diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 37ee9a5140a06..03ad75ca8b4a4 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -427,7 +427,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
     tcx.ensure_with_value().early_lint_checks(());
     tcx.ensure_with_value().debugger_visualizers(LOCAL_CRATE);
     tcx.ensure_with_value().get_lang_items(());
-    let (mut resolver, krate) = tcx.resolver_for_lowering(()).steal();
+    let (mut resolver, krate) = tcx.resolver_for_lowering().steal();
 
     let ast_index = index_crate(&resolver.node_id_to_def_id, &krate);
     let mut owners = IndexVec::from_fn_n(
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 3b6bf0005a3b1..6869c14e81a4c 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -37,7 +37,7 @@ use rustc_session::config::{nightly_options, CG_OPTIONS, Z_OPTIONS};
 use rustc_session::config::{ErrorOutputType, Input, OutFileName, OutputType};
 use rustc_session::getopts::{self, Matches};
 use rustc_session::lint::{Lint, LintId};
-use rustc_session::{config, EarlyDiagCtxt, Session};
+use rustc_session::{config, filesearch, EarlyDiagCtxt, Session};
 use rustc_span::def_id::LOCAL_CRATE;
 use rustc_span::source_map::FileLoader;
 use rustc_span::symbol::sym;
@@ -418,7 +418,7 @@ fn run_compiler(
             }
 
             // Make sure name resolution and macro expansion is run.
-            queries.global_ctxt()?.enter(|tcx| tcx.resolver_for_lowering(()));
+            queries.global_ctxt()?.enter(|tcx| tcx.resolver_for_lowering());
 
             if callbacks.after_expansion(compiler, queries) == Compilation::Stop {
                 return early_exit();
@@ -886,7 +886,11 @@ pub fn version_at_macro_invocation(
 
         let debug_flags = matches.opt_strs("Z");
         let backend_name = debug_flags.iter().find_map(|x| x.strip_prefix("codegen-backend="));
-        get_codegen_backend(early_dcx, &None, backend_name).print_version();
+        let opts = config::Options::default();
+        let sysroot = filesearch::materialize_sysroot(opts.maybe_sysroot.clone());
+        let target = config::build_target_config(early_dcx, &opts, None, &sysroot);
+
+        get_codegen_backend(early_dcx, &sysroot, backend_name, &target).print_version();
     }
 }
 
@@ -1091,7 +1095,12 @@ pub fn describe_flag_categories(early_dcx: &EarlyDiagCtxt, matches: &Matches) ->
 
     if cg_flags.iter().any(|x| *x == "passes=list") {
         let backend_name = debug_flags.iter().find_map(|x| x.strip_prefix("codegen-backend="));
-        get_codegen_backend(early_dcx, &None, backend_name).print_passes();
+
+        let opts = config::Options::default();
+        let sysroot = filesearch::materialize_sysroot(opts.maybe_sysroot.clone());
+        let target = config::build_target_config(early_dcx, &opts, None, &sysroot);
+
+        get_codegen_backend(early_dcx, &sysroot, backend_name, &target).print_passes();
         return true;
     }
 
diff --git a/compiler/rustc_driver_impl/src/pretty.rs b/compiler/rustc_driver_impl/src/pretty.rs
index 768d98ce01efe..c9bbe45b21276 100644
--- a/compiler/rustc_driver_impl/src/pretty.rs
+++ b/compiler/rustc_driver_impl/src/pretty.rs
@@ -229,7 +229,7 @@ impl<'tcx> PrintExtra<'tcx> {
     {
         match self {
             PrintExtra::AfterParsing { krate, .. } => f(krate),
-            PrintExtra::NeedsAstMap { tcx } => f(&tcx.resolver_for_lowering(()).borrow().1),
+            PrintExtra::NeedsAstMap { tcx } => f(&tcx.resolver_for_lowering().borrow().1),
         }
     }
 
@@ -281,7 +281,7 @@ pub fn print<'tcx>(sess: &Session, ppm: PpMode, ex: PrintExtra<'tcx>) {
         }
         AstTreeExpanded => {
             debug!("pretty-printing expanded AST");
-            format!("{:#?}", ex.tcx().resolver_for_lowering(()).borrow().1)
+            format!("{:#?}", ex.tcx().resolver_for_lowering().borrow().1)
         }
         Hir(s) => {
             debug!("pretty printing HIR {:?}", s);
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index 284d965979ece..1a82e6c6910ae 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -16,7 +16,7 @@ use rustc_parse::maybe_new_parser_from_source_str;
 use rustc_query_impl::QueryCtxt;
 use rustc_query_system::query::print_query_stack;
 use rustc_session::config::{self, Cfg, CheckCfg, ExpectedValues, Input, OutFileName};
-use rustc_session::filesearch::sysroot_candidates;
+use rustc_session::filesearch::{self, sysroot_candidates};
 use rustc_session::parse::ParseSess;
 use rustc_session::{lint, CompilerIO, EarlyDiagCtxt, Session};
 use rustc_span::source_map::FileLoader;
@@ -339,16 +339,53 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
 
             let early_dcx = EarlyDiagCtxt::new(config.opts.error_format);
 
-            let codegen_backend = if let Some(make_codegen_backend) = config.make_codegen_backend {
-                make_codegen_backend(&config.opts)
-            } else {
-                util::get_codegen_backend(
-                    &early_dcx,
-                    &config.opts.maybe_sysroot,
-                    config.opts.unstable_opts.codegen_backend.as_deref(),
-                )
+            let sysroot = filesearch::materialize_sysroot(config.opts.maybe_sysroot.clone());
+
+            let (codegen_backend, target_override) = match config.make_codegen_backend {
+                None => {
+                    // Build a target without override, so that it can override the backend if needed
+                    let target =
+                        config::build_target_config(&early_dcx, &config.opts, None, &sysroot);
+
+                    let backend = util::get_codegen_backend(
+                        &early_dcx,
+                        &sysroot,
+                        config.opts.unstable_opts.codegen_backend.as_deref(),
+                        &target,
+                    );
+
+                    // target_override is documented to be called before init(), so this is okay
+                    let target_override = backend.target_override(&config.opts);
+
+                    // Assert that we don't use target's override of the backend and
+                    // backend's override of the target at the same time
+                    if config.opts.unstable_opts.codegen_backend.is_none()
+                        && target.default_codegen_backend.is_some()
+                        && target_override.is_some()
+                    {
+                        rustc_middle::bug!(
+                            "Codegen backend requested target override even though the target requested the backend"
+                        );
+                    }
+
+                    (backend, target_override)
+                }
+                Some(make_codegen_backend) => {
+                    // N.B. `make_codegen_backend` takes precedence over `target.default_codegen_backend`,
+                    //      which is ignored in this case.
+                    let backend = make_codegen_backend(&config.opts);
+
+                    // target_override is documented to be called before init(), so this is okay
+                    let target_override = backend.target_override(&config.opts);
+
+                    (backend, target_override)
+                }
             };
 
+            // Re-build target with the (potential) override
+            let target_cfg =
+                config::build_target_config(&early_dcx, &config.opts, target_override, &sysroot);
+
             let temps_dir = config.opts.unstable_opts.temps_dir.as_deref().map(PathBuf::from);
 
             let bundle = match rustc_errors::fluent_bundle(
@@ -367,9 +404,6 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             let mut locale_resources = Vec::from(config.locale_resources);
             locale_resources.push(codegen_backend.locale_resource());
 
-            // target_override is documented to be called before init(), so this is okay
-            let target_override = codegen_backend.target_override(&config.opts);
-
             let mut sess = rustc_session::build_session(
                 early_dcx,
                 config.opts,
@@ -384,7 +418,8 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
                 locale_resources,
                 config.lint_caps,
                 config.file_loader,
-                target_override,
+                target_cfg,
+                sysroot,
                 util::rustc_version_str().unwrap_or("unknown"),
                 config.ice_file,
                 config.using_internal_features,
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index 085e90260515b..b571226860069 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -280,7 +280,7 @@ fn configure_and_expand(
 
 fn early_lint_checks(tcx: TyCtxt<'_>, (): ()) {
     let sess = tcx.sess;
-    let (resolver, krate) = &*tcx.resolver_for_lowering(()).borrow();
+    let (resolver, krate) = &*tcx.resolver_for_lowering().borrow();
     let mut lint_buffer = resolver.lint_buffer.steal();
 
     if sess.opts.unstable_opts.input_stats {
@@ -531,10 +531,10 @@ fn write_out_deps(tcx: TyCtxt<'_>, outputs: &OutputFilenames, out_filenames: &[P
     }
 }
 
-fn resolver_for_lowering<'tcx>(
+fn resolver_for_lowering_raw<'tcx>(
     tcx: TyCtxt<'tcx>,
     (): (),
-) -> &'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)> {
+) -> (&'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)>, &'tcx ty::ResolverGlobalCtxt) {
     let arenas = Resolver::arenas();
     let _ = tcx.registered_tools(()); // Uses `crate_for_resolver`.
     let (krate, pre_configured_attrs) = tcx.crate_for_resolver(()).steal();
@@ -549,16 +549,15 @@ fn resolver_for_lowering<'tcx>(
         ast_lowering: untracked_resolver_for_lowering,
     } = resolver.into_outputs();
 
-    let feed = tcx.feed_unit_query();
-    feed.resolutions(tcx.arena.alloc(untracked_resolutions));
-    tcx.arena.alloc(Steal::new((untracked_resolver_for_lowering, Lrc::new(krate))))
+    let resolutions = tcx.arena.alloc(untracked_resolutions);
+    (tcx.arena.alloc(Steal::new((untracked_resolver_for_lowering, Lrc::new(krate)))), resolutions)
 }
 
 pub(crate) fn write_dep_info(tcx: TyCtxt<'_>) {
     // Make sure name resolution and macro expansion is run for
     // the side-effect of providing a complete set of all
     // accessed files and env vars.
-    let _ = tcx.resolver_for_lowering(());
+    let _ = tcx.resolver_for_lowering();
 
     let sess = tcx.sess;
     let _timer = sess.timer("write_dep_info");
@@ -607,7 +606,10 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
     let providers = &mut Providers::default();
     providers.analysis = analysis;
     providers.hir_crate = rustc_ast_lowering::lower_to_hir;
-    providers.resolver_for_lowering = resolver_for_lowering;
+    providers.resolver_for_lowering_raw = resolver_for_lowering_raw;
+    providers.stripped_cfg_items =
+        |tcx, _| tcx.arena.alloc_from_iter(tcx.resolutions(()).stripped_cfg_items.steal());
+    providers.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
     providers.early_lint_checks = early_lint_checks;
     proc_macro_decls::provide(providers);
     rustc_const_eval::provide(providers);
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
index 7cdf7cd25b1c1..da11d090b7497 100644
--- a/compiler/rustc_interface/src/queries.rs
+++ b/compiler/rustc_interface/src/queries.rs
@@ -8,8 +8,7 @@ use rustc_codegen_ssa::CodegenResults;
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::{AppendOnlyIndexVec, FreezeLock, OnceLock, WorkerLocal};
-use rustc_hir::def::DefKind;
-use rustc_hir::def_id::{StableCrateId, CRATE_DEF_ID, LOCAL_CRATE};
+use rustc_hir::def_id::{StableCrateId, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
 use rustc_incremental::setup_dep_graph;
 use rustc_metadata::creader::CStore;
@@ -144,10 +143,8 @@ impl<'tcx> Queries<'tcx> {
                 stable_crate_id,
             )) as _);
             let definitions = FreezeLock::new(Definitions::new(stable_crate_id));
-            let source_span = AppendOnlyIndexVec::new();
-            let _id = source_span.push(krate.spans.inner_span);
-            debug_assert_eq!(_id, CRATE_DEF_ID);
-            let untracked = Untracked { cstore, source_span, definitions };
+            let untracked =
+                Untracked { cstore, source_span: AppendOnlyIndexVec::new(), definitions };
 
             let qcx = passes::create_global_ctxt(
                 self.compiler,
@@ -172,9 +169,6 @@ impl<'tcx> Queries<'tcx> {
                 )));
                 feed.crate_for_resolver(tcx.arena.alloc(Steal::new((krate, pre_configured_attrs))));
                 feed.output_filenames(Arc::new(outputs));
-
-                let feed = tcx.feed_local_def_id(CRATE_DEF_ID);
-                feed.def_kind(DefKind::Mod);
             });
             Ok(qcx)
         })
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 4f15d1c1d3a0b..80ca77c8f73b0 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -13,7 +13,7 @@ use rustc_session::config::{
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
 use rustc_session::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
-use rustc_session::{build_session, getopts, CompilerIO, EarlyDiagCtxt, Session};
+use rustc_session::{build_session, filesearch, getopts, CompilerIO, EarlyDiagCtxt, Session};
 use rustc_span::edition::{Edition, DEFAULT_EDITION};
 use rustc_span::symbol::sym;
 use rustc_span::{FileName, SourceFileHashAlgorithm};
@@ -37,6 +37,12 @@ fn mk_session(matches: getopts::Matches) -> (Session, Cfg) {
         output_file: None,
         temps_dir,
     };
+
+    let sysroot = filesearch::materialize_sysroot(sessopts.maybe_sysroot.clone());
+
+    let target_cfg =
+        rustc_session::config::build_target_config(&early_dcx, &sessopts, None, &sysroot);
+
     let sess = build_session(
         early_dcx,
         sessopts,
@@ -46,7 +52,8 @@ fn mk_session(matches: getopts::Matches) -> (Session, Cfg) {
         vec![],
         Default::default(),
         None,
-        None,
+        target_cfg,
+        sysroot,
         "",
         None,
         Arc::default(),
diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index 0d50200133cb2..8699187acf262 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -14,13 +14,14 @@ use rustc_session::{filesearch, output, Session};
 use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::edition::Edition;
 use rustc_span::symbol::{sym, Symbol};
+use rustc_target::spec::Target;
 use session::EarlyDiagCtxt;
-use std::env;
 use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
 use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::OnceLock;
 use std::thread;
+use std::{env, iter};
 
