Merging upstream version 1.66.0+dfsg1.

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

8 files changed, 172 insertions, 193 deletions

diff --git a/compiler/rustc_interface/src/errors.rs b/compiler/rustc_interface/src/errors.rs
index 6a497aed4..f5135c78d 100644
--- a/compiler/rustc_interface/src/errors.rs
+++ b/compiler/rustc_interface/src/errors.rs
@@ -1,11 +1,11 @@
-use rustc_macros::SessionDiagnostic;
+use rustc_macros::Diagnostic;
 use rustc_span::{Span, Symbol};
 
 use std::io;
 use std::path::Path;
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::ferris_identifier)]
+#[derive(Diagnostic)]
+#[diag(interface_ferris_identifier)]
 pub struct FerrisIdentifier {
     #[primary_span]
     pub spans: Vec<Span>,
@@ -13,76 +13,76 @@ pub struct FerrisIdentifier {
     pub first_span: Span,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::emoji_identifier)]
+#[derive(Diagnostic)]
+#[diag(interface_emoji_identifier)]
 pub struct EmojiIdentifier {
     #[primary_span]
     pub spans: Vec<Span>,
     pub ident: Symbol,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::mixed_bin_crate)]
+#[derive(Diagnostic)]
+#[diag(interface_mixed_bin_crate)]
 pub struct MixedBinCrate;
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::mixed_proc_macro_crate)]
+#[derive(Diagnostic)]
+#[diag(interface_mixed_proc_macro_crate)]
 pub struct MixedProcMacroCrate;
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::proc_macro_doc_without_arg)]
+#[derive(Diagnostic)]
+#[diag(interface_proc_macro_doc_without_arg)]
 pub struct ProcMacroDocWithoutArg;
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::error_writing_dependencies)]
+#[derive(Diagnostic)]
+#[diag(interface_error_writing_dependencies)]
 pub struct ErrorWritingDependencies<'a> {
     pub path: &'a Path,
     pub error: io::Error,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::input_file_would_be_overwritten)]
+#[derive(Diagnostic)]
+#[diag(interface_input_file_would_be_overwritten)]
 pub struct InputFileWouldBeOverWritten<'a> {
     pub path: &'a Path,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::generated_file_conflicts_with_directory)]
+#[derive(Diagnostic)]
+#[diag(interface_generated_file_conflicts_with_directory)]
 pub struct GeneratedFileConflictsWithDirectory<'a> {
     pub input_path: &'a Path,
     pub dir_path: &'a Path,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::temps_dir_error)]
+#[derive(Diagnostic)]
+#[diag(interface_temps_dir_error)]
 pub struct TempsDirError;
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::out_dir_error)]
+#[derive(Diagnostic)]
+#[diag(interface_out_dir_error)]
 pub struct OutDirError;
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::cant_emit_mir)]
+#[derive(Diagnostic)]
+#[diag(interface_cant_emit_mir)]
 pub struct CantEmitMIR {
     pub error: io::Error,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::rustc_error_fatal)]
+#[derive(Diagnostic)]
+#[diag(interface_rustc_error_fatal)]
 pub struct RustcErrorFatal {
     #[primary_span]
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::rustc_error_unexpected_annotation)]
+#[derive(Diagnostic)]
+#[diag(interface_rustc_error_unexpected_annotation)]
 pub struct RustcErrorUnexpectedAnnotation {
     #[primary_span]
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(interface::failed_writing_file)]
+#[derive(Diagnostic)]
+#[diag(interface_failed_writing_file)]
 pub struct FailedWritingFile<'a> {
     pub path: &'a Path,
     pub error: io::Error,
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index 949bd02ad..89aaa0b95 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -17,7 +17,7 @@ use rustc_session::config::{self, CheckCfg, ErrorOutputType, Input, OutputFilena
 use rustc_session::early_error;
 use rustc_session::lint;
 use rustc_session::parse::{CrateConfig, ParseSess};
-use rustc_session::{DiagnosticOutput, Session};
+use rustc_session::Session;
 use rustc_span::source_map::{FileLoader, FileName};
 use rustc_span::symbol::sym;
 use std::path::PathBuf;
@@ -25,7 +25,10 @@ use std::result;
 
 pub type Result<T> = result::Result<T, ErrorGuaranteed>;
 
