Merge from rustc

157 files changed, 1953 insertions, 599 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
index 841cb782bc3..3e474225afd 100644
--- a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
@@ -622,8 +622,25 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
             }
         }
 
+        // NLL doesn't consider boring locals for liveness, and wouldn't encounter a
+        // `Cause::LiveVar` for such a local. Polonius can't avoid computing liveness for boring
+        // locals yet, and will encounter them when trying to explain why a borrow contains a given
+        // point.
+        //
+        // We want to focus on relevant live locals in diagnostics, so when polonius is enabled, we
+        // ensure that we don't emit live boring locals as explanations.
+        let is_local_boring = |local| {
+            if let Some(polonius_diagnostics) = self.polonius_diagnostics {
+                polonius_diagnostics.boring_nll_locals.contains(&local)
+            } else {
+                assert!(!tcx.sess.opts.unstable_opts.polonius.is_next_enabled());
+
+                // Boring locals are never the cause of a borrow explanation in NLLs.
+                false
+            }
+        };
         match find_use::find(body, regioncx, tcx, region_sub, use_location) {
-            Some(Cause::LiveVar(local, location)) => {
+            Some(Cause::LiveVar(local, location)) if !is_local_boring(local) => {
                 let span = body.source_info(location).span;
                 let spans = self
                     .move_spans(Place::from(local).as_ref(), location)
@@ -666,7 +683,9 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
                 }
             }
 
-            None => {
+            Some(Cause::LiveVar(..)) | None => {
+                // Here, under NLL: no cause was found. Under polonius: no cause was found, or a
+                // boring local was found, which we ignore like NLLs do to match its diagnostics.
                 if let Some(region) = self.to_error_region_vid(borrow_region_vid) {
                     let (category, from_closure, span, region_name, path) =
                         self.free_region_constraint_info(borrow_region_vid, region);
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 077d8f49df8..8ddc8add675 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -60,6 +60,7 @@ use crate::diagnostics::{
 use crate::path_utils::*;
 use crate::place_ext::PlaceExt;
 use crate::places_conflict::{PlaceConflictBias, places_conflict};
+use crate::polonius::PoloniusDiagnosticsContext;
 use crate::polonius::legacy::{PoloniusLocationTable, PoloniusOutput};
 use crate::prefixes::PrefixSet;
 use crate::region_infer::RegionInferenceContext;
@@ -198,7 +199,7 @@ fn do_mir_borrowck<'tcx>(
         polonius_output,
         opt_closure_req,
         nll_errors,
-        localized_outlives_constraints,
+        polonius_diagnostics,
     } = nll::compute_regions(
         &infcx,
         free_regions,
@@ -270,6 +271,7 @@ fn do_mir_borrowck<'tcx>(
             polonius_output: None,
             move_errors: Vec::new(),
             diags_buffer,
+            polonius_diagnostics: polonius_diagnostics.as_ref(),
         };
         struct MoveVisitor<'a, 'b, 'infcx, 'tcx> {
             ctxt: &'a mut MirBorrowckCtxt<'b, 'infcx, 'tcx>,
@@ -308,6 +310,7 @@ fn do_mir_borrowck<'tcx>(
         polonius_output,
         move_errors: Vec::new(),
         diags_buffer,
+        polonius_diagnostics: polonius_diagnostics.as_ref(),
     };
 
     // Compute and report region errors, if any.
@@ -329,7 +332,7 @@ fn do_mir_borrowck<'tcx>(
         body,
         &regioncx,
         &borrow_set,
-        localized_outlives_constraints,
+        polonius_diagnostics.as_ref(),
         &opt_closure_req,
     );
 
@@ -579,6 +582,9 @@ struct MirBorrowckCtxt<'a, 'infcx, 'tcx> {
 
     diags_buffer: &'a mut BorrowckDiagnosticsBuffer<'infcx, 'tcx>,
     move_errors: Vec<MoveError<'tcx>>,
+
+    /// When using `-Zpolonius=next`: the data used to compute errors and diagnostics.
+    polonius_diagnostics: Option<&'a PoloniusDiagnosticsContext>,
 }
 
 // Check that:
diff --git a/compiler/rustc_borrowck/src/nll.rs b/compiler/rustc_borrowck/src/nll.rs
index 35264bd1a70..2031579dfd5 100644
--- a/compiler/rustc_borrowck/src/nll.rs
+++ b/compiler/rustc_borrowck/src/nll.rs
@@ -27,7 +27,7 @@ use tracing::{debug, instrument};
 use crate::borrow_set::BorrowSet;
 use crate::consumers::ConsumerOptions;
 use crate::diagnostics::{BorrowckDiagnosticsBuffer, RegionErrors};
-use crate::polonius::LocalizedOutlivesConstraintSet;
+use crate::polonius::PoloniusDiagnosticsContext;
 use crate::polonius::legacy::{
     PoloniusFacts, PoloniusFactsExt, PoloniusLocationTable, PoloniusOutput,
 };
@@ -46,8 +46,9 @@ pub(crate) struct NllOutput<'tcx> {
     pub opt_closure_req: Option<ClosureRegionRequirements<'tcx>>,
     pub nll_errors: RegionErrors<'tcx>,
 
-    /// When using `-Zpolonius=next`: the localized typeck and liveness constraints.
-    pub localized_outlives_constraints: Option<LocalizedOutlivesConstraintSet>,
+    /// When using `-Zpolonius=next`: the data used to compute errors and diagnostics, e.g.
+    /// localized typeck and liveness constraints.
+    pub polonius_diagnostics: Option<PoloniusDiagnosticsContext>,
 }
 
 /// Rewrites the regions in the MIR to use NLL variables, also scraping out the set of universal
@@ -144,7 +145,7 @@ pub(crate) fn compute_regions<'a, 'tcx>(
 
     // If requested for `-Zpolonius=next`, convert NLL constraints to localized outlives constraints
     // and use them to compute loan liveness.
-    let localized_outlives_constraints = polonius_context.as_ref().map(|polonius_context| {
+    let polonius_diagnostics = polonius_context.map(|polonius_context| {
         polonius_context.compute_loan_liveness(infcx.tcx, &mut regioncx, body, borrow_set)
     });
 
@@ -188,7 +189,7 @@ pub(crate) fn compute_regions<'a, 'tcx>(
         polonius_output,
         opt_closure_req: closure_region_requirements,
         nll_errors,
-        localized_outlives_constraints,
+        polonius_diagnostics,
     }
 }
 
diff --git a/compiler/rustc_borrowck/src/polonius/dump.rs b/compiler/rustc_borrowck/src/polonius/dump.rs
index 6d32ee17f4c..5f9fa3612b8 100644
--- a/compiler/rustc_borrowck/src/polonius/dump.rs
+++ b/compiler/rustc_borrowck/src/polonius/dump.rs
@@ -12,7 +12,9 @@ use rustc_session::config::MirIncludeSpans;
 
 use crate::borrow_set::BorrowSet;
 use crate::constraints::OutlivesConstraint;
-use crate::polonius::{LocalizedOutlivesConstraint, LocalizedOutlivesConstraintSet};
+use crate::polonius::{
+    LocalizedOutlivesConstraint, LocalizedOutlivesConstraintSet, PoloniusDiagnosticsContext,
+};
 use crate::region_infer::values::LivenessValues;
 use crate::type_check::Locations;
 use crate::{BorrowckInferCtxt, RegionInferenceContext};
@@ -23,7 +25,7 @@ pub(crate) fn dump_polonius_mir<'tcx>(
     body: &Body<'tcx>,
     regioncx: &RegionInferenceContext<'tcx>,
     borrow_set: &BorrowSet<'tcx>,
-    localized_outlives_constraints: Option<LocalizedOutlivesConstraintSet>,
+    polonius_diagnostics: Option<&PoloniusDiagnosticsContext>,
     closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
 ) {
     let tcx = infcx.tcx;
@@ -35,8 +37,8 @@ pub(crate) fn dump_polonius_mir<'tcx>(
         return;
     }
 
-    let localized_outlives_constraints = localized_outlives_constraints
-        .expect("missing localized constraints with `-Zpolonius=next`");
+    let polonius_diagnostics =
+        polonius_diagnostics.expect("missing diagnostics context with `-Zpolonius=next`");
 
     let _: io::Result<()> = try {
         let mut file = create_dump_file(tcx, "html", false, "polonius", &0, body)?;
@@ -45,7 +47,7 @@ pub(crate) fn dump_polonius_mir<'tcx>(
             body,
             regioncx,
             borrow_set,
-            localized_outlives_constraints,
+            &polonius_diagnostics.localized_outlives_constraints,
             closure_region_requirements,
             &mut file,
         )?;
@@ -63,7 +65,7 @@ fn emit_polonius_dump<'tcx>(
     body: &Body<'tcx>,
     regioncx: &RegionInferenceContext<'tcx>,
     borrow_set: &BorrowSet<'tcx>,
-    localized_outlives_constraints: LocalizedOutlivesConstraintSet,
+    localized_outlives_constraints: &LocalizedOutlivesConstraintSet,
     closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
     out: &mut dyn io::Write,
 ) -> io::Result<()> {
diff --git a/compiler/rustc_borrowck/src/polonius/liveness_constraints.rs b/compiler/rustc_borrowck/src/polonius/liveness_constraints.rs
index 75ee29c9d0d..6ab09f731c0 100644
--- a/compiler/rustc_borrowck/src/polonius/liveness_constraints.rs
+++ b/compiler/rustc_borrowck/src/polonius/liveness_constraints.rs
@@ -1,7 +1,6 @@
 use std::collections::BTreeMap;
 
 use rustc_index::bit_set::SparseBitMatrix;
-use rustc_index::interval::SparseIntervalMatrix;
 use rustc_middle::mir::{Body, Location};
 use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
 use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt, TypeVisitable};
@@ -9,12 +8,12 @@ use rustc_mir_dataflow::points::PointIndex;
 
 use super::{
     ConstraintDirection, LocalizedOutlivesConstraint, LocalizedOutlivesConstraintSet,
-    PoloniusContext,
+    PoloniusLivenessContext,
 };
 use crate::region_infer::values::LivenessValues;
 use crate::universal_regions::UniversalRegions;
 
-impl PoloniusContext {
+impl PoloniusLivenessContext {
     /// Record the variance of each region contained within the given value.
     pub(crate) fn record_live_region_variance<'tcx>(
         &mut self,
@@ -30,25 +29,6 @@ impl PoloniusContext {
         };
         extractor.relate(value, value).expect("Can't have a type error relating to itself");
     }
-
-    /// Unlike NLLs, in polonius we traverse the cfg to look for regions live across an edge, so we
-    /// need to transpose the "points where each region is live" matrix to a "live regions per point"
-    /// matrix.
-    // FIXME: avoid this conversion by always storing liveness data in this shape in the rest of
-    // borrowck.
-    pub(crate) fn record_live_regions_per_point(
-        &mut self,
-        num_regions: usize,
-        points_per_live_region: &SparseIntervalMatrix<RegionVid, PointIndex>,
-    ) {
-        let mut live_regions_per_point = SparseBitMatrix::new(num_regions);
-        for region in points_per_live_region.rows() {
-            for point in points_per_live_region.row(region).unwrap().iter() {
-                live_regions_per_point.insert(point, region);
-            }
-        }
-        self.live_regions = Some(live_regions_per_point);
-    }
 }
 
 /// Propagate loans throughout the CFG: for each statement in the MIR, create localized outlives
diff --git a/compiler/rustc_borrowck/src/polonius/mod.rs b/compiler/rustc_borrowck/src/polonius/mod.rs
index 502c868194a..142ef8ba28e 100644
--- a/compiler/rustc_borrowck/src/polonius/mod.rs
+++ b/compiler/rustc_borrowck/src/polonius/mod.rs
@@ -32,6 +32,16 @@
 //! - <https://smallcultfollowing.com/babysteps/blog/2023/09/22/polonius-part-1/>
 //! - <https://smallcultfollowing.com/babysteps/blog/2023/09/29/polonius-part-2/>
 //!
+//!
+//! Data flows like this:
+//! 1) during MIR typeck, record liveness data needed later: live region variances, as well as the
+//!    usual NLL liveness data (just computed on more locals). That's the [PoloniusLivenessContext].
+//! 2) once that is done, variance data is transferred, and the NLL region liveness is converted to
+//!    the polonius shape. That's the main [PoloniusContext].
+//! 3) during region inference, that data and the NLL outlives constraints are used to create the
+//!    localized outlives constraints, as described above. That's the [PoloniusDiagnosticsContext].
+//! 4) transfer this back to the main borrowck procedure: it handles computing errors and
+//!    diagnostics, debugging and MIR dumping concerns.
 
 mod constraints;
 mod dump;
@@ -42,8 +52,10 @@ mod typeck_constraints;
 
 use std::collections::BTreeMap;
 
+use rustc_data_structures::fx::FxHashSet;
 use rustc_index::bit_set::SparseBitMatrix;
-use rustc_middle::mir::Body;
+use rustc_index::interval::SparseIntervalMatrix;
+use rustc_middle::mir::{Body, Local};
 use rustc_middle::ty::{RegionVid, TyCtxt};
 use rustc_mir_dataflow::points::PointIndex;
 
@@ -57,15 +69,40 @@ use crate::{BorrowSet, RegionInferenceContext};
 
 pub(crate) type LiveLoans = SparseBitMatrix<PointIndex, BorrowIndex>;
 
-/// This struct holds the data needed to create the Polonius localized constraints.
+/// This struct holds the liveness data created during MIR typeck, and which will be used later in
+/// the process, to compute the polonius localized constraints.
+#[derive(Default)]
+pub(crate) struct PoloniusLivenessContext {
+    /// The expected edge direction per live region: the kind of directed edge we'll create as
+    /// liveness constraints depends on the variance of types with respect to each contained region.
+    live_region_variances: BTreeMap<RegionVid, ConstraintDirection>,
+
+    /// The regions that outlive free regions are used to distinguish relevant live locals from
+    /// boring locals. A boring local is one whose type contains only such regions. Polonius
+    /// currently has more boring locals than NLLs so we record the latter to use in errors and
+    /// diagnostics, to focus on the locals we consider relevant and match NLL diagnostics.
+    pub(crate) boring_nll_locals: FxHashSet<Local>,
+}
+
+/// This struct holds the data needed to create the Polonius localized constraints. Its data is
+/// transferred and converted from the [PoloniusLivenessContext] at the end of MIR typeck.
 pub(crate) struct PoloniusContext {
+    /// The liveness data we recorded during MIR typeck.
+    liveness_context: PoloniusLivenessContext,
+
     /// The set of regions that are live at a given point in the CFG, used to create localized
     /// outlives constraints between regions that are live at connected points in the CFG.
-    live_regions: Option<SparseBitMatrix<PointIndex, RegionVid>>,
+    live_regions: SparseBitMatrix<PointIndex, RegionVid>,
+}
 
-    /// The expected edge direction per live region: the kind of directed edge we'll create as
-    /// liveness constraints depends on the variance of types with respect to each contained region.
-    live_region_variances: BTreeMap<RegionVid, ConstraintDirection>,
+/// This struct holds the data needed by the borrowck error computation and diagnostics. Its data is
+/// computed from the [PoloniusContext] when computing NLL regions.
+pub(crate) struct PoloniusDiagnosticsContext {
+    /// The localized outlives constraints that were computed in the main analysis.
+    localized_outlives_constraints: LocalizedOutlivesConstraintSet,
+
+    /// The liveness data computed during MIR typeck: [PoloniusLivenessContext::boring_nll_locals].
+    pub(crate) boring_nll_locals: FxHashSet<Local>,
 }
 
 /// The direction a constraint can flow into. Used to create liveness constraints according to
@@ -83,8 +120,24 @@ enum ConstraintDirection {
 }
 
 impl PoloniusContext {
-    pub(crate) fn new() -> PoloniusContext {
-        Self { live_region_variances: BTreeMap::new(), live_regions: None }
+    /// Unlike NLLs, in polonius we traverse the cfg to look for regions live across an edge, so we
+    /// need to transpose the "points where each region is live" matrix to a "live regions per point"
+    /// matrix.
+    // FIXME: avoid this conversion by always storing liveness data in this shape in the rest of
+    // borrowck.
+    pub(crate) fn create_from_liveness(
+        liveness_context: PoloniusLivenessContext,
+        num_regions: usize,
+        points_per_live_region: &SparseIntervalMatrix<RegionVid, PointIndex>,
+    ) -> PoloniusContext {
+        let mut live_regions_per_point = SparseBitMatrix::new(num_regions);
+        for region in points_per_live_region.rows() {
+            for point in points_per_live_region.row(region).unwrap().iter() {
+                live_regions_per_point.insert(point, region);
+            }
+        }
+
+        PoloniusContext { live_regions: live_regions_per_point, liveness_context }
     }
 
     /// Computes live loans using the set of loans model for `-Zpolonius=next`.
@@ -95,13 +148,18 @@ impl PoloniusContext {
     ///
     /// Then, this graph is traversed, and combined with kills, reachability is recorded as loan
     /// liveness, to be used by the loan scope and active loans computations.
+    ///
+    /// The constraint data will be used to compute errors and diagnostics.
     pub(crate) fn compute_loan_liveness<'tcx>(
-        &self,
+        self,
         tcx: TyCtxt<'tcx>,
         regioncx: &mut RegionInferenceContext<'tcx>,
         body: &Body<'tcx>,
         borrow_set: &BorrowSet<'tcx>,
-    ) -> LocalizedOutlivesConstraintSet {
+    ) -> PoloniusDiagnosticsContext {
+        let PoloniusLivenessContext { live_region_variances, boring_nll_locals } =
+            self.liveness_context;
+
         let mut localized_outlives_constraints = LocalizedOutlivesConstraintSet::default();
         convert_typeck_constraints(
             tcx,
@@ -112,14 +170,11 @@ impl PoloniusContext {
             &mut localized_outlives_constraints,
         );
 
-        let live_regions = self.live_regions.as_ref().expect(
-            "live regions per-point data should have been created at the end of MIR typeck",
-        );
         create_liveness_constraints(
             body,
             regioncx.liveness_constraints(),
-            live_regions,
-            &self.live_region_variances,
+            &self.live_regions,
+            &live_region_variances,
             regioncx.universal_regions(),
             &mut localized_outlives_constraints,
         );
@@ -136,6 +191,6 @@ impl PoloniusContext {
         );
         regioncx.record_live_loans(live_loans);
 
-        localized_outlives_constraints
+        PoloniusDiagnosticsContext { localized_outlives_constraints, boring_nll_locals }
     }
 }
diff --git a/compiler/rustc_borrowck/src/type_check/liveness/mod.rs b/compiler/rustc_borrowck/src/type_check/liveness/mod.rs
index 4e0b2a4e296..dcc17903002 100644
--- a/compiler/rustc_borrowck/src/type_check/liveness/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/liveness/mod.rs
@@ -14,7 +14,7 @@ use tracing::debug;
 
 use super::TypeChecker;
 use crate::constraints::OutlivesConstraintSet;
-use crate::polonius::PoloniusContext;
+use crate::polonius::PoloniusLivenessContext;
 use crate::region_infer::values::LivenessValues;
 use crate::universal_regions::UniversalRegions;
 
@@ -38,19 +38,24 @@ pub(super) fn generate<'a, 'tcx>(
 ) {
     debug!("liveness::generate");
 
+    let mut free_regions = regions_that_outlive_free_regions(
+        typeck.infcx.num_region_vars(),
+        &typeck.universal_regions,
+        &typeck.constraints.outlives_constraints,
+    );
+
     // NLLs can avoid computing some liveness data here because its constraints are
     // location-insensitive, but that doesn't work in polonius: locals whose type contains a region
     // that outlives a free region are not necessarily live everywhere in a flow-sensitive setting,
     // unlike NLLs.
-    let free_regions = if !typeck.tcx().sess.opts.unstable_opts.polonius.is_next_enabled() {
-        regions_that_outlive_free_regions(
-            typeck.infcx.num_region_vars(),
-            &typeck.universal_regions,
-            &typeck.constraints.outlives_constraints,
-        )
-    } else {
-        typeck.universal_regions.universal_regions_iter().collect()
-    };
+    // We do record these regions in the polonius context, since they're used to differentiate
+    // relevant and boring locals, which is a key distinction used later in diagnostics.
+    if typeck.tcx().sess.opts.unstable_opts.polonius.is_next_enabled() {
+        let (_, boring_locals) = compute_relevant_live_locals(typeck.tcx(), &free_regions, body);
+        typeck.polonius_liveness.as_mut().unwrap().boring_nll_locals =
+            boring_locals.into_iter().collect();
+        free_regions = typeck.universal_regions.universal_regions_iter().collect();
+    }
     let (relevant_live_locals, boring_locals) =
         compute_relevant_live_locals(typeck.tcx(), &free_regions, body);
 
@@ -70,7 +75,7 @@ pub(super) fn generate<'a, 'tcx>(
         typeck.tcx(),
         &mut typeck.constraints.liveness_constraints,
         &typeck.universal_regions,
-        &mut typeck.polonius_context,
+        &mut typeck.polonius_liveness,
         body,
     );
 }
@@ -147,11 +152,11 @@ fn record_regular_live_regions<'tcx>(
     tcx: TyCtxt<'tcx>,
     liveness_constraints: &mut LivenessValues,
     universal_regions: &UniversalRegions<'tcx>,
-    polonius_context: &mut Option<PoloniusContext>,
+    polonius_liveness: &mut Option<PoloniusLivenessContext>,
     body: &Body<'tcx>,
 ) {
     let mut visitor =
-        LiveVariablesVisitor { tcx, liveness_constraints, universal_regions, polonius_context };
+        LiveVariablesVisitor { tcx, liveness_constraints, universal_regions, polonius_liveness };
     for (bb, data) in body.basic_blocks.iter_enumerated() {
         visitor.visit_basic_block_data(bb, data);
     }
@@ -162,7 +167,7 @@ struct LiveVariablesVisitor<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     liveness_constraints: &'a mut LivenessValues,
     universal_regions: &'a UniversalRegions<'tcx>,
-    polonius_context: &'a mut Option<PoloniusContext>,
+    polonius_liveness: &'a mut Option<PoloniusLivenessContext>,
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for LiveVariablesVisitor<'a, 'tcx> {
@@ -214,8 +219,8 @@ impl<'a, 'tcx> LiveVariablesVisitor<'a, 'tcx> {
         });
 
         // When using `-Zpolonius=next`, we record the variance of each live region.
-        if let Some(polonius_context) = self.polonius_context {
-            polonius_context.record_live_region_variance(self.tcx, self.universal_regions, value);
+        if let Some(polonius_liveness) = self.polonius_liveness {
+            polonius_liveness.record_live_region_variance(self.tcx, self.universal_regions, value);
         }
     }
 }
diff --git a/compiler/rustc_borrowck/src/type_check/liveness/trace.rs b/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
index c564d85616e..62d49a62744 100644
--- a/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
+++ b/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
@@ -580,8 +580,8 @@ impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
         });
 
         // When using `-Zpolonius=next`, we record the variance of each live region.
-        if let Some(polonius_context) = typeck.polonius_context {
-            polonius_context.record_live_region_variance(
+        if let Some(polonius_liveness) = typeck.polonius_liveness.as_mut() {
+            polonius_liveness.record_live_region_variance(
                 typeck.infcx.tcx,
                 typeck.universal_regions,
                 value,
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 92492bfdb8d..78aa38e9e48 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -48,8 +48,8 @@ use crate::borrow_set::BorrowSet;
 use crate::constraints::{OutlivesConstraint, OutlivesConstraintSet};
 use crate::diagnostics::UniverseInfo;
 use crate::member_constraints::MemberConstraintSet;
-use crate::polonius::PoloniusContext;
 use crate::polonius::legacy::{PoloniusFacts, PoloniusLocationTable};
+use crate::polonius::{PoloniusContext, PoloniusLivenessContext};
 use crate::region_infer::TypeTest;
 use crate::region_infer::values::{LivenessValues, PlaceholderIndex, PlaceholderIndices};
 use crate::renumber::RegionCtxt;
@@ -148,8 +148,8 @@ pub(crate) fn type_check<'a, 'tcx>(
 
     debug!(?normalized_inputs_and_output);
 
-    let mut polonius_context = if infcx.tcx.sess.opts.unstable_opts.polonius.is_next_enabled() {
-        Some(PoloniusContext::new())
+    let polonius_liveness = if infcx.tcx.sess.opts.unstable_opts.polonius.is_next_enabled() {
+        Some(PoloniusLivenessContext::default())
     } else {
         None
     };
@@ -168,7 +168,7 @@ pub(crate) fn type_check<'a, 'tcx>(
         polonius_facts,
         borrow_set,
         constraints: &mut constraints,
-        polonius_context: &mut polonius_context,
+        polonius_liveness,
     };
 
     typeck.check_user_type_annotations();
@@ -185,11 +185,14 @@ pub(crate) fn type_check<'a, 'tcx>(
     let opaque_type_values =
         opaque_types::take_opaques_and_register_member_constraints(&mut typeck);
 
-    if let Some(polonius_context) = typeck.polonius_context.as_mut() {
-        let num_regions = infcx.num_region_vars();
-        let points_per_live_region = typeck.constraints.liveness_constraints.points();
-        polonius_context.record_live_regions_per_point(num_regions, points_per_live_region);
-    }
+    // We're done with typeck, we can finalize the polonius liveness context for region inference.
+    let polonius_context = typeck.polonius_liveness.take().map(|liveness_context| {
+        PoloniusContext::create_from_liveness(
+            liveness_context,
+            infcx.num_region_vars(),
+            typeck.constraints.liveness_constraints.points(),
+        )
+    });
 
