diff --git a/compiler/rustc_codegen_llvm/src/builder/gpu_offload.rs b/compiler/rustc_codegen_llvm/src/builder/gpu_offload.rs
index 3d0bb6fcc48fd..d20a73e8e6825 100644
--- a/compiler/rustc_codegen_llvm/src/builder/gpu_offload.rs
+++ b/compiler/rustc_codegen_llvm/src/builder/gpu_offload.rs
@@ -197,6 +197,20 @@ fn generate_launcher<'ll>(cx: &CodegenCx<'ll, '_>) -> (&'ll llvm::Value, &'ll ll
     (tgt_decl, tgt_fn_ty)
 }
 
+/// Declares the `omp_get_num_devices` runtime function and returns the
+/// declaration together with its type.
+pub(crate) fn declare_omp_get_num_devices<'ll>(
+    cx: &CodegenCx<'ll, '_>,
+) -> (&'ll llvm::Value, &'ll llvm::Type) {
+    let ti32 = cx.type_i32();
+    let tgt_fn_ty = cx.type_func(&[], ti32);
+    let name = "omp_get_num_devices";
+    let tgt_decl = declare_offload_fn(&cx, name, tgt_fn_ty);
+    let nounwind = llvm::AttributeKind::NoUnwind.create_attr(cx.llcx);
+    attributes::apply_to_llfn(tgt_decl, Function, &[nounwind]);
+    (tgt_decl, tgt_fn_ty)
+}
+
 // What is our @1 here? A magic global, used in our data_{begin/update/end}_mapper:
 // @0 = private unnamed_addr constant [23 x i8] c";unknown;unknown;0;0;;\00", align 1
 // @1 = private unnamed_addr constant %struct.ident_t { i32 0, i32 2, i32 0, i32 22, ptr @0 }, align 8
@@ -591,6 +605,7 @@ pub(crate) fn gen_call_handling<'ll, 'tcx>(
     offload_globals: &OffloadGlobals<'ll>,
     offload_dims: &OffloadKernelDims<'ll>,
     dyn_cache: &'ll Value,
+    device_id: &'ll Value,
 ) {
     let cx = builder.cx;
     let OffloadKernelGlobals {
@@ -775,15 +790,8 @@ pub(crate) fn gen_call_handling<'ll, 'tcx>(
         builder.store(value.2, ptr, value.0);
     }
 
-    let args = vec![
-        s_ident_t,
-        // FIXME(offload) give users a way to select which GPU to use.
-        cx.get_const_i64(u64::MAX), // MAX == -1.
-        num_workgroups,
-        threads_per_block,
-        region_id,
-        a5,
-    ];
+    let device_id = builder.sext(device_id, cx.type_i64());
+    let args = vec![s_ident_t, device_id, num_workgroups, threads_per_block, region_id, a5];
     builder.call(tgt_target_kernel_ty, None, None, tgt_decl, &args, None, None);
     // %41 = call i32 @__tgt_target_kernel(ptr @1, i64 -1, i32 2097152, i32 256, ptr @.kernel_1.region_id, ptr %kernel_args)
 
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index ba11ef29fb536..a5bb595d9b2c6 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -37,7 +37,7 @@ use crate::abi::FnAbiLlvmExt;
 use crate::builder::Builder;
 use crate::builder::autodiff::{adjust_activity_to_abi, generate_enzyme_call};
 use crate::builder::gpu_offload::{
-    OffloadKernelDims, gen_call_handling, gen_define_handling, register_offload,
+    self, OffloadKernelDims, declare_omp_get_num_devices, register_offload,
 };
 use crate::context::CodegenCx;
 use crate::declare::declare_raw_fn;
@@ -241,6 +241,13 @@ impl<'ll, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
                 // offload *has* a return type, but somehow works without mentioning the place
                 return IntrinsicResult::WroteIntoPlace;
             }
+            sym::offload_get_num_devices => {
+                let (fn_decl, fn_ty) = declare_omp_get_num_devices(self.cx);
+
+                let llval = self.call(fn_ty, None, None, fn_decl, &[], None, None);
+
+                return IntrinsicResult::Operand(OperandValue::Immediate(llval));
+            },
             sym::is_val_statically_known => {
                 if let OperandValue::Immediate(imm) = args[0].val {
                     self.call_intrinsic(
@@ -1851,7 +1858,11 @@ fn codegen_offload<'ll, 'tcx>(
         OperandValue::Immediate(val) => val,
         _ => panic!("unparsable"),
     };
-    let args = get_args_from_tuple(bx, args[4], fn_target);
+    let device_id = match args[4].val {
+        OperandValue::Immediate(val) => val,
+        _ => panic!("unparsable"),
+    };
+    let args = get_args_from_tuple(bx, args[5], fn_target);
     let target_symbol = mangle_offload_export(tcx, fn_target);
 
     let sig = tcx.fn_sig(fn_target.def_id()).instantiate(tcx, fn_target.args).skip_norm_wip();
@@ -1882,8 +1893,9 @@ fn codegen_offload<'ll, 'tcx>(
         }
     };
     register_offload(cx);
-    let offload_data = gen_define_handling(&cx, &metadata, target_symbol, offload_globals);
-    gen_call_handling(
+    let offload_data =
+        gpu_offload::gen_define_handling(&cx, &metadata, target_symbol, offload_globals);
+    gpu_offload::gen_call_handling(
         bx,
         &offload_data,
         &args,
@@ -1892,6 +1904,7 @@ fn codegen_offload<'ll, 'tcx>(
         offload_globals,
         &offload_dims,
         &dyn_cache,
+        &device_id,
     );
 }
 
diff --git a/compiler/rustc_codegen_ssa/src/back/archive.rs b/compiler/rustc_codegen_ssa/src/back/archive.rs
index c4107b4a60f27..6c4575caebd8e 100644
--- a/compiler/rustc_codegen_ssa/src/back/archive.rs
+++ b/compiler/rustc_codegen_ssa/src/back/archive.rs
@@ -623,8 +623,9 @@ impl<'a> ArArchiveBuilder<'a> {
                             io::Error::new(
                                 io::ErrorKind::InvalidData,
                                 format!(
-                                    "archive member at offset {start} with size {} \
+                                    "archive member of {} at offset {start} with size {} \
                                          exceeds archive size {} in `{}`",
+                                    src_archive.0.display(),
                                     file_range.1,
                                     archive_data.len(),
                                     src_archive.0.display(),
@@ -642,11 +643,18 @@ impl<'a> ArArchiveBuilder<'a> {
                     }
                 }
                 ArchiveEntrySource::File(file) => unsafe {
-                    let mmap = Mmap::map(
-                        File::open(file)
-                            .map_err(|err| io_error_context("failed to open object file", err))?,
-                    )
-                    .map_err(|err| io_error_context("failed to map object file", err))?;
+                    let mmap = Mmap::map(File::open(&file).map_err(|err| {
+                        io_error_context(
+                            &format!("failed to open object file {}", file.display()),
+                            err,
+                        )
+                    })?)
+                    .map_err(|err| {
+                        io_error_context(
+                            &format!("failed to map object file {}", file.display()),
+                            err,
+                        )
+                    })?;
                     if entry.kind == ArchiveEntryKind::RustObj
                         && let Some(sym) = &symbols
                     {
diff --git a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
index d0820ad79902c..ed572b3774567 100644
--- a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
@@ -135,6 +135,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 | sym::atomic_fence
                 | sym::atomic_singlethreadfence
                 | sym::caller_location
+                | sym::offload_get_num_devices
                 | sym::return_address => {}
                 _ => {
                     span_bug!(
diff --git a/compiler/rustc_const_eval/src/check_consts/check.rs b/compiler/rustc_const_eval/src/check_consts/check.rs
index 7648bf4eb241d..b1efe62e57a04 100644
--- a/compiler/rustc_const_eval/src/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/check_consts/check.rs
@@ -49,69 +49,11 @@ pub(crate) struct Qualifs<'mir, 'tcx> {
 }
 
 impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
-    /// Returns `true` if `local` is `NeedsDrop` at the given `Location`.
-    ///
-    /// Only updates the cursor if absolutely necessary
-    pub(crate) fn needs_drop(
-        &mut self,
-        ccx: &'mir ConstCx<'mir, 'tcx>,
-        local: Local,
-        location: Location,
-    ) -> bool {
-        let ty = ccx.body.local_decls[local].ty;
-        // Peeking into opaque types causes cycles if the current function declares said opaque
-        // type. Thus we avoid short circuiting on the type and instead run the more expensive
-        // analysis that looks at the actual usage within this function
-        if !ty.has_opaque_types() && !NeedsDrop::in_any_value_of_ty(ccx, ty) {
-            return false;
-        }
-
-        let needs_drop = self.needs_drop.get_or_insert_with(|| {
-            let ConstCx { tcx, body, .. } = *ccx;
-
-            FlowSensitiveAnalysis::new(NeedsDrop, ccx)
-                .iterate_to_fixpoint(tcx, body, None)
-                .into_results_cursor(body)
-        });
-
-        needs_drop.seek_before_primary_effect(location);
-        needs_drop.get().contains(local)
-    }
-
-    /// Returns `true` if `local` is `NeedsNonConstDrop` at the given `Location`.
-    ///
-    /// Only updates the cursor if absolutely necessary
-    pub(crate) fn needs_non_const_drop(
-        &mut self,
-        ccx: &'mir ConstCx<'mir, 'tcx>,
-        local: Local,
-        location: Location,
-    ) -> bool {
-        let ty = ccx.body.local_decls[local].ty;
-        // Peeking into opaque types causes cycles if the current function declares said opaque
-        // type. Thus we avoid short circuiting on the type and instead run the more expensive
-        // analysis that looks at the actual usage within this function
-        if !ty.has_opaque_types() && !NeedsNonConstDrop::in_any_value_of_ty(ccx, ty) {
-            return false;
-        }
-
-        let needs_non_const_drop = self.needs_non_const_drop.get_or_insert_with(|| {
-            let ConstCx { tcx, body, .. } = *ccx;
-
-            FlowSensitiveAnalysis::new(NeedsNonConstDrop, ccx)
-                .iterate_to_fixpoint(tcx, body, None)
-                .into_results_cursor(body)
-        });
-
-        needs_non_const_drop.seek_before_primary_effect(location);
-        needs_non_const_drop.get().contains(local)
-    }
-
-    /// Returns `true` if `local` is `HasMutInterior` at the given `Location`.
+    /// Does `Q` hold for the `local` at the given `Location`?
     ///
     /// Only updates the cursor if absolutely necessary.
-    fn has_mut_interior(
-        &mut self,
+    fn in_local<Q: Qualif>(
+        qualif_results: &mut Option<QualifResults<'mir, 'tcx, Q>>,
         ccx: &'mir ConstCx<'mir, 'tcx>,
         local: Local,
         location: Location,
@@ -119,21 +61,21 @@ impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
         let ty = ccx.body.local_decls[local].ty;
         // Peeking into opaque types causes cycles if the current function declares said opaque
         // type. Thus we avoid short circuiting on the type and instead run the more expensive
-        // analysis that looks at the actual usage within this function
-        if !ty.has_opaque_types() && !HasMutInterior::in_any_value_of_ty(ccx, ty) {
+        // analysis that looks at the actual usage within this function.
+        if !ty.has_opaque_types() && !Q::in_any_value_of_ty(ccx, ty) {
             return false;
         }
 
-        let has_mut_interior = self.has_mut_interior.get_or_insert_with(|| {
+        let qualif_results = qualif_results.get_or_insert_with(|| {
             let ConstCx { tcx, body, .. } = *ccx;
 
-            FlowSensitiveAnalysis::new(HasMutInterior, ccx)
+            FlowSensitiveAnalysis::new(ccx)
                 .iterate_to_fixpoint(tcx, body, None)
                 .into_results_cursor(body)
         });
 
-        has_mut_interior.seek_before_primary_effect(location);
-        has_mut_interior.get().contains(local)
+        qualif_results.seek_before_primary_effect(location);
+        qualif_results.get().contains(local)
     }
 
     fn in_return_place(
@@ -161,9 +103,19 @@ impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
         let return_loc = ccx.body.terminator_loc(return_block);
 
         ConstQualifs {
-            needs_drop: self.needs_drop(ccx, RETURN_PLACE, return_loc),
-            needs_non_const_drop: self.needs_non_const_drop(ccx, RETURN_PLACE, return_loc),
-            has_mut_interior: self.has_mut_interior(ccx, RETURN_PLACE, return_loc),
+            needs_drop: Self::in_local(&mut self.needs_drop, ccx, RETURN_PLACE, return_loc),
+            needs_non_const_drop: Self::in_local(
+                &mut self.needs_non_const_drop,
+                ccx,
+                RETURN_PLACE,
+                return_loc,
+            ),
+            has_mut_interior: Self::in_local(
+                &mut self.has_mut_interior,
+                ccx,
+                RETURN_PLACE,
+                return_loc,
+            ),
             tainted_by_errors,
         }
     }
@@ -435,7 +387,7 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
         let ty_of_dropped_place = dropped_place.ty(self.body, self.tcx).ty;
 
         let needs_drop = if let Some(local) = dropped_place.as_local() {
-            self.qualifs.needs_drop(self.ccx, local, location)
+            Qualifs::in_local(&mut self.qualifs.needs_drop, self.ccx, local, location)
         } else {
             qualifs::NeedsDrop::in_any_value_of_ty(self.ccx, ty_of_dropped_place)
         };
@@ -448,7 +400,7 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
         let needs_non_const_drop = if let Some(local) = dropped_place.as_local() {
             // Use the span where the local was declared as the span of the drop error.
             err_span = self.body.local_decls[local].source_info.span;
-            self.qualifs.needs_non_const_drop(self.ccx, local, location)
+            Qualifs::in_local(&mut self.qualifs.needs_non_const_drop, self.ccx, local, location)
         } else {
             qualifs::NeedsNonConstDrop::in_any_value_of_ty(self.ccx, ty_of_dropped_place)
         };
@@ -602,7 +554,14 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
             | Rvalue::RawPtr(RawPtrKind::Const, place) => {
                 let borrowed_place_has_mut_interior = qualifs::in_place::<HasMutInterior, _>(
                     self.ccx,
-                    &mut |local| self.qualifs.has_mut_interior(self.ccx, local, location),
+                    &mut |local| {
+                        Qualifs::in_local(
+                            &mut self.qualifs.has_mut_interior,
+                            self.ccx,
+                            local,
+                            location,
+                        )
+                    },
                     place.as_ref(),
                 );
 
diff --git a/compiler/rustc_const_eval/src/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/check_consts/qualifs.rs
index b2b8a567860e0..daac2d5176258 100644
--- a/compiler/rustc_const_eval/src/check_consts/qualifs.rs
+++ b/compiler/rustc_const_eval/src/check_consts/qualifs.rs
@@ -45,10 +45,10 @@ pub trait Qualif {
     const ANALYSIS_NAME: &'static str;
 
     /// Whether this `Qualif` is cleared when a local is moved from.
-    const IS_CLEARED_ON_MOVE: bool = false;
+    const IS_CLEARED_ON_MOVE: bool;
 
     /// Whether this `Qualif` might be evaluated after the promotion and can encounter a promoted.
-    const ALLOW_PROMOTED: bool = false;
+    const ALLOW_PROMOTED: bool;
 
     /// Extracts the field of `ConstQualifs` that corresponds to this `Qualif`.
     fn in_qualifs(qualifs: &ConstQualifs) -> bool;
@@ -79,6 +79,8 @@ pub struct HasMutInterior;
 
 impl Qualif for HasMutInterior {
     const ANALYSIS_NAME: &'static str = "flow_has_mut_interior";
+    const IS_CLEARED_ON_MOVE: bool = false;
+    const ALLOW_PROMOTED: bool = false;
 
     fn in_qualifs(qualifs: &ConstQualifs) -> bool {
         qualifs.has_mut_interior
diff --git a/compiler/rustc_const_eval/src/check_consts/resolver.rs b/compiler/rustc_const_eval/src/check_consts/resolver.rs
index 29b6e26d950d5..4fc8c62ccf80a 100644
--- a/compiler/rustc_const_eval/src/check_consts/resolver.rs
+++ b/compiler/rustc_const_eval/src/check_consts/resolver.rs
@@ -247,7 +247,7 @@ impl<'mir, 'tcx, Q> FlowSensitiveAnalysis<'mir, 'tcx, Q>
 where
     Q: Qualif,
 {
-    pub(super) fn new(_: Q, ccx: &'mir ConstCx<'mir, 'tcx>) -> Self {
+    pub(super) fn new(ccx: &'mir ConstCx<'mir, 'tcx>) -> Self {
         FlowSensitiveAnalysis { ccx, _qualif: PhantomData }
     }
 
@@ -309,7 +309,7 @@ impl<C> DebugWithContext<C> for State {
 
         if self.borrow != old.borrow {
             f.write_str("borrow: ")?;
-            self.qualif.fmt_diff_with(&old.borrow, ctxt, f)?;
+            self.borrow.fmt_diff_with(&old.borrow, ctxt, f)?;
             f.write_str("\n")?;
         }
 
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 4dd8a4e3fe51d..0d7ff905300cc 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -168,6 +168,7 @@ fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hi
         | sym::needs_drop
         | sym::non_exhaustive
         | sym::offload
+        | sym::offload_get_num_devices
         | sym::offset_of
         | sym::overflow_checks
         | sym::powf16
@@ -384,10 +385,12 @@ pub(crate) fn check_intrinsic_type(
                 Ty::new_array_with_const_len(tcx, tcx.types.u32, Const::from_target_usize(tcx, 3)),
                 Ty::new_array_with_const_len(tcx, tcx.types.u32, Const::from_target_usize(tcx, 3)),
                 tcx.types.u32,
+                tcx.types.i32,
                 param(1),
             ],
             param(2),
         ),
+        sym::offload_get_num_devices => (0, 0, vec![], tcx.types.i32),
         sym::offset => (2, 0, vec![param(0), param(1)], param(0)),
         sym::arith_offset => (
             1,
diff --git a/compiler/rustc_hir_analysis/src/collect/dump.rs b/compiler/rustc_hir_analysis/src/collect/dump.rs
index b1b8b513f3b35..772bbe4a6b579 100644
--- a/compiler/rustc_hir_analysis/src/collect/dump.rs
+++ b/compiler/rustc_hir_analysis/src/collect/dump.rs
@@ -3,6 +3,7 @@ use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::{find_attr, intravisit};
 use rustc_middle::hir::nested_filter;
+use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
 use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt, Unnormalized};
 use rustc_span::sym;
 
@@ -25,6 +26,30 @@ pub(crate) fn generics(tcx: TyCtxt<'_>) {
     }
 }
 
+pub(crate) fn object_lifetime_defaults(tcx: TyCtxt<'_>) {
+    for def_id in tcx.hir_crate_items(()).definitions() {
+        if def_id == hir::def_id::CRATE_DEF_ID {
+            continue;
+        }
+
+        if !find_attr!(tcx, def_id, RustcDumpObjectLifetimeDefaults) {
+            continue;
+        }
+
+        for param in &tcx.generics_of(def_id).own_params {
+            let ty::GenericParamDefKind::Type { .. } = param.kind else { continue };
+            let default = tcx.object_lifetime_default(param.def_id);
+            let repr = match default {
+                ObjectLifetimeDefault::Empty => "Empty".to_owned(),
+                ObjectLifetimeDefault::Static => "'static".to_owned(),
+                ObjectLifetimeDefault::Param(def_id) => tcx.item_name(def_id).to_string(),
+                ObjectLifetimeDefault::Ambiguous => "Ambiguous".to_owned(),
+            };
+            tcx.dcx().span_err(tcx.def_span(param.def_id), repr);
+        }
+    }
+}
+
 pub(crate) fn opaque_hidden_types(tcx: TyCtxt<'_>) {
     if !find_attr!(tcx, crate, RustcDumpHiddenTypeOfOpaques) {
         return;
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs
index e5dbae16d07d4..7d07139a9077e 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs
@@ -2055,3 +2055,21 @@ fn assoc_tag_str(assoc_tag: ty::AssocTag) -> &'static str {
         ty::AssocTag::Type => "type",
     }
 }
+
+/// Computes the `pat.between(ty)` span for the "use `=`" suggestion on `let pat: ty`.
+/// Returns `None` if `pat` and `ty` are in incompatible macro contexts (e.g. `pat` is a
+/// metavariable from the call site while `ty` lives in the macro body), in which case no
+/// suggestion is emitted.
+pub(crate) fn eq_ctxt_suggestion_span(pat: Span, ty: Span) -> Option<Span> {
+    if let Some(ty2) = ty.find_ancestor_in_same_ctxt(pat)
+        && pat.hi() <= ty2.lo()
+    {
+        return Some(pat.between(ty2));
+    }
+    if let Some(pat2) = pat.find_ancestor_in_same_ctxt(ty)
+        && pat2.hi() <= ty.lo()
+    {
+        return Some(pat2.between(ty));
+    }
+    None
+}
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
index c65e9bdbd211e..8256ef6442057 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
@@ -56,7 +56,9 @@ use tracing::{debug, instrument};
 use crate::check::check_abi;
 use crate::check_c_variadic_abi;
 use crate::diagnostics::{self, BadReturnTypeNotation, NoFieldOnType, NoVariantNamed};
-use crate::hir_ty_lowering::errors::{GenericsArgsErrExtend, prohibit_assoc_item_constraint};
+use crate::hir_ty_lowering::errors::{
+    GenericsArgsErrExtend, eq_ctxt_suggestion_span, prohibit_assoc_item_constraint,
+};
 use crate::hir_ty_lowering::generics::{check_generic_arg_count, lower_generic_args};
 use crate::middle::resolve_bound_vars as rbv;
 
@@ -3302,18 +3304,18 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         .next()
                 {
                     // `let x: S::new(valid_in_ty_ctxt);` -> `let x = S::new(valid_in_ty_ctxt);`
-                    let err = tcx
-                        .dcx()
-                        .struct_span_err(
-                            hir_ty.span,
-                            "expected type, found associated function call",
-                        )
-                        .with_span_suggestion_verbose(
-                            stmt.pat.span.between(hir_ty.span),
+                    let mut err = tcx.dcx().struct_span_err(
+                        hir_ty.span,
+                        "expected type, found associated function call",
+                    );
+                    if let Some(between) = eq_ctxt_suggestion_span(stmt.pat.span, hir_ty.span) {
+                        err.span_suggestion_verbose(
+                            between,
                             "use `=` if you meant to assign",
-                            " = ".to_string(),
+                            " = ",
                             Applicability::MaybeIncorrect,
                         );
+                    }
                     self.dcx().try_steal_replace_and_emit_err(
                         hir_ty.span,
                         StashKey::ReturnTypeNotation,
@@ -3328,18 +3330,18 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 {
                     // `let x: i32::something(valid_in_ty_ctxt);` -> `let x = i32::something(valid_in_ty_ctxt);`
                     // FIXME: Check that `something` is a valid function in `i32`.
-                    let err = tcx
-                        .dcx()
-                        .struct_span_err(
-                            hir_ty.span,
-                            "expected type, found associated function call",
-                        )
-                        .with_span_suggestion_verbose(
-                            stmt.pat.span.between(hir_ty.span),
+                    let mut err = tcx.dcx().struct_span_err(
+                        hir_ty.span,
+                        "expected type, found associated function call",
+                    );
+                    if let Some(between) = eq_ctxt_suggestion_span(stmt.pat.span, hir_ty.span) {
+                        err.span_suggestion_verbose(
+                            between,
                             "use `=` if you meant to assign",
-                            " = ".to_string(),
+                            " = ",
                             Applicability::MaybeIncorrect,
                         );
+                    }
                     self.dcx().try_steal_replace_and_emit_err(
                         hir_ty.span,
                         StashKey::ReturnTypeNotation,
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index 572200dbd7634..7121b4b654cfe 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -203,13 +203,16 @@ pub fn check_crate(tcx: TyCtxt<'_>) {
 
     if tcx.features().rustc_attrs() {
         tcx.sess.time("dumping_rustc_attr_data", || {
-            outlives::dump::inferred_outlives(tcx);
-            variance::dump::variances(tcx);
-            collect::dump::generics(tcx);
-            collect::dump::opaque_hidden_types(tcx);
+            // tidy-alphabetical-start
             collect::dump::clauses_and_item_bounds(tcx);
             collect::dump::def_parents(tcx);
+            collect::dump::generics(tcx);
+            collect::dump::object_lifetime_defaults(tcx);
+            collect::dump::opaque_hidden_types(tcx);
             collect::dump::vtables(tcx);
+            outlives::dump::inferred_outlives(tcx);
+            variance::dump::variances(tcx);
+            // tidy-alphabetical-end
         });
     }
 
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index d9099cadaece8..1fe16d294433c 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -30,7 +30,6 @@ use rustc_hir::{
 };
 use rustc_macros::Diagnostic;
 use rustc_middle::hir::nested_filter;
-use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
 use rustc_middle::query::Providers;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
@@ -195,9 +194,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             AttributeKind::Deprecated { span: attr_span, .. } => {
                 self.check_deprecated(hir_id, *attr_span, target)
             }
-            AttributeKind::RustcDumpObjectLifetimeDefaults => {
-                self.check_dump_object_lifetime_defaults(hir_id);
-            }
             AttributeKind::Naked(..) => self.check_naked(hir_id, target),
             AttributeKind::NonExhaustive(attr_span) => {
                 self.check_non_exhaustive(*attr_span, span, target, item)
@@ -337,6 +333,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             AttributeKind::RustcDumpInferredOutlives => (),
             AttributeKind::RustcDumpItemBounds => (),
             AttributeKind::RustcDumpLayout(..) => (),
+            AttributeKind::RustcDumpObjectLifetimeDefaults => (),
             AttributeKind::RustcDumpSymbolName(..) => (),
             AttributeKind::RustcDumpUserArgs => (),
             AttributeKind::RustcDumpVariances => (),
@@ -785,23 +782,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Debugging aid for the `object_lifetime_default` query.
-    fn check_dump_object_lifetime_defaults(&self, hir_id: HirId) {
-        let tcx = self.tcx;
-        let Some(owner_id) = hir_id.as_owner() else { return };
-        for param in &tcx.generics_of(owner_id.def_id).own_params {
-            let ty::GenericParamDefKind::Type { .. } = param.kind else { continue };
-            let default = tcx.object_lifetime_default(param.def_id);
-            let repr = match default {
-                ObjectLifetimeDefault::Empty => "Empty".to_owned(),
-                ObjectLifetimeDefault::Static => "'static".to_owned(),
-                ObjectLifetimeDefault::Param(def_id) => tcx.item_name(def_id).to_string(),
-                ObjectLifetimeDefault::Ambiguous => "Ambiguous".to_owned(),
-            };
-            tcx.dcx().span_err(tcx.def_span(param.def_id), repr);
-        }
-    }
-
     /// Checks if the `#[non_exhaustive]` attribute on an `item` is valid.
     fn check_non_exhaustive(
         &self,
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index b67f0633fb772..693cdadec99fe 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1471,6 +1471,7 @@ symbols! {
         of,
         off,
         offload,
+        offload_get_num_devices,
         offload_kernel,
         offset,
         offset_of,
diff --git a/library/core/src/intrinsics/mod.rs b/library/core/src/intrinsics/mod.rs
index f5fab1e8614b5..2316fc4318918 100644
--- a/library/core/src/intrinsics/mod.rs
+++ b/library/core/src/intrinsics/mod.rs
@@ -3808,13 +3808,15 @@ pub const fn autodiff<F, G, T: crate::marker::Tuple, R>(f: F, df: G, args: T) ->
 /// - `f`: The kernel function to offload.
 /// - `workgroup_dim`: A 3D size specifying the number of workgroups to launch.
 /// - `thread_dim`: A 3D size specifying the number of threads per workgroup.
+/// - `dyn_cache`: The amount of dynamic shared memory to request for the kernel.
+/// - `device_id`: The device to offload to. Use `-1` to select the default device.
 /// - `args`: A tuple of arguments forwarded to `f`.
 ///
 /// Example usage (pseudocode):
 ///
 /// ```rust,ignore (pseudocode)
 /// fn kernel(x: *mut [f64; 128]) {
-///     core::intrinsics::offload(kernel_1, [256, 1, 1], [32, 1, 1], (x,))
+///     core::intrinsics::offload(kernel_1, [256, 1, 1], [32, 1, 1], 0, -1, (x,))
 /// }
 ///
 /// #[cfg(target_os = "linux")]
@@ -3838,9 +3840,20 @@ pub const fn offload<F, T: crate::marker::Tuple, R>(
     workgroup_dim: [u32; 3],
     thread_dim: [u32; 3],
     dyn_cache: u32,
+    device_id: i32,
     args: T,
 ) -> R;
 
+/// Returns the number of offload devices available on the system.
+///
+/// Use this to discover which `device_id` values are valid to pass to
+/// [`offload`]. Devices are numbered from `0` to the returned value minus one.
+///
+/// Returns `0` if no offloading devices are present.
+#[rustc_nounwind]
+#[rustc_intrinsic]
+pub const fn offload_get_num_devices() -> i32;
+
 /// Inform Miri that a given pointer definitely has a certain alignment.
 #[cfg(miri)]
 #[rustc_allow_const_fn_unstable(const_eval_select)]
diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
index 1664ce83aef72..6fac5cc11e1e4 100644
--- a/library/core/src/num/uint_macros.rs
+++ b/library/core/src/num/uint_macros.rs
@@ -515,8 +515,13 @@ macro_rules! uint_impl {
         ///
         /// # Panics
         ///
-        /// This function will panic if `n` is greater than or equal to the number of
-        /// bits in `self`.
+        /// ## Overflow behavior
+        ///
+        /// If overflow checks are enabled (default in debug mode), this function will panic if `n`
+        /// is greater than or equal to the number of bits in `self`. If overflow checks are
+        /// disabled (default in release mode), there is no panic; instead, the value is shifted
+        /// by `n % Self::BITS`.
+        // FIXME(wrapping_funnel_shifts): link to `wrapping_funnel_shl` when stable.
         ///
         /// # Examples
         ///
@@ -543,21 +548,31 @@ macro_rules! uint_impl {
         ///
         /// ```should_panic
         /// #![feature(funnel_shifts)]
+        /// # #![feature(cfg_overflow_checks)]
+        /// # #[cfg(overflow_checks)] {
         ///
         #[doc = concat!("let a = ", stringify!($SelfT), "::MAX;")]
         /// // Okay
         #[doc = concat!("let _ = a.rotate_left(", stringify!($SelfT), "::BITS);")]
-        /// // Panics
+        /// // Panics (only when overflow checks are enabled)
         #[doc = concat!("let _ = a.funnel_shl(a, ", stringify!($SelfT), "::BITS);")]
+        /// # }
+        /// # #[cfg(not(overflow_checks))] panic!("fulfill should_panic");
         /// ```
         #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
         #[unstable(feature = "funnel_shifts", issue = "145686")]
         #[must_use = "this returns the result of the operation, without modifying the original"]
         #[inline(always)]
+        #[rustc_inherit_overflow_checks]
         pub const fn funnel_shl(self, right: Self, n: u32) -> Self {
-            assert!(n < Self::BITS, "attempt to funnel shift left with overflow");
-            // SAFETY: just checked that `shift` is in-range
-            unsafe { self.unchecked_funnel_shl(right, n) }
+            if intrinsics::overflow_checks() {
+                assert!(n < Self::BITS, "attempt to funnel shift left with overflow");
+            }
+            // SAFETY: `n` is wrapped to within range
+            unsafe {
+                let n = n & (Self::BITS - 1);
+                self.unchecked_funnel_shl(right, n)
+            }
         }
 
         /// Performs a right funnel shift.
@@ -571,8 +586,13 @@ macro_rules! uint_impl {
         ///
         /// # Panics
         ///
-        /// This function will panic if `n` is greater than or equal to the number of
-        /// bits in `self`.
+        /// ## Overflow behavior
+        ///
+        /// If overflow checks are enabled (default in debug mode), this function will panic if `n`
+        /// is greater than or equal to the number of bits in `self`. If overflow checks are
+        /// disabled (default in release mode), there is no panic; instead, the value is shifted
+        /// by `n % Self::BITS`.
+        // FIXME(wrapping_funnel_shifts): link to `wrapping_funnel_shr` when stable.
         ///
         /// # Examples
         ///
@@ -599,21 +619,31 @@ macro_rules! uint_impl {
         ///
         /// ```should_panic
         /// #![feature(funnel_shifts)]
+        /// # #![feature(cfg_overflow_checks)]
+        /// # #[cfg(overflow_checks)] {
         ///
         #[doc = concat!("let a = ", stringify!($SelfT), "::MAX;")]
         /// // Okay
         #[doc = concat!("let _ = a.rotate_right(", stringify!($SelfT), "::BITS);")]
-        /// // Panics
+        /// // Panics (only when overflow checks are enabled)
         #[doc = concat!("let _ = a.funnel_shr(a, ", stringify!($SelfT), "::BITS);")]
+        /// # }
+        /// # #[cfg(not(overflow_checks))] panic!("fulfill should_panic");
         /// ```
         #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
         #[unstable(feature = "funnel_shifts", issue = "145686")]
         #[must_use = "this returns the result of the operation, without modifying the original"]
         #[inline(always)]
+        #[rustc_inherit_overflow_checks]
         pub const fn funnel_shr(self, right: Self, n: u32) -> Self {
-            assert!(n < Self::BITS, "attempt to funnel shift right with overflow");
-            // SAFETY: just checked that `shift` is in-range
-            unsafe { self.unchecked_funnel_shr(right, n) }
+            if intrinsics::overflow_checks() {
+                assert!(n < Self::BITS, "attempt to funnel shift right with overflow");
+            }
+            // SAFETY: `n` is wrapped to within range
+            unsafe {
+                let n = n & (Self::BITS - 1);
+                self.unchecked_funnel_shr(right, n)
+            }
         }
 
         /// Unchecked funnel shift left.
diff --git a/library/core/src/offload.md b/library/core/src/offload.md
index 985a93a4294fa..726d0c7af1928 100644
--- a/library/core/src/offload.md
+++ b/library/core/src/offload.md
@@ -21,7 +21,8 @@ fn kernel(x: *mut [f64; 256]) {
 ```
 
 To launch an offloaded kernel, use the `offload!` macro. It lets you specify the kernel, the
-workgroup and thread dimensions, and the arguments to forward to the device.
+workgroup and thread dimensions, the device to offload to, and the arguments to forward to the
+device.
 
