
@@ -245,10 +246,10 @@ macro_rules! options {
 
     impl $struct_name {
         pub fn build(
+            handler: &EarlyErrorHandler,
             matches: &getopts::Matches,
-            error_format: ErrorOutputType,
         ) -> $struct_name {
-            build_options(matches, $stat, $prefix, $outputname, error_format)
+            build_options(handler, matches, $stat, $prefix, $outputname)
         }
 
         fn dep_tracking_hash(&self, for_crate_hash: bool, error_format: ErrorOutputType) -> u64 {
@@ -309,11 +310,11 @@ type OptionSetter<O> = fn(&mut O, v: Option<&str>) -> bool;
 type OptionDescrs<O> = &'static [(&'static str, OptionSetter<O>, &'static str, &'static str)];
 
 fn build_options<O: Default>(
+    handler: &EarlyErrorHandler,
     matches: &getopts::Matches,
     descrs: OptionDescrs<O>,
     prefix: &str,
     outputname: &str,
-    error_format: ErrorOutputType,
 ) -> O {
     let mut op = O::default();
     for option in matches.opt_strs(prefix) {
@@ -327,15 +328,13 @@ fn build_options<O: Default>(
             Some((_, setter, type_desc, _)) => {
                 if !setter(&mut op, value) {
                     match value {
-                        None => early_error(
-                            error_format,
+                        None => handler.early_error(
                             format!(
                                 "{0} option `{1}` requires {2} ({3} {1}=<value>)",
                                 outputname, key, type_desc, prefix
                             ),
                         ),
-                        Some(value) => early_error(
-                            error_format,
+                        Some(value) => handler.early_error(
                             format!(
                                 "incorrect value `{value}` for {outputname} option `{key}` - {type_desc} was expected"
                             ),
@@ -343,7 +342,7 @@ fn build_options<O: Default>(
                     }
                 }
             }
-            None => early_error(error_format, format!("unknown {outputname} option: `{key}`")),
+            None => handler.early_error(format!("unknown {outputname} option: `{key}`")),
         }
     }
     return op;
@@ -372,7 +371,7 @@ mod desc {
     pub const parse_opt_panic_strategy: &str = parse_panic_strategy;
     pub const parse_oom_strategy: &str = "either `panic` or `abort`";
     pub const parse_relro_level: &str = "one of: `full`, `partial`, or `off`";
-    pub const parse_sanitizers: &str = "comma separated list of sanitizers: `address`, `cfi`, `hwaddress`, `kcfi`, `kernel-address`, `leak`, `memory`, `memtag`, `shadow-call-stack`, or `thread`";
+    pub const parse_sanitizers: &str = "comma separated list of sanitizers: `address`, `cfi`, `hwaddress`, `kcfi`, `kernel-address`, `leak`, `memory`, `memtag`, `safestack`, `shadow-call-stack`, or `thread`";
     pub const parse_sanitizer_memory_track_origins: &str = "0, 1, or 2";
     pub const parse_cfguard: &str =
         "either a boolean (`yes`, `no`, `on`, `off`, etc), `checks`, or `nochecks`";
@@ -389,7 +388,7 @@ mod desc {
     pub const parse_unpretty: &str = "`string` or `string=string`";
     pub const parse_treat_err_as_bug: &str = "either no value or a number bigger than 0";
     pub const parse_trait_solver: &str =
-        "one of the supported solver modes (`classic`, `chalk`, or `next`)";
+        "one of the supported solver modes (`classic`, `next`, or `next-coherence`)";
     pub const parse_lto: &str =
         "either a boolean (`yes`, `no`, `on`, `off`, etc), `thin`, `fat`, or omitted";
     pub const parse_linker_plugin_lto: &str =
@@ -413,12 +412,15 @@ mod desc {
     pub const parse_split_dwarf_kind: &str =
         "one of supported split dwarf modes (`split` or `single`)";
     pub const parse_gcc_ld: &str = "one of: no value, `lld`";
+    pub const parse_link_self_contained: &str = "one of: `y`, `yes`, `on`, `n`, `no`, `off`, or a list of enabled (`+` prefix) and disabled (`-` prefix) \
+        components: `crto`, `libc`, `unwind`, `linker`, `sanitizers`, `mingw`";
     pub const parse_stack_protector: &str =
         "one of (`none` (default), `basic`, `strong`, or `all`)";
     pub const parse_branch_protection: &str =
         "a `,` separated combination of `bti`, `b-key`, `pac-ret`, or `leaf`";
     pub const parse_proc_macro_execution_strategy: &str =
         "one of supported execution strategies (`same-thread`, or `cross-thread`)";
+    pub const parse_dump_solver_proof_tree: &str = "one of: `always`, `on-request`, `on-error`";
 }
 