     MirTypeckResults {
         constraints,
@@ -583,8 +586,8 @@ struct TypeChecker<'a, 'tcx> {
     polonius_facts: &'a mut Option<PoloniusFacts>,
     borrow_set: &'a BorrowSet<'tcx>,
     constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
-    /// When using `-Zpolonius=next`, the helper data used to create polonius constraints.
-    polonius_context: &'a mut Option<PoloniusContext>,
+    /// When using `-Zpolonius=next`, the liveness helper data used to create polonius constraints.
+    polonius_liveness: Option<PoloniusLivenessContext>,
 }
 
 /// Holder struct for passing results from MIR typeck to the rest of the non-lexical regions
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 2d007416263..b63c8f8caef 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -4,7 +4,7 @@ use std::{iter, ptr};
 
 pub(crate) mod autodiff;
 
-use libc::{c_char, c_uint};
+use libc::{c_char, c_uint, size_t};
 use rustc_abi as abi;
 use rustc_abi::{Align, Size, WrappingRange};
 use rustc_codegen_ssa::MemFlags;
@@ -32,7 +32,7 @@ use crate::abi::FnAbiLlvmExt;
 use crate::attributes;
 use crate::common::Funclet;
 use crate::context::{CodegenCx, SimpleCx};
-use crate::llvm::{self, AtomicOrdering, AtomicRmwBinOp, BasicBlock, False, True};
+use crate::llvm::{self, AtomicOrdering, AtomicRmwBinOp, BasicBlock, False, Metadata, True};
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
@@ -333,6 +333,50 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         }
     }
 
+    fn switch_with_weights(
+        &mut self,
+        v: Self::Value,
+        else_llbb: Self::BasicBlock,
+        else_is_cold: bool,
+        cases: impl ExactSizeIterator<Item = (u128, Self::BasicBlock, bool)>,
+    ) {
+        if self.cx.sess().opts.optimize == rustc_session::config::OptLevel::No {
+            self.switch(v, else_llbb, cases.map(|(val, dest, _)| (val, dest)));
+            return;
+        }
+
+        let id_str = "branch_weights";
+        let id = unsafe {
+            llvm::LLVMMDStringInContext2(self.cx.llcx, id_str.as_ptr().cast(), id_str.len())
+        };
+
+        // For switch instructions with 2 targets, the `llvm.expect` intrinsic is used.
+        // This function handles switch instructions with more than 2 targets and it needs to
+        // emit branch weights metadata instead of using the intrinsic.
+        // The values 1 and 2000 are the same as the values used by the `llvm.expect` intrinsic.
+        let cold_weight = unsafe { llvm::LLVMValueAsMetadata(self.cx.const_u32(1)) };
+        let hot_weight = unsafe { llvm::LLVMValueAsMetadata(self.cx.const_u32(2000)) };
+        let weight =
+            |is_cold: bool| -> &Metadata { if is_cold { cold_weight } else { hot_weight } };
+
+        let mut md: SmallVec<[&Metadata; 16]> = SmallVec::with_capacity(cases.len() + 2);
+        md.push(id);
+        md.push(weight(else_is_cold));
+
+        let switch =
+            unsafe { llvm::LLVMBuildSwitch(self.llbuilder, v, else_llbb, cases.len() as c_uint) };
+        for (on_val, dest, is_cold) in cases {
+            let on_val = self.const_uint_big(self.val_ty(v), on_val);
+            unsafe { llvm::LLVMAddCase(switch, on_val, dest) }
+            md.push(weight(is_cold));
+        }
+
+        unsafe {
+            let md_node = llvm::LLVMMDNodeInContext2(self.cx.llcx, md.as_ptr(), md.len() as size_t);
+            self.cx.set_metadata(switch, llvm::MD_prof, md_node);
+        }
+    }
+
     fn invoke(
         &mut self,
         llty: &'ll Type,
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index 914f2c21fa7..ce2161a07eb 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -403,7 +403,7 @@ fn generate_lto_work<B: ExtraBackendMethods>(
         assert!(needs_thin_lto.is_empty());
         let mut module =
             B::run_fat_lto(cgcx, needs_fat_lto, import_only_modules).unwrap_or_else(|e| e.raise());
-        if cgcx.lto == Lto::Fat {
+        if cgcx.lto == Lto::Fat && !autodiff.is_empty() {
             let config = cgcx.config(ModuleKind::Regular);
             module = unsafe { module.autodiff(cgcx, autodiff, config).unwrap() };
         }
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 4be363ca9a2..66008a47650 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -429,11 +429,34 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             let cmp = bx.icmp(IntPredicate::IntEQ, discr_value, llval);
             bx.cond_br(cmp, ll1, ll2);
         } else {
-            bx.switch(
-                discr_value,
-                helper.llbb_with_cleanup(self, targets.otherwise()),
-                target_iter.map(|(value, target)| (value, helper.llbb_with_cleanup(self, target))),
-            );
+            let otherwise = targets.otherwise();
+            let otherwise_cold = self.cold_blocks[otherwise];
+            let otherwise_unreachable = self.mir[otherwise].is_empty_unreachable();
+            let cold_count = targets.iter().filter(|(_, target)| self.cold_blocks[*target]).count();
+            let none_cold = cold_count == 0;
+            let all_cold = cold_count == targets.iter().len();
+            if (none_cold && (!otherwise_cold || otherwise_unreachable))
+                || (all_cold && (otherwise_cold || otherwise_unreachable))
+            {
+                // All targets have the same weight,
+                // or `otherwise` is unreachable and it's the only target with a different weight.
+                bx.switch(
+                    discr_value,
+                    helper.llbb_with_cleanup(self, targets.otherwise()),
+                    target_iter
+                        .map(|(value, target)| (value, helper.llbb_with_cleanup(self, target))),
+                );
+            } else {
+                // Targets have different weights
+                bx.switch_with_weights(
+                    discr_value,
+                    helper.llbb_with_cleanup(self, targets.otherwise()),
+                    otherwise_cold,
+                    target_iter.map(|(value, target)| {
+                        (value, helper.llbb_with_cleanup(self, target), self.cold_blocks[target])
+                    }),
+                );
+            }
         }
     }
 
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index 3a896071bc6..ba28720afec 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -502,14 +502,25 @@ fn find_cold_blocks<'tcx>(
     for (bb, bb_data) in traversal::postorder(mir) {
         let terminator = bb_data.terminator();
 
-        // If a BB ends with a call to a cold function, mark it as cold.
-        if let mir::TerminatorKind::Call { ref func, .. } = terminator.kind
-            && let ty::FnDef(def_id, ..) = *func.ty(local_decls, tcx).kind()
-            && let attrs = tcx.codegen_fn_attrs(def_id)
-            && attrs.flags.contains(CodegenFnAttrFlags::COLD)
-        {
-            cold_blocks[bb] = true;
-            continue;
+        match terminator.kind {
+            // If a BB ends with a call to a cold function, mark it as cold.
+            mir::TerminatorKind::Call { ref func, .. }
+            | mir::TerminatorKind::TailCall { ref func, .. }
+                if let ty::FnDef(def_id, ..) = *func.ty(local_decls, tcx).kind()
+                    && let attrs = tcx.codegen_fn_attrs(def_id)
+                    && attrs.flags.contains(CodegenFnAttrFlags::COLD) =>
+            {
+                cold_blocks[bb] = true;
+                continue;
+            }
+
+            // If a BB ends with an `unreachable`, also mark it as cold.
+            mir::TerminatorKind::Unreachable => {
+                cold_blocks[bb] = true;
+                continue;
+            }
+
+            _ => {}
         }
 
         // If all successors of a BB are cold and there's at least one of them, mark this BB as cold
diff --git a/compiler/rustc_codegen_ssa/src/traits/builder.rs b/compiler/rustc_codegen_ssa/src/traits/builder.rs
index bbf87a59942..cbe0f2e8059 100644
--- a/compiler/rustc_codegen_ssa/src/traits/builder.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/builder.rs
@@ -110,6 +110,20 @@ pub trait BuilderMethods<'a, 'tcx>:
         else_llbb: Self::BasicBlock,
         cases: impl ExactSizeIterator<Item = (u128, Self::BasicBlock)>,
     );
+
+    // This is like `switch()`, but every case has a bool flag indicating whether it's cold.
+    //
+    // Default implementation throws away the cold flags and calls `switch()`.
+    fn switch_with_weights(
+        &mut self,
+        v: Self::Value,
+        else_llbb: Self::BasicBlock,
+        _else_is_cold: bool,
+        cases: impl ExactSizeIterator<Item = (u128, Self::BasicBlock, bool)>,
+    ) {
+        self.switch(v, else_llbb, cases.map(|(val, bb, _)| (val, bb)))
+    }
+
     fn invoke(
         &mut self,
         llty: Self::Type,
diff --git a/compiler/rustc_const_eval/messages.ftl b/compiler/rustc_const_eval/messages.ftl
index d600d223bff..eecc6690f51 100644
--- a/compiler/rustc_const_eval/messages.ftl
+++ b/compiler/rustc_const_eval/messages.ftl
@@ -280,7 +280,9 @@ const_eval_nullary_intrinsic_fail =
     could not evaluate nullary intrinsic
 
 const_eval_offset_from_different_allocations =
-    `{$name}` called on pointers into different allocations
+    `{$name}` called on two different pointers that are not both derived from the same allocation
+const_eval_offset_from_out_of_bounds =
+    `{$name}` called on two different pointers where the memory range between them is not in-bounds of an allocation
 const_eval_offset_from_overflow =
     `{$name}` called when first pointer is too far ahead of second
 const_eval_offset_from_test =
diff --git a/compiler/rustc_const_eval/src/const_eval/mod.rs b/compiler/rustc_const_eval/src/const_eval/mod.rs
index 34f795bda75..c0438fb3ff8 100644
--- a/compiler/rustc_const_eval/src/const_eval/mod.rs
+++ b/compiler/rustc_const_eval/src/const_eval/mod.rs
@@ -1,7 +1,7 @@
 // Not in interpret to make sure we do not use private implementation details
 
 use rustc_abi::VariantIdx;
-use rustc_middle::query::{Key, TyCtxtAt};
+use rustc_middle::query::Key;
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::{bug, mir};
@@ -35,16 +35,17 @@ pub(crate) type ValTreeCreationResult<'tcx> = Result<ty::ValTree<'tcx>, ValTreeC
 
 #[instrument(skip(tcx), level = "debug")]
 pub(crate) fn try_destructure_mir_constant_for_user_output<'tcx>(
-    tcx: TyCtxtAt<'tcx>,
+    tcx: TyCtxt<'tcx>,
     val: mir::ConstValue<'tcx>,
     ty: Ty<'tcx>,
 ) -> Option<mir::DestructuredConstant<'tcx>> {
     let typing_env = ty::TypingEnv::fully_monomorphized();
-    let (ecx, op) = mk_eval_cx_for_const_val(tcx, typing_env, val, ty)?;
+    // FIXME: use a proper span here?
+    let (ecx, op) = mk_eval_cx_for_const_val(tcx.at(rustc_span::DUMMY_SP), typing_env, val, ty)?;
 
     // We go to `usize` as we cannot allocate anything bigger anyway.
     let (field_count, variant, down) = match ty.kind() {
-        ty::Array(_, len) => (len.try_to_target_usize(tcx.tcx)? as usize, None, op),
+        ty::Array(_, len) => (len.try_to_target_usize(tcx)? as usize, None, op),
         ty::Adt(def, _) if def.variants().is_empty() => {
             return None;
         }
diff --git a/compiler/rustc_const_eval/src/const_eval/valtrees.rs b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
index 4d625f76aba..c35910a706b 100644
--- a/compiler/rustc_const_eval/src/const_eval/valtrees.rs
+++ b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
@@ -273,59 +273,63 @@ pub(crate) fn eval_to_valtree<'tcx>(
 /// Converts a `ValTree` to a `ConstValue`, which is needed after mir
 /// construction has finished.
 // FIXME(valtrees): Merge `valtree_to_const_value` and `valtree_into_mplace` into one function
-// FIXME(valtrees): Accept `ty::Value` instead of `Ty` and `ty::ValTree` separately.
 #[instrument(skip(tcx), level = "debug", ret)]
 pub fn valtree_to_const_value<'tcx>(
     tcx: TyCtxt<'tcx>,
     typing_env: ty::TypingEnv<'tcx>,
-    ty: Ty<'tcx>,
-    valtree: ty::ValTree<'tcx>,
+    cv: ty::Value<'tcx>,
 ) -> mir::ConstValue<'tcx> {
     // Basic idea: We directly construct `Scalar` values from trivial `ValTree`s
     // (those for constants with type bool, int, uint, float or char).
     // For all other types we create an `MPlace` and fill that by walking
     // the `ValTree` and using `place_projection` and `place_field` to
     // create inner `MPlace`s which are filled recursively.
-    // FIXME Does this need an example?
-    match *ty.kind() {
+    // FIXME: Does this need an example?
+    match *cv.ty.kind() {
         ty::FnDef(..) => {
-            assert!(valtree.unwrap_branch().is_empty());
+            assert!(cv.valtree.unwrap_branch().is_empty());
             mir::ConstValue::ZeroSized
         }
         ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char | ty::RawPtr(_, _) => {
-            match valtree {
+            match cv.valtree {
                 ty::ValTree::Leaf(scalar_int) => mir::ConstValue::Scalar(Scalar::Int(scalar_int)),
                 ty::ValTree::Branch(_) => bug!(
                     "ValTrees for Bool, Int, Uint, Float, Char or RawPtr should have the form ValTree::Leaf"
                 ),
             }
         }
-        ty::Pat(ty, _) => valtree_to_const_value(tcx, typing_env, ty, valtree),
+        ty::Pat(ty, _) => {
+            let cv = ty::Value { valtree: cv.valtree, ty };
+            valtree_to_const_value(tcx, typing_env, cv)
+        }
         ty::Ref(_, inner_ty, _) => {
             let mut ecx =
                 mk_eval_cx_to_read_const_val(tcx, DUMMY_SP, typing_env, CanAccessMutGlobal::No);
-            let imm = valtree_to_ref(&mut ecx, valtree, inner_ty);
-            let imm =
-                ImmTy::from_immediate(imm, tcx.layout_of(typing_env.as_query_input(ty)).unwrap());
+            let imm = valtree_to_ref(&mut ecx, cv.valtree, inner_ty);
+            let imm = ImmTy::from_immediate(
+                imm,
+                tcx.layout_of(typing_env.as_query_input(cv.ty)).unwrap(),
+            );
             op_to_const(&ecx, &imm.into(), /* for diagnostics */ false)
         }
         ty::Tuple(_) | ty::Array(_, _) | ty::Adt(..) => {
-            let layout = tcx.layout_of(typing_env.as_query_input(ty)).unwrap();
+            let layout = tcx.layout_of(typing_env.as_query_input(cv.ty)).unwrap();
             if layout.is_zst() {
                 // Fast path to avoid some allocations.
                 return mir::ConstValue::ZeroSized;
             }
             if layout.backend_repr.is_scalar()
-                && (matches!(ty.kind(), ty::Tuple(_))
-                    || matches!(ty.kind(), ty::Adt(def, _) if def.is_struct()))
+                && (matches!(cv.ty.kind(), ty::Tuple(_))
+                    || matches!(cv.ty.kind(), ty::Adt(def, _) if def.is_struct()))
             {
                 // A Scalar tuple/struct; we can avoid creating an allocation.
-                let branches = valtree.unwrap_branch();
+                let branches = cv.valtree.unwrap_branch();
                 // Find the non-ZST field. (There can be aligned ZST!)
                 for (i, &inner_valtree) in branches.iter().enumerate() {
                     let field = layout.field(&LayoutCx::new(tcx, typing_env), i);
                     if !field.is_zst() {
-                        return valtree_to_const_value(tcx, typing_env, field.ty, inner_valtree);
+                        let cv = ty::Value { valtree: inner_valtree, ty: field.ty };
+                        return valtree_to_const_value(tcx, typing_env, cv);
                     }
                 }
                 bug!("could not find non-ZST field during in {layout:#?}");
@@ -335,9 +339,9 @@ pub fn valtree_to_const_value<'tcx>(
                 mk_eval_cx_to_read_const_val(tcx, DUMMY_SP, typing_env, CanAccessMutGlobal::No);
 
             // Need to create a place for this valtree.
-            let place = create_valtree_place(&mut ecx, layout, valtree);
+            let place = create_valtree_place(&mut ecx, layout, cv.valtree);
 
-            valtree_into_mplace(&mut ecx, &place, valtree);
+            valtree_into_mplace(&mut ecx, &place, cv.valtree);
             dump_place(&ecx, &place);
             intern_const_alloc_recursive(&mut ecx, InternKind::Constant, &place).unwrap();
 
@@ -362,7 +366,7 @@ pub fn valtree_to_const_value<'tcx>(
         | ty::Slice(_)
         | ty::Dynamic(..)
         | ty::UnsafeBinder(_) => {
-            bug!("no ValTree should have been created for type {:?}", ty.kind())
+            bug!("no ValTree should have been created for type {:?}", cv.ty.kind())
         }
     }
 }
diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
index 9f5f2533e08..4ca317e3a1e 100644
--- a/compiler/rustc_const_eval/src/interpret/intrinsics.rs
+++ b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
@@ -319,7 +319,25 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
                 // Check that the memory between them is dereferenceable at all, starting from the
                 // origin pointer: `dist` is `a - b`, so it is based on `b`.
-                self.check_ptr_access_signed(b, dist, CheckInAllocMsg::OffsetFromTest)?;
+                self.check_ptr_access_signed(b, dist, CheckInAllocMsg::OffsetFromTest)
+                    .map_err_kind(|_| {
+                        // This could mean they point to different allocations, or they point to the same allocation
+                        // but not the entire range between the pointers is in-bounds.
+                        if let Ok((a_alloc_id, ..)) = self.ptr_try_get_alloc_id(a, 0)
+                            && let Ok((b_alloc_id, ..)) = self.ptr_try_get_alloc_id(b, 0)
+                            && a_alloc_id == b_alloc_id
+                        {
+                            err_ub_custom!(
+                                fluent::const_eval_offset_from_out_of_bounds,
+                                name = intrinsic_name,
+                            )
+                        } else {
+                            err_ub_custom!(
+                                fluent::const_eval_offset_from_different_allocations,
+                                name = intrinsic_name,
+                            )
+                        }
+                    })?;
                 // Then check that this is also dereferenceable from `a`. This ensures that they are
                 // derived from the same allocation.
                 self.check_ptr_access_signed(
diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
index ecf9745b779..b44d2a01d57 100644
--- a/compiler/rustc_const_eval/src/lib.rs
+++ b/compiler/rustc_const_eval/src/lib.rs
@@ -46,14 +46,8 @@ pub fn provide(providers: &mut Providers) {
     };
     providers.hooks.try_destructure_mir_constant_for_user_output =
         const_eval::try_destructure_mir_constant_for_user_output;
-    providers.valtree_to_const_val = |tcx, cv| {
-        const_eval::valtree_to_const_value(
-            tcx,
-            ty::TypingEnv::fully_monomorphized(),
-            cv.ty,
-            cv.valtree,
-        )
-    };
+    providers.valtree_to_const_val =
+        |tcx, cv| const_eval::valtree_to_const_value(tcx, ty::TypingEnv::fully_monomorphized(), cv);
     providers.check_validity_requirement = |tcx, (init_kind, param_env_and_ty)| {
         util::check_validity_requirement(tcx, init_kind, param_env_and_ty)
     };
diff --git a/compiler/rustc_const_eval/src/util/caller_location.rs b/compiler/rustc_const_eval/src/util/caller_location.rs
index 6dd9447cf5a..e926040e9ba 100644
--- a/compiler/rustc_const_eval/src/util/caller_location.rs
+++ b/compiler/rustc_const_eval/src/util/caller_location.rs
@@ -1,7 +1,6 @@
 use rustc_hir::LangItem;
-use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::layout::LayoutOf;
-use rustc_middle::ty::{self};
+use rustc_middle::ty::{self, TyCtxt};
 use rustc_middle::{bug, mir};
 use rustc_span::Symbol;
 use tracing::trace;
@@ -48,15 +47,15 @@ fn alloc_caller_location<'tcx>(
 }
 
 pub(crate) fn const_caller_location_provider(
-    tcx: TyCtxtAt<'_>,
+    tcx: TyCtxt<'_>,
     file: Symbol,
     line: u32,
     col: u32,
 ) -> mir::ConstValue<'_> {
     trace!("const_caller_location: {}:{}:{}", file, line, col);
     let mut ecx = mk_eval_cx_to_read_const_val(
-        tcx.tcx,
-        tcx.span,
+        tcx,
+        rustc_span::DUMMY_SP, // FIXME: use a proper span here?
         ty::TypingEnv::fully_monomorphized(),
         CanAccessMutGlobal::No,
     );
diff --git a/compiler/rustc_data_structures/src/vec_cache.rs b/compiler/rustc_data_structures/src/vec_cache.rs
index eb251b587c8..2ff60ab7f36 100644
--- a/compiler/rustc_data_structures/src/vec_cache.rs
+++ b/compiler/rustc_data_structures/src/vec_cache.rs
@@ -206,6 +206,19 @@ impl SlotIndex {
     }
 }
 
+/// In-memory cache for queries whose keys are densely-numbered IDs
+/// (e.g `CrateNum`, `LocalDefId`), and can therefore be used as indices
+/// into a dense vector of cached values.
+///
+/// (As of [#124780] the underlying storage is not an actual `Vec`, but rather
+/// a series of increasingly-large buckets, for improved performance when the
+/// parallel frontend is using multiple threads.)
+///
+/// Each entry in the cache stores the query's return value (`V`), and also
+/// an associated index (`I`), which in practice is a `DepNodeIndex` used for
+/// query dependency tracking.
+///
+/// [#124780]: https://github.com/rust-lang/rust/pull/124780
 pub struct VecCache<K: Idx, V, I> {
     // Entries per bucket:
     // Bucket  0:       4096 2^12
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index 79e2d764ac5..a90e034ba4a 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -328,16 +328,20 @@ fn check_item<'tcx>(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) -> Result<()
         hir::ItemKind::TraitAlias(..) => check_trait(tcx, item),
         // `ForeignItem`s are handled separately.
         hir::ItemKind::ForeignMod { .. } => Ok(()),
-        hir::ItemKind::TyAlias(hir_ty, hir_generics) => {
-            if tcx.type_alias_is_lazy(item.owner_id) {
-                // Bounds of lazy type aliases and of eager ones that contain opaque types are respected.
-                // E.g: `type X = impl Trait;`, `type X = (impl Trait, Y);`.
-                let res = check_item_type(tcx, def_id, hir_ty.span, UnsizedHandling::Allow);
-                check_variances_for_type_defn(tcx, item, hir_generics);
-                res
-            } else {
+        hir::ItemKind::TyAlias(hir_ty, hir_generics) if tcx.type_alias_is_lazy(item.owner_id) => {
+            let res = enter_wf_checking_ctxt(tcx, item.span, def_id, |wfcx| {
+                let ty = tcx.type_of(def_id).instantiate_identity();
+                let item_ty = wfcx.normalize(hir_ty.span, Some(WellFormedLoc::Ty(def_id)), ty);
+                wfcx.register_wf_obligation(
+                    hir_ty.span,
+                    Some(WellFormedLoc::Ty(def_id)),
+                    item_ty.into(),
+                );
+                check_where_clauses(wfcx, item.span, def_id);
                 Ok(())
-            }
+            });
+            check_variances_for_type_defn(tcx, item, hir_generics);
+            res
         }
         _ => Ok(()),
     };
@@ -1276,7 +1280,6 @@ fn check_item_fn(
 
 enum UnsizedHandling {
     Forbid,
-    Allow,
     AllowIfForeignTail,
 }
 
@@ -1294,7 +1297,6 @@ fn check_item_type(
 
         let forbid_unsized = match unsized_handling {
             UnsizedHandling::Forbid => true,
-            UnsizedHandling::Allow => false,
             UnsizedHandling::AllowIfForeignTail => {
                 let tail =
                     tcx.struct_tail_for_codegen(item_ty, wfcx.infcx.typing_env(wfcx.param_env));
diff --git a/compiler/rustc_incremental/src/lib.rs b/compiler/rustc_incremental/src/lib.rs
index 6dab6468870..563ed7614c6 100644
--- a/compiler/rustc_incremental/src/lib.rs
+++ b/compiler/rustc_incremental/src/lib.rs
@@ -24,7 +24,7 @@ use rustc_middle::util::Providers;
 #[allow(missing_docs)]
 pub fn provide(providers: &mut Providers) {
     providers.hooks.save_dep_graph =
-        |tcx| tcx.sess.time("serialize_dep_graph", || persist::save_dep_graph(tcx.tcx));
+        |tcx| tcx.sess.time("serialize_dep_graph", || persist::save_dep_graph(tcx));
 }
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index 0324ebf9fd2..8a121c5a865 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -268,6 +268,7 @@ fn configure_and_expand(
 
     resolver.resolve_crate(&krate);
 
+    CStore::from_tcx(tcx).report_incompatible_target_modifiers(tcx, &krate);
     krate
 }
 
diff --git a/compiler/rustc_metadata/messages.ftl b/compiler/rustc_metadata/messages.ftl
index d2b5ae53185..6fc84b06647 100644
--- a/compiler/rustc_metadata/messages.ftl
+++ b/compiler/rustc_metadata/messages.ftl
@@ -113,6 +113,14 @@ metadata_incompatible_rustc =
     found crate `{$crate_name}` compiled by an incompatible version of rustc{$add_info}
     .help = please recompile that crate using this compiler ({$rustc_version}) (consider running `cargo clean` first)
 