 /// Function pointer type that constructs a new CodegenBackend.
 pub type MakeBackendFn = fn() -> Box<dyn CodegenBackend>;
@@ -182,21 +183,25 @@ fn load_backend_from_dylib(early_dcx: &EarlyDiagCtxt, path: &Path) -> MakeBacken
 /// A name of `None` indicates that the default backend should be used.
 pub fn get_codegen_backend(
     early_dcx: &EarlyDiagCtxt,
-    maybe_sysroot: &Option<PathBuf>,
+    sysroot: &Path,
     backend_name: Option<&str>,
+    target: &Target,
 ) -> Box<dyn CodegenBackend> {
     static LOAD: OnceLock<unsafe fn() -> Box<dyn CodegenBackend>> = OnceLock::new();
 
     let load = LOAD.get_or_init(|| {
-        let default_codegen_backend = option_env!("CFG_DEFAULT_CODEGEN_BACKEND").unwrap_or("llvm");
+        let backend = backend_name
+            .or(target.default_codegen_backend.as_deref())
+            .or(option_env!("CFG_DEFAULT_CODEGEN_BACKEND"))
+            .unwrap_or("llvm");
 
-        match backend_name.unwrap_or(default_codegen_backend) {
+        match backend {
             filename if filename.contains('.') => {
                 load_backend_from_dylib(early_dcx, filename.as_ref())
             }
             #[cfg(feature = "llvm")]
             "llvm" => rustc_codegen_llvm::LlvmCodegenBackend::new,
-            backend_name => get_codegen_sysroot(early_dcx, maybe_sysroot, backend_name),
+            backend_name => get_codegen_sysroot(early_dcx, sysroot, backend_name),
         }
     });
 
@@ -231,7 +236,7 @@ fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
 #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 fn get_codegen_sysroot(
     early_dcx: &EarlyDiagCtxt,
-    maybe_sysroot: &Option<PathBuf>,
+    sysroot: &Path,
     backend_name: &str,
 ) -> MakeBackendFn {
     // For now we only allow this function to be called once as it'll dlopen a
@@ -248,28 +253,28 @@ fn get_codegen_sysroot(
     let target = session::config::host_triple();
     let sysroot_candidates = sysroot_candidates();
 
-    let sysroot = maybe_sysroot
-        .iter()
-        .chain(sysroot_candidates.iter())
+    let sysroot = iter::once(sysroot)
+        .chain(sysroot_candidates.iter().map(<_>::as_ref))
         .map(|sysroot| {
             filesearch::make_target_lib_path(sysroot, target).with_file_name("codegen-backends")
         })
         .find(|f| {
             info!("codegen backend candidate: {}", f.display());
             f.exists()
-        });
-    let sysroot = sysroot.unwrap_or_else(|| {
-        let candidates = sysroot_candidates
-            .iter()
-            .map(|p| p.display().to_string())
-            .collect::<Vec<_>>()
-            .join("\n* ");
-        let err = format!(
-            "failed to find a `codegen-backends` folder \
+        })
+        .unwrap_or_else(|| {
+            let candidates = sysroot_candidates
+                .iter()
+                .map(|p| p.display().to_string())
+                .collect::<Vec<_>>()
+                .join("\n* ");
+            let err = format!(
+                "failed to find a `codegen-backends` folder \
                            in the sysroot candidates:\n* {candidates}"
-        );
-        early_dcx.early_fatal(err);
-    });
+            );
+            early_dcx.early_fatal(err);
+        });
+
     info!("probing {} for a codegen backend", sysroot.display());
 
     let d = sysroot.read_dir().unwrap_or_else(|e| {
diff --git a/compiler/rustc_metadata/src/locator.rs b/compiler/rustc_metadata/src/locator.rs
index 90e68a6b5b916..dcccace12b00a 100644
--- a/compiler/rustc_metadata/src/locator.rs
+++ b/compiler/rustc_metadata/src/locator.rs
@@ -1077,7 +1077,7 @@ impl CrateError {
                         crate_rejections,
                     });
                 } else {
-                    dcx.emit_err(errors::CannotFindCrate {
+                    let error = errors::CannotFindCrate {
                         span,
                         crate_name,
                         add_info,
@@ -1091,11 +1091,18 @@ impl CrateError {
                         profiler_runtime: Symbol::intern(&sess.opts.unstable_opts.profiler_runtime),
                         locator_triple: locator.triple,
                         is_ui_testing: sess.opts.unstable_opts.ui_testing,
-                    });
+                    };
+                    // The diagnostic for missing core is very good, but it is followed by a lot of
+                    // other diagnostics that do not add information.
+                    if missing_core {
+                        dcx.emit_fatal(error);
+                    } else {
+                        dcx.emit_err(error);
+                    }
                 }
             }
             CrateError::NotFound(crate_name) => {
-                dcx.emit_err(errors::CannotFindCrate {
+                let error = errors::CannotFindCrate {
                     span,
                     crate_name,
                     add_info: String::new(),
@@ -1105,7 +1112,14 @@ impl CrateError {
                     profiler_runtime: Symbol::intern(&sess.opts.unstable_opts.profiler_runtime),
                     locator_triple: sess.opts.target_triple.clone(),
                     is_ui_testing: sess.opts.unstable_opts.ui_testing,
-                });
+                };
+                // The diagnostic for missing core is very good, but it is followed by a lot of
+                // other diagnostics that do not add information.
+                if missing_core {
+                    dcx.emit_fatal(error);
+                } else {
+                    dcx.emit_err(error);
+                }
             }
         }
     }
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index ebfdf8aa197fb..be8c05923207b 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -125,12 +125,11 @@ rustc_queries! {
     }
 
     query resolutions(_: ()) -> &'tcx ty::ResolverGlobalCtxt {
-        feedable
         no_hash
         desc { "getting the resolver outputs" }
     }
 
-    query resolver_for_lowering(_: ()) -> &'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)> {
+    query resolver_for_lowering_raw(_: ()) -> (&'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)>, &'tcx ty::ResolverGlobalCtxt) {
         eval_always
         no_hash
         desc { "getting the resolver for lowering" }
@@ -2221,7 +2220,6 @@ rustc_queries! {
     /// Should not be called for the local crate before the resolver outputs are created, as it
     /// is only fed there.
     query stripped_cfg_items(cnum: CrateNum) -> &'tcx [StrippedCfgItem] {
-        feedable
         desc { "getting cfg-ed out item names" }
         separate_provide_extern
     }
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 4eec93532a246..34cc5fb4096bd 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -39,7 +39,7 @@ use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::sharded::{IntoPointer, ShardedHashMap};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::steal::Steal;
-use rustc_data_structures::sync::{self, FreezeReadGuard, Lock, WorkerLocal};
+use rustc_data_structures::sync::{self, FreezeReadGuard, Lock, Lrc, WorkerLocal};
 #[cfg(parallel_compiler)]
 use rustc_data_structures::sync::{DynSend, DynSync};
 use rustc_data_structures::unord::UnordSet;
@@ -60,7 +60,7 @@ use rustc_session::config::CrateType;
 use rustc_session::cstore::{CrateStoreDyn, Untracked};
 use rustc_session::lint::Lint;
 use rustc_session::{Limit, MetadataKind, Session};
-use rustc_span::def_id::{DefPathHash, StableCrateId};
+use rustc_span::def_id::{DefPathHash, StableCrateId, CRATE_DEF_ID};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, Layout, LayoutS, TargetDataLayout, VariantIdx};
@@ -74,6 +74,7 @@ use std::cmp::Ordering;
 use std::fmt;
 use std::hash::{Hash, Hasher};
 use std::iter;
+use std::marker::PhantomData;
 use std::mem;
 use std::ops::{Bound, Deref};
 
@@ -498,14 +499,55 @@ pub struct TyCtxtFeed<'tcx, KEY: Copy> {
     key: KEY,
 }
 
+/// Never return a `Feed` from a query. Only queries that create a `DefId` are
+/// allowed to feed queries for that `DefId`.
+impl<KEY: Copy, CTX> !HashStable<CTX> for TyCtxtFeed<'_, KEY> {}
+
+/// The same as `TyCtxtFeed`, but does not contain a `TyCtxt`.
+/// Use this to pass around when you have a `TyCtxt` elsewhere.
+/// Just an optimization to save space and not store hundreds of
+/// `TyCtxtFeed` in the resolver.
+#[derive(Copy, Clone)]
+pub struct Feed<'tcx, KEY: Copy> {
+    _tcx: PhantomData<TyCtxt<'tcx>>,
+    // Do not allow direct access, as downstream code must not mutate this field.
+    key: KEY,
+}
+
+/// Never return a `Feed` from a query. Only queries that create a `DefId` are
+/// allowed to feed queries for that `DefId`.
+impl<KEY: Copy, CTX> !HashStable<CTX> for Feed<'_, KEY> {}
+
+impl<T: fmt::Debug + Copy> fmt::Debug for Feed<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.key.fmt(f)
+    }
+}
+
+/// Some workarounds to use cases that cannot use `create_def`.
+/// Do not add new ways to create `TyCtxtFeed` without consulting
+/// with T-compiler and making an analysis about why your addition
+/// does not cause incremental compilation issues.
 impl<'tcx> TyCtxt<'tcx> {
+    /// Can only be fed before queries are run, and is thus exempt from any
+    /// incremental issues. Do not use except for the initial query feeding.
     pub fn feed_unit_query(self) -> TyCtxtFeed<'tcx, ()> {
+        self.dep_graph.assert_ignored();
         TyCtxtFeed { tcx: self, key: () }
     }
+
+    /// Can only be fed before queries are run, and is thus exempt from any
+    /// incremental issues. Do not use except for the initial query feeding.
     pub fn feed_local_crate(self) -> TyCtxtFeed<'tcx, CrateNum> {
+        self.dep_graph.assert_ignored();
         TyCtxtFeed { tcx: self, key: LOCAL_CRATE }
     }
-    pub fn feed_local_def_id(self, key: LocalDefId) -> TyCtxtFeed<'tcx, LocalDefId> {
+
+    /// Only used in the resolver to register the `CRATE_DEF_ID` `DefId` and feed
+    /// some queries for it. It will panic if used twice.
+    pub fn create_local_crate_def_id(self, span: Span) -> TyCtxtFeed<'tcx, LocalDefId> {
+        let key = self.untracked().source_span.push(span);
+        assert_eq!(key, CRATE_DEF_ID);
         TyCtxtFeed { tcx: self, key }
     }
 
@@ -523,6 +565,23 @@ impl<'tcx, KEY: Copy> TyCtxtFeed<'tcx, KEY> {
     pub fn key(&self) -> KEY {
         self.key
     }
+
+    #[inline(always)]
+    pub fn downgrade(self) -> Feed<'tcx, KEY> {
+        Feed { _tcx: PhantomData, key: self.key }
+    }
+}
+
+impl<'tcx, KEY: Copy> Feed<'tcx, KEY> {
+    #[inline(always)]
+    pub fn key(&self) -> KEY {
+        self.key
+    }
+
+    #[inline(always)]
+    pub fn upgrade(self, tcx: TyCtxt<'tcx>) -> TyCtxtFeed<'tcx, KEY> {
+        TyCtxtFeed { tcx, key: self.key }
+    }
 }
 
 impl<'tcx> TyCtxtFeed<'tcx, LocalDefId> {
@@ -1067,7 +1126,7 @@ impl<'tcx> TyCtxt<'tcx> {
         // needs to be re-evaluated.
         self.dep_graph.read_index(DepNodeIndex::FOREVER_RED_NODE);
 
-        let feed = self.feed_local_def_id(def_id);
+        let feed = TyCtxtFeed { tcx: self, key: def_id };
         feed.def_kind(def_kind);
         // Unique types created for closures participate in type privacy checking.
         // They have visibilities inherited from the module they are defined in.
@@ -2304,6 +2363,10 @@ impl<'tcx> TyCtxt<'tcx> {
         self.resolutions(()).module_children.get(&def_id).map_or(&[], |v| &v[..])
     }
 
+    pub fn resolver_for_lowering(self) -> &'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)> {
+        self.resolver_for_lowering_raw(()).0
+    }
+
     /// Given an `impl_id`, return the trait it implements.
     /// Return `None` if this is an inherent impl.
     pub fn impl_trait_ref(
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index b1bfd2f1105a8..4862df440e1e1 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -345,11 +345,16 @@ impl<'tcx> SizeSkeleton<'tcx> {
             ty::Array(inner, len)
                 if len.ty() == tcx.types.usize && tcx.features().transmute_generic_consts =>
             {
+                let len_eval = len.try_eval_target_usize(tcx, param_env);
+                if len_eval == Some(0) {
+                    return Ok(SizeSkeleton::Known(Size::from_bytes(0)));
+                }
+
                 match SizeSkeleton::compute(inner, tcx, param_env)? {
                     // This may succeed because the multiplication of two types may overflow
                     // but a single size of a nested array will not.
                     SizeSkeleton::Known(s) => {
-                        if let Some(c) = len.try_eval_target_usize(tcx, param_env) {
+                        if let Some(c) = len_eval {
                             let size = s
                                 .bytes()
                                 .checked_mul(c)
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 0a38d379a5216..f9314e1da1c7b 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -32,6 +32,7 @@ pub use generic_args::*;
 pub use generics::*;
 pub use intrinsic::IntrinsicDef;
 use rustc_ast as ast;
+use rustc_ast::expand::StrippedCfgItem;
 use rustc_ast::node_id::NodeMap;
 pub use rustc_ast_ir::{try_visit, Movability, Mutability};
 use rustc_attr as attr;
@@ -85,7 +86,8 @@ pub use self::consts::{
     Const, ConstData, ConstInt, ConstKind, Expr, ScalarInt, UnevaluatedConst, ValTree,
 };
 pub use self::context::{
-    tls, CtxtInterners, DeducedParamAttrs, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt, TyCtxtFeed,
+    tls, CtxtInterners, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt,
+    TyCtxtFeed,
 };
 pub use self::instance::{Instance, InstanceDef, ShortInstance, UnusedGenericParams};
 pub use self::list::List;
@@ -189,6 +191,7 @@ pub struct ResolverGlobalCtxt {
     pub doc_link_resolutions: FxHashMap<LocalDefId, DocLinkResMap>,
     pub doc_link_traits_in_scope: FxHashMap<LocalDefId, Vec<DefId>>,
     pub all_macro_rules: FxHashMap<Symbol, Res<ast::NodeId>>,
+    pub stripped_cfg_items: Steal<Vec<StrippedCfgItem>>,
 }
 