-/// Represents a compiler session.
+/// Represents a compiler session. Note that every `Compiler` contains a
+/// `Session`, but `Compiler` also contains some things that cannot be in
+/// `Session`, due to `Session` being in a crate that has many fewer
+/// dependencies than this crate.
 ///
 /// Can be used to run `rustc_interface` queries.
 /// Created by passing [`Config`] to [`run_compiler`].
@@ -247,7 +250,6 @@ pub struct Config {
     pub output_dir: Option<PathBuf>,
     pub output_file: Option<PathBuf>,
     pub file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
-    pub diagnostic_output: DiagnosticOutput,
 
     pub lint_caps: FxHashMap<lint::LintId, lint::Level>,
 
@@ -276,59 +278,6 @@ pub struct Config {
     pub registry: Registry,
 }
 
-pub fn create_compiler_and_run<R>(config: Config, f: impl FnOnce(&Compiler) -> R) -> R {
-    crate::callbacks::setup_callbacks();
-
-    let registry = &config.registry;
-    let (mut sess, codegen_backend) = util::create_session(
-        config.opts,
-        config.crate_cfg,
-        config.crate_check_cfg,
-        config.diagnostic_output,
-        config.file_loader,
-        config.input_path.clone(),
-        config.lint_caps,
-        config.make_codegen_backend,
-        registry.clone(),
-    );
-
-    if let Some(parse_sess_created) = config.parse_sess_created {
-        parse_sess_created(
-            &mut Lrc::get_mut(&mut sess)
-                .expect("create_session() should never share the returned session")
-                .parse_sess,
-        );
-    }
-
-    let temps_dir = sess.opts.unstable_opts.temps_dir.as_ref().map(|o| PathBuf::from(&o));
-
-    let compiler = Compiler {
-        sess,
-        codegen_backend,
-        input: config.input,
-        input_path: config.input_path,
-        output_dir: config.output_dir,
-        output_file: config.output_file,
-        temps_dir,
-        register_lints: config.register_lints,
-        override_queries: config.override_queries,
-    };
-
-    rustc_span::with_source_map(compiler.sess.parse_sess.clone_source_map(), move || {
-        let r = {
-            let _sess_abort_error = OnDrop(|| {
-                compiler.sess.finish_diagnostics(registry);
-            });
-
-            f(&compiler)
-        };
-
-        let prof = compiler.sess.prof.clone();
-        prof.generic_activity("drop_compiler").run(move || drop(compiler));
-        r
-    })
-}
-
 // JUSTIFICATION: before session exists, only config
 #[allow(rustc::bad_opt_access)]
 pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Send) -> R {
@@ -336,7 +285,53 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
     util::run_in_thread_pool_with_globals(
         config.opts.edition,
         config.opts.unstable_opts.threads,
-        || create_compiler_and_run(config, f),
+        || {
+            crate::callbacks::setup_callbacks();
+
+            let registry = &config.registry;
+            let (mut sess, codegen_backend) = util::create_session(
+                config.opts,
+                config.crate_cfg,
+                config.crate_check_cfg,
+                config.file_loader,
+                config.input_path.clone(),
+                config.lint_caps,
+                config.make_codegen_backend,
+                registry.clone(),
+            );
+
+            if let Some(parse_sess_created) = config.parse_sess_created {
+                parse_sess_created(&mut sess.parse_sess);
+            }
+
+            let temps_dir = sess.opts.unstable_opts.temps_dir.as_ref().map(|o| PathBuf::from(&o));
+
+            let compiler = Compiler {
+                sess: Lrc::new(sess),
+                codegen_backend: Lrc::new(codegen_backend),
+                input: config.input,
+                input_path: config.input_path,
+                output_dir: config.output_dir,
+                output_file: config.output_file,
+                temps_dir,
+                register_lints: config.register_lints,
+                override_queries: config.override_queries,
+            };
+
+            rustc_span::with_source_map(compiler.sess.parse_sess.clone_source_map(), move || {
+                let r = {
+                    let _sess_abort_error = OnDrop(|| {
+                        compiler.sess.finish_diagnostics(registry);
+                    });
+
+                    f(&compiler)
+                };
+
+                let prof = compiler.sess.prof.clone();
+                prof.generic_activity("drop_compiler").run(move || drop(compiler));
+                r
+            })
+        },
     )
 }
 