 mod parse {
@@ -694,6 +696,7 @@ mod parse {
                     "shadow-call-stack" => SanitizerSet::SHADOWCALLSTACK,
                     "thread" => SanitizerSet::THREAD,
                     "hwaddress" => SanitizerSet::HWADDRESS,
+                    "safestack" => SanitizerSet::SAFESTACK,
                     _ => return false,
                 }
             }
@@ -983,8 +986,8 @@ mod parse {
     pub(crate) fn parse_trait_solver(slot: &mut TraitSolver, v: Option<&str>) -> bool {
         match v {
             Some("classic") => *slot = TraitSolver::Classic,
-            Some("chalk") => *slot = TraitSolver::Chalk,
             Some("next") => *slot = TraitSolver::Next,
+            Some("next-coherence") => *slot = TraitSolver::NextCoherence,
             // default trait solver is subject to change..
             Some("default") => *slot = TraitSolver::Classic,
             _ => return false,
@@ -1123,6 +1126,34 @@ mod parse {
         }
     }
 
+    pub(crate) fn parse_link_self_contained(slot: &mut LinkSelfContained, v: Option<&str>) -> bool {
+        // Whenever `-C link-self-contained` is passed without a value, it's an opt-in
+        // just like `parse_opt_bool`, the historical value of this flag.
+        //
+        // 1. Parse historical single bool values
+        let s = v.unwrap_or("y");
+        match s {
+            "y" | "yes" | "on" => {
+                slot.set_all_explicitly(true);
+                return true;
+            }
+            "n" | "no" | "off" => {
+                slot.set_all_explicitly(false);
+                return true;
+            }
+            _ => {}
+        }
+
+        // 2. Parse a list of enabled and disabled components.
+        for comp in s.split(",") {
+            if slot.handle_cli_component(comp).is_err() {
+                return false;
+            }
+        }
+
+        true
+    }
+
     pub(crate) fn parse_wasi_exec_model(slot: &mut Option<WasiExecModel>, v: Option<&str>) -> bool {
         match v {
             Some("command") => *slot = Some(WasiExecModel::Command),
@@ -1209,6 +1240,19 @@ mod parse {
         };
         true
     }
+
+    pub(crate) fn parse_dump_solver_proof_tree(
+        slot: &mut DumpSolverProofTree,
+        v: Option<&str>,
+    ) -> bool {
+        match v {
+            None | Some("always") => *slot = DumpSolverProofTree::Always,
+            Some("never") => *slot = DumpSolverProofTree::Never,
+            Some("on-error") => *slot = DumpSolverProofTree::OnError,
+            _ => return false,
+        };
+        true
+    }
 }
 