 /// Resolutions that should only be used for lowering.
diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs
index 54854cd2da995..ea9c78ca34c08 100644
--- a/compiler/rustc_parse/src/parser/stmt.rs
+++ b/compiler/rustc_parse/src/parser/stmt.rs
@@ -787,13 +787,17 @@ impl<'a> Parser<'a> {
                             let suggest_eq = if self.token.kind == token::Dot
                                 && let _ = self.bump()
                                 && let mut snapshot = self.create_snapshot_for_diagnostic()
-                                && let Ok(_) = snapshot.parse_dot_suffix_expr(
-                                    colon_sp,
-                                    self.mk_expr_err(
+                                && let Ok(_) = snapshot
+                                    .parse_dot_suffix_expr(
                                         colon_sp,
-                                        self.dcx().delayed_bug("error during `:` -> `=` recovery"),
-                                    ),
-                                ) {
+                                        self.mk_expr_err(
+                                            colon_sp,
+                                            self.dcx()
+                                                .delayed_bug("error during `:` -> `=` recovery"),
+                                        ),
+                                    )
+                                    .map_err(Diag::cancel)
+                            {
                                 true
                             } else if let Some(op) = self.check_assoc_op()
                                 && op.node.can_continue_expr_unambiguously()
diff --git a/compiler/rustc_passes/src/debugger_visualizer.rs b/compiler/rustc_passes/src/debugger_visualizer.rs
index 4bfe6be549377..96893e585491f 100644
--- a/compiler/rustc_passes/src/debugger_visualizer.rs
+++ b/compiler/rustc_passes/src/debugger_visualizer.rs
@@ -87,7 +87,7 @@ impl<'ast> rustc_ast::visit::Visitor<'ast> for DebuggerVisualizerCollector<'_> {
 
 /// Traverses and collects the debugger visualizers for a specific crate.
 fn debugger_visualizers(tcx: TyCtxt<'_>, _: LocalCrate) -> Vec<DebuggerVisualizerFile> {
-    let resolver_and_krate = tcx.resolver_for_lowering(()).borrow();
+    let resolver_and_krate = tcx.resolver_for_lowering().borrow();
     let krate = &*resolver_and_krate.1;
 
     let mut visitor = DebuggerVisualizerCollector { sess: tcx.sess, visualizers: Vec::new() };
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index d3e3e183845ee..d1368267224a7 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -243,7 +243,7 @@ impl<'ast, 'tcx> LanguageItemCollector<'ast, 'tcx> {
 
 /// Traverses and collects all the lang items in all crates.
 fn get_lang_items(tcx: TyCtxt<'_>, (): ()) -> LanguageItems {
-    let resolver = tcx.resolver_for_lowering(()).borrow();
+    let resolver = tcx.resolver_for_lowering().borrow();
     let (resolver, krate) = &*resolver;
 
     // Initialize the collector.
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 1c4aeefcbcfd0..dd18ab7d9d23e 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -25,6 +25,7 @@ use rustc_hir::def::{self, *};
 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
 use rustc_metadata::creader::LoadedMacro;
 use rustc_middle::metadata::ModChild;
+use rustc_middle::ty::Feed;
 use rustc_middle::{bug, ty};
 use rustc_span::hygiene::{ExpnId, LocalExpnId, MacroKind};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
@@ -407,7 +408,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         // Top level use tree reuses the item's id and list stems reuse their parent
         // use tree's ids, so in both cases their visibilities are already filled.
         if nested && !list_stem {
-            self.r.feed_visibility(self.r.local_def_id(id), vis);
+            self.r.feed_visibility(self.r.feed(id), vis);
         }
 
         let mut prefix_iter = parent_prefix
@@ -632,7 +633,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         &mut self,
         fields: &[ast::FieldDef],
         ident: Ident,
-        def_id: LocalDefId,
+        feed: Feed<'tcx, LocalDefId>,
         adt_res: Res,
         adt_vis: ty::Visibility,
         adt_span: Span,
@@ -643,7 +644,8 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 
         // Define a name in the type namespace if it is not anonymous.
         self.r.define(parent, ident, TypeNS, (adt_res, adt_vis, adt_span, expansion));
-        self.r.feed_visibility(def_id, adt_vis);
+        self.r.feed_visibility(feed, adt_vis);
+        let def_id = feed.key();
 
         // Record field names for error reporting.
         self.insert_field_def_ids(def_id, fields);
@@ -653,14 +655,15 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
             match &field.ty.kind {
                 ast::TyKind::AnonStruct(id, nested_fields)
                 | ast::TyKind::AnonUnion(id, nested_fields) => {
-                    let local_def_id = self.r.local_def_id(*id);
+                    let feed = self.r.feed(*id);
+                    let local_def_id = feed.key();
                     let def_id = local_def_id.to_def_id();
                     let def_kind = self.r.tcx.def_kind(local_def_id);
                     let res = Res::Def(def_kind, def_id);
                     self.build_reduced_graph_for_struct_variant(
                         &nested_fields,
                         Ident::empty(),
-                        local_def_id,
+                        feed,
                         res,
                         // Anonymous adts inherit visibility from their parent adts.
                         adt_vis,
@@ -680,12 +683,13 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         let ident = item.ident;
         let sp = item.span;
         let vis = self.resolve_visibility(&item.vis);
-        let local_def_id = self.r.local_def_id(item.id);
+        let feed = self.r.feed(item.id);
+        let local_def_id = feed.key();
         let def_id = local_def_id.to_def_id();
         let def_kind = self.r.tcx.def_kind(def_id);
         let res = Res::Def(def_kind, def_id);
 
-        self.r.feed_visibility(local_def_id, vis);
+        self.r.feed_visibility(feed, vis);
 
         match item.kind {
             ItemKind::Use(ref use_tree) => {
@@ -762,7 +766,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                 self.build_reduced_graph_for_struct_variant(
                     vdata.fields(),
                     ident,
-                    local_def_id,
+                    feed,
                     res,
                     vis,
                     sp,
@@ -795,10 +799,11 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                         }
                         ret_fields.push(field_vis.to_def_id());
                     }
-                    let ctor_def_id = self.r.local_def_id(ctor_node_id);
+                    let feed = self.r.feed(ctor_node_id);
+                    let ctor_def_id = feed.key();
                     let ctor_res = self.res(ctor_def_id);
                     self.r.define(parent, ident, ValueNS, (ctor_res, ctor_vis, sp, expansion));
-                    self.r.feed_visibility(ctor_def_id, ctor_vis);
+                    self.r.feed_visibility(feed, ctor_vis);
                     // We need the field visibility spans also for the constructor for E0603.
                     self.insert_field_visibilities_local(ctor_def_id.to_def_id(), vdata.fields());
 
@@ -812,7 +817,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                 self.build_reduced_graph_for_struct_variant(
                     vdata.fields(),
                     ident,
-                    local_def_id,
+                    feed,
                     res,
                     vis,
                     sp,
@@ -919,7 +924,8 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 
     /// Constructs the reduced graph for one foreign item.
     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem) {
-        let local_def_id = self.r.local_def_id(item.id);
+        let feed = self.r.feed(item.id);
+        let local_def_id = feed.key();
         let def_id = local_def_id.to_def_id();
         let ns = match item.kind {
             ForeignItemKind::Fn(..) => ValueNS,
@@ -931,7 +937,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         let expansion = self.parent_scope.expansion;
         let vis = self.resolve_visibility(&item.vis);
         self.r.define(parent, item.ident, ns, (self.res(def_id), vis, item.span, expansion));
-        self.r.feed_visibility(local_def_id, vis);
+        self.r.feed_visibility(feed, vis);
     }
 
     fn build_reduced_graph_for_block(&mut self, block: &Block) {
@@ -1218,7 +1224,8 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
     fn define_macro(&mut self, item: &ast::Item) -> MacroRulesScopeRef<'a> {
         let parent_scope = self.parent_scope;
         let expansion = parent_scope.expansion;
-        let def_id = self.r.local_def_id(item.id);
+        let feed = self.r.feed(item.id);
+        let def_id = feed.key();
         let (res, ident, span, macro_rules) = match &item.kind {
             ItemKind::MacroDef(def) => (self.res(def_id), item.ident, item.span, def.macro_rules),
             ItemKind::Fn(..) => match self.proc_macro_stub(item) {
@@ -1269,7 +1276,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                 self.r.check_reserved_macro_name(ident, res);
                 self.insert_unused_macro(ident, def_id, item.id);
             }
-            self.r.feed_visibility(def_id, vis);
+            self.r.feed_visibility(feed, vis);
             let scope = self.r.arenas.alloc_macro_rules_scope(MacroRulesScope::Binding(
                 self.r.arenas.alloc_macro_rules_binding(MacroRulesBinding {
                     parent_macro_rules_scope: parent_scope.macro_rules,
@@ -1293,7 +1300,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                 self.insert_unused_macro(ident, def_id, item.id);
             }
             self.r.define(module, ident, MacroNS, (res, vis, span, expansion));
-            self.r.feed_visibility(def_id, vis);
+            self.r.feed_visibility(feed, vis);
             self.parent_scope.macro_rules
         }
     }
@@ -1385,7 +1392,8 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         }
 
         let vis = self.resolve_visibility(&item.vis);
-        let local_def_id = self.r.local_def_id(item.id);
+        let feed = self.r.feed(item.id);
+        let local_def_id = feed.key();
         let def_id = local_def_id.to_def_id();
 
         if !(ctxt == AssocCtxt::Impl
@@ -1395,7 +1403,7 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
             // Trait impl item visibility is inherited from its trait when not specified
             // explicitly. In that case we cannot determine it here in early resolve,
             // so we leave a hole in the visibility table to be filled later.
-            self.r.feed_visibility(local_def_id, vis);
+            self.r.feed_visibility(feed, vis);
         }
 
         if ctxt == AssocCtxt::Trait {
@@ -1469,7 +1477,7 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
             self.visit_invoc(sf.id);
         } else {
             let vis = self.resolve_visibility(&sf.vis);
-            self.r.feed_visibility(self.r.local_def_id(sf.id), vis);
+            self.r.feed_visibility(self.r.feed(sf.id), vis);
             visit::walk_field_def(self, sf);
         }
     }
@@ -1487,10 +1495,11 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         let ident = variant.ident;
 
         // Define a name in the type namespace.
-        let def_id = self.r.local_def_id(variant.id);
+        let feed = self.r.feed(variant.id);
+        let def_id = feed.key();
         let vis = self.resolve_visibility(&variant.vis);
         self.r.define(parent, ident, TypeNS, (self.res(def_id), vis, variant.span, expn_id));
-        self.r.feed_visibility(def_id, vis);
+        self.r.feed_visibility(feed, vis);
 
         // If the variant is marked as non_exhaustive then lower the visibility to within the crate.
         let ctor_vis =
@@ -1502,10 +1511,11 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 
         // Define a constructor name in the value namespace.
         if let Some(ctor_node_id) = variant.data.ctor_node_id() {
-            let ctor_def_id = self.r.local_def_id(ctor_node_id);
+            let feed = self.r.feed(ctor_node_id);
+            let ctor_def_id = feed.key();
             let ctor_res = self.res(ctor_def_id);
             self.r.define(parent, ident, ValueNS, (ctor_res, ctor_vis, variant.span, expn_id));
-            self.r.feed_visibility(ctor_def_id, ctor_vis);
+            self.r.feed_visibility(feed, ctor_vis);
         }
 
         // Record field names for error reporting.
diff --git a/compiler/rustc_resolve/src/def_collector.rs b/compiler/rustc_resolve/src/def_collector.rs
index 12bf462a6fdfd..bb3b902c0de64 100644
--- a/compiler/rustc_resolve/src/def_collector.rs
+++ b/compiler/rustc_resolve/src/def_collector.rs
@@ -38,14 +38,16 @@ impl<'a, 'b, 'tcx> DefCollector<'a, 'b, 'tcx> {
             "create_def(node_id={:?}, def_kind={:?}, parent_def={:?})",
             node_id, def_kind, parent_def
         );
-        self.resolver.create_def(
-            parent_def,
-            node_id,
-            name,
-            def_kind,
-            self.expansion.to_expn_id(),
-            span.with_parent(None),
-        )
+        self.resolver
+            .create_def(
+                parent_def,
+                node_id,
+                name,
+                def_kind,
+                self.expansion.to_expn_id(),
+                span.with_parent(None),
+            )
+            .def_id()
     }
 
     fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_def: LocalDefId, f: F) {
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index 83ee1d8bdcb10..377d1252d5909 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -3112,7 +3112,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 );
                 rustc_middle::ty::Visibility::Public
             };
-            this.r.feed_visibility(this.r.local_def_id(id), vis);
+            this.r.feed_visibility(this.r.feed(id), vis);
         };
 
         let Some(binding) = binding else {
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 5de147c2b2444..ccb67ea78cfdb 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -52,8 +52,8 @@ use rustc_middle::metadata::ModChild;
 use rustc_middle::middle::privacy::EffectiveVisibilities;
 use rustc_middle::query::Providers;
 use rustc_middle::span_bug;
-use rustc_middle::ty::{self, MainDefinition, RegisteredTools, TyCtxt};
-use rustc_middle::ty::{ResolverGlobalCtxt, ResolverOutputs};
+use rustc_middle::ty::{self, MainDefinition, RegisteredTools, TyCtxt, TyCtxtFeed};
+use rustc_middle::ty::{Feed, ResolverGlobalCtxt, ResolverOutputs};
 use rustc_query_system::ich::StableHashingContext;
 use rustc_session::lint::builtin::PRIVATE_MACRO_USE;
 use rustc_session::lint::LintBuffer;
@@ -1117,7 +1117,7 @@ pub struct Resolver<'a, 'tcx> {
 
     next_node_id: NodeId,
 
-    node_id_to_def_id: NodeMap<LocalDefId>,
+    node_id_to_def_id: NodeMap<Feed<'tcx, LocalDefId>>,
     def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
 
     /// Indices of unnamed struct or variant fields with unresolved attributes.
@@ -1233,11 +1233,19 @@ impl<'a, 'tcx> AsMut<Resolver<'a, 'tcx>> for Resolver<'a, 'tcx> {
 
 impl<'tcx> Resolver<'_, 'tcx> {
     fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
-        self.node_id_to_def_id.get(&node).copied()
+        self.opt_feed(node).map(|f| f.key())
     }
 
     fn local_def_id(&self, node: NodeId) -> LocalDefId {
-        self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{node:?}`"))
+        self.feed(node).key()
+    }
+
+    fn opt_feed(&self, node: NodeId) -> Option<Feed<'tcx, LocalDefId>> {
+        self.node_id_to_def_id.get(&node).copied()
+    }
+
+    fn feed(&self, node: NodeId) -> Feed<'tcx, LocalDefId> {
+        self.opt_feed(node).unwrap_or_else(|| panic!("no entry for node id: `{node:?}`"))
     }
 
     fn local_def_kind(&self, node: NodeId) -> DefKind {
@@ -1253,18 +1261,19 @@ impl<'tcx> Resolver<'_, 'tcx> {
         def_kind: DefKind,
         expn_id: ExpnId,
         span: Span,
-    ) -> LocalDefId {
+    ) -> TyCtxtFeed<'tcx, LocalDefId> {
         let data = def_kind.def_path_data(name);
         assert!(
             !self.node_id_to_def_id.contains_key(&node_id),
             "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
             node_id,
             data,
-            self.tcx.definitions_untracked().def_key(self.node_id_to_def_id[&node_id]),
+            self.tcx.definitions_untracked().def_key(self.node_id_to_def_id[&node_id].key()),
         );
 