 ```rust,ignore (optional component)
 let mut x = [0.0f64; 256];
diff --git a/library/core/src/offload/mod.rs b/library/core/src/offload/mod.rs
index 17ff74f0bbfbb..3d85621361209 100644
--- a/library/core/src/offload/mod.rs
+++ b/library/core/src/offload/mod.rs
@@ -19,6 +19,9 @@ pub use crate::offload;
 ///   Defaults to `[1, 1, 1]`.
 /// - `dyn_cache`: The amount of dynamic shared memory, in bytes, to allocate for the kernel.
 ///   Defaults to `0`.
+/// - `device`: The index of the device to offload to. Must be `>= 0`. If omitted, the
+///   default device is used. Use [`crate::intrinsics::offload_get_num_devices`] to discover
+///   which device ids are valid.
 ///
 /// Each argument may only be specified once.
 ///
@@ -43,61 +46,82 @@ macro_rules! offload {
             workgroup_dim = ([1, 1, 1]);
             thread_dim = ([1, 1, 1]);
             dyn_cache = (0);
+            device = NONE;
             args = NONE
         )
     };
 
-    (@munch [kernel = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = NONE; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; args = $a:tt) => {
-        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = (SOME $val); workgroup_dim = $w; thread_dim = $t; dyn_cache = $d; args = $a)
+    (@munch [kernel = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = NONE; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = $a:tt) => {
+        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = (SOME $val); workgroup_dim = $w; thread_dim = $t; dyn_cache = $d; device = $device; args = $a)
     };
-    (@munch [kernel = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = (SOME $old:expr); workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; args = $a:tt) => {
+    (@munch [kernel = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = (SOME $old:expr); workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = $a:tt) => {
         compile_error!("duplicate field `kernel`")
     };
-    (@munch [workgroup_dim = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = ([1, 1, 1]); thread_dim = $t:tt; dyn_cache = $d:tt; args = $a:tt) => {
-        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = (SOME $val); thread_dim = $t; dyn_cache = $d; args = $a)
+    (@munch [workgroup_dim = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = ([1, 1, 1]); thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = $a:tt) => {
+        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = (SOME $val); thread_dim = $t; dyn_cache = $d; device = $device; args = $a)
     };
-    (@munch [workgroup_dim = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = (SOME $old:expr); thread_dim = $t:tt; dyn_cache = $d:tt; args = $a:tt) => {
+    (@munch [workgroup_dim = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = (SOME $old:expr); thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = $a:tt) => {
         compile_error!("duplicate field `workgroup_dim`")
     };
-    (@munch [thread_dim = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = ([1, 1, 1]); dyn_cache = $d:tt; args = $a:tt) => {
-        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = $w; thread_dim = (SOME $val); dyn_cache = $d; args = $a)
+    (@munch [thread_dim = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = ([1, 1, 1]); dyn_cache = $d:tt; device = $device:tt; args = $a:tt) => {
+        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = $w; thread_dim = (SOME $val); dyn_cache = $d; device = $device; args = $a)
     };
-    (@munch [thread_dim = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = (SOME $old:expr); dyn_cache = $d:tt; args = $a:tt) => {
+    (@munch [thread_dim = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = (SOME $old:expr); dyn_cache = $d:tt; device = $device:tt; args = $a:tt) => {
         compile_error!("duplicate field `thread_dim`")
     };
-    (@munch [dyn_cache = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = (0); args = $a:tt) => {
-        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = $w; thread_dim = $t; dyn_cache = (SOME $val); args = $a)
+    (@munch [dyn_cache = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = (0); device = $device:tt; args = $a:tt) => {
+        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = $w; thread_dim = $t; dyn_cache = (SOME $val); device = $device; args = $a)
     };
-    (@munch [dyn_cache = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = (SOME $old:expr); args = $a:tt) => {
+    (@munch [dyn_cache = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = (SOME $old:expr); device = $device:tt; args = $a:tt) => {
         compile_error!("duplicate field `dyn_cache`")
     };
-    (@munch [args = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; args = NONE) => {
-        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = $w; thread_dim = $t; dyn_cache = $d; args = (SOME $val))
+    (@munch [device = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = NONE; args = $a:tt) => {
+        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = $w; thread_dim = $t; dyn_cache = $d; device = (SOME $val); args = $a)
     };
-    (@munch [args = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; args = (SOME $old:expr)) => {
+    (@munch [device = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = (SOME $old:expr); args = $a:tt) => {
+        compile_error!("duplicate field `device`")
+    };
+    (@munch [args = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = NONE) => {
+        $crate::offload!(@munch [$($rest_f = $rest_v),*]; kernel = $k; workgroup_dim = $w; thread_dim = $t; dyn_cache = $d; device = $device; args = (SOME $val))
+    };
+    (@munch [args = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = (SOME $old:expr)) => {
         compile_error!("duplicate field `args`")
     };
 
-    (@munch [$invalid:ident = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; args = $a:tt) => {
+    (@munch [$invalid:ident = $val:expr $(, $rest_f:ident = $rest_v:expr)*]; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = $a:tt) => {
         compile_error!(concat!("unknown field `", stringify!($invalid), "`"))
     };
 
-    (@munch []; kernel = NONE; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; args = $a:tt) => {
+    (@munch []; kernel = NONE; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = $a:tt) => {
         compile_error!("missing `kernel`")
     };
-    (@munch []; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; args = NONE) => {
+    (@munch []; kernel = $k:tt; workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = NONE) => {
         compile_error!("missing `args`")
     };
-    (@munch []; kernel = (SOME $kernel:expr); workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; args = (SOME $args:expr)) => {
+    (@munch []; kernel = (SOME $kernel:expr); workgroup_dim = $w:tt; thread_dim = $t:tt; dyn_cache = $d:tt; device = $device:tt; args = (SOME $args:expr)) => {
         $crate::intrinsics::offload::<_, _, ()>(
             $kernel,
             $crate::offload!(@value $w),
             $crate::offload!(@value $t),
             $crate::offload!(@value $d),
+            $crate::offload!(@device $device),
             $args,
         )
     };
 
     (@value (SOME $val:expr)) => { $val };
     (@value ($val:expr)) => { $val };
+
+    // if `device` is omitted (`NONE), we use the OpenMP default device (`-1`)
+    (@device NONE) => { -1 };
+    (@device (SOME $val:expr)) => { {
+        const { $crate::assert!($val >= 0, "offload device must be non-negative; omit `device` to use the default device") };
+        let device: i32 = $val;
+        $crate::assert!(
+            device < $crate::intrinsics::offload_get_num_devices(),
+            "offload device {} is not available",
+            device,
+        );
+        device
+    } };
 }
diff --git a/library/coretests/tests/lib.rs b/library/coretests/tests/lib.rs
index 1f629f01f38dd..10d760cd04ad2 100644
--- a/library/coretests/tests/lib.rs
+++ b/library/coretests/tests/lib.rs
@@ -11,6 +11,7 @@
 #![feature(borrowed_buf_init)]
 #![feature(bstr)]
 #![feature(casefold)]
+#![feature(cfg_overflow_checks)]
 #![feature(cfg_target_has_reliable_f16_f128)]
 #![feature(char_internals)]
 #![feature(clone_to_uninit)]
diff --git a/library/coretests/tests/num/uint_macros.rs b/library/coretests/tests/num/uint_macros.rs
index 8189776807915..37ad8a6b74185 100644
--- a/library/coretests/tests/num/uint_macros.rs
+++ b/library/coretests/tests/num/uint_macros.rs
@@ -216,17 +216,31 @@ macro_rules! uint_module {
         }
 
         #[test]
+        #[cfg(overflow_checks)]
         #[should_panic = "attempt to funnel shift left with overflow"]
         fn test_funnel_shl_overflow() {
             let _ = <$T>::funnel_shl(A, B, $T::BITS);
         }
 
         #[test]
+        #[cfg(overflow_checks)]
         #[should_panic = "attempt to funnel shift right with overflow"]
         fn test_funnel_shr_overflow() {
             let _ = <$T>::funnel_shr(A, B, $T::BITS);
         }
 
+        #[test]
+        #[cfg(not(overflow_checks))]
+        fn test_funnel_shl_overflow() {
+            let _ = <$T>::funnel_shl(A, B, A);
+        }
+
+        #[test]
+        #[cfg(not(overflow_checks))]
+        fn test_funnel_shr_overflow() {
+            let _ = <$T>::funnel_shr(A, B, B);
+        }
+
         #[test]
         fn test_funnel_shifts_runtime() {
             for i in 0..$T::BITS - 1 {
diff --git a/library/std/src/os/windows/process.rs b/library/std/src/os/windows/process.rs
index 41dcb70c59c9f..3949907888dd6 100644
--- a/library/std/src/os/windows/process.rs
+++ b/library/std/src/os/windows/process.rs
@@ -174,6 +174,15 @@ pub impl(self) trait CommandExt {
     #[stable(feature = "windows_process_extensions", since = "1.16.0")]
     fn creation_flags(&mut self, flags: u32) -> &mut process::Command;
 
+    /// Places the child process on the desktop named `desktop` by setting the
+    /// `lpDesktop` field of the [STARTUPINFO][1] passed to `CreateProcess`.
+    ///
+    /// The name may be a desktop or a `window-station\desktop` path.
+    ///
+    /// [1]: <https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/ns-processthreadsapi-startupinfow>
+    #[unstable(feature = "windows_process_extensions_desktop", issue = "158852")]
+    fn desktop<S: AsRef<OsStr>>(&mut self, desktop: S) -> &mut process::Command;
+
     /// Sets the field `wShowWindow` of [STARTUPINFO][1] that is passed to `CreateProcess`.
     /// Allowed values are the ones listed in
     /// <https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-showwindow>
@@ -383,6 +392,11 @@ impl CommandExt for process::Command {
         self
     }
 
+    fn desktop<S: AsRef<OsStr>>(&mut self, desktop: S) -> &mut process::Command {
+        self.as_inner_mut().desktop(desktop.as_ref());
+        self
+    }
+
     fn show_window(&mut self, cmd_show: u16) -> &mut process::Command {
         self.as_inner_mut().show_window(Some(cmd_show));
         self
diff --git a/library/std/src/sys/pal/unix/fuchsia.rs b/library/std/src/sys/pal/unix/fuchsia.rs
index c118dee624764..f9dfd52a610bb 100644
--- a/library/std/src/sys/pal/unix/fuchsia.rs
+++ b/library/std/src/sys/pal/unix/fuchsia.rs
@@ -9,12 +9,13 @@ use crate::io;
 // Time //
 //////////
 
-pub type zx_time_t = i64;
+pub type zx_instant_mono_t = i64;
 
-pub const ZX_TIME_INFINITE: zx_time_t = i64::MAX;
+pub const ZX_TIME_INFINITE: zx_instant_mono_t = i64::MAX;
 
 unsafe extern "C" {
-    pub safe fn zx_clock_get_monotonic() -> zx_time_t;
+    pub safe fn zx_clock_get_monotonic() -> zx_instant_mono_t;
+    pub safe fn zx_nanosleep(deadline: zx_instant_mono_t) -> zx_status_t;
 }
 
 /////////////
@@ -62,7 +63,7 @@ unsafe extern "C" {
     pub fn zx_object_wait_one(
         handle: zx_handle_t,
         signals: zx_signals_t,
-        timeout: zx_time_t,
+        deadline: zx_instant_mono_t,
         pending: *mut zx_signals_t,
     ) -> zx_status_t;
 
@@ -70,7 +71,7 @@ unsafe extern "C" {
         value_ptr: *const zx_futex_t,
         current_value: zx_futex_t,
         new_futex_owner: zx_handle_t,
-        deadline: zx_time_t,
+        deadline: zx_instant_mono_t,
     ) -> zx_status_t;
     pub fn zx_futex_wake(value_ptr: *const zx_futex_t, wake_count: u32) -> zx_status_t;
     pub fn zx_futex_wake_single_owner(value_ptr: *const zx_futex_t) -> zx_status_t;
@@ -117,7 +118,7 @@ pub type zx_info_process_flags_t = u32;
 #[repr(C)]
 pub struct zx_info_process_t {
     pub return_code: i64,
-    pub start_time: zx_time_t,
+    pub start_time: zx_instant_mono_t,
     pub flags: zx_info_process_flags_t,
     pub reserved1: u32,
 }
diff --git a/library/std/src/sys/process/windows.rs b/library/std/src/sys/process/windows.rs
index 0cff0fb7945c4..f095f829c4c67 100644
--- a/library/std/src/sys/process/windows.rs
+++ b/library/std/src/sys/process/windows.rs
@@ -162,6 +162,7 @@ pub struct Command {
     startupinfo_untrusted_source: bool,
     startupinfo_force_feedback: Option<bool>,
     inherit_handles: bool,
+    desktop: Option<Vec<u16>>,
 }
 
 pub enum Stdio {
@@ -191,6 +192,7 @@ impl Command {
             startupinfo_untrusted_source: false,
             startupinfo_force_feedback: None,
             inherit_handles: true,
+            desktop: None,
         }
     }
 
@@ -215,6 +217,7 @@ impl Command {
     pub fn creation_flags(&mut self, flags: u32) {
         self.flags = flags;
     }
+
     pub fn show_window(&mut self, cmd_show: Option<u16>) {
         self.show_window = cmd_show;
     }
@@ -239,6 +242,10 @@ impl Command {
         self.startupinfo_force_feedback = enabled;
     }
 
+    pub fn desktop(&mut self, desktop: &OsStr) {
+        self.desktop = Some(desktop.encode_wide().chain([0]).collect());
+    }
+
     pub fn get_program(&self) -> &OsStr {
         &self.program
     }
@@ -391,6 +398,10 @@ impl Command {
             None => {}
         }
 
+        if let Some(desktop) = &mut self.desktop {
+            si.lpDesktop = desktop.as_mut_ptr();
+        }
+
         let si_ptr: *mut c::STARTUPINFOW;
 
         let mut si_ex;
diff --git a/library/std/src/sys/thread/mod.rs b/library/std/src/sys/thread/mod.rs
index 9816981c7fc88..1ae0da23fe5e1 100644
--- a/library/std/src/sys/thread/mod.rs
+++ b/library/std/src/sys/thread/mod.rs
@@ -73,6 +73,7 @@ cfg_select! {
             target_os = "vxworks",
             target_os = "wasi",
             target_vendor = "apple",
+            target_os = "fuchsia",
         ))]
         pub use unix::sleep_until;
         #[expect(dead_code)]
@@ -134,7 +135,8 @@ cfg_select! {
     target_os = "wasi",
     target_vendor = "apple",
     target_os = "motor",
-    target_os = "vexos"
+    target_os = "vexos",
+    target_os = "fuchsia",
 )))]
 pub fn sleep_until(deadline: crate::time::Instant) {
     use crate::time::Instant;
diff --git a/library/std/src/sys/thread/unix.rs b/library/std/src/sys/thread/unix.rs
index 2dbb0314cb271..0de15cc27934f 100644
--- a/library/std/src/sys/thread/unix.rs
+++ b/library/std/src/sys/thread/unix.rs
@@ -650,6 +650,26 @@ pub fn sleep(dur: Duration) {
 pub fn sleep_until(deadline: crate::time::Instant) {
     use crate::time::Instant;
 
+    let timespec = deadline.into_inner().into_timespec();
+    if timespec.tv_sec < 0 {
+        // `clock_nanosleep` fails with EINVAL if
+        // > The tp argument to clock_settime() is outside the range for the
+        // > given clock ID.
+        //
+        // This specification allows *any* clock range, which means we'd
+        // theoretically have to detect whether the time point is in the
+        // future (and block indefinitely) or the past (and return immediately)
+        // when encountering `EINVAL`. But since all existing implementations
+        // interpret this as saying that negative `tv_sec` values are unsupported,
+        // we can just test that and return – given that POSIX specifies that
+        // `CLOCK_MONOTONIC` measures the time "since an unspecified amount
+        // in the past" negative values are definitely in the past. If you
+        // observe any platform returning `EINVAL` for more cases, please
+        // file a bug; we'd need to  add logic handling `EINVAL` when it
+        // occurs.
+        return;
+    }
+
     #[cfg(all(
         target_os = "linux",
         target_env = "gnu",
@@ -672,7 +692,7 @@ pub fn sleep_until(deadline: crate::time::Instant) {
         }
 
         if let Some(clock_nanosleep) = __clock_nanosleep_time64.get() {
-            let ts = deadline.into_inner().into_timespec().to_timespec64();
+            let ts = timespec.to_timespec64();
             loop {
                 let r = unsafe {
                     clock_nanosleep(
@@ -700,7 +720,7 @@ pub fn sleep_until(deadline: crate::time::Instant) {
         }
     }
 
-    let Some(ts) = deadline.into_inner().into_timespec().to_timespec() else {
+    let Some(ts) = timespec.to_timespec() else {
         // The deadline is further in the future then can be passed to
         // clock_nanosleep. We have to use Self::sleep instead. This might
         // happen on 32 bit platforms, especially closer to 2038.
@@ -778,6 +798,16 @@ pub fn sleep_until(deadline: crate::time::Instant) {
     }
 }
 
+#[cfg(target_os = "fuchsia")]
+pub fn sleep_until(deadline: crate::time::Instant) {
+    use crate::sys::pal::fuchsia::{zx_cvt, zx_nanosleep};
+
+    let deadline = deadline.into_inner().into_deadline();
+    if let Err(error) = zx_cvt(zx_nanosleep(deadline)) {
+        panic!("zx_nanosleep failed: {error}");
+    }
+}
+
 pub fn yield_now() {
     let ret = unsafe { libc::sched_yield() };
     debug_assert_eq!(ret, 0);
diff --git a/library/std/src/sys/time/unix.rs b/library/std/src/sys/time/unix.rs
index 944cb552cad9e..d84256df0cd53 100644
--- a/library/std/src/sys/time/unix.rs
+++ b/library/std/src/sys/time/unix.rs
@@ -123,6 +123,11 @@ impl Instant {
         // 126 bits.
         Some((nanos * u128::from(timebase.denom)).div_ceil(u128::from(timebase.numer)))
     }
+
+    #[cfg(target_os = "fuchsia")]
+    pub fn into_deadline(self) -> crate::sys::pal::fuchsia::zx_instant_mono_t {
+        self.t.tv_sec.saturating_mul(1_000_000_000).saturating_add(self.t.tv_nsec.as_inner().into())
+    }
 }
 
 impl AsInner<Timespec> for Instant {
diff --git a/library/std/src/thread/functions.rs b/library/std/src/thread/functions.rs
index 355a00c2a95ad..19e830facd5ec 100644
--- a/library/std/src/thread/functions.rs
+++ b/library/std/src/thread/functions.rs
@@ -295,9 +295,10 @@ pub fn sleep(dur: Duration) {
 
 /// Puts the current thread to sleep until the specified deadline has passed.
 ///
-/// The thread may still be asleep after the deadline specified due to
-/// scheduling specifics or platform-dependent functionality. It will never
-/// wake before.
+/// If the deadline has already passed at the time this function is called, it
+/// will return immediately. Note that the thread may still be asleep after the
+/// deadline specified due to scheduling specifics or platform-dependent
+/// functionality. It will never wake before.
 ///
 /// This function is blocking, and should not be used in `async` functions.
 ///
@@ -313,19 +314,21 @@ pub fn sleep(dur: Duration) {
 ///
 /// |  Platform |               System call                                            |
 /// |-----------|----------------------------------------------------------------------|
-/// | Linux     | [clock_nanosleep] (Monotonic Clock)                                  |
-/// | BSD except OpenBSD | [clock_nanosleep] (Monotonic Clock)                         |
-/// | Android   | [clock_nanosleep] (Monotonic Clock)                                  |
-/// | Solaris   | [clock_nanosleep] (Monotonic Clock)                                  |
-/// | Illumos   | [clock_nanosleep] (Monotonic Clock)                                  |
-/// | Dragonfly | [clock_nanosleep] (Monotonic Clock)                                  |
-/// | Hurd      | [clock_nanosleep] (Monotonic Clock)                                  |
-/// | Vxworks   | [clock_nanosleep] (Monotonic Clock)                                  |
+/// | Linux     | [`clock_nanosleep`] (Monotonic Clock)                                |
+/// | BSD except OpenBSD | [`clock_nanosleep`] (Monotonic Clock)                       |
+/// | Android   | [`clock_nanosleep`] (Monotonic Clock)                                |
+/// | Solaris   | [`clock_nanosleep`] (Monotonic Clock)                                |
+/// | Illumos   | [`clock_nanosleep`] (Monotonic Clock)                                |
+/// | Dragonfly | [`clock_nanosleep`] (Monotonic Clock)                                |
+/// | Hurd      | [`clock_nanosleep`] (Monotonic Clock)                                |
+/// | Vxworks   | [`clock_nanosleep`] (Monotonic Clock)                                |
 /// | Apple     | `mach_wait_until`                                                    |
+/// | Fuchsia   | [`zx_nanosleep`]                                                     |
 /// | Other     | `sleep_until` uses [`sleep`] and does not issue a syscall itself     |
 ///
 /// [currently]: crate::io#platform-specific-behavior
-/// [clock_nanosleep]: https://linux.die.net/man/3/clock_nanosleep
+/// [`clock_nanosleep`]: https://linux.die.net/man/3/clock_nanosleep
+/// [`zx_nanosleep`]: https://fuchsia.dev/reference/syscalls/nanosleep
 ///
 /// **Disclaimer:** These system calls might change over time.
 ///
diff --git a/library/std/src/thread/tests.rs b/library/std/src/thread/tests.rs
index 78b6f7c35e8db..e88ca92218dc8 100644
--- a/library/std/src/thread/tests.rs
+++ b/library/std/src/thread/tests.rs
@@ -333,6 +333,15 @@ fn sleep_ms_smoke() {
     thread::sleep(Duration::from_millis(2));
 }
 
+#[test]
+fn sleep_until_elapsed() {
+    // UNIX's `clock_nanosleep` doesn't like timeouts that are too far back.
+    // Test that `sleep_until` returns immediately instead of panicking.
+    // Going 10 years back should be enough to trigger any errors.
+    let earlier = Instant::now() - Duration::from_secs(10 * 365 * 24 * 3600);
+    thread::sleep_until(earlier);
+}
+
 #[test]
 fn test_size_of_option_thread_id() {
     assert_eq!(size_of::<Option<ThreadId>>(), size_of::<ThreadId>());
diff --git a/library/unwind/src/types.rs b/library/unwind/src/types.rs
index 7634052c93f33..d745b836e822b 100644
--- a/library/unwind/src/types.rs
+++ b/library/unwind/src/types.rs
@@ -42,6 +42,12 @@ pub const unwinder_private_data_size: usize = cfg_select! {
 };
 
 #[repr(C)]
+// The Itanium C++ ABI requires this type to have "double-word" alignment,
+// which libunwind and libgcc interpret as the maximum alignment of any
+// scalar type on the current target.
+#[cfg_attr(target_pointer_width = "16", repr(align(4)))]
+#[cfg_attr(target_pointer_width = "32", repr(align(8)))]
+#[cfg_attr(target_pointer_width = "64", repr(align(16)))]
 pub struct _Unwind_Exception {
     pub exception_class: _Unwind_Exception_Class,
     pub exception_cleanup: _Unwind_Exception_Cleanup_Fn,
diff --git a/src/bootstrap/src/cli_main.rs b/src/bootstrap/src/cli_main.rs
index c11e1478f4d42..8a74b2e598283 100644
--- a/src/bootstrap/src/cli_main.rs
+++ b/src/bootstrap/src/cli_main.rs
@@ -16,11 +16,12 @@ use std::{env, process};
 use crate::core::builder::StepStack;
 use crate::core::config::flags::{Flags, Subcommand};
 use crate::core::config::{ChangeId, Config};
+use crate::core::session::Build;
+use crate::debug;
 use crate::utils::change_tracker::{
     CONFIG_CHANGE_HISTORY, find_recent_config_change_ids, human_readable_changes,
 };
 use crate::utils::helpers::t;
-use crate::{Build, debug};
 
 fn is_tracing_enabled() -> bool {
     cfg!(feature = "tracing")
diff --git a/src/bootstrap/src/core/build_steps/check.rs b/src/bootstrap/src/core/build_steps/check.rs
index 265999711eb87..4a75cdbb1562f 100644
--- a/src/bootstrap/src/core/build_steps/check.rs
+++ b/src/bootstrap/src/core/build_steps/check.rs
@@ -3,7 +3,6 @@
 use std::fs;
 use std::path::{Path, PathBuf};
 
-use crate::Mode;
 use crate::core::backend::CodegenBackendKind;
 use crate::core::build_steps::compile::{
     ArtifactKeepMode, add_to_sysroot, run_cargo, rustc_cargo, rustc_cargo_env, std_cargo,
@@ -20,6 +19,7 @@ use crate::core::builder::{
 };
 use crate::core::compiler::Compiler;
 use crate::core::config::TargetSelection;
+use crate::core::session::Mode;
 use crate::utils::build_stamp::{self, BuildStamp};
 use crate::utils::helpers::t;
 
diff --git a/src/bootstrap/src/core/build_steps/clean.rs b/src/bootstrap/src/core/build_steps/clean.rs
index a5c7398d11302..23f12bbb63e72 100644
--- a/src/bootstrap/src/core/build_steps/clean.rs
+++ b/src/bootstrap/src/core/build_steps/clean.rs
@@ -14,9 +14,9 @@ use crate::core::builder::{
 };
 use crate::core::compiler::Compiler;
 use crate::core::config::flags::Subcommand;
+use crate::core::session::{Build, Mode};
 use crate::utils::build_stamp::BuildStamp;
 use crate::utils::helpers::t;
-use crate::{Build, Mode};
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct CleanAll {}
diff --git a/src/bootstrap/src/core/build_steps/clippy.rs b/src/bootstrap/src/core/build_steps/clippy.rs
index 2ca775f92d683..dc3e3efb80ee5 100644
--- a/src/bootstrap/src/core/build_steps/clippy.rs
+++ b/src/bootstrap/src/core/build_steps/clippy.rs
@@ -14,7 +14,6 @@
 //! (as usual) a massive undertaking/refactoring.
 
 use super::tool::{SourceType, prepare_tool_cargo};
-use crate::Mode;
 use crate::core::build_steps::check::{CompilerForCheck, prepare_compiler_for_check};
 use crate::core::build_steps::compile::{
     ArtifactKeepMode, run_cargo, rustc_cargo, std_cargo, std_crates_for_make_run,
@@ -26,6 +25,7 @@ use crate::core::builder::{
 use crate::core::compiler::Compiler;
 use crate::core::config::TargetSelection;
 use crate::core::config::flags::Subcommand;
+use crate::core::session::Mode;
 use crate::utils::build_stamp::{self, BuildStamp};
 use crate::utils::helpers;
 
diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index c008ff5090a9c..fcf8be30c9dd1 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -33,13 +33,14 @@ use crate::core::config::toml::target::DefaultLinuxLinkerOverride;
 use crate::core::config::{
     Allocator, CompilerBuiltins, DebuginfoLevel, LlvmLibunwind, RustcLto, TargetSelection,
 };
+use crate::core::session::{CLang, DependencyType, FileType, GitRepo, Mode};
 use crate::utils::build_stamp;
 use crate::utils::build_stamp::BuildStamp;
 use crate::utils::exec::command;
 use crate::utils::helpers::{
     self, exe, get_clang_cl_resource_dir, is_debug_info, is_dylib, symlink_dir, t, up_to_date,
 };
-use crate::{CLang, DependencyType, FileType, GitRepo, Mode, debug, trace};
+use crate::{debug, trace};
 
 /// Build a standard library for the given `target` using the given `build_compiler`.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index b5118281fab74..5c86d117767c8 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -38,6 +38,8 @@ use crate::core::builder::{
 };
 use crate::core::compiler::Compiler;
 use crate::core::config::{GccCiMode, TargetSelection};
+use crate::core::session::{DependencyType, FileType, Mode};
+use crate::trace;
 use crate::utils::build_stamp::{self, BuildStamp};
 use crate::utils::channel::{self, Info};
 use crate::utils::exec::{BootstrapCommand, command};
@@ -45,7 +47,6 @@ use crate::utils::helpers::{
     exe, is_dylib, move_file, t, target_supports_cranelift_backend, timeit,
 };
 use crate::utils::tarball::{GeneratedTarball, OverlayKind, Tarball};
-use crate::{DependencyType, FileType, Mode, trace};
 
 pub(crate) const LLVM_TOOLS: &[&str] = &[
     "llvm-cov",      // used to generate coverage report
diff --git a/src/bootstrap/src/core/build_steps/doc.rs b/src/bootstrap/src/core/build_steps/doc.rs
index adff654fe88e8..b80a0b0ba27c8 100644
--- a/src/bootstrap/src/core/build_steps/doc.rs
+++ b/src/bootstrap/src/core/build_steps/doc.rs
@@ -21,8 +21,8 @@ use crate::core::builder::{
 };
 use crate::core::compiler::Compiler;
 use crate::core::config::{Config, TargetSelection};
+use crate::core::session::{FileType, Mode};
 use crate::utils::helpers::{submodule_path_of, symlink_dir, t, up_to_date};
-use crate::{FileType, Mode};
 
 macro_rules! book {
     ($($name:ident, $path:expr, $book_name:expr, $lang:expr ;)+) => {
diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
index 323cce1da51ab..5d188bcd25570 100644
--- a/src/bootstrap/src/core/build_steps/llvm.rs
+++ b/src/bootstrap/src/core/build_steps/llvm.rs
@@ -21,12 +21,13 @@ use crate::core::builder::{
     Builder, CommandLineStep, Kind, RunConfig, ShouldRun, Step, StepMetadata,
 };
 use crate::core::config::{Config, LlvmCiMode, LlvmPgoGenerationMode, TargetSelection};
+use crate::core::session::{CLang, GitRepo};
+use crate::trace;
 use crate::utils::build_stamp::{BuildStamp, generate_smart_stamp_hash};
 use crate::utils::exec::command;
 use crate::utils::helpers::{
     self, exe, get_clang_cl_resource_dir, libdir, t, unhashed_basename, up_to_date,
 };
-use crate::{CLang, GitRepo, trace};
 
 /// Path where a file containing the link type (dynamic or static) is stored in the LLVM CI tarball.
 pub const LLVM_CI_LINK_TYPE_PATH: &str = "link-type.txt";
diff --git a/src/bootstrap/src/core/build_steps/run.rs b/src/bootstrap/src/core/build_steps/run.rs
index 82a132d0b5288..243b09acaa308 100644
--- a/src/bootstrap/src/core/build_steps/run.rs
+++ b/src/bootstrap/src/core/build_steps/run.rs
@@ -8,7 +8,6 @@ use std::path::PathBuf;
 use build_helper::git::get_git_untracked_files;
 use clap_complete::{Generator, shells};
 