 options! {
@@ -1266,9 +1310,9 @@ options! {
     #[rustc_lint_opt_deny_field_access("use `Session::link_dead_code` instead of this field")]
     link_dead_code: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "keep dead code at link time (useful for code coverage) (default: no)"),
-    link_self_contained: Option<bool> = (None, parse_opt_bool, [UNTRACKED],
+    link_self_contained: LinkSelfContained = (LinkSelfContained::default(), parse_link_self_contained, [UNTRACKED],
         "control whether to link Rust provided C objects/libraries or rely
-        on C toolchain installed in the system"),
+        on a C toolchain or linker installed in the system"),
     linker: Option<PathBuf> = (None, parse_opt_pathbuf, [UNTRACKED],
         "system linker to link outputs with"),
     linker_flavor: Option<LinkerFlavorCli> = (None, parse_linker_flavor, [UNTRACKED],
@@ -1315,7 +1359,7 @@ options! {
         "control generation of position-independent code (PIC) \
         (`rustc --print relocation-models` for details)"),
     remark: Passes = (Passes::Some(Vec::new()), parse_passes, [UNTRACKED],
-        "print remarks for these optimization passes (space separated, or \"all\")"),
+        "output remarks for these optimization passes (space separated, or \"all\")"),
     rpath: bool = (false, parse_bool, [UNTRACKED],
         "set rpath values in libs/exes (default: no)"),
     save_temps: bool = (false, parse_bool, [UNTRACKED],
@@ -1371,8 +1415,6 @@ options! {
         "set options for branch target identification and pointer authentication on AArch64"),
     cf_protection: CFProtection = (CFProtection::None, parse_cfprotection, [TRACKED],
         "instrument control-flow architecture protection"),
-    cgu_partitioning_strategy: Option<String> = (None, parse_opt_string, [TRACKED],
-        "the codegen unit partitioning strategy to use"),
     codegen_backend: Option<String> = (None, parse_opt_string, [TRACKED],
         "the backend to use"),
     combine_cgu: bool = (false, parse_bool, [TRACKED],
@@ -1436,6 +1478,11 @@ options! {
         "output statistics about monomorphization collection"),
     dump_mono_stats_format: DumpMonoStatsFormat = (DumpMonoStatsFormat::Markdown, parse_dump_mono_stats, [UNTRACKED],
         "the format to use for -Z dump-mono-stats (`markdown` (default) or `json`)"),
+    dump_solver_proof_tree: DumpSolverProofTree = (DumpSolverProofTree::Never, parse_dump_solver_proof_tree, [UNTRACKED],
+        "dump a proof tree for every goal evaluated by the new trait solver. If the flag is specified without any options after it
+        then it defaults to `always`. If the flag is not specified at all it defaults to `on-request`."),
+    dump_solver_proof_tree_use_cache: Option<bool> = (None, parse_opt_bool, [UNTRACKED],
+        "determines whether dumped proof trees use the global cache"),
     dwarf_version: Option<u32> = (None, parse_opt_number, [TRACKED],
         "version of DWARF debug information to emit (default: 2 or 4, depending on platform)"),
     dylib_lto: bool = (false, parse_bool, [UNTRACKED],
@@ -1558,14 +1605,14 @@ options! {
         "use like `-Zmir-enable-passes=+DestinationPropagation,-InstSimplify`. Forces the specified passes to be \
         enabled, overriding all other checks. Passes that are not specified are enabled or \
         disabled by other flags as usual."),
+    mir_include_spans: bool = (false, parse_bool, [UNTRACKED],
+        "use line numbers relative to the function in mir pretty printing"),
     mir_keep_place_mention: bool = (false, parse_bool, [TRACKED],
         "keep place mention MIR statements, interpreted e.g., by miri; implies -Zmir-opt-level=0 \
         (default: no)"),
     #[rustc_lint_opt_deny_field_access("use `Session::mir_opt_level` instead of this field")]
     mir_opt_level: Option<usize> = (None, parse_opt_number, [TRACKED],
         "MIR optimization level (0-4; default: 1 in non optimized builds and 2 in optimized builds)"),
-    mir_pretty_relative_line_numbers: bool = (false, parse_bool, [UNTRACKED],
-        "use line numbers relative to the function in mir pretty printing"),
     move_size_limit: Option<usize> = (None, parse_opt_number, [TRACKED],
         "the size at which the `large_assignments` lint starts to be emitted"),
     mutable_noalias: bool = (true, parse_bool, [TRACKED],
@@ -1611,7 +1658,7 @@ options! {
     plt: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "whether to use the PLT when calling into shared libraries;
         only has effect for PIC code on systems with ELF binaries
-        (default: PLT is disabled if full relro is enabled)"),
+        (default: PLT is disabled if full relro is enabled on x86_64)"),
     polonius: bool = (false, parse_bool, [TRACKED],
         "enable polonius-based borrow-checker (default: no)"),
     polymorphize: bool = (false, parse_bool, [TRACKED],
@@ -1632,6 +1679,8 @@ options! {
         "print the result of the monomorphization collection pass"),
     print_type_sizes: bool = (false, parse_bool, [UNTRACKED],
         "print layout information for each type encountered (default: no)"),
+    print_vtable_sizes: bool = (false, parse_bool, [UNTRACKED],
+        "print size comparison between old and new vtable layouts (default: no)"),
     proc_macro_backtrace: bool = (false, parse_bool, [UNTRACKED],
          "show backtraces for panics during proc-macro execution (default: no)"),
     proc_macro_execution_strategy: ProcMacroExecutionStrategy = (ProcMacroExecutionStrategy::SameThread,
@@ -1658,6 +1707,9 @@ options! {
         "choose which RELRO level to use"),
     remap_cwd_prefix: Option<PathBuf> = (None, parse_opt_pathbuf, [TRACKED],
         "remap paths under the current working directory to this path prefix"),
+    remark_dir: Option<PathBuf> = (None, parse_opt_pathbuf, [UNTRACKED],
+        "directory into which to write optimization remarks (if not specified, they will be \
+written to standard error output)"),
     report_delayed_bugs: bool = (false, parse_bool, [TRACKED],
         "immediately print bugs registered with `delay_span_bug` (default: no)"),
     sanitizer: SanitizerSet = (SanitizerSet::empty(), parse_sanitizers, [TRACKED],
diff --git a/compiler/rustc_session/src/output.rs b/compiler/rustc_session/src/output.rs
index fdb9fae44..2088744bc 100644
--- a/compiler/rustc_session/src/output.rs
+++ b/compiler/rustc_session/src/output.rs
@@ -1,5 +1,5 @@
 //! Related to out filenames of compilation (e.g. save analysis, binaries).
-use crate::config::{CrateType, Input, OutputFilenames, OutputType};
+use crate::config::{CrateType, Input, OutFileName, OutputFilenames, OutputType};
 use crate::errors::{
     CrateNameDoesNotMatch, CrateNameEmpty, CrateNameInvalid, FileIsNotWriteable,
     InvalidCharacterInCrateName,
@@ -8,14 +8,14 @@ use crate::Session;
 use rustc_ast::{self as ast, attr};
 use rustc_span::symbol::sym;
 use rustc_span::{Span, Symbol};
-use std::path::{Path, PathBuf};
+use std::path::Path;
 