         // FIXME: remove `def_span` body, pass in the right spans here and call `tcx.at().create_def()`
-        let def_id = self.tcx.create_def(parent, name, def_kind).def_id();
+        let feed = self.tcx.create_def(parent, name, def_kind);
+        let def_id = feed.def_id();
 
         // Create the definition.
         if expn_id != ExpnId::root() {
@@ -1281,11 +1290,11 @@ impl<'tcx> Resolver<'_, 'tcx> {
         // we don't need a mapping from `NodeId` to `LocalDefId`.
         if node_id != ast::DUMMY_NODE_ID {
             debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
-            self.node_id_to_def_id.insert(node_id, def_id);
+            self.node_id_to_def_id.insert(node_id, feed.downgrade());
         }
         assert_eq!(self.def_id_to_node_id.push(node_id), def_id);
 
-        def_id
+        feed
     }
 
     fn item_generics_num_lifetimes(&self, def_id: DefId) -> usize {
@@ -1333,7 +1342,11 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         let mut def_id_to_node_id = IndexVec::default();
         assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), CRATE_DEF_ID);
         let mut node_id_to_def_id = NodeMap::default();
-        node_id_to_def_id.insert(CRATE_NODE_ID, CRATE_DEF_ID);
+        let crate_feed = tcx.create_local_crate_def_id(crate_span);
+
+        crate_feed.def_kind(DefKind::Mod);
+        let crate_feed = crate_feed.downgrade();
+        node_id_to_def_id.insert(CRATE_NODE_ID, crate_feed);
 
         let mut invocation_parents = FxHashMap::default();
         invocation_parents.insert(LocalExpnId::ROOT, (CRATE_DEF_ID, ImplTraitContext::Existential));
@@ -1484,7 +1497,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
         let root_parent_scope = ParentScope::module(graph_root, &resolver);
         resolver.invocation_parent_scopes.insert(LocalExpnId::ROOT, root_parent_scope);
-        resolver.feed_visibility(CRATE_DEF_ID, ty::Visibility::Public);
+        resolver.feed_visibility(crate_feed, ty::Visibility::Public);
 
         resolver
     }
@@ -1532,9 +1545,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         Default::default()
     }
 
-    fn feed_visibility(&mut self, def_id: LocalDefId, vis: ty::Visibility) {
-        self.tcx.feed_local_def_id(def_id).visibility(vis.to_def_id());
-        self.visibilities_for_hashing.push((def_id, vis));
+    fn feed_visibility(&mut self, feed: Feed<'tcx, LocalDefId>, vis: ty::Visibility) {
+        let feed = feed.upgrade(self.tcx);
+        feed.visibility(vis.to_def_id());
+        self.visibilities_for_hashing.push((feed.def_id(), vis));
     }
 
     pub fn into_outputs(self) -> ResolverOutputs {
@@ -1547,12 +1561,16 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         let confused_type_with_std_module = self.confused_type_with_std_module;
         let effective_visibilities = self.effective_visibilities;
 
-        self.tcx.feed_local_crate().stripped_cfg_items(self.tcx.arena.alloc_from_iter(
-            self.stripped_cfg_items.into_iter().filter_map(|item| {
-                let parent_module = self.node_id_to_def_id.get(&item.parent_module)?.to_def_id();
-                Some(StrippedCfgItem { parent_module, name: item.name, cfg: item.cfg })
-            }),
-        ));
+        let stripped_cfg_items = Steal::new(
+            self.stripped_cfg_items
+                .into_iter()
+                .filter_map(|item| {
+                    let parent_module =
+                        self.node_id_to_def_id.get(&item.parent_module)?.key().to_def_id();
+                    Some(StrippedCfgItem { parent_module, name: item.name, cfg: item.cfg })
+                })
+                .collect(),
+        );
 
         let global_ctxt = ResolverGlobalCtxt {
             expn_that_defined,
@@ -1569,6 +1587,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             doc_link_resolutions: self.doc_link_resolutions,
             doc_link_traits_in_scope: self.doc_link_traits_in_scope,
             all_macro_rules: self.all_macro_rules,
+            stripped_cfg_items,
         };
         let ast_lowering = ty::ResolverAstLowering {
             legacy_const_generic_args: self.legacy_const_generic_args,
@@ -1578,7 +1597,11 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             lifetimes_res_map: self.lifetimes_res_map,
             extra_lifetime_params_map: self.extra_lifetime_params_map,
             next_node_id: self.next_node_id,
-            node_id_to_def_id: self.node_id_to_def_id,
+            node_id_to_def_id: self
+                .node_id_to_def_id
+                .into_items()
+                .map(|(k, f)| (k, f.key()))
+                .collect(),
             def_id_to_node_id: self.def_id_to_node_id,
             trait_map: self.trait_map,
             lifetime_elision_allowed: self.lifetime_elision_allowed,
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 61a220428b03b..471d828ad7c45 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -8,7 +8,7 @@ pub use crate::options::*;
 use crate::errors::FileWriteFail;
 use crate::search_paths::SearchPath;
 use crate::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
-use crate::{lint, HashStableContext};
+use crate::{filesearch, lint, HashStableContext};
 use crate::{EarlyDiagCtxt, Session};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::stable_hasher::{StableOrd, ToStableHashKey};
@@ -1564,7 +1564,7 @@ pub fn build_configuration(sess: &Session, mut user_cfg: Cfg) -> Cfg {
     user_cfg
 }
 
-pub(super) fn build_target_config(
+pub fn build_target_config(
     early_dcx: &EarlyDiagCtxt,
     opts: &Options,
     target_override: Option<Target>,
@@ -2863,16 +2863,8 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
 
     let logical_env = parse_logical_env(early_dcx, matches);
 
-    // 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;
-    let sysroot = match &sysroot_opt {
-        Some(s) => s,
-        None => {
-            tmp_buf = crate::filesearch::get_or_default_sysroot().expect("Failed finding sysroot");
-            &tmp_buf
-        }
-    };
+    let sysroot = filesearch::materialize_sysroot(sysroot_opt);
+
     let real_rust_source_base_dir = {
         // This is the location used by the `rust-src` `rustup` component.
         let mut candidate = sysroot.join("lib/rustlib/src/rust");
@@ -2916,7 +2908,7 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         describe_lints,
         output_types,
         search_paths,
-        maybe_sysroot: sysroot_opt,
+        maybe_sysroot: Some(sysroot),
         target_triple,
         test,
         incremental,
diff --git a/compiler/rustc_session/src/filesearch.rs b/compiler/rustc_session/src/filesearch.rs
index 2456b4b3a15c2..4f0e3354680ac 100644
--- a/compiler/rustc_session/src/filesearch.rs
+++ b/compiler/rustc_session/src/filesearch.rs
@@ -193,6 +193,12 @@ pub fn sysroot_candidates() -> SmallVec<[PathBuf; 2]> {
     return sysroot_candidates;
 }
 
+/// Returns the provided sysroot or calls [`get_or_default_sysroot`] if it's none.
+/// Panics if [`get_or_default_sysroot`]  returns an error.
+pub fn materialize_sysroot(maybe_sysroot: Option<PathBuf>) -> PathBuf {
+    maybe_sysroot.unwrap_or_else(|| get_or_default_sysroot().expect("Failed finding sysroot"))
+}
+
 /// This function checks if sysroot is found using env::args().next(), and if it
 /// is not found, finds sysroot from current rustc_driver dll.
 pub fn get_or_default_sysroot() -> Result<PathBuf, String> {
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index ae1dbd13204b0..193bc8e89a48f 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -1020,7 +1020,8 @@ pub fn build_session(
     fluent_resources: Vec<&'static str>,
     driver_lint_caps: FxHashMap<lint::LintId, lint::Level>,
     file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
-    target_override: Option<Target>,
+    target_cfg: Target,
+    sysroot: PathBuf,
     cfg_version: &'static str,
     ice_file: Option<PathBuf>,
     using_internal_features: Arc<AtomicBool>,
@@ -1037,12 +1038,6 @@ pub fn build_session(
     let cap_lints_allow = sopts.lint_cap.is_some_and(|cap| cap == lint::Allow);
     let can_emit_warnings = !(warnings_allow || cap_lints_allow);
 
-    let sysroot = match &sopts.maybe_sysroot {
-        Some(sysroot) => sysroot.clone(),
-        None => filesearch::get_or_default_sysroot().expect("Failed finding sysroot"),
-    };
-
-    let target_cfg = config::build_target_config(&early_dcx, &sopts, target_override, &sysroot);
     let host_triple = TargetTriple::from_triple(config::host_triple());
     let (host, target_warnings) = Target::search(&host_triple, &sysroot).unwrap_or_else(|e| {
         early_dcx.early_fatal(format!("Error loading host specification: {e}"))
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 3fda1e1833c12..bf6015c3a46de 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -2053,6 +2053,14 @@ pub struct TargetOptions {
     /// Default number of codegen units to use in debug mode
     pub default_codegen_units: Option<u64>,
 
+    /// Default codegen backend used for this target. Defaults to `None`.
+    ///
+    /// If `None`, then `CFG_DEFAULT_CODEGEN_BACKEND` environmental variable captured when
+    /// compiling `rustc` will be used instead (or llvm if it is not set).
+    ///
+    /// N.B. when *using* the compiler, backend can always be overriden with `-Zcodegen-backend`.
+    pub default_codegen_backend: Option<StaticCow<str>>,
+
     /// Whether to generate trap instructions in places where optimization would
     /// otherwise produce control flow that falls through into unrelated memory.
     pub trap_unreachable: bool,
@@ -2359,6 +2367,7 @@ impl Default for TargetOptions {
             stack_probes: StackProbeType::None,
             min_global_align: None,
             default_codegen_units: None,
+            default_codegen_backend: None,
             trap_unreachable: true,
             requires_lto: false,
             singlethread: false,
diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
index c35bab5ef6657..41adc2e79dc74 100644
--- a/library/alloc/src/collections/vec_deque/mod.rs
+++ b/library/alloc/src/collections/vec_deque/mod.rs
@@ -559,6 +559,30 @@ impl<T> VecDeque<T> {
     pub fn with_capacity(capacity: usize) -> VecDeque<T> {
         Self::with_capacity_in(capacity, Global)
     }
+
+    /// Creates an empty deque with space for at least `capacity` elements.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the capacity exceeds `isize::MAX` _bytes_,
+    /// or if the allocator reports allocation failure.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![feature(try_with_capacity)]
+    /// # #[allow(unused)]
+    /// # fn example() -> Result<(), std::collections::TryReserveError> {
+    /// use std::collections::VecDeque;
+    ///
+    /// let deque: VecDeque<u32> = VecDeque::try_with_capacity(10)?;
+    /// # Ok(()) }
+    /// ```
+    #[inline]
+    #[unstable(feature = "try_with_capacity", issue = "91913")]
+    pub fn try_with_capacity(capacity: usize) -> Result<VecDeque<T>, TryReserveError> {
+        Ok(VecDeque { head: 0, len: 0, buf: RawVec::try_with_capacity_in(capacity, Global)? })
+    }
 }
 
 impl<T, A: Allocator> VecDeque<T, A> {
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 28695ade5bf55..ca504b05a9689 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -163,6 +163,7 @@
 #![feature(trusted_len)]
 #![feature(trusted_random_access)]
 #![feature(try_trait_v2)]
+#![feature(try_with_capacity)]
 #![feature(tuple_trait)]
 #![feature(unchecked_math)]
 #![feature(unicode_internals)]
diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs
index dd8d6f6c7e634..ace73c0fdaa5e 100644
--- a/library/alloc/src/raw_vec.rs
+++ b/library/alloc/src/raw_vec.rs
@@ -17,10 +17,19 @@ use crate::collections::TryReserveErrorKind::*;
 #[cfg(test)]
 mod tests;
 
+// One central function responsible for reporting capacity overflows. This'll
+// ensure that the code generation related to these panics is minimal as there's
+// only one location which panics rather than a bunch throughout the module.
 #[cfg(not(no_global_oom_handling))]
+#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
+fn capacity_overflow() -> ! {
+    panic!("capacity overflow");
+}
+
 enum AllocInit {
     /// The contents of the new memory are uninitialized.
     Uninitialized,
+    #[cfg(not(no_global_oom_handling))]
     /// The new memory is guaranteed to be zeroed.
     Zeroed,
 }
@@ -93,6 +102,8 @@ impl<T> RawVec<T, Global> {
     /// zero-sized. Note that if `T` is zero-sized this means you will
     /// *not* get a `RawVec` with the requested capacity.
     ///
+    /// Non-fallible version of `try_with_capacity`
+    ///
     /// # Panics
     ///
     /// Panics if the requested capacity exceeds `isize::MAX` bytes.
@@ -104,7 +115,7 @@ impl<T> RawVec<T, Global> {
     #[must_use]
     #[inline]
     pub fn with_capacity(capacity: usize) -> Self {
-        Self::with_capacity_in(capacity, Global)
+        handle_reserve(Self::try_allocate_in(capacity, AllocInit::Uninitialized, Global))
     }
 
     /// Like `with_capacity`, but guarantees the buffer is zeroed.
@@ -142,7 +153,14 @@ impl<T, A: Allocator> RawVec<T, A> {
     #[cfg(not(no_global_oom_handling))]
     #[inline]
     pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
-        Self::allocate_in(capacity, AllocInit::Uninitialized, alloc)
+        handle_reserve(Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc))
+    }
+
+    /// Like `try_with_capacity`, but parameterized over the choice of
+    /// allocator for the returned `RawVec`.
+    #[inline]
+    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
+        Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc)
     }
 
     /// Like `with_capacity_zeroed`, but parameterized over the choice
@@ -150,7 +168,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     #[cfg(not(no_global_oom_handling))]
     #[inline]
     pub fn with_capacity_zeroed_in(capacity: usize, alloc: A) -> Self {
-        Self::allocate_in(capacity, AllocInit::Zeroed, alloc)
+        handle_reserve(Self::try_allocate_in(capacity, AllocInit::Zeroed, alloc))
     }
 
     /// Converts the entire buffer into `Box<[MaybeUninit<T>]>` with the specified `len`.
@@ -179,35 +197,41 @@ impl<T, A: Allocator> RawVec<T, A> {
         }
     }
 