+metadata_incompatible_target_modifiers =
+    mixing `{$flag_name_prefixed}` will cause an ABI mismatch in crate `{$local_crate}`
+    .note = `{$flag_name_prefixed}={$flag_local_value}` in this crate is incompatible with `{$flag_name_prefixed}={$flag_extern_value}` in dependency `{$extern_crate}`
+    .help = the `{$flag_name_prefixed}` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
+
+metadata_incompatible_target_modifiers_help_allow = if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch={$flag_name}` to silence this error
+metadata_incompatible_target_modifiers_help_fix = set `{$flag_name_prefixed}={$flag_extern_value}` in this crate or `{$flag_name_prefixed}={$flag_local_value}` in `{$extern_crate}`
+
 metadata_incompatible_wasm_link =
     `wasm_import_module` is incompatible with other arguments in `#[link]` attributes
 
@@ -284,6 +292,8 @@ metadata_unknown_link_kind =
 metadata_unknown_link_modifier =
     unknown linking modifier `{$modifier}`, expected one of: bundle, verbatim, whole-archive, as-needed
 
+metadata_unknown_target_modifier_unsafe_allowed = unknown target modifier `{$flag_name}`, requested by `-Cunsafe-allow-abi-mismatch={$flag_name}`
+
 metadata_unsupported_abi =
     ABI not supported by `#[link(kind = "raw-dylib")]` on this architecture
 
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index a6cd0ecafd0..6bad8312790 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -23,7 +23,10 @@ use rustc_hir::definitions::Definitions;
 use rustc_index::IndexVec;
 use rustc_middle::bug;
 use rustc_middle::ty::{TyCtxt, TyCtxtFeed};
-use rustc_session::config::{self, CrateType, ExternLocation};
+use rustc_session::config::{
+    self, CrateType, ExtendedTargetModifierInfo, ExternLocation, OptionsTargetModifiers,
+    TargetModifier,
+};
 use rustc_session::cstore::{CrateDepKind, CrateSource, ExternCrate, ExternCrateSource};
 use rustc_session::lint::{self, BuiltinLintDiag};
 use rustc_session::output::validate_crate_name;
@@ -35,7 +38,9 @@ use tracing::{debug, info, trace};
 
 use crate::errors;
 use crate::locator::{CrateError, CrateLocator, CratePaths};
-use crate::rmeta::{CrateDep, CrateMetadata, CrateNumMap, CrateRoot, MetadataBlob};
+use crate::rmeta::{
+    CrateDep, CrateMetadata, CrateNumMap, CrateRoot, MetadataBlob, TargetModifiers,
+};
 
 /// The backend's way to give the crate store access to the metadata in a library.
 /// Note that it returns the raw metadata bytes stored in the library file, whether
@@ -296,6 +301,94 @@ impl CStore {
         }
     }
 
+    fn report_target_modifiers_extended(
+        tcx: TyCtxt<'_>,
+        krate: &Crate,
+        mods: &TargetModifiers,
+        dep_mods: &TargetModifiers,
+        data: &CrateMetadata,
+    ) {
+        let span = krate.spans.inner_span.shrink_to_lo();
+        let allowed_flag_mismatches = &tcx.sess.opts.cg.unsafe_allow_abi_mismatch;
+        let name = tcx.crate_name(LOCAL_CRATE);
+        let tmod_extender = |tmod: &TargetModifier| (tmod.extend(), tmod.clone());
+        let report_diff = |prefix: &String,
+                           opt_name: &String,
+                           flag_local_value: &String,
+                           flag_extern_value: &String| {
+            if allowed_flag_mismatches.contains(&opt_name) {
+                return;
+            }
+            tcx.dcx().emit_err(errors::IncompatibleTargetModifiers {
+                span,
+                extern_crate: data.name(),
+                local_crate: name,
+                flag_name: opt_name.clone(),
+                flag_name_prefixed: format!("-{}{}", prefix, opt_name),
+                flag_local_value: flag_local_value.to_string(),
+                flag_extern_value: flag_extern_value.to_string(),
+            });
+        };
+        let mut it1 = mods.iter().map(tmod_extender);
+        let mut it2 = dep_mods.iter().map(tmod_extender);
+        let mut left_name_val: Option<(ExtendedTargetModifierInfo, TargetModifier)> = None;
+        let mut right_name_val: Option<(ExtendedTargetModifierInfo, TargetModifier)> = None;
+        let no_val = "*".to_string();
+        loop {
+            left_name_val = left_name_val.or_else(|| it1.next());
+            right_name_val = right_name_val.or_else(|| it2.next());
+            match (&left_name_val, &right_name_val) {
+                (Some(l), Some(r)) => match l.1.opt.cmp(&r.1.opt) {
+                    cmp::Ordering::Equal => {
+                        if l.0.tech_value != r.0.tech_value {
+                            report_diff(&l.0.prefix, &l.0.name, &l.1.value_name, &r.1.value_name);
+                        }
+                        left_name_val = None;
+                        right_name_val = None;
+                    }
+                    cmp::Ordering::Greater => {
+                        report_diff(&r.0.prefix, &r.0.name, &no_val, &r.1.value_name);
+                        right_name_val = None;
+                    }
+                    cmp::Ordering::Less => {
+                        report_diff(&l.0.prefix, &l.0.name, &l.1.value_name, &no_val);
+                        left_name_val = None;
+                    }
+                },
+                (Some(l), None) => {
+                    report_diff(&l.0.prefix, &l.0.name, &l.1.value_name, &no_val);
+                    left_name_val = None;
+                }
+                (None, Some(r)) => {
+                    report_diff(&r.0.prefix, &r.0.name, &no_val, &r.1.value_name);
+                    right_name_val = None;
+                }
+                (None, None) => break,
+            }
+        }
+    }
+
+    pub fn report_incompatible_target_modifiers(&self, tcx: TyCtxt<'_>, krate: &Crate) {
+        for flag_name in &tcx.sess.opts.cg.unsafe_allow_abi_mismatch {
+            if !OptionsTargetModifiers::is_target_modifier(flag_name) {
+                tcx.dcx().emit_err(errors::UnknownTargetModifierUnsafeAllowed {
+                    span: krate.spans.inner_span.shrink_to_lo(),
+                    flag_name: flag_name.clone(),
+                });
+            }
+        }
+        let mods = tcx.sess.opts.gather_target_modifiers();
+        for (_cnum, data) in self.iter_crate_data() {
+            if data.is_proc_macro_crate() {
+                continue;
+            }
+            let dep_mods = data.target_modifiers();
+            if mods != dep_mods {
+                Self::report_target_modifiers_extended(tcx, krate, &mods, &dep_mods, data);
+            }
+        }
+    }
+
     pub fn new(metadata_loader: Box<MetadataLoaderDyn>) -> CStore {
         CStore {
             metadata_loader,
diff --git a/compiler/rustc_metadata/src/errors.rs b/compiler/rustc_metadata/src/errors.rs
index cefc6498f68..a77f9bc623b 100644
--- a/compiler/rustc_metadata/src/errors.rs
+++ b/compiler/rustc_metadata/src/errors.rs
@@ -739,3 +739,28 @@ pub(crate) struct WasmCAbi {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(metadata_incompatible_target_modifiers)]
+#[help]
+#[note]
+#[help(metadata_incompatible_target_modifiers_help_fix)]
+#[help(metadata_incompatible_target_modifiers_help_allow)]
+pub struct IncompatibleTargetModifiers {
+    #[primary_span]
+    pub span: Span,
+    pub extern_crate: Symbol,
+    pub local_crate: Symbol,
+    pub flag_name: String,
+    pub flag_name_prefixed: String,
+    pub flag_local_value: String,
+    pub flag_extern_value: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(metadata_unknown_target_modifier_unsafe_allowed)]
+pub struct UnknownTargetModifierUnsafeAllowed {
+    #[primary_span]
+    pub span: Span,
+    pub flag_name: String,
+}
diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
index e02c4871f35..2ae4a6a6066 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -29,6 +29,7 @@ use rustc_middle::{bug, implement_ty_decoder};
 use rustc_serialize::opaque::MemDecoder;
 use rustc_serialize::{Decodable, Decoder};
 use rustc_session::Session;
+use rustc_session::config::TargetModifier;
 use rustc_session::cstore::{CrateSource, ExternCrate};
 use rustc_span::hygiene::HygieneDecodeContext;
 use rustc_span::{BytePos, DUMMY_SP, Pos, SpanData, SpanDecoder, SyntaxContext, kw};
@@ -73,6 +74,9 @@ impl MetadataBlob {
 /// own crate numbers.
 pub(crate) type CrateNumMap = IndexVec<CrateNum, CrateNum>;
 
+/// Target modifiers - abi or exploit mitigations flags
+pub(crate) type TargetModifiers = Vec<TargetModifier>;
+
 pub(crate) struct CrateMetadata {
     /// The primary crate data - binary metadata blob.
     blob: MetadataBlob,
@@ -961,6 +965,13 @@ impl CrateRoot {
     ) -> impl ExactSizeIterator<Item = CrateDep> + Captures<'a> {
         self.crate_deps.decode(metadata)
     }
+
+    pub(crate) fn decode_target_modifiers<'a>(
+        &self,
+        metadata: &'a MetadataBlob,
+    ) -> impl ExactSizeIterator<Item = TargetModifier> + Captures<'a> {
+        self.target_modifiers.decode(metadata)
+    }
 }
 
 impl<'a> CrateMetadataRef<'a> {
@@ -1883,6 +1894,10 @@ impl CrateMetadata {
         self.dependencies.push(cnum);
     }
 
+    pub(crate) fn target_modifiers(&self) -> TargetModifiers {
+        self.root.decode_target_modifiers(&self.blob).collect()
+    }
+
     pub(crate) fn update_extern_crate(&mut self, new_extern_crate: ExternCrate) -> bool {
         let update =
             Some(new_extern_crate.rank()) > self.extern_crate.as_ref().map(ExternCrate::rank);
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index 5fcb9c85035..028ff56155f 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -689,7 +689,7 @@ fn provide_cstore_hooks(providers: &mut Providers) {
     providers.hooks.def_path_hash_to_def_id_extern = |tcx, hash, stable_crate_id| {
         // If this is a DefPathHash from an upstream crate, let the CrateStore map
         // it to a DefId.
-        let cstore = CStore::from_tcx(tcx.tcx);
+        let cstore = CStore::from_tcx(tcx);
         let cnum = *tcx
             .untracked()
             .stable_crate_ids
@@ -702,11 +702,11 @@ fn provide_cstore_hooks(providers: &mut Providers) {
     };
 
     providers.hooks.expn_hash_to_expn_id = |tcx, cnum, index_guess, hash| {
-        let cstore = CStore::from_tcx(tcx.tcx);
+        let cstore = CStore::from_tcx(tcx);
         cstore.get_crate_data(cnum).expn_hash_to_expn_id(tcx.sess, index_guess, hash)
     };
     providers.hooks.import_source_files = |tcx, cnum| {
-        let cstore = CStore::from_tcx(tcx.tcx);
+        let cstore = CStore::from_tcx(tcx);
         let cdata = cstore.get_crate_data(cnum);
         for file_index in 0..cdata.root.source_map.size() {
             cdata.imported_source_file(file_index as u32, tcx.sess);
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 6e562e457d2..db41a33dcc5 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -25,7 +25,7 @@ use rustc_middle::ty::fast_reject::{self, TreatParams};
 use rustc_middle::ty::{AssocItemContainer, SymbolName};
 use rustc_middle::{bug, span_bug};
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder, opaque};
-use rustc_session::config::{CrateType, OptLevel};
+use rustc_session::config::{CrateType, OptLevel, TargetModifier};
 use rustc_span::hygiene::HygieneEncodeContext;
 use rustc_span::{
     ExternalSource, FileName, SourceFile, SpanData, SpanEncoder, StableSourceFileId, SyntaxContext,
@@ -692,6 +692,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         // Encode source_map. This needs to be done last, because encoding `Span`s tells us which
         // `SourceFiles` we actually need to encode.
         let source_map = stat!("source-map", || self.encode_source_map());
+        let target_modifiers = stat!("target-modifiers", || self.encode_target_modifiers());
 
         let root = stat!("final", || {
             let attrs = tcx.hir().krate_attrs();
@@ -735,6 +736,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 native_libraries,
                 foreign_modules,
                 source_map,
+                target_modifiers,
                 traits,
                 impls,
                 incoherent_impls,
@@ -2009,6 +2011,12 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         self.lazy_array(deps.iter().map(|(_, dep)| dep))
     }
 
+    fn encode_target_modifiers(&mut self) -> LazyArray<TargetModifier> {
+        empty_proc_macro!(self);
+        let tcx = self.tcx;
+        self.lazy_array(tcx.sess.opts.gather_target_modifiers())
+    }
+
     fn encode_lib_features(&mut self) -> LazyArray<(Symbol, FeatureStability)> {
         empty_proc_macro!(self);
         let tcx = self.tcx;
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index d1d356c5220..7b34e605c53 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -1,7 +1,7 @@
 use std::marker::PhantomData;
 use std::num::NonZero;
 
-pub(crate) use decoder::{CrateMetadata, CrateNumMap, MetadataBlob};
+pub(crate) use decoder::{CrateMetadata, CrateNumMap, MetadataBlob, TargetModifiers};
 use decoder::{DecodeContext, Metadata};
 use def_path_hash_map::DefPathHashMapRef;
 use encoder::EncodeContext;
@@ -32,7 +32,7 @@ use rustc_middle::ty::{
 use rustc_middle::util::Providers;
 use rustc_middle::{mir, trivially_parameterized_over_tcx};
 use rustc_serialize::opaque::FileEncoder;
-use rustc_session::config::SymbolManglingVersion;
+use rustc_session::config::{SymbolManglingVersion, TargetModifier};
 use rustc_session::cstore::{CrateDepKind, ForeignModule, LinkagePreference, NativeLib};
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::{ExpnIndex, MacroKind, SyntaxContextData};
@@ -282,6 +282,7 @@ pub(crate) struct CrateRoot {
     def_path_hash_map: LazyValue<DefPathHashMapRef<'static>>,
 
     source_map: LazyTable<u32, Option<LazyValue<rustc_span::SourceFile>>>,
+    target_modifiers: LazyArray<TargetModifier>,
 
     compiler_builtins: bool,
     needs_allocator: bool,
diff --git a/compiler/rustc_middle/src/hooks/mod.rs b/compiler/rustc_middle/src/hooks/mod.rs
index 2be242364c1..276a02b4e0f 100644
--- a/compiler/rustc_middle/src/hooks/mod.rs
+++ b/compiler/rustc_middle/src/hooks/mod.rs
@@ -6,11 +6,9 @@
 use rustc_hir::def_id::{DefId, DefPathHash};
 use rustc_session::StableCrateId;
 use rustc_span::def_id::{CrateNum, LocalDefId};
-use rustc_span::{DUMMY_SP, ExpnHash, ExpnId};
-use tracing::instrument;
+use rustc_span::{ExpnHash, ExpnId};
 
 use crate::mir;
-use crate::query::TyCtxtAt;
 use crate::ty::{Ty, TyCtxt};
 
 macro_rules! declare_hooks {
@@ -22,26 +20,14 @@ macro_rules! declare_hooks {
             #[inline(always)]
             pub fn $name(self, $($arg: $K,)*) -> $V
             {
-                self.at(DUMMY_SP).$name($($arg,)*)
-            }
-            )*
-        }
-
-        impl<'tcx> TyCtxtAt<'tcx> {
-            $(
-            $(#[$attr])*
-            #[inline(always)]
-            #[instrument(level = "debug", skip(self), ret)]
-            pub fn $name(self, $($arg: $K,)*) -> $V
-            {
-                (self.tcx.hooks.$name)(self, $($arg,)*)
+                (self.hooks.$name)(self, $($arg,)*)
             }
             )*
         }
 
         pub struct Providers {
             $(pub $name: for<'tcx> fn(
-                TyCtxtAt<'tcx>,
+                TyCtxt<'tcx>,
                 $($arg: $K,)*
             ) -> $V,)*
         }
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 09d7e60e199..aa8ec3aff04 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -12,6 +12,7 @@ use rustc_middle::mir::interpret::{
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::*;
 use tracing::trace;
+use ty::print::PrettyPrinter;
 
 use super::graphviz::write_mir_fn_graphviz;
 use crate::mir::interpret::ConstAllocation;
@@ -1439,10 +1440,10 @@ impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
                 })
             };
 
-            // FIXME: call pretty_print_const_valtree?
-            let fmt_valtree = |valtree: &ty::ValTree<'tcx>| match valtree {
-                ty::ValTree::Leaf(leaf) => format!("Leaf({leaf:?})"),
-                ty::ValTree::Branch(_) => "Branch(..)".to_string(),
+            let fmt_valtree = |cv: &ty::Value<'tcx>| {
+                let mut cx = FmtPrinter::new(self.tcx, Namespace::ValueNS);
+                cx.pretty_print_const_valtree(*cv, /*print_ty*/ true).unwrap();
+                cx.into_buffer()
             };
 
             let val = match const_ {
@@ -1452,7 +1453,7 @@ impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
                         format!("ty::Unevaluated({}, {:?})", self.tcx.def_path_str(uv.def), uv.args,)
                     }
                     ty::ConstKind::Value(cv) => {
-                        format!("ty::Valtree({})", fmt_valtree(&cv.valtree))
+                        format!("ty::Valtree({})", fmt_valtree(&cv))
                     }
                     // No `ty::` prefix since we also use this to represent errors from `mir::Unevaluated`.
                     ty::ConstKind::Error(_) => "Error".to_string(),
diff --git a/compiler/rustc_middle/src/query/keys.rs b/compiler/rustc_middle/src/query/keys.rs
index 949d8303385..1489d57aba6 100644
--- a/compiler/rustc_middle/src/query/keys.rs
+++ b/compiler/rustc_middle/src/query/keys.rs
@@ -20,6 +20,12 @@ pub struct LocalCrate;
 /// The `Key` trait controls what types can legally be used as the key
 /// for a query.
 pub trait Key: Sized {
+    /// The type of in-memory cache to use for queries with this key type.
+    ///
+    /// In practice the cache type must implement [`QueryCache`], though that
+    /// constraint is not enforced here.
+    ///
+    /// [`QueryCache`]: rustc_query_system::query::QueryCache
     // N.B. Most of the keys down below have `type Cache<V> = DefaultCache<Self, V>;`,
     //      it would be reasonable to use associated type defaults, to remove the duplication...
     //
diff --git a/compiler/rustc_middle/src/thir.rs b/compiler/rustc_middle/src/thir.rs
index d56046136c7..5490f1f53ea 100644
--- a/compiler/rustc_middle/src/thir.rs
+++ b/compiler/rustc_middle/src/thir.rs
@@ -18,7 +18,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::{BindingMode, ByRef, HirId, MatchSource, RangeEnd};
 use rustc_index::{IndexVec, newtype_index};
-use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeVisitable};
+use rustc_macros::{HashStable, TypeVisitable};
 use rustc_middle::middle::region;
 use rustc_middle::mir::interpret::AllocId;
 use rustc_middle::mir::{self, BinOp, BorrowKind, FakeReadCause, UnOp};
@@ -53,7 +53,7 @@ macro_rules! thir_with_elements {
         /// A container for a THIR body.
         ///
         /// This can be indexed directly by any THIR index (e.g. [`ExprId`]).
-        #[derive(Debug, HashStable, Clone)]
+        #[derive(Debug, HashStable)]
         pub struct Thir<'tcx> {
             $(
                 pub $field_name: $field_ty,
@@ -98,14 +98,14 @@ thir_with_elements! {
     params: ParamId => Param<'tcx> => "p{}",
 }
 
-#[derive(Debug, HashStable, Clone)]
+#[derive(Debug, HashStable)]
 pub enum BodyTy<'tcx> {
     Const(Ty<'tcx>),
     Fn(FnSig<'tcx>),
 }
 
 /// Description of a type-checked function parameter.
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct Param<'tcx> {
     /// The pattern that appears in the parameter list, or None for implicit parameters.
     pub pat: Option<Box<Pat<'tcx>>>,
@@ -125,7 +125,7 @@ pub enum LintLevel {
     Explicit(HirId),
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct Block {
     /// Whether the block itself has a label. Used by `label: {}`
     /// and `try` blocks.
@@ -145,7 +145,7 @@ pub struct Block {
 
 type UserTy<'tcx> = Option<Box<CanonicalUserType<'tcx>>>;
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct AdtExpr<'tcx> {
     /// The ADT we're constructing.
     pub adt_def: AdtDef<'tcx>,
@@ -162,7 +162,7 @@ pub struct AdtExpr<'tcx> {
     pub base: AdtExprBase<'tcx>,
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub enum AdtExprBase<'tcx> {
     /// A struct expression where all the fields are explicitly enumerated: `Foo { a, b }`.
     None,
@@ -175,7 +175,7 @@ pub enum AdtExprBase<'tcx> {
     DefaultFields(Box<[Ty<'tcx>]>),
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct ClosureExpr<'tcx> {
     pub closure_id: LocalDefId,
     pub args: UpvarArgs<'tcx>,
@@ -184,7 +184,7 @@ pub struct ClosureExpr<'tcx> {
     pub fake_reads: Vec<(ExprId, FakeReadCause, HirId)>,
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct InlineAsmExpr<'tcx> {
     pub asm_macro: AsmMacro,
     pub template: &'tcx [InlineAsmTemplatePiece],
@@ -202,12 +202,12 @@ pub enum BlockSafety {
     ExplicitUnsafe(HirId),
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct Stmt<'tcx> {
     pub kind: StmtKind<'tcx>,
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub enum StmtKind<'tcx> {
     /// An expression with a trailing semicolon.
     Expr {
@@ -247,11 +247,11 @@ pub enum StmtKind<'tcx> {
     },
 }
 
-#[derive(Clone, Debug, Copy, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, HashStable)]
 pub struct LocalVarId(pub HirId);
 
 /// A THIR expression.
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct Expr<'tcx> {
     /// kind of expression
     pub kind: ExprKind<'tcx>,
@@ -278,7 +278,7 @@ pub struct TempLifetime {
     pub backwards_incompatible: Option<region::Scope>,
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub enum ExprKind<'tcx> {
     /// `Scope`s are used to explicitly mark destruction scopes,
     /// and to track the `HirId` of the expressions within the scope.
@@ -556,20 +556,20 @@ pub enum ExprKind<'tcx> {
 /// Represents the association of a field identifier and an expression.
 ///
 /// This is used in struct constructors.
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct FieldExpr {
     pub name: FieldIdx,
     pub expr: ExprId,
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct FruInfo<'tcx> {
     pub base: ExprId,
     pub field_types: Box<[Ty<'tcx>]>,
 }
 
 /// A `match` arm.
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub struct Arm<'tcx> {
     pub pattern: Box<Pat<'tcx>>,
     pub guard: Option<ExprId>,
@@ -587,7 +587,7 @@ pub enum LogicalOp {
     Or,
 }
 
-#[derive(Clone, Debug, HashStable)]
+#[derive(Debug, HashStable)]
 pub enum InlineAsmOperand<'tcx> {
     In {
         reg: InlineAsmRegOrRegClass,
@@ -625,13 +625,13 @@ pub enum InlineAsmOperand<'tcx> {
     },
 }
 
-#[derive(Clone, Debug, HashStable, TypeVisitable)]
+#[derive(Debug, HashStable, TypeVisitable)]
 pub struct FieldPat<'tcx> {
     pub field: FieldIdx,
     pub pattern: Box<Pat<'tcx>>,
 }
 
-#[derive(Clone, Debug, HashStable, TypeVisitable)]
+#[derive(Debug, HashStable, TypeVisitable)]
 pub struct Pat<'tcx> {
     pub ty: Ty<'tcx>,
     pub span: Span,
@@ -739,7 +739,7 @@ impl<'tcx> Pat<'tcx> {
     }
 }
 
-#[derive(Clone, Debug, HashStable, TypeVisitable)]
+#[derive(Debug, HashStable, TypeVisitable)]
 pub struct Ascription<'tcx> {
     pub annotation: CanonicalUserTypeAnnotation<'tcx>,
     /// Variance to use when relating the `user_ty` to the **type of the value being
@@ -763,7 +763,7 @@ pub struct Ascription<'tcx> {
     pub variance: ty::Variance,
 }
 
-#[derive(Clone, Debug, HashStable, TypeVisitable)]
+#[derive(Debug, HashStable, TypeVisitable)]
 pub enum PatKind<'tcx> {
     /// A wildcard pattern: `_`.
     Wild,
diff --git a/compiler/rustc_middle/src/ty/consts/valtree.rs b/compiler/rustc_middle/src/ty/consts/valtree.rs
index d914b7576dc..5905076c4d0 100644
--- a/compiler/rustc_middle/src/ty/consts/valtree.rs
+++ b/compiler/rustc_middle/src/ty/consts/valtree.rs
@@ -78,30 +78,6 @@ impl<'tcx> ValTree<'tcx> {
             Self::Branch(_) => None,
         }
     }
-
-    /// Get the values inside the ValTree as a slice of bytes. This only works for
-    /// constants with types &str, &[u8], or [u8; _].
-    pub fn try_to_raw_bytes(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Option<&'tcx [u8]> {
-        match ty.kind() {
-            ty::Ref(_, inner_ty, _) => match inner_ty.kind() {
-                // `&str` can be interpreted as raw bytes
-                ty::Str => {}
-                // `&[u8]` can be interpreted as raw bytes
-                ty::Slice(slice_ty) if *slice_ty == tcx.types.u8 => {}
-                // other `&_` can't be interpreted as raw bytes
-                _ => return None,
-            },
-            // `[u8; N]` can be interpreted as raw bytes
-            ty::Array(array_ty, _) if *array_ty == tcx.types.u8 => {}
-            // Otherwise, type cannot be interpreted as raw bytes
-            _ => return None,
-        }
-
-        Some(
-            tcx.arena
-                .alloc_from_iter(self.unwrap_branch().into_iter().map(|v| v.unwrap_leaf().to_u8())),
-        )
-    }
 }
 