 pub fn out_filename(
     sess: &Session,
     crate_type: CrateType,
     outputs: &OutputFilenames,
     crate_name: Symbol,
-) -> PathBuf {
+) -> OutFileName {
     let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
     let out_filename = outputs
         .outputs
@@ -24,7 +24,9 @@ pub fn out_filename(
         .or_else(|| outputs.single_output_file.clone())
         .unwrap_or(default_filename);
 
-    check_file_is_writeable(&out_filename, sess);
+    if let OutFileName::Real(ref path) = out_filename {
+        check_file_is_writeable(path, sess);
+    }
 
     out_filename
 }
@@ -112,7 +114,7 @@ pub fn filename_for_metadata(
     sess: &Session,
     crate_name: Symbol,
     outputs: &OutputFilenames,
-) -> PathBuf {
+) -> OutFileName {
     // If the command-line specified the path, use that directly.
     if let Some(Some(out_filename)) = sess.opts.output_types.get(&OutputType::Metadata) {
         return out_filename.clone();
@@ -120,12 +122,13 @@ pub fn filename_for_metadata(
 
     let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
 
-    let out_filename = outputs
-        .single_output_file
-        .clone()
-        .unwrap_or_else(|| outputs.out_directory.join(&format!("lib{libname}.rmeta")));
+    let out_filename = outputs.single_output_file.clone().unwrap_or_else(|| {
+        OutFileName::Real(outputs.out_directory.join(&format!("lib{libname}.rmeta")))
+    });
 
