Merging debian version 1.65.0+dfsg1-2.

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

12 files changed, 613 insertions, 175 deletions

diff --git a/compiler/rustc_session/Cargo.toml b/compiler/rustc_session/Cargo.toml
index 37cfc4a0d..6b1eaa4d3 100644
--- a/compiler/rustc_session/Cargo.toml
+++ b/compiler/rustc_session/Cargo.toml
@@ -15,6 +15,5 @@ rustc_serialize = { path = "../rustc_serialize" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_span = { path = "../rustc_span" }
 rustc_fs_util = { path = "../rustc_fs_util" }
-num_cpus = "1.0"
 rustc_ast = { path = "../rustc_ast" }
 rustc_lint_defs = { path = "../rustc_lint_defs" }
diff --git a/compiler/rustc_session/src/cgu_reuse_tracker.rs b/compiler/rustc_session/src/cgu_reuse_tracker.rs
index dd64e8ab7..2336d9936 100644
--- a/compiler/rustc_session/src/cgu_reuse_tracker.rs
+++ b/compiler/rustc_session/src/cgu_reuse_tracker.rs
@@ -2,10 +2,14 @@
 //! compilation. This is used for incremental compilation tests and debug
 //! output.
 
+use crate::errors::{CguNotRecorded, IncorrectCguReuseType};
+use crate::Session;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
 use rustc_span::{Span, Symbol};
+use std::borrow::Cow;
+use std::fmt::{self};
 use std::sync::{Arc, Mutex};
-use tracing::debug;
 
 #[derive(Copy, Clone, Debug, PartialEq, PartialOrd)]
 pub enum CguReuse {
@@ -14,6 +18,22 @@ pub enum CguReuse {
     PostLto,
 }
 
+impl fmt::Display for CguReuse {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            CguReuse::No => write!(f, "No"),
+            CguReuse::PreLto => write!(f, "PreLto "),
+            CguReuse::PostLto => write!(f, "PostLto "),
+        }
+    }
+}
+
+impl IntoDiagnosticArg for CguReuse {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::Owned(self.to_string()))
+    }
+}
+
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub enum ComparisonKind {
     Exact,
@@ -84,7 +104,7 @@ impl CguReuseTracker {
         }
     }
 
-    pub fn check_expected_reuse(&self, diag: &rustc_errors::Handler) {
+    pub fn check_expected_reuse(&self, sess: &Session) {
         if let Some(ref data) = self.data {
             let data = data.lock().unwrap();
 
@@ -98,19 +118,17 @@ impl CguReuseTracker {
                     };
 
                     if error {
-                        let at_least = if at_least { "at least " } else { "" };
-                        let msg = format!(
-                            "CGU-reuse for `{cgu_user_name}` is `{actual_reuse:?}` but \
-                                           should be {at_least}`{expected_reuse:?}`"
-                        );
-                        diag.span_err(error_span.0, &msg);
+                        let at_least = if at_least { 1 } else { 0 };
+                        IncorrectCguReuseType {
+                            span: error_span.0,
+                            cgu_user_name: &cgu_user_name,
+                            actual_reuse,
+                            expected_reuse,
+                            at_least,
+                        };
                     }
                 } else {
-                    let msg = format!(
-                        "CGU-reuse for `{cgu_user_name}` (mangled: `{cgu_name}`) was \
-                                       not recorded"
-                    );
-                    diag.span_fatal(error_span.0, &msg)
+                    sess.emit_fatal(CguNotRecorded { cgu_user_name, cgu_name });
                 }
             }
         }
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 6a8298605..8bb3878fb 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -12,8 +12,8 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 
 use rustc_data_structures::stable_hasher::ToStableHashKey;
 use rustc_target::abi::{Align, TargetDataLayout};
-use rustc_target::spec::{LinkerFlavor, SplitDebuginfo, Target, TargetTriple, TargetWarnings};
-use rustc_target::spec::{PanicStrategy, SanitizerSet, TARGETS};
+use rustc_target::spec::{PanicStrategy, SanitizerSet, SplitDebuginfo};
+use rustc_target::spec::{Target, TargetTriple, TargetWarnings, TARGETS};
 
 use crate::parse::{CrateCheckConfig, CrateConfig};
 use rustc_feature::UnstableFeatures;
@@ -36,6 +36,8 @@ use std::iter::{self, FromIterator};
 use std::path::{Path, PathBuf};
 use std::str::{self, FromStr};
 
+pub mod sigpipe;
+
 /// The different settings that the `-C strip` flag can have.
 #[derive(Clone, Copy, PartialEq, Hash, Debug)]
 pub enum Strip {
@@ -798,7 +800,15 @@ impl UnstableOptions {
 // The type of entry function, so users can have their own entry functions
 #[derive(Copy, Clone, PartialEq, Hash, Debug, HashStable_Generic)]
 pub enum EntryFnType {
-    Main,
+    Main {
+        /// Specifies what to do with `SIGPIPE` before calling `fn main()`.
+        ///
+        /// What values that are valid and what they mean must be in sync
+        /// across rustc and libstd, but we don't want it public in libstd,
+        /// so we take a bit of an unusual approach with simple constants
+        /// and an `include!()`.
+        sigpipe: u8,
+    },
     Start,
 }
 
@@ -888,10 +898,10 @@ fn default_configuration(sess: &Session) -> CrateConfig {
     let max_atomic_width = sess.target.max_atomic_width();
     let atomic_cas = sess.target.atomic_cas;
     let layout = TargetDataLayout::parse(&sess.target).unwrap_or_else(|err| {
-        sess.fatal(&err);
+        sess.emit_fatal(err);
     });
 
-    let mut ret = FxHashSet::default();
+    let mut ret = CrateConfig::default();
     ret.reserve(7); // the minimum number of insertions
     // Target bindings.
     ret.insert((sym::target_os, Some(Symbol::intern(os))));
@@ -949,7 +959,7 @@ fn default_configuration(sess: &Session) -> CrateConfig {
         ret.insert((sym::debug_assertions, None));
     }
     // JUSTIFICATION: before wrapper fn is available
-    #[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+    #[allow(rustc::bad_opt_access)]
     if sess.opts.crate_types.contains(&CrateType::ProcMacro) {
         ret.insert((sym::proc_macro, None));
     }
@@ -2198,7 +2208,7 @@ fn parse_remap_path_prefix(
 }
 
 // JUSTIFICATION: before wrapper fn is available
-#[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+#[allow(rustc::bad_opt_access)]
 pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let color = parse_color(matches);
 
@@ -2379,16 +2389,6 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         }
     }
 
-    if cg.linker_flavor == Some(LinkerFlavor::L4Bender)
-        && !nightly_options::is_unstable_enabled(matches)
-    {
-        early_error(
-            error_format,
-            "`l4-bender` linker flavor is unstable, `-Z unstable-options` \
-             flag must also be passed to explicitly use it",
-        );
-    }
-
     let prints = collect_print_requests(&mut cg, &mut unstable_opts, matches, error_format);
 
     let cg = cg;
@@ -2423,13 +2423,6 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 
     let pretty = parse_pretty(&unstable_opts, error_format);
 
-    if !unstable_opts.unstable_options
-        && !target_triple.triple().contains("apple")
-        && cg.split_debuginfo.is_some()
-    {
-        early_error(error_format, "`-Csplit-debuginfo` is unstable on this platform");
-    }
-
     // Try to find a directory containing the Rust `src`, for more details see
     // the doc comment on the `real_rust_source_base_dir` field.
     let tmp_buf;
@@ -2537,7 +2530,7 @@ fn parse_pretty(unstable_opts: &UnstableOptions, efmt: ErrorOutputType) -> Optio
             ),
         ),
     };
-    tracing::debug!("got unpretty option: {first:?}");
+    debug!("got unpretty option: {first:?}");
     Some(first)
 }
 