diff --git a/compiler/rustc_interface/src/lib.rs b/compiler/rustc_interface/src/lib.rs
index 41cd7b0e9..a41a749ee 100644
--- a/compiler/rustc_interface/src/lib.rs
+++ b/compiler/rustc_interface/src/lib.rs
@@ -1,5 +1,4 @@
 #![feature(box_patterns)]
-#![cfg_attr(bootstrap, feature(let_else))]
 #![feature(internal_output_capture)]
 #![feature(thread_spawn_unchecked)]
 #![feature(once_cell)]
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index c41b154c3..7f1d21bf1 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -16,7 +16,6 @@ use rustc_data_structures::sync::{Lrc, OnceCell, WorkerLocal};
 use rustc_errors::{ErrorGuaranteed, PResult};
 use rustc_expand::base::{ExtCtxt, LintStoreExpand, ResolverExpand};
 use rustc_hir::def_id::StableCrateId;
-use rustc_hir::definitions::Definitions;
 use rustc_lint::{BufferedEarlyLint, EarlyCheckNode, LintStore};
 use rustc_metadata::creader::CStore;
 use rustc_middle::arena::Arena;
@@ -30,14 +29,13 @@ use rustc_plugin_impl as plugin;
 use rustc_query_impl::{OnDiskCache, Queries as TcxQueries};
 use rustc_resolve::{Resolver, ResolverArenas};
 use rustc_session::config::{CrateType, Input, OutputFilenames, OutputType};
-use rustc_session::cstore::{CrateStoreDyn, MetadataLoader, MetadataLoaderDyn};
+use rustc_session::cstore::{MetadataLoader, MetadataLoaderDyn};
 use rustc_session::output::filename_for_input;
 use rustc_session::search_paths::PathKind;
 use rustc_session::{Limit, Session};
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::FileName;
 use rustc_trait_selection::traits;
-use rustc_typeck as typeck;
 
 use std::any::Any;
 use std::cell::RefCell;
@@ -136,10 +134,7 @@ mod boxed_resolver {
             f((&mut *resolver).as_mut().unwrap())
         }
 
-        pub fn to_resolver_outputs(
-            resolver: Rc<RefCell<BoxedResolver>>,
-        ) -> (Definitions, Box<CrateStoreDyn>, ty::ResolverOutputs, ty::ResolverAstLowering)
-        {
+        pub fn to_resolver_outputs(resolver: Rc<RefCell<BoxedResolver>>) -> ty::ResolverOutputs {
             match Rc::try_unwrap(resolver) {
                 Ok(resolver) => {
                     let mut resolver = resolver.into_inner();
@@ -736,11 +731,11 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
     rustc_mir_transform::provide(providers);
     rustc_monomorphize::provide(providers);
     rustc_privacy::provide(providers);
-    typeck::provide(providers);
+    rustc_hir_analysis::provide(providers);
+    rustc_hir_typeck::provide(providers);
     ty::provide(providers);
     traits::provide(providers);
     rustc_passes::provide(providers);
-    rustc_resolve::provide(providers);
     rustc_traits::provide(providers);
     rustc_ty_utils::provide(providers);
     rustc_metadata::provide(providers);
@@ -789,8 +784,7 @@ pub fn create_global_ctxt<'tcx>(
     // incr. comp. yet.
     dep_graph.assert_ignored();
 