-    #[cfg(not(no_global_oom_handling))]
-    fn allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Self {
+    fn try_allocate_in(
+        capacity: usize,
+        init: AllocInit,
+        alloc: A,
+    ) -> Result<Self, TryReserveError> {
         // Don't allocate here because `Drop` will not deallocate when `capacity` is 0.
+
         if T::IS_ZST || capacity == 0 {
-            Self::new_in(alloc)
+            Ok(Self::new_in(alloc))
         } else {
             // We avoid `unwrap_or_else` here because it bloats the amount of
             // LLVM IR generated.
             let layout = match Layout::array::<T>(capacity) {
                 Ok(layout) => layout,
-                Err(_) => capacity_overflow(),
+                Err(_) => return Err(CapacityOverflow.into()),
             };
-            match alloc_guard(layout.size()) {
-                Ok(_) => {}
-                Err(_) => capacity_overflow(),
+
+            if let Err(err) = alloc_guard(layout.size()) {
+                return Err(err);
             }
+
             let result = match init {
                 AllocInit::Uninitialized => alloc.allocate(layout),
+                #[cfg(not(no_global_oom_handling))]
                 AllocInit::Zeroed => alloc.allocate_zeroed(layout),
             };
             let ptr = match result {
                 Ok(ptr) => ptr,
-                Err(_) => handle_alloc_error(layout),
+                Err(_) => return Err(AllocError { layout, non_exhaustive: () }.into()),
             };
 
             // Allocators currently return a `NonNull<[u8]>` whose length
             // matches the size requested. If that ever changes, the capacity
             // here should change to `ptr.len() / mem::size_of::<T>()`.
-            Self { ptr: Unique::from(ptr.cast()), cap: unsafe { Cap(capacity) }, alloc }
+            Ok(Self { ptr: Unique::from(ptr.cast()), cap: unsafe { Cap(capacity) }, alloc })
         }
     }
 
@@ -259,7 +283,7 @@ impl<T, A: Allocator> RawVec<T, A> {
         } else {
             // We could use Layout::array here which ensures the absence of isize and usize overflows
             // and could hypothetically handle differences between stride and size, but this memory
-            // has already been allocated so we know it can't overflow and currently rust does not
+            // has already been allocated so we know it can't overflow and currently Rust does not
             // support such types. So we can do better by skipping some checks and avoid an unwrap.
             const { assert!(mem::size_of::<T>() % mem::align_of::<T>() == 0) };
             unsafe {
@@ -537,11 +561,11 @@ unsafe impl<#[may_dangle] T, A: Allocator> Drop for RawVec<T, A> {
 // Central function for reserve error handling.
 #[cfg(not(no_global_oom_handling))]
 #[inline]
-fn handle_reserve(result: Result<(), TryReserveError>) {
+fn handle_reserve<T>(result: Result<T, TryReserveError>) -> T {
     match result.map_err(|e| e.kind()) {
+        Ok(res) => res,
         Err(CapacityOverflow) => capacity_overflow(),
         Err(AllocError { layout, .. }) => handle_alloc_error(layout),
-        Ok(()) => { /* yay */ }
     }
 }
 
@@ -561,12 +585,3 @@ fn alloc_guard(alloc_size: usize) -> Result<(), TryReserveError> {
         Ok(())
     }
 }
-
-// One central function responsible for reporting capacity overflows. This'll
-// ensure that the code generation related to these panics is minimal as there's
-// only one location which panics rather than a bunch throughout the module.
-#[cfg(not(no_global_oom_handling))]
-#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
-fn capacity_overflow() -> ! {
-    panic!("capacity overflow");
-}
diff --git a/library/alloc/src/raw_vec/tests.rs b/library/alloc/src/raw_vec/tests.rs
index f8cada01c0309..4194be530612d 100644
--- a/library/alloc/src/raw_vec/tests.rs
+++ b/library/alloc/src/raw_vec/tests.rs
@@ -105,13 +105,14 @@ fn zst() {
     let v: RawVec<ZST> = RawVec::with_capacity_in(100, Global);
     zst_sanity(&v);
 
-    let v: RawVec<ZST> = RawVec::allocate_in(0, AllocInit::Uninitialized, Global);
+    let v: RawVec<ZST> = RawVec::try_allocate_in(0, AllocInit::Uninitialized, Global).unwrap();
     zst_sanity(&v);
 
-    let v: RawVec<ZST> = RawVec::allocate_in(100, AllocInit::Uninitialized, Global);
+    let v: RawVec<ZST> = RawVec::try_allocate_in(100, AllocInit::Uninitialized, Global).unwrap();
     zst_sanity(&v);
 
-    let mut v: RawVec<ZST> = RawVec::allocate_in(usize::MAX, AllocInit::Uninitialized, Global);
+    let mut v: RawVec<ZST> =
+        RawVec::try_allocate_in(usize::MAX, AllocInit::Uninitialized, Global).unwrap();
     zst_sanity(&v);
 
     // Check all these operations work as expected with zero-sized elements.
diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index 98ded7f6cdf5b..c4dcff1b1c49c 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -492,6 +492,19 @@ impl String {
         String { vec: Vec::with_capacity(capacity) }
     }
 
+    /// Creates a new empty `String` with at least the specified capacity.
+    ///
+    /// # Errors
+    ///
+    /// Returns [`Err`] if the capacity exceeds `isize::MAX` bytes,
+    /// or if the memory allocator reports failure.
+    ///
+    #[inline]
+    #[unstable(feature = "try_with_capacity", issue = "91913")]
+    pub fn try_with_capacity(capacity: usize) -> Result<String, TryReserveError> {
+        Ok(String { vec: Vec::try_with_capacity(capacity)? })
+    }
+
     // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
     // required for this method definition, is not available. Since we don't
     // require this method for testing purposes, I'll just stub it
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index c0e934b3b1fcb..f2f42e63d6b0b 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -481,6 +481,22 @@ impl<T> Vec<T> {
         Self::with_capacity_in(capacity, Global)
     }
 
+    /// Constructs a new, empty `Vec<T>` with at least the specified capacity.
+    ///
+    /// The vector will be able to hold at least `capacity` elements without
+    /// reallocating. This method is allowed to allocate for more elements than
+    /// `capacity`. If `capacity` is 0, the vector will not allocate.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the capacity exceeds `isize::MAX` _bytes_,
+    /// or if the allocator reports allocation failure.
+    #[inline]
+    #[unstable(feature = "try_with_capacity", issue = "91913")]
+    pub fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
+        Self::try_with_capacity_in(capacity, Global)
+    }
+
     /// Creates a `Vec<T>` directly from a pointer, a length, and a capacity.
     ///
     /// # Safety
@@ -672,6 +688,24 @@ impl<T, A: Allocator> Vec<T, A> {
         Vec { buf: RawVec::with_capacity_in(capacity, alloc), len: 0 }
     }
 
+    /// Constructs a new, empty `Vec<T, A>` with at least the specified capacity
+    /// with the provided allocator.
+    ///
+    /// The vector will be able to hold at least `capacity` elements without
+    /// reallocating. This method is allowed to allocate for more elements than
+    /// `capacity`. If `capacity` is 0, the vector will not allocate.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the capacity exceeds `isize::MAX` _bytes_,
+    /// or if the allocator reports allocation failure.
+    #[inline]
+    #[unstable(feature = "allocator_api", issue = "32838")]
+    // #[unstable(feature = "try_with_capacity", issue = "91913")]
+    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
+        Ok(Vec { buf: RawVec::try_with_capacity_in(capacity, alloc)?, len: 0 })
+    }
+
     /// Creates a `Vec<T, A>` directly from a pointer, a length, a capacity,
     /// and an allocator.
     ///
diff --git a/library/alloc/tests/lib.rs b/library/alloc/tests/lib.rs
index ed928994ad697..e8496989bcf12 100644
--- a/library/alloc/tests/lib.rs
+++ b/library/alloc/tests/lib.rs
@@ -20,6 +20,7 @@
 #![feature(pattern)]
 #![feature(trusted_len)]
 #![feature(try_reserve_kind)]
+#![feature(try_with_capacity)]
 #![feature(unboxed_closures)]
 #![feature(associated_type_bounds)]
 #![feature(binary_heap_into_iter_sorted)]
diff --git a/library/alloc/tests/string.rs b/library/alloc/tests/string.rs
index 711e4eef2e724..e20ceae87b0d5 100644
--- a/library/alloc/tests/string.rs
+++ b/library/alloc/tests/string.rs
@@ -723,6 +723,17 @@ fn test_reserve_exact() {
     assert!(s.capacity() >= 33)
 }
 
+#[test]
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
+#[cfg_attr(target_os = "android", ignore)] // Android used in CI has a broken dlmalloc
+fn test_try_with_capacity() {
+    let string = String::try_with_capacity(1000).unwrap();
+    assert_eq!(0, string.len());
+    assert!(string.capacity() >= 1000 && string.capacity() <= isize::MAX as usize);
+
+    assert!(String::try_with_capacity(usize::MAX).is_err());
+}
+
 #[test]
 #[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 #[cfg_attr(target_os = "android", ignore)] // Android used in CI has a broken dlmalloc
diff --git a/library/alloc/tests/vec.rs b/library/alloc/tests/vec.rs
index 15ee4d6520523..aa95b4e977081 100644
--- a/library/alloc/tests/vec.rs
+++ b/library/alloc/tests/vec.rs
@@ -1694,6 +1694,18 @@ fn test_reserve_exact() {
     assert!(v.capacity() >= 33)
 }
 
+#[test]
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
+#[cfg_attr(target_os = "android", ignore)] // Android used in CI has a broken dlmalloc
+fn test_try_with_capacity() {
+    let mut vec: Vec<u32> = Vec::try_with_capacity(5).unwrap();
+    assert_eq!(0, vec.len());
+    assert!(vec.capacity() >= 5 && vec.capacity() <= isize::MAX as usize / 4);
+    assert!(vec.spare_capacity_mut().len() >= 5);
+
+    assert!(Vec::<u16>::try_with_capacity(isize::MAX as usize + 1).is_err());
+}
+
 #[test]
 #[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 #[cfg_attr(target_os = "android", ignore)] // Android used in CI has a broken dlmalloc
diff --git a/library/alloc/tests/vec_deque.rs b/library/alloc/tests/vec_deque.rs
index eda2f8bb812b5..cea5de4dd5984 100644
--- a/library/alloc/tests/vec_deque.rs
+++ b/library/alloc/tests/vec_deque.rs
@@ -1182,6 +1182,17 @@ fn test_reserve_exact_2() {
     assert!(v.capacity() >= 33)
 }
 
+#[test]
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
+#[cfg_attr(target_os = "android", ignore)] // Android used in CI has a broken dlmalloc
+fn test_try_with_capacity() {
+    let vec: VecDeque<u32> = VecDeque::try_with_capacity(5).unwrap();
+    assert_eq!(0, vec.len());
+    assert!(vec.capacity() >= 5 && vec.capacity() <= isize::MAX as usize / 4);
+
+    assert!(VecDeque::<u16>::try_with_capacity(isize::MAX as usize + 1).is_err());
+}
+
 #[test]
 #[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 #[cfg_attr(target_os = "android", ignore)] // Android used in CI has a broken dlmalloc
diff --git a/library/core/src/arch.rs b/library/core/src/arch.rs
index 8817ec0777b64..31d6bc36fc8b9 100644
--- a/library/core/src/arch.rs
+++ b/library/core/src/arch.rs
@@ -6,10 +6,10 @@ pub use crate::core_arch::arch::*;
 
 /// Inline assembly.
 ///
-/// Refer to [rust by example] for a usage guide and the [reference] for
+/// Refer to [Rust By Example] for a usage guide and the [reference] for
 /// detailed information about the syntax and available options.
 ///
-/// [rust by example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html
+/// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html
 /// [reference]: https://doc.rust-lang.org/nightly/reference/inline-assembly.html
 #[stable(feature = "asm", since = "1.59.0")]
 #[rustc_builtin_macro]
@@ -19,10 +19,10 @@ pub macro asm("assembly template", $(operands,)* $(options($(option),*))?) {
 
 /// Module-level inline assembly.
 ///
-/// Refer to [rust by example] for a usage guide and the [reference] for
+/// Refer to [Rust By Example] for a usage guide and the [reference] for
 /// detailed information about the syntax and available options.
 ///
-/// [rust by example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html
+/// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html
 /// [reference]: https://doc.rust-lang.org/nightly/reference/inline-assembly.html
 #[stable(feature = "global_asm", since = "1.59.0")]
 #[rustc_builtin_macro]
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index 643968c35e849..0ee7e190e3d45 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -1481,7 +1481,7 @@ pub(crate) mod builtin {
     /// script](https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script).
     ///
     /// When using the `include` macro to include stretches of documentation, remember that the
-    /// included file still needs to be a valid rust syntax. It is also possible to
+    /// included file still needs to be a valid Rust syntax. It is also possible to
     /// use the [`include_str`] macro as `#![doc = include_str!("...")]` (at the module level) or
     /// `#[doc = include_str!("...")]` (at the item level) to include documentation from a plain
     /// text or markdown file.
diff --git a/library/core/src/mem/maybe_uninit.rs b/library/core/src/mem/maybe_uninit.rs
index c19b5791562ce..026e21586d403 100644
--- a/library/core/src/mem/maybe_uninit.rs
+++ b/library/core/src/mem/maybe_uninit.rs
@@ -1125,22 +1125,6 @@ impl<T> MaybeUninit<T> {
         // unlike copy_from_slice this does not call clone_from_slice on the slice
         // this is because `MaybeUninit<T: Clone>` does not implement Clone.
 