diff --git a/compiler/rustc_session/src/config/sigpipe.rs b/compiler/rustc_session/src/config/sigpipe.rs
new file mode 100644
index 000000000..a5c94118a
--- /dev/null
+++ b/compiler/rustc_session/src/config/sigpipe.rs
@@ -0,0 +1,22 @@
+//! NOTE: Keep these constants in sync with `library/std/src/sys/unix/mod.rs`!
+
+/// Do not touch `SIGPIPE`. Use whatever the parent process uses.
+#[allow(dead_code)]
+pub const INHERIT: u8 = 1;
+
+/// Change `SIGPIPE` to `SIG_IGN` so that failed writes results in `EPIPE`
+/// that are eventually converted to `ErrorKind::BrokenPipe`.
+#[allow(dead_code)]
+pub const SIG_IGN: u8 = 2;
+
+/// Change `SIGPIPE` to `SIG_DFL` so that the process is killed when trying
+/// to write to a closed pipe. This is usually the desired behavior for CLI
+/// apps that produce textual output that you want to pipe to other programs
+/// such as `head -n 1`.
+#[allow(dead_code)]
+pub const SIG_DFL: u8 = 3;
+
+/// `SIG_IGN` has been the Rust default since 2014. See
+/// <https://github.com/rust-lang/rust/issues/62569>.
+#[allow(dead_code)]
+pub const DEFAULT: u8 = SIG_IGN;
diff --git a/compiler/rustc_session/src/cstore.rs b/compiler/rustc_session/src/cstore.rs
index c1fd3c7c6..7d4a1e212 100644
--- a/compiler/rustc_session/src/cstore.rs
+++ b/compiler/rustc_session/src/cstore.rs
@@ -68,6 +68,8 @@ pub enum LinkagePreference {
 pub struct NativeLib {
     pub kind: NativeLibKind,
     pub name: Option<Symbol>,
+    /// If packed_bundled_libs enabled, actual filename of library is stored.
+    pub filename: Option<Symbol>,
     pub cfg: Option<ast::MetaItem>,
     pub foreign_module: Option<DefId>,
     pub wasm_import_module: Option<Symbol>,
@@ -81,10 +83,29 @@ impl NativeLib {
     }
 }
 
+/// Different ways that the PE Format can decorate a symbol name.
+/// From <https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-name-type>
+#[derive(Copy, Clone, Debug, Encodable, Decodable, HashStable_Generic, PartialEq, Eq)]
+pub enum PeImportNameType {
+    /// IMPORT_ORDINAL
+    /// Uses the ordinal (i.e., a number) rather than the name.
+    Ordinal(u16),
+    /// Same as IMPORT_NAME
+    /// Name is decorated with all prefixes and suffixes.
+    Decorated,
+    /// Same as IMPORT_NAME_NOPREFIX
+    /// Prefix (e.g., the leading `_` or `@`) is skipped, but suffix is kept.
+    NoPrefix,
+    /// Same as IMPORT_NAME_UNDECORATE
+    /// Prefix (e.g., the leading `_` or `@`) and suffix (the first `@` and all
+    /// trailing characters) are skipped.
+    Undecorated,
+}
+
 #[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
 pub struct DllImport {
     pub name: Symbol,
-    pub ordinal: Option<u16>,
+    pub import_name_type: Option<PeImportNameType>,
     /// Calling convention for the function.
     ///
     /// On x86_64, this is always `DllCallingConvention::C`; on i686, it can be any
@@ -92,6 +113,18 @@ pub struct DllImport {
     pub calling_convention: DllCallingConvention,
     /// Span of import's "extern" declaration; used for diagnostics.
     pub span: Span,
+    /// Is this for a function (rather than a static variable).
+    pub is_fn: bool,
+}
+
+impl DllImport {
+    pub fn ordinal(&self) -> Option<u16> {
+        if let Some(PeImportNameType::Ordinal(ordinal)) = self.import_name_type {
+            Some(ordinal)
+        } else {
+            None
+        }
+    }
 }
 
 /// Calling convention for a function defined in an external library.
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
new file mode 100644
index 000000000..c6596ff24
--- /dev/null
+++ b/compiler/rustc_session/src/errors.rs
@@ -0,0 +1,221 @@
+use std::num::NonZeroU32;
+
+use crate::cgu_reuse_tracker::CguReuse;
+use crate::{self as rustc_session, SessionDiagnostic};
+use rustc_errors::{fluent, DiagnosticBuilder, ErrorGuaranteed, Handler, MultiSpan};
+use rustc_macros::SessionDiagnostic;
+use rustc_span::{Span, Symbol};
+use rustc_target::abi::TargetDataLayoutErrors;
+use rustc_target::spec::{SplitDebuginfo, StackProtector, TargetTriple};
+
+#[derive(SessionDiagnostic)]
+#[diag(session::incorrect_cgu_reuse_type)]
+pub struct IncorrectCguReuseType<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub cgu_user_name: &'a str,
+    pub actual_reuse: CguReuse,
+    pub expected_reuse: CguReuse,
+    pub at_least: u8,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::cgu_not_recorded)]
+pub struct CguNotRecorded<'a> {
+    pub cgu_user_name: &'a str,
+    pub cgu_name: &'a str,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::feature_gate_error, code = "E0658")]
+pub struct FeatureGateError<'a> {
+    #[primary_span]
+    pub span: MultiSpan,
+    pub explain: &'a str,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[note(session::feature_diagnostic_for_issue)]
+pub struct FeatureDiagnosticForIssue {
+    pub n: NonZeroU32,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[help(session::feature_diagnostic_help)]
+pub struct FeatureDiagnosticHelp {
+    pub feature: Symbol,
+}
+
+impl SessionDiagnostic<'_, !> for TargetDataLayoutErrors<'_> {
+    fn into_diagnostic(self, sess: &Handler) -> DiagnosticBuilder<'_, !> {
+        let mut diag;
+        match self {
+            TargetDataLayoutErrors::InvalidAddressSpace { addr_space, err, cause } => {
+                diag = sess.struct_fatal(fluent::session::target_invalid_address_space);
+                diag.set_arg("addr_space", addr_space);
+                diag.set_arg("cause", cause);
+                diag.set_arg("err", err);
+                diag
+            }
+            TargetDataLayoutErrors::InvalidBits { kind, bit, cause, err } => {
+                diag = sess.struct_fatal(fluent::session::target_invalid_bits);
+                diag.set_arg("kind", kind);
+                diag.set_arg("bit", bit);
+                diag.set_arg("cause", cause);
+                diag.set_arg("err", err);
+                diag
+            }
+            TargetDataLayoutErrors::MissingAlignment { cause } => {
+                diag = sess.struct_fatal(fluent::session::target_missing_alignment);
+                diag.set_arg("cause", cause);
+                diag
+            }
+            TargetDataLayoutErrors::InvalidAlignment { cause, err } => {
+                diag = sess.struct_fatal(fluent::session::target_invalid_alignment);
+                diag.set_arg("cause", cause);
+                diag.set_arg("err", err);
+                diag
+            }
+            TargetDataLayoutErrors::InconsistentTargetArchitecture { dl, target } => {
+                diag = sess.struct_fatal(fluent::session::target_inconsistent_architecture);
+                diag.set_arg("dl", dl);
+                diag.set_arg("target", target);
+                diag
+            }
+            TargetDataLayoutErrors::InconsistentTargetPointerWidth { pointer_size, target } => {
+                diag = sess.struct_fatal(fluent::session::target_inconsistent_pointer_width);
+                diag.set_arg("pointer_size", pointer_size);
+                diag.set_arg("target", target);
+                diag
+            }
+            TargetDataLayoutErrors::InvalidBitsSize { err } => {
+                diag = sess.struct_fatal(fluent::session::target_invalid_bits_size);
+                diag.set_arg("err", err);
+                diag
+            }
+        }
+    }
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::not_circumvent_feature)]
+pub struct NotCircumventFeature;
+
+#[derive(SessionDiagnostic)]
+#[diag(session::linker_plugin_lto_windows_not_supported)]
+pub struct LinkerPluginToWindowsNotSupported;
+
+#[derive(SessionDiagnostic)]
+#[diag(session::profile_use_file_does_not_exist)]
+pub struct ProfileUseFileDoesNotExist<'a> {
+    pub path: &'a std::path::Path,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::profile_sample_use_file_does_not_exist)]
+pub struct ProfileSampleUseFileDoesNotExist<'a> {
+    pub path: &'a std::path::Path,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::target_requires_unwind_tables)]
+pub struct TargetRequiresUnwindTables;
+
+#[derive(SessionDiagnostic)]
+#[diag(session::sanitizer_not_supported)]
+pub struct SanitizerNotSupported {
+    pub us: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::sanitizers_not_supported)]
+pub struct SanitizersNotSupported {
+    pub us: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::cannot_mix_and_match_sanitizers)]
+pub struct CannotMixAndMatchSanitizers {
+    pub first: String,
+    pub second: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::cannot_enable_crt_static_linux)]
+pub struct CannotEnableCrtStaticLinux;
+
+#[derive(SessionDiagnostic)]
+#[diag(session::sanitizer_cfi_enabled)]
+pub struct SanitizerCfiEnabled;
+
+#[derive(SessionDiagnostic)]
+#[diag(session::unstable_virtual_function_elimination)]
+pub struct UnstableVirtualFunctionElimination;
+
+#[derive(SessionDiagnostic)]
+#[diag(session::unsupported_dwarf_version)]
+pub struct UnsupportedDwarfVersion {
+    pub dwarf_version: u32,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::target_stack_protector_not_supported)]
+pub struct StackProtectorNotSupportedForTarget<'a> {
+    pub stack_protector: StackProtector,
+    pub target_triple: &'a TargetTriple,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::split_debuginfo_unstable_platform)]
+pub struct SplitDebugInfoUnstablePlatform {
+    pub debuginfo: SplitDebuginfo,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::file_is_not_writeable)]
+pub struct FileIsNotWriteable<'a> {
+    pub file: &'a std::path::Path,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::crate_name_does_not_match)]
+pub struct CrateNameDoesNotMatch<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub s: &'a str,
+    pub name: Symbol,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::crate_name_invalid)]
+pub struct CrateNameInvalid<'a> {
+    pub s: &'a str,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(session::crate_name_empty)]
+pub struct CrateNameEmpty {
+    #[primary_span]
+    pub span: Option<Span>,
+}
+
+pub struct InvalidCharacterInCrateName<'a> {
+    pub span: Option<Span>,
+    pub character: char,
+    pub crate_name: &'a str,
+}
+
+impl crate::SessionDiagnostic<'_> for InvalidCharacterInCrateName<'_> {
+    fn into_diagnostic(
+        self,
+        sess: &Handler,
+    ) -> rustc_errors::DiagnosticBuilder<'_, ErrorGuaranteed> {
+        let mut diag = sess.struct_err(fluent::session::invalid_character_in_create_name);
+        if let Some(sp) = self.span {
+            diag.set_span(sp);
+        }
+        diag.set_arg("character", self.character);
+        diag.set_arg("crate_name", self.crate_name);
+        diag
+    }
+}
diff --git a/compiler/rustc_session/src/filesearch.rs b/compiler/rustc_session/src/filesearch.rs
index c973e3140..e8edb38f5 100644
--- a/compiler/rustc_session/src/filesearch.rs
+++ b/compiler/rustc_session/src/filesearch.rs
@@ -7,7 +7,6 @@ use std::path::{Path, PathBuf};
 