-    check_file_is_writeable(&out_filename, sess);
+    if let OutFileName::Real(ref path) = out_filename {
+        check_file_is_writeable(path, sess);
+    }
 
     out_filename
 }
@@ -135,23 +138,33 @@ pub fn filename_for_input(
     crate_type: CrateType,
     crate_name: Symbol,
     outputs: &OutputFilenames,
-) -> PathBuf {
+) -> OutFileName {
     let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
 
     match crate_type {
-        CrateType::Rlib => outputs.out_directory.join(&format!("lib{libname}.rlib")),
+        CrateType::Rlib => {
+            OutFileName::Real(outputs.out_directory.join(&format!("lib{libname}.rlib")))
+        }
         CrateType::Cdylib | CrateType::ProcMacro | CrateType::Dylib => {
             let (prefix, suffix) = (&sess.target.dll_prefix, &sess.target.dll_suffix);
-            outputs.out_directory.join(&format!("{prefix}{libname}{suffix}"))
+            OutFileName::Real(outputs.out_directory.join(&format!("{prefix}{libname}{suffix}")))
         }
         CrateType::Staticlib => {
             let (prefix, suffix) = (&sess.target.staticlib_prefix, &sess.target.staticlib_suffix);
-            outputs.out_directory.join(&format!("{prefix}{libname}{suffix}"))
+            OutFileName::Real(outputs.out_directory.join(&format!("{prefix}{libname}{suffix}")))
         }
         CrateType::Executable => {
             let suffix = &sess.target.exe_suffix;
             let out_filename = outputs.path(OutputType::Exe);
-            if suffix.is_empty() { out_filename } else { out_filename.with_extension(&suffix[1..]) }
+            if let OutFileName::Real(ref path) = out_filename {
+                if suffix.is_empty() {
+                    out_filename
+                } else {
+                    OutFileName::Real(path.with_extension(&suffix[1..]))
+                }
+            } else {
+                out_filename
+            }
         }
     }
 }
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 7b396dde9..194f7201f 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -51,13 +51,6 @@ impl GatedSpans {
         debug_assert_eq!(span, removed_span);
     }
 
-    /// Is the provided `feature` gate ungated currently?
-    ///
-    /// Using this is discouraged unless you have a really good reason to.
-    pub fn is_ungated(&self, feature: Symbol) -> bool {
-        self.spans.borrow().get(&feature).map_or(true, |spans| spans.is_empty())
-    }
-
     /// Prepend the given set of `spans` onto the set in `self`.
     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
         let mut inner = self.spans.borrow_mut();
@@ -84,6 +77,7 @@ impl SymbolGallery {
 
 /// Construct a diagnostic for a language feature error due to the given `span`.
 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
+#[track_caller]
 pub fn feature_err(
     sess: &ParseSess,
     feature: Symbol,
@@ -123,7 +117,7 @@ pub fn feature_err_issue(
 /// Construct a future incompatibility diagnostic for a feature gate.
 ///
 /// This diagnostic is only a warning and *does not cause compilation to fail*.
-pub fn feature_warn(sess: &ParseSess, feature: Symbol, span: Span, explain: &str) {
+pub fn feature_warn(sess: &ParseSess, feature: Symbol, span: Span, explain: &'static str) {
     feature_warn_issue(sess, feature, span, GateIssue::Language, explain);
 }
 
@@ -140,7 +134,7 @@ pub fn feature_warn_issue(
     feature: Symbol,
     span: Span,
     issue: GateIssue,
-    explain: &str,
+    explain: &'static str,
 ) {
     let mut err = sess.span_diagnostic.struct_span_warn(span, explain);
     add_feature_diagnostics_for_issue(&mut err, sess, feature, issue);
diff --git a/compiler/rustc_session/src/search_paths.rs b/compiler/rustc_session/src/search_paths.rs
index 56a6b6f3b..07e78d176 100644
--- a/compiler/rustc_session/src/search_paths.rs
+++ b/compiler/rustc_session/src/search_paths.rs
@@ -1,5 +1,5 @@
 use crate::filesearch::make_target_lib_path;
-use crate::{config, early_error};
+use crate::EarlyErrorHandler;
 use std::path::{Path, PathBuf};
 