-use crate::Mode;
 use crate::core::build_steps::dist::distdir;
 use crate::core::build_steps::test;
 use crate::core::build_steps::tool::{self, RustcPrivateCompilers, SourceType, Tool};
@@ -16,6 +15,7 @@ use crate::core::build_steps::vendor::{VENDOR_DIR, Vendor, default_paths_to_vend
 use crate::core::builder::{Builder, CommandLineStep, Kind, RunConfig, ShouldRun, StepMetadata};
 use crate::core::config::TargetSelection;
 use crate::core::config::flags::{get_completion, top_level_help};
+use crate::core::session::Mode;
 use crate::utils::exec::command;
 use crate::utils::helpers::{self, t};
 
diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index a4eefe51c420e..be3dc2954086c 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -38,6 +38,7 @@ use crate::core::builder::{
 use crate::core::compiler::Compiler;
 use crate::core::config::TargetSelection;
 use crate::core::config::flags::{Subcommand, get_completion, top_level_help};
+use crate::core::session::{CLang, GitRepo, Mode};
 use crate::core::{android, debuggers};
 use crate::utils::build_stamp::{self, BuildStamp};
 use crate::utils::exec::{BootstrapCommand, command};
@@ -47,7 +48,6 @@ use crate::utils::helpers::{
     target_supports_cranelift_backend, up_to_date,
 };
 use crate::utils::render_tests::{add_flags_and_try_run_tests, try_run_tests};
-use crate::{CLang, GitRepo, Mode};
 
 mod compiletest;
 pub mod failed_tests;
diff --git a/src/bootstrap/src/core/build_steps/tool.rs b/src/bootstrap/src/core/build_steps/tool.rs
index b67d1b1bd49e7..4e94a422fd153 100644
--- a/src/bootstrap/src/core/build_steps/tool.rs
+++ b/src/bootstrap/src/core/build_steps/tool.rs
@@ -23,9 +23,9 @@ use crate::core::builder::{
 };
 use crate::core::compiler::Compiler;
 use crate::core::config::{Allocator, DebuginfoLevel, RustcLto, TargetSelection};
+use crate::core::session::{FileType, Mode};
 use crate::utils::exec::{BootstrapCommand, command};
 use crate::utils::helpers::{self, add_dylib_path, exe, t};
-use crate::{FileType, Mode};
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub enum SourceType {
diff --git a/src/bootstrap/src/core/builder/cargo.rs b/src/bootstrap/src/core/builder/cargo.rs
index f5c28c8e0445e..7b621a2ecc834 100644
--- a/src/bootstrap/src/core/builder/cargo.rs
+++ b/src/bootstrap/src/core/builder/cargo.rs
@@ -11,10 +11,10 @@ use crate::core::compiler::Compiler;
 use crate::core::config::flags::{Color, Subcommand};
 use crate::core::config::toml::pgo::PgoConfig;
 use crate::core::config::{CompressDebuginfo, Config, DryRun, SplitDebuginfo, TargetSelection};
+use crate::core::session::{CLang, GitRepo, Mode, RemapScheme};
 use crate::utils::build_stamp;
 use crate::utils::exec::{BootstrapCommand, command};
 use crate::utils::helpers::{self, LldThreads, check_cfg_arg, envify, linker_flags, t};
-use crate::{CLang, GitRepo, Mode, RemapScheme};
 
 /// Extra `--check-cfg` to add when building the compiler or tools
 /// (Mode restriction, config name, config values (if any))
diff --git a/src/bootstrap/src/core/builder/cli_paths/tests.rs b/src/bootstrap/src/core/builder/cli_paths/tests.rs
index e18a274c75f49..3a92bf37bdf0a 100644
--- a/src/bootstrap/src/core/builder/cli_paths/tests.rs
+++ b/src/bootstrap/src/core/builder/cli_paths/tests.rs
@@ -2,8 +2,8 @@ use std::collections::{BTreeSet, HashSet};
 use std::path::PathBuf;
 use std::sync::{Arc, Mutex};
 
-use crate::Build;
 use crate::core::builder::{Builder, CommandLineStepDescription};
+use crate::core::session::Build;
 use crate::utils::tests::TestCtx;
 
 fn render_steps_for_cli_args(args_str: &str) -> String {
diff --git a/src/bootstrap/src/core/builder/mod.rs b/src/bootstrap/src/core/builder/mod.rs
index 6f30f3b56f8b8..98fceeae9df5c 100644
--- a/src/bootstrap/src/core/builder/mod.rs
+++ b/src/bootstrap/src/core/builder/mod.rs
@@ -25,12 +25,13 @@ use crate::core::compiler::Compiler;
 use crate::core::config::flags::Subcommand;
 use crate::core::config::{DryRun, TargetSelection};
 use crate::core::metadata::Crate;
+use crate::core::session::Build;
+use crate::trace;
 use crate::utils::build_stamp::BuildStamp;
 use crate::utils::cache::Cache;
 use crate::utils::exec::{BootstrapCommand, ExecutionContext, command};
 use crate::utils::helpers::{self, LldThreads, add_dylib_path, exe, libdir, linker_args, t};
 use crate::utils::tracing::format_location;
-use crate::{Build, trace};
 
 mod cargo;
 mod cli_paths;
@@ -40,7 +41,7 @@ mod tests;
 
 /// Builds and performs different [`Self::kind`]s of stuff and actions, taking
 /// into account build configuration from e.g. bootstrap.toml.
-pub struct Builder<'a> {
+pub(crate) struct Builder<'a> {
     /// Build configuration from e.g. bootstrap.toml.
     pub build: &'a Build,
 
diff --git a/src/bootstrap/src/core/compiler.rs b/src/bootstrap/src/core/compiler.rs
index a57c60465f24c..5602e8ffd1efd 100644
--- a/src/bootstrap/src/core/compiler.rs
+++ b/src/bootstrap/src/core/compiler.rs
@@ -1,7 +1,7 @@
 use std::hash::{Hash, Hasher};
 
-use crate::Build;
 use crate::core::config::TargetSelection;
+use crate::core::session::Build;
 
 /// A structure representing a Rust compiler.
 ///
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index 8ca1c74b929e3..f74def6a61d8b 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -1845,7 +1845,7 @@ NOTE: Please add `--stage 2` to your command line, or if you're sure you want to
     ///
     /// This *does not* update the submodule if `bootstrap.toml` explicitly says
     /// not to, or if we're not in a git repository (like a plain source
-    /// tarball). Typically [`crate::Build::require_submodule`] should be
+    /// tarball). Typically [`crate::core::session::Build::require_submodule`] should be
     /// used instead to provide a nice error to the user if the submodule is
     /// missing.
     #[cfg_attr(
diff --git a/src/bootstrap/src/core/config/flags.rs b/src/bootstrap/src/core/config/flags.rs
index 56c2541161cec..da479251c68ab 100644
--- a/src/bootstrap/src/core/config/flags.rs
+++ b/src/bootstrap/src/core/config/flags.rs
@@ -10,7 +10,6 @@ use clap_complete::Generator;
 #[cfg(feature = "tracing")]
 use tracing::instrument;
 
-use crate::Build;
 use crate::core::backend::CodegenBackendKind;
 use crate::core::build_steps::perf::PerfArgs;
 use crate::core::build_steps::setup::Profile;
@@ -18,6 +17,7 @@ use crate::core::build_steps::test::TestTarget;
 use crate::core::builder::{Builder, Kind};
 use crate::core::config::Config;
 use crate::core::config::target_selection::{TargetSelectionList, target_selection_list};
+use crate::core::session::Build;
 use crate::utils::helpers;
 
 #[derive(Copy, Clone, Default, Debug, ValueEnum)]
diff --git a/src/bootstrap/src/core/metadata.rs b/src/bootstrap/src/core/metadata.rs
index a3b52e1071d24..5e88277008971 100644
--- a/src/bootstrap/src/core/metadata.rs
+++ b/src/bootstrap/src/core/metadata.rs
@@ -11,7 +11,7 @@ use std::path::PathBuf;
 
 use serde_derive::Deserialize;
 
-use crate::Build;
+use crate::core::session::Build;
 use crate::utils::exec::command;
 use crate::utils::helpers::t;
 
diff --git a/src/bootstrap/src/core/mod.rs b/src/bootstrap/src/core/mod.rs
index d6db6c701cc35..c130051a8c7c4 100644
--- a/src/bootstrap/src/core/mod.rs
+++ b/src/bootstrap/src/core/mod.rs
@@ -8,3 +8,4 @@ pub(crate) mod debuggers;
 pub(crate) mod download;
 pub(crate) mod metadata;
 pub(crate) mod sanity;
+pub(crate) mod session;
diff --git a/src/bootstrap/src/core/sanity.rs b/src/bootstrap/src/core/sanity.rs
index a8359ad34fa50..456019fc96977 100644
--- a/src/bootstrap/src/core/sanity.rs
+++ b/src/bootstrap/src/core/sanity.rs
@@ -14,11 +14,11 @@ use std::ffi::{OsStr, OsString};
 use std::path::PathBuf;
 use std::{env, fs};
 
-use crate::Build;
 use crate::core::build_steps::tool;
 use crate::core::builder::Builder;
 use crate::core::config::flags::Subcommand;
 use crate::core::config::{CompilerBuiltins, DebuggerPath, Target};
+use crate::core::session::Build;
 use crate::utils::exec::command;
 use crate::utils::helpers::{self, t};
 