 use crate::search_paths::{PathKind, SearchPath};
 use rustc_fs_util::fix_windows_verbatim_for_gcc;
-use tracing::debug;
 
 #[derive(Copy, Clone)]
 pub enum FileMatch {
diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index 7353c1ca0..f6bab775e 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -1,6 +1,6 @@
 #![feature(if_let_guard)]
 #![feature(let_chains)]
-#![feature(let_else)]
+#![cfg_attr(bootstrap, feature(let_else))]
 #![feature(min_specialization)]
 #![feature(never_type)]
 #![feature(once_cell)]
@@ -9,9 +9,15 @@
 #![feature(map_many_mut)]
 #![recursion_limit = "256"]
 #![allow(rustc::potential_query_instability)]
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 
 #[macro_use]
 extern crate rustc_macros;
+pub mod errors;
+
+#[macro_use]
+extern crate tracing;
 
 pub mod cgu_reuse_tracker;
 pub mod utils;
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 1827f1c20..d7f1bc0be 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -5,7 +5,7 @@ use crate::lint;
 use crate::search_paths::SearchPath;
 use crate::utils::NativeLib;
 use rustc_errors::LanguageIdentifier;
-use rustc_target::spec::{CodeModel, LinkerFlavor, MergeFunctions, PanicStrategy, SanitizerSet};
+use rustc_target::spec::{CodeModel, LinkerFlavorCli, MergeFunctions, PanicStrategy, SanitizerSet};
 use rustc_target::spec::{
     RelocModel, RelroLevel, SplitDebuginfo, StackProtector, TargetTriple, TlsModel,
 };
@@ -127,11 +127,11 @@ top_level_options!(
     /// `CodegenOptions`, think about how it influences incremental compilation. If in
     /// doubt, specify `[TRACKED]`, which is always "correct" but might lead to
     /// unnecessary re-compilation.
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_ty)]
+    #[rustc_lint_opt_ty]
     pub struct Options {
         /// The crate config requested for the session, which may be combined
         /// with additional crate configurations during the compile process.
-        #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::crate_types` instead of this field"))]
+        #[rustc_lint_opt_deny_field_access("use `Session::crate_types` instead of this field")]
         crate_types: Vec<CrateType> [TRACKED],
         optimize: OptLevel [TRACKED],
         /// Include the `debug_assertions` flag in dependency tracking, since it
@@ -178,9 +178,9 @@ top_level_options!(
         /// what rustc was invoked with, but massaged a bit to agree with
         /// commands like `--emit llvm-ir` which they're often incompatible with
         /// if we otherwise use the defaults of rustc.
-        #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::codegen_units` instead of this field"))]
+        #[rustc_lint_opt_deny_field_access("use `Session::codegen_units` instead of this field")]
         cli_forced_codegen_units: Option<usize> [UNTRACKED],
-        #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::lto` instead of this field"))]
+        #[rustc_lint_opt_deny_field_access("use `Session::lto` instead of this field")]
         cli_forced_thinlto_off: bool [UNTRACKED],
 
         /// Remap source path prefixes in all output (messages, object files, debug, etc.).
@@ -231,7 +231,7 @@ macro_rules! options {
      ),* ,) =>
 (
     #[derive(Clone)]
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_ty)]
+    #[rustc_lint_opt_ty]
     pub struct $struct_name { $( $( #[$attr] )* pub $opt: $t),* }
 
     impl Default for $struct_name {
@@ -282,7 +282,7 @@ macro_rules! options {
 
 impl Options {
     // JUSTIFICATION: defn of the suggested wrapper fn
-    #[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+    #[allow(rustc::bad_opt_access)]
     pub fn time_passes(&self) -> bool {
         self.unstable_opts.time_passes || self.unstable_opts.time
     }
@@ -290,7 +290,7 @@ impl Options {
 
 impl CodegenOptions {
     // JUSTIFICATION: defn of the suggested wrapper fn
-    #[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+    #[allow(rustc::bad_opt_access)]
     pub fn instrument_coverage(&self) -> InstrumentCoverage {
         self.instrument_coverage.unwrap_or(InstrumentCoverage::Off)
     }
@@ -382,7 +382,7 @@ mod desc {
         "either a boolean (`yes`, `no`, `on`, `off`, etc), `checks`, or `nochecks`";
     pub const parse_cfprotection: &str = "`none`|`no`|`n` (default), `branch`, `return`, or `full`|`yes`|`y` (equivalent to `branch` and `return`)";
     pub const parse_strip: &str = "either `none`, `debuginfo`, or `symbols`";
-    pub const parse_linker_flavor: &str = ::rustc_target::spec::LinkerFlavor::one_of();
+    pub const parse_linker_flavor: &str = ::rustc_target::spec::LinkerFlavorCli::one_of();
     pub const parse_optimization_fuel: &str = "crate=integer";
     pub const parse_mir_spanview: &str = "`statement` (default), `terminator`, or `block`";
     pub const parse_instrument_coverage: &str =
@@ -582,7 +582,7 @@ mod parse {
     pub(crate) fn parse_threads(slot: &mut usize, v: Option<&str>) -> bool {
         match v.and_then(|s| s.parse().ok()) {
             Some(0) => {
-                *slot = ::num_cpus::get();
+                *slot = std::thread::available_parallelism().map_or(1, std::num::NonZeroUsize::get);
                 true
             }
             Some(i) => {
@@ -763,8 +763,8 @@ mod parse {
         true
     }
 