 /// A type-level constant value.
@@ -143,6 +119,29 @@ impl<'tcx> Value<'tcx> {
         }
         self.valtree.try_to_scalar_int().map(|s| s.to_target_usize(tcx))
     }
+
+    /// Get the values inside the ValTree as a slice of bytes. This only works for
+    /// constants with types &str, &[u8], or [u8; _].
+    pub fn try_to_raw_bytes(self, tcx: TyCtxt<'tcx>) -> Option<&'tcx [u8]> {
+        match self.ty.kind() {
+            ty::Ref(_, inner_ty, _) => match inner_ty.kind() {
+                // `&str` can be interpreted as raw bytes
+                ty::Str => {}
+                // `&[u8]` can be interpreted as raw bytes
+                ty::Slice(slice_ty) if *slice_ty == tcx.types.u8 => {}
+                // other `&_` can't be interpreted as raw bytes
+                _ => return None,
+            },
+            // `[u8; N]` can be interpreted as raw bytes
+            ty::Array(array_ty, _) if *array_ty == tcx.types.u8 => {}
+            // Otherwise, type cannot be interpreted as raw bytes
+            _ => return None,
+        }
+
+        Some(tcx.arena.alloc_from_iter(
+            self.valtree.unwrap_branch().into_iter().map(|v| v.unwrap_leaf().to_u8()),
+        ))
+    }
 }
 
 impl<'tcx> rustc_type_ir::inherent::ValueConst<TyCtxt<'tcx>> for Value<'tcx> {
diff --git a/compiler/rustc_middle/src/ty/parameterized.rs b/compiler/rustc_middle/src/ty/parameterized.rs
index 6b6c6f3c72f..8eaf0a58f70 100644
--- a/compiler/rustc_middle/src/ty/parameterized.rs
+++ b/compiler/rustc_middle/src/ty/parameterized.rs
@@ -101,6 +101,7 @@ trivially_parameterized_over_tcx! {
     rustc_session::cstore::ForeignModule,
     rustc_session::cstore::LinkagePreference,
     rustc_session::cstore::NativeLib,
+    rustc_session::config::TargetModifier,
     rustc_span::ExpnData,
     rustc_span::ExpnHash,
     rustc_span::ExpnId,
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 6c8591dae89..3431081b189 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1487,7 +1487,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             },
             ty::ConstKind::Param(ParamConst { name, .. }) => p!(write("{}", name)),
             ty::ConstKind::Value(cv) => {
-                return self.pretty_print_const_valtree(cv.valtree, cv.ty, print_ty);
+                return self.pretty_print_const_valtree(cv, print_ty);
             }
 
             ty::ConstKind::Bound(debruijn, bound_var) => {
@@ -1787,48 +1787,47 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         Ok(())
     }
 
-    // FIXME(valtrees): Accept `ty::Value` instead of `Ty` and `ty::ValTree` separately.
     fn pretty_print_const_valtree(
         &mut self,
-        valtree: ty::ValTree<'tcx>,
-        ty: Ty<'tcx>,
+        cv: ty::Value<'tcx>,
         print_ty: bool,
     ) -> Result<(), PrintError> {
         define_scoped_cx!(self);
 
         if self.should_print_verbose() {
-            p!(write("ValTree({:?}: ", valtree), print(ty), ")");
+            p!(write("ValTree({:?}: ", cv.valtree), print(cv.ty), ")");
             return Ok(());
         }
 
         let u8_type = self.tcx().types.u8;
-        match (valtree, ty.kind()) {
+        match (cv.valtree, cv.ty.kind()) {
             (ty::ValTree::Branch(_), ty::Ref(_, inner_ty, _)) => match inner_ty.kind() {
                 ty::Slice(t) if *t == u8_type => {
-                    let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
+                    let bytes = cv.try_to_raw_bytes(self.tcx()).unwrap_or_else(|| {
                         bug!(
                             "expected to convert valtree {:?} to raw bytes for type {:?}",
-                            valtree,
+                            cv.valtree,
                             t
                         )
                     });
                     return self.pretty_print_byte_str(bytes);
                 }
                 ty::Str => {
-                    let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
-                        bug!("expected to convert valtree to raw bytes for type {:?}", ty)
+                    let bytes = cv.try_to_raw_bytes(self.tcx()).unwrap_or_else(|| {
+                        bug!("expected to convert valtree to raw bytes for type {:?}", cv.ty)
                     });
                     p!(write("{:?}", String::from_utf8_lossy(bytes)));
                     return Ok(());
                 }
                 _ => {
+                    let cv = ty::Value { valtree: cv.valtree, ty: *inner_ty };
                     p!("&");
-                    p!(pretty_print_const_valtree(valtree, *inner_ty, print_ty));
+                    p!(pretty_print_const_valtree(cv, print_ty));
                     return Ok(());
                 }
             },
             (ty::ValTree::Branch(_), ty::Array(t, _)) if *t == u8_type => {
-                let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
+                let bytes = cv.try_to_raw_bytes(self.tcx()).unwrap_or_else(|| {
                     bug!("expected to convert valtree to raw bytes for type {:?}", t)
                 });
                 p!("*");
@@ -1837,10 +1836,13 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             }
             // Aggregates, printed as array/tuple/struct/variant construction syntax.
             (ty::ValTree::Branch(_), ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) => {
-                let contents =
-                    self.tcx().destructure_const(ty::Const::new_value(self.tcx(), valtree, ty));
+                let contents = self.tcx().destructure_const(ty::Const::new_value(
+                    self.tcx(),
+                    cv.valtree,
+                    cv.ty,
+                ));
                 let fields = contents.fields.iter().copied();
-                match *ty.kind() {
+                match *cv.ty.kind() {
                     ty::Array(..) => {
                         p!("[", comma_sep(fields), "]");
                     }
@@ -1857,7 +1859,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                                 write!(this, "unreachable()")?;
                                 Ok(())
                             },
-                            |this| this.print_type(ty),
+                            |this| this.print_type(cv.ty),
                             ": ",
                         )?;
                     }
@@ -1894,7 +1896,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                 return self.pretty_print_const_scalar_int(leaf, *inner_ty, print_ty);
             }
             (ty::ValTree::Leaf(leaf), _) => {
-                return self.pretty_print_const_scalar_int(leaf, ty, print_ty);
+                return self.pretty_print_const_scalar_int(leaf, cv.ty, print_ty);
             }
             // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
             // their fields instead of just dumping the memory.
@@ -1902,13 +1904,13 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         }
 
         // fallback
-        if valtree == ty::ValTree::zst() {
+        if cv.valtree == ty::ValTree::zst() {
             p!(write("<ZST>"));
         } else {
-            p!(write("{:?}", valtree));
+            p!(write("{:?}", cv.valtree));
         }
         if print_ty {
-            p!(": ", print(ty));
+            p!(": ", print(cv.ty));
         }
         Ok(())
     }
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 9e9de4fb064..03b26b44538 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -170,7 +170,7 @@ impl<'tcx> fmt::Debug for ty::Const<'tcx> {
                     bug!("we checked that this is a valtree")
                 };
                 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
-                cx.pretty_print_const_valtree(cv.valtree, cv.ty, /*print_ty*/ true)?;
+                cx.pretty_print_const_valtree(cv, /*print_ty*/ true)?;
                 f.write_str(&cx.into_buffer())
             });
         }
diff --git a/compiler/rustc_mir_build/src/check_tail_calls.rs b/compiler/rustc_mir_build/src/check_tail_calls.rs
index 0659e3ea314..921205428db 100644
--- a/compiler/rustc_mir_build/src/check_tail_calls.rs
+++ b/compiler/rustc_mir_build/src/check_tail_calls.rs
@@ -1,4 +1,5 @@
 use rustc_abi::ExternAbi;
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::Applicability;
 use rustc_hir::LangItem;
 use rustc_hir::def::DefKind;
@@ -344,12 +345,14 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for TailCallCkVisitor<'a, 'tcx> {
     }
 
     fn visit_expr(&mut self, expr: &'a Expr<'tcx>) {
-        if let ExprKind::Become { value } = expr.kind {
-            let call = &self.thir[value];
-            self.check_tail_call(call, expr);
-        }
+        ensure_sufficient_stack(|| {
+            if let ExprKind::Become { value } = expr.kind {
+                let call = &self.thir[value];
+                self.check_tail_call(call, expr);
+            }
 
-        visit::walk_expr(self, expr);
+            visit::walk_expr(self, expr);
+        });
     }
 }
 
diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index e47c14b8bfa..b6494173b0f 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -2,6 +2,7 @@ use std::borrow::Cow;
 use std::mem;
 use std::ops::Bound;
 
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::DiagArgValue;
 use rustc_hir::def::DefKind;
 use rustc_hir::{self as hir, BindingMode, ByRef, HirId, Mutability};
@@ -476,7 +477,9 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
             ExprKind::Scope { value, lint_level: LintLevel::Explicit(hir_id), region_scope: _ } => {
                 let prev_id = self.hir_context;
                 self.hir_context = hir_id;
-                self.visit_expr(&self.thir[value]);
+                ensure_sufficient_stack(|| {
+                    self.visit_expr(&self.thir[value]);
+                });
                 self.hir_context = prev_id;
                 return; // don't visit the whole expression
             }
diff --git a/compiler/rustc_mir_transform/src/coverage/query.rs b/compiler/rustc_mir_transform/src/coverage/query.rs
index 5e7b46182dc..a849ed4c3e2 100644
--- a/compiler/rustc_mir_transform/src/coverage/query.rs
+++ b/compiler/rustc_mir_transform/src/coverage/query.rs
@@ -6,7 +6,6 @@ use rustc_middle::mir::coverage::{
     FunctionCoverageInfo, MappingKind, Op,
 };
 use rustc_middle::mir::{Body, Statement, StatementKind};
-use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_middle::util::Providers;
 use rustc_span::def_id::LocalDefId;
@@ -15,8 +14,7 @@ use tracing::trace;
 
 /// Registers query/hook implementations related to coverage.
 pub(crate) fn provide(providers: &mut Providers) {
-    providers.hooks.is_eligible_for_coverage =
-        |TyCtxtAt { tcx, .. }, def_id| is_eligible_for_coverage(tcx, def_id);
+    providers.hooks.is_eligible_for_coverage = is_eligible_for_coverage;
     providers.queries.coverage_attr_on = coverage_attr_on;
     providers.queries.coverage_ids_info = coverage_ids_info;
 }
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index de8a20c5dee..ae31ed59391 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -953,7 +953,7 @@ fn visit_instance_use<'tcx>(
 
 /// Returns `true` if we should codegen an instance in the local crate, or returns `false` if we
 /// can just link to the upstream crate and therefore don't need a mono item.
-fn should_codegen_locally<'tcx>(tcx: TyCtxtAt<'tcx>, instance: Instance<'tcx>) -> bool {
+fn should_codegen_locally<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) -> bool {
     let Some(def_id) = instance.def.def_id_if_not_guaranteed_local_codegen() else {
         return true;
     };
@@ -976,7 +976,7 @@ fn should_codegen_locally<'tcx>(tcx: TyCtxtAt<'tcx>, instance: Instance<'tcx>) -
         return true;
     }
 
-    if tcx.is_reachable_non_generic(def_id) || instance.upstream_monomorphization(*tcx).is_some() {
+    if tcx.is_reachable_non_generic(def_id) || instance.upstream_monomorphization(tcx).is_some() {
         // We can link to the item in question, no instance needed in this crate.
         return false;
     }
diff --git a/compiler/rustc_monomorphize/src/partitioning.rs b/compiler/rustc_monomorphize/src/partitioning.rs
index c985ea04278..3ef061195da 100644
--- a/compiler/rustc_monomorphize/src/partitioning.rs
+++ b/compiler/rustc_monomorphize/src/partitioning.rs
@@ -1179,23 +1179,23 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitio
         }
     }
 
+    #[cfg(not(llvm_enzyme))]
+    let autodiff_mono_items: Vec<_> = vec![];
+    #[cfg(llvm_enzyme)]
+    let mut autodiff_mono_items: Vec<_> = vec![];
     let mono_items: DefIdSet = items
         .iter()
         .filter_map(|mono_item| match *mono_item {
-            MonoItem::Fn(ref instance) => Some(instance.def_id()),
+            MonoItem::Fn(ref instance) => {
+                #[cfg(llvm_enzyme)]
+                autodiff_mono_items.push((mono_item, instance));
+                Some(instance.def_id())
+            }
             MonoItem::Static(def_id) => Some(def_id),
             _ => None,
         })
         .collect();
 
-    let autodiff_mono_items: Vec<_> = items
-        .iter()
-        .filter_map(|item| match *item {
-            MonoItem::Fn(ref instance) => Some((item, instance)),
-            _ => None,
-        })
-        .collect();
-
     let autodiff_items =
         autodiff::find_autodiff_source_functions(tcx, &usage_map, autodiff_mono_items);
     let autodiff_items = tcx.arena.alloc_from_iter(autodiff_items);
diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index d2bb0b3f277..bbc83cca99d 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -224,7 +224,6 @@ pub fn query_system<'a>(
 rustc_middle::rustc_query_append! { define_queries! }
 
 pub fn provide(providers: &mut rustc_middle::util::Providers) {
-    providers.hooks.alloc_self_profile_query_strings =
-        |tcx| alloc_self_profile_query_strings(tcx.tcx);
-    providers.hooks.query_key_hash_verify_all = |tcx| query_key_hash_verify_all(tcx.tcx);
+    providers.hooks.alloc_self_profile_query_strings = alloc_self_profile_query_strings;
+    providers.hooks.query_key_hash_verify_all = query_key_hash_verify_all;
 }
diff --git a/compiler/rustc_query_system/src/query/caches.rs b/compiler/rustc_query_system/src/query/caches.rs
index e6f3d97742d..e11123dff26 100644
--- a/compiler/rustc_query_system/src/query/caches.rs
+++ b/compiler/rustc_query_system/src/query/caches.rs
@@ -11,18 +11,30 @@ use rustc_span::def_id::{DefId, DefIndex};
 
 use crate::dep_graph::DepNodeIndex;
 
+/// Trait for types that serve as an in-memory cache for query results,
+/// for a given key (argument) type and value (return) type.
+///
+/// Types implementing this trait are associated with actual key/value types
+/// by the `Cache` associated type of the `rustc_middle::query::Key` trait.
 pub trait QueryCache: Sized {
     type Key: Hash + Eq + Copy + Debug;
     type Value: Copy;
 
-    /// Checks if the query is already computed and in the cache.
+    /// Returns the cached value (and other information) associated with the
+    /// given key, if it is present in the cache.
     fn lookup(&self, key: &Self::Key) -> Option<(Self::Value, DepNodeIndex)>;
 
+    /// Adds a key/value entry to this cache.
+    ///
+    /// Called by some part of the query system, after having obtained the
+    /// value by executing the query or loading a cached value from disk.
     fn complete(&self, key: Self::Key, value: Self::Value, index: DepNodeIndex);
 
     fn iter(&self, f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex));
 }
 
+/// In-memory cache for queries whose keys aren't suitable for any of the
+/// more specialized kinds of cache. Backed by a sharded hashmap.
 pub struct DefaultCache<K, V> {
     cache: Sharded<FxHashMap<K, (V, DepNodeIndex)>>,
 }
@@ -67,6 +79,8 @@ where
     }
 }
 
+/// In-memory cache for queries whose key type only has one value (e.g. `()`).
+/// The cache therefore only needs to store one query return value.
 pub struct SingleCache<V> {
     cache: OnceLock<(V, DepNodeIndex)>,
 }
@@ -101,6 +115,10 @@ where
     }
 }
 
+/// In-memory cache for queries whose key is a [`DefId`].
+///
+/// Selects between one of two internal caches, depending on whether the key
+/// is a local ID or foreign-crate ID.
 pub struct DefIdCache<V> {
     /// Stores the local DefIds in a dense map. Local queries are much more often dense, so this is
     /// a win over hashing query keys at marginal memory cost (~5% at most) compared to FxHashMap.
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index 6fb5e37d2d0..18aae8c00b2 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -222,10 +222,10 @@ pub struct CycleError {
     pub cycle: Vec<QueryInfo>,
 }
 
-/// Checks if the query is already computed and in the cache.
-/// It returns the shard index and a lock guard to the shard,
-/// which will be used if the query is not in the cache and we need
-/// to compute it.
+/// Checks whether there is already a value for this key in the in-memory
+/// query cache, returning that value if present.
+///
+/// (Also performs some associated bookkeeping, if a value was found.)
 #[inline(always)]
 pub fn try_get_cached<Tcx, C>(tcx: Tcx, cache: &C, key: &C::Key) -> Option<C::Value>
 where
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 67e314cc685..2fb4b27b889 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -1224,6 +1224,7 @@ impl Default for Options {
             color: ColorConfig::Auto,
             logical_env: FxIndexMap::default(),
             verbose: false,
+            target_modifiers: BTreeMap::default(),
         }
     }
 }
@@ -2370,14 +2371,16 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
     let crate_types = parse_crate_types_from_list(unparsed_crate_types)
         .unwrap_or_else(|e| early_dcx.early_fatal(e));
 
-    let mut unstable_opts = UnstableOptions::build(early_dcx, matches);
+    let mut target_modifiers = BTreeMap::<OptionsTargetModifiers, String>::new();
+
+    let mut unstable_opts = UnstableOptions::build(early_dcx, matches, &mut target_modifiers);
     let (lint_opts, describe_lints, lint_cap) = get_cmd_lint_options(early_dcx, matches);
 
     check_error_format_stability(early_dcx, &unstable_opts, error_format);
 
     let output_types = parse_output_types(early_dcx, &unstable_opts, matches);
 
-    let mut cg = CodegenOptions::build(early_dcx, matches);
+    let mut cg = CodegenOptions::build(early_dcx, matches, &mut target_modifiers);
     let (disable_local_thinlto, codegen_units) = should_override_cgus_and_disable_thinlto(
         early_dcx,
         &output_types,
@@ -2648,6 +2651,7 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         color,
         logical_env,
         verbose,
+        target_modifiers,
     }
 }
 
diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index dcf86d1a408..924350b8cbc 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -4,6 +4,9 @@
 #![feature(let_chains)]
 #![feature(map_many_mut)]
 #![feature(rustc_attrs)]
+// To generate CodegenOptionsTargetModifiers and UnstableOptionsTargetModifiers enums
+// with macro_rules, it is necessary to use recursive mechanic ("Incremental TT Munchers").
+#![recursion_limit = "256"]
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index cc86c85f3f0..4ed5499d32c 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -10,6 +10,7 @@ use rustc_data_structures::profiling::TimePassesFormat;
 use rustc_data_structures::stable_hasher::Hash64;
 use rustc_errors::{ColorConfig, LanguageIdentifier, TerminalUrl};
 use rustc_feature::UnstableFeatures;
+use rustc_macros::{Decodable, Encodable};
 use rustc_span::edition::Edition;
 use rustc_span::{RealFileName, SourceFileHashAlgorithm};
 use rustc_target::spec::{
@@ -59,18 +60,194 @@ macro_rules! hash_substruct {
     };
 }
 
+/// Extended target modifier info.
+/// For example, when external target modifier is '-Zregparm=2':
+/// Target modifier enum value + user value ('2') from external crate
+/// is converted into description: prefix ('Z'), name ('regparm'), tech value ('Some(2)').
+pub struct ExtendedTargetModifierInfo {
+    /// Flag prefix (usually, 'C' for codegen flags or 'Z' for unstable flags)
+    pub prefix: String,
+    /// Flag name
+    pub name: String,
+    /// Flag parsed technical value
+    pub tech_value: String,
+}
+
+/// A recorded -Zopt_name=opt_value (or -Copt_name=opt_value)
+/// which alter the ABI or effectiveness of exploit mitigations.
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Encodable, Decodable)]
+pub struct TargetModifier {
+    /// Option enum value
+    pub opt: OptionsTargetModifiers,
+    /// User-provided option value (before parsing)
+    pub value_name: String,
+}
+
+impl TargetModifier {
+    pub fn extend(&self) -> ExtendedTargetModifierInfo {
+        self.opt.reparse(&self.value_name)
+    }
+}
+
+fn tmod_push_impl(
+    opt: OptionsTargetModifiers,
+    tmod_vals: &BTreeMap<OptionsTargetModifiers, String>,
+    tmods: &mut Vec<TargetModifier>,
+) {
+    tmods.push(TargetModifier { opt, value_name: tmod_vals.get(&opt).cloned().unwrap_or_default() })
+}
+
+macro_rules! tmod_push {
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $mods:expr, $tmod_vals:expr) => {
+        tmod_push_impl(
+            OptionsTargetModifiers::$struct_name($tmod_enum_name::$opt_name),
+            $tmod_vals,
+            $mods,
+        );
+    };
+}
+
+macro_rules! gather_tmods {
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+        [SUBSTRUCT], [TARGET_MODIFIER]) => {
+        compile_error!("SUBSTRUCT can't be target modifier");
+    };
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+        [UNTRACKED], [TARGET_MODIFIER]) => {
+        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $mods, $tmod_vals)
+    };
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+        [TRACKED], [TARGET_MODIFIER]) => {
+        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $mods, $tmod_vals)
+    };
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+        [TRACKED_NO_CRATE_HASH], [TARGET_MODIFIER]) => {
+        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $mods, $tmod_vals)
+    };
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+        [SUBSTRUCT], []) => {
+        $opt_expr.gather_target_modifiers($mods, $tmod_vals);
+    };
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+        [UNTRACKED], []) => {{}};
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+        [TRACKED], []) => {{}};
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+        [TRACKED_NO_CRATE_HASH], []) => {{}};
+}
+
+macro_rules! gather_tmods_top_level {
+    ($_opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr, [SUBSTRUCT $substruct_enum:ident]) => {
+        $opt_expr.gather_target_modifiers($mods, $tmod_vals);
+    };
+    ($opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr, [$non_substruct:ident TARGET_MODIFIER]) => {
+        compile_error!("Top level option can't be target modifier");
+    };
+    ($opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr, [$non_substruct:ident]) => {};
+}
+
+/// Macro for generating OptionsTargetsModifiers top-level enum with impl.
+/// Will generate something like:
+/// ```rust,ignore (illustrative)
+/// pub enum OptionsTargetModifiers {
+///     CodegenOptions(CodegenOptionsTargetModifiers),
+///     UnstableOptions(UnstableOptionsTargetModifiers),
+/// }
+/// impl OptionsTargetModifiers {
+///     pub fn reparse(&self, user_value: &str) -> ExtendedTargetModifierInfo {
+///         match self {
+///             Self::CodegenOptions(v) => v.reparse(user_value),
+///             Self::UnstableOptions(v) => v.reparse(user_value),
+///         }
+///     }
+///     pub fn is_target_modifier(flag_name: &str) -> bool {
+///         CodegenOptionsTargetModifiers::is_target_modifier(flag_name) ||
+///         UnstableOptionsTargetModifiers::is_target_modifier(flag_name)
+///     }
+/// }
+/// ```
+macro_rules! top_level_tmod_enum {
+    ($( {$($optinfo:tt)*} ),* $(,)*) => {
+        top_level_tmod_enum! { @parse {}, (user_value){}; $($($optinfo)*|)* }
+    };
+    // Termination
+    (
+        @parse
+        {$($variant:tt($substruct_enum:tt))*},
+        ($user_value:ident){$($pout:tt)*};
+    ) => {
+        #[allow(non_camel_case_types)]
+        #[derive(PartialEq, Eq, PartialOrd, Ord, Debug, Copy, Clone, Encodable, Decodable)]
+        pub enum OptionsTargetModifiers {
+            $($variant($substruct_enum)),*
+        }
+        impl OptionsTargetModifiers {
+            #[allow(unused_variables)]
+            pub fn reparse(&self, $user_value: &str) -> ExtendedTargetModifierInfo {
+                #[allow(unreachable_patterns)]
+                match self {
+                    $($pout)*
+                    _ => panic!("unknown target modifier option: {:?}", *self)
+                }
+            }
+            pub fn is_target_modifier(flag_name: &str) -> bool {
+                $($substruct_enum::is_target_modifier(flag_name))||*
+            }
+        }
+    };
+    // Adding SUBSTRUCT option group into $eout
+    (
+        @parse {$($eout:tt)*}, ($puser_value:ident){$($pout:tt)*};
+            [SUBSTRUCT $substruct_enum:ident $variant:ident] |
+        $($tail:tt)*
+    ) => {
+        top_level_tmod_enum! {
+            @parse
+            {
+                $($eout)*
+                $variant($substruct_enum)
+            },
+            ($puser_value){
+                $($pout)*
+                Self::$variant(v) => v.reparse($puser_value),
+            };
+            $($tail)*
+        }
+    };
+    // Skipping non-target-modifier and non-substruct
+    (
+        @parse {$($eout:tt)*}, ($puser_value:ident){$($pout:tt)*};
+            [$non_substruct:ident] |
+        $($tail:tt)*
+    ) => {
+        top_level_tmod_enum! {
+            @parse
+            {
+                $($eout)*
+            },
+            ($puser_value){
+                $($pout)*
+            };
+            $($tail)*
+        }
+    };
+}
+
 macro_rules! top_level_options {
     ( $( #[$top_level_attr:meta] )* pub struct Options { $(
         $( #[$attr:meta] )*
-        $opt:ident : $t:ty [$dep_tracking_marker:ident],
+        $opt:ident : $t:ty [$dep_tracking_marker:ident $( $tmod:ident $variant:ident )?],
     )* } ) => (
+        top_level_tmod_enum!( {$([$dep_tracking_marker $($tmod $variant),*])|*} );
+
         #[derive(Clone)]
         $( #[$top_level_attr] )*
         pub struct Options {
             $(
                 $( #[$attr] )*
                 pub $opt: $t
-            ),*
+            ),*,
+            pub target_modifiers: BTreeMap<OptionsTargetModifiers, String>,
         }
 
         impl Options {
@@ -98,6 +275,17 @@ macro_rules! top_level_options {
                 })*
                 hasher.finish()
             }
+
+            pub fn gather_target_modifiers(&self) -> Vec<TargetModifier> {
+                let mut mods = Vec::<TargetModifier>::new();
+                $({
+                    gather_tmods_top_level!($opt,
+                        &self.$opt, &mut mods, &self.target_modifiers,
+                        [$dep_tracking_marker $($tmod),*]);
+                })*
+                mods.sort_by(|a, b| a.opt.cmp(&b.opt));
+                mods
+            }
         }
     );
 }
@@ -165,9 +353,9 @@ top_level_options!(
         #[rustc_lint_opt_deny_field_access("should only be used via `Config::hash_untracked_state`")]
         untracked_state_hash: Hash64 [TRACKED_NO_CRATE_HASH],
 