diff --git a/src/bootstrap/src/core/session.rs b/src/bootstrap/src/core/session.rs
new file mode 100644
index 0000000000000..3e6668258c641
--- /dev/null
+++ b/src/bootstrap/src/core/session.rs
@@ -0,0 +1,1878 @@
+use std::cell::Cell;
+use std::collections::{BTreeSet, HashMap, HashSet};
+use std::fmt::Display;
+use std::path::{Path, PathBuf};
+use std::sync::OnceLock;
+use std::time::{Instant, SystemTime};
+use std::{env, fs, io, str};
+
+use build_helper::ci::gha;
+use termcolor::{ColorChoice, StandardStream, WriteColor};
+#[cfg(feature = "tracing")]
+use tracing::{instrument, span};
+
+use crate::core::build_steps::format::InternalRustfmt;
+use crate::core::build_steps::test::TestTarget;
+use crate::core::build_steps::vendor::VENDOR_DIR;
+use crate::core::builder::{Builder, Kind};
+use crate::core::compiler::Compiler;
+use crate::core::config::flags::{self, Subcommand};
+use crate::core::config::{BootstrapOverrideLld, Config, DryRun, LlvmLibunwind, TargetSelection};
+use crate::core::metadata::Crate;
+#[cfg(feature = "tracing")]
+use crate::trace_io;
+use crate::utils::build_stamp::BuildStamp;
+use crate::utils::channel::GitInfo;
+use crate::utils::exec::{BootstrapCommand, ExecutionContext, command};
+use crate::utils::helpers::{
+    self, dir_is_empty, exe, libdir, set_file_times, split_debuginfo, symlink_dir, t,
+};
+use crate::{debug, trace};
+
+pub(crate) enum GitRepo {
+    Rustc,
+    Llvm,
+}
+
+/// Global configuration for the build system.
+///
+/// This structure transitively contains all configuration for the build system.
+/// All filesystem-encoded configuration is in `config`, all flags are in
+/// `flags`, and then parsed or probed information is listed in the keys below.
+///
+/// This structure is a parameter of almost all methods in the build system,
+/// although most functions are implemented as free functions rather than
+/// methods specifically on this structure itself (to make it easier to
+/// organize).
+pub(crate) struct Build {
+    /// User-specified configuration from `bootstrap.toml`.
+    pub(crate) config: Config,
+
+    // Version information
+    pub(crate) version: String,
+
+    // Properties derived from the above configuration
+    pub(crate) src: PathBuf,
+    pub(crate) out: PathBuf,
+    pub(crate) bootstrap_out: PathBuf,
+    pub(crate) cargo_info: GitInfo,
+    pub(crate) rust_analyzer_info: GitInfo,
+    pub(crate) clippy_info: GitInfo,
+    pub(crate) miri_info: GitInfo,
+    pub(crate) rustfmt_info: GitInfo,
+    pub(crate) enzyme_info: GitInfo,
+    pub(crate) in_tree_llvm_info: GitInfo,
+    pub(crate) in_tree_gcc_info: GitInfo,
+    pub(crate) local_rebuild: bool,
+    pub(crate) fail_fast: bool,
+    pub(crate) test_target: TestTarget,
+    pub(crate) verbosity: usize,
+
+    /// Build triple for the pre-compiled snapshot compiler.
+    pub(crate) host_target: TargetSelection,
+    /// Which triples to produce a compiler toolchain for.
+    pub(crate) hosts: Vec<TargetSelection>,
+    /// Which triples to build libraries (core/alloc/std/test/proc_macro) for.
+    pub(crate) targets: Vec<TargetSelection>,
+
+    pub(crate) initial_rustc: PathBuf,
+    pub(crate) initial_rustdoc: PathBuf,
+    pub(crate) initial_cargo: PathBuf,
+    pub(crate) initial_lld: PathBuf,
+    pub(crate) initial_relative_libdir: PathBuf,
+    pub(crate) initial_sysroot: PathBuf,
+
+    // Runtime state filled in later on
+    // C/C++ compilers and archiver for all targets
+    pub(crate) cc: HashMap<TargetSelection, cc::Tool>,
+    pub(crate) cxx: HashMap<TargetSelection, cc::Tool>,
+    pub(crate) ar: HashMap<TargetSelection, PathBuf>,
+    pub(crate) ranlib: HashMap<TargetSelection, PathBuf>,
+    pub(crate) wasi_sdk_path: Option<PathBuf>,
+
+    // Miscellaneous
+    // allow bidirectional lookups: both name -> path and path -> name
+    pub(crate) crates: HashMap<String, Crate>,
+    pub(crate) crate_paths: HashMap<PathBuf, String>,
+    pub(crate) is_sudo: bool,
+    pub(crate) prerelease_version: Cell<Option<u32>>,
+
+    #[cfg(feature = "build-metrics")]
+    pub(crate) metrics: crate::utils::metrics::BuildMetrics,
+
+    #[cfg(feature = "tracing")]
+    pub(crate) step_graph: std::cell::RefCell<crate::utils::step_graph::StepGraph>,
+}
+
+/// When building Rust various objects are handled differently.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub(crate) enum DependencyType {
+    /// Libraries originating from proc-macros.
+    Host,
+    /// Typical Rust libraries.
+    Target,
+    /// Non Rust libraries and objects shipped to ease usage of certain targets.
+    TargetSelfContained,
+}
+
+/// The various "modes" of invoking Cargo.
+///
+/// These entries currently correspond to the various output directories of the
+/// build system, with each mod generating output in a different directory.
+#[derive(Debug, Hash, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum Mode {
+    /// Build the standard library, placing output in the "stageN-std" directory.
+    Std,
+
+    /// Build librustc, and compiler libraries, placing output in the "stageN-rustc" directory.
+    Rustc,
+
+    /// Build a codegen backend for rustc, placing the output in the "stageN-codegen" directory.
+    Codegen,
+
+    /// Build a tool, placing output in the "bootstrap-tools"
+    /// directory. This is for miscellaneous sets of tools that extend
+    /// bootstrap.
+    ///
+    /// These tools are intended to be only executed on the host system that
+    /// invokes bootstrap, and they thus cannot be cross-compiled.
+    ///
+    /// They are always built using the stage0 compiler, and they
+    /// can be compiled with stable Rust.
+    ///
+    /// These tools also essentially do not participate in staging.
+    ToolBootstrap,
+
+    /// Build a cross-compilable helper tool. These tools do not depend on unstable features or
+    /// compiler internals, but they might be cross-compilable (so we cannot build them using the
+    /// stage0 compiler, unlike `ToolBootstrap`).
+    ///
+    /// Some of these tools are also shipped in our `dist` archives.
+    /// While we could compile them using the stage0 compiler when not cross-compiling, we instead
+    /// use the in-tree compiler (and std) to build them, so that we can ship e.g. std security
+    /// fixes and avoid depending fully on stage0 for the artifacts that we ship.
+    ///
+    /// This mode is used e.g. for linkers and linker tools invoked by rustc on its host target.
+    ToolTarget,
+
+    /// Build a tool which uses the locally built std, placing output in the
+    /// "stageN-tools" directory. Its usage is quite rare; historically it was
+    /// needed by compiletest, but now it is mainly used by `test-float-parse`.
+    ToolStd,
+
+    /// Build a tool which uses the `rustc_private` mechanism, and thus
+    /// the locally built rustc rlib artifacts,
+    /// placing the output in the "stageN-tools" directory. This is used for
+    /// everything that links to rustc as a library, such as rustdoc, clippy,
+    /// rustfmt, miri, etc.
+    ToolRustcPrivate,
+}
+
+impl Mode {
+    pub(crate) fn must_support_dlopen(&self) -> bool {
+        match self {
+            Mode::Std | Mode::Codegen => true,
+            Mode::ToolBootstrap
+            | Mode::ToolRustcPrivate
+            | Mode::ToolStd
+            | Mode::ToolTarget
+            | Mode::Rustc => false,
+        }
+    }
+}
+
+/// When `rust.rust_remap_debuginfo` is requested, the compiler needs to know how to
+/// opportunistically unremap compiler vs non-compiler sources. We use two schemes,
+/// [`RemapScheme::Compiler`] and [`RemapScheme::NonCompiler`].
+pub(crate) enum RemapScheme {
+    /// The [`RemapScheme::Compiler`] scheme will remap to `/rustc-dev/{hash}`.
+    Compiler,
+    /// The [`RemapScheme::NonCompiler`] scheme will remap to `/rustc/{hash}`.
+    NonCompiler,
+}
+
+#[derive(Debug, Hash, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum CLang {
+    C,
+    Cxx,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum FileType {
+    /// An executable binary file (like a `.exe`).
+    Executable,
+    /// A native, binary library file (like a `.so`, `.dll`, `.a`, `.lib` or `.o`).
+    NativeLibrary,
+    /// An executable (non-binary) script file (like a `.py` or `.sh`).
+    Script,
+    /// Any other regular file that is non-executable.
+    Regular,
+}
+
+impl FileType {
+    /// Get Unix permissions appropriate for this file type.
+    pub(crate) fn perms(self) -> u32 {
+        match self {
+            FileType::Executable | FileType::Script => 0o755,
+            FileType::Regular | FileType::NativeLibrary => 0o644,
+        }
+    }
+
+    pub(crate) fn could_have_split_debuginfo(self) -> bool {
+        match self {
+            FileType::Executable | FileType::NativeLibrary => true,
+            FileType::Script | FileType::Regular => false,
+        }
+    }
+}
+
+macro_rules! forward {
+    ( $( $fn:ident( $($param:ident: $ty:ty),* ) $( -> $ret:ty)? ),+ $(,)? ) => {
+        impl Build {
+            $(
+                pub(crate) fn $fn(&self, $($param: $ty),* ) $( -> $ret)? {
+                    self.config.$fn( $($param),* )
+                }
+            )+
+        }
+    }
+}
+
+forward! {
+    do_if_verbose(f: impl Fn()),
+    is_verbose() -> bool,
+    create(path: &Path, s: &str),
+    remove(f: &Path),
+    tempdir() -> PathBuf,
+    download_rustc() -> bool,
+}
+
+/// An alternative way of specifying what target and stage is involved in some bootstrap activity.
+/// Ideally using a `Compiler` directly should be preferred.
+pub(crate) struct TargetAndStage {
+    target: TargetSelection,
+    stage: u32,
+}
+
+impl From<(TargetSelection, u32)> for TargetAndStage {
+    fn from((target, stage): (TargetSelection, u32)) -> Self {
+        Self { target, stage }
+    }
+}
+
+impl From<Compiler> for TargetAndStage {
+    fn from(compiler: Compiler) -> Self {
+        Self { target: compiler.host, stage: compiler.stage }
+    }
+}
+
+impl Build {
+    /// Creates a new set of build configuration from the `flags` on the command
+    /// line and the filesystem `config`.
+    ///
+    /// By default all build output will be placed in the current directory.
+    pub(crate) fn new(mut config: Config) -> Build {
+        let src = config.src.clone();
+        let out = config.out.clone();
+
+        #[cfg(unix)]
+        // keep this consistent with the equivalent check in x.py:
+        // https://github.com/rust-lang/rust/blob/a8a33cf27166d3eabaffc58ed3799e054af3b0c6/src/bootstrap/bootstrap.py#L796-L797
+        let is_sudo = match env::var_os("SUDO_USER") {
+            Some(_sudo_user) => {
+                // SAFETY: getuid() system call is always successful and no return value is reserved
+                // to indicate an error.
+                //
+                // For more context, see https://man7.org/linux/man-pages/man2/geteuid.2.html
+                let uid = unsafe { libc::getuid() };
+                uid == 0
+            }
+            None => false,
+        };
+        #[cfg(not(unix))]
+        let is_sudo = false;
+
+        let rust_info = config.rust_info.clone();
+        let cargo_info = config.cargo_info.clone();
+        let rust_analyzer_info = config.rust_analyzer_info.clone();
+        let clippy_info = config.clippy_info.clone();
+        let miri_info = config.miri_info.clone();
+        let rustfmt_info = config.rustfmt_info.clone();
+        let enzyme_info = config.enzyme_info.clone();
+        let in_tree_llvm_info = config.in_tree_llvm_info.clone();
+        let in_tree_gcc_info = config.in_tree_gcc_info.clone();
+
+        let initial_target_libdir = command(&config.initial_rustc)
+            .run_in_dry_run()
+            .args(["--print", "target-libdir"])
+            .run_capture_stdout(&config)
+            .stdout()
+            .trim()
+            .to_owned();
+
+        let initial_target_dir = Path::new(&initial_target_libdir)
+            .parent()
+            .unwrap_or_else(|| panic!("{initial_target_libdir} has no parent"));
+
+        let initial_lld = initial_target_dir.join("bin").join("rust-lld");
+
+        let initial_relative_libdir = if cfg!(test) {
+            // On tests, bootstrap uses the shim rustc, not the one from the stage0 toolchain.
+            PathBuf::default()
+        } else {
+            let ancestor = initial_target_dir.ancestors().nth(2).unwrap_or_else(|| {
+                panic!("Not enough ancestors for {}", initial_target_dir.display())
+            });
+
+            ancestor
+                .strip_prefix(&config.initial_sysroot)
+                .unwrap_or_else(|_| {
+                    panic!(
+                        "Couldn’t resolve the initial relative libdir from {}",
+                        initial_target_dir.display()
+                    )
+                })
+                .to_path_buf()
+        };
+
+        let version = std::fs::read_to_string(src.join("src").join("version"))
+            .expect("failed to read src/version");
+        let version = version.trim();
+
+        let mut bootstrap_out = std::env::current_exe()
+            .expect("could not determine path to running process")
+            .parent()
+            .unwrap()
+            .to_path_buf();
+        // Since bootstrap is hardlink to deps/bootstrap-*, Solaris can sometimes give
+        // path with deps/ which is bad and needs to be avoided.
+        if bootstrap_out.ends_with("deps") {
+            bootstrap_out.pop();
+        }
+        if !bootstrap_out.join(exe("rustc", config.host_target)).exists() && !cfg!(test) {
+            // this restriction can be lifted whenever https://github.com/rust-lang/rfcs/pull/3028 is implemented
+            panic!(
+                "`rustc` not found in {}, run `cargo build --bins` before `cargo run`",
+                bootstrap_out.display()
+            )
+        }
+
+        if rust_info.is_from_tarball() && config.description.is_none() {
+            config.description = Some("built from a source tarball".to_owned());
+        }
+
+        let mut build = Build {
+            initial_lld,
+            initial_relative_libdir,
+            initial_rustc: config.initial_rustc.clone(),
+            initial_rustdoc: config.initial_rustdoc.clone(),
+            initial_cargo: config.initial_cargo.clone(),
+            initial_sysroot: config.initial_sysroot.clone(),
+            local_rebuild: config.local_rebuild,
+            fail_fast: config.cmd.fail_fast(),
+            test_target: config.cmd.test_target(),
+            verbosity: config.exec_ctx.verbosity as usize,
+
+            host_target: config.host_target,
+            hosts: config.hosts.clone(),
+            targets: config.targets.clone(),
+
+            config,
+            version: version.to_string(),
+            src,
+            out,
+            bootstrap_out,
+
+            cargo_info,
+            rust_analyzer_info,
+            clippy_info,
+            miri_info,
+            rustfmt_info,
+            enzyme_info,
+            in_tree_llvm_info,
+            in_tree_gcc_info,
+            cc: HashMap::new(),
+            cxx: HashMap::new(),
+            ar: HashMap::new(),
+            ranlib: HashMap::new(),
+            wasi_sdk_path: env::var_os("WASI_SDK_PATH").map(PathBuf::from),
+            crates: HashMap::new(),
+            crate_paths: HashMap::new(),
+            is_sudo,
+            prerelease_version: Cell::new(None),
+
+            #[cfg(feature = "build-metrics")]
+            metrics: crate::utils::metrics::BuildMetrics::init(),
+
+            #[cfg(feature = "tracing")]
+            step_graph: std::cell::RefCell::new(crate::utils::step_graph::StepGraph::default()),
+        };
+
+        // If local-rust is the same major.minor as the current version, then force a
+        // local-rebuild
+        let local_version_verbose = command(&build.initial_rustc)
+            .run_in_dry_run()
+            .args(["--version", "--verbose"])
+            .run_capture_stdout(&build)
+            .stdout();
+        let local_release = local_version_verbose
+            .lines()
+            .filter_map(|x| x.strip_prefix("release:"))
+            .next()
+            .unwrap()
+            .trim();
+        if local_release.split('.').take(2).eq(version.split('.').take(2)) {
+            build.do_if_verbose(|| println!("auto-detected local-rebuild {local_release}"));
+            build.local_rebuild = true;
+        }
+
+        build.do_if_verbose(|| println!("finding compilers"));
+        crate::utils::cc_detect::fill_compilers(&mut build);
+        // When running `setup`, the profile is about to change, so any requirements we have now may
+        // be different on the next invocation. Don't check for them until the next time x.py is
+        // run. This is ok because `setup` never runs any build commands, so it won't fail if commands are missing.
+        //
+        // Similarly, for `setup` we don't actually need submodules or cargo metadata.
+        if !matches!(build.config.cmd, Subcommand::Setup { .. }) {
+            build.do_if_verbose(|| println!("running sanity check"));
+            crate::core::sanity::check(&mut build);
+
+            // Make sure we update these before gathering metadata so we don't get an error about missing
+            // Cargo.toml files.
+            let rust_submodules = ["library/backtrace"];
+            for s in rust_submodules {
+                build.require_submodule(
+                    s,
+                    Some(
+                        "The submodule is required for the standard library \
+                         and the main Cargo workspace.",
+                    ),
+                );
+            }
+            // Now, update all existing submodules.
+            build.update_existing_submodules();
+
+            build.do_if_verbose(|| println!("learning about cargo"));
+            crate::core::metadata::build(&mut build);
+        }
+
+        // Create symbolic link to use host sysroot from a consistent path (e.g., in the rust-analyzer config file).
+        let build_triple = build.out.join(build.host_target);
+        t!(fs::create_dir_all(&build_triple));
+        let host = build.out.join("host");
+        if host.is_symlink() {
+            // Left over from a previous build; overwrite it.
+            // This matters if `build.build` has changed between invocations.
+            #[cfg(windows)]
+            t!(fs::remove_dir(&host));
+            #[cfg(not(windows))]
+            t!(fs::remove_file(&host));
+        }
+        t!(
+            symlink_dir(&build.config, &build_triple, &host),
+            format!("symlink_dir({} => {}) failed", host.display(), build_triple.display())
+        );
+
+        build
+    }
+
+    /// Updates a submodule, and exits with a failure if submodule management
+    /// is disabled and the submodule does not exist.
+    ///
+    /// The given submodule name should be its path relative to the root of
+    /// the main repository.
+    ///
+    /// The given `err_hint` will be shown to the user if the submodule is not
+    /// checked out and submodule management is disabled.
+    #[cfg_attr(
+        feature = "tracing",
+        instrument(
+            level = "trace",
+            name = "Build::require_submodule",
+            skip_all,
+            fields(submodule = submodule),
+        ),
+    )]
+    pub(crate) fn require_submodule(&self, submodule: &str, err_hint: Option<&str>) {
+        if self.rust_info().is_from_tarball() {
+            return;
+        }
+
+        if self.config.dry_run() {
+            return;
+        }
+
+        // When testing bootstrap itself, it is much faster to ignore
+        // submodules. Almost all Steps work fine without their submodules.
+        if cfg!(test) && !self.config.submodules() {
+            return;
+        }
+        self.config.update_submodule(submodule);
+        let absolute_path = self.config.src.join(submodule);
+        if !absolute_path.exists() || dir_is_empty(&absolute_path) {
+            let maybe_enable = if !self.config.submodules()
+                && self.config.rust_info.is_managed_git_subrepository()
+            {
+                "\nConsider setting `build.submodules = true` or manually initializing the submodules."
+            } else {
+                ""
+            };
+            let err_hint = err_hint.map_or_else(String::new, |e| format!("\n{e}"));
+            eprintln!(
+                "submodule {submodule} does not appear to be checked out, \
+                 but it is required for this step{maybe_enable}{err_hint}"
+            );
+            helpers::exit_process(1);
+        }
+    }
+
+    /// If any submodule has been initialized already, sync it unconditionally.
+    /// This avoids contributors checking in a submodule change by accident.
+    pub(crate) fn update_existing_submodules(&self) {
+        // Avoid running git when there isn't a git checkout, or the user has
+        // explicitly disabled submodules in `bootstrap.toml`.
+        if !self.config.submodules() {
+            return;
+        }
+        let output = helpers::git(Some(&self.src))
+            .args(["config", "--file"])
+            .arg(".gitmodules")
+            .args(["--get-regexp", "path"])
+            .run_capture(self)
+            .stdout();
+        std::thread::scope(|s| {
+            // Look for `submodule.$name.path = $path`
+            // Sample output: `submodule.src/rust-installer.path src/tools/rust-installer`
+            for line in output.lines() {
+                let submodule = line.split_once(' ').unwrap().1;
+                let config = self.config.clone();
+                s.spawn(move || {
+                    Self::update_existing_submodule(&config, submodule);
+                });
+            }
+        });
+    }
+
+    /// Updates the given submodule only if it's initialized already; nothing happens otherwise.
+    pub(crate) fn update_existing_submodule(config: &Config, submodule: &str) {
+        // Avoid running git when there isn't a git checkout.
+        if !config.submodules() {
+            return;
+        }
+
+        if config.git_info(false, Path::new(submodule)).is_managed_git_subrepository() {
+            config.update_submodule(submodule);
+        }
+    }
+
+    /// Executes the entire build, as configured by the flags and configuration.
+    #[cfg_attr(feature = "tracing", instrument(level = "debug", name = "Build::build", skip_all))]
+    pub(crate) fn build(&mut self) {
+        trace!("setting up job management");
+        unsafe {
+            crate::utils::job::setup(self);
+        }
+
+        // Handle hard-coded subcommands.
+        {
+            #[cfg(feature = "tracing")]
+            let _hardcoded_span =
+                span!(tracing::Level::DEBUG, "handling hardcoded subcommands (Format, Perf)")
+                    .entered();
+
+            match &self.config.cmd {
+                Subcommand::Format { check, all } => {
+                    let builder = Builder::new(self);
+                    let rustfmt_path = builder.ensure(InternalRustfmt).unwrap_or_else(|| {
+                        eprintln!("fmt error: `x fmt` is not supported on this channel");
+                        helpers::exit_process(1);
+                    });
+                    return crate::core::build_steps::format::format(
+                        &builder,
+                        rustfmt_path,
+                        *check,
+                        *all,
+                        &self.config.paths,
+                    );
+                }
+                Subcommand::Perf(args) => {
+                    return crate::core::build_steps::perf::perf(&Builder::new(self), args);
+                }
+                _cmd => {
+                    debug!(cmd = ?_cmd, "not a hardcoded subcommand; returning to normal handling");
+                }
+            }
+
+            debug!("handling subcommand normally");
+        }
+
+        if !self.config.dry_run() {
+            #[cfg(feature = "tracing")]
+            let _real_run_span = span!(tracing::Level::DEBUG, "executing real run").entered();
+
+            // We first do a dry-run. This is a sanity-check to ensure that
+            // steps don't do anything expensive in the dry-run.
+            {
+                #[cfg(feature = "tracing")]
+                let _sanity_check_span =
+                    span!(tracing::Level::DEBUG, "(1) executing dry-run sanity-check").entered();
+                self.config.set_dry_run(DryRun::SelfCheck);
+                let builder = Builder::new(self);
+                builder.execute_cli();
+            }
+
+            // Actual run.
+            {
+                #[cfg(feature = "tracing")]
+                let _actual_run_span =
+                    span!(tracing::Level::DEBUG, "(2) executing actual run").entered();
+                self.config.set_dry_run(DryRun::Disabled);
+                let builder = Builder::new(self);
+                builder.execute_cli();
+            }
+        } else {
+            #[cfg(feature = "tracing")]
+            let _dry_run_span = span!(tracing::Level::DEBUG, "executing dry run").entered();
+
+            let builder = Builder::new(self);
+            builder.execute_cli();
+        }
+
+        #[cfg(feature = "tracing")]
+        debug!("checking for postponed test failures from `test  --no-fail-fast`");
+
+        // Check for postponed failures from `test --no-fail-fast`.
+        self.config.exec_ctx().report_failures_and_exit();
+
+        #[cfg(feature = "build-metrics")]
+        self.metrics.persist(self);
+    }
+
+    pub(crate) fn rust_info(&self) -> &GitInfo {
+        &self.config.rust_info
+    }
+
+    /// Gets the space-separated set of activated features for the standard library.
+    /// This can be configured with the `std-features` key in bootstrap.toml.
+    pub(crate) fn std_features(&self, target: TargetSelection) -> String {
+        let mut features: BTreeSet<&str> =
+            self.config.rust_std_features.iter().map(|s| s.as_str()).collect();
+
+        match self.config.llvm_libunwind(target) {
+            LlvmLibunwind::InTree => features.insert("llvm-libunwind"),
+            LlvmLibunwind::System => features.insert("system-llvm-libunwind"),
+            LlvmLibunwind::No => false,
+        };
+
+        if self.config.backtrace {
+            features.insert("backtrace");
+        }
+
+        if self.config.profiler_enabled(target) {
+            features.insert("profiler");
+        }
+
+        // If zkvm target, generate memcpy, etc.
+        if target.contains("zkvm") {
+            features.insert("compiler-builtins-mem");
+        }
+
+        features.into_iter().collect::<Vec<_>>().join(" ")
+    }
+
+    /// Gets the space-separated set of activated features for the compiler.
+    pub(crate) fn rustc_features(
+        &self,
+        kind: Kind,
+        target: TargetSelection,
+        crates: &[String],
+    ) -> String {
+        let possible_features_by_crates: HashSet<_> = crates
+            .iter()
+            .flat_map(|krate| &self.crates[krate].features)
+            .map(std::ops::Deref::deref)
+            .collect();
+        let check = |feature: &str| -> bool {
+            crates.is_empty() || possible_features_by_crates.contains(feature)
+        };
+        let mut features = vec![];
+
+        if let Some(allocator_feature_name) = self.config.allocator(target).feature_name()
+            && check(allocator_feature_name)
+        {
+            features.push(allocator_feature_name);
+        }
+        if (self.config.llvm_enabled(target) || kind == Kind::Check) && check("llvm") {
+            features.push("llvm");
+        }
+        if self.config.llvm_offload {
+            features.push("llvm_offload");
+        }
+        // keep in sync with `bootstrap/compile.rs:rustc_cargo_env`
+        if self.config.rust_randomize_layout && check("rustc_randomized_layouts") {
+            features.push("rustc_randomized_layouts");
+        }
+        if self.config.compile_time_deps && kind == Kind::Check {
+            features.push("check_only");
+        }
+
+        if crates.iter().any(|c| c == "rustc_transmute") {
+            // for `x test rustc_transmute`, this feature isn't enabled automatically by a
+            // dependent crate.
+            features.push("rustc");
+        }
+
+        // If debug logging is on, then we want the default for tracing:
+        // https://github.com/tokio-rs/tracing/blob/3dd5c03d907afdf2c39444a29931833335171554/tracing/src/level_filters.rs#L26
+        // which is everything (including debug/trace/etc.)
+        // if its unset, if debug_assertions is on, then debug_logging will also be on
+        // as well as tracing *ignoring* this feature when debug_assertions is on
+        if !self.config.rust_debug_logging && check("max_level_info") {
+            features.push("max_level_info");
+        }
+
+        features.join(" ")
+    }
+
+    /// Component directory that Cargo will produce output into (e.g.
+    /// release/debug)
+    pub(crate) fn cargo_dir(&self, mode: Mode) -> &'static str {
+        match (mode, self.config.rust_optimize.is_release()) {
+            (Mode::Std, _) => "dist",
+            (_, true) => "release",
+            (_, false) => "debug",
+        }
+    }
+
+    pub(crate) fn tools_dir(&self, build_compiler: Compiler) -> PathBuf {
+        let out = self
+            .out
+            .join(build_compiler.host)
+            .join(format!("stage{}-tools-bin", build_compiler.stage + 1));
+        t!(fs::create_dir_all(&out));
+        out
+    }
+
+    /// Returns the root directory for all output generated in a particular
+    /// stage when being built with a particular build compiler.
+    ///
+    /// The mode indicates what the root directory is for.
+    pub(crate) fn stage_out(&self, build_compiler: Compiler, mode: Mode) -> PathBuf {
+        use std::fmt::Write;
+
+        fn bootstrap_tool() -> (Option<u32>, &'static str) {
+            (None, "bootstrap-tools")
+        }
+        fn staged_tool(build_compiler: Compiler) -> (Option<u32>, &'static str) {
+            (Some(build_compiler.stage + 1), "tools")
+        }
+
+        let (stage, suffix) = match mode {
+            // Std is special, stage N std is built with stage N rustc
+            Mode::Std => (Some(build_compiler.stage), "std"),
+            // The rest of things are built with stage N-1 rustc
+            Mode::Rustc => (Some(build_compiler.stage + 1), "rustc"),
+            Mode::Codegen => (Some(build_compiler.stage + 1), "codegen"),
+            Mode::ToolBootstrap => bootstrap_tool(),
+            Mode::ToolStd | Mode::ToolRustcPrivate => (Some(build_compiler.stage + 1), "tools"),
+            Mode::ToolTarget => {
+                // If we're not cross-compiling (the common case), share the target directory with
+                // bootstrap tools to reuse the build cache.
+                if build_compiler.stage == 0 {
+                    bootstrap_tool()
+                } else {
+                    staged_tool(build_compiler)
+                }
+            }
+        };
+        let path = self.out.join(build_compiler.host);
+        let mut dir_name = String::new();
+        if let Some(stage) = stage {
+            write!(dir_name, "stage{stage}-").unwrap();
+        }
+        dir_name.push_str(suffix);
+        path.join(dir_name)
+    }
+
+    /// Returns the root output directory for all Cargo output in a given stage,
+    /// running a particular compiler, whether or not we're building the
+    /// standard library, and targeting the specified architecture.
+    pub(crate) fn cargo_out(
+        &self,
+        build_compiler: Compiler,
+        mode: Mode,
+        target: TargetSelection,
+    ) -> PathBuf {
+        self.stage_out(build_compiler, mode).join(target).join(self.cargo_dir(mode))
+    }
+
+    /// Output directory for all documentation for a target
+    pub(crate) fn doc_out(&self, target: TargetSelection) -> PathBuf {
+        self.out.join(target).join("doc")
+    }
+
+    /// Output directory for all JSON-formatted documentation for a target
+    pub(crate) fn json_doc_out(&self, target: TargetSelection) -> PathBuf {
+        self.out.join(target).join("json-doc")
+    }
+
+    pub(crate) fn test_out(&self, target: TargetSelection) -> PathBuf {
+        self.out.join(target).join("test")
+    }
+
+    /// Output directory for all documentation for a target
+    pub(crate) fn compiler_doc_out(&self, target: TargetSelection) -> PathBuf {
+        self.out.join(target).join("compiler-doc")
+    }
+
+    /// Output directory for some generated md crate documentation for a target (temporary)
+    pub(crate) fn md_doc_out(&self, target: TargetSelection) -> PathBuf {
+        self.out.join(target).join("md-doc")
+    }
+
+    /// Path to the vendored Rust crates.
+    pub(crate) fn vendored_crates_path(&self) -> Option<PathBuf> {
+        if self.config.vendor { Some(self.src.join(VENDOR_DIR)) } else { None }
+    }
+
+    /// Directory for libraries built from C/C++ code and shared between stages.
+    pub(crate) fn native_dir(&self, target: TargetSelection) -> PathBuf {
+        self.out.join(target).join("native")
+    }
+
+    /// Root output directory for rust_test_helpers library compiled for
+    /// `target`
+    pub(crate) fn test_helpers_out(&self, target: TargetSelection) -> PathBuf {
+        self.native_dir(target).join("rust-test-helpers")
+    }
+
+    /// Adds the `RUST_TEST_THREADS` env var if necessary
+    pub(crate) fn add_rust_test_threads(&self, cmd: &mut BootstrapCommand) {
+        if env::var_os("RUST_TEST_THREADS").is_none() {
+            cmd.env("RUST_TEST_THREADS", self.jobs().to_string());
+        }
+    }
+
+    /// Returns the libdir of the snapshot compiler.
+    pub(crate) fn rustc_snapshot_libdir(&self) -> PathBuf {
+        self.rustc_snapshot_sysroot().join(libdir(self.config.host_target))
+    }
+
+    /// Returns the sysroot of the snapshot compiler.
+    pub(crate) fn rustc_snapshot_sysroot(&self) -> &Path {
+        static SYSROOT_CACHE: OnceLock<PathBuf> = OnceLock::new();
+        SYSROOT_CACHE.get_or_init(|| {
+            command(&self.initial_rustc)
+                .run_in_dry_run()
+                .args(["--print", "sysroot"])
+                .run_capture_stdout(self)
+                .stdout()
+                .trim()
+                .to_owned()
+                .into()
+        })
+    }
+
+    pub(crate) fn info(&self, msg: &str) {
+        match self.config.get_dry_run() {
+            DryRun::SelfCheck => (),
+            DryRun::Disabled | DryRun::UserSelected => {
+                println!("{msg}");
+            }
+        }
+    }
+
+    /// Return a `Group` guard for a [`Step`] that:
+    /// - Performs `action`
+    ///   - If the action is `Kind::Test`, use [`Build::msg_test`] instead.
+    /// - On `what`
+    ///   - Where `what` possibly corresponds to a `mode`
+    /// - `action` is performed with/on the given compiler (`target_and_stage`).
+    ///   - Since for some steps it is not possible to pass a single compiler here, it is also
+    ///     possible to pass the host and stage explicitly.
+    /// - With a given `target`.
+    ///
+    /// [`Step`]: crate::core::builder::Step
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
+    #[track_caller]
+    pub(crate) fn msg(
+        &self,
+        action: impl Into<Kind>,
+        what: impl Display,
+        mode: impl Into<Option<Mode>>,
+        target_and_stage: impl Into<TargetAndStage>,
+        target: impl Into<Option<TargetSelection>>,
+    ) -> Option<gha::Group> {
+        let target_and_stage = target_and_stage.into();
+        let action = action.into();
+        assert!(
+            action != Kind::Test,
+            "Please use `Build::msg_test` instead of `Build::msg(Kind::Test)`"
+        );
+
+        let actual_stage = match mode.into() {
+            // Std has the same stage as the compiler that builds it
+            Some(Mode::Std) => target_and_stage.stage,
+            // Other things have stage corresponding to their build compiler + 1
+            Some(
+                Mode::Rustc
+                | Mode::Codegen
+                | Mode::ToolBootstrap
+                | Mode::ToolTarget
+                | Mode::ToolStd
+                | Mode::ToolRustcPrivate,
+            )
+            | None => target_and_stage.stage + 1,
+        };
+
+        let action = action.description();
+        let what = what.to_string();
+        let msg = |fmt| {
+            let space = if !what.is_empty() { " " } else { "" };
+            format!("{action} stage{actual_stage} {what}{space}{fmt}")
+        };
+        let msg = if let Some(target) = target.into() {
+            let build_stage = target_and_stage.stage;
+            let host = target_and_stage.target;