-    pub(crate) fn parse_linker_flavor(slot: &mut Option<LinkerFlavor>, v: Option<&str>) -> bool {
-        match v.and_then(LinkerFlavor::from_str) {
+    pub(crate) fn parse_linker_flavor(slot: &mut Option<LinkerFlavorCli>, v: Option<&str>) -> bool {
+        match v.and_then(LinkerFlavorCli::from_str) {
             Some(lf) => *slot = Some(lf),
             _ => return false,
         }
@@ -1091,7 +1091,7 @@ options! {
 
     ar: String = (String::new(), parse_string, [UNTRACKED],
         "this option is deprecated and does nothing"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::code_model` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::code_model` instead of this field")]
     code_model: Option<CodeModel> = (None, parse_code_model, [TRACKED],
         "choose the code model to use (`rustc --print code-models` for details)"),
     codegen_units: Option<usize> = (None, parse_opt_number, [UNTRACKED],
@@ -1111,14 +1111,14 @@ options! {
         "extra data to put in each output filename"),
     force_frame_pointers: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "force use of the frame pointers"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::must_emit_unwind_tables` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::must_emit_unwind_tables` instead of this field")]
     force_unwind_tables: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "force use of unwind tables"),
     incremental: Option<String> = (None, parse_opt_string, [UNTRACKED],
         "enable incremental compilation"),
     inline_threshold: Option<u32> = (None, parse_opt_number, [TRACKED],
         "set the threshold for inlining a function"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::instrument_coverage` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::instrument_coverage` instead of this field")]
     instrument_coverage: Option<InstrumentCoverage> = (None, parse_instrument_coverage, [TRACKED],
         "instrument the generated code to support LLVM source-based code coverage \
         reports (note, the compiler build config must include `profiler = true`); \
@@ -1131,7 +1131,7 @@ options! {
         "a single extra argument to append to the linker invocation (can be used several times)"),
     link_args: Vec<String> = (Vec::new(), parse_list, [UNTRACKED],
         "extra arguments to append to the linker invocation (space separated)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::link_dead_code` instead of this field"))]
+    #[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],
@@ -1139,14 +1139,14 @@ options! {
         on C toolchain installed in the system"),
     linker: Option<PathBuf> = (None, parse_opt_pathbuf, [UNTRACKED],
         "system linker to link outputs with"),
-    linker_flavor: Option<LinkerFlavor> = (None, parse_linker_flavor, [UNTRACKED],
+    linker_flavor: Option<LinkerFlavorCli> = (None, parse_linker_flavor, [UNTRACKED],
         "linker flavor"),
     linker_plugin_lto: LinkerPluginLto = (LinkerPluginLto::Disabled,
         parse_linker_plugin_lto, [TRACKED],
         "generate build artifacts that are compatible with linker-based LTO"),
     llvm_args: Vec<String> = (Vec::new(), parse_list, [TRACKED],
         "a list of arguments to pass to LLVM (space separated)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::lto` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::lto` instead of this field")]
     lto: LtoCli = (LtoCli::Unspecified, parse_lto, [TRACKED],
         "perform LLVM link-time optimizations"),
     metadata: Vec<String> = (Vec::new(), parse_list, [TRACKED],
@@ -1163,10 +1163,10 @@ options! {
         "disable LLVM's SLP vectorization pass"),
     opt_level: String = ("0".to_string(), parse_string, [TRACKED],
         "optimization level (0-3, s, or z; default: 0)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::overflow_checks` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::overflow_checks` instead of this field")]
     overflow_checks: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "use overflow checks for integer arithmetic"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::panic_strategy` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::panic_strategy` instead of this field")]
     panic: Option<PanicStrategy> = (None, parse_opt_panic_strategy, [TRACKED],
         "panic strategy to compile crate with"),
     passes: Vec<String> = (Vec::new(), parse_list, [TRACKED],
@@ -1178,7 +1178,7 @@ options! {
         "compile the program with profiling instrumentation"),
     profile_use: Option<PathBuf> = (None, parse_opt_pathbuf, [TRACKED],
         "use the given `.profdata` file for profile-guided optimization"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::relocation_model` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::relocation_model` instead of this field")]
     relocation_model: Option<RelocModel> = (None, parse_relocation_model, [TRACKED],
         "control generation of position-independent code (PIC) \
         (`rustc --print relocation-models` for details)"),
@@ -1190,7 +1190,7 @@ options! {
         "save all temporary output files during compilation (default: no)"),
     soft_float: bool = (false, parse_bool, [TRACKED],
         "use soft float ABI (*eabihf targets only) (default: no)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::split_debuginfo` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::split_debuginfo` instead of this field")]
     split_debuginfo: Option<SplitDebuginfo> = (None, parse_split_debuginfo, [TRACKED],
         "how to handle split-debuginfo, a platform-specific option"),
     strip: Strip = (Strip::None, parse_strip, [UNTRACKED],
@@ -1226,13 +1226,13 @@ options! {
         "encode MIR of all functions into the crate metadata (default: no)"),
     assume_incomplete_release: bool = (false, parse_bool, [TRACKED],
         "make cfg(version) treat the current version as incomplete (default: no)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::asm_comments` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::asm_comments` instead of this field")]
     asm_comments: bool = (false, parse_bool, [TRACKED],
         "generate comments into the assembly (may change behavior) (default: no)"),
     assert_incr_state: Option<String> = (None, parse_opt_string, [UNTRACKED],
         "assert that the incremental cache is in given state: \
          either `loaded` or `not-loaded`."),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::binary_dep_depinfo` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::binary_dep_depinfo` instead of this field")]
     binary_dep_depinfo: bool = (false, parse_bool, [TRACKED],
         "include artifacts (sysroot, crate dependencies) used during compilation in dep-info \
         (default: no)"),
@@ -1310,7 +1310,9 @@ options! {
         "emit the bc module with thin LTO info (default: yes)"),
     export_executable_symbols: bool = (false, parse_bool, [TRACKED],
         "export symbols from executables, as if they were dynamic libraries"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::fewer_names` instead of this field"))]
+    extra_const_ub_checks: bool = (false, parse_bool, [TRACKED],
+        "turns on more checks to detect const UB, which can be slow (default: no)"),
+    #[rustc_lint_opt_deny_field_access("use `Session::fewer_names` instead of this field")]
     fewer_names: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "reduce memory use by retaining fewer names within compilation artifacts (LLVM-IR) \
         (default: no)"),
@@ -1343,6 +1345,8 @@ options! {
         "hash spans relative to their parent item for incr. comp. (default: no)"),
     incremental_verify_ich: bool = (false, parse_bool, [UNTRACKED],
         "verify incr. comp. hashes of green query instances (default: no)"),
+    inline_llvm: bool = (true, parse_bool, [TRACKED],
+        "enable LLVM inlining (default: yes)"),
     inline_mir: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "enable MIR inlining (default: no)"),
     inline_mir_threshold: Option<usize> = (None, parse_opt_number, [TRACKED],
@@ -1353,7 +1357,7 @@ options! {
         "control whether `#[inline]` functions are in all CGUs"),
     input_stats: bool = (false, parse_bool, [UNTRACKED],
         "gather statistics about the input (default: no)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::instrument_coverage` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::instrument_coverage` instead of this field")]
     instrument_coverage: Option<InstrumentCoverage> = (None, parse_instrument_coverage, [TRACKED],
         "instrument the generated code to support LLVM source-based code coverage \
         reports (note, the compiler build config must include `profiler = true`); \
@@ -1362,7 +1366,7 @@ options! {
         `=except-unused-generics`
         `=except-unused-functions`
         `=off` (default)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::instrument_mcount` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::instrument_mcount` instead of this field")]
     instrument_mcount: bool = (false, parse_bool, [TRACKED],
         "insert function instrument code for mcount-based tracing (default: no)"),
     keep_hygiene_data: bool = (false, parse_bool, [UNTRACKED],
@@ -1386,7 +1390,7 @@ options! {
     merge_functions: Option<MergeFunctions> = (None, parse_merge_functions, [TRACKED],
         "control the operation of the MergeFunctions LLVM pass, taking \
         the same values as the target option of the same name"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::meta_stats` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::meta_stats` instead of this field")]
     meta_stats: bool = (false, parse_bool, [UNTRACKED],
         "gather metadata statistics (default: no)"),
     mir_emit_retag: bool = (false, parse_bool, [TRACKED],
@@ -1398,7 +1402,7 @@ options! {
         disabled by other flags as usual."),
     mir_pretty_relative_line_numbers: bool = (false, parse_bool, [UNTRACKED],
         "use line numbers relative to the function in mir pretty printing"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::mir_opt_level` instead of this field"))]
+    #[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)"),
     move_size_limit: Option<usize> = (None, parse_opt_number, [TRACKED],
@@ -1437,6 +1441,8 @@ options! {
         "pass `-install_name @rpath/...` to the macOS linker (default: no)"),
     diagnostic_width: Option<usize> = (None, parse_opt_number, [UNTRACKED],
         "set the current output width for diagnostic truncation"),
+    packed_bundled_libs: bool = (false, parse_bool, [TRACKED],
+        "change rlib format to store native libraries as archives"),
     panic_abort_tests: bool = (false, parse_bool, [TRACKED],
         "support compiling tests with panic=abort (default: no)"),
     panic_in_drop: PanicStrategy = (PanicStrategy::Unwind, parse_panic_strategy, [TRACKED],
@@ -1465,7 +1471,7 @@ options! {
         See #77382 and #74551."),
     print_fuel: Option<String> = (None, parse_opt_string, [TRACKED],
         "make rustc print the total optimization fuel used by a crate"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::print_llvm_passes` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::print_llvm_passes` instead of this field")]
     print_llvm_passes: bool = (false, parse_bool, [UNTRACKED],
         "print the LLVM optimization passes being run (default: no)"),
     print_mono_items: Option<String> = (None, parse_opt_string, [UNTRACKED],
@@ -1543,7 +1549,7 @@ options! {
         "exclude spans when debug-printing compiler state (default: no)"),
     src_hash_algorithm: Option<SourceFileHashAlgorithm> = (None, parse_src_file_hash, [TRACKED],
         "hash algorithm of source files in debug info (`md5`, `sha1`, or `sha256`)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::stack_protector` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::stack_protector` instead of this field")]
     stack_protector: StackProtector = (StackProtector::None, parse_stack_protector, [TRACKED],
         "control stack smash protection strategy (`rustc --print stack-protector-strategies` for details)"),
     strict_init_checks: bool = (false, parse_bool, [TRACKED],
@@ -1564,7 +1570,7 @@ options! {
     symbol_mangling_version: Option<SymbolManglingVersion> = (None,
         parse_symbol_mangling_version, [TRACKED],
         "which mangling version to use for symbol names ('legacy' (default) or 'v0')"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::teach` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::teach` instead of this field")]
     teach: bool = (false, parse_bool, [TRACKED],
         "show extended diagnostic help (default: no)"),
     temps_dir: Option<String> = (None, parse_opt_string, [UNTRACKED],
@@ -1580,7 +1586,7 @@ options! {
         "emit directionality isolation markers in translated diagnostics"),
     tune_cpu: Option<String> = (None, parse_opt_string, [TRACKED],
         "select processor to schedule for (`rustc --print target-cpus` for details)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::lto` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::lto` instead of this field")]
     thinlto: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "enable ThinLTO when possible"),
     thir_unsafeck: bool = (false, parse_bool, [TRACKED],
@@ -1589,19 +1595,19 @@ options! {
     /// a sequential compiler for now. This'll likely be adjusted
     /// in the future. Note that -Zthreads=0 is the way to get
     /// the num_cpus behavior.
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::threads` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::threads` instead of this field")]
     threads: usize = (1, parse_threads, [UNTRACKED],
         "use a thread pool with N threads"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::time_passes` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::time_passes` instead of this field")]
     time: bool = (false, parse_bool, [UNTRACKED],
         "measure time of rustc processes (default: no)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::time_llvm_passes` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::time_llvm_passes` instead of this field")]
     time_llvm_passes: bool = (false, parse_bool, [UNTRACKED],
         "measure time of each LLVM pass (default: no)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::time_passes` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::time_passes` instead of this field")]
     time_passes: bool = (false, parse_bool, [UNTRACKED],
         "measure time of each rustc pass (default: no)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::tls_model` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::tls_model` instead of this field")]
     tls_model: Option<TlsModel> = (None, parse_tls_model, [TRACKED],
         "choose the TLS model to use (`rustc --print tls-models` for details)"),
     trace_macros: bool = (false, parse_bool, [UNTRACKED],
@@ -1636,17 +1642,17 @@ options! {
         "enable unsound and buggy MIR optimizations (default: no)"),
     /// This name is kind of confusing: Most unstable options enable something themselves, while
     /// this just allows "normal" options to be feature-gated.
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::unstable_options` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::unstable_options` instead of this field")]
     unstable_options: bool = (false, parse_bool, [UNTRACKED],
         "adds unstable command line options to rustc interface (default: no)"),
     use_ctors_section: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "use legacy .ctors section for initializers rather than .init_array"),
     validate_mir: bool = (false, parse_bool, [UNTRACKED],
         "validate MIR after each transformation"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::verbose` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::verbose` instead of this field")]
     verbose: bool = (false, parse_bool, [UNTRACKED],
         "in general, enable more debug printouts (default: no)"),
-    #[cfg_attr(not(bootstrap), rustc_lint_opt_deny_field_access("use `Session::verify_llvm_ir` instead of this field"))]
+    #[rustc_lint_opt_deny_field_access("use `Session::verify_llvm_ir` instead of this field")]
     verify_llvm_ir: bool = (false, parse_bool, [TRACKED],
         "verify LLVM IR (default: no)"),
     virtual_function_elimination: bool = (false, parse_bool, [TRACKED],
diff --git a/compiler/rustc_session/src/output.rs b/compiler/rustc_session/src/output.rs
index e5e6579d7..2511bee46 100644
--- a/compiler/rustc_session/src/output.rs
+++ b/compiler/rustc_session/src/output.rs
@@ -1,5 +1,9 @@
 //! Related to out filenames of compilation (e.g. save analysis, binaries).
 use crate::config::{CrateType, Input, OutputFilenames, OutputType};
+use crate::errors::{
+    CrateNameDoesNotMatch, CrateNameEmpty, CrateNameInvalid, FileIsNotWriteable,
+    InvalidCharacterInCrateName,
+};
 use crate::Session;
 use rustc_ast as ast;
 use rustc_span::symbol::sym;
@@ -30,11 +34,7 @@ pub fn out_filename(
 /// read-only file.  We should be consistent.
 pub fn check_file_is_writeable(file: &Path, sess: &Session) {
     if !is_writeable(file) {
-        sess.fatal(&format!(
-            "output file {} is not writeable -- check its \
-                            permissions",
-            file.display()
-        ));
+        sess.emit_fatal(FileIsNotWriteable { file });
     }
 }
 