-        unstable_opts: UnstableOptions [SUBSTRUCT],
+        unstable_opts: UnstableOptions [SUBSTRUCT UnstableOptionsTargetModifiers UnstableOptions],
         prints: Vec<PrintRequest> [UNTRACKED],
-        cg: CodegenOptions [SUBSTRUCT],
+        cg: CodegenOptions [SUBSTRUCT CodegenOptionsTargetModifiers CodegenOptions],
         externs: Externs [UNTRACKED],
         crate_name: Option<String> [TRACKED],
         /// Indicates how the compiler should treat unstable features.
@@ -226,6 +414,98 @@ top_level_options!(
     }
 );
 
+macro_rules! tmod_enum_opt {
+    ($struct_name:ident, $tmod_enum_name:ident, $opt:ident, $v:ident) => {
+        Some(OptionsTargetModifiers::$struct_name($tmod_enum_name::$opt))
+    };
+    ($struct_name:ident, $tmod_enum_name:ident, $opt:ident, ) => {
+        None
+    };
+}
+
+macro_rules! tmod_enum {
+    ($tmod_enum_name:ident, $prefix:expr, $( {$($optinfo:tt)*} ),* $(,)*) => {
+        tmod_enum! { $tmod_enum_name, $prefix, @parse {}, (user_value){}; $($($optinfo)*|)* }
+    };
+    // Termination
+    (
+        $tmod_enum_name:ident, $prefix:expr,
+        @parse
+        {$($eout:tt)*},
+        ($user_value:ident){$($pout:tt)*};
+    ) => {
+        #[allow(non_camel_case_types)]
+        #[derive(PartialEq, Eq, PartialOrd, Ord, Debug, Copy, Clone, Encodable, Decodable)]
+        pub enum $tmod_enum_name {
+            $($eout),*
+        }
+        impl $tmod_enum_name {
+            #[allow(unused_variables)]
+            pub fn reparse(&self, $user_value: &str) -> ExtendedTargetModifierInfo {
+                #[allow(unreachable_patterns)]
+                match self {
+                    $($pout)*
+                    _ => panic!("unknown target modifier option: {:?}", *self)
+                }
+            }
+            pub fn is_target_modifier(flag_name: &str) -> bool {
+                match flag_name.replace('-', "_").as_str() {
+                    $(stringify!($eout) => true,)*
+                    _ => false,
+                }
+            }
+        }
+    };
+    // Adding target-modifier option into $eout
+    (
+        $tmod_enum_name:ident, $prefix:expr,
+        @parse {$($eout:tt)*}, ($puser_value:ident){$($pout:tt)*};
+            $opt:ident, $parse:ident, $t:ty, [TARGET_MODIFIER] |
+        $($tail:tt)*
+    ) => {
+        tmod_enum! {
+            $tmod_enum_name, $prefix,
+            @parse
+            {
+                $($eout)*
+                $opt
+            },
+            ($puser_value){
+                $($pout)*
+                Self::$opt => {
+                    let mut parsed : $t = Default::default();
+                    parse::$parse(&mut parsed, Some($puser_value));
+                    ExtendedTargetModifierInfo {
+                        prefix: $prefix.to_string(),
+                        name: stringify!($opt).to_string().replace('_', "-"),
+                        tech_value: format!("{:?}", parsed),
+                    }
+                },
+            };
+            $($tail)*
+        }
+    };
+    // Skipping non-target-modifier
+    (
+        $tmod_enum_name:ident, $prefix:expr,
+        @parse {$($eout:tt)*}, ($puser_value:ident){$($pout:tt)*};
+            $opt:ident, $parse:ident, $t:ty, [] |
+        $($tail:tt)*
+    ) => {
+        tmod_enum! {
+            $tmod_enum_name, $prefix,
+            @parse
+            {
+                $($eout)*
+            },
+            ($puser_value){
+                $($pout)*
+            };
+            $($tail)*
+        }
+    };
+}
+
 /// Defines all `CodegenOptions`/`DebuggingOptions` fields and parsers all at once. The goal of this
 /// macro is to define an interface that can be programmatically used by the option parser
 /// to initialize the struct without hardcoding field names all over the place.
@@ -235,11 +515,11 @@ top_level_options!(
 /// generated code to parse an option into its respective field in the struct. There are a few
 /// hand-written parsers for parsing specific types of values in this module.
 macro_rules! options {
-    ($struct_name:ident, $stat:ident, $optmod:ident, $prefix:expr, $outputname:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $stat:ident, $optmod:ident, $prefix:expr, $outputname:expr,
      $($( #[$attr:meta] )* $opt:ident : $t:ty = (
         $init:expr,
         $parse:ident,
-        [$dep_tracking_marker:ident],
+        [$dep_tracking_marker:ident $( $tmod:ident )?],
         $desc:expr
         $(, deprecated_do_nothing: $dnn:literal )?)
      ),* ,) =>
@@ -248,6 +528,8 @@ macro_rules! options {
     #[rustc_lint_opt_ty]
     pub struct $struct_name { $( $( #[$attr] )* pub $opt: $t),* }
 
+    tmod_enum!( $tmod_enum_name, $prefix, {$($opt, $parse, $t, [$($tmod),*])|*} );
+
     impl Default for $struct_name {
         fn default() -> $struct_name {
             $struct_name { $($opt: $init),* }
@@ -258,8 +540,9 @@ macro_rules! options {
         pub fn build(
             early_dcx: &EarlyDiagCtxt,
             matches: &getopts::Matches,
+            target_modifiers: &mut BTreeMap<OptionsTargetModifiers, String>,
         ) -> $struct_name {
-            build_options(early_dcx, matches, $stat, $prefix, $outputname)
+            build_options(early_dcx, matches, target_modifiers, $stat, $prefix, $outputname)
         }
 
         fn dep_tracking_hash(&self, for_crate_hash: bool, error_format: ErrorOutputType) -> u64 {
@@ -279,11 +562,23 @@ macro_rules! options {
                                         );
             hasher.finish()
         }
+
+        pub fn gather_target_modifiers(
+            &self,
+            _mods: &mut Vec<TargetModifier>,
+            _tmod_vals: &BTreeMap<OptionsTargetModifiers, String>,
+        ) {
+            $({
+                gather_tmods!($struct_name, $tmod_enum_name, $opt, &self.$opt, _mods, _tmod_vals,
+                    [$dep_tracking_marker], [$($tmod),*]);
+            })*
+        }
     }
 
     pub const $stat: OptionDescrs<$struct_name> =
         &[ $( OptionDesc{ name: stringify!($opt), setter: $optmod::$opt,
-            type_desc: desc::$parse, desc: $desc, is_deprecated_and_do_nothing: false $( || $dnn )? } ),* ];
+            type_desc: desc::$parse, desc: $desc, is_deprecated_and_do_nothing: false $( || $dnn )?,
+            tmod: tmod_enum_opt!($struct_name, $tmod_enum_name, $opt, $($tmod),*) } ),* ];
 
     mod $optmod {
     $(
@@ -328,6 +623,7 @@ pub struct OptionDesc<O> {
     // description for option from options table
     desc: &'static str,
     is_deprecated_and_do_nothing: bool,
+    tmod: Option<OptionsTargetModifiers>,
 }
 
 impl<O> OptionDesc<O> {
@@ -344,6 +640,7 @@ impl<O> OptionDesc<O> {
 fn build_options<O: Default>(
     early_dcx: &EarlyDiagCtxt,
     matches: &getopts::Matches,
+    target_modifiers: &mut BTreeMap<OptionsTargetModifiers, String>,
     descrs: OptionDescrs<O>,
     prefix: &str,
     outputname: &str,
@@ -357,7 +654,14 @@ fn build_options<O: Default>(
 
         let option_to_lookup = key.replace('-', "_");
         match descrs.iter().find(|opt_desc| opt_desc.name == option_to_lookup) {
-            Some(OptionDesc { name: _, setter, type_desc, desc, is_deprecated_and_do_nothing }) => {
+            Some(OptionDesc {
+                name: _,
+                setter,
+                type_desc,
+                desc,
+                is_deprecated_and_do_nothing,
+                tmod,
+            }) => {
                 if *is_deprecated_and_do_nothing {
                     // deprecation works for prefixed options only
                     assert!(!prefix.is_empty());
@@ -377,6 +681,11 @@ fn build_options<O: Default>(
                         ),
                     }
                 }
+                if let Some(tmod) = *tmod
+                    && let Some(value) = value
+                {
+                    target_modifiers.insert(tmod, value.to_string());
+                }
             }
             None => early_dcx.early_fatal(format!("unknown {outputname} option: `{key}`")),
         }
@@ -1614,7 +1923,7 @@ pub mod parse {
 }
 
 options! {
-    CodegenOptions, CG_OPTIONS, cgopts, "C", "codegen",
+    CodegenOptions, CodegenOptionsTargetModifiers, CG_OPTIONS, cgopts, "C", "codegen",
 
     // If you add a new option, please update:
     // - compiler/rustc_interface/src/tests.rs
@@ -1745,6 +2054,8 @@ options! {
     target_feature: String = (String::new(), parse_target_feature, [TRACKED],
         "target specific attributes. (`rustc --print target-features` for details). \
         This feature is unsafe."),
+    unsafe_allow_abi_mismatch: Vec<String> = (Vec::new(), parse_comma_list, [UNTRACKED],
+        "Allow incompatible target modifiers in dependency crates (comma separated list)"),
     // tidy-alphabetical-end
 
     // If you add a new option, please update:
@@ -1753,7 +2064,7 @@ options! {
 }
 
 options! {
-    UnstableOptions, Z_OPTIONS, dbopts, "Z", "unstable",
+    UnstableOptions, UnstableOptionsTargetModifiers, Z_OPTIONS, dbopts, "Z", "unstable",
 
     // If you add a new option, please update:
     // - compiler/rustc_interface/src/tests.rs
@@ -2098,10 +2409,10 @@ options! {
         "enable queries of the dependency graph for regression testing (default: no)"),
     randomize_layout: bool = (false, parse_bool, [TRACKED],
         "randomize the layout of types (default: no)"),
-    reg_struct_return: bool = (false, parse_bool, [TRACKED],
+    reg_struct_return: bool = (false, parse_bool, [TRACKED TARGET_MODIFIER],
         "On x86-32 targets, it overrides the default ABI to return small structs in registers.
         It is UNSOUND to link together crates that use different values for this flag!"),
-    regparm: Option<u32> = (None, parse_opt_number, [TRACKED],
+    regparm: Option<u32> = (None, parse_opt_number, [TRACKED TARGET_MODIFIER],
         "On x86-32 targets, setting this to N causes the compiler to pass N arguments \
         in registers EAX, EDX, and ECX instead of on the stack for\
         \"C\", \"cdecl\", and \"stdcall\" fn.\
diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index 7b040a8b2c4..0ac6f17b97b 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -649,7 +649,8 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
                 // HACK(jaic1): hide the `str` type behind a reference
                 // for the following transformation from valtree to raw bytes
                 let ref_ty = Ty::new_imm_ref(tcx, tcx.lifetimes.re_static, ct_ty);
-                let slice = valtree.try_to_raw_bytes(tcx, ref_ty).unwrap_or_else(|| {
+                let cv = ty::Value { ty: ref_ty, valtree };
+                let slice = cv.try_to_raw_bytes(tcx).unwrap_or_else(|| {
                     bug!("expected to get raw bytes from valtree {:?} for type {:}", valtree, ct_ty)
                 });
                 let s = std::str::from_utf8(slice).expect("non utf8 str from MIR interpreter");
diff --git a/compiler/rustc_target/src/spec/json.rs b/compiler/rustc_target/src/spec/json.rs
index 015ea97f2ac..a6b0ec072e8 100644
--- a/compiler/rustc_target/src/spec/json.rs
+++ b/compiler/rustc_target/src/spec/json.rs
@@ -128,6 +128,19 @@ impl Target {
                     Some(Ok(()))
                 })).unwrap_or(Ok(()))
             } );
+            ($key_name:ident, RustcAbi) => ( {
+                let name = (stringify!($key_name)).replace("_", "-");
+                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
+                    match s.parse::<super::RustcAbi>() {
+                        Ok(rustc_abi) => base.$key_name = Some(rustc_abi),
+                        _ => return Some(Err(format!(
+                            "'{s}' is not a valid value for rustc-abi. \
+                            Use 'x86-softfloat' or leave the field unset."
+                        ))),
+                    }
+                    Some(Ok(()))
+                })).unwrap_or(Ok(()))
+            } );
             ($key_name:ident, RelocModel) => ( {
                 let name = (stringify!($key_name)).replace("_", "-");
                 obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
@@ -612,6 +625,7 @@ impl Target {
         key!(llvm_mcount_intrinsic, optional);
         key!(llvm_abiname);
         key!(llvm_floatabi, FloatAbi)?;
+        key!(rustc_abi, RustcAbi)?;
         key!(relax_elf_relocations, bool);
         key!(llvm_args, list);
         key!(use_ctors_section, bool);
@@ -788,6 +802,7 @@ impl ToJson for Target {
         target_option_val!(llvm_mcount_intrinsic);
         target_option_val!(llvm_abiname);
         target_option_val!(llvm_floatabi);
+        target_option_val!(rustc_abi);
         target_option_val!(relax_elf_relocations);
         target_option_val!(llvm_args);
         target_option_val!(use_ctors_section);
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 3fc7a07fb91..72600225e7a 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -1114,6 +1114,33 @@ impl ToJson for FloatAbi {
     }
 }
 
+/// The Rustc-specific variant of the ABI used for this target.
+#[derive(Clone, Copy, PartialEq, Hash, Debug)]
+pub enum RustcAbi {
+    /// On x86-32/64 only: do not use any FPU or SIMD registers for the ABI.
+    X86Softfloat,
+}
+
+impl FromStr for RustcAbi {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<RustcAbi, ()> {
+        Ok(match s {
+            "x86-softfloat" => RustcAbi::X86Softfloat,
+            _ => return Err(()),
+        })
+    }
+}
+
+impl ToJson for RustcAbi {
+    fn to_json(&self) -> Json {
+        match *self {
+            RustcAbi::X86Softfloat => "x86-softfloat",
+        }
+        .to_json()
+    }
+}
+
 #[derive(Clone, Copy, PartialEq, Hash, Debug)]
 pub enum TlsModel {
     GeneralDynamic,
@@ -2505,6 +2532,12 @@ pub struct TargetOptions {
     /// If not provided, LLVM will infer the float ABI from the target triple (`llvm_target`).
     pub llvm_floatabi: Option<FloatAbi>,
 
+    /// Picks a specific ABI for this target. This is *not* just for "Rust" ABI functions,
+    /// it can also affect "C" ABI functions; the point is that this flag is interpreted by
+    /// rustc and not forwarded to LLVM.
+    /// So far, this is only used on x86.
+    pub rustc_abi: Option<RustcAbi>,
+
     /// Whether or not RelaxElfRelocation flag will be passed to the linker
     pub relax_elf_relocations: bool,
 
@@ -2664,10 +2697,6 @@ impl TargetOptions {
                 .collect();
         }
     }
-
-    pub(crate) fn has_feature(&self, search_feature: &str) -> bool {
-        self.features.split(',').any(|f| f.strip_prefix('+').is_some_and(|f| f == search_feature))
-    }
 }
 
 impl Default for TargetOptions {
@@ -2774,6 +2803,7 @@ impl Default for TargetOptions {
             llvm_mcount_intrinsic: None,
             llvm_abiname: "".into(),
             llvm_floatabi: None,
+            rustc_abi: None,
             relax_elf_relocations: false,
             llvm_args: cvs![],
             use_ctors_section: false,
@@ -3240,6 +3270,17 @@ impl Target {
             _ => {}
         }
 
+        // Check consistency of Rust ABI declaration.
+        if let Some(rust_abi) = self.rustc_abi {
+            match rust_abi {
+                RustcAbi::X86Softfloat => check_matches!(
+                    &*self.arch,
+                    "x86" | "x86_64",
+                    "`x86-softfloat` ABI is only valid for x86 targets"
+                ),
+            }
+        }
+
         // Check that the given target-features string makes some basic sense.
         if !self.features.is_empty() {
             let mut features_enabled = FxHashSet::default();
diff --git a/compiler/rustc_target/src/spec/targets/i686_unknown_uefi.rs b/compiler/rustc_target/src/spec/targets/i686_unknown_uefi.rs
index 39d3a5a4633..c1ed565f0fe 100644
--- a/compiler/rustc_target/src/spec/targets/i686_unknown_uefi.rs
+++ b/compiler/rustc_target/src/spec/targets/i686_unknown_uefi.rs
@@ -5,7 +5,7 @@
 // The cdecl ABI is used. It differs from the stdcall or fastcall ABI.
 // "i686-unknown-windows" is used to get the minimal subset of windows-specific features.
 
-use crate::spec::{Target, base};
+use crate::spec::{RustcAbi, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::uefi_msvc::opts();
@@ -22,6 +22,7 @@ pub(crate) fn target() -> Target {
     // If you initialize FP units yourself, you can override these flags with custom linker
     // arguments, thus giving you access to full MMX/SSE acceleration.
     base.features = "-mmx,-sse,+soft-float".into();
+    base.rustc_abi = Some(RustcAbi::X86Softfloat);
 
     // Use -GNU here, because of the reason below:
     // Background and Problem:
diff --git a/compiler/rustc_target/src/spec/targets/x86_64_unknown_none.rs b/compiler/rustc_target/src/spec/targets/x86_64_unknown_none.rs
index cfefb1de993..e14a3673589 100644
--- a/compiler/rustc_target/src/spec/targets/x86_64_unknown_none.rs
+++ b/compiler/rustc_target/src/spec/targets/x86_64_unknown_none.rs
@@ -5,8 +5,8 @@
 // features.
 
 use crate::spec::{
-    Cc, CodeModel, LinkerFlavor, Lld, PanicStrategy, RelroLevel, SanitizerSet, StackProbeType,
-    Target, TargetOptions,
+    Cc, CodeModel, LinkerFlavor, Lld, PanicStrategy, RelroLevel, RustcAbi, SanitizerSet,
+    StackProbeType, Target, TargetOptions,
 };
 
 pub(crate) fn target() -> Target {
@@ -20,6 +20,7 @@ pub(crate) fn target() -> Target {
         relro_level: RelroLevel::Full,
         linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
         linker: Some("rust-lld".into()),
+        rustc_abi: Some(RustcAbi::X86Softfloat),
         features: "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2,+soft-float".into(),
         supported_sanitizers: SanitizerSet::KCFI | SanitizerSet::KERNELADDRESS,
         disable_redzone: true,
diff --git a/compiler/rustc_target/src/spec/targets/x86_64_unknown_uefi.rs b/compiler/rustc_target/src/spec/targets/x86_64_unknown_uefi.rs
index a11a79ff41a..8fd92e8123b 100644
--- a/compiler/rustc_target/src/spec/targets/x86_64_unknown_uefi.rs
+++ b/compiler/rustc_target/src/spec/targets/x86_64_unknown_uefi.rs
@@ -6,7 +6,7 @@
 // LLVM. "x86_64-unknown-windows" is used to get the minimal subset of windows-specific features.
 
 use crate::abi::call::Conv;
-use crate::spec::{Target, base};
+use crate::spec::{RustcAbi, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::uefi_msvc::opts();
@@ -26,6 +26,7 @@ pub(crate) fn target() -> Target {
     // If you initialize FP units yourself, you can override these flags with custom linker
     // arguments, thus giving you access to full MMX/SSE acceleration.
     base.features = "-mmx,-sse,+soft-float".into();
+    base.rustc_abi = Some(RustcAbi::X86Softfloat);
 
     Target {
         llvm_target: "x86_64-unknown-windows".into(),
diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index 0d8a4988dce..5355a4ad532 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -5,7 +5,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_span::{Symbol, sym};
 
-use crate::spec::{FloatAbi, Target};
+use crate::spec::{FloatAbi, RustcAbi, Target};
 
 /// Features that control behaviour of rustc, rather than the codegen.
 /// These exist globally and are not in the target-specific lists below.
@@ -422,7 +422,9 @@ const X86_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("sha512", Unstable(sym::sha512_sm_x86), &["avx2"]),
     ("sm3", Unstable(sym::sha512_sm_x86), &["avx"]),
     ("sm4", Unstable(sym::sha512_sm_x86), &["avx2"]),
-    ("soft-float", Stability::Forbidden { reason: "unsound because it changes float ABI" }, &[]),
+    // This cannot actually be toggled, the ABI always fixes it, so it'd make little sense to
+    // stabilize. It must be in this list for the ABI check to be able to use it.
+    ("soft-float", Stability::Unstable(sym::x87_target_feature), &[]),
     ("sse", Stable, &[]),
     ("sse2", Stable, &["sse"]),
     ("sse3", Stable, &["sse2"]),
@@ -773,23 +775,41 @@ impl Target {
         // questions "which ABI is used".
         match &*self.arch {
             "x86" => {
-                // We support 2 ABIs, hardfloat (default) and softfloat.
-                // x86 has no sane ABI indicator so we have to use the target feature.
-                if self.has_feature("soft-float") {
-                    NOTHING
-                } else {
-                    // Hardfloat ABI. x87 must be enabled.
-                    FeatureConstraints { required: &["x87"], incompatible: &[] }
+                // We use our own ABI indicator here; LLVM does not have anything native.
+                // Every case should require or forbid `soft-float`!
+                match self.rustc_abi {
+                    None => {
+                        // Default hardfloat ABI.
+                        // x87 must be enabled, soft-float must be disabled.
+                        FeatureConstraints { required: &["x87"], incompatible: &["soft-float"] }
+                    }
+                    Some(RustcAbi::X86Softfloat) => {
+                        // Softfloat ABI, requires corresponding target feature. That feature trumps
+                        // `x87` and all other FPU features so those do not matter.
+                        // Note that this one requirement is the entire implementation of the ABI!
+                        // LLVM handles the rest.
+                        FeatureConstraints { required: &["soft-float"], incompatible: &[] }
+                    }
                 }
             }
             "x86_64" => {
-                // We support 2 ABIs, hardfloat (default) and softfloat.
-                // x86 has no sane ABI indicator so we have to use the target feature.
-                if self.has_feature("soft-float") {
-                    NOTHING
-                } else {
-                    // Hardfloat ABI. x87 and SSE2 must be enabled.
-                    FeatureConstraints { required: &["x87", "sse2"], incompatible: &[] }
+                // We use our own ABI indicator here; LLVM does not have anything native.
+                // Every case should require or forbid `soft-float`!
+                match self.rustc_abi {
+                    None => {
+                        // Default hardfloat ABI. On x86-64, this always includes SSE2.
+                        FeatureConstraints {
+                            required: &["x87", "sse2"],
+                            incompatible: &["soft-float"],
+                        }
+                    }
+                    Some(RustcAbi::X86Softfloat) => {
+                        // Softfloat ABI, requires corresponding target feature. That feature trumps
+                        // `x87` and all other FPU features so those do not matter.
+                        // Note that this one requirement is the entire implementation of the ABI!
+                        // LLVM handles the rest.
+                        FeatureConstraints { required: &["soft-float"], incompatible: &[] }
+                    }
                 }
             }
             "arm" => {
diff --git a/compiler/rustc_type_ir/src/fold.rs b/compiler/rustc_type_ir/src/fold.rs
index d337a1a8ad9..711e42ff055 100644
--- a/compiler/rustc_type_ir/src/fold.rs
+++ b/compiler/rustc_type_ir/src/fold.rs
@@ -73,7 +73,7 @@ type Never = std::convert::Infallible;
 /// which means in practice almost every foldable type needs to also be
 /// visitable. (However, there are some types that are visitable without being
 /// foldable.)
-pub trait TypeFoldable<I: Interner>: TypeVisitable<I> {
+pub trait TypeFoldable<I: Interner>: TypeVisitable<I> + Clone {
     /// The entry point for folding. To fold a value `t` with a folder `f`
     /// call: `t.try_fold_with(f)`.
     ///
diff --git a/compiler/rustc_type_ir/src/visit.rs b/compiler/rustc_type_ir/src/visit.rs
index 3213638afb2..0a074942170 100644
--- a/compiler/rustc_type_ir/src/visit.rs
+++ b/compiler/rustc_type_ir/src/visit.rs
@@ -59,7 +59,7 @@ use crate::{self as ty, Interner, TypeFlags};
 ///
 /// To implement this conveniently, use the derive macro located in
 /// `rustc_macros`.
-pub trait TypeVisitable<I: Interner>: fmt::Debug + Clone {
+pub trait TypeVisitable<I: Interner>: fmt::Debug {
     /// The entry point for visiting. To visit a value `t` with a visitor `v`
     /// call: `t.visit_with(v)`.
     ///
diff --git a/library/core/src/cell/once.rs b/library/core/src/cell/once.rs
index 6a85791916a..c6c96571d33 100644
--- a/library/core/src/cell/once.rs
+++ b/library/core/src/cell/once.rs
@@ -8,6 +8,9 @@ use crate::{fmt, mem};
 /// only immutable references can be obtained unless one has a mutable reference to the cell
 /// itself. In the same vein, the cell can only be re-initialized with such a mutable reference.
 ///
+/// A `OnceCell` can be thought of as a safe abstraction over uninitialized data that becomes
+/// initialized once written.
+///
 /// For a thread-safe version of this struct, see [`std::sync::OnceLock`].
 ///
 /// [`RefCell`]: crate::cell::RefCell
@@ -35,7 +38,7 @@ pub struct OnceCell<T> {
 }
 
 impl<T> OnceCell<T> {
-    /// Creates a new empty cell.
+    /// Creates a new uninitialized cell.
     #[inline]
     #[must_use]
     #[stable(feature = "once_cell", since = "1.70.0")]
@@ -46,7 +49,7 @@ impl<T> OnceCell<T> {
 