+            if host == target {
+                msg(format_args!("(stage{build_stage} -> stage{actual_stage}, {target})"))
+            } else {
+                msg(format_args!("(stage{build_stage}:{host} -> stage{actual_stage}:{target})"))
+            }
+        } else {
+            msg(format_args!(""))
+        };
+        self.group(&msg)
+    }
+
+    /// Return a `Group` guard for a [`Step`] that tests `what` with the given `stage` and `target`.
+    /// Use this instead of [`Build::msg`] for test steps, because for them it is not always clear
+    /// what exactly is a build compiler.
+    ///
+    /// [`Step`]: crate::core::builder::Step
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
+    #[track_caller]
+    pub(crate) fn msg_test(
+        &self,
+        what: impl Display,
+        target: TargetSelection,
+        stage: u32,
+    ) -> Option<gha::Group> {
+        let action = Kind::Test.description();
+        let msg = format!("{action} stage{stage} {what} ({target})");
+        self.group(&msg)
+    }
+
+    /// Return a `Group` guard for a [`Step`] that is only built once and isn't affected by `--stage`.
+    ///
+    /// [`Step`]: crate::core::builder::Step
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
+    #[track_caller]
+    pub(crate) fn msg_unstaged(
+        &self,
+        action: impl Into<Kind>,
+        what: impl Display,
+        target: TargetSelection,
+    ) -> Option<gha::Group> {
+        let action = action.into().description();
+        let msg = format!("{action} {what} for {target}");
+        self.group(&msg)
+    }
+
+    #[track_caller]
+    pub(crate) fn group(&self, msg: &str) -> Option<gha::Group> {
+        match self.config.get_dry_run() {
+            DryRun::SelfCheck => None,
+            DryRun::Disabled | DryRun::UserSelected => Some(gha::group(msg)),
+        }
+    }
+
+    /// Returns the number of parallel jobs that have been configured for this
+    /// build.
+    pub(crate) fn jobs(&self) -> u32 {
+        self.config.jobs.unwrap_or_else(|| {
+            std::thread::available_parallelism().map_or(1, std::num::NonZeroUsize::get) as u32
+        })
+    }
+
+    pub(crate) fn debuginfo_map_to(
+        &self,
+        which: GitRepo,
+        remap_scheme: RemapScheme,
+    ) -> Option<String> {
+        if !self.config.rust_remap_debuginfo {
+            return None;
+        }
+
+        match which {
+            GitRepo::Rustc => {
+                let sha = self.rust_sha().unwrap_or(&self.version);
+
+                match remap_scheme {
+                    RemapScheme::Compiler => {
+                        // For compiler sources, remap via `/rustc-dev/{sha}` to allow
+                        // distinguishing between compiler sources vs library sources, since
+                        // `rustc-dev` dist component places them under
+                        // `$sysroot/lib/rustlib/rustc-src/rust` as opposed to `rust-src`'s
+                        // `$sysroot/lib/rustlib/src/rust`.
+                        //
+                        // Keep this scheme in sync with `rustc_metadata::rmeta::decoder`'s
+                        // `try_to_translate_virtual_to_real`.
+                        Some(format!("/rustc-dev/{sha}"))
+                    }
+                    RemapScheme::NonCompiler => {
+                        // For non-compiler sources, use `/rustc/{sha}` remapping scheme.
+                        Some(format!("/rustc/{sha}"))
+                    }
+                }
+            }
+            GitRepo::Llvm => Some(String::from("/rustc/llvm")),
+        }
+    }
+
+    /// Returns the path to the C compiler for the target specified.
+    pub(crate) fn cc(&self, target: TargetSelection) -> PathBuf {
+        if self.config.dry_run() {
+            return PathBuf::new();
+        }
+        self.cc[&target].path().into()
+    }
+
+    /// Returns the internal `cc::Tool` for the C compiler.
+    pub(crate) fn cc_tool(&self, target: TargetSelection) -> cc::Tool {
+        self.cc[&target].clone()
+    }
+
+    /// Returns the internal `cc::Tool` for the C++ compiler.
+    pub(crate) fn cxx_tool(&self, target: TargetSelection) -> cc::Tool {
+        self.cxx[&target].clone()
+    }
+
+    /// Returns C flags that `cc-rs` thinks should be enabled for the
+    /// specified target by default.
+    pub(crate) fn cc_handled_cflags(&self, target: TargetSelection, c: CLang) -> Vec<String> {
+        if self.config.dry_run() {
+            return Vec::new();
+        }
+        let base = match c {
+            CLang::C => self.cc[&target].clone(),
+            CLang::Cxx => self.cxx[&target].clone(),
+        };
+
+        // Filter out -O and /O (the optimization flags) that we picked up
+        // from cc-rs, that's up to the caller to figure out.
+        base.args()
+            .iter()
+            .map(|s| s.to_string_lossy().into_owned())
+            .filter(|s| !s.starts_with("-O") && !s.starts_with("/O"))
+            .collect::<Vec<String>>()
+    }
+
+    /// Returns extra C flags that `cc-rs` doesn't handle.
+    pub(crate) fn cc_unhandled_cflags(
+        &self,
+        target: TargetSelection,
+        which: GitRepo,
+        c: CLang,
+    ) -> Vec<String> {
+        let mut base = Vec::new();
+
+        // If we're compiling C++ on macOS then we add a flag indicating that
+        // we want libc++ (more filled out than libstdc++), ensuring that
+        // LLVM/etc are all properly compiled.
+        if matches!(c, CLang::Cxx) && target.contains("apple-darwin") {
+            base.push("-stdlib=libc++".into());
+        }
+
+        // Work around an apparently bad MinGW / GCC optimization,
+        // See: https://lists.llvm.org/pipermail/cfe-dev/2016-December/051980.html
+        // See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78936
+        if &*target.triple == "i686-pc-windows-gnu" {
+            base.push("-fno-omit-frame-pointer".into());
+        }
+
+        if let Some(map_to) = self.debuginfo_map_to(which, RemapScheme::NonCompiler) {
+            let map = format!("{}={}", self.src.display(), map_to);
+            let cc = self.cc_tool(target);
+            if cc.is_like_clang() || cc.is_like_gnu() {
+                base.push(format!("-fdebug-prefix-map={map}"));
+            } else if cc.is_like_clang_cl() {
+                base.push("-Xclang".into());
+                base.push(format!("-fdebug-prefix-map={map}"));
+            }
+        }
+        base
+    }
+
+    /// Returns the path to the `ar` archive utility for the target specified.
+    pub(crate) fn ar(&self, target: TargetSelection) -> Option<PathBuf> {
+        if self.config.dry_run() {
+            return None;
+        }
+        self.ar.get(&target).cloned()
+    }
+
+    /// Returns the path to the `ranlib` utility for the target specified.
+    pub(crate) fn ranlib(&self, target: TargetSelection) -> Option<PathBuf> {
+        if self.config.dry_run() {
+            return None;
+        }
+        self.ranlib.get(&target).cloned()
+    }
+
+    /// Returns the path to the C++ compiler for the target specified.
+    pub(crate) fn cxx(&self, target: TargetSelection) -> Result<PathBuf, String> {
+        if self.config.dry_run() {
+            return Ok(PathBuf::new());
+        }
+        match self.cxx.get(&target) {
+            Some(p) => Ok(p.path().into()),
+            None => Err(format!("target `{target}` is not configured as a host, only as a target")),
+        }
+    }
+
+    /// Returns the path to the linker for the given target if it needs to be overridden.
+    pub(crate) fn linker(&self, target: TargetSelection) -> Option<PathBuf> {
+        if self.config.dry_run() {
+            return Some(PathBuf::new());
+        }
+        if let Some(linker) = self.config.target_config.get(&target).and_then(|c| c.linker.clone())
+        {
+            Some(linker)
+        } else if target.contains("vxworks") {
+            // need to use CXX compiler as linker to resolve the exception functions
+            // that are only existed in CXX libraries
+            Some(self.cxx[&target].path().into())
+        } else if !self.config.is_host_target(target)
+            && helpers::use_host_linker(target)
+            && !target.is_msvc()
+        {
+            Some(self.cc(target))
+        } else if self.config.bootstrap_override_lld.is_used()
+            && self.is_lld_direct_linker(target)
+            && self.host_target == target
+        {
+            match self.config.bootstrap_override_lld {
+                BootstrapOverrideLld::SelfContained => Some(self.initial_lld.clone()),
+                BootstrapOverrideLld::External => Some("lld".into()),
+                BootstrapOverrideLld::None => None,
+            }
+        } else {
+            None
+        }
+    }
+
+    // Is LLD configured directly through `-Clinker`?
+    // Only MSVC targets use LLD directly at the moment.
+    pub(crate) fn is_lld_direct_linker(&self, target: TargetSelection) -> bool {
+        target.is_msvc()
+    }
+
+    /// Returns if this target should statically link the C runtime, if specified
+    pub(crate) fn crt_static(&self, target: TargetSelection) -> Option<bool> {
+        if target.contains("pc-windows-msvc") {
+            Some(true)
+        } else {
+            self.config.target_config.get(&target).and_then(|t| t.crt_static)
+        }
+    }
+
+    /// Returns the "musl root" for this `target`, if defined.
+    ///
+    /// If this is a native target (host is also musl) and no musl-root is given,
+    /// it falls back to the system toolchain in /usr.
+    pub(crate) fn musl_root(&self, target: TargetSelection) -> Option<&Path> {
+        let configured_root = self
+            .config
+            .target_config
+            .get(&target)
+            .and_then(|t| t.musl_root.as_ref())
+            .or(self.config.musl_root.as_ref())
+            .map(|p| &**p);
+
+        if self.config.is_host_target(target) && configured_root.is_none() {
+            Some(Path::new("/usr"))
+        } else {
+            configured_root
+        }
+    }
+
+    /// Returns the "musl libdir" for this `target`.
+    pub(crate) fn musl_libdir(&self, target: TargetSelection) -> Option<PathBuf> {
+        self.config
+            .target_config
+            .get(&target)
+            .and_then(|t| t.musl_libdir.clone())
+            .or_else(|| self.musl_root(target).map(|root| root.join("lib")))
+    }
+
+    /// Returns the `lib` directory for the WASI target specified, if
+    /// configured.
+    ///
+    /// This first consults `wasi-root` as configured in per-target
+    /// configuration, and failing that it assumes that `$WASI_SDK_PATH` is
+    /// set in the environment, and failing that `None` is returned.
+    pub(crate) fn wasi_libdir(&self, target: TargetSelection) -> Option<PathBuf> {
+        let configured =
+            self.config.target_config.get(&target).and_then(|t| t.wasi_root.as_ref()).map(|p| &**p);
+        if let Some(path) = configured {
+            return Some(path.join("lib").join(target.to_string()));
+        }
+        let mut env_root = self.wasi_sdk_path.clone()?;
+        env_root.push("share");
+        env_root.push("wasi-sysroot");
+        env_root.push("lib");
+        env_root.push(target.to_string());
+        Some(env_root)
+    }
+
+    /// Returns `true` if this is a no-std `target`, if defined
+    pub(crate) fn no_std(&self, target: TargetSelection) -> Option<bool> {
+        self.config.target_config.get(&target).map(|t| t.no_std)
+    }
+
+    /// Returns `true` if the target will be tested using the `remote-test-client`
+    /// and `remote-test-server` binaries.
+    pub(crate) fn remote_tested(&self, target: TargetSelection) -> bool {
+        self.qemu_rootfs(target).is_some()
+            || target.contains("android")
+            || env::var_os("TEST_DEVICE_ADDR").is_some()
+    }
+
+    /// Returns an optional "runner" to pass to `compiletest` when executing
+    /// test binaries.
+    ///
+    /// An example of this would be a WebAssembly runtime when testing the wasm
+    /// targets.
+    pub(crate) fn runner(&self, target: TargetSelection) -> Option<String> {
+        let configured_runner =
+            self.config.target_config.get(&target).and_then(|t| t.runner.as_ref()).map(|p| &**p);
+        if let Some(runner) = configured_runner {
+            return Some(runner.to_owned());
+        }
+
+        if target.starts_with("wasm") && target.contains("wasi") {
+            self.default_wasi_runner(target)
+        } else {
+            None
+        }
+    }
+
+    /// When a `runner` configuration is not provided and a WASI-looking target
+    /// is being tested this is consulted to prove the environment to see if
+    /// there's a runtime already lying around that seems reasonable to use.
+    fn default_wasi_runner(&self, target: TargetSelection) -> Option<String> {
+        let mut finder = crate::core::sanity::Finder::new();
+
+        // Look for Wasmtime, and for its default options be sure to disable
+        // its caching system since we're executing quite a lot of tests and
+        // ideally shouldn't pollute the cache too much.
+        if let Some(path) = finder.maybe_have("wasmtime")
+            && let Ok(mut path) = path.into_os_string().into_string()
+        {
+            path.push_str(" run -Wexceptions -C cache=n --dir .");
+            // Make sure that tests have access to RUSTC_BOOTSTRAP. This (for example) is
+            // required for libtest to work on beta/stable channels.
+            //
+            // NB: with Wasmtime 20 this can change to `-S inherit-env` to
+            // inherit the entire environment rather than just this single
+            // environment variable.
+            path.push_str(" --env RUSTC_BOOTSTRAP");
+
+            if target.contains("wasip2") {
+                path.push_str(" --wasi inherit-network --wasi allow-ip-name-lookup");
+            }
+
+            return Some(path);
+        }
+
+        None
+    }
+
+    /// Returns whether the specified tool is configured as part of this build.
+    ///
+    /// This requires that both the `extended` key is set and the `tools` key is
+    /// either unset or specifically contains the specified tool.
+    pub(crate) fn tool_enabled(&self, tool: &str) -> bool {
+        if !self.config.extended {
+            return false;
+        }
+        match &self.config.tools {
+            Some(set) => set.contains(tool),
+            None => true,
+        }
+    }
+
+    /// Returns the root of the "rootfs" image that this target will be using,
+    /// if one was configured.
+    ///
+    /// If `Some` is returned then that means that tests for this target are
+    /// emulated with QEMU and binaries will need to be shipped to the emulator.
+    pub(crate) fn qemu_rootfs(&self, target: TargetSelection) -> Option<&Path> {
+        self.config.target_config.get(&target).and_then(|t| t.qemu_rootfs.as_ref()).map(|p| &**p)
+    }
+
+    /// Temporary directory that extended error information is emitted to.
+    pub(crate) fn extended_error_dir(&self) -> PathBuf {
+        self.out.join("tmp/extended-error-metadata")
+    }
+
+    /// Tests whether the `compiler` compiling for `target` should be forced to
+    /// use a stage1 compiler instead.
+    ///
+    /// Currently, by default, the build system does not perform a "full
+    /// bootstrap" by default where we compile the compiler three times.
+    /// Instead, we compile the compiler two times. The final stage (stage2)
+    /// just copies the libraries from the previous stage, which is what this
+    /// method detects.
+    ///
+    /// Here we return `true` if:
+    ///
+    /// * The build isn't performing a full bootstrap
+    /// * The `compiler` is in the final stage, 2
+    /// * We're not cross-compiling, so the artifacts are already available in
+    ///   stage1
+    ///
+    /// When all of these conditions are met the build will lift artifacts from
+    /// the previous stage forward.
+    pub(crate) fn force_use_stage1(&self, stage: u32, target: TargetSelection) -> bool {
+        !self.config.full_bootstrap
+            && !self.config.download_rustc()
+            && stage >= 2
+            && (self.hosts.contains(&target) || target == self.host_target)
+    }
+
+    /// Checks whether the `compiler` compiling for `target` should be forced to
+    /// use a stage2 compiler instead.
+    ///
+    /// When we download the pre-compiled version of rustc and compiler stage is >= 2,
+    /// it should be forced to use a stage2 compiler.
+    pub(crate) fn force_use_stage2(&self, stage: u32) -> bool {
+        self.config.download_rustc() && stage >= 2
+    }
+
+    /// Given `num` in the form "a.b.c" return a "release string" which
+    /// describes the release version number.
+    ///
+    /// For example on nightly this returns "a.b.c-nightly", on beta it returns
+    /// "a.b.c-beta.1" and on stable it just returns "a.b.c".
+    pub(crate) fn release(&self, num: &str) -> String {
+        match &self.config.channel[..] {
+            "stable" => num.to_string(),
+            "beta" => {
+                if !self.config.omit_git_hash {
+                    format!("{}-beta.{}", num, self.beta_prerelease_version())
+                } else {
+                    format!("{num}-beta")
+                }
+            }
+            "nightly" => format!("{num}-nightly"),
+            _ => format!("{num}-dev"),
+        }
+    }
+
+    fn beta_prerelease_version(&self) -> u32 {
+        fn extract_beta_rev_from_file<P: AsRef<Path>>(version_file: P) -> Option<String> {
+            let version = fs::read_to_string(version_file).ok()?;
+
+            helpers::extract_beta_rev(&version)
+        }
+
+        if let Some(s) = self.prerelease_version.get() {
+            return s;
+        }
+
+        // First check if there is a version file available.
+        // If available, we read the beta revision from that file.
+        // This only happens when building from a source tarball when Git should not be used.
+        let count = extract_beta_rev_from_file(self.src.join("version")).unwrap_or_else(|| {
+            // Figure out how many merge commits happened since we branched off main.
+            // That's our beta number!
+            // (Note that we use a `..` range, not the `...` symmetric difference.)
+            helpers::git(Some(&self.src))
+                .arg("rev-list")
+                .arg("--count")
+                .arg("--merges")
+                .arg(format!(
+                    "refs/remotes/origin/{}..HEAD",
+                    self.config.stage0_metadata.config.nightly_branch
+                ))
+                .run_in_dry_run()
+                .run_capture(self)
+                .stdout()
+        });
+        let n = count.trim().parse().unwrap();
+        self.prerelease_version.set(Some(n));
+        n
+    }
+
+    /// Returns the value of `release` above for Rust itself.
+    pub(crate) fn rust_release(&self) -> String {
+        self.release(&self.version)
+    }
+
+    /// Returns the "package version" for a component.
+    ///
+    /// The package version is typically what shows up in the names of tarballs.
+    /// For channels like beta/nightly it's just the channel name, otherwise it's the release
+    /// version.
+    pub(crate) fn rust_package_vers(&self) -> String {
+        match &self.config.channel[..] {
+            "stable" => self.version.to_string(),
+            "beta" => "beta".to_string(),
+            "nightly" => "nightly".to_string(),
+            _ => format!("{}-dev", self.version),
+        }
+    }
+
+    /// Returns the `version` string associated with this compiler for Rust
+    /// itself.
+    ///
+    /// Note that this is a descriptive string which includes the commit date,
+    /// sha, version, etc.
+    pub(crate) fn rust_version(&self) -> String {
+        let mut version = self.rust_info().version(self, &self.version);
+        if let Some(ref s) = self.config.description
+            && !s.is_empty()
+        {
+            version.push_str(" (");
+            version.push_str(s);
+            version.push(')');
+        }
+        version
+    }
+
+    /// Returns the full commit hash.
+    pub(crate) fn rust_sha(&self) -> Option<&str> {
+        self.rust_info().sha()
+    }
+
+    /// Returns the `a.b.c` version that the given package is at.
+    pub(crate) fn release_num(&self, package: &str) -> String {
+        if self.config.dry_run() {
+            return "0.0.0 (dry-run)".into();
+        }
+        let toml_file_name = self.src.join(format!("src/tools/{package}/Cargo.toml"));
+        let toml = t!(fs::read_to_string(toml_file_name));
+        for line in toml.lines() {
+            if let Some(stripped) =
+                line.strip_prefix("version = \"").and_then(|s| s.strip_suffix('"'))
+            {
+                return stripped.to_owned();
+            }
+        }
+
+        panic!("failed to find version in {package}'s Cargo.toml")
+    }
+
+    /// Returns `true` if unstable features should be enabled for the compiler
+    /// we're building.
+    pub(crate) fn unstable_features(&self) -> bool {
+        !matches!(&self.config.channel[..], "stable" | "beta")
+    }
+
+    /// Returns a Vec of all the dependencies of the given root crate,
+    /// including transitive dependencies and the root itself. Only includes
+    /// "local" crates (those in the local source tree, not from a registry).
+    pub(crate) fn in_tree_crates(
+        &self,
+        root: &str,
+        target: Option<TargetSelection>,
+    ) -> Vec<&Crate> {
+        let mut ret = Vec::new();
+        let mut list = vec![root.to_owned()];
+        let mut visited = HashSet::new();
+        while let Some(krate) = list.pop() {
+            let krate = self
+                .crates
+                .get(&krate)
+                .unwrap_or_else(|| panic!("metadata missing for {krate}: {:?}", self.crates));
+            ret.push(krate);
+            for dep in &krate.deps {
+                if !self.crates.contains_key(dep) {
+                    // Ignore non-workspace members.
+                    continue;
+                }
+                // Don't include optional deps if their features are not
+                // enabled. Ideally this would be computed from `cargo
+                // metadata --features …`, but that is somewhat slow. In
+                // the future, we may want to consider just filtering all
+                // build and dev dependencies in metadata::build.
+                if visited.insert(dep)
+                    && (dep != "profiler_builtins"
+                        || target
+                            .map(|t| self.config.profiler_enabled(t))
+                            .unwrap_or_else(|| self.config.any_profiler_enabled()))
+                    && (dep != "rustc_codegen_llvm"
+                        || self.config.hosts.iter().any(|host| self.config.llvm_enabled(*host)))
+                {
+                    list.push(dep.clone());
+                }
+            }
+        }
+
+        // Sort the crates so that bootstrap unit tests can assume a deterministic order.
+        ret.sort_unstable_by(|a, b| Ord::cmp(&a.name, &b.name));
+        ret
+    }
+
+    pub(crate) fn read_stamp_file(&self, stamp: &BuildStamp) -> Vec<(PathBuf, DependencyType)> {
+        if self.config.dry_run() {
+            return Vec::new();
+        }
+
+        if !stamp.path().exists() {
+            eprintln!(
+                "ERROR: Unable to find the stamp file {}, did you try to keep a nonexistent build stage?",
+                stamp.path().display()
+            );
+            helpers::exit_process(1);
+        }
+
+        let mut paths = Vec::new();
+        let contents = t!(fs::read(stamp.path()), stamp.path());
+        // This is the method we use for extracting paths from the stamp file passed to us. See
+        // run_cargo for more information (in compile.rs).
+        for part in contents.split(|b| *b == 0) {
+            if part.is_empty() {
+                continue;
+            }
+            let dependency_type = match part[0] as char {
+                'h' => DependencyType::Host,
+                's' => DependencyType::TargetSelfContained,
+                't' => DependencyType::Target,
+                _ => unreachable!(),
+            };
+            let path = PathBuf::from(t!(str::from_utf8(&part[1..])));
+            paths.push((path, dependency_type));
+        }
+        paths
+    }
+
+    /// Copies a file from `src` to `dst`.
+    ///
+    /// If `src` is a symlink, `src` will be resolved to the actual path
+    /// and copied to `dst` instead of the symlink itself.
+    #[track_caller]
+    pub(crate) fn resolve_symlink_and_copy(&self, src: &Path, dst: &Path) {
+        self.copy_link_internal(src, dst, true);
+    }
+
+    /// Links a file from `src` to `dst`.
+    /// Attempts to use hard links if possible, falling back to copying.
+    /// You can neither rely on this being a copy nor it being a link,
+    /// so do not write to dst.
+    #[track_caller]
+    pub(crate) fn copy_link(&self, src: &Path, dst: &Path, file_type: FileType) {
+        self.copy_link_internal(src, dst, false);
+
+        if file_type.could_have_split_debuginfo()
+            && let Some(dbg_file) = split_debuginfo(src)
+        {
+            self.copy_link_internal(
+                &dbg_file,
+                &dst.with_extension(dbg_file.extension().unwrap()),
+                false,
+            );
+        }
+    }
+
+    #[track_caller]
+    fn copy_link_internal(&self, src: &Path, dst: &Path, dereference_symlinks: bool) {
+        if self.config.dry_run() {
+            return;
+        }
+        if src == dst {
+            return;
+        }
+
+        #[cfg(feature = "tracing")]
+        let _span = trace_io!("file-copy-link", ?src, ?dst);
+
+        if let Err(e) = fs::remove_file(dst)
+            && cfg!(windows)
+            && e.kind() != io::ErrorKind::NotFound
+        {
+            // workaround for https://github.com/rust-lang/rust/issues/127126
+            // if removing the file fails, attempt to rename it instead.
+            let now = t!(SystemTime::now().duration_since(SystemTime::UNIX_EPOCH));
+            let _ = fs::rename(dst, format!("{}-{}", dst.display(), now.as_nanos()));
+        }
+        let mut metadata = t!(src.symlink_metadata(), format!("src = {}", src.display()));
+        let mut src = src.to_path_buf();
+        if metadata.file_type().is_symlink() {
+            if dereference_symlinks {
+                src = t!(fs::canonicalize(src));
+                metadata = t!(fs::metadata(&src), format!("target = {}", src.display()));
+            } else {
+                let link = t!(fs::read_link(src));
+                t!(self.symlink_file(link, dst));
+                return;
+            }
+        }
+        if let Ok(()) = fs::hard_link(&src, dst) {
+            // Attempt to "easy copy" by creating a hard link (symlinks are privileged on windows),
+            // but if that fails just fall back to a slow `copy` operation.
+        } else {
+            if let Err(e) = fs::copy(&src, dst) {
+                panic!("failed to copy `{}` to `{}`: {}", src.display(), dst.display(), e)
+            }
+            t!(fs::set_permissions(dst, metadata.permissions()));
+
+            // Restore file times because changing permissions on e.g. Linux using `chmod` can cause
+            // file access time to change.
+            let file_times = fs::FileTimes::new()
+                .set_accessed(t!(metadata.accessed()))
+                .set_modified(t!(metadata.modified()));
+            t!(set_file_times(dst, file_times));
+        }
+    }
+
+    /// Links the `src` directory recursively to `dst`. Both are assumed to exist
+    /// when this function is called.
+    /// Will attempt to use hard links if possible and fall back to copying.
+    #[track_caller]
+    pub(crate) fn cp_link_r(&self, src: &Path, dst: &Path) {
+        if self.config.dry_run() {
+            return;
+        }
+        for f in self.read_dir(src) {
+            let path = f.path();
+            let name = path.file_name().unwrap();
+            let dst = dst.join(name);
+            if t!(f.file_type()).is_dir() {
+                t!(fs::create_dir_all(&dst));
+                self.cp_link_r(&path, &dst);
+            } else {
+                self.copy_link(&path, &dst, FileType::Regular);
+            }
+        }
+    }
+
+    /// Copies the `src` directory recursively to `dst`. Both are assumed to exist
+    /// when this function is called.
+    /// Will attempt to use hard links if possible and fall back to copying.
+    /// Unwanted files or directories can be skipped
+    /// by returning `false` from the filter function.
+    #[track_caller]
+    pub(crate) fn cp_link_filtered(&self, src: &Path, dst: &Path, filter: &dyn Fn(&Path) -> bool) {
+        // Immediately recurse with an empty relative path
+        self.cp_link_filtered_recurse(src, dst, Path::new(""), filter)
+    }
+
+    // Inner function does the actual work
+    #[track_caller]
+    fn cp_link_filtered_recurse(
+        &self,
+        src: &Path,
+        dst: &Path,
+        relative: &Path,
+        filter: &dyn Fn(&Path) -> bool,
+    ) {
+        for f in self.read_dir(src) {
+            let path = f.path();
+            let name = path.file_name().unwrap();
+            let dst = dst.join(name);
+            let relative = relative.join(name);
+            // Only copy file or directory if the filter function returns true
+            if filter(&relative) {
+                if t!(f.file_type()).is_dir() {
+                    let _ = fs::remove_dir_all(&dst);
+                    self.create_dir(&dst);
+                    self.cp_link_filtered_recurse(&path, &dst, &relative, filter);
+                } else {
+                    self.copy_link(&path, &dst, FileType::Regular);
+                }
+            }
+        }
+    }
+
+    pub(crate) fn copy_link_to_folder(&self, src: &Path, dest_folder: &Path) {
+        let file_name = src.file_name().unwrap();
+        let dest = dest_folder.join(file_name);
+        self.copy_link(src, &dest, FileType::Regular);
+    }
+
+    pub(crate) fn install(&self, src: &Path, dstdir: &Path, file_type: FileType) {
+        if self.config.dry_run() {
+            return;
+        }
+        let dst = dstdir.join(src.file_name().unwrap());
+
+        #[cfg(feature = "tracing")]
+        let _span = trace_io!("install", ?src, ?dst);
+
+        t!(fs::create_dir_all(dstdir));
+        if !src.exists() {
+            panic!("ERROR: File \"{}\" not found!", src.display());
+        }
+
+        self.copy_link_internal(src, &dst, true);
+        chmod(&dst, file_type.perms());
+
+        // If this file can have debuginfo, look for split debuginfo and install it too.
+        if file_type.could_have_split_debuginfo()
+            && let Some(dbg_file) = split_debuginfo(src)
+        {
+            self.install(&dbg_file, dstdir, FileType::Regular);
+        }
+    }
+
+    pub(crate) fn read(&self, path: &Path) -> String {
+        if self.config.dry_run() {
+            return String::new();
+        }
+        t!(fs::read_to_string(path))
+    }
+
+    #[track_caller]
+    pub(crate) fn create_dir(&self, dir: &Path) {
+        if self.config.dry_run() {
+            return;
+        }
+
+        #[cfg(feature = "tracing")]
+        let _span = trace_io!("dir-create", ?dir);
+
+        t!(fs::create_dir_all(dir))
+    }
+
+    pub(crate) fn remove_dir(&self, dir: &Path) {
+        if self.config.dry_run() {
+            return;
+        }
+
+        #[cfg(feature = "tracing")]
+        let _span = trace_io!("dir-remove", ?dir);
+
+        t!(fs::remove_dir_all(dir))
+    }
+
+    /// Make sure that `dir` will be an empty existing directory after this function ends.
+    /// If it existed before, it will be first deleted.
+    pub(crate) fn clear_dir(&self, dir: &Path) {
+        if self.config.dry_run() {
+            return;
+        }
+
+        #[cfg(feature = "tracing")]
+        let _span = trace_io!("dir-clear", ?dir);
+
+        let _ = std::fs::remove_dir_all(dir);
+        self.create_dir(dir);
+    }
+
+    pub(crate) fn read_dir(&self, dir: &Path) -> impl Iterator<Item = fs::DirEntry> {
+        let iter = match fs::read_dir(dir) {
+            Ok(v) => v,
+            Err(_) if self.config.dry_run() => return vec![].into_iter(),
+            Err(err) => panic!("could not read dir {dir:?}: {err:?}"),
+        };
+        iter.map(|e| t!(e)).collect::<Vec<_>>().into_iter()
+    }
+
+    pub(crate) fn symlink_file<P: AsRef<Path>, Q: AsRef<Path>>(
+        &self,
+        src: P,
+        link: Q,
+    ) -> io::Result<()> {
+        #[cfg(unix)]
+        use std::os::unix::fs::symlink as symlink_file;
+        #[cfg(windows)]
+        use std::os::windows::fs::symlink_file;
+        if !self.config.dry_run() { symlink_file(src.as_ref(), link.as_ref()) } else { Ok(()) }
+    }
+
+    /// Returns if config.ninja is enabled, and checks for ninja existence,
+    /// exiting with a nicer error message if not.
+    pub(crate) fn ninja(&self) -> bool {
+        let mut cmd_finder = crate::core::sanity::Finder::new();
+
+        if self.config.ninja_in_file {
+            // Some Linux distros rename `ninja` to `ninja-build`.
+            // CMake can work with either binary name.
+            if cmd_finder.maybe_have("ninja-build").is_none()
+                && cmd_finder.maybe_have("ninja").is_none()
+            {
+                eprintln!(
+                    "
+Couldn't find required command: ninja (or ninja-build)
+
+You should install ninja as described at
+<https://github.com/ninja-build/ninja/wiki/Pre-built-Ninja-packages>,
+or set `ninja = false` in the `[llvm]` section of `bootstrap.toml`.
+Alternatively, set `download-ci-llvm = true` in that `[llvm]` section
+to download LLVM rather than building it.
+"
+                );
+                helpers::exit_process(1);
+            }
+        }
+
+        // If ninja isn't enabled but we're building for MSVC then we try
+        // doubly hard to enable it. It was realized in #43767 that the msbuild
+        // CMake generator for MSVC doesn't respect configuration options like
+        // disabling LLVM assertions, which can often be quite important!
+        //
+        // In these cases we automatically enable Ninja if we find it in the
+        // environment.
+        if !self.config.ninja_in_file
+            && self.config.host_target.is_msvc()
+            && cmd_finder.maybe_have("ninja").is_some()
+        {
+            return true;
+        }
+
+        self.config.ninja_in_file
+    }
+
+    pub(crate) fn colored_stdout<R, F: FnOnce(&mut dyn WriteColor) -> R>(&self, f: F) -> R {
+        self.colored_stream_inner(StandardStream::stdout, self.config.stdout_is_tty, f)
+    }
+
+    #[expect(dead_code, reason = "symmetric with `colored_stdout`")]
+    pub(crate) fn colored_stderr<R, F: FnOnce(&mut dyn WriteColor) -> R>(&self, f: F) -> R {
+        self.colored_stream_inner(StandardStream::stderr, self.config.stderr_is_tty, f)
+    }
+
+    fn colored_stream_inner<R, F, C>(&self, constructor: C, is_tty: bool, f: F) -> R
+    where
+        C: Fn(ColorChoice) -> StandardStream,
+        F: FnOnce(&mut dyn WriteColor) -> R,
+    {
+        let choice = match self.config.color {
+            flags::Color::Always => ColorChoice::Always,
+            flags::Color::Never => ColorChoice::Never,
+            flags::Color::Auto if !is_tty => ColorChoice::Never,
+            flags::Color::Auto => ColorChoice::Auto,
+        };
+        let mut stream = constructor(choice);
+        let result = f(&mut stream);
+        stream.reset().unwrap();
+        result
+    }
+
+    #[cfg_attr(not(feature = "tracing"), expect(dead_code))]
+    pub(crate) fn report_summary(&self, path: &Path, start_time: Instant) {
+        self.config.exec_ctx.profiler().report_summary(path, start_time);
+    }
+
+    #[cfg(feature = "tracing")]
+    pub(crate) fn report_step_graph(self, directory: &Path) {
+        self.step_graph.into_inner().store_to_dot_files(directory);
+    }
+}
+
+impl AsRef<ExecutionContext> for Build {
+    fn as_ref(&self) -> &ExecutionContext {
+        &self.config.exec_ctx
+    }
+}
+
+#[cfg(unix)]
+fn chmod(path: &Path, perms: u32) {
+    use std::os::unix::fs::*;
+    t!(fs::set_permissions(path, fs::Permissions::from_mode(perms)));
+}
+#[cfg(windows)]
+fn chmod(_path: &Path, _perms: u32) {}
diff --git a/src/bootstrap/src/lib.rs b/src/bootstrap/src/lib.rs
index 92e36155ffa22..cafe81af4d56e 100644
--- a/src/bootstrap/src/lib.rs
+++ b/src/bootstrap/src/lib.rs
@@ -21,1856 +21,6 @@
 #![allow(clippy::map_clone, reason = "false positive for `|x: &&Foo| Foo::clone(x)`")]
 // tidy-alphabetical-end
 