@@ -61,11 +61,7 @@ pub fn find_crate_name(sess: &Session, attrs: &[ast::Attribute], input: &Input)
     if let Some(ref s) = sess.opts.crate_name {
         if let Some((attr, name)) = attr_crate_name {
             if name.as_str() != s {
-                let msg = format!(
-                    "`--crate-name` and `#[crate_name]` are \
-                                   required to match, but `{s}` != `{name}`"
-                );
-                sess.span_err(attr.span, &msg);
+                sess.emit_err(CrateNameDoesNotMatch { span: attr.span, s, name });
             }
         }
         return validate(s.clone(), None);
@@ -77,11 +73,7 @@ pub fn find_crate_name(sess: &Session, attrs: &[ast::Attribute], input: &Input)
     if let Input::File(ref path) = *input {
         if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
             if s.starts_with('-') {
-                let msg = format!(
-                    "crate names cannot start with a `-`, but \
-                                   `{s}` has a leading hyphen"
-                );
-                sess.err(&msg);
+                sess.emit_err(CrateNameInvalid { s });
             } else {
                 return validate(s.replace('-', "_"), None);
             }
@@ -94,15 +86,9 @@ pub fn find_crate_name(sess: &Session, attrs: &[ast::Attribute], input: &Input)
 pub fn validate_crate_name(sess: &Session, s: &str, sp: Option<Span>) {
     let mut err_count = 0;
     {
-        let mut say = |s: &str| {
-            match sp {
-                Some(sp) => sess.span_err(sp, s),
-                None => sess.err(s),
-            };
-            err_count += 1;
-        };
         if s.is_empty() {
-            say("crate name must not be empty");
+            err_count += 1;
+            sess.emit_err(CrateNameEmpty { span: sp });
         }
         for c in s.chars() {
             if c.is_alphanumeric() {
@@ -111,7 +97,8 @@ pub fn validate_crate_name(sess: &Session, s: &str, sp: Option<Span>) {
             if c == '_' {
                 continue;
             }
-            say(&format!("invalid character `{c}` in crate name: `{s}`"));
+            err_count += 1;
+            sess.emit_err(InvalidCharacterInCrateName { span: sp, character: c, crate_name: s });
         }
     }
 
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index f31d52147..0389b2a06 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -2,15 +2,18 @@
 //! It also serves as an input to the parser itself.
 