     /// Gets the reference to the underlying value.
     ///
-    /// Returns `None` if the cell is empty.
+    /// Returns `None` if the cell is uninitialized.
     #[inline]
     #[stable(feature = "once_cell", since = "1.70.0")]
     pub fn get(&self) -> Option<&T> {
@@ -56,19 +59,19 @@ impl<T> OnceCell<T> {
 
     /// Gets the mutable reference to the underlying value.
     ///
-    /// Returns `None` if the cell is empty.
+    /// Returns `None` if the cell is uninitialized.
     #[inline]
     #[stable(feature = "once_cell", since = "1.70.0")]
     pub fn get_mut(&mut self) -> Option<&mut T> {
         self.inner.get_mut().as_mut()
     }
 
-    /// Sets the contents of the cell to `value`.
+    /// Initializes the contents of the cell to `value`.
     ///
     /// # Errors
     ///
-    /// This method returns `Ok(())` if the cell was empty and `Err(value)` if
-    /// it was full.
+    /// This method returns `Ok(())` if the cell was uninitialized
+    /// and `Err(value)` if it was already initialized.
     ///
     /// # Examples
     ///
@@ -92,13 +95,13 @@ impl<T> OnceCell<T> {
         }
     }
 
-    /// Sets the contents of the cell to `value` if the cell was empty, then
-    /// returns a reference to it.
+    /// Initializes the contents of the cell to `value` if the cell was
+    /// uninitialized, then returns a reference to it.
     ///
     /// # Errors
     ///
-    /// This method returns `Ok(&value)` if the cell was empty and
-    /// `Err(&current_value, value)` if it was full.
+    /// This method returns `Ok(&value)` if the cell was uninitialized
+    /// and `Err((&current_value, value))` if it was already initialized.
     ///
     /// # Examples
     ///
@@ -130,12 +133,12 @@ impl<T> OnceCell<T> {
         Ok(slot.insert(value))
     }
 
-    /// Gets the contents of the cell, initializing it with `f`
-    /// if the cell was empty.
+    /// Gets the contents of the cell, initializing it to `f()`
+    /// if the cell was uninitialized.
     ///
     /// # Panics
     ///
-    /// If `f` panics, the panic is propagated to the caller, and the cell
+    /// If `f()` panics, the panic is propagated to the caller, and the cell
     /// remains uninitialized.
     ///
     /// It is an error to reentrantly initialize the cell from `f`. Doing
@@ -164,11 +167,11 @@ impl<T> OnceCell<T> {
     }
 
     /// Gets the mutable reference of the contents of the cell,
-    /// initializing it with `f` if the cell was empty.
+    /// initializing it to `f()` if the cell was uninitialized.
     ///
     /// # Panics
     ///
-    /// If `f` panics, the panic is propagated to the caller, and the cell
+    /// If `f()` panics, the panic is propagated to the caller, and the cell
     /// remains uninitialized.
     ///
     /// # Examples
@@ -199,13 +202,13 @@ impl<T> OnceCell<T> {
         }
     }
 
-    /// Gets the contents of the cell, initializing it with `f` if
-    /// the cell was empty. If the cell was empty and `f` failed, an
-    /// error is returned.
+    /// Gets the contents of the cell, initializing it to `f()` if
+    /// the cell was uninitialized. If the cell was uninitialized
+    /// and `f()` failed, an error is returned.
     ///
     /// # Panics
     ///
-    /// If `f` panics, the panic is propagated to the caller, and the cell
+    /// If `f()` panics, the panic is propagated to the caller, and the cell
     /// remains uninitialized.
     ///
     /// It is an error to reentrantly initialize the cell from `f`. Doing
@@ -239,12 +242,12 @@ impl<T> OnceCell<T> {
     }
 
     /// Gets the mutable reference of the contents of the cell, initializing
-    /// it with `f` if the cell was empty. If the cell was empty and `f` failed,
-    /// an error is returned.
+    /// it to `f()` if the cell was uninitialized. If the cell was uninitialized
+    /// and `f()` failed, an error is returned.
     ///
     /// # Panics
     ///
-    /// If `f` panics, the panic is propagated to the caller, and the cell
+    /// If `f()` panics, the panic is propagated to the caller, and the cell
     /// remains uninitialized.
     ///
     /// # Examples
@@ -256,7 +259,7 @@ impl<T> OnceCell<T> {
     ///
     /// let mut cell: OnceCell<u32> = OnceCell::new();
     ///
-    /// // Failed initializers do not change the value
+    /// // Failed attempts to initialize the cell do not change its contents
     /// assert!(cell.get_mut_or_try_init(|| "not a number!".parse()).is_err());
     /// assert!(cell.get().is_none());
     ///
@@ -295,7 +298,7 @@ impl<T> OnceCell<T> {
 
     /// Consumes the cell, returning the wrapped value.
     ///
-    /// Returns `None` if the cell was empty.
+    /// Returns `None` if the cell was uninitialized.
     ///
     /// # Examples
     ///
@@ -321,7 +324,7 @@ impl<T> OnceCell<T> {
 
     /// Takes the value out of this `OnceCell`, moving it back to an uninitialized state.
     ///
-    /// Has no effect and returns `None` if the `OnceCell` hasn't been initialized.
+    /// Has no effect and returns `None` if the `OnceCell` is uninitialized.
     ///
     /// Safety is guaranteed by requiring a mutable reference.
     ///
diff --git a/library/core/src/primitive_docs.rs b/library/core/src/primitive_docs.rs
index c5f029363e5..bbf5939fe1b 100644
--- a/library/core/src/primitive_docs.rs
+++ b/library/core/src/primitive_docs.rs
@@ -1160,9 +1160,9 @@ impl<T> (T,) {}
 ///
 /// Note that most common platforms will not support `f16` in hardware without enabling extra target
 /// features, with the notable exception of Apple Silicon (also known as M1, M2, etc.) processors.
-/// Hardware support on x86-64 requires the avx512fp16 feature, while RISC-V requires Zhf.
-/// Usually the fallback implementation will be to use `f32` hardware if it exists, and convert
-/// between `f16` and `f32` when performing math.
+/// Hardware support on x86/x86-64 requires the avx512fp16 or avx10.1 features, while RISC-V requires
+/// Zfh, and Arm/AArch64 requires FEAT_FP16.  Usually the fallback implementation will be to use `f32`
+/// hardware if it exists, and convert between `f16` and `f32` when performing math.
 ///
 /// *[See also the `std::f16::consts` module](crate::f16::consts).*
 ///
@@ -1344,10 +1344,10 @@ mod prim_f64 {}
 /// quad-precision values][wikipedia] for more information.
 ///
 /// Note that no platforms have hardware support for `f128` without enabling target specific features,
-/// as for all instruction set architectures `f128` is considered an optional feature.
-/// Only Power ISA ("PowerPC") and RISC-V specify it, and only certain microarchitectures
-/// actually implement it. For x86-64 and AArch64, ISA support is not even specified,
-/// so it will always be a software implementation significantly slower than `f64`.
+/// as for all instruction set architectures `f128` is considered an optional feature.  Only Power ISA
+/// ("PowerPC") and RISC-V (via the Q extension) specify it, and only certain microarchitectures
+/// actually implement it. For x86-64 and AArch64, ISA support is not even specified, so it will always
+/// be a software implementation significantly slower than `f64`.
 ///
 /// _Note: `f128` support is incomplete. Many platforms will not be able to link math functions. On
 /// x86 in particular, these functions do link but their results are always incorrect._
diff --git a/library/std/src/sync/once_lock.rs b/library/std/src/sync/once_lock.rs
index 6fc0abbed9e..8f769f2dca3 100644
--- a/library/std/src/sync/once_lock.rs
+++ b/library/std/src/sync/once_lock.rs
@@ -13,6 +13,9 @@ use crate::sync::Once;
 /// Where OnceLock shines is when LazyLock is too simple to support a given case, as LazyLock
 /// doesn't allow additional inputs to its function after you call [`LazyLock::new(|| ...)`].
 ///
+/// A `OnceLock` can be thought of as a safe abstraction over uninitialized data that becomes
+/// initialized once written.
+///
 /// [`OnceCell`]: crate::cell::OnceCell
 /// [`LazyLock<T, F>`]: crate::sync::LazyLock
 /// [`LazyLock::new(|| ...)`]: crate::sync::LazyLock::new
@@ -126,7 +129,7 @@ pub struct OnceLock<T> {
 }
 
 impl<T> OnceLock<T> {
-    /// Creates a new empty cell.
+    /// Creates a new uninitialized cell.
     #[inline]
     #[must_use]
     #[stable(feature = "once_cell", since = "1.70.0")]
@@ -141,8 +144,8 @@ impl<T> OnceLock<T> {
 
     /// Gets the reference to the underlying value.
     ///
-    /// Returns `None` if the cell is empty, or being initialized. This
-    /// method never blocks.
+    /// Returns `None` if the cell is uninitialized, or being initialized.
+    /// This method never blocks.
     #[inline]
     #[stable(feature = "once_cell", since = "1.70.0")]
     pub fn get(&self) -> Option<&T> {
@@ -156,7 +159,8 @@ impl<T> OnceLock<T> {
 
     /// Gets the mutable reference to the underlying value.
     ///
-    /// Returns `None` if the cell is empty. This method never blocks.
+    /// Returns `None` if the cell is uninitialized, or being initialized.
+    /// This method never blocks.
     #[inline]
     #[stable(feature = "once_cell", since = "1.70.0")]
     pub fn get_mut(&mut self) -> Option<&mut T> {
@@ -194,12 +198,13 @@ impl<T> OnceLock<T> {
         unsafe { self.get_unchecked() }
     }
 
-    /// Sets the contents of this cell to `value`.
+    /// Initializes the contents of the cell to `value`.
     ///
     /// May block if another thread is currently attempting to initialize the cell. The cell is
-    /// guaranteed to contain a value when set returns, though not necessarily the one provided.
+    /// guaranteed to contain a value when `set` returns, though not necessarily the one provided.
     ///
-    /// Returns `Ok(())` if the cell's value was set by this call.
+    /// Returns `Ok(())` if the cell was uninitialized and
+    /// `Err(value)` if the cell was already initialized.
     ///
     /// # Examples
     ///
@@ -228,13 +233,15 @@ impl<T> OnceLock<T> {
         }
     }
 
-    /// Sets the contents of this cell to `value` if the cell was empty, then
-    /// returns a reference to it.
+    /// Initializes the contents of the cell to `value` if the cell was uninitialized,
+    /// then returns a reference to it.
     ///
     /// May block if another thread is currently attempting to initialize the cell. The cell is
-    /// guaranteed to contain a value when set returns, though not necessarily the one provided.
+    /// guaranteed to contain a value when `try_insert` returns, though not necessarily the
+    /// one provided.
     ///
-    /// Returns `Ok(&value)` if the cell was empty and `Err(&current_value, value)` if it was full.
+    /// Returns `Ok(&value)` if the cell was uninitialized and
+    /// `Err((&current_value, value))` if it was already initialized.
     ///
     /// # Examples
     ///
@@ -267,8 +274,8 @@ impl<T> OnceLock<T> {
         }
     }
 
-    /// Gets the contents of the cell, initializing it with `f` if the cell
-    /// was empty.
+    /// Gets the contents of the cell, initializing it to `f()` if the cell
+    /// was uninitialized.
     ///
     /// Many threads may call `get_or_init` concurrently with different
     /// initializing functions, but it is guaranteed that only one function
@@ -276,7 +283,7 @@ impl<T> OnceLock<T> {
     ///
     /// # Panics
     ///
-    /// If `f` panics, the panic is propagated to the caller, and the cell
+    /// If `f()` panics, the panic is propagated to the caller, and the cell
     /// remains uninitialized.
     ///
     /// It is an error to reentrantly initialize the cell from `f`. The
@@ -306,13 +313,13 @@ impl<T> OnceLock<T> {
     }
 
     /// Gets the mutable reference of the contents of the cell, initializing
-    /// it with `f` if the cell was empty.
+    /// it to `f()` if the cell was uninitialized.
     ///
     /// This method never blocks.
     ///
     /// # Panics
     ///
-    /// If `f` panics, the panic is propagated to the caller, and the cell
+    /// If `f()` panics, the panic is propagated to the caller, and the cell
     /// remains uninitialized.
     ///
     /// # Examples
@@ -343,13 +350,13 @@ impl<T> OnceLock<T> {
         }
     }
 
-    /// Gets the contents of the cell, initializing it with `f` if
-    /// the cell was empty. If the cell was empty and `f` failed, an
-    /// error is returned.
+    /// Gets the contents of the cell, initializing it to `f()` if
+    /// the cell was uninitialized. If the cell was uninitialized
+    /// and `f()` failed, an error is returned.
     ///
     /// # Panics
     ///
-    /// If `f` panics, the panic is propagated to the caller, and
+    /// If `f()` panics, the panic is propagated to the caller, and
     /// the cell remains uninitialized.
     ///
     /// It is an error to reentrantly initialize the cell from `f`.
@@ -395,14 +402,14 @@ impl<T> OnceLock<T> {
     }
 
     /// Gets the mutable reference of the contents of the cell, initializing
-    /// it with `f` if the cell was empty. If the cell was empty and `f` failed,
-    /// an error is returned.
+    /// it to `f()` if the cell was uninitialized. If the cell was uninitialized
+    /// and `f()` failed, an error is returned.
     ///
     /// This method never blocks.
     ///
     /// # Panics
     ///
-    /// If `f` panics, the panic is propagated to the caller, and
+    /// If `f()` panics, the panic is propagated to the caller, and
     /// the cell remains uninitialized.
     ///
     /// # Examples
@@ -414,7 +421,7 @@ impl<T> OnceLock<T> {
     ///
     /// let mut cell: OnceLock<u32> = OnceLock::new();
     ///
-    /// // Failed initializers do not change the value
+    /// // Failed attempts to initialize the cell do not change its contents
     /// assert!(cell.get_mut_or_try_init(|| "not a number!".parse()).is_err());
     /// assert!(cell.get().is_none());
     ///
@@ -438,7 +445,7 @@ impl<T> OnceLock<T> {
     }
 
     /// Consumes the `OnceLock`, returning the wrapped value. Returns
-    /// `None` if the cell was empty.
+    /// `None` if the cell was uninitialized.
     ///
     /// # Examples
     ///
@@ -460,7 +467,7 @@ impl<T> OnceLock<T> {
 
     /// Takes the value out of this `OnceLock`, moving it back to an uninitialized state.
     ///
-    /// Has no effect and returns `None` if the `OnceLock` hasn't been initialized.
+    /// Has no effect and returns `None` if the `OnceLock` was uninitialized.
     ///
     /// Safety is guaranteed by requiring a mutable reference.
     ///
@@ -526,7 +533,7 @@ impl<T> OnceLock<T> {
 
     /// # Safety
     ///
-    /// The value must be initialized
+    /// The cell must be initialized
     #[inline]
     unsafe fn get_unchecked(&self) -> &T {
         debug_assert!(self.is_initialized());
@@ -535,7 +542,7 @@ impl<T> OnceLock<T> {
 
     /// # Safety
     ///
-    /// The value must be initialized
+    /// The cell must be initialized
     #[inline]
     unsafe fn get_unchecked_mut(&mut self) -> &mut T {
         debug_assert!(self.is_initialized());
@@ -560,7 +567,7 @@ impl<T: UnwindSafe> UnwindSafe for OnceLock<T> {}
 
 #[stable(feature = "once_cell", since = "1.70.0")]
 impl<T> Default for OnceLock<T> {
-    /// Creates a new empty cell.
+    /// Creates a new uninitialized cell.
     ///
     /// # Example
     ///
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index 98490118f7d..781d0e602c3 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -700,7 +700,7 @@ trait Merge {
 impl Merge for TomlConfig {
     fn merge(
         &mut self,
-        TomlConfig { build, install, llvm, rust, dist, target, profile: _, change_id }: Self,
+        TomlConfig { build, install, llvm, rust, dist, target, profile, change_id }: Self,
         replace: ReplaceOpt,
     ) {
         fn do_merge<T: Merge>(x: &mut Option<T>, y: Option<T>, replace: ReplaceOpt) {
@@ -712,7 +712,10 @@ impl Merge for TomlConfig {
                 }
             }
         }
+
         self.change_id.inner.merge(change_id.inner, replace);
+        self.profile.merge(profile, replace);
+
         do_merge(&mut self.build, build, replace);
         do_merge(&mut self.install, install, replace);
         do_merge(&mut self.llvm, llvm, replace);
@@ -1505,6 +1508,10 @@ impl Config {
             build.cargo = build.cargo.take().or(std::env::var_os("CARGO").map(|p| p.into()));
         }
 
+        if GitInfo::new(false, &config.src).is_from_tarball() && toml.profile.is_none() {
+            toml.profile = Some("dist".into());
+        }
+
         if let Some(include) = &toml.profile {
             // Allows creating alias for profile names, allowing
             // profiles to be renamed while maintaining back compatibility
diff --git a/src/ci/docker/scripts/rfl-build.sh b/src/ci/docker/scripts/rfl-build.sh
index 8776e0f0be9..3eb85ab215e 100755
--- a/src/ci/docker/scripts/rfl-build.sh
+++ b/src/ci/docker/scripts/rfl-build.sh
@@ -2,7 +2,7 @@
 
 set -euo pipefail
 
-LINUX_VERSION=v6.13-rc1
+LINUX_VERSION=50e57739141b41f731ab31f8380821c7969f9dc4
 
 # Build rustc, rustdoc, cargo, clippy-driver and rustfmt
 ../x.py build --stage 2 library rustdoc clippy rustfmt
@@ -28,7 +28,7 @@ rm -rf linux || true
 # Download Linux at a specific commit
 mkdir -p linux
 git -C linux init
-git -C linux remote add origin https://github.com/Rust-for-Linux/linux.git
+git -C linux remote add origin https://github.com/Darksonn/linux.git
 git -C linux fetch --depth 1 origin ${LINUX_VERSION}
 git -C linux checkout FETCH_HEAD
 
diff --git a/src/ci/github-actions/jobs.yml b/src/ci/github-actions/jobs.yml
index 2bbe3756580..58a9eb69666 100644
--- a/src/ci/github-actions/jobs.yml
+++ b/src/ci/github-actions/jobs.yml
@@ -558,7 +558,7 @@ auto:
       SCRIPT: python x.py build --set rust.debug=true opt-dist && PGO_HOST=x86_64-pc-windows-msvc ./build/x86_64-pc-windows-msvc/stage0-tools-bin/opt-dist windows-ci -- python x.py dist bootstrap --include-default-paths
       DIST_REQUIRE_ALL_TOOLS: 1
       CODEGEN_BACKENDS: llvm,cranelift
-    <<: *job-windows-8c
+    <<: *job-windows-25-8c
 
   - name: dist-i686-msvc
     env:
diff --git a/src/doc/book b/src/doc/book
-Subproject fa312a343fbff01bc6cef393e326817f7071981
+Subproject e2fa4316c5a7c0d2499c5d6b799adcfad6ef7a4
diff --git a/src/doc/edition-guide b/src/doc/edition-guide
-Subproject 4ed5a1a4a2a7ecc2e529a5baaef04f7bc7917ed
+Subproject f56aecc3b036dff16404b525a83b00f911b9bbe
diff --git a/src/doc/nomicon b/src/doc/nomicon
-Subproject bc2298865544695c63454fc1f9f98a3dc22e994
+Subproject 336f75835a6c0514852cc65aba9a698b699b13c
diff --git a/src/doc/reference b/src/doc/reference
-Subproject 93b921c7d3213d38d920f7f905a3bec093d2217
+Subproject 4249fb411dd27f945e2881eb0378044b94cee06
diff --git a/src/doc/rust-by-example b/src/doc/rust-by-example
-Subproject 054259ed1bf01cdee4309ee764c7e103f6df3de
+Subproject 743766929f1e53e72fab74394ae259bbfb4a761
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index 8227dfa043e..3b6abdd8483 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -34,9 +34,9 @@ target | notes
 -------|-------
 [`aarch64-apple-darwin`](platform-support/apple-darwin.md) | ARM64 macOS (11.0+, Big Sur+)
 `aarch64-unknown-linux-gnu` | ARM64 Linux (kernel 4.1, glibc 2.17+)
-`i686-pc-windows-gnu` | 32-bit MinGW (Windows 10+, Windows Server 2016+) [^x86_32-floats-return-ABI]
-`i686-pc-windows-msvc` | 32-bit MSVC (Windows 10+, Windows Server 2016+) [^x86_32-floats-return-ABI]
-`i686-unknown-linux-gnu` | 32-bit Linux (kernel 3.2+, glibc 2.17+) [^x86_32-floats-return-ABI]
+`i686-pc-windows-gnu` | 32-bit MinGW (Windows 10+, Windows Server 2016+, Pentium 4) [^x86_32-floats-return-ABI]
+`i686-pc-windows-msvc` | 32-bit MSVC (Windows 10+, Windows Server 2016+, Pentium 4) [^x86_32-floats-return-ABI]
+`i686-unknown-linux-gnu` | 32-bit Linux (kernel 3.2+, glibc 2.17+, Pentium 4) [^x86_32-floats-return-ABI]
 [`x86_64-apple-darwin`](platform-support/apple-darwin.md) | 64-bit macOS (10.12+, Sierra+)
 `x86_64-pc-windows-gnu` | 64-bit MinGW (Windows 10+, Windows Server 2016+)
 `x86_64-pc-windows-msvc` | 64-bit MSVC (Windows 10+, Windows Server 2016+)
@@ -162,14 +162,14 @@ target | std | notes
 [`armv7a-none-eabi`](platform-support/arm-none-eabi.md) | * | Bare Armv7-A
 [`armv7r-none-eabi`](platform-support/armv7r-none-eabi.md) | * | Bare Armv7-R
 [`armv7r-none-eabihf`](platform-support/armv7r-none-eabi.md) | * | Bare Armv7-R, hardfloat
-`i586-pc-windows-msvc` | * | 32-bit Windows w/o SSE [^x86_32-floats-x87]
-`i586-unknown-linux-gnu` | ✓ | 32-bit Linux w/o SSE (kernel 3.2, glibc 2.17) [^x86_32-floats-x87]
-`i586-unknown-linux-musl` | ✓ | 32-bit Linux w/o SSE, musl 1.2.3 [^x86_32-floats-x87]
-[`i686-linux-android`](platform-support/android.md) | ✓ | 32-bit x86 Android [^x86_32-floats-return-ABI]
-[`i686-pc-windows-gnullvm`](platform-support/pc-windows-gnullvm.md) | ✓ | 32-bit x86 MinGW (Windows 10+), LLVM ABI [^x86_32-floats-return-ABI]
-[`i686-unknown-freebsd`](platform-support/freebsd.md) | ✓ | 32-bit x86 FreeBSD [^x86_32-floats-return-ABI]
-`i686-unknown-linux-musl` | ✓ | 32-bit Linux with musl 1.2.3 [^x86_32-floats-return-ABI]
-[`i686-unknown-uefi`](platform-support/unknown-uefi.md) | ? | 32-bit UEFI
+`i586-pc-windows-msvc` | * | 32-bit Windows (original Pentium) [^x86_32-floats-x87]
+`i586-unknown-linux-gnu` | ✓ | 32-bit Linux (kernel 3.2, glibc 2.17, original Pentium) [^x86_32-floats-x87]
+`i586-unknown-linux-musl` | ✓ | 32-bit Linux (musl 1.2.3, original Pentium) [^x86_32-floats-x87]
+[`i686-linux-android`](platform-support/android.md) | ✓ | 32-bit x86 Android ([PentiumPro with SSE](https://developer.android.com/ndk/guides/abis.html#x86)) [^x86_32-floats-return-ABI]
+[`i686-pc-windows-gnullvm`](platform-support/pc-windows-gnullvm.md) | ✓ | 32-bit x86 MinGW (Windows 10+, Pentium 4), LLVM ABI [^x86_32-floats-return-ABI]
+[`i686-unknown-freebsd`](platform-support/freebsd.md) | ✓ | 32-bit x86 FreeBSD (Pentium 4) [^x86_32-floats-return-ABI]
+`i686-unknown-linux-musl` | ✓ | 32-bit Linux with musl 1.2.3 (Pentium 4) [^x86_32-floats-return-ABI]
+[`i686-unknown-uefi`](platform-support/unknown-uefi.md) | ? (Pentium 4, softfloat) | 32-bit UEFI
 [`loongarch64-unknown-none`](platform-support/loongarch-none.md) | * | LoongArch64 Bare-metal (LP64D ABI)
 [`loongarch64-unknown-none-softfloat`](platform-support/loongarch-none.md) | * | LoongArch64 Bare-metal (LP64S ABI)
 [`nvptx64-nvidia-cuda`](platform-support/nvptx64-nvidia-cuda.md) | * | --emit=asm generates PTX code that [runs on NVIDIA GPUs]
@@ -307,15 +307,15 @@ target | std | host | notes
 `csky-unknown-linux-gnuabiv2hf` | ✓ |  | C-SKY abiv2 Linux, hardfloat (little endian)
 [`hexagon-unknown-linux-musl`](platform-support/hexagon-unknown-linux-musl.md) | ✓ | | Hexagon Linux with musl 1.2.3
 [`hexagon-unknown-none-elf`](platform-support/hexagon-unknown-none-elf.md)| * | | Bare Hexagon (v60+, HVX)
-[`i386-apple-ios`](platform-support/apple-ios.md) | ✓ |  | 32-bit x86 iOS [^x86_32-floats-return-ABI]
-[`i586-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS  [^x86_32-floats-return-ABI]
-[`i586-unknown-netbsd`](platform-support/netbsd.md) | ✓ |  | 32-bit x86, restricted to Pentium
-[`i686-apple-darwin`](platform-support/apple-darwin.md) | ✓ | ✓ | 32-bit macOS (10.12+, Sierra+) [^x86_32-floats-return-ABI]
-`i686-unknown-haiku` | ✓ | ✓ | 32-bit Haiku [^x86_32-floats-return-ABI]
-[`i686-unknown-hurd-gnu`](platform-support/hurd.md) | ✓ | ✓ | 32-bit GNU/Hurd [^x86_32-floats-return-ABI]
-[`i686-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | NetBSD/i386 with SSE2 [^x86_32-floats-return-ABI]
-[`i686-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | 32-bit OpenBSD [^x86_32-floats-return-ABI]
-[`i686-unknown-redox`](platform-support/redox.md) | ✓ |  | i686 Redox OS
+[`i386-apple-ios`](platform-support/apple-ios.md) | ✓ |  | 32-bit x86 iOS (Penryn) [^x86_32-floats-return-ABI]
+[`i586-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS (Pentium 4) [^x86_32-floats-return-ABI]
+[`i586-unknown-netbsd`](platform-support/netbsd.md) | ✓ |  | 32-bit x86 (original Pentium) [^x86_32-floats-x87]
+[`i686-apple-darwin`](platform-support/apple-darwin.md) | ✓ | ✓ | 32-bit macOS (10.12+, Sierra+, Penryn) [^x86_32-floats-return-ABI]
+`i686-unknown-haiku` | ✓ | ✓ | 32-bit Haiku (Pentium 4) [^x86_32-floats-return-ABI]
+[`i686-unknown-hurd-gnu`](platform-support/hurd.md) | ✓ | ✓ | 32-bit GNU/Hurd (PentiumPro) [^x86_32-floats-x87]
+[`i686-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | NetBSD/i386 (Pentium 4) [^x86_32-floats-return-ABI]
+[`i686-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | 32-bit OpenBSD (Pentium 4) [^x86_32-floats-return-ABI]
+[`i686-unknown-redox`](platform-support/redox.md) | ✓ |  | i686 Redox OS (PentiumPro) [^x86_32-floats-x87]
 `i686-uwp-windows-gnu` | ✓ |  | [^x86_32-floats-return-ABI]
 [`i686-uwp-windows-msvc`](platform-support/uwp-windows-msvc.md) | ✓ |  | [^x86_32-floats-return-ABI]
 [`i686-win7-windows-gnu`](platform-support/win7-windows-gnu.md) | ✓ |   | 32-bit Windows 7 support [^x86_32-floats-return-ABI]
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 7853e311a04..0d4ff6e7aa5 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1104,17 +1104,29 @@ fn clean_args_from_types_and_names<'tcx>(
     types: &[hir::Ty<'tcx>],
     names: &[Ident],
 ) -> Arguments {
+    fn nonempty_name(ident: &Ident) -> Option<Symbol> {
+        if ident.name == kw::Underscore || ident.name == kw::Empty {
+            None
+        } else {
+            Some(ident.name)
+        }
+    }
+
+    // If at least one argument has a name, use `_` as the name of unnamed
+    // arguments. Otherwise omit argument names.
+    let default_name = if names.iter().any(|ident| nonempty_name(ident).is_some()) {
+        kw::Underscore
+    } else {
+        kw::Empty
+    };
+
     Arguments {
         values: types
             .iter()
             .enumerate()
             .map(|(i, ty)| Argument {
                 type_: clean_ty(ty, cx),
-                name: names
-                    .get(i)
-                    .map(|ident| ident.name)
-                    .filter(|ident| !ident.is_empty())
-                    .unwrap_or(kw::Underscore),
+                name: names.get(i).and_then(nonempty_name).unwrap_or(default_name),
                 is_const: false,
             })
             .collect(),
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index cfba7895208..c6fb70eee08 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -9,8 +9,8 @@ use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::DiagCtxtHandle;
 use rustc_session::config::{
     self, CodegenOptions, CrateType, ErrorOutputType, Externs, Input, JsonUnusedExterns,
-    UnstableOptions, get_cmd_lint_options, nightly_options, parse_crate_types_from_list,
-    parse_externs, parse_target_triple,
+    OptionsTargetModifiers, UnstableOptions, get_cmd_lint_options, nightly_options,
+    parse_crate_types_from_list, parse_externs, parse_target_triple,
 };
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
@@ -389,8 +389,9 @@ impl Options {
             config::parse_error_format(early_dcx, matches, color, json_color, json_rendered);
         let diagnostic_width = matches.opt_get("diagnostic-width").unwrap_or_default();
 