-use std::cell::Cell;
-use std::collections::{BTreeSet, HashMap, HashSet};
-use std::fmt::Display;
-use std::path::{Path, PathBuf};
-use std::sync::OnceLock;
-use std::time::{Instant, SystemTime};
-use std::{env, fs, io, str};
-
-use build_helper::ci::gha;
-use termcolor::{ColorChoice, StandardStream, WriteColor};
-#[cfg(feature = "tracing")]
-use tracing::{instrument, span};
-
-use crate::core::build_steps::format::InternalRustfmt;
-use crate::core::build_steps::test::TestTarget;
-use crate::core::build_steps::vendor::VENDOR_DIR;
-use crate::core::builder::{Builder, Kind};
-use crate::core::compiler::Compiler;
-use crate::core::config::flags::{self, Subcommand};
-use crate::core::config::{BootstrapOverrideLld, Config, DryRun, LlvmLibunwind, TargetSelection};
-use crate::core::metadata::Crate;
-use crate::utils::build_stamp::BuildStamp;
-use crate::utils::channel::GitInfo;
-use crate::utils::exec::{BootstrapCommand, ExecutionContext, command};
-use crate::utils::helpers::{
-    self, dir_is_empty, exe, libdir, set_file_times, split_debuginfo, symlink_dir, t,
-};
-
 pub mod cli_main;
 mod core;
 mod utils;
-
-pub enum GitRepo {
-    Rustc,
-    Llvm,
-}
-
-/// Global configuration for the build system.
-///
-/// This structure transitively contains all configuration for the build system.
-/// All filesystem-encoded configuration is in `config`, all flags are in
-/// `flags`, and then parsed or probed information is listed in the keys below.
-///
-/// This structure is a parameter of almost all methods in the build system,
-/// although most functions are implemented as free functions rather than
-/// methods specifically on this structure itself (to make it easier to
-/// organize).
-pub struct Build {
-    /// User-specified configuration from `bootstrap.toml`.
-    config: Config,
-
-    // Version information
-    version: String,
-
-    // Properties derived from the above configuration
-    src: PathBuf,
-    out: PathBuf,
-    bootstrap_out: PathBuf,
-    cargo_info: GitInfo,
-    rust_analyzer_info: GitInfo,
-    clippy_info: GitInfo,
-    miri_info: GitInfo,
-    rustfmt_info: GitInfo,
-    enzyme_info: GitInfo,
-    in_tree_llvm_info: GitInfo,
-    in_tree_gcc_info: GitInfo,
-    local_rebuild: bool,
-    fail_fast: bool,
-    test_target: TestTarget,
-    verbosity: usize,
-
-    /// Build triple for the pre-compiled snapshot compiler.
-    host_target: TargetSelection,
-    /// Which triples to produce a compiler toolchain for.
-    hosts: Vec<TargetSelection>,
-    /// Which triples to build libraries (core/alloc/std/test/proc_macro) for.
-    targets: Vec<TargetSelection>,
-
-    initial_rustc: PathBuf,
-    initial_rustdoc: PathBuf,
-    initial_cargo: PathBuf,
-    initial_lld: PathBuf,
-    initial_relative_libdir: PathBuf,
-    initial_sysroot: PathBuf,
-
-    // Runtime state filled in later on
-    // C/C++ compilers and archiver for all targets
-    cc: HashMap<TargetSelection, cc::Tool>,
-    cxx: HashMap<TargetSelection, cc::Tool>,
-    ar: HashMap<TargetSelection, PathBuf>,
-    ranlib: HashMap<TargetSelection, PathBuf>,
-    wasi_sdk_path: Option<PathBuf>,
-
-    // Miscellaneous
-    // allow bidirectional lookups: both name -> path and path -> name
-    crates: HashMap<String, Crate>,
-    crate_paths: HashMap<PathBuf, String>,
-    is_sudo: bool,
-    prerelease_version: Cell<Option<u32>>,
-
-    #[cfg(feature = "build-metrics")]
-    metrics: crate::utils::metrics::BuildMetrics,
-
-    #[cfg(feature = "tracing")]
-    step_graph: std::cell::RefCell<crate::utils::step_graph::StepGraph>,
-}
-
-/// When building Rust various objects are handled differently.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
-pub enum DependencyType {
-    /// Libraries originating from proc-macros.
-    Host,
-    /// Typical Rust libraries.
-    Target,
-    /// Non Rust libraries and objects shipped to ease usage of certain targets.
-    TargetSelfContained,
-}
-
-/// The various "modes" of invoking Cargo.
-///
-/// These entries currently correspond to the various output directories of the
-/// build system, with each mod generating output in a different directory.
-#[derive(Debug, Hash, Clone, Copy, PartialEq, Eq)]
-pub enum Mode {
-    /// Build the standard library, placing output in the "stageN-std" directory.
-    Std,
-
-    /// Build librustc, and compiler libraries, placing output in the "stageN-rustc" directory.
-    Rustc,
-
-    /// Build a codegen backend for rustc, placing the output in the "stageN-codegen" directory.
-    Codegen,
-
-    /// Build a tool, placing output in the "bootstrap-tools"
-    /// directory. This is for miscellaneous sets of tools that extend
-    /// bootstrap.
-    ///
-    /// These tools are intended to be only executed on the host system that
-    /// invokes bootstrap, and they thus cannot be cross-compiled.
-    ///
-    /// They are always built using the stage0 compiler, and they
-    /// can be compiled with stable Rust.
-    ///
-    /// These tools also essentially do not participate in staging.
-    ToolBootstrap,
-
-    /// Build a cross-compilable helper tool. These tools do not depend on unstable features or
-    /// compiler internals, but they might be cross-compilable (so we cannot build them using the
-    /// stage0 compiler, unlike `ToolBootstrap`).
-    ///
-    /// Some of these tools are also shipped in our `dist` archives.
-    /// While we could compile them using the stage0 compiler when not cross-compiling, we instead
-    /// use the in-tree compiler (and std) to build them, so that we can ship e.g. std security
-    /// fixes and avoid depending fully on stage0 for the artifacts that we ship.
-    ///
-    /// This mode is used e.g. for linkers and linker tools invoked by rustc on its host target.
-    ToolTarget,
-
-    /// Build a tool which uses the locally built std, placing output in the
-    /// "stageN-tools" directory. Its usage is quite rare; historically it was
-    /// needed by compiletest, but now it is mainly used by `test-float-parse`.
-    ToolStd,
-
-    /// Build a tool which uses the `rustc_private` mechanism, and thus
-    /// the locally built rustc rlib artifacts,
-    /// placing the output in the "stageN-tools" directory. This is used for
-    /// everything that links to rustc as a library, such as rustdoc, clippy,
-    /// rustfmt, miri, etc.
-    ToolRustcPrivate,
-}
-
-impl Mode {
-    pub fn must_support_dlopen(&self) -> bool {
-        match self {
-            Mode::Std | Mode::Codegen => true,
-            Mode::ToolBootstrap
-            | Mode::ToolRustcPrivate
-            | Mode::ToolStd
-            | Mode::ToolTarget
-            | Mode::Rustc => false,
-        }
-    }
-}
-
-/// When `rust.rust_remap_debuginfo` is requested, the compiler needs to know how to
-/// opportunistically unremap compiler vs non-compiler sources. We use two schemes,
-/// [`RemapScheme::Compiler`] and [`RemapScheme::NonCompiler`].
-pub enum RemapScheme {
-    /// The [`RemapScheme::Compiler`] scheme will remap to `/rustc-dev/{hash}`.
-    Compiler,
-    /// The [`RemapScheme::NonCompiler`] scheme will remap to `/rustc/{hash}`.
-    NonCompiler,
-}
-
-#[derive(Debug, Hash, Clone, Copy, PartialEq, Eq)]
-pub enum CLang {
-    C,
-    Cxx,
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum FileType {
-    /// An executable binary file (like a `.exe`).
-    Executable,
-    /// A native, binary library file (like a `.so`, `.dll`, `.a`, `.lib` or `.o`).
-    NativeLibrary,
-    /// An executable (non-binary) script file (like a `.py` or `.sh`).
-    Script,
-    /// Any other regular file that is non-executable.
-    Regular,
-}
-
-impl FileType {
-    /// Get Unix permissions appropriate for this file type.
-    pub fn perms(self) -> u32 {
-        match self {
-            FileType::Executable | FileType::Script => 0o755,
-            FileType::Regular | FileType::NativeLibrary => 0o644,
-        }
-    }
-
-    pub fn could_have_split_debuginfo(self) -> bool {
-        match self {
-            FileType::Executable | FileType::NativeLibrary => true,
-            FileType::Script | FileType::Regular => false,
-        }
-    }
-}
-
-macro_rules! forward {
-    ( $( $fn:ident( $($param:ident: $ty:ty),* ) $( -> $ret:ty)? ),+ $(,)? ) => {
-        impl Build {
-            $( fn $fn(&self, $($param: $ty),* ) $( -> $ret)? {
-                self.config.$fn( $($param),* )
-            } )+
-        }
-    }
-}
-
-forward! {
-    do_if_verbose(f: impl Fn()),
-    is_verbose() -> bool,
-    create(path: &Path, s: &str),
-    remove(f: &Path),
-    tempdir() -> PathBuf,
-    download_rustc() -> bool,
-}
-
-/// An alternative way of specifying what target and stage is involved in some bootstrap activity.
-/// Ideally using a `Compiler` directly should be preferred.
-struct TargetAndStage {
-    target: TargetSelection,
-    stage: u32,
-}
-
-impl From<(TargetSelection, u32)> for TargetAndStage {
-    fn from((target, stage): (TargetSelection, u32)) -> Self {
-        Self { target, stage }
-    }
-}
-
-impl From<Compiler> for TargetAndStage {
-    fn from(compiler: Compiler) -> Self {
-        Self { target: compiler.host, stage: compiler.stage }
-    }
-}
-
-impl Build {
-    /// Creates a new set of build configuration from the `flags` on the command
-    /// line and the filesystem `config`.
-    ///
-    /// By default all build output will be placed in the current directory.
-    pub(crate) fn new(mut config: Config) -> Build {
-        let src = config.src.clone();
-        let out = config.out.clone();
-
-        #[cfg(unix)]
-        // keep this consistent with the equivalent check in x.py:
-        // https://github.com/rust-lang/rust/blob/a8a33cf27166d3eabaffc58ed3799e054af3b0c6/src/bootstrap/bootstrap.py#L796-L797
-        let is_sudo = match env::var_os("SUDO_USER") {
-            Some(_sudo_user) => {
-                // SAFETY: getuid() system call is always successful and no return value is reserved
-                // to indicate an error.
-                //
-                // For more context, see https://man7.org/linux/man-pages/man2/geteuid.2.html
-                let uid = unsafe { libc::getuid() };
-                uid == 0
-            }
-            None => false,
-        };
-        #[cfg(not(unix))]
-        let is_sudo = false;
-
-        let rust_info = config.rust_info.clone();
-        let cargo_info = config.cargo_info.clone();
-        let rust_analyzer_info = config.rust_analyzer_info.clone();
-        let clippy_info = config.clippy_info.clone();
-        let miri_info = config.miri_info.clone();
-        let rustfmt_info = config.rustfmt_info.clone();
-        let enzyme_info = config.enzyme_info.clone();
-        let in_tree_llvm_info = config.in_tree_llvm_info.clone();
-        let in_tree_gcc_info = config.in_tree_gcc_info.clone();
-
-        let initial_target_libdir = command(&config.initial_rustc)
-            .run_in_dry_run()
-            .args(["--print", "target-libdir"])
-            .run_capture_stdout(&config)
-            .stdout()
-            .trim()
-            .to_owned();
-
-        let initial_target_dir = Path::new(&initial_target_libdir)
-            .parent()
-            .unwrap_or_else(|| panic!("{initial_target_libdir} has no parent"));
-
-        let initial_lld = initial_target_dir.join("bin").join("rust-lld");
-
-        let initial_relative_libdir = if cfg!(test) {
-            // On tests, bootstrap uses the shim rustc, not the one from the stage0 toolchain.
-            PathBuf::default()
-        } else {
-            let ancestor = initial_target_dir.ancestors().nth(2).unwrap_or_else(|| {
-                panic!("Not enough ancestors for {}", initial_target_dir.display())
-            });
-
-            ancestor
-                .strip_prefix(&config.initial_sysroot)
-                .unwrap_or_else(|_| {
-                    panic!(
-                        "Couldn’t resolve the initial relative libdir from {}",
-                        initial_target_dir.display()
-                    )
-                })
-                .to_path_buf()
-        };
-
-        let version = std::fs::read_to_string(src.join("src").join("version"))
-            .expect("failed to read src/version");
-        let version = version.trim();
-
-        let mut bootstrap_out = std::env::current_exe()
-            .expect("could not determine path to running process")
-            .parent()
-            .unwrap()
-            .to_path_buf();
-        // Since bootstrap is hardlink to deps/bootstrap-*, Solaris can sometimes give
-        // path with deps/ which is bad and needs to be avoided.
-        if bootstrap_out.ends_with("deps") {
-            bootstrap_out.pop();
-        }
-        if !bootstrap_out.join(exe("rustc", config.host_target)).exists() && !cfg!(test) {
-            // this restriction can be lifted whenever https://github.com/rust-lang/rfcs/pull/3028 is implemented
-            panic!(
-                "`rustc` not found in {}, run `cargo build --bins` before `cargo run`",
-                bootstrap_out.display()
-            )
-        }
-
-        if rust_info.is_from_tarball() && config.description.is_none() {
-            config.description = Some("built from a source tarball".to_owned());
-        }
-
-        let mut build = Build {
-            initial_lld,
-            initial_relative_libdir,
-            initial_rustc: config.initial_rustc.clone(),
-            initial_rustdoc: config.initial_rustdoc.clone(),
-            initial_cargo: config.initial_cargo.clone(),
-            initial_sysroot: config.initial_sysroot.clone(),
-            local_rebuild: config.local_rebuild,
-            fail_fast: config.cmd.fail_fast(),
-            test_target: config.cmd.test_target(),
-            verbosity: config.exec_ctx.verbosity as usize,
-
-            host_target: config.host_target,
-            hosts: config.hosts.clone(),
-            targets: config.targets.clone(),
-
-            config,
-            version: version.to_string(),
-            src,
-            out,
-            bootstrap_out,
-
-            cargo_info,
-            rust_analyzer_info,
-            clippy_info,
-            miri_info,
-            rustfmt_info,
-            enzyme_info,
-            in_tree_llvm_info,
-            in_tree_gcc_info,
-            cc: HashMap::new(),
-            cxx: HashMap::new(),
-            ar: HashMap::new(),
-            ranlib: HashMap::new(),
-            wasi_sdk_path: env::var_os("WASI_SDK_PATH").map(PathBuf::from),
-            crates: HashMap::new(),
-            crate_paths: HashMap::new(),
-            is_sudo,
-            prerelease_version: Cell::new(None),
-
-            #[cfg(feature = "build-metrics")]
-            metrics: crate::utils::metrics::BuildMetrics::init(),
-
-            #[cfg(feature = "tracing")]
-            step_graph: std::cell::RefCell::new(crate::utils::step_graph::StepGraph::default()),
-        };
-
-        // If local-rust is the same major.minor as the current version, then force a
-        // local-rebuild
-        let local_version_verbose = command(&build.initial_rustc)
-            .run_in_dry_run()
-            .args(["--version", "--verbose"])
-            .run_capture_stdout(&build)
-            .stdout();
-        let local_release = local_version_verbose
-            .lines()
-            .filter_map(|x| x.strip_prefix("release:"))
-            .next()
-            .unwrap()
-            .trim();
-        if local_release.split('.').take(2).eq(version.split('.').take(2)) {
-            build.do_if_verbose(|| println!("auto-detected local-rebuild {local_release}"));
-            build.local_rebuild = true;
-        }
-
-        build.do_if_verbose(|| println!("finding compilers"));
-        crate::utils::cc_detect::fill_compilers(&mut build);
-        // When running `setup`, the profile is about to change, so any requirements we have now may
-        // be different on the next invocation. Don't check for them until the next time x.py is
-        // run. This is ok because `setup` never runs any build commands, so it won't fail if commands are missing.
-        //
-        // Similarly, for `setup` we don't actually need submodules or cargo metadata.
-        if !matches!(build.config.cmd, Subcommand::Setup { .. }) {
-            build.do_if_verbose(|| println!("running sanity check"));
-            crate::core::sanity::check(&mut build);
-
-            // Make sure we update these before gathering metadata so we don't get an error about missing
-            // Cargo.toml files.
-            let rust_submodules = ["library/backtrace"];
-            for s in rust_submodules {
-                build.require_submodule(
-                    s,
-                    Some(
-                        "The submodule is required for the standard library \
-                         and the main Cargo workspace.",
-                    ),
-                );
-            }
-            // Now, update all existing submodules.
-            build.update_existing_submodules();
-
-            build.do_if_verbose(|| println!("learning about cargo"));
-            crate::core::metadata::build(&mut build);
-        }
-
-        // Create symbolic link to use host sysroot from a consistent path (e.g., in the rust-analyzer config file).
-        let build_triple = build.out.join(build.host_target);
-        t!(fs::create_dir_all(&build_triple));
-        let host = build.out.join("host");
-        if host.is_symlink() {
-            // Left over from a previous build; overwrite it.
-            // This matters if `build.build` has changed between invocations.
-            #[cfg(windows)]
-            t!(fs::remove_dir(&host));
-            #[cfg(not(windows))]
-            t!(fs::remove_file(&host));
-        }
-        t!(
-            symlink_dir(&build.config, &build_triple, &host),
-            format!("symlink_dir({} => {}) failed", host.display(), build_triple.display())
-        );
-
-        build
-    }
-
-    /// Updates a submodule, and exits with a failure if submodule management
-    /// is disabled and the submodule does not exist.
-    ///
-    /// The given submodule name should be its path relative to the root of
-    /// the main repository.
-    ///
-    /// The given `err_hint` will be shown to the user if the submodule is not
-    /// checked out and submodule management is disabled.
-    #[cfg_attr(
-        feature = "tracing",
-        instrument(
-            level = "trace",
-            name = "Build::require_submodule",
-            skip_all,
-            fields(submodule = submodule),
-        ),
-    )]
-    pub fn require_submodule(&self, submodule: &str, err_hint: Option<&str>) {
-        if self.rust_info().is_from_tarball() {
-            return;
-        }
-
-        if self.config.dry_run() {
-            return;
-        }
-
-        // When testing bootstrap itself, it is much faster to ignore
-        // submodules. Almost all Steps work fine without their submodules.
-        if cfg!(test) && !self.config.submodules() {
-            return;
-        }
-        self.config.update_submodule(submodule);
-        let absolute_path = self.config.src.join(submodule);
-        if !absolute_path.exists() || dir_is_empty(&absolute_path) {
-            let maybe_enable = if !self.config.submodules()
-                && self.config.rust_info.is_managed_git_subrepository()
-            {
-                "\nConsider setting `build.submodules = true` or manually initializing the submodules."
-            } else {
-                ""
-            };
-            let err_hint = err_hint.map_or_else(String::new, |e| format!("\n{e}"));
-            eprintln!(
-                "submodule {submodule} does not appear to be checked out, \
-                 but it is required for this step{maybe_enable}{err_hint}"
-            );
-            helpers::exit_process(1);
-        }
-    }
-
-    /// If any submodule has been initialized already, sync it unconditionally.
-    /// This avoids contributors checking in a submodule change by accident.
-    fn update_existing_submodules(&self) {
-        // Avoid running git when there isn't a git checkout, or the user has
-        // explicitly disabled submodules in `bootstrap.toml`.
-        if !self.config.submodules() {
-            return;
-        }
-        let output = helpers::git(Some(&self.src))
-            .args(["config", "--file"])
-            .arg(".gitmodules")
-            .args(["--get-regexp", "path"])
-            .run_capture(self)
-            .stdout();
-        std::thread::scope(|s| {
-            // Look for `submodule.$name.path = $path`
-            // Sample output: `submodule.src/rust-installer.path src/tools/rust-installer`
-            for line in output.lines() {
-                let submodule = line.split_once(' ').unwrap().1;
-                let config = self.config.clone();
-                s.spawn(move || {
-                    Self::update_existing_submodule(&config, submodule);
-                });
-            }
-        });
-    }
-
-    /// Updates the given submodule only if it's initialized already; nothing happens otherwise.
-    pub(crate) fn update_existing_submodule(config: &Config, submodule: &str) {
-        // Avoid running git when there isn't a git checkout.
-        if !config.submodules() {
-            return;
-        }
-
-        if config.git_info(false, Path::new(submodule)).is_managed_git_subrepository() {
-            config.update_submodule(submodule);
-        }
-    }
-
-    /// Executes the entire build, as configured by the flags and configuration.
-    #[cfg_attr(feature = "tracing", instrument(level = "debug", name = "Build::build", skip_all))]
-    pub fn build(&mut self) {
-        trace!("setting up job management");
-        unsafe {
-            crate::utils::job::setup(self);
-        }
-
-        // Handle hard-coded subcommands.
-        {
-            #[cfg(feature = "tracing")]
-            let _hardcoded_span =
-                span!(tracing::Level::DEBUG, "handling hardcoded subcommands (Format, Perf)")
-                    .entered();
-
-            match &self.config.cmd {
-                Subcommand::Format { check, all } => {
-                    let builder = Builder::new(self);
-                    let rustfmt_path = builder.ensure(InternalRustfmt).unwrap_or_else(|| {
-                        eprintln!("fmt error: `x fmt` is not supported on this channel");
-                        helpers::exit_process(1);
-                    });
-                    return crate::core::build_steps::format::format(
-                        &builder,
-                        rustfmt_path,
-                        *check,
-                        *all,
-                        &self.config.paths,
-                    );
-                }
-                Subcommand::Perf(args) => {
-                    return crate::core::build_steps::perf::perf(&Builder::new(self), args);
-                }
-                _cmd => {
-                    debug!(cmd = ?_cmd, "not a hardcoded subcommand; returning to normal handling");
-                }
-            }
-
-            debug!("handling subcommand normally");
-        }
-
-        if !self.config.dry_run() {
-            #[cfg(feature = "tracing")]
-            let _real_run_span = span!(tracing::Level::DEBUG, "executing real run").entered();
-
-            // We first do a dry-run. This is a sanity-check to ensure that
-            // steps don't do anything expensive in the dry-run.
-            {
-                #[cfg(feature = "tracing")]
-                let _sanity_check_span =
-                    span!(tracing::Level::DEBUG, "(1) executing dry-run sanity-check").entered();
-                self.config.set_dry_run(DryRun::SelfCheck);
-                let builder = Builder::new(self);
-                builder.execute_cli();
-            }
-
-            // Actual run.
-            {
-                #[cfg(feature = "tracing")]
-                let _actual_run_span =
-                    span!(tracing::Level::DEBUG, "(2) executing actual run").entered();
-                self.config.set_dry_run(DryRun::Disabled);
-                let builder = Builder::new(self);
-                builder.execute_cli();
-            }
-        } else {
-            #[cfg(feature = "tracing")]
-            let _dry_run_span = span!(tracing::Level::DEBUG, "executing dry run").entered();
-
-            let builder = Builder::new(self);
-            builder.execute_cli();
-        }
-
-        #[cfg(feature = "tracing")]
-        debug!("checking for postponed test failures from `test  --no-fail-fast`");
-
-        // Check for postponed failures from `test --no-fail-fast`.
-        self.config.exec_ctx().report_failures_and_exit();
-
-        #[cfg(feature = "build-metrics")]
-        self.metrics.persist(self);
-    }
-
-    fn rust_info(&self) -> &GitInfo {
-        &self.config.rust_info
-    }
-
-    /// Gets the space-separated set of activated features for the standard library.
-    /// This can be configured with the `std-features` key in bootstrap.toml.
-    fn std_features(&self, target: TargetSelection) -> String {
-        let mut features: BTreeSet<&str> =
-            self.config.rust_std_features.iter().map(|s| s.as_str()).collect();
-
-        match self.config.llvm_libunwind(target) {
-            LlvmLibunwind::InTree => features.insert("llvm-libunwind"),
-            LlvmLibunwind::System => features.insert("system-llvm-libunwind"),
-            LlvmLibunwind::No => false,
-        };
-
-        if self.config.backtrace {
-            features.insert("backtrace");
-        }
-
-        if self.config.profiler_enabled(target) {
-            features.insert("profiler");
-        }
-
-        // If zkvm target, generate memcpy, etc.
-        if target.contains("zkvm") {
-            features.insert("compiler-builtins-mem");
-        }
-
-        features.into_iter().collect::<Vec<_>>().join(" ")
-    }
-
-    /// Gets the space-separated set of activated features for the compiler.
-    fn rustc_features(&self, kind: Kind, target: TargetSelection, crates: &[String]) -> String {
-        let possible_features_by_crates: HashSet<_> = crates
-            .iter()
-            .flat_map(|krate| &self.crates[krate].features)
-            .map(std::ops::Deref::deref)
-            .collect();
-        let check = |feature: &str| -> bool {
-            crates.is_empty() || possible_features_by_crates.contains(feature)
-        };
-        let mut features = vec![];
-
-        if let Some(allocator_feature_name) = self.config.allocator(target).feature_name()
-            && check(allocator_feature_name)
-        {
-            features.push(allocator_feature_name);
-        }
-        if (self.config.llvm_enabled(target) || kind == Kind::Check) && check("llvm") {
-            features.push("llvm");
-        }
-        if self.config.llvm_offload {
-            features.push("llvm_offload");
-        }
-        // keep in sync with `bootstrap/compile.rs:rustc_cargo_env`
-        if self.config.rust_randomize_layout && check("rustc_randomized_layouts") {
-            features.push("rustc_randomized_layouts");
-        }
-        if self.config.compile_time_deps && kind == Kind::Check {
-            features.push("check_only");
-        }
-
-        if crates.iter().any(|c| c == "rustc_transmute") {
-            // for `x test rustc_transmute`, this feature isn't enabled automatically by a
-            // dependent crate.
-            features.push("rustc");
-        }
-
-        // If debug logging is on, then we want the default for tracing:
-        // https://github.com/tokio-rs/tracing/blob/3dd5c03d907afdf2c39444a29931833335171554/tracing/src/level_filters.rs#L26
-        // which is everything (including debug/trace/etc.)
-        // if its unset, if debug_assertions is on, then debug_logging will also be on
-        // as well as tracing *ignoring* this feature when debug_assertions is on
-        if !self.config.rust_debug_logging && check("max_level_info") {
-            features.push("max_level_info");
-        }
-
-        features.join(" ")
-    }
-
-    /// Component directory that Cargo will produce output into (e.g.
-    /// release/debug)
-    fn cargo_dir(&self, mode: Mode) -> &'static str {
-        match (mode, self.config.rust_optimize.is_release()) {
-            (Mode::Std, _) => "dist",
-            (_, true) => "release",
-            (_, false) => "debug",
-        }
-    }
-
-    fn tools_dir(&self, build_compiler: Compiler) -> PathBuf {
-        let out = self
-            .out
-            .join(build_compiler.host)
-            .join(format!("stage{}-tools-bin", build_compiler.stage + 1));
-        t!(fs::create_dir_all(&out));
-        out
-    }
-
-    /// Returns the root directory for all output generated in a particular
-    /// stage when being built with a particular build compiler.
-    ///
-    /// The mode indicates what the root directory is for.
-    fn stage_out(&self, build_compiler: Compiler, mode: Mode) -> PathBuf {
-        use std::fmt::Write;
-
-        fn bootstrap_tool() -> (Option<u32>, &'static str) {
-            (None, "bootstrap-tools")
-        }
-        fn staged_tool(build_compiler: Compiler) -> (Option<u32>, &'static str) {
-            (Some(build_compiler.stage + 1), "tools")
-        }
-
-        let (stage, suffix) = match mode {
-            // Std is special, stage N std is built with stage N rustc
-            Mode::Std => (Some(build_compiler.stage), "std"),
-            // The rest of things are built with stage N-1 rustc
-            Mode::Rustc => (Some(build_compiler.stage + 1), "rustc"),
-            Mode::Codegen => (Some(build_compiler.stage + 1), "codegen"),
-            Mode::ToolBootstrap => bootstrap_tool(),
-            Mode::ToolStd | Mode::ToolRustcPrivate => (Some(build_compiler.stage + 1), "tools"),
-            Mode::ToolTarget => {
-                // If we're not cross-compiling (the common case), share the target directory with
-                // bootstrap tools to reuse the build cache.
-                if build_compiler.stage == 0 {
-                    bootstrap_tool()
-                } else {
-                    staged_tool(build_compiler)
-                }
-            }
-        };
-        let path = self.out.join(build_compiler.host);
-        let mut dir_name = String::new();
-        if let Some(stage) = stage {
-            write!(dir_name, "stage{stage}-").unwrap();
-        }
-        dir_name.push_str(suffix);
-        path.join(dir_name)
-    }
-
-    /// Returns the root output directory for all Cargo output in a given stage,
-    /// running a particular compiler, whether or not we're building the
-    /// standard library, and targeting the specified architecture.
-    fn cargo_out(&self, build_compiler: Compiler, mode: Mode, target: TargetSelection) -> PathBuf {
-        self.stage_out(build_compiler, mode).join(target).join(self.cargo_dir(mode))
-    }
-
-    /// Output directory for all documentation for a target
-    fn doc_out(&self, target: TargetSelection) -> PathBuf {
-        self.out.join(target).join("doc")
-    }
-
-    /// Output directory for all JSON-formatted documentation for a target
-    fn json_doc_out(&self, target: TargetSelection) -> PathBuf {
-        self.out.join(target).join("json-doc")
-    }
-
-    fn test_out(&self, target: TargetSelection) -> PathBuf {
-        self.out.join(target).join("test")
-    }
-
-    /// Output directory for all documentation for a target
-    fn compiler_doc_out(&self, target: TargetSelection) -> PathBuf {
-        self.out.join(target).join("compiler-doc")
-    }
-
-    /// Output directory for some generated md crate documentation for a target (temporary)
-    fn md_doc_out(&self, target: TargetSelection) -> PathBuf {
-        self.out.join(target).join("md-doc")
-    }
-
-    /// Path to the vendored Rust crates.
-    fn vendored_crates_path(&self) -> Option<PathBuf> {
-        if self.config.vendor { Some(self.src.join(VENDOR_DIR)) } else { None }
-    }
-
-    /// Directory for libraries built from C/C++ code and shared between stages.
-    fn native_dir(&self, target: TargetSelection) -> PathBuf {
-        self.out.join(target).join("native")
-    }
-
-    /// Root output directory for rust_test_helpers library compiled for
-    /// `target`
-    fn test_helpers_out(&self, target: TargetSelection) -> PathBuf {
-        self.native_dir(target).join("rust-test-helpers")
-    }
-
-    /// Adds the `RUST_TEST_THREADS` env var if necessary
-    fn add_rust_test_threads(&self, cmd: &mut BootstrapCommand) {
-        if env::var_os("RUST_TEST_THREADS").is_none() {
-            cmd.env("RUST_TEST_THREADS", self.jobs().to_string());
-        }
-    }
-
-    /// Returns the libdir of the snapshot compiler.
-    fn rustc_snapshot_libdir(&self) -> PathBuf {
-        self.rustc_snapshot_sysroot().join(libdir(self.config.host_target))
-    }
-
-    /// Returns the sysroot of the snapshot compiler.
-    fn rustc_snapshot_sysroot(&self) -> &Path {
-        static SYSROOT_CACHE: OnceLock<PathBuf> = OnceLock::new();
-        SYSROOT_CACHE.get_or_init(|| {
-            command(&self.initial_rustc)
-                .run_in_dry_run()
-                .args(["--print", "sysroot"])
-                .run_capture_stdout(self)
-                .stdout()
-                .trim()
-                .to_owned()
-                .into()
-        })
-    }
-
-    fn info(&self, msg: &str) {
-        match self.config.get_dry_run() {
-            DryRun::SelfCheck => (),
-            DryRun::Disabled | DryRun::UserSelected => {
-                println!("{msg}");
-            }
-        }
-    }
-
-    /// Return a `Group` guard for a [`Step`] that:
-    /// - Performs `action`
-    ///   - If the action is `Kind::Test`, use [`Build::msg_test`] instead.
-    /// - On `what`
-    ///   - Where `what` possibly corresponds to a `mode`
-    /// - `action` is performed with/on the given compiler (`target_and_stage`).
-    ///   - Since for some steps it is not possible to pass a single compiler here, it is also
-    ///     possible to pass the host and stage explicitly.
-    /// - With a given `target`.
-    ///
-    /// [`Step`]: crate::core::builder::Step
-    #[must_use = "Groups should not be dropped until the Step finishes running"]
-    #[track_caller]
-    fn msg(
-        &self,
-        action: impl Into<Kind>,
-        what: impl Display,
-        mode: impl Into<Option<Mode>>,
-        target_and_stage: impl Into<TargetAndStage>,
-        target: impl Into<Option<TargetSelection>>,
-    ) -> Option<gha::Group> {
-        let target_and_stage = target_and_stage.into();
-        let action = action.into();
-        assert!(
-            action != Kind::Test,
-            "Please use `Build::msg_test` instead of `Build::msg(Kind::Test)`"
-        );
-
-        let actual_stage = match mode.into() {
-            // Std has the same stage as the compiler that builds it
-            Some(Mode::Std) => target_and_stage.stage,
-            // Other things have stage corresponding to their build compiler + 1
-            Some(
-                Mode::Rustc
-                | Mode::Codegen
-                | Mode::ToolBootstrap
-                | Mode::ToolTarget
-                | Mode::ToolStd
-                | Mode::ToolRustcPrivate,
-            )
-            | None => target_and_stage.stage + 1,
-        };
-
-        let action = action.description();
-        let what = what.to_string();
-        let msg = |fmt| {
-            let space = if !what.is_empty() { " " } else { "" };
-            format!("{action} stage{actual_stage} {what}{space}{fmt}")
-        };
-        let msg = if let Some(target) = target.into() {
-            let build_stage = target_and_stage.stage;
-            let host = target_and_stage.target;
-            if host == target {
-                msg(format_args!("(stage{build_stage} -> stage{actual_stage}, {target})"))
-            } else {
-                msg(format_args!("(stage{build_stage}:{host} -> stage{actual_stage}:{target})"))
-            }
-        } else {
-            msg(format_args!(""))
-        };
-        self.group(&msg)
-    }
-
-    /// Return a `Group` guard for a [`Step`] that tests `what` with the given `stage` and `target`.
-    /// Use this instead of [`Build::msg`] for test steps, because for them it is not always clear
-    /// what exactly is a build compiler.
-    ///
-    /// [`Step`]: crate::core::builder::Step
-    #[must_use = "Groups should not be dropped until the Step finishes running"]
-    #[track_caller]
-    fn msg_test(
-        &self,
-        what: impl Display,
-        target: TargetSelection,
-        stage: u32,
-    ) -> Option<gha::Group> {
-        let action = Kind::Test.description();
-        let msg = format!("{action} stage{stage} {what} ({target})");
-        self.group(&msg)
-    }
-
-    /// Return a `Group` guard for a [`Step`] that is only built once and isn't affected by `--stage`.
-    ///
-    /// [`Step`]: crate::core::builder::Step
-    #[must_use = "Groups should not be dropped until the Step finishes running"]
-    #[track_caller]
-    fn msg_unstaged(
-        &self,
-        action: impl Into<Kind>,
-        what: impl Display,
-        target: TargetSelection,
-    ) -> Option<gha::Group> {
-        let action = action.into().description();
-        let msg = format!("{action} {what} for {target}");
-        self.group(&msg)
-    }
-
-    #[track_caller]
-    fn group(&self, msg: &str) -> Option<gha::Group> {
-        match self.config.get_dry_run() {
-            DryRun::SelfCheck => None,
-            DryRun::Disabled | DryRun::UserSelected => Some(gha::group(msg)),
-        }
-    }
-
-    /// Returns the number of parallel jobs that have been configured for this
-    /// build.
-    fn jobs(&self) -> u32 {
-        self.config.jobs.unwrap_or_else(|| {
-            std::thread::available_parallelism().map_or(1, std::num::NonZeroUsize::get) as u32
-        })
-    }
-
-    fn debuginfo_map_to(&self, which: GitRepo, remap_scheme: RemapScheme) -> Option<String> {
-        if !self.config.rust_remap_debuginfo {
-            return None;
-        }
-
-        match which {
-            GitRepo::Rustc => {
-                let sha = self.rust_sha().unwrap_or(&self.version);
-
-                match remap_scheme {
-                    RemapScheme::Compiler => {
-                        // For compiler sources, remap via `/rustc-dev/{sha}` to allow
-                        // distinguishing between compiler sources vs library sources, since
-                        // `rustc-dev` dist component places them under
-                        // `$sysroot/lib/rustlib/rustc-src/rust` as opposed to `rust-src`'s
-                        // `$sysroot/lib/rustlib/src/rust`.
-                        //
-                        // Keep this scheme in sync with `rustc_metadata::rmeta::decoder`'s
-                        // `try_to_translate_virtual_to_real`.
-                        Some(format!("/rustc-dev/{sha}"))
-                    }
-                    RemapScheme::NonCompiler => {
-                        // For non-compiler sources, use `/rustc/{sha}` remapping scheme.
-                        Some(format!("/rustc/{sha}"))
-                    }
-                }
-            }
-            GitRepo::Llvm => Some(String::from("/rustc/llvm")),
-        }
-    }
-
-    /// Returns the path to the C compiler for the target specified.
-    fn cc(&self, target: TargetSelection) -> PathBuf {
-        if self.config.dry_run() {
-            return PathBuf::new();
-        }
-        self.cc[&target].path().into()
-    }
-
-    /// Returns the internal `cc::Tool` for the C compiler.
-    fn cc_tool(&self, target: TargetSelection) -> cc::Tool {
-        self.cc[&target].clone()
-    }
-
-    /// Returns the internal `cc::Tool` for the C++ compiler.
-    fn cxx_tool(&self, target: TargetSelection) -> cc::Tool {
-        self.cxx[&target].clone()
-    }
-
-    /// Returns C flags that `cc-rs` thinks should be enabled for the
-    /// specified target by default.
-    fn cc_handled_cflags(&self, target: TargetSelection, c: CLang) -> Vec<String> {
-        if self.config.dry_run() {
-            return Vec::new();
-        }
-        let base = match c {
-            CLang::C => self.cc[&target].clone(),
-            CLang::Cxx => self.cxx[&target].clone(),
-        };
-
-        // Filter out -O and /O (the optimization flags) that we picked up
-        // from cc-rs, that's up to the caller to figure out.
-        base.args()
-            .iter()
-            .map(|s| s.to_string_lossy().into_owned())
-            .filter(|s| !s.starts_with("-O") && !s.starts_with("/O"))
-            .collect::<Vec<String>>()
-    }
-
-    /// Returns extra C flags that `cc-rs` doesn't handle.
-    fn cc_unhandled_cflags(
-        &self,
-        target: TargetSelection,
-        which: GitRepo,
-        c: CLang,
-    ) -> Vec<String> {
-        let mut base = Vec::new();
-
-        // If we're compiling C++ on macOS then we add a flag indicating that
-        // we want libc++ (more filled out than libstdc++), ensuring that
-        // LLVM/etc are all properly compiled.
-        if matches!(c, CLang::Cxx) && target.contains("apple-darwin") {
-            base.push("-stdlib=libc++".into());
-        }
-
-        // Work around an apparently bad MinGW / GCC optimization,
-        // See: https://lists.llvm.org/pipermail/cfe-dev/2016-December/051980.html
-        // See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78936
-        if &*target.triple == "i686-pc-windows-gnu" {
-            base.push("-fno-omit-frame-pointer".into());
-        }
-
-        if let Some(map_to) = self.debuginfo_map_to(which, RemapScheme::NonCompiler) {
-            let map = format!("{}={}", self.src.display(), map_to);
-            let cc = self.cc_tool(target);
-            if cc.is_like_clang() || cc.is_like_gnu() {
-                base.push(format!("-fdebug-prefix-map={map}"));
-            } else if cc.is_like_clang_cl() {
-                base.push("-Xclang".into());
-                base.push(format!("-fdebug-prefix-map={map}"));
-            }
-        }
-        base
-    }
-
-    /// Returns the path to the `ar` archive utility for the target specified.
-    fn ar(&self, target: TargetSelection) -> Option<PathBuf> {
-        if self.config.dry_run() {
-            return None;
-        }
-        self.ar.get(&target).cloned()
-    }
-
-    /// Returns the path to the `ranlib` utility for the target specified.
-    fn ranlib(&self, target: TargetSelection) -> Option<PathBuf> {
-        if self.config.dry_run() {
-            return None;
-        }
-        self.ranlib.get(&target).cloned()
-    }
-
-    /// Returns the path to the C++ compiler for the target specified.
-    fn cxx(&self, target: TargetSelection) -> Result<PathBuf, String> {
-        if self.config.dry_run() {
-            return Ok(PathBuf::new());
-        }
-        match self.cxx.get(&target) {
-            Some(p) => Ok(p.path().into()),
-            None => Err(format!("target `{target}` is not configured as a host, only as a target")),
-        }
-    }
-
-    /// Returns the path to the linker for the given target if it needs to be overridden.
-    fn linker(&self, target: TargetSelection) -> Option<PathBuf> {
-        if self.config.dry_run() {
-            return Some(PathBuf::new());
-        }
-        if let Some(linker) = self.config.target_config.get(&target).and_then(|c| c.linker.clone())
-        {
-            Some(linker)
-        } else if target.contains("vxworks") {
-            // need to use CXX compiler as linker to resolve the exception functions
-            // that are only existed in CXX libraries
-            Some(self.cxx[&target].path().into())
-        } else if !self.config.is_host_target(target)
-            && helpers::use_host_linker(target)
-            && !target.is_msvc()
-        {
-            Some(self.cc(target))
-        } else if self.config.bootstrap_override_lld.is_used()
-            && self.is_lld_direct_linker(target)
-            && self.host_target == target
-        {
-            match self.config.bootstrap_override_lld {
-                BootstrapOverrideLld::SelfContained => Some(self.initial_lld.clone()),
-                BootstrapOverrideLld::External => Some("lld".into()),
-                BootstrapOverrideLld::None => None,
-            }
-        } else {
-            None
-        }
-    }
-
-    // Is LLD configured directly through `-Clinker`?
-    // Only MSVC targets use LLD directly at the moment.
-    fn is_lld_direct_linker(&self, target: TargetSelection) -> bool {
-        target.is_msvc()
-    }
-
-    /// Returns if this target should statically link the C runtime, if specified
-    fn crt_static(&self, target: TargetSelection) -> Option<bool> {
-        if target.contains("pc-windows-msvc") {
-            Some(true)
-        } else {
-            self.config.target_config.get(&target).and_then(|t| t.crt_static)
-        }
-    }
-
-    /// Returns the "musl root" for this `target`, if defined.
-    ///
-    /// If this is a native target (host is also musl) and no musl-root is given,
-    /// it falls back to the system toolchain in /usr.
-    fn musl_root(&self, target: TargetSelection) -> Option<&Path> {
-        let configured_root = self
-            .config
-            .target_config
-            .get(&target)
-            .and_then(|t| t.musl_root.as_ref())
-            .or(self.config.musl_root.as_ref())
-            .map(|p| &**p);
-
-        if self.config.is_host_target(target) && configured_root.is_none() {
-            Some(Path::new("/usr"))
-        } else {
-            configured_root
-        }
-    }
-
-    /// Returns the "musl libdir" for this `target`.
-    fn musl_libdir(&self, target: TargetSelection) -> Option<PathBuf> {
-        self.config
-            .target_config
-            .get(&target)
-            .and_then(|t| t.musl_libdir.clone())
-            .or_else(|| self.musl_root(target).map(|root| root.join("lib")))
-    }
-
-    /// Returns the `lib` directory for the WASI target specified, if
-    /// configured.
-    ///
-    /// This first consults `wasi-root` as configured in per-target
-    /// configuration, and failing that it assumes that `$WASI_SDK_PATH` is
-    /// set in the environment, and failing that `None` is returned.
-    fn wasi_libdir(&self, target: TargetSelection) -> Option<PathBuf> {
-        let configured =
-            self.config.target_config.get(&target).and_then(|t| t.wasi_root.as_ref()).map(|p| &**p);
-        if let Some(path) = configured {
-            return Some(path.join("lib").join(target.to_string()));
-        }
-        let mut env_root = self.wasi_sdk_path.clone()?;
-        env_root.push("share");
-        env_root.push("wasi-sysroot");
-        env_root.push("lib");
-        env_root.push(target.to_string());
-        Some(env_root)
-    }
-
-    /// Returns `true` if this is a no-std `target`, if defined
-    fn no_std(&self, target: TargetSelection) -> Option<bool> {
-        self.config.target_config.get(&target).map(|t| t.no_std)
-    }
-
-    /// Returns `true` if the target will be tested using the `remote-test-client`
-    /// and `remote-test-server` binaries.
-    fn remote_tested(&self, target: TargetSelection) -> bool {
-        self.qemu_rootfs(target).is_some()
-            || target.contains("android")
-            || env::var_os("TEST_DEVICE_ADDR").is_some()
-    }
-
-    /// Returns an optional "runner" to pass to `compiletest` when executing
-    /// test binaries.
-    ///
-    /// An example of this would be a WebAssembly runtime when testing the wasm
-    /// targets.
-    fn runner(&self, target: TargetSelection) -> Option<String> {
-        let configured_runner =
-            self.config.target_config.get(&target).and_then(|t| t.runner.as_ref()).map(|p| &**p);
-        if let Some(runner) = configured_runner {
-            return Some(runner.to_owned());
-        }
-
-        if target.starts_with("wasm") && target.contains("wasi") {
-            self.default_wasi_runner(target)
-        } else {
-            None
-        }
-    }
-
-    /// When a `runner` configuration is not provided and a WASI-looking target
-    /// is being tested this is consulted to prove the environment to see if
-    /// there's a runtime already lying around that seems reasonable to use.
-    fn default_wasi_runner(&self, target: TargetSelection) -> Option<String> {
-        let mut finder = crate::core::sanity::Finder::new();
-
-        // Look for Wasmtime, and for its default options be sure to disable
-        // its caching system since we're executing quite a lot of tests and
-        // ideally shouldn't pollute the cache too much.
-        if let Some(path) = finder.maybe_have("wasmtime")
-            && let Ok(mut path) = path.into_os_string().into_string()
-        {
-            path.push_str(" run -Wexceptions -C cache=n --dir .");
-            // Make sure that tests have access to RUSTC_BOOTSTRAP. This (for example) is
-            // required for libtest to work on beta/stable channels.
-            //
-            // NB: with Wasmtime 20 this can change to `-S inherit-env` to
-            // inherit the entire environment rather than just this single
-            // environment variable.
-            path.push_str(" --env RUSTC_BOOTSTRAP");
-
-            if target.contains("wasip2") {
-                path.push_str(" --wasi inherit-network --wasi allow-ip-name-lookup");
-            }
-
-            return Some(path);
-        }
-
-        None
-    }
-
-    /// Returns whether the specified tool is configured as part of this build.
-    ///
-    /// This requires that both the `extended` key is set and the `tools` key is
-    /// either unset or specifically contains the specified tool.
-    fn tool_enabled(&self, tool: &str) -> bool {
-        if !self.config.extended {
-            return false;
-        }
-        match &self.config.tools {
-            Some(set) => set.contains(tool),
-            None => true,
-        }
-    }
-
-    /// Returns the root of the "rootfs" image that this target will be using,
-    /// if one was configured.
-    ///
-    /// If `Some` is returned then that means that tests for this target are
-    /// emulated with QEMU and binaries will need to be shipped to the emulator.
-    fn qemu_rootfs(&self, target: TargetSelection) -> Option<&Path> {
-        self.config.target_config.get(&target).and_then(|t| t.qemu_rootfs.as_ref()).map(|p| &**p)
-    }
-
-    /// Temporary directory that extended error information is emitted to.
-    fn extended_error_dir(&self) -> PathBuf {
-        self.out.join("tmp/extended-error-metadata")
-    }
-
-    /// Tests whether the `compiler` compiling for `target` should be forced to
-    /// use a stage1 compiler instead.
-    ///
-    /// Currently, by default, the build system does not perform a "full
-    /// bootstrap" by default where we compile the compiler three times.
-    /// Instead, we compile the compiler two times. The final stage (stage2)
-    /// just copies the libraries from the previous stage, which is what this
-    /// method detects.
-    ///
-    /// Here we return `true` if:
-    ///
-    /// * The build isn't performing a full bootstrap
-    /// * The `compiler` is in the final stage, 2
-    /// * We're not cross-compiling, so the artifacts are already available in
-    ///   stage1
-    ///
-    /// When all of these conditions are met the build will lift artifacts from
-    /// the previous stage forward.
-    fn force_use_stage1(&self, stage: u32, target: TargetSelection) -> bool {
-        !self.config.full_bootstrap
-            && !self.config.download_rustc()
-            && stage >= 2
-            && (self.hosts.contains(&target) || target == self.host_target)
-    }
-
-    /// Checks whether the `compiler` compiling for `target` should be forced to
-    /// use a stage2 compiler instead.
-    ///
-    /// When we download the pre-compiled version of rustc and compiler stage is >= 2,
-    /// it should be forced to use a stage2 compiler.
-    fn force_use_stage2(&self, stage: u32) -> bool {
-        self.config.download_rustc() && stage >= 2
-    }
-
-    /// Given `num` in the form "a.b.c" return a "release string" which
-    /// describes the release version number.
-    ///
-    /// For example on nightly this returns "a.b.c-nightly", on beta it returns
-    /// "a.b.c-beta.1" and on stable it just returns "a.b.c".
-    fn release(&self, num: &str) -> String {
-        match &self.config.channel[..] {
-            "stable" => num.to_string(),
-            "beta" => {
-                if !self.config.omit_git_hash {
-                    format!("{}-beta.{}", num, self.beta_prerelease_version())
-                } else {
-                    format!("{num}-beta")
-                }
-            }
-            "nightly" => format!("{num}-nightly"),
-            _ => format!("{num}-dev"),
-        }
-    }
-
-    fn beta_prerelease_version(&self) -> u32 {
-        fn extract_beta_rev_from_file<P: AsRef<Path>>(version_file: P) -> Option<String> {
-            let version = fs::read_to_string(version_file).ok()?;
-
-            helpers::extract_beta_rev(&version)
-        }
-
-        if let Some(s) = self.prerelease_version.get() {
-            return s;
-        }
-
-        // First check if there is a version file available.
-        // If available, we read the beta revision from that file.
-        // This only happens when building from a source tarball when Git should not be used.
-        let count = extract_beta_rev_from_file(self.src.join("version")).unwrap_or_else(|| {
-            // Figure out how many merge commits happened since we branched off main.
-            // That's our beta number!
-            // (Note that we use a `..` range, not the `...` symmetric difference.)
-            helpers::git(Some(&self.src))
-                .arg("rev-list")
-                .arg("--count")
-                .arg("--merges")
-                .arg(format!(
-                    "refs/remotes/origin/{}..HEAD",
-                    self.config.stage0_metadata.config.nightly_branch
-                ))
-                .run_in_dry_run()
-                .run_capture(self)
-                .stdout()
-        });
-        let n = count.trim().parse().unwrap();
-        self.prerelease_version.set(Some(n));
-        n
-    }
-
-    /// Returns the value of `release` above for Rust itself.
-    fn rust_release(&self) -> String {
-        self.release(&self.version)
-    }
-
-    /// Returns the "package version" for a component.
-    ///
-    /// The package version is typically what shows up in the names of tarballs.
-    /// For channels like beta/nightly it's just the channel name, otherwise it's the release
-    /// version.
-    fn rust_package_vers(&self) -> String {
-        match &self.config.channel[..] {
-            "stable" => self.version.to_string(),
-            "beta" => "beta".to_string(),
-            "nightly" => "nightly".to_string(),
-            _ => format!("{}-dev", self.version),
-        }
-    }
-
-    /// Returns the `version` string associated with this compiler for Rust
-    /// itself.
-    ///
-    /// Note that this is a descriptive string which includes the commit date,
-    /// sha, version, etc.
-    fn rust_version(&self) -> String {
-        let mut version = self.rust_info().version(self, &self.version);
-        if let Some(ref s) = self.config.description
-            && !s.is_empty()
-        {
-            version.push_str(" (");
-            version.push_str(s);
-            version.push(')');
-        }
-        version
-    }
-
-    /// Returns the full commit hash.
-    fn rust_sha(&self) -> Option<&str> {
-        self.rust_info().sha()
-    }
-
-    /// Returns the `a.b.c` version that the given package is at.
-    fn release_num(&self, package: &str) -> String {
-        if self.config.dry_run() {
-            return "0.0.0 (dry-run)".into();
-        }
-        let toml_file_name = self.src.join(format!("src/tools/{package}/Cargo.toml"));
-        let toml = t!(fs::read_to_string(toml_file_name));
-        for line in toml.lines() {
-            if let Some(stripped) =
-                line.strip_prefix("version = \"").and_then(|s| s.strip_suffix('"'))
-            {
-                return stripped.to_owned();
-            }
-        }
-
-        panic!("failed to find version in {package}'s Cargo.toml")
-    }
-
-    /// Returns `true` if unstable features should be enabled for the compiler
-    /// we're building.
-    fn unstable_features(&self) -> bool {
-        !matches!(&self.config.channel[..], "stable" | "beta")
-    }
-
-    /// Returns a Vec of all the dependencies of the given root crate,
-    /// including transitive dependencies and the root itself. Only includes
-    /// "local" crates (those in the local source tree, not from a registry).
-    fn in_tree_crates(&self, root: &str, target: Option<TargetSelection>) -> Vec<&Crate> {
-        let mut ret = Vec::new();
-        let mut list = vec![root.to_owned()];
-        let mut visited = HashSet::new();
-        while let Some(krate) = list.pop() {
-            let krate = self
-                .crates
-                .get(&krate)
-                .unwrap_or_else(|| panic!("metadata missing for {krate}: {:?}", self.crates));
-            ret.push(krate);
-            for dep in &krate.deps {
-                if !self.crates.contains_key(dep) {
-                    // Ignore non-workspace members.
-                    continue;
-                }
-                // Don't include optional deps if their features are not
-                // enabled. Ideally this would be computed from `cargo
-                // metadata --features …`, but that is somewhat slow. In
-                // the future, we may want to consider just filtering all
-                // build and dev dependencies in metadata::build.
-                if visited.insert(dep)
-                    && (dep != "profiler_builtins"
-                        || target
-                            .map(|t| self.config.profiler_enabled(t))
-                            .unwrap_or_else(|| self.config.any_profiler_enabled()))
-                    && (dep != "rustc_codegen_llvm"
-                        || self.config.hosts.iter().any(|host| self.config.llvm_enabled(*host)))
-                {
-                    list.push(dep.clone());
-                }
-            }
-        }
-
-        // Sort the crates so that bootstrap unit tests can assume a deterministic order.
-        ret.sort_unstable_by(|a, b| Ord::cmp(&a.name, &b.name));
-        ret
-    }
-
-    fn read_stamp_file(&self, stamp: &BuildStamp) -> Vec<(PathBuf, DependencyType)> {
-        if self.config.dry_run() {
-            return Vec::new();
-        }
-
-        if !stamp.path().exists() {
-            eprintln!(
-                "ERROR: Unable to find the stamp file {}, did you try to keep a nonexistent build stage?",
-                stamp.path().display()
-            );
-            helpers::exit_process(1);
-        }
-
-        let mut paths = Vec::new();
-        let contents = t!(fs::read(stamp.path()), stamp.path());
-        // This is the method we use for extracting paths from the stamp file passed to us. See
-        // run_cargo for more information (in compile.rs).
-        for part in contents.split(|b| *b == 0) {
-            if part.is_empty() {
-                continue;
-            }
-            let dependency_type = match part[0] as char {
-                'h' => DependencyType::Host,
-                's' => DependencyType::TargetSelfContained,
-                't' => DependencyType::Target,
-                _ => unreachable!(),
-            };
-            let path = PathBuf::from(t!(str::from_utf8(&part[1..])));
-            paths.push((path, dependency_type));
-        }
-        paths
-    }
-
-    /// Copies a file from `src` to `dst`.
-    ///
-    /// If `src` is a symlink, `src` will be resolved to the actual path
-    /// and copied to `dst` instead of the symlink itself.
-    #[track_caller]
-    pub fn resolve_symlink_and_copy(&self, src: &Path, dst: &Path) {
-        self.copy_link_internal(src, dst, true);
-    }
-
-    /// Links a file from `src` to `dst`.
-    /// Attempts to use hard links if possible, falling back to copying.
-    /// You can neither rely on this being a copy nor it being a link,
-    /// so do not write to dst.
-    #[track_caller]
-    pub fn copy_link(&self, src: &Path, dst: &Path, file_type: FileType) {
-        self.copy_link_internal(src, dst, false);
-
-        if file_type.could_have_split_debuginfo()
-            && let Some(dbg_file) = split_debuginfo(src)
-        {
-            self.copy_link_internal(
-                &dbg_file,
-                &dst.with_extension(dbg_file.extension().unwrap()),
-                false,
-            );
-        }
-    }
-
-    #[track_caller]
-    fn copy_link_internal(&self, src: &Path, dst: &Path, dereference_symlinks: bool) {
-        if self.config.dry_run() {
-            return;
-        }
-        if src == dst {
-            return;
-        }
-
-        #[cfg(feature = "tracing")]
-        let _span = trace_io!("file-copy-link", ?src, ?dst);
-
-        if let Err(e) = fs::remove_file(dst)
-            && cfg!(windows)
-            && e.kind() != io::ErrorKind::NotFound
-        {
-            // workaround for https://github.com/rust-lang/rust/issues/127126
-            // if removing the file fails, attempt to rename it instead.
-            let now = t!(SystemTime::now().duration_since(SystemTime::UNIX_EPOCH));
-            let _ = fs::rename(dst, format!("{}-{}", dst.display(), now.as_nanos()));
-        }
-        let mut metadata = t!(src.symlink_metadata(), format!("src = {}", src.display()));
-        let mut src = src.to_path_buf();
-        if metadata.file_type().is_symlink() {
-            if dereference_symlinks {
-                src = t!(fs::canonicalize(src));
-                metadata = t!(fs::metadata(&src), format!("target = {}", src.display()));
-            } else {
-                let link = t!(fs::read_link(src));
-                t!(self.symlink_file(link, dst));
-                return;
-            }
-        }
-        if let Ok(()) = fs::hard_link(&src, dst) {
-            // Attempt to "easy copy" by creating a hard link (symlinks are privileged on windows),
-            // but if that fails just fall back to a slow `copy` operation.
-        } else {
-            if let Err(e) = fs::copy(&src, dst) {
-                panic!("failed to copy `{}` to `{}`: {}", src.display(), dst.display(), e)
-            }
-            t!(fs::set_permissions(dst, metadata.permissions()));
-
-            // Restore file times because changing permissions on e.g. Linux using `chmod` can cause
-            // file access time to change.
-            let file_times = fs::FileTimes::new()
-                .set_accessed(t!(metadata.accessed()))
-                .set_modified(t!(metadata.modified()));
-            t!(set_file_times(dst, file_times));
-        }
-    }
-
-    /// Links the `src` directory recursively to `dst`. Both are assumed to exist
-    /// when this function is called.
-    /// Will attempt to use hard links if possible and fall back to copying.
-    #[track_caller]
-    pub fn cp_link_r(&self, src: &Path, dst: &Path) {
-        if self.config.dry_run() {
-            return;
-        }
-        for f in self.read_dir(src) {
-            let path = f.path();
-            let name = path.file_name().unwrap();
-            let dst = dst.join(name);
-            if t!(f.file_type()).is_dir() {
-                t!(fs::create_dir_all(&dst));
-                self.cp_link_r(&path, &dst);
-            } else {
-                self.copy_link(&path, &dst, FileType::Regular);
-            }
-        }
-    }
-
-    /// Copies the `src` directory recursively to `dst`. Both are assumed to exist
-    /// when this function is called.
-    /// Will attempt to use hard links if possible and fall back to copying.
-    /// Unwanted files or directories can be skipped
-    /// by returning `false` from the filter function.
-    #[track_caller]
-    pub fn cp_link_filtered(&self, src: &Path, dst: &Path, filter: &dyn Fn(&Path) -> bool) {
-        // Immediately recurse with an empty relative path
-        self.cp_link_filtered_recurse(src, dst, Path::new(""), filter)
-    }
-
-    // Inner function does the actual work
-    #[track_caller]
-    fn cp_link_filtered_recurse(
-        &self,
-        src: &Path,
-        dst: &Path,
-        relative: &Path,
-        filter: &dyn Fn(&Path) -> bool,
-    ) {
-        for f in self.read_dir(src) {
-            let path = f.path();
-            let name = path.file_name().unwrap();
-            let dst = dst.join(name);
-            let relative = relative.join(name);
-            // Only copy file or directory if the filter function returns true
-            if filter(&relative) {
-                if t!(f.file_type()).is_dir() {
-                    let _ = fs::remove_dir_all(&dst);
-                    self.create_dir(&dst);
-                    self.cp_link_filtered_recurse(&path, &dst, &relative, filter);
-                } else {
-                    self.copy_link(&path, &dst, FileType::Regular);
-                }
-            }
-        }
-    }
-
-    fn copy_link_to_folder(&self, src: &Path, dest_folder: &Path) {
-        let file_name = src.file_name().unwrap();
-        let dest = dest_folder.join(file_name);
-        self.copy_link(src, &dest, FileType::Regular);
-    }
-
-    fn install(&self, src: &Path, dstdir: &Path, file_type: FileType) {
-        if self.config.dry_run() {
-            return;
-        }
-        let dst = dstdir.join(src.file_name().unwrap());
-
-        #[cfg(feature = "tracing")]
-        let _span = trace_io!("install", ?src, ?dst);
-
-        t!(fs::create_dir_all(dstdir));
-        if !src.exists() {
-            panic!("ERROR: File \"{}\" not found!", src.display());
-        }
-
-        self.copy_link_internal(src, &dst, true);
-        chmod(&dst, file_type.perms());
-
-        // If this file can have debuginfo, look for split debuginfo and install it too.
-        if file_type.could_have_split_debuginfo()
-            && let Some(dbg_file) = split_debuginfo(src)
-        {
-            self.install(&dbg_file, dstdir, FileType::Regular);
-        }
-    }
-
-    fn read(&self, path: &Path) -> String {
-        if self.config.dry_run() {
-            return String::new();
-        }
-        t!(fs::read_to_string(path))
-    }
-
-    #[track_caller]
-    fn create_dir(&self, dir: &Path) {
-        if self.config.dry_run() {
-            return;
-        }
-
-        #[cfg(feature = "tracing")]
-        let _span = trace_io!("dir-create", ?dir);
-
-        t!(fs::create_dir_all(dir))
-    }
-
-    fn remove_dir(&self, dir: &Path) {
-        if self.config.dry_run() {
-            return;
-        }
-
-        #[cfg(feature = "tracing")]
-        let _span = trace_io!("dir-remove", ?dir);
-
-        t!(fs::remove_dir_all(dir))
-    }
-
-    /// Make sure that `dir` will be an empty existing directory after this function ends.
-    /// If it existed before, it will be first deleted.
-    fn clear_dir(&self, dir: &Path) {
-        if self.config.dry_run() {
-            return;
-        }
-
-        #[cfg(feature = "tracing")]
-        let _span = trace_io!("dir-clear", ?dir);
-
-        let _ = std::fs::remove_dir_all(dir);
-        self.create_dir(dir);
-    }
-
-    fn read_dir(&self, dir: &Path) -> impl Iterator<Item = fs::DirEntry> {
-        let iter = match fs::read_dir(dir) {
-            Ok(v) => v,
-            Err(_) if self.config.dry_run() => return vec![].into_iter(),
-            Err(err) => panic!("could not read dir {dir:?}: {err:?}"),
-        };
-        iter.map(|e| t!(e)).collect::<Vec<_>>().into_iter()
-    }
-
-    fn symlink_file<P: AsRef<Path>, Q: AsRef<Path>>(&self, src: P, link: Q) -> io::Result<()> {
-        #[cfg(unix)]
-        use std::os::unix::fs::symlink as symlink_file;
-        #[cfg(windows)]
-        use std::os::windows::fs::symlink_file;
-        if !self.config.dry_run() { symlink_file(src.as_ref(), link.as_ref()) } else { Ok(()) }
-    }
-
-    /// Returns if config.ninja is enabled, and checks for ninja existence,
-    /// exiting with a nicer error message if not.
-    fn ninja(&self) -> bool {
-        let mut cmd_finder = crate::core::sanity::Finder::new();
-
-        if self.config.ninja_in_file {
-            // Some Linux distros rename `ninja` to `ninja-build`.
-            // CMake can work with either binary name.
-            if cmd_finder.maybe_have("ninja-build").is_none()
-                && cmd_finder.maybe_have("ninja").is_none()
-            {
-                eprintln!(
-                    "
-Couldn't find required command: ninja (or ninja-build)
-
-You should install ninja as described at
-<https://github.com/ninja-build/ninja/wiki/Pre-built-Ninja-packages>,
-or set `ninja = false` in the `[llvm]` section of `bootstrap.toml`.
-Alternatively, set `download-ci-llvm = true` in that `[llvm]` section
-to download LLVM rather than building it.
-"
-                );
-                helpers::exit_process(1);
-            }
-        }
-
-        // If ninja isn't enabled but we're building for MSVC then we try
-        // doubly hard to enable it. It was realized in #43767 that the msbuild
-        // CMake generator for MSVC doesn't respect configuration options like
-        // disabling LLVM assertions, which can often be quite important!
-        //
-        // In these cases we automatically enable Ninja if we find it in the
-        // environment.
-        if !self.config.ninja_in_file
-            && self.config.host_target.is_msvc()
-            && cmd_finder.maybe_have("ninja").is_some()
-        {
-            return true;
-        }
-
-        self.config.ninja_in_file
-    }
-
-    pub fn colored_stdout<R, F: FnOnce(&mut dyn WriteColor) -> R>(&self, f: F) -> R {
-        self.colored_stream_inner(StandardStream::stdout, self.config.stdout_is_tty, f)
-    }
-
-    pub fn colored_stderr<R, F: FnOnce(&mut dyn WriteColor) -> R>(&self, f: F) -> R {
-        self.colored_stream_inner(StandardStream::stderr, self.config.stderr_is_tty, f)
-    }
-
-    fn colored_stream_inner<R, F, C>(&self, constructor: C, is_tty: bool, f: F) -> R
-    where
-        C: Fn(ColorChoice) -> StandardStream,
-        F: FnOnce(&mut dyn WriteColor) -> R,
-    {
-        let choice = match self.config.color {
-            flags::Color::Always => ColorChoice::Always,
-            flags::Color::Never => ColorChoice::Never,
-            flags::Color::Auto if !is_tty => ColorChoice::Never,
-            flags::Color::Auto => ColorChoice::Auto,
-        };
-        let mut stream = constructor(choice);
-        let result = f(&mut stream);
-        stream.reset().unwrap();
-        result
-    }
-
-    pub fn report_summary(&self, path: &Path, start_time: Instant) {
-        self.config.exec_ctx.profiler().report_summary(path, start_time);
-    }
-
-    #[cfg(feature = "tracing")]
-    pub fn report_step_graph(self, directory: &Path) {
-        self.step_graph.into_inner().store_to_dot_files(directory);
-    }
-}
-
-impl AsRef<ExecutionContext> for Build {
-    fn as_ref(&self) -> &ExecutionContext {
-        &self.config.exec_ctx
-    }
-}
-
-#[cfg(unix)]
-fn chmod(path: &Path, perms: u32) {
-    use std::os::unix::fs::*;
-    t!(fs::set_permissions(path, fs::Permissions::from_mode(perms)));
-}
-#[cfg(windows)]
-fn chmod(_path: &Path, _perms: u32) {}
diff --git a/src/bootstrap/src/utils/build_stamp.rs b/src/bootstrap/src/utils/build_stamp.rs
index d27d5fa2cf420..36a3d0772e5ad 100644
--- a/src/bootstrap/src/utils/build_stamp.rs
+++ b/src/bootstrap/src/utils/build_stamp.rs
@@ -7,11 +7,11 @@ use std::{fs, io};
 