 use crate::config::CheckCfg;
-use crate::lint::{BufferedEarlyLint, BuiltinLintDiagnostics, Lint, LintId};
+use crate::errors::{FeatureDiagnosticForIssue, FeatureDiagnosticHelp, FeatureGateError};
+use crate::lint::{
+    builtin::UNSTABLE_SYNTAX_PRE_EXPANSION, BufferedEarlyLint, BuiltinLintDiagnostics, Lint, LintId,
+};
 use crate::SessionDiagnostic;
 use rustc_ast::node_id::NodeId;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
 use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
 use rustc_errors::{
-    error_code, fallback_fluent_bundle, Applicability, Diagnostic, DiagnosticBuilder,
-    DiagnosticMessage, ErrorGuaranteed, MultiSpan,
+    fallback_fluent_bundle, Applicability, Diagnostic, DiagnosticBuilder, DiagnosticId,
+    DiagnosticMessage, EmissionGuarantee, ErrorGuaranteed, MultiSpan, StashKey,
 };
 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
 use rustc_span::edition::Edition;
@@ -18,11 +21,12 @@ use rustc_span::hygiene::ExpnId;
 use rustc_span::source_map::{FilePathMapping, SourceMap};
 use rustc_span::{Span, Symbol};
 
+use rustc_ast::attr::AttrIdGenerator;
 use std::str;
 
 /// The set of keys (and, optionally, values) that define the compilation
 /// environment of the crate, used to drive conditional compilation.
-pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
+pub type CrateConfig = FxIndexSet<(Symbol, Option<Symbol>)>;
 pub type CrateCheckConfig = CheckCfg<Symbol>;
 
 /// Collected spans during parsing for places where a certain feature was
@@ -101,11 +105,60 @@ pub fn feature_err_issue<'a>(
     issue: GateIssue,
     explain: &str,
 ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
-    let mut err = sess.span_diagnostic.struct_span_err_with_code(span, explain, error_code!(E0658));
+    let span = span.into();
+
+    // Cancel an earlier warning for this same error, if it exists.
+    if let Some(span) = span.primary_span() {
+        sess.span_diagnostic
+            .steal_diagnostic(span, StashKey::EarlySyntaxWarning)
+            .map(|err| err.cancel());
+    }
+
+    let mut err = sess.create_err(FeatureGateError { span, explain });
     add_feature_diagnostics_for_issue(&mut err, sess, feature, issue);
     err
 }
 
+/// 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<'a>(sess: &'a ParseSess, feature: Symbol, span: Span, explain: &str) {
+    feature_warn_issue(sess, feature, span, GateIssue::Language, explain);
+}
+
+/// Construct a future incompatibility diagnostic for a feature gate.
+///
+/// This diagnostic is only a warning and *does not cause compilation to fail*.
+///
+/// This variant allows you to control whether it is a library or language feature.
+/// Almost always, you want to use this for a language feature. If so, prefer `feature_warn`.
+#[allow(rustc::diagnostic_outside_of_impl)]
+#[allow(rustc::untranslatable_diagnostic)]
+pub fn feature_warn_issue<'a>(
+    sess: &'a ParseSess,
+    feature: Symbol,
+    span: Span,
+    issue: GateIssue,
+    explain: &str,
+) {
+    let mut err = sess.span_diagnostic.struct_span_warn(span, explain);
+    add_feature_diagnostics_for_issue(&mut err, sess, feature, issue);
+
+    // Decorate this as a future-incompatibility lint as in rustc_middle::lint::struct_lint_level
+    let lint = UNSTABLE_SYNTAX_PRE_EXPANSION;
+    let future_incompatible = lint.future_incompatible.as_ref().unwrap();
+    err.code(DiagnosticId::Lint {
+        name: lint.name_lower(),
+        has_future_breakage: false,
+        is_force_warn: false,
+    });
+    err.warn(lint.desc);
+    err.note(format!("for more information, see {}", future_incompatible.reference));
+
+    // A later feature_err call can steal and cancel this warning.
+    err.stash(span, StashKey::EarlySyntaxWarning);
+}
+
 /// Adds the diagnostics for a feature to an existing error.
 pub fn add_feature_diagnostics<'a>(err: &mut Diagnostic, sess: &'a ParseSess, feature: Symbol) {
     add_feature_diagnostics_for_issue(err, sess, feature, GateIssue::Language);
@@ -123,14 +176,12 @@ pub fn add_feature_diagnostics_for_issue<'a>(
     issue: GateIssue,
 ) {
     if let Some(n) = find_feature_issue(feature, issue) {
-        err.note(&format!(
-            "see issue #{n} <https://github.com/rust-lang/rust/issues/{n}> for more information"
-        ));
+        err.subdiagnostic(FeatureDiagnosticForIssue { n });
     }
 
     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
     if sess.unstable_features.is_nightly_build() {
-        err.help(&format!("add `#![feature({feature})]` to the crate attributes to enable"));
+        err.subdiagnostic(FeatureDiagnosticHelp { feature });
     }
 }
 
@@ -169,6 +220,8 @@ pub struct ParseSess {
     /// Spans passed to `proc_macro::quote_span`. Each span has a numerical
     /// identifier represented by its position in the vector.
     pub proc_macro_quoted_spans: Lock<Vec<Span>>,
+    /// Used to generate new `AttrId`s. Every `AttrId` is unique.
+    pub attr_id_generator: AttrIdGenerator,
 }
 
 impl ParseSess {
@@ -191,7 +244,7 @@ impl ParseSess {
         Self {
             span_diagnostic: handler,
             unstable_features: UnstableFeatures::from_environment(None),
-            config: FxHashSet::default(),
+            config: FxIndexSet::default(),
             check_config: CrateCheckConfig::default(),
             edition: ExpnId::root().expn_data().edition,
             raw_identifier_spans: Lock::new(Vec::new()),
@@ -207,6 +260,7 @@ impl ParseSess {
             type_ascription_path_suggestions: Default::default(),
             assume_incomplete_release: false,
             proc_macro_quoted_spans: Default::default(),
+            attr_id_generator: AttrIdGenerator::new(),
         }
     }
 
@@ -293,7 +347,7 @@ impl ParseSess {
         &'a self,
         err: impl SessionDiagnostic<'a>,
     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
-        err.into_diagnostic(self)
+        err.into_diagnostic(&self.span_diagnostic)
     }
 
     pub fn emit_err<'a>(&'a self, err: impl SessionDiagnostic<'a>) -> ErrorGuaranteed {
@@ -304,14 +358,27 @@ impl ParseSess {
         &'a self,
         warning: impl SessionDiagnostic<'a, ()>,
     ) -> DiagnosticBuilder<'a, ()> {
-        warning.into_diagnostic(self)
+        warning.into_diagnostic(&self.span_diagnostic)
     }
 
     pub fn emit_warning<'a>(&'a self, warning: impl SessionDiagnostic<'a, ()>) {
         self.create_warning(warning).emit()
     }
 
+    pub fn create_fatal<'a>(
+        &'a self,
+        fatal: impl SessionDiagnostic<'a, !>,
+    ) -> DiagnosticBuilder<'a, !> {
+        fatal.into_diagnostic(&self.span_diagnostic)
+    }
+
+    pub fn emit_fatal<'a>(&'a self, fatal: impl SessionDiagnostic<'a, !>) -> ! {
+        self.create_fatal(fatal).emit()
+    }
+
     #[rustc_lint_diagnostics]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_err(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -320,7 +387,26 @@ impl ParseSess {
     }
 