 #[derive(Clone, Debug)]
@@ -46,7 +46,7 @@ impl PathKind {
 }
 
 impl SearchPath {
-    pub fn from_cli_opt(path: &str, output: config::ErrorOutputType) -> Self {
+    pub fn from_cli_opt(handler: &EarlyErrorHandler, path: &str) -> Self {
         let (kind, path) = if let Some(stripped) = path.strip_prefix("native=") {
             (PathKind::Native, stripped)
         } else if let Some(stripped) = path.strip_prefix("crate=") {
@@ -61,7 +61,7 @@ impl SearchPath {
             (PathKind::All, path)
         };
         if path.is_empty() {
-            early_error(output, "empty search path given via `-L`");
+            handler.early_error("empty search path given via `-L`");
         }
 
         let dir = PathBuf::from(path);
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index bbe52dbce..5be122ffb 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -1,8 +1,10 @@
 use crate::cgu_reuse_tracker::CguReuseTracker;
 use crate::code_stats::CodeStats;
 pub use crate::code_stats::{DataTypeKind, FieldInfo, FieldKind, SizeKind, VariantInfo};
-use crate::config::Input;
-use crate::config::{self, CrateType, InstrumentCoverage, OptLevel, OutputType, SwitchWithOptPath};
+use crate::config::{
+    self, CrateType, InstrumentCoverage, OptLevel, OutFileName, OutputType, SwitchWithOptPath,
+};
+use crate::config::{ErrorOutputType, Input};
 use crate::errors;
 use crate::parse::{add_feature_diagnostics, ParseSess};
 use crate::search_paths::{PathKind, SearchPath};
@@ -23,7 +25,7 @@ use rustc_errors::json::JsonEmitter;
 use rustc_errors::registry::Registry;
 use rustc_errors::{
     error_code, fallback_fluent_bundle, DiagnosticBuilder, DiagnosticId, DiagnosticMessage,
-    ErrorGuaranteed, FluentBundle, IntoDiagnostic, LazyFallbackBundle, MultiSpan, Noted,
+    ErrorGuaranteed, FluentBundle, Handler, IntoDiagnostic, LazyFallbackBundle, MultiSpan, Noted,
     TerminalUrl,
 };
 use rustc_macros::HashStable_Generic;
@@ -128,14 +130,12 @@ pub struct Limits {
     pub move_size_limit: Limit,
     /// The maximum length of types during monomorphization.
     pub type_length_limit: Limit,
-    /// The maximum blocks a const expression can evaluate.
-    pub const_eval_limit: Limit,
 }
 
 pub struct CompilerIO {
     pub input: Input,
     pub output_dir: Option<PathBuf>,
-    pub output_file: Option<PathBuf>,
+    pub output_file: Option<OutFileName>,
     pub temps_dir: Option<PathBuf>,
 }
 
@@ -234,6 +234,27 @@ pub enum MetadataKind {
     Compressed,
 }
 
+#[derive(Clone, Copy)]
+pub enum CodegenUnits {
+    /// Specified by the user. In this case we try fairly hard to produce the
+    /// number of CGUs requested.
+    User(usize),
+
+    /// A default value, i.e. not specified by the user. In this case we take
+    /// more liberties about CGU formation, e.g. avoid producing very small
+    /// CGUs.
+    Default(usize),
+}
+
+impl CodegenUnits {
+    pub fn as_usize(self) -> usize {
+        match self {
+            CodegenUnits::User(n) => n,
+            CodegenUnits::Default(n) => n,
+        }
+    }
+}
+
 impl Session {
     pub fn miri_unleashed_feature(&self, span: Span, feature_gate: Option<Symbol>) {
         self.miri_unleashed_features.lock().push((span, feature_gate));
@@ -988,11 +1009,11 @@ impl Session {
         self.edition().rust_2024()
     }
 
-    /// Returns `true` if we cannot skip the PLT for shared library calls.
+    /// Returns `true` if we should use the PLT for shared library calls.
     pub fn needs_plt(&self) -> bool {
-        // Check if the current target usually needs PLT to be enabled.
+        // Check if the current target usually wants PLT to be enabled.
         // The user can use the command line flag to override it.
-        let needs_plt = self.target.needs_plt;
+        let want_plt = self.target.plt_by_default;
 
         let dbg_opts = &self.opts.unstable_opts;
 