-        let codegen_options = CodegenOptions::build(early_dcx, matches);
-        let unstable_opts = UnstableOptions::build(early_dcx, matches);
+        let mut target_modifiers = BTreeMap::<OptionsTargetModifiers, String>::new();
+        let codegen_options = CodegenOptions::build(early_dcx, matches, &mut target_modifiers);
+        let unstable_opts = UnstableOptions::build(early_dcx, matches, &mut target_modifiers);
 
         let remap_path_prefix = match parse_remap_path_prefix(matches) {
             Ok(prefix_mappings) => prefix_mappings,
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 20a8dc72491..ffd457c8273 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -1408,7 +1408,9 @@ impl clean::Arguments {
     ) -> impl Display + 'a + Captures<'tcx> {
         fmt::from_fn(move |f| {
             for (i, input) in self.values.iter().enumerate() {
-                write!(f, "{}: ", input.name)?;
+                if !input.name.is_empty() {
+                    write!(f, "{}: ", input.name)?;
+                }
                 input.type_.print(cx).fmt(f)?;
                 if i + 1 < self.values.len() {
                     write!(f, ", ")?;
diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs
index 8c96554738e..452a2e9a9d5 100644
--- a/src/tools/compiletest/src/header.rs
+++ b/src/tools/compiletest/src/header.rs
@@ -882,14 +882,6 @@ fn iter_header(
         }
         let ln = ln.trim();
 
-        // Assume that any directives will be found before the first module or function. This
-        // doesn't seem to be an optimization with a warm page cache. Maybe with a cold one.
-        // FIXME(jieyouxu): this will cause `//@` directives in the rest of the test file to
-        // not be checked.
-        if ln.starts_with("fn") || ln.starts_with("mod") {
-            return;
-        }
-
         let Some(directive_line) = line_directive(line_number, comment, ln) else {
             continue;
         };
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index ca48abda5fc..0e2da2b02ca 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -1417,9 +1417,7 @@ impl<'test> TestCx<'test> {
     }
 
     fn is_rustdoc(&self) -> bool {
-        self.config.src_base.ends_with("rustdoc-ui")
-            || self.config.src_base.ends_with("rustdoc-js")
-            || self.config.src_base.ends_with("rustdoc-json")
+        matches!(self.config.suite.as_str(), "rustdoc-ui" | "rustdoc-js" | "rustdoc-json")
     }
 
     fn get_mir_dump_dir(&self) -> PathBuf {
diff --git a/src/tools/compiletest/src/runtest/rustdoc_json.rs b/src/tools/compiletest/src/runtest/rustdoc_json.rs
index 31fdb0a5d13..bf7eb2e109a 100644
--- a/src/tools/compiletest/src/runtest/rustdoc_json.rs
+++ b/src/tools/compiletest/src/runtest/rustdoc_json.rs
@@ -16,13 +16,12 @@ impl TestCx<'_> {
             self.fatal_proc_rec("rustdoc failed!", &proc_res);
         }
 
-        let root = self.config.find_rust_src_root().unwrap();
         let mut json_out = out_dir.join(self.testpaths.file.file_stem().unwrap());
         json_out.set_extension("json");
         let res = self.run_command_to_procres(
             Command::new(self.config.jsondocck_path.as_ref().unwrap())
                 .arg("--doc-dir")
-                .arg(root.join(&out_dir))
+                .arg(&out_dir)
                 .arg("--template")
                 .arg(&self.testpaths.file),
         );
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_allocs.rs b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_allocs.rs
new file mode 100644
index 00000000000..5a997ad8ec4
--- /dev/null
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_allocs.rs
@@ -0,0 +1,5 @@
+fn main() {
+    unsafe {
+        (&1_u8 as *const u8).offset_from(&2_u8); //~ERROR: not both derived from the same allocation
+    }
+}
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_allocs.stderr b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_allocs.stderr
new file mode 100644
index 00000000000..34d7c6a8021
--- /dev/null
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_allocs.stderr
@@ -0,0 +1,15 @@
+error: Undefined Behavior: `ptr_offset_from` called on two different pointers that are not both derived from the same allocation
+  --> tests/fail/intrinsics/ptr_offset_from_different_allocs.rs:LL:CC
+   |
+LL |         (&1_u8 as *const u8).offset_from(&2_u8);
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on two different pointers that are not both derived from the same allocation
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at tests/fail/intrinsics/ptr_offset_from_different_allocs.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_ints.rs b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_ints.rs
index 0acda559d3a..0d34e711ca7 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_ints.rs
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_ints.rs
@@ -15,6 +15,6 @@ fn main() {
         let _ = p1.byte_offset_from(p1);
 
         // UB because different pointers.
-        let _ = p1.byte_offset_from(p2); //~ERROR: no provenance
+        let _ = p1.byte_offset_from(p2); //~ERROR: not both derived from the same allocation
     }
 }
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_ints.stderr b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_ints.stderr
index 7ef66390fcd..897945d6d5d 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_ints.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_different_ints.stderr
@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds `offset_from` origin: expected a pointer to the end of 1 byte of memory, but got 0xb[noalloc] which is a dangling pointer (it has no provenance)
+error: Undefined Behavior: `ptr_offset_from` called on two different pointers that are not both derived from the same allocation
   --> tests/fail/intrinsics/ptr_offset_from_different_ints.rs:LL:CC
    |
 LL |         let _ = p1.byte_offset_from(p2);
-   |                 ^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds `offset_from` origin: expected a pointer to the end of 1 byte of memory, but got 0xb[noalloc] which is a dangling pointer (it has no provenance)
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on two different pointers that are not both derived from the same allocation
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_oob.rs b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_oob.rs
new file mode 100644
index 00000000000..06f6b7a0117
--- /dev/null
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_oob.rs
@@ -0,0 +1,7 @@
+fn main() {
+    let mem = [0u8; 1];
+    let ptr = mem.as_ptr();
+    unsafe {
+        ptr.wrapping_add(4).offset_from(ptr); //~ERROR: the memory range between them is not in-bounds of an allocation
+    }
+}
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_oob.stderr b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_oob.stderr
new file mode 100644
index 00000000000..67df633bef5
--- /dev/null
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_offset_from_oob.stderr
@@ -0,0 +1,15 @@
+error: Undefined Behavior: `ptr_offset_from` called on two different pointers where the memory range between them is not in-bounds of an allocation
+  --> tests/fail/intrinsics/ptr_offset_from_oob.rs:LL:CC
+   |
+LL |         ptr.wrapping_add(4).offset_from(ptr);
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on two different pointers where the memory range between them is not in-bounds of an allocation
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at tests/fail/intrinsics/ptr_offset_from_oob.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+
diff --git a/src/tools/tidy/src/issues.txt b/src/tools/tidy/src/issues.txt
index 839d23fb9a7..17786ed6d2f 100644
--- a/src/tools/tidy/src/issues.txt
+++ b/src/tools/tidy/src/issues.txt
@@ -3146,7 +3146,6 @@ ui/nll/issue-97997.rs
 ui/nll/issue-98170.rs
 ui/nll/issue-98589-closures-relate-named-regions.rs
 ui/nll/issue-98693.rs
-ui/nll/polonius/issue-46589.rs
 ui/nll/relate_tys/issue-48071.rs
 ui/nll/ty-outlives/issue-53789-1.rs
 ui/nll/ty-outlives/issue-53789-2.rs
diff --git a/tests/assembly/small_data_threshold.rs b/tests/assembly/small_data_threshold.rs
index d3ba144600e..bed515915b8 100644
--- a/tests/assembly/small_data_threshold.rs
+++ b/tests/assembly/small_data_threshold.rs
@@ -58,35 +58,35 @@ static mut Z: u64 = 0;
 // Currently, only MIPS and RISCV successfully put any objects in the small data
 // sections so the U/V/W/X tests are skipped on Hexagon and M68K
 
-//@ RISCV: .section .sdata
-//@ RISCV-NOT: .section
-//@ RISCV: U:
-//@ RISCV: .section .sbss
-//@ RISCV-NOT: .section
-//@ RISCV: V:
-//@ RISCV: .section .sdata
-//@ RISCV-NOT: .section
-//@ RISCV: W:
-//@ RISCV: .section .sbss
-//@ RISCV-NOT: .section
-//@ RISCV: X:
+// RISCV: .section .sdata
+// RISCV-NOT: .section
+// RISCV: U:
+// RISCV: .section .sbss
+// RISCV-NOT: .section
+// RISCV: V:
+// RISCV: .section .sdata
+// RISCV-NOT: .section
+// RISCV: W:
+// RISCV: .section .sbss
+// RISCV-NOT: .section
+// RISCV: X:
 
-//@ MIPS: .section .sdata
-//@ MIPS-NOT: .section
-//@ MIPS: U:
-//@ MIPS: .section .sbss
-//@ MIPS-NOT: .section
-//@ MIPS: V:
-//@ MIPS: .section .sdata
-//@ MIPS-NOT: .section
-//@ MIPS: W:
-//@ MIPS: .section .sbss
-//@ MIPS-NOT: .section
-//@ MIPS: X:
+// MIPS: .section .sdata
+// MIPS-NOT: .section
+// MIPS: U:
+// MIPS: .section .sbss
+// MIPS-NOT: .section
+// MIPS: V:
+// MIPS: .section .sdata
+// MIPS-NOT: .section
+// MIPS: W:
+// MIPS: .section .sbss
+// MIPS-NOT: .section
+// MIPS: X:
 
-//@ CHECK: .section .data.Y,
-//@ CHECK-NOT: .section
-//@ CHECK: Y:
-//@ CHECK: .section .bss.Z,
-//@ CHECK-NOT: .section
-//@ CHECK: Z:
+// CHECK: .section .data.Y,
+// CHECK-NOT: .section
+// CHECK: Y:
+// CHECK: .section .bss.Z,
+// CHECK-NOT: .section
+// CHECK: Z:
diff --git a/tests/codegen/intrinsics/cold_path2.rs b/tests/codegen/intrinsics/cold_path2.rs
new file mode 100644
index 00000000000..1e7e0478f4f
--- /dev/null
+++ b/tests/codegen/intrinsics/cold_path2.rs
@@ -0,0 +1,36 @@
+//@ compile-flags: -O
+#![crate_type = "lib"]
+#![feature(core_intrinsics)]
+
+use std::intrinsics::cold_path;
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_a() {
+    println!("path a");
+}
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_b() {
+    println!("path b");
+}
+
+#[no_mangle]
+pub fn test(x: Option<bool>) {
+    if let Some(_) = x {
+        path_a();
+    } else {
+        cold_path();
+        path_b();
+    }
+
+    // CHECK-LABEL: @test(
+    // CHECK: br i1 %1, label %bb2, label %bb1, !prof ![[NUM:[0-9]+]]
+    // CHECK: bb1:
+    // CHECK: path_a
+    // CHECK: bb2:
+    // CHECK: path_b
+}
+
+// CHECK: ![[NUM]] = !{!"branch_weights", {{(!"expected", )?}}i32 1, i32 2000}
diff --git a/tests/codegen/intrinsics/cold_path3.rs b/tests/codegen/intrinsics/cold_path3.rs
new file mode 100644
index 00000000000..bf3347de665
--- /dev/null
+++ b/tests/codegen/intrinsics/cold_path3.rs
@@ -0,0 +1,87 @@
+//@ compile-flags: -O
+#![crate_type = "lib"]
+#![feature(core_intrinsics)]
+
+use std::intrinsics::cold_path;
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_a() {
+    println!("path a");
+}
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_b() {
+    println!("path b");
+}
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_c() {
+    println!("path c");
+}
+
+#[inline(never)]
+#[no_mangle]
+pub fn path_d() {
+    println!("path d");
+}
+
+#[no_mangle]
+pub fn test(x: Option<u32>) {
+    match x {
+        Some(0) => path_a(),
+        Some(1) => {
+            cold_path();
+            path_b()
+        }
+        Some(2) => path_c(),
+        Some(3) => {
+            cold_path();
+            path_d()
+        }
+        _ => path_a(),
+    }
+
+    // CHECK-LABEL: @test(
+    // CHECK: switch i32 %1, label %bb1 [
+    // CHECK: i32 0, label %bb6
+    // CHECK: i32 1, label %bb5
+    // CHECK: i32 2, label %bb4
+    // CHECK: i32 3, label %bb3
+    // CHECK: ], !prof ![[NUM1:[0-9]+]]
+}
+
+#[no_mangle]
+pub fn test2(x: Option<u32>) {
+    match x {
+        Some(10) => path_a(),
+        Some(11) => {
+            cold_path();
+            path_b()
+        }
+        Some(12) => {
+            unsafe { core::intrinsics::unreachable() };
+            path_c()
+        }
+        Some(13) => {
+            cold_path();
+            path_d()
+        }
+        _ => {
+            cold_path();
+            path_a()
+        }
+    }
+
+    // CHECK-LABEL: @test2(
+    // CHECK: switch i32 %1, label %bb1 [
+    // CHECK: i32 10, label %bb5
+    // CHECK: i32 11, label %bb4
+    // CHECK: i32 13, label %bb3
+    // CHECK: ], !prof ![[NUM2:[0-9]+]]
+}
+
+// CHECK: ![[NUM1]] = !{!"branch_weights", i32 2000, i32 2000, i32 1, i32 2000, i32 1}
+// CHECK: ![[NUM2]] = !{!"branch_weights", i32 1, i32 2000, i32 1, i32 1}
diff --git a/tests/rustdoc/assoc-consts.rs b/tests/rustdoc/assoc-consts.rs
index cb8e839541c..247b5b180a8 100644
--- a/tests/rustdoc/assoc-consts.rs
+++ b/tests/rustdoc/assoc-consts.rs
@@ -45,7 +45,7 @@ pub fn f(_: &(ToString + 'static)) {}
 
 impl Bar {
     //@ has assoc_consts/struct.Bar.html '//*[@id="associatedconstant.F"]' \
-    //      "const F: fn(_: &(dyn ToString + 'static))"
+    //      "const F: fn(&(dyn ToString + 'static))"
     pub const F: fn(_: &(ToString + 'static)) = f;
 }
 
diff --git a/tests/rustdoc/fn-pointer-arg-name.rs b/tests/rustdoc/fn-pointer-arg-name.rs
index 3bde6e9ecfa..0ee1964511a 100644
--- a/tests/rustdoc/fn-pointer-arg-name.rs
+++ b/tests/rustdoc/fn-pointer-arg-name.rs
@@ -3,3 +3,11 @@
 //@ has foo/fn.f.html
 //@ has - '//pre[@class="rust item-decl"]' 'pub fn f(callback: fn(len: usize, foo: u32))'
 pub fn f(callback: fn(len: usize, foo: u32)) {}
+
+//@ has foo/fn.g.html
+//@ has - '//pre[@class="rust item-decl"]' 'pub fn g(_: fn(usize, u32))'
+pub fn g(_: fn(usize, _: u32)) {}
+
+//@ has foo/fn.mixed.html
+//@ has - '//pre[@class="rust item-decl"]' 'pub fn mixed(_: fn(_: usize, foo: u32))'
+pub fn mixed(_: fn(usize, foo: u32)) {}
diff --git a/tests/rustdoc/inherent-projections.rs b/tests/rustdoc/inherent-projections.rs
index 4fc769f70f5..ced4db9a490 100644
--- a/tests/rustdoc/inherent-projections.rs
+++ b/tests/rustdoc/inherent-projections.rs
@@ -13,7 +13,7 @@ impl Owner {
 }
 
 // Make sure we handle bound vars correctly.
-//@ has 'inherent_projections/fn.user.html' '//pre[@class="rust item-decl"]' "user(_: for<'a> fn(_: Carrier<'a>::Focus))"
+//@ has 'inherent_projections/fn.user.html' '//pre[@class="rust item-decl"]' "user(_: for<'a> fn(Carrier<'a>::Focus))"
 pub fn user(_: for<'a> fn(Carrier<'a>::Focus)) {}
 
 pub struct Carrier<'a>(&'a ());
diff --git a/tests/rustdoc/macro-higher-kinded-function.rs b/tests/rustdoc/macro-higher-kinded-function.rs
index f14125d1309..738ea8fb3f1 100644
--- a/tests/rustdoc/macro-higher-kinded-function.rs
+++ b/tests/rustdoc/macro-higher-kinded-function.rs
@@ -11,10 +11,10 @@ macro_rules! gen {
 }
 
 //@ has 'foo/struct.Providers.html'
-//@ has - '//*[@class="rust item-decl"]//code' "pub a: for<'tcx> fn(_: TyCtxt<'tcx>, _: u8) -> i8,"
-//@ has - '//*[@class="rust item-decl"]//code' "pub b: for<'tcx> fn(_: TyCtxt<'tcx>, _: u16) -> i16,"
-//@ has - '//*[@id="structfield.a"]/code' "a: for<'tcx> fn(_: TyCtxt<'tcx>, _: u8) -> i8"
-//@ has - '//*[@id="structfield.b"]/code' "b: for<'tcx> fn(_: TyCtxt<'tcx>, _: u16) -> i16"
+//@ has - '//*[@class="rust item-decl"]//code' "pub a: for<'tcx> fn(TyCtxt<'tcx>, u8) -> i8,"
+//@ has - '//*[@class="rust item-decl"]//code' "pub b: for<'tcx> fn(TyCtxt<'tcx>, u16) -> i16,"
+//@ has - '//*[@id="structfield.a"]/code' "a: for<'tcx> fn(TyCtxt<'tcx>, u8) -> i8"
+//@ has - '//*[@id="structfield.b"]/code' "b: for<'tcx> fn(TyCtxt<'tcx>, u16) -> i16"
 gen! {
     (a, 'tcx, [u8], [i8])
     (b, 'tcx, [u16], [i16])
diff --git a/tests/ui/const-ptr/forbidden_slices.stderr b/tests/ui/const-ptr/forbidden_slices.stderr
index fad078ad2b2..2e0c04dcf1e 100644
--- a/tests/ui/const-ptr/forbidden_slices.stderr
+++ b/tests/ui/const-ptr/forbidden_slices.stderr
@@ -190,7 +190,7 @@ LL |     from_ptr_range(ptr..ptr.add(1))
 error[E0080]: could not evaluate static initializer
   --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
    |
-   = note: `ptr_offset_from_unsigned` called on pointers into different allocations
+   = note: `ptr_offset_from_unsigned` called on two different pointers that are not both derived from the same allocation
    |
 note: inside `std::ptr::const_ptr::<impl *const u32>::sub_ptr`
   --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
@@ -205,7 +205,7 @@ LL | pub static R9: &[u32] = unsafe { from_ptr_range(&D0..(&D0 as *const u32).ad
 error[E0080]: could not evaluate static initializer
   --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
    |
-   = note: `ptr_offset_from_unsigned` called on pointers into different allocations
+   = note: `ptr_offset_from_unsigned` called on two different pointers that are not both derived from the same allocation
    |
 note: inside `std::ptr::const_ptr::<impl *const u32>::sub_ptr`
   --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
diff --git a/tests/ui/consts/offset_from_ub.rs b/tests/ui/consts/offset_from_ub.rs
index 0232b03a813..88356900605 100644
--- a/tests/ui/consts/offset_from_ub.rs
+++ b/tests/ui/consts/offset_from_ub.rs
@@ -17,7 +17,7 @@ pub const DIFFERENT_ALLOC: usize = {
     let uninit2 = std::mem::MaybeUninit::<Struct>::uninit();
     let field_ptr: *const Struct = &uninit2 as *const _ as *const Struct;
     let offset = unsafe { ptr_offset_from(field_ptr, base_ptr) }; //~ERROR evaluation of constant value failed
-    //~| pointers into different allocations
+    //~| not both derived from the same allocation
     offset as usize
 };
 