-    let (definitions, cstore, resolver_outputs, resolver_for_lowering) =
-        BoxedResolver::to_resolver_outputs(resolver);
+    let resolver_outputs = BoxedResolver::to_resolver_outputs(resolver);
 
     let sess = &compiler.session();
     let query_result_on_disk_cache = rustc_incremental::load_query_result_cache(sess);
@@ -817,10 +811,7 @@ pub fn create_global_ctxt<'tcx>(
                 lint_store,
                 arena,
                 hir_arena,
-                definitions,
-                cstore,
                 resolver_outputs,
-                resolver_for_lowering,
                 krate,
                 dep_graph,
                 queries.on_disk_cache.as_ref().map(OnDiskCache::as_dyn),
@@ -880,7 +871,7 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
     });
 
     // passes are timed inside typeck
-    typeck::check_crate(tcx)?;
+    rustc_hir_analysis::check_crate(tcx)?;
 
     sess.time("misc_checking_2", || {
         parallel!(
@@ -936,7 +927,7 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
     sess.time("misc_checking_3", || {
         parallel!(
             {
-                tcx.ensure().privacy_access_levels(());
+                tcx.ensure().effective_visibilities(());
 
                 parallel!(
                     {
diff --git a/compiler/rustc_interface/src/proc_macro_decls.rs b/compiler/rustc_interface/src/proc_macro_decls.rs
index 5371c513d..4c236c693 100644
--- a/compiler/rustc_interface/src/proc_macro_decls.rs
+++ b/compiler/rustc_interface/src/proc_macro_decls.rs
@@ -1,4 +1,3 @@
-use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::TyCtxt;
@@ -10,7 +9,7 @@ fn proc_macro_decls_static(tcx: TyCtxt<'_>, (): ()) -> Option<LocalDefId> {
     for id in tcx.hir().items() {
         let attrs = finder.tcx.hir().attrs(id.hir_id());
         if finder.tcx.sess.contains_name(attrs, sym::rustc_proc_macro_decls) {
-            finder.decls = Some(id.def_id);
+            finder.decls = Some(id.owner_id.def_id);
         }
     }
 
@@ -19,7 +18,7 @@ fn proc_macro_decls_static(tcx: TyCtxt<'_>, (): ()) -> Option<LocalDefId> {
 
 struct Finder<'tcx> {
     tcx: TyCtxt<'tcx>,
-    decls: Option<hir::def_id::LocalDefId>,
+    decls: Option<LocalDefId>,
 }
 
 pub(crate) fn provide(providers: &mut Providers) {
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
index 6c725a01b..91d180e1e 100644
--- a/compiler/rustc_interface/src/queries.rs
+++ b/compiler/rustc_interface/src/queries.rs
@@ -246,6 +246,10 @@ impl<'tcx> Queries<'tcx> {
                 // Don't do code generation if there were any errors
                 self.session().compile_status()?;
 
+                // If we have any delayed bugs, for example because we created TyKind::Error earlier,
+                // it's likely that codegen will only cause more ICEs, obscuring the original problem
+                self.session().diagnostic().flush_delayed();
+
                 // Hook for UI tests.
                 Self::check_for_rustc_errors_attr(tcx);
 
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index c7615a577..eb8e65a6d 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -17,7 +17,7 @@ use rustc_session::config::{CFGuard, ExternEntry, LinkerPluginLto, LtoCli, Switc
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
 use rustc_session::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
-use rustc_session::{build_session, getopts, DiagnosticOutput, Session};
+use rustc_session::{build_session, getopts, Session};
 use rustc_span::edition::{Edition, DEFAULT_EDITION};
 use rustc_span::symbol::sym;
 use rustc_span::SourceFileHashAlgorithm;
@@ -40,16 +40,7 @@ fn build_session_options_and_crate_config(matches: getopts::Matches) -> (Options
 fn mk_session(matches: getopts::Matches) -> (Session, CfgSpecs) {
     let registry = registry::Registry::new(&[]);
     let (sessopts, cfg) = build_session_options_and_crate_config(matches);
-    let sess = build_session(
-        sessopts,
-        None,
-        None,
-        registry,
-        DiagnosticOutput::Default,
-        Default::default(),
-        None,
-        None,
-    );
+    let sess = build_session(sessopts, None, None, registry, Default::default(), None, None);
     (sess, cfg)
 }
 