 use sha2::digest::Digest;
 
-use crate::Mode;
 use crate::core::backend::CodegenBackendKind;
 use crate::core::builder::Builder;
 use crate::core::compiler::Compiler;
 use crate::core::config::TargetSelection;
+use crate::core::session::Mode;
 use crate::utils::helpers::{self, hex_encode, mtime, t};
 
 #[cfg(test)]
diff --git a/src/bootstrap/src/utils/cc_detect.rs b/src/bootstrap/src/utils/cc_detect.rs
index 977b4a31eadc4..e753ee71683fd 100644
--- a/src/bootstrap/src/utils/cc_detect.rs
+++ b/src/bootstrap/src/utils/cc_detect.rs
@@ -27,8 +27,8 @@ use std::path::{Path, PathBuf};
 
 use crate::core::config::flags::Subcommand;
 use crate::core::config::{CompressDebuginfo, TargetSelection};
+use crate::core::session::{Build, CLang, GitRepo};
 use crate::utils::exec::{BootstrapCommand, command};
-use crate::{Build, CLang, GitRepo};
 
 /// Creates and configures a new [`cc::Build`] instance for the given target.
 fn new_cc_build(build: &Build, target: TargetSelection) -> cc::Build {
diff --git a/src/bootstrap/src/utils/cc_detect/tests.rs b/src/bootstrap/src/utils/cc_detect/tests.rs
index a2f35e6a1030d..716407cb0cb1c 100644
--- a/src/bootstrap/src/utils/cc_detect/tests.rs
+++ b/src/bootstrap/src/utils/cc_detect/tests.rs
@@ -2,8 +2,8 @@ use std::iter;
 use std::path::PathBuf;
 
 use super::*;
-use crate::Build;
 use crate::core::config::{Target, TargetSelection};
+use crate::core::session::Build;
 use crate::utils::tests::TestCtx;
 
 #[test]
diff --git a/src/bootstrap/src/utils/channel.rs b/src/bootstrap/src/utils/channel.rs
index 21b4257e54d0b..ebb40edf9b262 100644
--- a/src/bootstrap/src/utils/channel.rs
+++ b/src/bootstrap/src/utils/channel.rs
@@ -10,7 +10,7 @@ use std::path::Path;
 
 use super::exec::ExecutionContext;
 use super::helpers;
-use crate::Build;
+use crate::core::session::Build;
 use crate::utils::helpers::t;
 
 #[derive(Clone, Default)]
diff --git a/src/bootstrap/src/utils/job.rs b/src/bootstrap/src/utils/job.rs
index 887deb41ca8bc..942ac6c80e4ee 100644
--- a/src/bootstrap/src/utils/job.rs
+++ b/src/bootstrap/src/utils/job.rs
@@ -1,11 +1,13 @@
 #[cfg(windows)]
 pub use for_windows::*;
 
+use crate::core::session::Build;
+
 #[cfg(any(target_os = "haiku", target_os = "hermit", not(any(unix, windows))))]
-pub unsafe fn setup(_build: &mut crate::Build) {}
+pub unsafe fn setup(_build: &mut Build) {}
 
 #[cfg(all(unix, not(target_os = "haiku")))]
-pub unsafe fn setup(build: &mut crate::Build) {
+pub unsafe fn setup(build: &mut Build) {
     if build.config.low_priority {
         unsafe {
             libc::setpriority(libc::PRIO_PGRP as _, 0, 10);
@@ -58,9 +60,7 @@ mod for_windows {
     use windows::Win32::System::Threading::{BELOW_NORMAL_PRIORITY_CLASS, GetCurrentProcess};
     use windows::core::PCWSTR;
 
-    use crate::Build;
-
-    pub unsafe fn setup(build: &mut Build) {
+    pub unsafe fn setup(build: &mut super::Build) {
         // SAFETY: pretty much everything below is unsafe
         unsafe {
             // Enable the Windows Error Reporting dialog which msys disables,
diff --git a/src/bootstrap/src/utils/metrics.rs b/src/bootstrap/src/utils/metrics.rs
index e685c64733c66..a309b1d53b8e9 100644
--- a/src/bootstrap/src/utils/metrics.rs
+++ b/src/bootstrap/src/utils/metrics.rs
@@ -16,8 +16,8 @@ use build_helper::metrics::{
 };
 use sysinfo::{CpuRefreshKind, RefreshKind, System};
 
-use crate::Build;
 use crate::core::builder::{Builder, Step};
+use crate::core::session::Build;
 use crate::utils::helpers::t;
 
 // Update this number whenever a breaking change is made to the build metrics.
diff --git a/src/bootstrap/src/utils/tarball.rs b/src/bootstrap/src/utils/tarball.rs
index 41ad6b022ac18..3ba7dbdb984c8 100644
--- a/src/bootstrap/src/utils/tarball.rs
+++ b/src/bootstrap/src/utils/tarball.rs
@@ -7,10 +7,10 @@
 
 use std::path::{Path, PathBuf};
 
-use crate::FileType;
 use crate::core::build_steps::dist::distdir;
 use crate::core::builder::{Builder, Kind};
 use crate::core::config::BUILDER_CONFIG_FILENAME;
+use crate::core::session::FileType;
 use crate::utils::channel;
 use crate::utils::exec::BootstrapCommand;
 use crate::utils::helpers::{self, move_file, t};
diff --git a/src/ci/citool/src/jobs.rs b/src/ci/citool/src/jobs.rs
index 8b4f66c85761a..9800f14d8fa39 100644
--- a/src/ci/citool/src/jobs.rs
+++ b/src/ci/citool/src/jobs.rs
@@ -44,7 +44,7 @@ impl Job {
     }
 
     fn is_linux(&self) -> bool {
-        self.os.contains("ubuntu")
+        self.os.contains("ubuntu") || self.os.contains("linux")
     }
 }
 
@@ -414,7 +414,10 @@ pub fn find_linux_job<'a>(jobs: &'a [Job], name: &str) -> anyhow::Result<&'a Job
         ));
     };
     if !job.is_linux() {
-        return Err(anyhow::anyhow!("Only Linux jobs can be executed locally"));
+        return Err(anyhow::anyhow!(
+            "Only Linux jobs can be executed locally, os `{}` is not linux",
+            job.os
+        ));
     }
 
     Ok(job)
diff --git a/src/tools/rustfmt/src/macros.rs b/src/tools/rustfmt/src/macros.rs
index e4c05d58004a7..8bfd99f2f7c9f 100644
--- a/src/tools/rustfmt/src/macros.rs
+++ b/src/tools/rustfmt/src/macros.rs
@@ -454,7 +454,7 @@ pub(crate) fn rewrite_macro_def(
     };
 
     let mut header = if def.macro_rules {
-        let pos = context.snippet_provider.span_after(span, "macro_rules!");
+        let pos = context.snippet_provider.span_after(span, "!");
         vec![HeaderPart::new("macro_rules!", span.with_hi(pos))]
     } else {
         let macro_lo = context.snippet_provider.span_before(span, "macro");
diff --git a/tests/codegen-llvm/gpu_offload/control_flow.rs b/tests/codegen-llvm/gpu_offload/control_flow.rs
index da997de53a428..8cafeda3395ce 100644
--- a/tests/codegen-llvm/gpu_offload/control_flow.rs
+++ b/tests/codegen-llvm/gpu_offload/control_flow.rs
@@ -6,8 +6,8 @@
 // contains control flow.
 
 #![feature(abi_gpu_kernel)]
+#![feature(gpu_offload)]
 #![feature(rustc_attrs)]
-#![feature(core_intrinsics)]
 #![no_main]
 
 // CHECK: @.offload_sizes.[[K:[^ ]*foo]] = private unnamed_addr constant
@@ -28,13 +28,12 @@ unsafe fn main() {
     let A = [1.0, 1.0, 1.0, 1.0, 1.0, 1.0];
 
     for i in 0..100 {
-        core::intrinsics::offload::<_, _, ()>(
-            foo,
-            [256, 1, 1],
-            [32, 1, 1],
-            0,
-            (A.as_ptr() as *const [f32; 6],),
-        );
+        core::offload::offload! {
+            kernel = foo,
+            workgroup_dim = [256, 1, 1],
+            thread_dim = [32, 1, 1],
+            args = (A.as_ptr() as *const [f32; 6],),
+        }
     }
 }
 
diff --git a/tests/codegen-llvm/gpu_offload/device_check.rs b/tests/codegen-llvm/gpu_offload/device_check.rs
new file mode 100644
index 0000000000000..4eaa324a662a4
--- /dev/null
+++ b/tests/codegen-llvm/gpu_offload/device_check.rs
@@ -0,0 +1,30 @@
+//@ compile-flags: -Zoffload=Test -Zunstable-options -C opt-level=0 -Clto=fat
+//@ no-prefer-dynamic
+//@ needs-offload
+
+// This test verifies that selecting an unavailable `device` in the `offload` macro panics.
+
+#![feature(gpu_offload)]
+#![no_main]
+
+#[unsafe(no_mangle)]
+fn main() {
+    core::offload::offload! {
+        kernel = kernel,
+        device = 99,
+        args = (),
+    }
+}
+
+#[unsafe(no_mangle)]
+fn kernel() {}
+
+// CHECK-LABEL: define{{( dso_local)?}} void @main()
+// CHECK: store i32 99, ptr %device, align 4
+// CHECK-NEXT: %{{[0-9_]+}} = call i32 @omp_get_num_devices()
+// CHECK-NEXT: %{{[0-9_]+}} = load i32, ptr %device, align 4
+// CHECK-NEXT: %{{[0-9_]+}} = icmp slt i32 %{{[0-9_]+}}, %{{[0-9_]+}}
+// CHECK-NEXT: br i1 %{{[0-9_]+}}, label %bb{{[0-9]+}}, label %bb{{[0-9]+}}
+// CHECK: call void @{{.*}}panic_fmt
+// CHECK: unreachable
+// CHECK: call i32 @__tgt_target_kernel
diff --git a/tests/codegen-llvm/gpu_offload/gpu_host.rs b/tests/codegen-llvm/gpu_offload/gpu_host.rs
index 2bfaf89b45590..45fcf6cf5c3ce 100644
--- a/tests/codegen-llvm/gpu_offload/gpu_host.rs
+++ b/tests/codegen-llvm/gpu_offload/gpu_host.rs
@@ -7,8 +7,8 @@
 // Better documentation to what each global or variable means is available in the gpu offload code,
 // or the LLVM offload documentation.
 
+#![feature(gpu_offload)]
 #![feature(rustc_attrs)]
-#![feature(core_intrinsics)]
 #![no_main]
 
 #[unsafe(no_mangle)]
@@ -21,7 +21,12 @@ fn main() {
 }
 
 pub fn kernel_1(x: &mut [f32; 256], y: &[f32; 256]) {
-    core::intrinsics::offload(_kernel_1, [256, 1, 1], [32, 1, 1], 0, (x, y))
+    core::offload::offload! {
+        kernel = _kernel_1,
+        workgroup_dim = [256, 1, 1],
+        thread_dim = [32, 1, 1],
+        args = (x, y),
+    }
 }
 
 #[inline(never)]
@@ -78,8 +83,10 @@ pub fn _kernel_1(x: &mut [f32; 256], y: &[f32; 256]) {
 // CHECK-NEXT:   [[P32:%[^ ]+]] = getelementptr inbounds nuw i8, ptr %kernel_args, i64 32
 // CHECK-NEXT:   store ptr @.offload_maptypes.[[K]].kernel, ptr [[P32]], align 8
 // CHECK-NEXT:   [[P40:%[^ ]+]] = getelementptr inbounds nuw i8, ptr %kernel_args, i64 40
+// CHECK-NEXT:   [[P64:%[^ ]+]] = getelementptr inbounds nuw i8, ptr %kernel_args, i64 64
+// CHECK-NEXT:   call void @llvm.memset.p0.i64(ptr noundef nonnull align 8 dereferenceable(24) [[P40]], i8 0, i64 24, i1 false)
+// CHECK-NEXT:   store i64 64, ptr [[P64]], align 8
 // CHECK-NEXT:   [[P72:%[^ ]+]] = getelementptr inbounds nuw i8, ptr %kernel_args, i64 72
-// CHECK-NEXT:   call void @llvm.memset.p0.i64(ptr noundef nonnull align 8 dereferenceable(32) [[P40]], i8 0, i64 32, i1 false)
 // CHECK-NEXT:   store <4 x i32> <i32 256, i32 1, i32 1, i32 32>, ptr [[P72]], align 8
 // CHECK-NEXT:   [[P88:%[^ ]+]] = getelementptr inbounds nuw i8, ptr %kernel_args, i64 88
 // CHECK-NEXT:   store i32 1, ptr [[P88]], align 8
@@ -95,17 +102,17 @@ pub fn _kernel_1(x: &mut [f32; 256], y: &[f32; 256]) {
 // CHECK: declare void @__tgt_register_lib(ptr) local_unnamed_addr
 // CHECK: declare void @__tgt_unregister_lib(ptr) local_unnamed_addr
 
-// CHECK-LABEL: define internal void @.omp_offloading.descriptor_reg() section ".text.startup" {
+// CHECK-LABEL: define internal void @.omp_offloading.descriptor_reg() section ".text.startup"
 // CHECK-NEXT: entry:
-// CHECK-NEXT:   call void @__tgt_register_lib(ptr nonnull @.omp_offloading.descriptor)
-// CHECK-NEXT:   call void @__tgt_init_all_rtls()
+// CHECK-NEXT:   {{tail }}call void @__tgt_register_lib(ptr nonnull @.omp_offloading.descriptor)
+// CHECK-NEXT:   {{tail }}call void @__tgt_init_all_rtls()
 // CHECK-NEXT:   %0 = {{tail }}call i32 @atexit(ptr nonnull @.omp_offloading.descriptor_unreg)
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }
 
-// CHECK-LABEL: define internal void @.omp_offloading.descriptor_unreg() section ".text.startup" {
+// CHECK-LABEL: define internal void @.omp_offloading.descriptor_unreg() section ".text.startup"
 // CHECK-NEXT: entry:
-// CHECK-NEXT:   call void @__tgt_unregister_lib(ptr nonnull @.omp_offloading.descriptor)
+// CHECK-NEXT:   {{tail }}call void @__tgt_unregister_lib(ptr nonnull @.omp_offloading.descriptor)
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }
 
diff --git a/tests/codegen-llvm/gpu_offload/scalar_host.rs b/tests/codegen-llvm/gpu_offload/scalar_host.rs
index 66c910c439e46..807d08ddf1893 100644
--- a/tests/codegen-llvm/gpu_offload/scalar_host.rs
+++ b/tests/codegen-llvm/gpu_offload/scalar_host.rs
@@ -6,8 +6,8 @@
 // the kernel as i64
 
 #![feature(abi_gpu_kernel)]
+#![feature(gpu_offload)]
 #![feature(rustc_attrs)]
-#![feature(core_intrinsics)]
 #![no_main]
 
 // CHECK: define{{( dso_local)?}} void @main()
@@ -28,7 +28,10 @@ fn main() {
     let mut x = 0.0f32;
     let k = core::hint::black_box(42.0f32);
 
-    core::intrinsics::offload::<_, _, ()>(foo, [1, 1, 1], [1, 1, 1], 0, (&mut x as *mut f32, k));
+    core::offload::offload! {
+        kernel = foo,
+        args = (&mut x as *mut f32, k),
+    }
 }
 
 unsafe extern "C" {
diff --git a/tests/codegen-llvm/gpu_offload/slice_device.rs b/tests/codegen-llvm/gpu_offload/slice_device.rs
index 1abe04f8cc429..6e900c21ca7cb 100644
--- a/tests/codegen-llvm/gpu_offload/slice_device.rs
+++ b/tests/codegen-llvm/gpu_offload/slice_device.rs
@@ -15,7 +15,7 @@ extern crate minicore;
 // CHECK: ; Function Attrs
 // nvptx-NEXT: define ptx_kernel void @foo
 // amdgpu-NEXT: define amdgpu_kernel void @foo
-// CHECK-SAME: ptr readnone captures(none) %dyn_ptr
+// CHECK-SAME: ptr nofree readnone captures(none) %dyn_ptr
 // nvptx-SAME: [2 x i64] %0
 // amdgpu-SAME: ptr noalias {{.*}} %0, i64 {{.*}} %1
 // CHECK-NEXT: entry:
diff --git a/tests/codegen-llvm/gpu_offload/slice_host.rs b/tests/codegen-llvm/gpu_offload/slice_host.rs
index dfc7ec545630c..ad47d2e76360a 100644
--- a/tests/codegen-llvm/gpu_offload/slice_host.rs
+++ b/tests/codegen-llvm/gpu_offload/slice_host.rs
@@ -5,8 +5,8 @@
 // This test verifies that offload is properly handling slices passing them properly to the device
 
 #![feature(abi_gpu_kernel)]
+#![feature(gpu_offload)]
 #![feature(rustc_attrs)]
-#![feature(core_intrinsics)]
 #![no_main]
 
 // CHECK: @anon.[[ID:.*]].0 = private unnamed_addr constant [23 x i8] c";unknown;unknown;0;0;;\00", align 1
@@ -27,7 +27,10 @@
 #[unsafe(no_mangle)]
 fn main() {
     let mut x = [0.0f32, 0.0, 0.0, 0.0];
-    core::intrinsics::offload::<_, _, ()>(foo, [1, 1, 1], [1, 1, 1], 0, ((&mut x) as &mut [f32],));
+    core::offload::offload! {
+        kernel = foo,
+        args = ((&mut x) as &mut [f32],),
+    }
 }
 
 unsafe extern "C" {
diff --git a/tests/run-make/offload-generic-manifest/generic.rs b/tests/run-make/offload-generic-manifest/generic.rs
index eb356ad05c574..a6b8a7368858d 100644
--- a/tests/run-make/offload-generic-manifest/generic.rs
+++ b/tests/run-make/offload-generic-manifest/generic.rs
@@ -1,4 +1,4 @@
-#![feature(core_intrinsics, rustc_attrs)]
+#![feature(gpu_offload, rustc_attrs)]
 #![allow(internal_features)]
 #![cfg_attr(device, no_main)]
 