@@ -1004,8 +1025,8 @@ impl Session {
         let full_relro = RelroLevel::Full == relro_level;
 
         // If user didn't explicitly forced us to use / skip the PLT,
-        // then try to skip it where possible.
-        dbg_opts.plt.unwrap_or(needs_plt || !full_relro)
+        // then use it unless the target doesn't want it by default or the full relro forces it on.
+        dbg_opts.plt.unwrap_or(want_plt || !full_relro)
     }
 
     /// Checks if LLVM lifetime markers should be emitted.
@@ -1104,7 +1125,7 @@ impl Session {
 
         // If there's only one codegen unit and LTO isn't enabled then there's
         // no need for ThinLTO so just return false.
-        if self.codegen_units() == 1 {
+        if self.codegen_units().as_usize() == 1 {
             return config::Lto::No;
         }
 
@@ -1206,19 +1227,19 @@ impl Session {
 
     /// Returns the number of codegen units that should be used for this
     /// compilation
-    pub fn codegen_units(&self) -> usize {
+    pub fn codegen_units(&self) -> CodegenUnits {
         if let Some(n) = self.opts.cli_forced_codegen_units {
-            return n;
+            return CodegenUnits::User(n);
         }
         if let Some(n) = self.target.default_codegen_units {
-            return n as usize;
+            return CodegenUnits::Default(n as usize);
         }
 
         // If incremental compilation is turned on, we default to a high number
         // codegen units in order to reduce the "collateral damage" small
         // changes cause.
         if self.opts.incremental.is_some() {
-            return 256;
+            return CodegenUnits::Default(256);
         }
 
         // Why is 16 codegen units the default all the time?
@@ -1271,7 +1292,7 @@ impl Session {
         // As a result 16 was chosen here! Mostly because it was a power of 2
         // and most benchmarks agreed it was roughly a local optimum. Not very
         // scientific.
-        16
+        CodegenUnits::Default(16)
     }
 
     pub fn teach(&self, code: &DiagnosticId) -> bool {
@@ -1361,6 +1382,7 @@ fn default_emitter(
 // JUSTIFICATION: literally session construction
 #[allow(rustc::bad_opt_access)]
 pub fn build_session(
+    handler: &EarlyErrorHandler,
     sopts: config::Options,
     io: CompilerIO,
     bundle: Option<Lrc<rustc_errors::FluentBundle>>,
@@ -1387,13 +1409,12 @@ pub fn build_session(
         None => filesearch::get_or_default_sysroot().expect("Failed finding sysroot"),
     };
 
-    let target_cfg = config::build_target_config(&sopts, target_override, &sysroot);
+    let target_cfg = config::build_target_config(handler, &sopts, target_override, &sysroot);
     let host_triple = TargetTriple::from_triple(config::host_triple());
-    let (host, target_warnings) = Target::search(&host_triple, &sysroot).unwrap_or_else(|e| {
-        early_error(sopts.error_format, format!("Error loading host specification: {e}"))
-    });
+    let (host, target_warnings) = Target::search(&host_triple, &sysroot)
+        .unwrap_or_else(|e| handler.early_error(format!("Error loading host specification: {e}")));
     for warning in target_warnings.warning_messages() {
-        early_warn(sopts.error_format, warning)
+        handler.early_warn(warning)
     }
 
     let loader = file_loader.unwrap_or_else(|| Box::new(RealFileLoader));
@@ -1435,7 +1456,7 @@ pub fn build_session(
         match profiler {
             Ok(profiler) => Some(Arc::new(profiler)),
             Err(e) => {
-                early_warn(sopts.error_format, format!("failed to create profiler: {e}"));
+                handler.early_warn(format!("failed to create profiler: {e}"));
                 None
             }
         }
@@ -1675,6 +1696,13 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
     if sess.opts.unstable_opts.instrument_xray.is_some() && !sess.target.options.supports_xray {
         sess.emit_err(errors::InstrumentationNotSupported { us: "XRay".to_string() });
     }
+
+    if let Some(flavor) = sess.opts.cg.linker_flavor {
+        if let Some(compatible_list) = sess.target.linker_flavor.check_compatibility(flavor) {
+            let flavor = flavor.desc();
+            sess.emit_err(errors::IncompatibleLinkerFlavor { flavor, compatible_list });
+        }
+    }
 }
 