@@ -540,7 +531,7 @@ fn test_codegen_options_tracking_hash() {
     }
 
     // Make sure that changing an [UNTRACKED] option leaves the hash unchanged.
-    // This list is in alphabetical order.
+    // tidy-alphabetical-start
     untracked!(ar, String::from("abc"));
     untracked!(codegen_units, Some(42));
     untracked!(default_linker_libraries, true);
@@ -556,6 +547,7 @@ fn test_codegen_options_tracking_hash() {
     untracked!(rpath, true);
     untracked!(save_temps, true);
     untracked!(strip, Strip::Debuginfo);
+    // tidy-alphabetical-end
 
     macro_rules! tracked {
         ($name: ident, $non_default_value: expr) => {
@@ -567,7 +559,7 @@ fn test_codegen_options_tracking_hash() {
     }
 
     // Make sure that changing a [TRACKED] option changes the hash.
-    // This list is in alphabetical order.
+    // tidy-alphabetical-start
     tracked!(code_model, Some(CodeModel::Large));
     tracked!(control_flow_guard, CFGuard::Checks);
     tracked!(debug_assertions, Some(true));
@@ -577,8 +569,8 @@ fn test_codegen_options_tracking_hash() {
     tracked!(force_unwind_tables, Some(true));
     tracked!(inline_threshold, Some(0xf007ba11));
     tracked!(instrument_coverage, Some(InstrumentCoverage::All));
-    tracked!(linker_plugin_lto, LinkerPluginLto::LinkerPluginAuto);
     tracked!(link_dead_code, Some(true));
+    tracked!(linker_plugin_lto, LinkerPluginLto::LinkerPluginAuto);
     tracked!(llvm_args, vec![String::from("1"), String::from("2")]);
     tracked!(lto, LtoCli::Fat);
     tracked!(metadata, vec![String::from("A"), String::from("B")]);
@@ -599,6 +591,7 @@ fn test_codegen_options_tracking_hash() {
     tracked!(symbol_mangling_version, Some(SymbolManglingVersion::V0));
     tracked!(target_cpu, Some(String::from("abc")));
     tracked!(target_feature, String::from("all the features, all of them"));
+    // tidy-alphabetical-end
 }
 
 #[test]
@@ -619,12 +612,13 @@ fn test_top_level_options_tracked_no_crate() {
     }
 
     // Make sure that changing a [TRACKED_NO_CRATE_HASH] option leaves the crate hash unchanged but changes the incremental hash.
-    // This list is in alphabetical order.
-    tracked!(remap_path_prefix, vec![("/home/bors/rust".into(), "src".into())]);
+    // tidy-alphabetical-start
     tracked!(
         real_rust_source_base_dir,
         Some("/home/bors/rust/.rustup/toolchains/nightly/lib/rustlib/src/rust".into())
     );
+    tracked!(remap_path_prefix, vec![("/home/bors/rust".into(), "src".into())]);
+    // tidy-alphabetical-end
 }
 