-        struct Guard<'a, T> {
-            slice: &'a mut [MaybeUninit<T>],
-            initialized: usize,
-        }
-
-        impl<'a, T> Drop for Guard<'a, T> {
-            fn drop(&mut self) {
-                let initialized_part = &mut self.slice[..self.initialized];
-                // SAFETY: this raw slice will contain only initialized objects
-                // that's why, it is allowed to drop it.
-                unsafe {
-                    crate::ptr::drop_in_place(MaybeUninit::slice_assume_init_mut(initialized_part));
-                }
-            }
-        }
-
         assert_eq!(this.len(), src.len(), "destination and source slices have different lengths");
         // NOTE: We need to explicitly slice them to the same length
         // for bounds checking to be elided, and the optimizer will
@@ -1162,6 +1146,151 @@ impl<T> MaybeUninit<T> {
         unsafe { MaybeUninit::slice_assume_init_mut(this) }
     }
 
+    /// Fills `this` with elements by cloning `value`, returning a mutable reference to the now
+    /// initialized contents of `this`.
+    /// Any previously initialized elements will not be dropped.
+    ///
+    /// This is similar to [`slice::fill`].
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if any call to `Clone` panics.
+    ///
+    /// If such a panic occurs, any elements previously initialized during this operation will be
+    /// dropped.
+    ///
+    /// # Examples
+    ///
+    /// Fill an uninit vec with 1.
+    /// ```
+    /// #![feature(maybe_uninit_fill)]
+    /// use std::mem::MaybeUninit;
+    ///
+    /// let mut buf = vec![MaybeUninit::uninit(); 10];
+    /// let initialized = MaybeUninit::fill(buf.as_mut_slice(), 1);
+    /// assert_eq!(initialized, &mut [1; 10]);
+    /// ```
+    #[doc(alias = "memset")]
+    #[unstable(feature = "maybe_uninit_fill", issue = "117428")]
+    pub fn fill<'a>(this: &'a mut [MaybeUninit<T>], value: T) -> &'a mut [T]
+    where
+        T: Clone,
+    {
+        SpecFill::spec_fill(this, value);
+        // SAFETY: Valid elements have just been filled into `this` so it is initialized
+        unsafe { MaybeUninit::slice_assume_init_mut(this) }
+    }
+
+    /// Fills `this` with elements returned by calling a closure repeatedly.
+    ///
+    /// This method uses a closure to create new values.  If you'd rather `Clone` a given value, use
+    /// [`MaybeUninit::fill`].  If you want to use the `Default` trait to generate values, you can
+    /// pass [`Default::default`] as the argument.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if any call to the provided closure panics.
+    ///
+    /// If such a panic occurs, any elements previously initialized during this operation will be
+    /// dropped.
+    ///
+    /// # Examples
+    ///
+    /// Fill an uninit vec with the default value.
+    /// ```
+    /// #![feature(maybe_uninit_fill)]
+    /// use std::mem::MaybeUninit;
+    ///
+    /// let mut buf = vec![MaybeUninit::<i32>::uninit(); 10];
+    /// let initialized = MaybeUninit::fill_with(buf.as_mut_slice(), Default::default);
+    /// assert_eq!(initialized, &mut [0; 10]);
+    /// ```
+    #[unstable(feature = "maybe_uninit_fill", issue = "117428")]
+    pub fn fill_with<'a, F>(this: &'a mut [MaybeUninit<T>], mut f: F) -> &'a mut [T]
+    where
+        F: FnMut() -> T,
+    {
+        let mut guard = Guard { slice: this, initialized: 0 };
+
+        for element in guard.slice.iter_mut() {
+            element.write(f());
+            guard.initialized += 1;
+        }
+
+        super::forget(guard);
+
+        // SAFETY: Valid elements have just been written into `this` so it is initialized
+        unsafe { MaybeUninit::slice_assume_init_mut(this) }
+    }
+
+    /// Fills `this` with elements yielded by an iterator until either all elements have been
+    /// initialized or the iterator is empty.
+    ///
+    /// Returns two slices.  The first slice contains the initialized portion of the original slice.
+    /// The second slice is the still-uninitialized remainder of the original slice.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if the iterator's `next` function panics.
+    ///
+    /// If such a panic occurs, any elements previously initialized during this operation will be
+    /// dropped.
+    ///
+    /// # Examples
+    ///
+    /// Fill an uninit vec with a cycling iterator.
+    /// ```
+    /// #![feature(maybe_uninit_fill)]
+    /// use std::mem::MaybeUninit;
+    ///
+    /// let mut buf = vec![MaybeUninit::uninit(); 5];
+    ///
+    /// let iter = [1, 2, 3].into_iter().cycle();
+    /// let (initialized, remainder) = MaybeUninit::fill_from(&mut buf, iter);
+    ///
+    /// assert_eq!(initialized, &mut [1, 2, 3, 1, 2]);
+    /// assert_eq!(0, remainder.len());
+    /// ```
+    ///
+    /// Fill an uninit vec, but not completely.
+    /// ```
+    /// #![feature(maybe_uninit_fill)]
+    /// use std::mem::MaybeUninit;
+    ///
+    /// let mut buf = vec![MaybeUninit::uninit(); 5];
+    /// let iter = [1, 2];
+    /// let (initialized, remainder) = MaybeUninit::fill_from(&mut buf, iter);
+    ///
+    /// assert_eq!(initialized, &mut [1, 2]);
+    /// assert_eq!(remainder.len(), 3);
+    /// ```
+    #[unstable(feature = "maybe_uninit_fill", issue = "117428")]
+    pub fn fill_from<'a, I>(
+        this: &'a mut [MaybeUninit<T>],
+        it: I,
+    ) -> (&'a mut [T], &'a mut [MaybeUninit<T>])
+    where
+        I: IntoIterator<Item = T>,
+    {
+        let iter = it.into_iter();
+        let mut guard = Guard { slice: this, initialized: 0 };
+
+        for (element, val) in guard.slice.iter_mut().zip(iter) {
+            element.write(val);
+            guard.initialized += 1;
+        }
+
+        let initialized_len = guard.initialized;
+        super::forget(guard);
+
+        // SAFETY: guard.initialized <= this.len()
+        let (initted, remainder) = unsafe { this.split_at_mut_unchecked(initialized_len) };
+
+        // SAFETY: Valid elements have just been written into `init`, so that portion
+        // of `this` is initialized.
+        (unsafe { MaybeUninit::slice_assume_init_mut(initted) }, remainder)
+    }
+
     /// Returns the contents of this `MaybeUninit` as a slice of potentially uninitialized bytes.
     ///
     /// Note that even if the contents of a `MaybeUninit` have been initialized, the value may still
@@ -1315,3 +1444,44 @@ impl<T, const N: usize> [MaybeUninit<T>; N] {
         unsafe { intrinsics::transmute_unchecked(self) }
     }
 }
+
+struct Guard<'a, T> {
+    slice: &'a mut [MaybeUninit<T>],
+    initialized: usize,
+}
+
+impl<'a, T> Drop for Guard<'a, T> {
+    fn drop(&mut self) {
+        let initialized_part = &mut self.slice[..self.initialized];
+        // SAFETY: this raw sub-slice will contain only initialized objects.
+        unsafe {
+            crate::ptr::drop_in_place(MaybeUninit::slice_assume_init_mut(initialized_part));
+        }
+    }
+}
+
+trait SpecFill<T> {
+    fn spec_fill(&mut self, value: T);
+}
+
+impl<T: Clone> SpecFill<T> for [MaybeUninit<T>] {
+    default fn spec_fill(&mut self, value: T) {
+        let mut guard = Guard { slice: self, initialized: 0 };
+
+        if let Some((last, elems)) = guard.slice.split_last_mut() {
+            for el in elems {
+                el.write(value.clone());
+                guard.initialized += 1;
+            }
+
+            last.write(value);
+        }
+        super::forget(guard);
+    }
+}
+
+impl<T: Copy> SpecFill<T> for [MaybeUninit<T>] {
+    fn spec_fill(&mut self, value: T) {
+        self.fill(MaybeUninit::new(value));
+    }
+}
diff --git a/library/core/src/ptr/alignment.rs b/library/core/src/ptr/alignment.rs
index 3eea065eef64e..3508b0c7f238d 100644
--- a/library/core/src/ptr/alignment.rs
+++ b/library/core/src/ptr/alignment.rs
@@ -3,7 +3,7 @@ use crate::num::NonZero;
 use crate::{cmp, fmt, hash, mem, num};
 
 /// A type storing a `usize` which is a power of two, and thus
-/// represents a possible alignment in the rust abstract machine.
+/// represents a possible alignment in the Rust abstract machine.
 ///
 /// Note that particularly large alignments, while representable in this type,
 /// are likely not to be supported by actual allocators and linkers.
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index aaedbed0d550c..643b7971a662d 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -23,7 +23,7 @@ use crate::slice;
     issue = "none",
     reason = "exposed from core to be reused in std; use the memchr crate"
 )]
-/// Pure rust memchr implementation, taken from rust-memchr
+/// Pure Rust memchr implementation, taken from rust-memchr
 pub mod memchr;
 
 #[unstable(
diff --git a/library/core/src/sync/exclusive.rs b/library/core/src/sync/exclusive.rs
index fa02dd52e0027..e8170c13ed263 100644
--- a/library/core/src/sync/exclusive.rs
+++ b/library/core/src/sync/exclusive.rs
@@ -19,7 +19,7 @@ use core::task::{Context, Poll};
 ///
 /// Certain constructs like [`Future`]s can only be used with _exclusive_ access,
 /// and are often `Send` but not `Sync`, so `Exclusive` can be used as hint to the
-/// rust compiler that something is `Sync` in practice.
+/// Rust compiler that something is `Sync` in practice.
 ///
 /// ## Examples
 /// Using a non-`Sync` future prevents the wrapping struct from being `Sync`
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index fa0e9a979d060..c5a7e87c4aa4f 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -54,6 +54,7 @@
 #![feature(slice_from_ptr_range)]
 #![feature(slice_split_once)]
 #![feature(split_as_slice)]
+#![feature(maybe_uninit_fill)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(maybe_uninit_write_slice)]
 #![feature(maybe_uninit_uninit_array_transpose)]
diff --git a/library/core/tests/mem.rs b/library/core/tests/mem.rs
index 0f7fde747690a..e388800f400df 100644
--- a/library/core/tests/mem.rs
+++ b/library/core/tests/mem.rs
@@ -308,21 +308,226 @@ fn uninit_write_slice_cloned_mid_panic() {
     }
 }
 
+#[derive(Clone)]
+struct Bomb;
+
+impl Drop for Bomb {
+    fn drop(&mut self) {
+        panic!("dropped a bomb! kaboom!")
+    }
+}
+
 #[test]
 fn uninit_write_slice_cloned_no_drop() {
-    #[derive(Clone)]
-    struct Bomb;
+    let mut dst = [MaybeUninit::uninit()];
+    let src = [Bomb];
+
+    MaybeUninit::clone_from_slice(&mut dst, &src);
+
+    forget(src);
+}
+
+#[test]
+fn uninit_fill() {
+    let mut dst = [MaybeUninit::new(255); 64];
+    let expect = [0; 64];
+
+    assert_eq!(MaybeUninit::fill(&mut dst, 0), &expect);
+}
+
+#[cfg(panic = "unwind")]
+struct CloneUntilPanic {
+    limit: usize,
+    rc: Rc<()>,
+}
 
-    impl Drop for Bomb {
-        fn drop(&mut self) {
-            panic!("dropped a bomb! kaboom")
+#[cfg(panic = "unwind")]
+impl Clone for CloneUntilPanic {
+    fn clone(&self) -> Self {
+        if Rc::strong_count(&self.rc) >= self.limit {
+            panic!("expected panic on clone");
         }
+        Self { limit: self.limit, rc: self.rc.clone() }
     }
+}
+
+#[test]
+#[cfg(panic = "unwind")]
+fn uninit_fill_clone_panic_drop() {
+    use std::panic;
+
+    let rc = Rc::new(());
+
+    let mut dst = [MaybeUninit::uninit(), MaybeUninit::uninit(), MaybeUninit::uninit()];
+
+    let src = CloneUntilPanic { limit: 3, rc: rc.clone() };
+    let err = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        MaybeUninit::fill(&mut dst, src);
+    }));
+
+    match err {
+        Ok(_) => unreachable!(),
+        Err(payload) => {
+            payload
+                .downcast::<&'static str>()
+                .and_then(|s| if *s == "expected panic on clone" { Ok(s) } else { Err(s) })
+                .unwrap_or_else(|p| panic::resume_unwind(p));
+            assert_eq!(Rc::strong_count(&rc), 1)
+        }
+    }
+}
+
+#[test]
+#[cfg(panic = "unwind")]
+fn uninit_fill_clone_no_drop_clones() {
+    let mut dst = [MaybeUninit::uninit(), MaybeUninit::uninit(), MaybeUninit::uninit()];
+
+    MaybeUninit::fill(&mut dst, Bomb);
+}
+
+#[test]
+fn uninit_fill_with() {
+    let mut dst = [MaybeUninit::new(255); 64];
+    let expect = [0; 64];
+
+    assert_eq!(MaybeUninit::fill_with(&mut dst, || 0), &expect);
+}
+
+#[test]
+#[cfg(panic = "unwind")]
+fn uninit_fill_with_mid_panic() {
+    use std::panic;
+
+    let rc = Rc::new(());
+
+    let mut dst = [MaybeUninit::uninit(), MaybeUninit::uninit(), MaybeUninit::uninit()];
+
+    let src = CloneUntilPanic { limit: 3, rc: rc.clone() };
+    let err = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        MaybeUninit::fill_with(&mut dst, || src.clone());
+    }));
+
+    drop(src);
+
+    match err {
+        Ok(_) => unreachable!(),
+        Err(payload) => {
+            payload
+                .downcast::<&'static str>()
+                .and_then(|s| if *s == "expected panic on clone" { Ok(s) } else { Err(s) })
+                .unwrap_or_else(|p| panic::resume_unwind(p));
 