     #[rustc_lint_diagnostics]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_warn(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         self.span_diagnostic.struct_warn(msg)
     }
+
+    #[rustc_lint_diagnostics]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    #[allow(rustc::untranslatable_diagnostic)]
+    pub fn struct_fatal(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, !> {
+        self.span_diagnostic.struct_fatal(msg)
+    }
+
+    #[rustc_lint_diagnostics]
+    #[allow(rustc::diagnostic_outside_of_impl)]
+    #[allow(rustc::untranslatable_diagnostic)]
+    pub fn struct_diagnostic<G: EmissionGuarantee>(
+        &self,
+        msg: impl Into<DiagnosticMessage>,
+    ) -> DiagnosticBuilder<'_, G> {
+        self.span_diagnostic.struct_diagnostic(msg)
+    }
 }
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 9669287b3..a001f87db 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -2,6 +2,13 @@ use crate::cgu_reuse_tracker::CguReuseTracker;
 use crate::code_stats::CodeStats;
 pub use crate::code_stats::{DataTypeKind, FieldInfo, SizeKind, VariantInfo};
 use crate::config::{self, CrateType, InstrumentCoverage, OptLevel, OutputType, SwitchWithOptPath};
+use crate::errors::{
+    CannotEnableCrtStaticLinux, CannotMixAndMatchSanitizers, LinkerPluginToWindowsNotSupported,
+    NotCircumventFeature, ProfileSampleUseFileDoesNotExist, ProfileUseFileDoesNotExist,
+    SanitizerCfiEnabled, SanitizerNotSupported, SanitizersNotSupported,
+    SplitDebugInfoUnstablePlatform, StackProtectorNotSupportedForTarget,
+    TargetRequiresUnwindTables, UnstableVirtualFunctionElimination, UnsupportedDwarfVersion,
+};
 use crate::parse::{add_feature_diagnostics, ParseSess};
 use crate::search_paths::{PathKind, SearchPath};
 use crate::{filesearch, lint};
@@ -20,8 +27,8 @@ use rustc_errors::emitter::{Emitter, EmitterWriter, HumanReadableErrorType};
 use rustc_errors::json::JsonEmitter;
 use rustc_errors::registry::Registry;
 use rustc_errors::{
-    fallback_fluent_bundle, DiagnosticBuilder, DiagnosticId, DiagnosticMessage, EmissionGuarantee,
-    ErrorGuaranteed, FluentBundle, LazyFallbackBundle, MultiSpan,
+    error_code, fallback_fluent_bundle, DiagnosticBuilder, DiagnosticId, DiagnosticMessage,
+    EmissionGuarantee, ErrorGuaranteed, FluentBundle, Handler, LazyFallbackBundle, MultiSpan,
 };
 use rustc_macros::HashStable_Generic;
 pub use rustc_span::def_id::StableCrateId;
@@ -31,7 +38,7 @@ use rustc_span::{sym, SourceFileHashAlgorithm, Symbol};
 use rustc_target::asm::InlineAsmArch;
 use rustc_target::spec::{CodeModel, PanicStrategy, RelocModel, RelroLevel};
 use rustc_target::spec::{
-    SanitizerSet, SplitDebuginfo, StackProtector, Target, TargetTriple, TlsModel,
+    DebuginfoKind, SanitizerSet, SplitDebuginfo, StackProtector, Target, TargetTriple, TlsModel,
 };
 
 use std::cell::{self, RefCell};
@@ -110,6 +117,12 @@ impl Mul<usize> for Limit {
     }
 }
 
+impl rustc_errors::IntoDiagnosticArg for Limit {
+    fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+        self.to_string().into_diagnostic_arg()
+    }
+}
+
 #[derive(Clone, Copy, Debug, HashStable_Generic)]
 pub struct Limits {
     /// The maximum recursion limit for potentially infinitely recursive
@@ -214,9 +227,9 @@ pub struct PerfStats {
 /// `#[derive(SessionDiagnostic)]` -- see [rustc_macros::SessionDiagnostic].
 #[rustc_diagnostic_item = "SessionDiagnostic"]
 pub trait SessionDiagnostic<'a, T: EmissionGuarantee = ErrorGuaranteed> {
-    /// Write out as a diagnostic out of `sess`.
+    /// Write out as a diagnostic out of `Handler`.
     #[must_use]
-    fn into_diagnostic(self, sess: &'a ParseSess) -> DiagnosticBuilder<'a, T>;
+    fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, T>;
 }
 
 impl Session {
@@ -229,6 +242,9 @@ impl Session {
         if !unleashed_features.is_empty() {
             let mut must_err = false;
             // Create a diagnostic pointing at where things got unleashed.
+            // FIXME(#100717): needs eager translation/lists
+            #[allow(rustc::untranslatable_diagnostic)]
+            #[allow(rustc::diagnostic_outside_of_impl)]
             let mut diag = self.struct_warn("skipping const checks");
             for &(span, feature_gate) in unleashed_features.iter() {
                 // FIXME: `span_label` doesn't do anything, so we use "help" as a hack.
@@ -244,10 +260,7 @@ impl Session {
             // If we should err, make sure we did.
             if must_err && self.has_errors().is_none() {
                 // We have skipped a feature gate, and not run into other errors... reject.
-                self.err(
-                    "`-Zunleash-the-miri-inside-of-you` may not be used to circumvent feature \
-                     gates, except when testing error paths in the CTFE engine",
-                );
+                self.emit_err(NotCircumventFeature);
             }
         }
     }
@@ -284,6 +297,8 @@ impl Session {
     }
 
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_span_warn<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -292,6 +307,8 @@ impl Session {
         self.diagnostic().struct_span_warn(sp, msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_span_warn_with_expectation<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -301,6 +318,8 @@ impl Session {
         self.diagnostic().struct_span_warn_with_expectation(sp, msg, id)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_span_warn_with_code<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -310,10 +329,14 @@ impl Session {
         self.diagnostic().struct_span_warn_with_code(sp, msg, code)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_warn(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         self.diagnostic().struct_warn(msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_warn_with_expectation(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -322,6 +345,8 @@ impl Session {
         self.diagnostic().struct_warn_with_expectation(msg, id)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_span_allow<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -330,10 +355,14 @@ impl Session {
         self.diagnostic().struct_span_allow(sp, msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_allow(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         self.diagnostic().struct_allow(msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_expect(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -342,6 +371,8 @@ impl Session {
         self.diagnostic().struct_expect(msg, id)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_span_err<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -350,6 +381,8 @@ impl Session {
         self.diagnostic().struct_span_err(sp, msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_span_err_with_code<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -360,6 +393,8 @@ impl Session {
     }
     // FIXME: This method should be removed (every error should have an associated error code).
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_err(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -367,6 +402,8 @@ impl Session {
         self.parse_sess.struct_err(msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_err_with_code(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -375,6 +412,8 @@ impl Session {
         self.diagnostic().struct_err_with_code(msg, code)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_warn_with_code(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -383,6 +422,8 @@ impl Session {
         self.diagnostic().struct_warn_with_code(msg, code)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_span_fatal<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -391,6 +432,8 @@ impl Session {
         self.diagnostic().struct_span_fatal(sp, msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_span_fatal_with_code<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -400,15 +443,21 @@ impl Session {
         self.diagnostic().struct_span_fatal_with_code(sp, msg, code)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_fatal(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, !> {
         self.diagnostic().struct_fatal(msg)
     }
 
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, msg: impl Into<DiagnosticMessage>) -> ! {
         self.diagnostic().span_fatal(sp, msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn span_fatal_with_code<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -418,10 +467,14 @@ impl Session {
         self.diagnostic().span_fatal_with_code(sp, msg, code)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn fatal(&self, msg: impl Into<DiagnosticMessage>) -> ! {
         self.diagnostic().fatal(msg).raise()
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn span_err_or_warn<S: Into<MultiSpan>>(
         &self,
         is_warning: bool,
@@ -435,6 +488,8 @@ impl Session {
         }
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn span_err<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -443,6 +498,8 @@ impl Session {
         self.diagnostic().span_err(sp, msg)
     }
     #[rustc_lint_diagnostics]
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn span_err_with_code<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -467,6 +524,9 @@ impl Session {
         feature: Symbol,
     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         let mut err = self.parse_sess.create_err(err);
+        if err.code.is_none() {
+            err.code = std::option::Option::Some(error_code!(E0658));
+        }
         add_feature_diagnostics(&mut err, &self.parse_sess, feature);
         err
     }
@@ -482,6 +542,15 @@ impl Session {
     pub fn emit_warning<'a>(&'a self, warning: impl SessionDiagnostic<'a, ()>) {
         self.parse_sess.emit_warning(warning)
     }
+    pub fn create_fatal<'a>(
+        &'a self,
+        fatal: impl SessionDiagnostic<'a, !>,
+    ) -> DiagnosticBuilder<'a, !> {
+        self.parse_sess.create_fatal(fatal)
+    }
+    pub fn emit_fatal<'a>(&'a self, fatal: impl SessionDiagnostic<'a, !>) -> ! {
+        self.parse_sess.emit_fatal(fatal)
+    }
     #[inline]
     pub fn err_count(&self) -> usize {
         self.diagnostic().err_count()
@@ -516,9 +585,13 @@ impl Session {
             Err(ErrorGuaranteed::unchecked_claim_error_was_emitted())
         }
     }
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: impl Into<DiagnosticMessage>) {
         self.diagnostic().span_warn(sp, msg)
     }
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn span_warn_with_code<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -567,6 +640,8 @@ impl Session {
     ) {
         self.diagnostic().span_note_without_error(sp, msg)
     }
+    #[allow(rustc::untranslatable_diagnostic)]
+    #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn struct_note_without_error(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -638,7 +713,7 @@ impl Session {
         let found_positive = requested_features.clone().any(|r| r == "+crt-static");
 