 #[test]
@@ -641,7 +635,7 @@ fn test_unstable_options_tracking_hash() {
     }
 
     // Make sure that changing an [UNTRACKED] option leaves the hash unchanged.
-    // This list is in alphabetical order.
+    // tidy-alphabetical-start
     untracked!(assert_incr_state, Some(String::from("loaded")));
     untracked!(deduplicate_diagnostics, false);
     untracked!(dep_tasks, true);
@@ -654,6 +648,7 @@ fn test_unstable_options_tracking_hash() {
     untracked!(dump_mir_dir, String::from("abc"));
     untracked!(dump_mir_exclude_pass_number, true);
     untracked!(dump_mir_graphviz, true);
+    untracked!(dylib_lto, true);
     untracked!(emit_stack_sizes, true);
     untracked!(future_incompat_test, true);
     untracked!(hir_stats, true);
@@ -678,12 +673,12 @@ fn test_unstable_options_tracking_hash() {
     untracked!(perf_stats, true);
     // `pre_link_arg` is omitted because it just forwards to `pre_link_args`.
     untracked!(pre_link_args, vec![String::from("abc"), String::from("def")]);
-    untracked!(profile_closures, true);
     untracked!(print_llvm_passes, true);
     untracked!(print_mono_items, Some(String::from("abc")));
     untracked!(print_type_sizes, true);
     untracked!(proc_macro_backtrace, true);
     untracked!(proc_macro_execution_strategy, ProcMacroExecutionStrategy::CrossThread);
+    untracked!(profile_closures, true);
     untracked!(query_dep_graph, true);
     untracked!(save_analysis, true);
     untracked!(self_profile, SwitchWithOptPath::Enabled(None));
@@ -692,7 +687,6 @@ fn test_unstable_options_tracking_hash() {
     untracked!(span_free_formats, true);
     untracked!(temps_dir, Some(String::from("abc")));
     untracked!(threads, 99);
-    untracked!(time, true);
     untracked!(time_llvm_passes, true);
     untracked!(time_passes, true);
     untracked!(trace_macros, true);
@@ -702,6 +696,7 @@ fn test_unstable_options_tracking_hash() {
     untracked!(unstable_options, true);
     untracked!(validate_mir, true);
     untracked!(verbose, true);
+    // tidy-alphabetical-end
 
     macro_rules! tracked {
         ($name: ident, $non_default_value: expr) => {
@@ -713,7 +708,7 @@ fn test_unstable_options_tracking_hash() {
     }
 
     // Make sure that changing a [TRACKED] option changes the hash.
-    // This list is in alphabetical order.
+    // tidy-alphabetical-start
     tracked!(allow_features, Some(vec![String::from("lang_items")]));
     tracked!(always_encode_mir, true);
     tracked!(asm_comments, true);
@@ -734,10 +729,10 @@ fn test_unstable_options_tracking_hash() {
     tracked!(debug_macros, true);
     tracked!(dep_info_omit_d_target, true);
     tracked!(drop_tracking, true);
-    tracked!(export_executable_symbols, true);
     tracked!(dual_proc_macros, true);
     tracked!(dwarf_version, Some(5));
     tracked!(emit_thin_lto, false);
+    tracked!(export_executable_symbols, true);
     tracked!(fewer_names, Some(true));
     tracked!(force_unstable_if_unmarked, true);
     tracked!(fuel, Some(("abc".to_string(), 99)));
@@ -758,11 +753,10 @@ fn test_unstable_options_tracking_hash() {
     tracked!(mir_opt_level, Some(4));
     tracked!(move_size_limit, Some(4096));
     tracked!(mutable_noalias, Some(true));
-    tracked!(new_llvm_pass_manager, Some(true));
     tracked!(no_generate_arange_section, true);
     tracked!(no_link, true);
-    tracked!(no_unique_section_names, true);
     tracked!(no_profiler_runtime, true);
+    tracked!(no_unique_section_names, true);
     tracked!(oom, OomStrategy::Panic);
     tracked!(osx_rpath_install_name, true);
     tracked!(packed_bundled_libs, true);
@@ -775,8 +769,8 @@ fn test_unstable_options_tracking_hash() {
     tracked!(print_fuel, Some("abc".to_string()));
     tracked!(profile, true);
     tracked!(profile_emit, Some(PathBuf::from("abc")));
-    tracked!(profiler_runtime, "abc".to_string());
     tracked!(profile_sample_use, Some(PathBuf::from("abc")));
+    tracked!(profiler_runtime, "abc".to_string());
     tracked!(relax_elf_relocations, Some(true));
     tracked!(relro_level, Some(RelroLevel::Full));
     tracked!(remap_cwd_prefix, Some(PathBuf::from("abc")));
@@ -805,6 +799,7 @@ fn test_unstable_options_tracking_hash() {
     tracked!(verify_llvm_ir, true);
     tracked!(virtual_function_elimination, true);
     tracked!(wasi_exec_model, Some(WasiExecModel::Reactor));
+    // tidy-alphabetical-end
 