@@ -7,6 +7,12 @@ fn kernel<T: Copy>(x: T) {}
 
 #[cfg(not(device))]
 fn main() {
-    core::intrinsics::offload::<_, _, ()>(kernel::<f32>, [1, 1, 1], [1, 1, 1], 0, (0.0f32,));
-    core::intrinsics::offload::<_, _, ()>(kernel::<i32>, [1, 1, 1], [1, 1, 1], 0, (0i32,));
+    core::offload::offload! {
+        kernel = kernel::<f32>,
+        args = (0.0f32,),
+    }
+    core::offload::offload! {
+        kernel = kernel::<i32>,
+        args = (0i32,),
+    }
 }
diff --git a/tests/ui-fulldeps/lto-with-rustc-private.rs b/tests/ui-fulldeps/lto-with-rustc-private.rs
new file mode 100644
index 0000000000000..7695d5b6ea1cc
--- /dev/null
+++ b/tests/ui-fulldeps/lto-with-rustc-private.rs
@@ -0,0 +1,14 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/45689>.
+
+//@ build-fail
+//@ compile-flags: -Clto
+//@ normalize-stderr: "error: crate .* required.*\n(   .*\n)*\n" -> ""
+//@ normalize-stderr: "aborting due to [0-9]+" -> "aborting due to NUMBER"
+//@ dont-require-annotations: ERROR
+
+#![feature(rustc_private)]
+
+extern crate rustc_errors;
+//~? ERROR crate `rustc_errors` required to be available in rlib format
+
+fn main() {}
diff --git a/tests/ui-fulldeps/lto-with-rustc-private.stderr b/tests/ui-fulldeps/lto-with-rustc-private.stderr
new file mode 100644
index 0000000000000..58577ffffb3f6
--- /dev/null
+++ b/tests/ui-fulldeps/lto-with-rustc-private.stderr
@@ -0,0 +1,2 @@
+error: aborting due to NUMBER previous errors
+
diff --git a/tests/ui/diagnostic-width/elided-span-with-hard-tabs.rs b/tests/ui/diagnostic-width/elided-span-with-hard-tabs.rs
new file mode 100644
index 0000000000000..d455da13fef83
--- /dev/null
+++ b/tests/ui/diagnostic-width/elided-span-with-hard-tabs.rs
@@ -0,0 +1,11 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/146398>.
+
+// The panic happens while the JSON emitter fills in its `rendered` field, which is the
+// path `cargo` takes, so this has to be checked with the default JSON error format.
+//@ compile-flags: --diagnostic-width=30
+// ignore-tidy-file-tab
+
+fn main() {
+    let _: &[u8] = [0,												0];
+    //~^ ERROR mismatched types
+}
diff --git a/tests/ui/diagnostic-width/elided-span-with-hard-tabs.stderr b/tests/ui/diagnostic-width/elided-span-with-hard-tabs.stderr
new file mode 100644
index 0000000000000..6415675e5a69d
--- /dev/null
+++ b/tests/ui/diagnostic-width/elided-span-with-hard-tabs.stderr
@@ -0,0 +1,16 @@
+error[E0308]: mismatched types
+  --> $DIR/elided-span-with-hard-tabs.rs:9:20
+   |
+LL | ..._: &[u8] = [0,     ...      0];
+   |       -----   ^^^^^^^^...^^^^^^^^ expected `&[u8]`, found `[{integer}; 2]`
+   |       |
+   |       expected due to this
+   |
+help: consider borrowing here
+   |
+LL |     let _: &[u8] = &[0,                                                0];
+   |                    +
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/impl-trait/nested-rpit-not-iterator-ice-159559.rs b/tests/ui/impl-trait/nested-rpit-not-iterator-ice-159559.rs
new file mode 100644
index 0000000000000..03842bc36db7a
--- /dev/null
+++ b/tests/ui/impl-trait/nested-rpit-not-iterator-ice-159559.rs
@@ -0,0 +1,19 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/159559>.
+//! Reporting the `E0277` for the unsatisfied `IntoIterator` bound on the
+//! nested opaque type used to ICE ("Normalizing ... without wrapping in a
+//! `Binder`") in the RPIT method-chain suggestion when the return type
+//! captures a lifetime.
+
+trait Cap<'a> {}
+
+impl<T> Cap<'_> for T {}
+
+fn fail_late_bound<'a>(
+    a: &u8,
+    _: &'a u8,
+) -> impl IntoIterator<Item = impl Cap<'a> + IntoIterator<Item = impl Cap<'a>>> {
+    //~^ ERROR `&u8` is not an iterator
+    [a]
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/nested-rpit-not-iterator-ice-159559.stderr b/tests/ui/impl-trait/nested-rpit-not-iterator-ice-159559.stderr
new file mode 100644
index 0000000000000..4ba03ed69999c
--- /dev/null
+++ b/tests/ui/impl-trait/nested-rpit-not-iterator-ice-159559.stderr
@@ -0,0 +1,12 @@
+error[E0277]: `&u8` is not an iterator
+  --> $DIR/nested-rpit-not-iterator-ice-159559.rs:14:31
+   |
+LL | ) -> impl IntoIterator<Item = impl Cap<'a> + IntoIterator<Item = impl Cap<'a>>> {
+   |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `&u8` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `&u8`
+   = note: required for `&u8` to implement `IntoIterator`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/macros/auxiliary/nested-macro-rules-definition.rs b/tests/ui/macros/auxiliary/nested-macro-rules-definition.rs
new file mode 100644
index 0000000000000..cb980fd3d9274
--- /dev/null
+++ b/tests/ui/macros/auxiliary/nested-macro-rules-definition.rs
@@ -0,0 +1,15 @@
+pub struct ProjectileCreated;
+pub struct NotificationChannel<E>(std::marker::PhantomData<E>);
+
+// The inner `macro_rules!` is what later reports a span from this crate while the
+// diagnostic is being rendered against the downstream crate's source.
+macro_rules! define_trigger_system {
+    ($(( $field:ident, $ty:ident, $channel:ident )),* $(,)?) => {
+        #[macro_export]
+        macro_rules! all_trigger_fields {
+            ($submacro:ident) => { $submacro!($( ( $field, $ty, $channel ) ),*) }
+        }
+    };
+}
+
+define_trigger_system!((projectile_created, ProjectileCreated, NotificationChannel),);
diff --git a/tests/ui/macros/cross-crate-nested-macro-rules-span.rs b/tests/ui/macros/cross-crate-nested-macro-rules-span.rs
new file mode 100644
index 0000000000000..9353398093ff8
--- /dev/null
+++ b/tests/ui/macros/cross-crate-nested-macro-rules-span.rs
@@ -0,0 +1,18 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/66805>.
+
+//@ aux-build: nested-macro-rules-definition.rs
+
+extern crate nested_macro_rules_definition;
+use nested_macro_rules_definition::*;
+
+macro_rules! make_event_subscription {
+    ($(( $field:ident, $ty:ident, $channel:ident )),*) => {
+        pub struct EventSubscription($($channel<nested_macro_rules_definition::$ty>::ReaderId),*);
+        //~^ ERROR ambiguous associated type
+    };
+}
+
+all_trigger_fields!(make_event_subscription);
+//~^ ERROR macros that expand to items must be delimited with braces or followed by a semicolon
+
+fn main() {}
diff --git a/tests/ui/macros/cross-crate-nested-macro-rules-span.stderr b/tests/ui/macros/cross-crate-nested-macro-rules-span.stderr
new file mode 100644
index 0000000000000..edf3d575b972d
--- /dev/null
+++ b/tests/ui/macros/cross-crate-nested-macro-rules-span.stderr
@@ -0,0 +1,27 @@
+error: macros that expand to items must be delimited with braces or followed by a semicolon
+  --> $DIR/cross-crate-nested-macro-rules-span.rs:15:1
+   |
+LL | all_trigger_fields!(make_event_subscription);
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this error originates in the macro `all_trigger_fields` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0223]: ambiguous associated type
+  --> $DIR/cross-crate-nested-macro-rules-span.rs:10:40
+   |
+LL |         pub struct EventSubscription($($channel<nested_macro_rules_definition::$ty>::ReaderId),*);
+   |                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | all_trigger_fields!(make_event_subscription);
+   | -------------------------------------------- in this macro invocation
+   |
+   = note: this error originates in the macro `make_event_subscription` which comes from the expansion of the macro `all_trigger_fields` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: if there were a trait named `Example` with associated type `ReaderId` implemented for `nested_macro_rules_definition::NotificationChannel<ProjectileCreated>`, you could use the fully-qualified path
+   |
+LL -         pub struct EventSubscription($($channel<nested_macro_rules_definition::$ty>::ReaderId),*);
+LL +         pub struct EventSubscription($(<nested_macro_rules_definition::NotificationChannel<ProjectileCreated> as Example>::ReaderId),*);
+   |
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0223`.
diff --git a/tests/ui/numbers-arithmetic/wrapping-ops-under-mir-opts.rs b/tests/ui/numbers-arithmetic/wrapping-ops-under-mir-opts.rs
new file mode 100644
index 0000000000000..ab0e48f51be6f
--- /dev/null
+++ b/tests/ui/numbers-arithmetic/wrapping-ops-under-mir-opts.rs
@@ -0,0 +1,11 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/82646>.
+
+//@ run-pass
+//@ compile-flags: -Zmir-opt-level=2 -Coverflow-checks=on
+
+fn main() {
+    assert_eq!(1_u32.wrapping_sub(2), u32::MAX);
+    assert_eq!(u32::MAX.wrapping_add(2), 1);
+    assert_eq!(i32::MIN.wrapping_sub(1), i32::MAX);
+    assert_eq!(2_u32.wrapping_mul(u32::MAX), u32::MAX - 1);
+}
diff --git a/tests/ui/offload/check_config.rs b/tests/ui/offload/check_config.rs
index ff145f420e482..63388ce69ba62 100644
--- a/tests/ui/offload/check_config.rs
+++ b/tests/ui/offload/check_config.rs
@@ -9,7 +9,7 @@
 //[fail]~? ERROR: using the offload feature requires -Z offload=<Device or Host=/absolute/path/to/device.bin>
 //[fail]~? ERROR: using the offload feature requires -C lto=fat
 
-#![feature(core_intrinsics)]
+#![feature(gpu_offload)]
 
 fn main() {
     let mut x = [3.0; 256];
@@ -17,7 +17,10 @@ fn main() {
 }
 
 fn kernel_1(x: &mut [f32; 256]) {
-    core::intrinsics::offload(_kernel_1, [1, 1, 1], [1, 1, 1], 0, (x,))
+    core::offload::offload! {
+        kernel = _kernel_1,
+        args = (x,),
+    }
 }
 
 fn _kernel_1(x: &mut [f32; 256]) {}
diff --git a/tests/ui/offload/duplicate_kernel.rs b/tests/ui/offload/duplicate_kernel.rs
index abde76137a37c..da667a0c0666a 100644
--- a/tests/ui/offload/duplicate_kernel.rs
+++ b/tests/ui/offload/duplicate_kernel.rs
@@ -18,5 +18,5 @@ fn kernel(_x: f32) {}
 
 fn main() {
     _RNvC19collision_kernels_a6kernel(0.0);
-    core::intrinsics::offload::<_, _, ()>(kernel, [1, 1, 1], [1, 1, 1], 0, (0.0f32,));
+    core::intrinsics::offload::<_, _, ()>(kernel, [1, 1, 1], [1, 1, 1], 0, -1, (0.0f32,));
 }
diff --git a/tests/ui/offload/non_tuple_args.rs b/tests/ui/offload/non_tuple_args.rs
index 0a07c99a26d34..14de21b2374a2 100644
--- a/tests/ui/offload/non_tuple_args.rs
+++ b/tests/ui/offload/non_tuple_args.rs
@@ -4,7 +4,7 @@
 
 fn main() {
     // args_ty is not a tuple
-    core::intrinsics::offload::<_, _, ()>(kernel_0, [1, 1, 1], [1, 1, 1], 0, 42);
+    core::intrinsics::offload::<_, _, ()>(kernel_0, [1, 1, 1], [1, 1, 1], 0, -1, 42);
     //~^ ERROR `{integer}` is not a tuple
 }
 
diff --git a/tests/ui/offload/non_tuple_args.stderr b/tests/ui/offload/non_tuple_args.stderr
index 8b59d6828c6f2..90b0f16bec53e 100644
--- a/tests/ui/offload/non_tuple_args.stderr
+++ b/tests/ui/offload/non_tuple_args.stderr
@@ -1,7 +1,7 @@
 error[E0277]: `{integer}` is not a tuple
   --> $DIR/non_tuple_args.rs:7:36
    |
-LL |     core::intrinsics::offload::<_, _, ()>(kernel_0, [1, 1, 1], [1, 1, 1], 0, 42);
+LL |     core::intrinsics::offload::<_, _, ()>(kernel_0, [1, 1, 1], [1, 1, 1], 0, -1, 42);
    |                                    ^ the nightly-only, unstable trait `std::marker::Tuple` is not implemented for `{integer}`
    |
 note: required by a bound in `offload`
diff --git a/tests/ui/offload/offload_macro.rs b/tests/ui/offload/offload_macro.rs
index 468820f08c291..4480f7dd9c80b 100644
--- a/tests/ui/offload/offload_macro.rs
+++ b/tests/ui/offload/offload_macro.rs
@@ -26,4 +26,7 @@ fn main() {
 
     core::offload::offload! { kernel = kernel, args = (), dyn_cache = 0, dyn_cache = 8 }
     //~^ ERROR duplicate field `dyn_cache`
+
+    core::offload::offload! { kernel = kernel, args = (), device = 0, device = 1 }
+    //~^ ERROR duplicate field `device`
 }
diff --git a/tests/ui/offload/offload_macro.stderr b/tests/ui/offload/offload_macro.stderr
index cd85afeab373e..e2517a2f8cca1 100644
--- a/tests/ui/offload/offload_macro.stderr
+++ b/tests/ui/offload/offload_macro.stderr
@@ -62,5 +62,13 @@ LL |     core::offload::offload! { kernel = kernel, args = (), dyn_cache = 0, dy
    |
    = note: this error originates in the macro `$crate::offload` which comes from the expansion of the macro `core::offload::offload` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 8 previous errors
+error: duplicate field `device`
+  --> $DIR/offload_macro.rs:30:5
+   |
+LL |     core::offload::offload! { kernel = kernel, args = (), device = 0, device = 1 }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this error originates in the macro `$crate::offload` which comes from the expansion of the macro `core::offload::offload` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 9 previous errors
 
diff --git a/tests/ui/offload/offload_negative_device.rs b/tests/ui/offload/offload_negative_device.rs
new file mode 100644
index 0000000000000..b47dc5f085315
--- /dev/null
+++ b/tests/ui/offload/offload_negative_device.rs
@@ -0,0 +1,12 @@
+//@ compile-flags: -Zunstable-options -Zoffload=Test -Clto=fat --emit=llvm-ir -Zdeduplicate-diagnostics=yes
+//@ no-prefer-dynamic
+//@ needs-offload
+
+#![feature(gpu_offload)]
+
+fn kernel() {}
+
+fn main() {
+    core::offload::offload! { kernel = kernel, args = (), device = -1 }
+    //~^ ERROR evaluation panicked: offload device must be non-negative; omit `device` to use the default device
+}
diff --git a/tests/ui/offload/offload_negative_device.stderr b/tests/ui/offload/offload_negative_device.stderr
new file mode 100644
index 0000000000000..4be386dd436da
--- /dev/null
+++ b/tests/ui/offload/offload_negative_device.stderr
@@ -0,0 +1,19 @@
+error[E0080]: evaluation panicked: offload device must be non-negative; omit `device` to use the default device
+  --> $DIR/offload_negative_device.rs:10:5
+   |
+LL |     core::offload::offload! { kernel = kernel, args = (), device = -1 }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::{constant#0}` failed here
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2021` which comes from the expansion of the macro `core::offload::offload` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: erroneous constant encountered
+  --> $DIR/offload_negative_device.rs:10:5
+   |
+LL |     core::offload::offload! { kernel = kernel, args = (), device = -1 }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this note originates in the macro `$crate::offload` which comes from the expansion of the macro `core::offload::offload` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.
diff --git a/tests/ui/offload/type_mismatch.rs b/tests/ui/offload/type_mismatch.rs
index 4079444a0aff1..a75f8358b7359 100644
--- a/tests/ui/offload/type_mismatch.rs
+++ b/tests/ui/offload/type_mismatch.rs
@@ -5,25 +5,32 @@
 fn main() {
     // kernel_ty is not a function item
     let not_fn = 42;
-    core::intrinsics::offload::<_, _, ()>(not_fn, [1, 1, 1], [1, 1, 1], 0, ());
+    core::intrinsics::offload::<_, _, ()>(not_fn, [1, 1, 1], [1, 1, 1], 0, -1, ());
     //~^ ERROR expected a function item for the offload kernel, found `i32`
 
     // argument count mismatch
-    core::intrinsics::offload::<_, _, ()>(kernel_1, [1, 1, 1], [1, 1, 1], 0, ());
+    core::intrinsics::offload::<_, _, ()>(kernel_1, [1, 1, 1], [1, 1, 1], 0, -1, ());
     //~^ ERROR offload kernel expects 1 arguments, but 0 arguments were provided
 
     // argument type mismatch
-    core::intrinsics::offload::<_, _, ()>(kernel_1, [1, 1, 1], [1, 1, 1], 0, (42.0f64,));
+    core::intrinsics::offload::<_, _, ()>(kernel_1, [1, 1, 1], [1, 1, 1], 0, -1, (42.0f64,));
     //~^ ERROR type mismatch in offload kernel argument 0: expected `f32`, found `f64`
 
     // return type mismatch
-    let _: f64 = core::intrinsics::offload::<_, _, f64>(kernel_0, [1, 1, 1], [1, 1, 1], 0, ());
+    let _: f64 = core::intrinsics::offload::<_, _, f64>(kernel_0, [1, 1, 1], [1, 1, 1], 0, -1, ());
     //~^ ERROR offload kernel return type mismatch: kernel returns `()`, but offload call expects `f64`
 
     // multiple argument type mismatch
-    core::intrinsics::offload::<_, _, ()>(kernel_2, [1, 1, 1], [1, 1, 1], 0, (42.0f64, 42.0f64));
-    //~^ ERROR type mismatch in offload kernel argument 0: expected `f32`, found `f64`
-    //~| ERROR type mismatch in offload kernel argument 1: expected `f32`, found `f64`
+    core::intrinsics::offload::<_, _, ()>(
+        //~^ ERROR type mismatch in offload kernel argument 0: expected `f32`, found `f64`
+        //~| ERROR type mismatch in offload kernel argument 1: expected `f32`, found `f64`
+        kernel_2,
+        [1, 1, 1],
+        [1, 1, 1],
+        0,
+        -1,
+        (42.0f64, 42.0f64),
+    );
 }
 
 fn kernel_0() {}
diff --git a/tests/ui/offload/type_mismatch.stderr b/tests/ui/offload/type_mismatch.stderr
index 8cf160ca09486..808768e7cd4f3 100644
--- a/tests/ui/offload/type_mismatch.stderr
+++ b/tests/ui/offload/type_mismatch.stderr
@@ -1,37 +1,37 @@
 error: expected a function item for the offload kernel, found `i32`
   --> $DIR/type_mismatch.rs:8:5
    |
-LL |     core::intrinsics::offload::<_, _, ()>(not_fn, [1, 1, 1], [1, 1, 1], 0, ());
+LL |     core::intrinsics::offload::<_, _, ()>(not_fn, [1, 1, 1], [1, 1, 1], 0, -1, ());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: offload kernel expects 1 arguments, but 0 arguments were provided
   --> $DIR/type_mismatch.rs:12:5
    |
-LL |     core::intrinsics::offload::<_, _, ()>(kernel_1, [1, 1, 1], [1, 1, 1], 0, ());
+LL |     core::intrinsics::offload::<_, _, ()>(kernel_1, [1, 1, 1], [1, 1, 1], 0, -1, ());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: type mismatch in offload kernel argument 0: expected `f32`, found `f64`
   --> $DIR/type_mismatch.rs:16:5
    |
-LL |     core::intrinsics::offload::<_, _, ()>(kernel_1, [1, 1, 1], [1, 1, 1], 0, (42.0f64,));
+LL |     core::intrinsics::offload::<_, _, ()>(kernel_1, [1, 1, 1], [1, 1, 1], 0, -1, (42.0f64,));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: offload kernel return type mismatch: kernel returns `()`, but offload call expects `f64`
   --> $DIR/type_mismatch.rs:20:18
    |
-LL |     let _: f64 = core::intrinsics::offload::<_, _, f64>(kernel_0, [1, 1, 1], [1, 1, 1], 0, ());
+LL |     let _: f64 = core::intrinsics::offload::<_, _, f64>(kernel_0, [1, 1, 1], [1, 1, 1], 0, -1, ());
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: type mismatch in offload kernel argument 0: expected `f32`, found `f64`
   --> $DIR/type_mismatch.rs:24:5
    |
-LL |     core::intrinsics::offload::<_, _, ()>(kernel_2, [1, 1, 1], [1, 1, 1], 0, (42.0f64, 42.0f64));
+LL |     core::intrinsics::offload::<_, _, ()>(
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: type mismatch in offload kernel argument 1: expected `f32`, found `f64`
   --> $DIR/type_mismatch.rs:24:5
    |
-LL |     core::intrinsics::offload::<_, _, ()>(kernel_2, [1, 1, 1], [1, 1, 1], 0, (42.0f64, 42.0f64));
+LL |     core::intrinsics::offload::<_, _, ()>(
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 6 previous errors
diff --git a/tests/ui/proc-macro/auxiliary/panicking-attribute.rs b/tests/ui/proc-macro/auxiliary/panicking-attribute.rs
new file mode 100644
index 0000000000000..f5544030b8ec5
--- /dev/null
+++ b/tests/ui/proc-macro/auxiliary/panicking-attribute.rs
@@ -0,0 +1,8 @@
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn tester(_: TokenStream, _: TokenStream) -> TokenStream {
+    panic!();
+}
diff --git a/tests/ui/proc-macro/panicking-inner-attribute-macro.rs b/tests/ui/proc-macro/panicking-inner-attribute-macro.rs
new file mode 100644
index 0000000000000..2fef1cb83135a
--- /dev/null
+++ b/tests/ui/proc-macro/panicking-inner-attribute-macro.rs
@@ -0,0 +1,8 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/99478>.
+
+//@ proc-macro: panicking-attribute.rs
+//@ compile-flags: --crate-type=lib
+
+#![feature(custom_inner_attributes)]
+#![panicking_attribute::tester]
+//~^ ERROR custom attribute panicked
diff --git a/tests/ui/proc-macro/panicking-inner-attribute-macro.stderr b/tests/ui/proc-macro/panicking-inner-attribute-macro.stderr
new file mode 100644
index 0000000000000..cbfb29ad1ef89
--- /dev/null
+++ b/tests/ui/proc-macro/panicking-inner-attribute-macro.stderr
@@ -0,0 +1,10 @@
+error: custom attribute panicked
+  --> $DIR/panicking-inner-attribute-macro.rs:7:1
+   |
+LL | #![panicking_attribute::tester]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: message: explicit panic
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/process/win-desktop.rs b/tests/ui/process/win-desktop.rs
new file mode 100644
index 0000000000000..f5ffed42212c7
--- /dev/null
+++ b/tests/ui/process/win-desktop.rs
@@ -0,0 +1,129 @@
+// Tests `desktop` by creating a new desktop, spawning a child process onto it
+// and checking that the child reports back the expected desktop name.
+
+//@ run-pass
+//@ only-windows
+//@ needs-subprocess
+//@ edition: 2024
+
+#![feature(windows_process_extensions_desktop)]
+
+use std::os::windows::process::CommandExt;
+use std::process::{Command, Stdio};
+use std::{env, io, process};
+
+fn main() {
+    if env::args().skip(1).any(|s| s == "--child") {
+        child();
+    } else {
+        parent();
+    }
+}
+
+fn parent() {
+    let exe = env::current_exe().unwrap();
+
+    // Create a uniquely named desktop on the current window station and keep the
+    // handle alive so the desktop is not destroyed while the child runs.
+    let desktop_name = format!("rust-test-desktop-{}", process::id());
+    let desktop_name_wide: Vec<u16> = desktop_name.encode_utf16().chain([0]).collect();
+    let hdesk = unsafe {
+        CreateDesktopW(
+            desktop_name_wide.as_ptr(),
+            core::ptr::null(),
+            core::ptr::null(),
+            0,
+            GENERIC_ALL,
+            core::ptr::null(),
+        )
+    };
+    assert!(!hdesk.is_null(), "CreateDesktopW failed: {:?}", io::Error::last_os_error());
+
+    // Spawning with `.desktop` should place the child on our new desktop.
+    let output = Command::new(&exe)
+        .arg("--child")
+        .desktop(&desktop_name)
+        .stdout(Stdio::piped())
+        .output()
+        .unwrap();
+    assert!(output.status.success(), "child failed: {:?}", output);
+    let reported = String::from_utf8(output.stdout).unwrap();
+    assert!(
+        reported.trim().eq_ignore_ascii_case(&desktop_name),
+        "child ran on unexpected desktop: expected {:?}, got {:?}",
+        desktop_name,
+        reported.trim(),
+    );
+
+    // Without `.desktop` the child inherits the parent's desktop, which is
+    // not the one we just created.
+    let output = Command::new(&exe).arg("--child").stdout(Stdio::piped()).output().unwrap();
+    assert!(output.status.success(), "child failed: {:?}", output);
+    let reported = String::from_utf8(output.stdout).unwrap();
+    assert!(
+        !reported.trim().eq_ignore_ascii_case(&desktop_name),
+        "child unexpectedly ran on the created desktop {:?} without being asked to",
+        desktop_name,
+    );
+
+    unsafe { CloseDesktop(hdesk) };
+}
+
+/// Prints the name of the desktop the current process is running on.
+fn child() {
+    let hdesk = unsafe { GetThreadDesktop(GetCurrentThreadId()) };
+    assert!(!hdesk.is_null(), "GetThreadDesktop failed: {:?}", io::Error::last_os_error());
+
+    let mut buffer = [0u16; 256];
+    let mut needed = 0u32;
+    let ret = unsafe {
+        GetUserObjectInformationW(
+            hdesk,
+            UOI_NAME,
+            buffer.as_mut_ptr().cast(),
+            size_of_val(&buffer) as u32,
+            &raw mut needed,
+        )
+    };
+    assert_ne!(ret, 0, "GetUserObjectInformationW failed: {:?}", io::Error::last_os_error());
+
+    let len = buffer.iter().position(|&c| c == 0).unwrap_or(buffer.len());
+    let name = String::from_utf16(&buffer[..len]).unwrap();
+    print!("{name}");
+}
+
+// Windows API
+mod winapi {
+    use std::ffi::c_void;
+    use std::os::windows::raw::HANDLE;
+
+    pub const GENERIC_ALL: u32 = 0x10000000;
+    pub const UOI_NAME: i32 = 2;
+
+    #[link(name = "user32")]
+    unsafe extern "system" {
+        pub fn CreateDesktopW(
+            lpszDesktop: *const u16,
+            lpszDevice: *const u16,
+            pDevmode: *const c_void,
+            dwFlags: u32,
+            dwDesiredAccess: u32,
+            lpsa: *const c_void,
+        ) -> HANDLE;
+        pub fn CloseDesktop(hDesktop: HANDLE) -> i32;
+        pub fn GetThreadDesktop(dwThreadId: u32) -> HANDLE;
+        pub fn GetUserObjectInformationW(
+            hObj: HANDLE,
+            nIndex: i32,
+            pvInfo: *mut c_void,
+            nLength: u32,
+            lpnLengthNeeded: *mut u32,
+        ) -> i32;
+    }
+
+    #[link(name = "kernel32")]
+    unsafe extern "system" {
+        pub fn GetCurrentThreadId() -> u32;
+    }
+}
+use winapi::*;
diff --git a/tests/ui/std/overflow-check-ops.rs b/tests/ui/std/overflow-check-ops.rs
new file mode 100644
index 0000000000000..458c1b121664e
--- /dev/null
+++ b/tests/ui/std/overflow-check-ops.rs
@@ -0,0 +1,45 @@
+//! Verify the behavior differences between enabling and disabling overflow checks.
+
+//@ run-pass
+//@ needs-unwind
+//@ revisions: ERROR WRAP
+//@[ERROR] compile-flags: -C overflow-checks=true
+//@[WRAP] compile-flags: -C overflow-checks=false
+
+#![feature(cfg_overflow_checks)]
+#![feature(funnel_shifts)]
+
+use std::hint::black_box as bb;
+use std::{assert_matches, fmt, panic};
+
+#[track_caller]
+fn check<T: fmt::Debug + PartialEq>(func: fn() -> T, wrapping_res: T, name: &str) {
+    let type_name = std::any::type_name::<T>();
+    let res = panic::catch_unwind(func);
+    if cfg!(overflow_checks) {
+        assert_matches!(res, Err(_), "{type_name} {name}");
+    } else {
+        assert_eq!(res.unwrap(), wrapping_res, "{type_name} {name}");
+    }
+}
+
+fn main() {
+    check(|| bb(u32::MAX) + bb(1), 0, "add");
+    check(|| bb(0u32) - bb(1), u32::MAX, "sub");
+    check(|| bb(u32::MAX) * bb(2), u32::MAX << 1, "mul");
+    check(|| bb(1u32) << bb(32), 1, "shl");
+    check(|| bb(u32::MAX) >> bb(32), u32::MAX, "shr");
+    check(|| bb(1234u32).funnel_shl(4567, bb(32)), 1234, "funnel_shl");
+    check(|| bb(1234u32).funnel_shr(4567, bb(32)), 4567, "funnel_shr");
+    check(|| bb(u32::MAX).pow(bb(2)), 1, "pow");
+    check(|| bb(u32::MAX).next_power_of_two(), 0, "next_power_of_two");
+
+    check(|| bb(i32::MAX) + bb(1), i32::MIN, "add");
+    check(|| bb(i32::MIN) - bb(1), i32::MAX, "sub");
+    check(|| bb(i32::MAX) * bb(2), i32::MAX << 1, "mul");
+    check(|| -bb(i32::MIN), i32::MIN, "neg");
+    check(|| bb(i32::MIN).abs(), i32::MIN, "abs");
+    check(|| bb(1) << bb(32), 1, "shl");
+    check(|| bb(i32::MAX) >> bb(32), i32::MAX, "shr");
+    check(|| bb(i32::MAX).pow(bb(2)), 1, "pow");
+}
diff --git a/tests/ui/suggestions/let-binding-init-expr-as-ty.rs b/tests/ui/suggestions/let-binding-init-expr-as-ty.rs
index 22240d02d7fd2..b70bf5572a57c 100644
--- a/tests/ui/suggestions/let-binding-init-expr-as-ty.rs
+++ b/tests/ui/suggestions/let-binding-init-expr-as-ty.rs
@@ -28,6 +28,17 @@ fn main() {
     //~^ ERROR return type notation is experimental
     let x: S::new(()); //~ ERROR expected type, found associated function call
 
+    // Macros — suggestion must point at user code, not the macro definition (#158492)
+    let x: vec![]; //~ ERROR expected type, found associated function call
+
+    // When the `let` is inside a macro, no suggestion should be emitted at the call site
+    macro_rules! make {
+        ($pat:pat) => {
+            let $pat: Vec::new(); //~ ERROR expected type, found associated function call
+        };
+    }
+    make!(_);
+
     // Literals
     let x: 42; //~ ERROR expected type, found `42`
     let x: ""; //~ ERROR expected type, found `""`
diff --git a/tests/ui/suggestions/let-binding-init-expr-as-ty.stderr b/tests/ui/suggestions/let-binding-init-expr-as-ty.stderr
index c096fd8c5556e..35198467409e8 100644
--- a/tests/ui/suggestions/let-binding-init-expr-as-ty.stderr
+++ b/tests/ui/suggestions/let-binding-init-expr-as-ty.stderr
@@ -1,5 +1,5 @@
 error: expected type, found `42`
-  --> $DIR/let-binding-init-expr-as-ty.rs:32:12
+  --> $DIR/let-binding-init-expr-as-ty.rs:43:12
    |
 LL |     let x: 42;
    |          - ^^ expected type
@@ -13,7 +13,7 @@ LL +     let x = 42;
    |
 
 error: expected type, found `""`
-  --> $DIR/let-binding-init-expr-as-ty.rs:33:12
+  --> $DIR/let-binding-init-expr-as-ty.rs:44:12
    |
 LL |     let x: "";
    |          - ^^ expected type
@@ -40,7 +40,7 @@ LL +     let foo = i32::from_be(num);
    |
 
 error[E0573]: cannot find type `bar` in this scope
-  --> $DIR/let-binding-init-expr-as-ty.rs:36:12
+  --> $DIR/let-binding-init-expr-as-ty.rs:47:12
    |
 LL |     let x: bar();
    |            ^^^ not found in this scope
@@ -53,7 +53,7 @@ LL +     let x = bar();
    |
 
 error[E0573]: cannot find type `bar` in this scope
-  --> $DIR/let-binding-init-expr-as-ty.rs:37:12
+  --> $DIR/let-binding-init-expr-as-ty.rs:48:12
    |
 LL |     let x: bar;
    |            ^^^ not found in this scope
@@ -61,7 +61,7 @@ LL |     let x: bar;
    = note: a function named `bar` exists in another namespace
 
 error[E0573]: cannot find type `x` in this scope
-  --> $DIR/let-binding-init-expr-as-ty.rs:40:12
+  --> $DIR/let-binding-init-expr-as-ty.rs:51:12
    |
 LL | struct K(S::new(()));
    | --------------------- similarly named struct `K` defined here
@@ -158,7 +158,30 @@ LL -     let x: S::new(());
 LL +     let x = S::new(());
    |
 
-error: aborting due to 13 previous errors
+error: expected type, found associated function call
+  --> $DIR/let-binding-init-expr-as-ty.rs:32:12
+   |
+LL |     let x: vec![];
+   |            ^^^^^^
+   |
+help: use `=` if you meant to assign
+   |
+LL -     let x: vec![];
+LL +     let x = vec![];
+   |
+
+error: expected type, found associated function call
+  --> $DIR/let-binding-init-expr-as-ty.rs:37:23
+   |
+LL |             let $pat: Vec::new();
+   |                       ^^^^^^^^^^
+...
+LL |     make!(_);
+   |     -------- in this macro invocation
+   |
+   = note: this error originates in the macro `make` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 15 previous errors
 
 Some errors have detailed explanations: E0573, E0658.
 For more information about an error, try `rustc --explain E0573`.
diff --git a/triagebot.toml b/triagebot.toml
index a842b2a07c15f..4990c72ffce6c 100644
--- a/triagebot.toml
+++ b/triagebot.toml
@@ -1581,6 +1581,7 @@ cc = ["@rust-lang/wg-const-eval"]
 [assign]
 warn_non_default_branch.enable = true
 contributing_url = "https://rustc-dev-guide.rust-lang.org/getting-started.html"
+llm_policy_url = "https://forge.rust-lang.org/policies/llm-usage.html"
 
 [[assign.warn_non_default_branch.exceptions]]
 title = "[beta"