         // JUSTIFICATION: necessary use of crate_types directly (see FIXME below)
-        #[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+        #[allow(rustc::bad_opt_access)]
         if found_positive || found_negative {
             found_positive
         } else if crate_type == Some(CrateType::ProcMacro)
@@ -661,8 +736,9 @@ impl Session {
             )
     }
 
+    /// Returns `true` if the target can use the current split debuginfo configuration.
     pub fn target_can_use_split_dwarf(&self) -> bool {
-        !self.target.is_like_windows && !self.target.is_like_osx
+        self.target.debuginfo_kind == DebuginfoKind::Dwarf
     }
 
     pub fn generate_proc_macro_decls_symbol(&self, stable_crate_id: StableCrateId) -> String {
@@ -894,7 +970,7 @@ impl Session {
 }
 
 // JUSTIFICATION: defn of the suggested wrapper fns
-#[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+#[allow(rustc::bad_opt_access)]
 impl Session {
     pub fn verbose(&self) -> bool {
         self.opts.unstable_opts.verbose
@@ -1174,7 +1250,7 @@ impl Session {
 }
 
 // JUSTIFICATION: part of session construction
-#[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+#[allow(rustc::bad_opt_access)]
 fn default_emitter(
     sopts: &config::Options,
     registry: rustc_errors::registry::Registry,
@@ -1260,7 +1336,7 @@ pub enum DiagnosticOutput {
 }
 
 // JUSTIFICATION: literally session construction
-#[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+#[allow(rustc::bad_opt_access)]
 pub fn build_session(
     sopts: config::Options,
     local_crate_source_file: Option<PathBuf>,
@@ -1277,10 +1353,8 @@ pub fn build_session(
     let warnings_allow = sopts
         .lint_opts
         .iter()
-        .filter(|&&(ref key, _)| *key == "warnings")
-        .map(|&(_, ref level)| *level == lint::Allow)
-        .last()
-        .unwrap_or(false);
+        .rfind(|&&(ref key, _)| *key == "warnings")
+        .map_or(false, |&(_, level)| level == lint::Allow);
     let cap_lints_allow = sopts.lint_cap.map_or(false, |cap| cap == lint::Allow);
     let can_emit_warnings = !(warnings_allow || cap_lints_allow);
 
@@ -1437,7 +1511,7 @@ pub fn build_session(
 /// If it is useful to have a Session available already for validating a commandline argument, you
 /// can do so here.
 // JUSTIFICATION: needs to access args to validate them
-#[cfg_attr(not(bootstrap), allow(rustc::bad_opt_access))]
+#[allow(rustc::bad_opt_access)]
 fn validate_commandline_args_with_session_available(sess: &Session) {
     // Since we don't know if code in an rlib will be linked to statically or
     // dynamically downstream, rustc generates `__imp_` symbols that help linkers
@@ -1450,40 +1524,28 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
         && sess.opts.cg.prefer_dynamic
         && sess.target.is_like_windows
     {
-        sess.err(
-            "Linker plugin based LTO is not supported together with \
-                  `-C prefer-dynamic` when targeting Windows-like targets",
-        );
+        sess.emit_err(LinkerPluginToWindowsNotSupported);
     }
 
     // Make sure that any given profiling data actually exists so LLVM can't
     // decide to silently skip PGO.
     if let Some(ref path) = sess.opts.cg.profile_use {
         if !path.exists() {
-            sess.err(&format!(
-                "File `{}` passed to `-C profile-use` does not exist.",
-                path.display()
-            ));
+            sess.emit_err(ProfileUseFileDoesNotExist { path });
         }
     }
 
     // Do the same for sample profile data.
     if let Some(ref path) = sess.opts.unstable_opts.profile_sample_use {
         if !path.exists() {
-            sess.err(&format!(
-                "File `{}` passed to `-C profile-sample-use` does not exist.",
-                path.display()
-            ));
+            sess.emit_err(ProfileSampleUseFileDoesNotExist { path });
         }
     }
 
     // Unwind tables cannot be disabled if the target requires them.
     if let Some(include_uwtables) = sess.opts.cg.force_unwind_tables {
         if sess.target.requires_uwtable && !include_uwtables {
-            sess.err(
-                "target requires unwind tables, they cannot be disabled with \
-                     `-C force-unwind-tables=no`.",
-            );
+            sess.emit_err(TargetRequiresUnwindTables);
         }
     }
 
@@ -1493,56 +1555,56 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
     match unsupported_sanitizers.into_iter().count() {
         0 => {}
         1 => {
-            sess.err(&format!(
-                "{} sanitizer is not supported for this target",
-                unsupported_sanitizers
-            ));
+            sess.emit_err(SanitizerNotSupported { us: unsupported_sanitizers.to_string() });
         }
         _ => {
-            sess.err(&format!(
-                "{} sanitizers are not supported for this target",
-                unsupported_sanitizers
-            ));
+            sess.emit_err(SanitizersNotSupported { us: unsupported_sanitizers.to_string() });
         }
     }
     // Cannot mix and match sanitizers.
     let mut sanitizer_iter = sess.opts.unstable_opts.sanitizer.into_iter();
     if let (Some(first), Some(second)) = (sanitizer_iter.next(), sanitizer_iter.next()) {
-        sess.err(&format!("`-Zsanitizer={first}` is incompatible with `-Zsanitizer={second}`"));
+        sess.emit_err(CannotMixAndMatchSanitizers {
+            first: first.to_string(),
+            second: second.to_string(),
+        });
     }
 
     // Cannot enable crt-static with sanitizers on Linux
     if sess.crt_static(None) && !sess.opts.unstable_opts.sanitizer.is_empty() {
-        sess.err(
-            "sanitizer is incompatible with statically linked libc, \
-                                disable it using `-C target-feature=-crt-static`",
-        );
+        sess.emit_err(CannotEnableCrtStaticLinux);
     }
 
     // LLVM CFI and VFE both require LTO.
     if sess.lto() != config::Lto::Fat {
         if sess.is_sanitizer_cfi_enabled() {
-            sess.err("`-Zsanitizer=cfi` requires `-Clto`");
+            sess.emit_err(SanitizerCfiEnabled);
         }
         if sess.opts.unstable_opts.virtual_function_elimination {
-            sess.err("`-Zvirtual-function-elimination` requires `-Clto`");
+            sess.emit_err(UnstableVirtualFunctionElimination);
         }
     }
 
     if sess.opts.unstable_opts.stack_protector != StackProtector::None {
         if !sess.target.options.supports_stack_protector {
-            sess.warn(&format!(
-                "`-Z stack-protector={}` is not supported for target {} and will be ignored",
-                sess.opts.unstable_opts.stack_protector, sess.opts.target_triple
-            ))
+            sess.emit_warning(StackProtectorNotSupportedForTarget {
+                stack_protector: sess.opts.unstable_opts.stack_protector,
+                target_triple: &sess.opts.target_triple,
+            });
         }
     }
 
     if let Some(dwarf_version) = sess.opts.unstable_opts.dwarf_version {
         if dwarf_version > 5 {
-            sess.err(&format!("requested DWARF version {} is greater than 5", dwarf_version));
+            sess.emit_err(UnsupportedDwarfVersion { dwarf_version });
         }
     }
+
+    if !sess.target.options.supported_split_debuginfo.contains(&sess.split_debuginfo())
+        && !sess.opts.unstable_opts.unstable_options
+    {
+        sess.emit_err(SplitDebugInfoUnstablePlatform { debuginfo: sess.split_debuginfo() });
+    }
 }
 
 /// Holds data on the current incremental compilation session, if there is one.
@@ -1586,14 +1648,20 @@ fn early_error_handler(output: config::ErrorOutputType) -> rustc_errors::Handler
     rustc_errors::Handler::with_emitter(true, None, emitter)
 }
 
+#[allow(rustc::untranslatable_diagnostic)]
+#[allow(rustc::diagnostic_outside_of_impl)]
 pub fn early_error_no_abort(output: config::ErrorOutputType, msg: &str) -> 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: &str) -> ! {
     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: &str) {
     early_error_handler(output).struct_warn(msg).emit()
 }