     macro_rules! tracked_no_crate_hash {
         ($name: ident, $non_default_value: expr) => {
diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index f7e70d355..519b8a7fc 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -3,22 +3,15 @@ use libloading::Library;
 use rustc_ast as ast;
 use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-#[cfg(parallel_compiler)]
-use rustc_data_structures::jobserver;
-use rustc_data_structures::sync::Lrc;
 use rustc_errors::registry::Registry;
-#[cfg(parallel_compiler)]
-use rustc_middle::ty::tls;
 use rustc_parse::validate_attr;
-#[cfg(parallel_compiler)]
-use rustc_query_impl::{QueryContext, QueryCtxt};
 use rustc_session as session;
 use rustc_session::config::CheckCfg;
 use rustc_session::config::{self, CrateType};
 use rustc_session::config::{ErrorOutputType, Input, OutputFilenames};
 use rustc_session::lint::{self, BuiltinLintDiagnostics, LintBuffer};
 use rustc_session::parse::CrateConfig;
-use rustc_session::{early_error, filesearch, output, DiagnosticOutput, Session};
+use rustc_session::{early_error, filesearch, output, Session};
 use rustc_span::edition::Edition;
 use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::source_map::FileLoader;
@@ -26,8 +19,6 @@ use rustc_span::symbol::{sym, Symbol};
 use std::env;
 use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
 use std::mem;
-#[cfg(not(parallel_compiler))]
-use std::panic;
 use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::OnceLock;
@@ -65,7 +56,6 @@ pub fn create_session(
     sopts: config::Options,
     cfg: FxHashSet<(String, Option<String>)>,
     check_cfg: CheckCfg,
-    diagnostic_output: DiagnosticOutput,
     file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
     input_path: Option<PathBuf>,
     lint_caps: FxHashMap<lint::LintId, lint::Level>,
@@ -73,7 +63,7 @@ pub fn create_session(
         Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>,
     >,
     descriptions: Registry,
-) -> (Lrc<Session>, Lrc<Box<dyn CodegenBackend>>) {
+) -> (Session, Box<dyn CodegenBackend>) {
     let codegen_backend = if let Some(make_codegen_backend) = make_codegen_backend {
         make_codegen_backend(&sopts)
     } else {
@@ -104,7 +94,6 @@ pub fn create_session(
         input_path,
         bundle,
         descriptions,
-        diagnostic_output,
         lint_caps,
         file_loader,
         target_override,
@@ -121,7 +110,7 @@ pub fn create_session(
     sess.parse_sess.config = cfg;
     sess.parse_sess.check_config = check_cfg;
 
-    (Lrc::new(sess), Lrc::new(codegen_backend))
+    (sess, codegen_backend)
 }
 
 const STACK_SIZE: usize = 8 * 1024 * 1024;
@@ -132,79 +121,86 @@ fn get_stack_size() -> Option<usize> {
     env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
 }
 
-/// Like a `thread::Builder::spawn` followed by a `join()`, but avoids the need
-/// for `'static` bounds.
-#[cfg(not(parallel_compiler))]
-fn scoped_thread<F: FnOnce() -> R + Send, R: Send>(cfg: thread::Builder, f: F) -> R {
-    // SAFETY: join() is called immediately, so any closure captures are still
-    // alive.
-    match unsafe { cfg.spawn_unchecked(f) }.unwrap().join() {
-        Ok(v) => v,
-        Err(e) => panic::resume_unwind(e),
-    }
-}
-
 #[cfg(not(parallel_compiler))]
-pub fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
+pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
     edition: Edition,
     _threads: usize,
     f: F,
 ) -> R {
-    let mut cfg = thread::Builder::new().name("rustc".to_string());
-
+    // The "thread pool" is a single spawned thread in the non-parallel
+    // compiler. We run on a spawned thread instead of the main thread (a) to
+    // provide control over the stack size, and (b) to increase similarity with
+    // the parallel compiler, in particular to ensure there is no accidental
+    // sharing of data between the main thread and the compilation thread
+    // (which might cause problems for the parallel compiler).
+    let mut builder = thread::Builder::new().name("rustc".to_string());
     if let Some(size) = get_stack_size() {
-        cfg = cfg.stack_size(size);
+        builder = builder.stack_size(size);
     }
 