 /// Holds data on the current incremental compilation session, if there is one.
@@ -1695,7 +1723,64 @@ pub enum IncrCompSession {
     InvalidBecauseOfErrors { session_directory: PathBuf },
 }
 
-fn early_error_handler(output: config::ErrorOutputType) -> rustc_errors::Handler {
+/// A wrapper around an [`Handler`] that is used for early error emissions.
+pub struct EarlyErrorHandler {
+    handler: Handler,
+}
+
+impl EarlyErrorHandler {
+    pub fn new(output: ErrorOutputType) -> Self {
+        let emitter = mk_emitter(output);
+        Self { handler: rustc_errors::Handler::with_emitter(true, None, emitter) }
+    }
+
+    pub fn abort_if_errors(&self) {
+        self.handler.abort_if_errors()
+    }
+
+    /// Swap out the underlying handler once we acquire the user's preference on error emission
+    /// format. Any errors prior to that will cause an abort and all stashed diagnostics of the
+    /// previous handler will be emitted.
+    pub fn abort_if_error_and_set_error_format(&mut self, output: ErrorOutputType) {
+        self.handler.abort_if_errors();
+
+        let emitter = mk_emitter(output);
+        self.handler = Handler::with_emitter(true, None, emitter);
+    }
+
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    pub fn early_note(&self, msg: impl Into<DiagnosticMessage>) {
+        self.handler.struct_note_without_error(msg).emit()
+    }
+
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    pub fn early_help(&self, msg: impl Into<DiagnosticMessage>) {
+        self.handler.struct_help(msg).emit()
+    }
+
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    #[must_use = "ErrorGuaranteed must be returned from `run_compiler` in order to exit with a non-zero status code"]
+    pub fn early_error_no_abort(&self, msg: impl Into<DiagnosticMessage>) -> ErrorGuaranteed {
+        self.handler.struct_err(msg).emit()
+    }
+
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    pub fn early_error(&self, msg: impl Into<DiagnosticMessage>) -> ! {
+        self.handler.struct_fatal(msg).emit()
+    }
+
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    pub fn early_warn(&self, msg: impl Into<DiagnosticMessage>) {
+        self.handler.struct_warn(msg).emit()
+    }
+}
+
+fn mk_emitter(output: ErrorOutputType) -> Box<dyn Emitter + sync::Send + 'static> {
     // FIXME(#100717): early errors aren't translated at the moment, so this is fine, but it will
     // need to reference every crate that might emit an early error for translation to work.
     let fallback_bundle =
@@ -1727,27 +1812,5 @@ fn early_error_handler(output: config::ErrorOutputType) -> rustc_errors::Handler
             TerminalUrl::No,
         )),
     };
-    rustc_errors::Handler::with_emitter(true, None, emitter)
-}
-
-#[allow(rustc::untranslatable_diagnostic)]
-#[allow(rustc::diagnostic_outside_of_impl)]
-#[must_use = "ErrorGuaranteed must be returned from `run_compiler` in order to exit with a non-zero status code"]
-pub fn early_error_no_abort(
-    output: config::ErrorOutputType,
-    msg: impl Into<DiagnosticMessage>,
-) -> ErrorGuaranteed {
-    early_error_handler(output).struct_err(msg).emit()
-}
-
-#[allow(rustc::untranslatable_diagnostic)]
-#[allow(rustc::diagnostic_outside_of_impl)]
-pub fn early_error(output: config::ErrorOutputType, msg: impl Into<DiagnosticMessage>) -> ! {
-    early_error_handler(output).struct_fatal(msg).emit()
-}
-
-#[allow(rustc::untranslatable_diagnostic)]
-#[allow(rustc::diagnostic_outside_of_impl)]
-pub fn early_warn(output: config::ErrorOutputType, msg: impl Into<DiagnosticMessage>) {
-    early_error_handler(output).struct_warn(msg).emit()
+    emitter
 }