+            assert_eq!(Rc::strong_count(&rc), 1)
+        }
+    }
+}
+
+#[test]
+#[cfg(panic = "unwind")]
+fn uninit_fill_with_no_drop() {
+    let mut dst = [MaybeUninit::uninit()];
+    let src = Bomb;
+
+    MaybeUninit::fill_with(&mut dst, || src.clone());
+
+    forget(src);
+}
+
+#[test]
+fn uninit_fill_from() {
+    let mut dst = [MaybeUninit::new(255); 64];
+    let src = [0; 64];
+
+    let (initted, remainder) = MaybeUninit::fill_from(&mut dst, src.into_iter());
+    assert_eq!(initted, &src);
+    assert_eq!(remainder.len(), 0);
+}
+
+#[test]
+fn uninit_fill_from_partial() {
+    let mut dst = [MaybeUninit::new(255); 64];
+    let src = [0; 48];
+
+    let (initted, remainder) = MaybeUninit::fill_from(&mut dst, src.into_iter());
+    assert_eq!(initted, &src);
+    assert_eq!(remainder.len(), 16);
+}
+
+#[test]
+fn uninit_over_fill() {
+    let mut dst = [MaybeUninit::new(255); 64];
+    let src = [0; 72];
+
+    let (initted, remainder) = MaybeUninit::fill_from(&mut dst, src.into_iter());
+    assert_eq!(initted, &src[0..64]);
+    assert_eq!(remainder.len(), 0);
+}
+
+#[test]
+fn uninit_empty_fill() {
+    let mut dst = [MaybeUninit::new(255); 64];
+    let src = [0; 0];
+
+    let (initted, remainder) = MaybeUninit::fill_from(&mut dst, src.into_iter());
+    assert_eq!(initted, &src[0..0]);
+    assert_eq!(remainder.len(), 64);
+}
+
+#[test]
+#[cfg(panic = "unwind")]
+fn uninit_fill_from_mid_panic() {
+    use std::panic;
+
+    struct IterUntilPanic {
+        limit: usize,
+        rc: Rc<()>,
+    }
+
+    impl Iterator for IterUntilPanic {
+        type Item = Rc<()>;
+        fn next(&mut self) -> Option<Self::Item> {
+            if Rc::strong_count(&self.rc) >= self.limit {
+                panic!("expected panic on next");
+            }
+            Some(self.rc.clone())
+        }
+    }
+
+    let rc = Rc::new(());
+
+    let mut dst = [
+        MaybeUninit::uninit(),
+        MaybeUninit::uninit(),
+        MaybeUninit::uninit(),
+        MaybeUninit::uninit(),
+    ];
+
+    let src = IterUntilPanic { limit: 3, rc: rc.clone() };
+
+    let err = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        MaybeUninit::fill_from(&mut dst, src);
+    }));
+
+    match err {
+        Ok(_) => unreachable!(),
+        Err(payload) => {
+            payload
+                .downcast::<&'static str>()
+                .and_then(|s| if *s == "expected panic on next" { Ok(s) } else { Err(s) })
+                .unwrap_or_else(|p| panic::resume_unwind(p));
+
+            assert_eq!(Rc::strong_count(&rc), 1)
+        }
+    }
+}
+
+#[test]
+#[cfg(panic = "unwind")]
+fn uninit_fill_from_no_drop() {
     let mut dst = [MaybeUninit::uninit()];
     let src = [Bomb];
 
-    MaybeUninit::clone_from_slice(&mut dst, &src);
+    MaybeUninit::fill_from(&mut dst, src.iter());
 
     forget(src);
 }
diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index e44da8e637e98..8927e9a47fa83 100644
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -157,7 +157,7 @@ impl OsString {
     /// # Safety
     ///
     /// As the encoding is unspecified, callers must pass in bytes that originated as a mixture of
-    /// validated UTF-8 and bytes from [`OsStr::as_encoded_bytes`] from within the same rust version
+    /// validated UTF-8 and bytes from [`OsStr::as_encoded_bytes`] from within the same Rust version
     /// built for the same target platform.  For example, reconstructing an `OsString` from bytes sent
     /// over the network or stored in a file will likely violate these safety rules.
     ///
@@ -213,7 +213,7 @@ impl OsString {
     /// ASCII.
     ///
     /// Note: As the encoding is unspecified, any sub-slice of bytes that is not valid UTF-8 should
-    /// be treated as opaque and only comparable within the same rust version built for the same
+    /// be treated as opaque and only comparable within the same Rust version built for the same
     /// target platform.  For example, sending the bytes over the network or storing it in a file
     /// will likely result in incompatible data.  See [`OsString`] for more encoding details
     /// and [`std::ffi`] for platform-specific, specified conversions.
@@ -747,7 +747,7 @@ impl OsStr {
     /// # Safety
     ///
     /// As the encoding is unspecified, callers must pass in bytes that originated as a mixture of
-    /// validated UTF-8 and bytes from [`OsStr::as_encoded_bytes`] from within the same rust version
+    /// validated UTF-8 and bytes from [`OsStr::as_encoded_bytes`] from within the same Rust version
     /// built for the same target platform.  For example, reconstructing an `OsStr` from bytes sent
     /// over the network or stored in a file will likely violate these safety rules.
     ///
@@ -955,7 +955,7 @@ impl OsStr {
     /// ASCII.
     ///
     /// Note: As the encoding is unspecified, any sub-slice of bytes that is not valid UTF-8 should
-    /// be treated as opaque and only comparable within the same rust version built for the same
+    /// be treated as opaque and only comparable within the same Rust version built for the same
     /// target platform.  For example, sending the slice over the network or storing it in a file
     /// will likely result in incompatible byte slices.  See [`OsString`] for more encoding details
     /// and [`std::ffi`] for platform-specific, specified conversions.
diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index 694cc34cdc171..4373a1721e18e 100644
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -248,10 +248,10 @@ pub struct DirBuilder {
 ///
 /// ```no_run
 /// use std::fs;
-/// use std::net::SocketAddr;
 ///
 /// fn main() -> Result<(), Box<dyn std::error::Error + 'static>> {
-///     let foo: SocketAddr = String::from_utf8_lossy(&fs::read("address.txt")?).parse()?;
+///     let data: Vec<u8> = fs::read("image.jpg")?;
+///     assert_eq!(data[0..3], [0xFF, 0xD8, 0xFF]);
 ///     Ok(())
 /// }
 /// ```
@@ -290,11 +290,11 @@ pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
 ///
 /// ```no_run
 /// use std::fs;
-/// use std::net::SocketAddr;
 /// use std::error::Error;
 ///
 /// fn main() -> Result<(), Box<dyn Error>> {
-///     let foo: SocketAddr = fs::read_to_string("address.txt")?.parse()?;
+///     let message: String = fs::read_to_string("message.txt")?;
+///     println!("{}", message);
 ///     Ok(())
 /// }
 /// ```
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 288cce3aa085e..55a5292a4a41b 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -84,7 +84,7 @@
 //!
 //! # Contributing changes to the documentation
 //!
-//! Check out the rust contribution guidelines [here](
+//! Check out the Rust contribution guidelines [here](
 //! https://rustc-dev-guide.rust-lang.org/contributing.html#writing-documentation).
 //! The source for this documentation can be found on
 //! [GitHub](https://github.com/rust-lang/rust).
diff --git a/library/std/src/sys/pal/hermit/time.rs b/library/std/src/sys/pal/hermit/time.rs
index f289dafd8bc56..319b835a76879 100644
--- a/library/std/src/sys/pal/hermit/time.rs
+++ b/library/std/src/sys/pal/hermit/time.rs
@@ -179,7 +179,7 @@ impl Sub<Instant> for Instant {
     ///
     /// # Panics
     ///
-    /// Previous rust versions panicked when `other` was later than `self`. Currently this
+    /// Previous Rust versions panicked when `other` was later than `self`. Currently this
     /// method saturates. Future versions may reintroduce the panic in some circumstances.
     /// See [Monotonicity].
     ///
diff --git a/library/std/src/sys/pal/unix/stack_overflow.rs b/library/std/src/sys/pal/unix/stack_overflow.rs
index 923637cbaf260..78a599077c758 100644
--- a/library/std/src/sys/pal/unix/stack_overflow.rs
+++ b/library/std/src/sys/pal/unix/stack_overflow.rs
@@ -51,7 +51,7 @@ mod imp {
     #[cfg(all(target_os = "linux", target_env = "gnu"))]
     use libc::{mmap64, munmap};
     use libc::{sigaction, sighandler_t, SA_ONSTACK, SA_SIGINFO, SIGBUS, SIG_DFL};
-    use libc::{sigaltstack, SIGSTKSZ, SS_DISABLE};
+    use libc::{sigaltstack, SS_DISABLE};
     use libc::{MAP_ANON, MAP_PRIVATE, PROT_NONE, PROT_READ, PROT_WRITE, SIGSEGV};
 
     use crate::sync::atomic::{AtomicBool, AtomicPtr, Ordering};
@@ -130,7 +130,7 @@ mod imp {
         drop_handler(MAIN_ALTSTACK.load(Ordering::Relaxed));
     }
 
-    unsafe fn get_stackp() -> *mut libc::c_void {
+    unsafe fn get_stack() -> libc::stack_t {
         // OpenBSD requires this flag for stack mapping
         // otherwise the said mapping will fail as a no-op on most systems
         // and has a different meaning on FreeBSD
@@ -148,20 +148,28 @@ mod imp {
             target_os = "dragonfly",
         )))]
         let flags = MAP_PRIVATE | MAP_ANON;
-        let stackp =
-            mmap64(ptr::null_mut(), SIGSTKSZ + page_size(), PROT_READ | PROT_WRITE, flags, -1, 0);
+
+        let sigstack_size = sigstack_size();
+        let page_size = page_size();
+
+        let stackp = mmap64(
+            ptr::null_mut(),
+            sigstack_size + page_size,
+            PROT_READ | PROT_WRITE,
+            flags,
+            -1,
+            0,
+        );
         if stackp == MAP_FAILED {
             panic!("failed to allocate an alternative stack: {}", io::Error::last_os_error());
         }
-        let guard_result = libc::mprotect(stackp, page_size(), PROT_NONE);
+        let guard_result = libc::mprotect(stackp, page_size, PROT_NONE);
         if guard_result != 0 {
             panic!("failed to set up alternative stack guard page: {}", io::Error::last_os_error());
         }
-        stackp.add(page_size())
-    }
+        let stackp = stackp.add(page_size);
 
-    unsafe fn get_stack() -> libc::stack_t {
-        libc::stack_t { ss_sp: get_stackp(), ss_flags: 0, ss_size: SIGSTKSZ }
+        libc::stack_t { ss_sp: stackp, ss_flags: 0, ss_size: sigstack_size }
     }
 
     pub unsafe fn make_handler() -> Handler {
@@ -182,6 +190,8 @@ mod imp {
 
     pub unsafe fn drop_handler(data: *mut libc::c_void) {
         if !data.is_null() {
+            let sigstack_size = sigstack_size();
+            let page_size = page_size();
             let stack = libc::stack_t {
                 ss_sp: ptr::null_mut(),
                 ss_flags: SS_DISABLE,
@@ -189,14 +199,32 @@ mod imp {
                 // UNIX2003 which returns ENOMEM when disabling a stack while
                 // passing ss_size smaller than MINSIGSTKSZ. According to POSIX
                 // both ss_sp and ss_size should be ignored in this case.
-                ss_size: SIGSTKSZ,
+                ss_size: sigstack_size,
             };
             sigaltstack(&stack, ptr::null_mut());
             // We know from `get_stackp` that the alternate stack we installed is part of a mapping
             // that started one page earlier, so walk back a page and unmap from there.
-            munmap(data.sub(page_size()), SIGSTKSZ + page_size());
+            munmap(data.sub(page_size), sigstack_size + page_size);
         }
     }
+
+    /// Modern kernels on modern hardware can have dynamic signal stack sizes.
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    fn sigstack_size() -> usize {
+        // FIXME: reuse const from libc when available?
+        const AT_MINSIGSTKSZ: crate::ffi::c_ulong = 51;
+        let dynamic_sigstksz = unsafe { libc::getauxval(AT_MINSIGSTKSZ) };
+        // If getauxval couldn't find the entry, it returns 0,
+        // so take the higher of the "constant" and auxval.
+        // This transparently supports older kernels which don't provide AT_MINSIGSTKSZ
+        libc::SIGSTKSZ.max(dynamic_sigstksz as _)
+    }
+
+    /// Not all OS support hardware where this is needed.
+    #[cfg(not(any(target_os = "linux", target_os = "android")))]
+    fn sigstack_size() -> usize {
+        libc::SIGSTKSZ
+    }
 }
 
 #[cfg(not(any(
diff --git a/library/std/src/time.rs b/library/std/src/time.rs
index 91c010ef2b5e4..6f1a354d28a85 100644
--- a/library/std/src/time.rs
+++ b/library/std/src/time.rs
@@ -59,7 +59,7 @@ pub use core::time::TryFromFloatSecsError;
 /// experience time dilation (slow down or speed up), but it will never go
 /// backwards.
 /// As part of this non-guarantee it is also not specified whether system suspends count as
-/// elapsed time or not. The behavior varies across platforms and rust versions.
+/// elapsed time or not. The behavior varies across platforms and Rust versions.
 ///
 /// Instants are opaque types that can only be compared to one another. There is
 /// no method to get "the number of seconds" from an instant. Instead, it only
@@ -142,7 +142,7 @@ pub use core::time::TryFromFloatSecsError;
 /// where monotonicity is violated, or `Instant`s are subtracted in the wrong order.
 ///
 /// This workaround obscures programming errors where earlier and later instants are accidentally
-/// swapped. For this reason future rust versions may reintroduce panics.
+/// swapped. For this reason future Rust versions may reintroduce panics.
 ///
 /// [tier 1]: https://doc.rust-lang.org/rustc/platform-support.html
 /// [`duration_since`]: Instant::duration_since
@@ -290,7 +290,7 @@ impl Instant {
     ///
     /// # Panics
     ///
-    /// Previous rust versions panicked when `earlier` was later than `self`. Currently this
+    /// Previous Rust versions panicked when `earlier` was later than `self`. Currently this
     /// method saturates. Future versions may reintroduce the panic in some circumstances.
     /// See [Monotonicity].
     ///
@@ -365,7 +365,7 @@ impl Instant {
     ///
     /// # Panics
     ///
-    /// Previous rust versions panicked when the current time was earlier than self. Currently this
+    /// Previous Rust versions panicked when the current time was earlier than self. Currently this
     /// method returns a Duration of zero in that case. Future versions may reintroduce the panic.
     /// See [Monotonicity].
     ///
@@ -450,7 +450,7 @@ impl Sub<Instant> for Instant {
     ///
     /// # Panics
     ///
-    /// Previous rust versions panicked when `other` was later than `self`. Currently this
+    /// Previous Rust versions panicked when `other` was later than `self`. Currently this
     /// method saturates. Future versions may reintroduce the panic in some circumstances.
     /// See [Monotonicity].
     ///
diff --git a/library/test/src/formatters/terse.rs b/library/test/src/formatters/terse.rs
index 22c28e4954eff..875c66e5fa32c 100644
--- a/library/test/src/formatters/terse.rs
+++ b/library/test/src/formatters/terse.rs
@@ -84,7 +84,7 @@ impl<T: Write> TerseFormatter<T> {
         if self.test_column % QUIET_MODE_MAX_COLUMN == QUIET_MODE_MAX_COLUMN - 1 {
             // We insert a new line regularly in order to flush the
             // screen when dealing with line-buffered output (e.g., piping to
-            // `stamp` in the rust CI).
+            // `stamp` in the Rust CI).
             self.write_progress()?;
         }
 
diff --git a/library/test/src/types.rs b/library/test/src/types.rs
index 1a8ae889c8c1b..6a7035a8e2918 100644
--- a/library/test/src/types.rs
+++ b/library/test/src/types.rs
@@ -13,7 +13,7 @@ pub use NamePadding::*;
 pub use TestFn::*;
 pub use TestName::*;
 