-    let main_handler = move || rustc_span::create_session_globals_then(edition, f);
-
-    scoped_thread(cfg, main_handler)
-}
-
-/// Creates a new thread and forwards information in thread locals to it.
-/// The new thread runs the deadlock handler.
-/// Must only be called when a deadlock is about to happen.
-#[cfg(parallel_compiler)]
-unsafe fn handle_deadlock() {
-    let registry = rustc_rayon_core::Registry::current();
-
-    let query_map = tls::with(|tcx| {
-        QueryCtxt::from_tcx(tcx)
-            .try_collect_active_jobs()
-            .expect("active jobs shouldn't be locked in deadlock handler")
-    });
-    thread::spawn(move || rustc_query_impl::deadlock(query_map, &registry));
+    // We build the session globals and run `f` on the spawned thread, because
+    // `SessionGlobals` does not impl `Send` in the non-parallel compiler.
+    thread::scope(|s| {
+        // `unwrap` is ok here because `spawn_scoped` only panics if the thread
+        // name contains null bytes.
+        let r = builder
+            .spawn_scoped(s, move || rustc_span::create_session_globals_then(edition, f))
+            .unwrap()
+            .join();
+
+        match r {
+            Ok(v) => v,
+            Err(e) => std::panic::resume_unwind(e),
+        }
+    })
 }
 
 #[cfg(parallel_compiler)]
-pub fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
+pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
     edition: Edition,
     threads: usize,
     f: F,
 ) -> R {
-    let mut config = rayon::ThreadPoolBuilder::new()
+    use rustc_data_structures::jobserver;
+    use rustc_middle::ty::tls;
+    use rustc_query_impl::{deadlock, QueryContext, QueryCtxt};
+
+    let mut builder = rayon::ThreadPoolBuilder::new()
         .thread_name(|_| "rustc".to_string())
         .acquire_thread_handler(jobserver::acquire_thread)
         .release_thread_handler(jobserver::release_thread)
         .num_threads(threads)
-        .deadlock_handler(|| unsafe { handle_deadlock() });
-
+        .deadlock_handler(|| {
+            // On deadlock, creates a new thread and forwards information in thread
+            // locals to it. The new thread runs the deadlock handler.
+            let query_map = tls::with(|tcx| {
+                QueryCtxt::from_tcx(tcx)
+                    .try_collect_active_jobs()
+                    .expect("active jobs shouldn't be locked in deadlock handler")
+            });
+            let registry = rustc_rayon_core::Registry::current();
+            thread::spawn(move || deadlock(query_map, &registry));
+        });
     if let Some(size) = get_stack_size() {
-        config = config.stack_size(size);
+        builder = builder.stack_size(size);
     }
 
-    let with_pool = move |pool: &rayon::ThreadPool| pool.install(f);
-
+    // We create the session globals on the main thread, then create the thread
+    // pool. Upon creation, each worker thread created gets a copy of the
+    // session globals in TLS. This is possible because `SessionGlobals` impls
+    // `Send` in the parallel compiler.
     rustc_span::create_session_globals_then(edition, || {
         rustc_span::with_session_globals(|session_globals| {
-            // The main handler runs for each Rayon worker thread and sets up
-            // the thread local rustc uses. `session_globals` is captured and set
-            // on the new threads.
-            let main_handler = move |thread: rayon::ThreadBuilder| {
-                rustc_span::set_session_globals_then(session_globals, || thread.run())
-            };
-
-            config.build_scoped(main_handler, with_pool).unwrap()
+            builder
+                .build_scoped(
+                    // Initialize each new worker thread when created.
+                    move |thread: rayon::ThreadBuilder| {
+                        rustc_span::set_session_globals_then(session_globals, || thread.run())
+                    },
+                    // Run `f` on the first thread in the thread pool.
+                    move |pool: &rayon::ThreadPool| pool.install(f),
+                )
+                .unwrap()
         })
     })
 }