-/// Type of the test according to the [rust book](https://doc.rust-lang.org/cargo/guide/tests.html)
+/// Type of the test according to the [Rust book](https://doc.rust-lang.org/cargo/guide/tests.html)
 /// conventions.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum TestType {
diff --git a/src/doc/rust.css b/src/doc/rust.css
index e0bf64c33bcf0..bd2e0b9451870 100644
--- a/src/doc/rust.css
+++ b/src/doc/rust.css
@@ -5,12 +5,13 @@ body {
 	margin: 0 auto;
 	padding: 0 15px;
 	font-size: 18px;
-	color: #333;
+	color: #000;
 	line-height: 1.428571429;
 
 	-webkit-box-sizing: unset;
 	-moz-box-sizing: unset;
 	box-sizing: unset;
+	background: #fff;
 }
 @media (min-width: 768px) {
 	body {
@@ -39,7 +40,6 @@ h4, h5, h6 {
 	padding: 5px 10px;
 }
 h5, h6 {
-	color: black;
 	text-decoration: underline;
 }
 
diff --git a/src/tools/miri/tests/compiletest.rs b/src/tools/miri/tests/compiletest.rs
index 9f46772456518..db0768848fd37 100644
--- a/src/tools/miri/tests/compiletest.rs
+++ b/src/tools/miri/tests/compiletest.rs
@@ -81,8 +81,10 @@ fn test_config(target: &str, path: &str, mode: Mode, with_dependencies: bool) ->
 
     // Add a test env var to do environment communication tests.
     program.envs.push(("MIRI_ENV_VAR_TEST".into(), Some("0".into())));
+
     // Let the tests know where to store temp files (they might run for a different target, which can make this hard to find).
-    program.envs.push(("MIRI_TEMP".into(), Some(env::temp_dir().into())));
+    let miri_temp = env::var_os("MIRI_TEMP").unwrap_or_else(|| env::temp_dir().into());
+    program.envs.push(("MIRI_TEMP".into(), Some(miri_temp)));
 
     let mut config = Config {
         target: Some(target.to_owned()),
diff --git a/src/tools/miri/tests/pass/shims/fs.rs b/src/tools/miri/tests/pass/shims/fs.rs
index 6ba39c1f563f9..304a178dc3404 100644
--- a/src/tools/miri/tests/pass/shims/fs.rs
+++ b/src/tools/miri/tests/pass/shims/fs.rs
@@ -1,6 +1,10 @@
 //@ignore-target-windows: File handling is not implemented yet
 //@compile-flags: -Zmiri-disable-isolation
 
+// If this test is failing for you locally, you can try
+// 1. Deleting the files `/tmp/miri_*`
+// 2. Setting `MIRI_TEMP` or `TMPDIR` to a different directory, without the `miri_*` files
+
 #![feature(io_error_more)]
 #![feature(io_error_uncategorized)]
 
diff --git a/src/tools/tidy/src/ui_tests.rs b/src/tools/tidy/src/ui_tests.rs
index a9c5be913ba1e..1a53637ad42f9 100644
--- a/src/tools/tidy/src/ui_tests.rs
+++ b/src/tools/tidy/src/ui_tests.rs
@@ -190,7 +190,11 @@ pub fn check(path: &Path, bless: bool, bad: &mut bool) {
         let blessed_issues_path = tidy_src.join("issues_blessed.txt");
         let mut blessed_issues_txt = fs::File::create(&blessed_issues_path).unwrap();
         blessed_issues_txt.write(issues_txt_header.as_bytes()).unwrap();
-        for filename in allowed_issue_names.difference(&remaining_issue_names) {
+        // If we changed paths to use the OS separator, reassert Unix chauvinism for blessing.
+        for filename in allowed_issue_names
+            .difference(&remaining_issue_names)
+            .map(|s| s.replace(std::path::MAIN_SEPARATOR_STR, "/"))
+        {
             write!(blessed_issues_txt, "\"{filename}\",\n").unwrap();
         }
         write!(blessed_issues_txt, "]\n").unwrap();
diff --git a/tests/codegen/vec-with-capacity.rs b/tests/codegen/vec-with-capacity.rs
new file mode 100644
index 0000000000000..47051f2eef891
--- /dev/null
+++ b/tests/codegen/vec-with-capacity.rs
@@ -0,0 +1,35 @@
+//@ compile-flags: -O
+//@ ignore-debug
+// (with debug assertions turned on, `assert_unchecked` generates a real assertion)
+
+#![crate_type = "lib"]
+#![feature(try_with_capacity)]
+
+// CHECK-LABEL: @with_capacity_does_not_grow1
+#[no_mangle]
+pub fn with_capacity_does_not_grow1() -> Vec<u32> {
+    let v = Vec::with_capacity(1234);
+    // CHECK: call {{.*}}__rust_alloc(
+    // CHECK-NOT: call {{.*}}__rust_realloc
+    // CHECK-NOT: call {{.*}}capacity_overflow
+    // CHECK-NOT: call {{.*}}finish_grow
+    // CHECK-NOT: call {{.*}}reserve
+    // CHECK-NOT: memcpy
+    // CHECK-NOT: memset
+    v
+}
+
+// CHECK-LABEL: @try_with_capacity_does_not_grow2
+#[no_mangle]
+pub fn try_with_capacity_does_not_grow2() -> Option<Vec<Vec<u8>>> {
+    let v = Vec::try_with_capacity(1234).ok()?;
+    // CHECK: call {{.*}}__rust_alloc(
+    // CHECK-NOT: call {{.*}}__rust_realloc
+    // CHECK-NOT: call {{.*}}capacity_overflow
+    // CHECK-NOT: call {{.*}}finish_grow
+    // CHECK-NOT: call {{.*}}handle_alloc_error
+    // CHECK-NOT: call {{.*}}reserve
+    // CHECK-NOT: memcpy
+    // CHECK-NOT: memset
+    Some(v)
+}
diff --git a/tests/ui/crate-loading/missing-std.stderr b/tests/ui/crate-loading/missing-std.stderr
index 70bcae1e0edd0..3eb6c2946d354 100644
--- a/tests/ui/crate-loading/missing-std.stderr
+++ b/tests/ui/crate-loading/missing-std.stderr
@@ -8,8 +8,6 @@ LL | extern crate core;
    = help: consider downloading the target with `rustup target add x86_64-unknown-uefi`
    = help: consider building the standard library from source with `cargo build -Zbuild-std`
 
-error: requires `sized` lang_item
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0463`.
diff --git a/tests/ui/hygiene/panic-location.run.stderr b/tests/ui/hygiene/panic-location.run.stderr
index 5c552411da7f3..ec0ce18c3dfa7 100644
--- a/tests/ui/hygiene/panic-location.run.stderr
+++ b/tests/ui/hygiene/panic-location.run.stderr
@@ -1,3 +1,3 @@
-thread 'main' panicked at library/alloc/src/raw_vec.rs:571:5:
+thread 'main' panicked at library/alloc/src/raw_vec.rs:26:5:
 capacity overflow
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
diff --git a/tests/ui/issues/issue-37131.stderr b/tests/ui/issues/issue-37131.stderr
index 9ecae3e7a2b24..588696f354184 100644
--- a/tests/ui/issues/issue-37131.stderr
+++ b/tests/ui/issues/issue-37131.stderr
@@ -4,8 +4,6 @@ error[E0463]: can't find crate for `std`
    = help: consider downloading the target with `rustup target add thumbv6m-none-eabi`
    = help: consider building the standard library from source with `cargo build -Zbuild-std`
 
-error: requires `sized` lang_item
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0463`.
diff --git a/tests/ui/issues/issue-49851/compiler-builtins-error.rs b/tests/ui/issues/issue-49851/compiler-builtins-error.rs
index 3b62cc73f93d6..db45d040f7914 100644
--- a/tests/ui/issues/issue-49851/compiler-builtins-error.rs
+++ b/tests/ui/issues/issue-49851/compiler-builtins-error.rs
@@ -1,5 +1,4 @@
 //~ ERROR can't find crate for `core`
-//~^ ERROR can't find crate for `compiler_builtins`
 
 //@ compile-flags: --target thumbv7em-none-eabihf
 //@ needs-llvm-components: arm
@@ -8,6 +7,5 @@
 #![no_std]
 
 extern crate cortex_m;
-//~^ ERROR can't find crate for `cortex_m`
 
 fn main() {}
diff --git a/tests/ui/issues/issue-49851/compiler-builtins-error.stderr b/tests/ui/issues/issue-49851/compiler-builtins-error.stderr
index fcfa2bf119cff..1cd65a1b68c88 100644
--- a/tests/ui/issues/issue-49851/compiler-builtins-error.stderr
+++ b/tests/ui/issues/issue-49851/compiler-builtins-error.stderr
@@ -4,16 +4,6 @@ error[E0463]: can't find crate for `core`
    = help: consider downloading the target with `rustup target add thumbv7em-none-eabihf`
    = help: consider building the standard library from source with `cargo build -Zbuild-std`
 
-error[E0463]: can't find crate for `compiler_builtins`
-
-error[E0463]: can't find crate for `cortex_m`
-  --> $DIR/compiler-builtins-error.rs:10:1
-   |
-LL | extern crate cortex_m;
-   | ^^^^^^^^^^^^^^^^^^^^^^ can't find crate
-
-error: requires `sized` lang_item
-
-error: aborting due to 4 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0463`.
diff --git a/tests/ui/panics/default-backtrace-ice.stderr b/tests/ui/panics/default-backtrace-ice.stderr
index 9d27cb22ae942..82b61e43f4494 100644
--- a/tests/ui/panics/default-backtrace-ice.stderr
+++ b/tests/ui/panics/default-backtrace-ice.stderr
@@ -21,5 +21,5 @@ error: the compiler unexpectedly panicked. this is a bug.
 
 
 query stack during panic:
-#0 [resolver_for_lowering] getting the resolver for lowering
+#0 [resolver_for_lowering_raw] getting the resolver for lowering
 end of query stack
diff --git a/tests/ui/parser/recover/recover-colon-instead-of-eq-in-local.rs b/tests/ui/parser/recover/recover-colon-instead-of-eq-in-local.rs
index ed4de58cd23ce..521eb6a818b0c 100644
--- a/tests/ui/parser/recover/recover-colon-instead-of-eq-in-local.rs
+++ b/tests/ui/parser/recover/recover-colon-instead-of-eq-in-local.rs
@@ -1,3 +1,10 @@
+#![allow(unused)]
+
+fn test_122112() {
+    // Make sure we don't ICE if parsing in recovery fails
+    let _: std::env::temp_dir().join(&self, push: Box<usize>);  //~ ERROR expected one of
+}
+
 fn main() {
     let _: std::env::temp_dir().join("foo"); //~ ERROR expected one of
 }
diff --git a/tests/ui/parser/recover/recover-colon-instead-of-eq-in-local.stderr b/tests/ui/parser/recover/recover-colon-instead-of-eq-in-local.stderr
index d03f3ae02830b..15c27bb9451b6 100644
--- a/tests/ui/parser/recover/recover-colon-instead-of-eq-in-local.stderr
+++ b/tests/ui/parser/recover/recover-colon-instead-of-eq-in-local.stderr
@@ -1,5 +1,13 @@
 error: expected one of `!`, `+`, `->`, `::`, `;`, or `=`, found `.`
-  --> $DIR/recover-colon-instead-of-eq-in-local.rs:2:32
+  --> $DIR/recover-colon-instead-of-eq-in-local.rs:5:32
+   |
+LL |     let _: std::env::temp_dir().join(&self, push: Box<usize>);
+   |          -                     ^ expected one of `!`, `+`, `->`, `::`, `;`, or `=`
+   |          |
+   |          while parsing the type for `_`
+
+error: expected one of `!`, `+`, `->`, `::`, `;`, or `=`, found `.`
+  --> $DIR/recover-colon-instead-of-eq-in-local.rs:9:32
    |
 LL |     let _: std::env::temp_dir().join("foo");
    |          -                     ^ expected one of `!`, `+`, `->`, `::`, `;`, or `=`
@@ -7,5 +15,5 @@ LL |     let _: std::env::temp_dir().join("foo");
    |          while parsing the type for `_`
    |          help: use `=` if you meant to assign
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/suggestions/deref-path-method.stderr b/tests/ui/suggestions/deref-path-method.stderr
index a2b68fa966fcb..b27d9aef06614 100644
--- a/tests/ui/suggestions/deref-path-method.stderr
+++ b/tests/ui/suggestions/deref-path-method.stderr
@@ -7,9 +7,9 @@ LL |     Vec::contains(&vec, &0);
 note: if you're trying to build a new `Vec<_, _>` consider using one of the following associated functions:
       Vec::<T>::new
       Vec::<T>::with_capacity
+      Vec::<T>::try_with_capacity
       Vec::<T>::from_raw_parts
-      Vec::<T, A>::new_in
-      and 2 others
+      and 4 others
   --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 help: the function `contains` is implemented on `[_]`
    |
diff --git a/tests/ui/transmute/transmute-zst-generics.rs b/tests/ui/transmute/transmute-zst-generics.rs
new file mode 100644
index 0000000000000..469ad632d4260
--- /dev/null
+++ b/tests/ui/transmute/transmute-zst-generics.rs
@@ -0,0 +1,14 @@
+// run-pass
+// Transmuting to/from ZSTs that contain generics.
+
+#![feature(transmute_generic_consts)]
+
+unsafe fn cast_zst<T>(from: ()) -> [T; 0] {
+    ::std::mem::transmute::<(), [T; 0]>(from)
+}
+
+pub fn main() {
+    unsafe {
+        let _: [u32; 0] = cast_zst(());
+    };
+}
diff --git a/tests/ui/ufcs/bad-builder.stderr b/tests/ui/ufcs/bad-builder.stderr
index e1c5e45b3ebb7..9cfeb7a5d09d6 100644
--- a/tests/ui/ufcs/bad-builder.stderr
+++ b/tests/ui/ufcs/bad-builder.stderr
@@ -7,9 +7,9 @@ LL |     Vec::<Q>::mew()
 note: if you're trying to build a new `Vec<Q>` consider using one of the following associated functions:
       Vec::<T>::new
       Vec::<T>::with_capacity
+      Vec::<T>::try_with_capacity
       Vec::<T>::from_raw_parts
-      Vec::<T, A>::new_in
-      and 2 others
+      and 4 others
   --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 help: there is an associated function `new` with a similar name
    |