@@ -37,7 +37,7 @@ pub const DIFFERENT_INT: isize = { // offset_from with two different integers: l
     let ptr1 = 8 as *const u8;
     let ptr2 = 16 as *const u8;
     unsafe { ptr_offset_from(ptr2, ptr1) } //~ERROR evaluation of constant value failed
-    //~| dangling pointer
+    //~| not both derived from the same allocation
 };
 
 const OUT_OF_BOUNDS_1: isize = {
@@ -46,7 +46,7 @@ const OUT_OF_BOUNDS_1: isize = {
     let end_ptr = (start_ptr).wrapping_add(length);
     // First ptr is out of bounds
     unsafe { ptr_offset_from(end_ptr, start_ptr) } //~ERROR evaluation of constant value failed
-    //~| expected a pointer to 10 bytes of memory
+    //~| the memory range between them is not in-bounds of an allocation
 };
 
 const OUT_OF_BOUNDS_2: isize = {
@@ -55,7 +55,7 @@ const OUT_OF_BOUNDS_2: isize = {
     let end_ptr = (start_ptr).wrapping_add(length);
     // Second ptr is out of bounds
     unsafe { ptr_offset_from(start_ptr, end_ptr) } //~ERROR evaluation of constant value failed
-    //~| expected a pointer to the end of 10 bytes of memory
+    //~| the memory range between them is not in-bounds of an allocation
 };
 
 pub const DIFFERENT_ALLOC_UNSIGNED: usize = {
@@ -64,7 +64,7 @@ pub const DIFFERENT_ALLOC_UNSIGNED: usize = {
     let uninit2 = std::mem::MaybeUninit::<Struct>::uninit();
     let field_ptr: *const Struct = &uninit2 as *const _ as *const Struct;
     unsafe { ptr_offset_from_unsigned(field_ptr, base_ptr) } //~ERROR evaluation of constant value failed
-    //~| pointers into different allocations
+    //~| not both derived from the same allocation
 };
 
 pub const TOO_FAR_APART1: isize = {
diff --git a/tests/ui/consts/offset_from_ub.stderr b/tests/ui/consts/offset_from_ub.stderr
index ac4597ff011..1379365cc25 100644
--- a/tests/ui/consts/offset_from_ub.stderr
+++ b/tests/ui/consts/offset_from_ub.stderr
@@ -2,12 +2,12 @@ error[E0080]: evaluation of constant value failed
   --> $DIR/offset_from_ub.rs:19:27
    |
 LL |     let offset = unsafe { ptr_offset_from(field_ptr, base_ptr) };
-   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on pointers into different allocations
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on two different pointers that are not both derived from the same allocation
 
 error[E0080]: evaluation of constant value failed
   --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
    |
-   = note: `ptr_offset_from` called on pointers into different allocations
+   = note: `ptr_offset_from` called on two different pointers that are not both derived from the same allocation
    |
 note: inside `std::ptr::const_ptr::<impl *const u8>::offset_from`
   --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
@@ -27,25 +27,25 @@ error[E0080]: evaluation of constant value failed
   --> $DIR/offset_from_ub.rs:39:14
    |
 LL |     unsafe { ptr_offset_from(ptr2, ptr1) }
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds `offset_from` origin: expected a pointer to $BYTES bytes of memory, but got 0x8[noalloc] which is a dangling pointer (it has no provenance)
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on two different pointers that are not both derived from the same allocation
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/offset_from_ub.rs:48:14
    |
 LL |     unsafe { ptr_offset_from(end_ptr, start_ptr) }
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds `offset_from` origin: expected a pointer to $BYTES bytes of memory, but got ALLOC0 which is only $BYTES bytes from the end of the allocation
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on two different pointers where the memory range between them is not in-bounds of an allocation
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/offset_from_ub.rs:57:14
    |
 LL |     unsafe { ptr_offset_from(start_ptr, end_ptr) }
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds `offset_from` origin: expected a pointer to the end of $BYTES bytes of memory, but got ALLOC1+0xa which does not have enough space to the beginning of the allocation
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from` called on two different pointers where the memory range between them is not in-bounds of an allocation
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/offset_from_ub.rs:66:14
    |
 LL |     unsafe { ptr_offset_from_unsigned(field_ptr, base_ptr) }
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from_unsigned` called on pointers into different allocations
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ptr_offset_from_unsigned` called on two different pointers that are not both derived from the same allocation
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/offset_from_ub.rs:73:14
@@ -80,7 +80,7 @@ LL |     unsafe { ptr_offset_from_unsigned(ptr2, ptr1) }
 error[E0080]: evaluation of constant value failed
   --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
    |
-   = note: out-of-bounds `offset_from` origin: expected a pointer to $BYTES bytes of memory, but got a null pointer
+   = note: `ptr_offset_from` called on two different pointers that are not both derived from the same allocation
    |
 note: inside `std::ptr::const_ptr::<impl *const u8>::offset_from`
   --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
diff --git a/tests/ui/lazy-type-alias/def-site-param-defaults-wf.rs b/tests/ui/lazy-type-alias/def-site-param-defaults-wf.rs
new file mode 100644
index 00000000000..90bb0a294f8
--- /dev/null
+++ b/tests/ui/lazy-type-alias/def-site-param-defaults-wf.rs
@@ -0,0 +1,9 @@
+//! Ensure that we check generic parameter defaults for well-formedness at the definition site.
+#![feature(lazy_type_alias)]
+#![allow(incomplete_features)]
+
+type Alias<T = Vec<str>, const N: usize = {0 - 1}> = T;
+//~^ ERROR evaluation of constant value failed
+//~| ERROR the size for values of type `str` cannot be known at compilation time
+
+fn main() {}
diff --git a/tests/ui/lazy-type-alias/def-site-param-defaults-wf.stderr b/tests/ui/lazy-type-alias/def-site-param-defaults-wf.stderr
new file mode 100644
index 00000000000..da0021ccaf4
--- /dev/null
+++ b/tests/ui/lazy-type-alias/def-site-param-defaults-wf.stderr
@@ -0,0 +1,20 @@
+error[E0080]: evaluation of constant value failed
+  --> $DIR/def-site-param-defaults-wf.rs:5:44
+   |
+LL | type Alias<T = Vec<str>, const N: usize = {0 - 1}> = T;
+   |                                            ^^^^^ attempt to compute `0_usize - 1_usize`, which would overflow
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/def-site-param-defaults-wf.rs:5:16
+   |
+LL | type Alias<T = Vec<str>, const N: usize = {0 - 1}> = T;
+   |                ^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by an implicit `Sized` bound in `Vec`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0080, E0277.
+For more information about an error, try `rustc --explain E0080`.
diff --git a/tests/ui/lazy-type-alias/def-site-predicates-wf.rs b/tests/ui/lazy-type-alias/def-site-predicates-wf.rs
new file mode 100644
index 00000000000..5d9235347cb
--- /dev/null
+++ b/tests/ui/lazy-type-alias/def-site-predicates-wf.rs
@@ -0,0 +1,13 @@
+//! Ensure that we check the predicates at the definition site for well-formedness.
+#![feature(lazy_type_alias)]
+#![allow(incomplete_features)]
+
+type Alias0 = ()
+where
+    Vec<str>:; //~ ERROR the size for values of type `str` cannot be known at compilation time
+
+type Alias1 = ()
+where
+    Vec<str>: Sized; //~ ERROR the size for values of type `str` cannot be known at compilation time
+
+fn main() {}
diff --git a/tests/ui/lazy-type-alias/def-site-predicates-wf.stderr b/tests/ui/lazy-type-alias/def-site-predicates-wf.stderr
new file mode 100644
index 00000000000..b44e702c35c
--- /dev/null
+++ b/tests/ui/lazy-type-alias/def-site-predicates-wf.stderr
@@ -0,0 +1,23 @@
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/def-site-predicates-wf.rs:7:5
+   |
+LL |     Vec<str>:;
+   |     ^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by an implicit `Sized` bound in `Vec`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/def-site-predicates-wf.rs:11:15
+   |
+LL |     Vec<str>: Sized;
+   |               ^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by an implicit `Sized` bound in `Vec`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/lifetimes/tail-expr-lock-poisoning.rs b/tests/ui/lifetimes/tail-expr-lock-poisoning.rs
index d7c7b2e2414..1c838a9e5e1 100644
--- a/tests/ui/lifetimes/tail-expr-lock-poisoning.rs
+++ b/tests/ui/lifetimes/tail-expr-lock-poisoning.rs
@@ -1,5 +1,4 @@
 //@ revisions: edition2021 edition2024
-//@ ignore-wasm no panic support
 //@ needs-subprocess
 //@ [edition2024] edition: 2024
 //@ run-pass
diff --git a/tests/ui/nll/get_default.legacy.stderr b/tests/ui/nll/get_default.legacy.stderr
new file mode 100644
index 00000000000..699250312dc
--- /dev/null
+++ b/tests/ui/nll/get_default.legacy.stderr
@@ -0,0 +1,18 @@
+error[E0502]: cannot borrow `*map` as mutable because it is also borrowed as immutable
+  --> $DIR/get_default.rs:35:17
+   |
+LL | fn err(map: &mut Map) -> &String {
+   |             - let's call the lifetime of this reference `'1`
+LL |     loop {
+LL |         match map.get() {
+   |               --- immutable borrow occurs here
+LL |             Some(v) => {
+LL |                 map.set(String::new()); // We always expect an error here.
+   |                 ^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |
+LL |                 return v;
+   |                        - returning this value requires that `*map` is borrowed for `'1`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0502`.
diff --git a/tests/ui/nll/get_default.stderr b/tests/ui/nll/get_default.nll.stderr
index af79771e7e1..9b5976ca717 100644
--- a/tests/ui/nll/get_default.stderr
+++ b/tests/ui/nll/get_default.nll.stderr
@@ -1,5 +1,5 @@
 error[E0502]: cannot borrow `*map` as mutable because it is also borrowed as immutable
-  --> $DIR/get_default.rs:21:17
+  --> $DIR/get_default.rs:24:17
    |
 LL | fn ok(map: &mut Map) -> &String {
    |            - let's call the lifetime of this reference `'1`
@@ -14,7 +14,7 @@ LL |                 map.set(String::new()); // Ideally, this would not error.
    |                 ^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
 
 error[E0502]: cannot borrow `*map` as mutable because it is also borrowed as immutable
-  --> $DIR/get_default.rs:32:17
+  --> $DIR/get_default.rs:35:17
    |
 LL | fn err(map: &mut Map) -> &String {
    |             - let's call the lifetime of this reference `'1`
@@ -22,14 +22,14 @@ LL |     loop {
 LL |         match map.get() {
    |               --- immutable borrow occurs here
 LL |             Some(v) => {
-LL |                 map.set(String::new()); // Both AST and MIR error here
+LL |                 map.set(String::new()); // We always expect an error here.
    |                 ^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
 LL |
 LL |                 return v;
    |                        - returning this value requires that `*map` is borrowed for `'1`
 
 error[E0502]: cannot borrow `*map` as mutable because it is also borrowed as immutable
-  --> $DIR/get_default.rs:37:17
+  --> $DIR/get_default.rs:40:17
    |
 LL | fn err(map: &mut Map) -> &String {
    |             - let's call the lifetime of this reference `'1`
@@ -40,7 +40,7 @@ LL |         match map.get() {
 LL |                 return v;
    |                        - returning this value requires that `*map` is borrowed for `'1`
 ...
-LL |                 map.set(String::new()); // Ideally, just AST would error here
+LL |                 map.set(String::new()); // Ideally, this would not error.
    |                 ^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
 
 error: aborting due to 3 previous errors
diff --git a/tests/ui/nll/get_default.polonius.stderr b/tests/ui/nll/get_default.polonius.stderr
new file mode 100644
index 00000000000..699250312dc
--- /dev/null
+++ b/tests/ui/nll/get_default.polonius.stderr
@@ -0,0 +1,18 @@
+error[E0502]: cannot borrow `*map` as mutable because it is also borrowed as immutable
+  --> $DIR/get_default.rs:35:17
+   |
+LL | fn err(map: &mut Map) -> &String {
+   |             - let's call the lifetime of this reference `'1`
+LL |     loop {
+LL |         match map.get() {
+   |               --- immutable borrow occurs here
+LL |             Some(v) => {
+LL |                 map.set(String::new()); // We always expect an error here.
+   |                 ^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |
+LL |                 return v;
+   |                        - returning this value requires that `*map` is borrowed for `'1`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0502`.
diff --git a/tests/ui/nll/get_default.rs b/tests/ui/nll/get_default.rs
index ffac8a33da1..c3c09e9c2c5 100644
--- a/tests/ui/nll/get_default.rs
+++ b/tests/ui/nll/get_default.rs
@@ -1,7 +1,10 @@
 // Basic test for free regions in the NLL code. This test ought to
-// report an error due to a reborrowing constraint. Right now, we get
-// a variety of errors from the older, AST-based machinery (notably
-// borrowck), and then we get the NLL error at the end.
+// report an error due to a reborrowing constraint.
+
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: nll polonius legacy
+//@ [polonius] compile-flags: -Z polonius=next
+//@ [legacy] compile-flags: -Z polonius=legacy
 
 struct Map {
 }
@@ -19,7 +22,7 @@ fn ok(map: &mut Map) -> &String {
             }
             None => {
                 map.set(String::new()); // Ideally, this would not error.
-                //~^ ERROR borrowed as immutable
+                //[nll]~^ ERROR borrowed as immutable
             }
         }
     }
@@ -29,13 +32,13 @@ fn err(map: &mut Map) -> &String {
     loop {
         match map.get() {
             Some(v) => {
-                map.set(String::new()); // Both AST and MIR error here
+                map.set(String::new()); // We always expect an error here.
                 //~^ ERROR borrowed as immutable
                 return v;
             }
             None => {
-                map.set(String::new()); // Ideally, just AST would error here
-                //~^ ERROR borrowed as immutable
+                map.set(String::new()); // Ideally, this would not error.
+                //[nll]~^ ERROR borrowed as immutable
             }
         }
     }
diff --git a/tests/ui/nll/issue-46589.stderr b/tests/ui/nll/issue-46589.nll.stderr
index abf62aaa510..dc80c1d08de 100644
--- a/tests/ui/nll/issue-46589.stderr
+++ b/tests/ui/nll/issue-46589.nll.stderr
@@ -1,5 +1,5 @@
 error[E0499]: cannot borrow `**other` as mutable more than once at a time
-  --> $DIR/issue-46589.rs:23:21
+  --> $DIR/issue-46589.rs:24:21
    |
 LL |         *other = match (*other).get_self() {
    |                        -------- first mutable borrow occurs here
diff --git a/tests/ui/nll/issue-46589.rs b/tests/ui/nll/issue-46589.rs
index 417d9cab657..10aff0d7b4e 100644
--- a/tests/ui/nll/issue-46589.rs
+++ b/tests/ui/nll/issue-46589.rs
@@ -1,8 +1,9 @@
-// This tests passes in Polonius mode, so is skipped in the automated compare-mode.
-// We will manually check it passes in Polonius tests, as we can't have a test here
-// which conditionally passes depending on a test revision/compile-flags.
-
-//@ ignore-compare-mode-polonius
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: nll polonius_next polonius
+//@ [polonius_next] check-pass
+//@ [polonius_next] compile-flags: -Zpolonius=next
+//@ [polonius] check-pass
+//@ [polonius] compile-flags: -Zpolonius
 
 struct Foo;
 
@@ -21,7 +22,7 @@ impl Foo {
         *other = match (*other).get_self() {
             Some(s) => s,
             None => (*other).new_self()
-            //~^ ERROR cannot borrow `**other` as mutable more than once at a time [E0499]
+            //[nll]~^ ERROR cannot borrow `**other` as mutable more than once at a time [E0499]
         };
 
         let c = other;
diff --git a/tests/ui/nll/polonius/assignment-kills-loans.rs b/tests/ui/nll/polonius/assignment-kills-loans.rs
index 182262e5c4b..56ea9c2f1f9 100644
--- a/tests/ui/nll/polonius/assignment-kills-loans.rs
+++ b/tests/ui/nll/polonius/assignment-kills-loans.rs
@@ -4,8 +4,11 @@
 // facts only on simple assignments, but not projections, incorrectly causing errors to be emitted
 // for code accepted by NLL. They are all variations from example code in the NLL RFC.
 
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius_next polonius
 //@ check-pass
-//@ compile-flags: -Z polonius
+//@ [polonius_next] compile-flags: -Z polonius=next
+//@ [polonius] compile-flags: -Z polonius
 
 struct List<T> {
     value: T,
diff --git a/tests/ui/nll/polonius/assignment-to-differing-field.stderr b/tests/ui/nll/polonius/assignment-to-differing-field.legacy.stderr
index c46d010e4f5..cf5594dbd07 100644
--- a/tests/ui/nll/polonius/assignment-to-differing-field.stderr
+++ b/tests/ui/nll/polonius/assignment-to-differing-field.legacy.stderr
@@ -1,5 +1,5 @@
 error[E0499]: cannot borrow `list.0.value` as mutable more than once at a time
-  --> $DIR/assignment-to-differing-field.rs:20:21
+  --> $DIR/assignment-to-differing-field.rs:23:21
    |
 LL | fn assignment_to_field_projection<'a, T>(
    |                                   -- lifetime `'a` defined here
@@ -11,7 +11,7 @@ LL |             return result;
    |                    ------ returning this value requires that `list.0.value` is borrowed for `'a`
 
 error[E0499]: cannot borrow `list.0.next` as mutable more than once at a time
-  --> $DIR/assignment-to-differing-field.rs:23:26
+  --> $DIR/assignment-to-differing-field.rs:26:26
    |
 LL | fn assignment_to_field_projection<'a, T>(
    |                                   -- lifetime `'a` defined here
@@ -23,7 +23,7 @@ LL |             list.1 = n;
    |             ---------- assignment requires that `list.0.next` is borrowed for `'a`
 
 error[E0499]: cannot borrow `list.0.0.0.0.0.value` as mutable more than once at a time
-  --> $DIR/assignment-to-differing-field.rs:37:21
+  --> $DIR/assignment-to-differing-field.rs:40:21
    |
 LL | fn assignment_through_projection_chain<'a, T>(
    |                                        -- lifetime `'a` defined here
@@ -35,7 +35,7 @@ LL |             return result;
    |                    ------ returning this value requires that `list.0.0.0.0.0.value` is borrowed for `'a`
 
 error[E0499]: cannot borrow `list.0.0.0.0.0.next` as mutable more than once at a time
-  --> $DIR/assignment-to-differing-field.rs:40:26
+  --> $DIR/assignment-to-differing-field.rs:43:26
    |
 LL | fn assignment_through_projection_chain<'a, T>(
    |                                        -- lifetime `'a` defined here
diff --git a/tests/ui/nll/polonius/assignment-to-differing-field.polonius.stderr b/tests/ui/nll/polonius/assignment-to-differing-field.polonius.stderr
new file mode 100644
index 00000000000..cf5594dbd07
--- /dev/null
+++ b/tests/ui/nll/polonius/assignment-to-differing-field.polonius.stderr
@@ -0,0 +1,51 @@
+error[E0499]: cannot borrow `list.0.value` as mutable more than once at a time
+  --> $DIR/assignment-to-differing-field.rs:23:21
+   |
+LL | fn assignment_to_field_projection<'a, T>(
+   |                                   -- lifetime `'a` defined here
+...
+LL |         result.push(&mut (list.0).value);
+   |                     ^^^^^^^^^^^^^^^^^^^ `list.0.value` was mutably borrowed here in the previous iteration of the loop
+...
+LL |             return result;
+   |                    ------ returning this value requires that `list.0.value` is borrowed for `'a`
+
+error[E0499]: cannot borrow `list.0.next` as mutable more than once at a time
+  --> $DIR/assignment-to-differing-field.rs:26:26
+   |
+LL | fn assignment_to_field_projection<'a, T>(
+   |                                   -- lifetime `'a` defined here
+...
+LL |         if let Some(n) = (list.0).next.as_mut() {
+   |                          ^^^^^^^^^^^^^ `list.0.next` was mutably borrowed here in the previous iteration of the loop
+LL |
+LL |             list.1 = n;
+   |             ---------- assignment requires that `list.0.next` is borrowed for `'a`
+
+error[E0499]: cannot borrow `list.0.0.0.0.0.value` as mutable more than once at a time
+  --> $DIR/assignment-to-differing-field.rs:40:21
+   |
+LL | fn assignment_through_projection_chain<'a, T>(
+   |                                        -- lifetime `'a` defined here
+...
+LL |         result.push(&mut ((((list.0).0).0).0).0.value);
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `list.0.0.0.0.0.value` was mutably borrowed here in the previous iteration of the loop
+...
+LL |             return result;
+   |                    ------ returning this value requires that `list.0.0.0.0.0.value` is borrowed for `'a`
+
+error[E0499]: cannot borrow `list.0.0.0.0.0.next` as mutable more than once at a time
+  --> $DIR/assignment-to-differing-field.rs:43:26
+   |
+LL | fn assignment_through_projection_chain<'a, T>(
+   |                                        -- lifetime `'a` defined here
+...
+LL |         if let Some(n) = ((((list.0).0).0).0).0.next.as_mut() {
+   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `list.0.0.0.0.0.next` was mutably borrowed here in the previous iteration of the loop
+LL |
+LL |             *((((list.0).0).0).0).1 = n;
+   |             --------------------------- assignment requires that `list.0.0.0.0.0.next` is borrowed for `'a`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0499`.
diff --git a/tests/ui/nll/polonius/assignment-to-differing-field.rs b/tests/ui/nll/polonius/assignment-to-differing-field.rs
index fb6c9569525..9701cd2bb5e 100644
--- a/tests/ui/nll/polonius/assignment-to-differing-field.rs
+++ b/tests/ui/nll/polonius/assignment-to-differing-field.rs
@@ -4,7 +4,10 @@
 // that we do not kill too many borrows. Assignments to the `.1`
 // field projections should leave the borrows on `.0` intact.
 
-//@ compile-flags: -Z polonius
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius legacy
+//@ [polonius] compile-flags: -Z polonius=next
+//@ [legacy] compile-flags: -Z polonius=legacy
 
 struct List<T> {
     value: T,
diff --git a/tests/ui/nll/polonius/call-kills-loans.rs b/tests/ui/nll/polonius/call-kills-loans.rs
index c02293c9a78..0657c42f48c 100644
--- a/tests/ui/nll/polonius/call-kills-loans.rs
+++ b/tests/ui/nll/polonius/call-kills-loans.rs
@@ -4,8 +4,11 @@
 // by NLL but was incorrectly rejected by Polonius because of these
 // missing `killed` facts.
 
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius_next polonius
 //@ check-pass
-//@ compile-flags: -Z polonius
+//@ [polonius_next] compile-flags: -Z polonius=next
+//@ [polonius] compile-flags: -Z polonius
 
 struct Thing;
 
diff --git a/tests/ui/nll/polonius/issue-46589.rs b/tests/ui/nll/polonius/issue-46589.rs
deleted file mode 100644
index af791f7e24d..00000000000
--- a/tests/ui/nll/polonius/issue-46589.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-// This test is a copy of `ui/nll/issue-46589.rs` which fails in NLL but succeeds in Polonius.
-// As we can't have a test here which conditionally passes depending on a test
-// revision/compile-flags. We ensure here that it passes in Polonius mode.
-
-//@ check-pass
-//@ compile-flags: -Z polonius
-
-struct Foo;
-
-impl Foo {
-    fn get_self(&mut self) -> Option<&mut Self> {
-        Some(self)
-    }
-
-    fn new_self(&mut self) -> &mut Self {
-        self
-    }
-
-    fn trigger_bug(&mut self) {
-        let other = &mut (&mut *self);
-
-        *other = match (*other).get_self() {
-            Some(s) => s,
-            None => (*other).new_self()
-        };
-
-        let c = other;
-    }
-}
-
-fn main() {}
diff --git a/tests/ui/nll/polonius/location-insensitive-scopes-liveness.rs b/tests/ui/nll/polonius/location-insensitive-scopes-liveness.rs
index cb56c8f6deb..677b7aa1df8 100644
--- a/tests/ui/nll/polonius/location-insensitive-scopes-liveness.rs
+++ b/tests/ui/nll/polonius/location-insensitive-scopes-liveness.rs
@@ -5,9 +5,11 @@
 // than `liveness::trace`, on some specific CFGs shapes: a variable was dead during tracing but its
 // regions were marked live later, and live loans were not recomputed at this point.
 
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius_next polonius
 //@ check-pass
-//@ revisions: nll polonius
-//@ [polonius] compile-flags: -Zpolonius=next
+//@ [polonius_next] compile-flags: -Z polonius=next
+//@ [polonius] compile-flags: -Z polonius
 
 // minimized from wavefc-cli-3.0.0
 fn repro1() {
diff --git a/tests/ui/nll/polonius/polonius-smoke-test.stderr b/tests/ui/nll/polonius/polonius-smoke-test.legacy.stderr
index a8a8267290d..1268f6167f8 100644
--- a/tests/ui/nll/polonius/polonius-smoke-test.stderr
+++ b/tests/ui/nll/polonius/polonius-smoke-test.legacy.stderr
@@ -1,11 +1,11 @@
 error[E0515]: cannot return reference to local variable `x`
-  --> $DIR/polonius-smoke-test.rs:6:5
+  --> $DIR/polonius-smoke-test.rs:10:5
    |
 LL |     &x
    |     ^^ returns a reference to data owned by the current function
 
 error[E0503]: cannot use `x` because it was mutably borrowed
-  --> $DIR/polonius-smoke-test.rs:12:13
+  --> $DIR/polonius-smoke-test.rs:16:13
    |
 LL |     let y = &mut x;
    |             ------ `x` is borrowed here
@@ -15,7 +15,7 @@ LL |     let w = y;
    |             - borrow later used here
 
 error[E0505]: cannot move out of `x` because it is borrowed
-  --> $DIR/polonius-smoke-test.rs:18:13
+  --> $DIR/polonius-smoke-test.rs:22:13
    |
 LL | pub fn use_while_mut_fr(x: &mut i32) -> &mut i32 {
    |                         -  - let's call the lifetime of this reference `'1`
@@ -35,7 +35,7 @@ LL +     let y = &mut x.clone();
    |
 
 error[E0505]: cannot move out of `s` because it is borrowed
-  --> $DIR/polonius-smoke-test.rs:42:5
+  --> $DIR/polonius-smoke-test.rs:46:5
    |
 LL |     let s = &mut 1;
    |         - binding `s` declared here
diff --git a/tests/ui/nll/polonius/polonius-smoke-test.polonius.stderr b/tests/ui/nll/polonius/polonius-smoke-test.polonius.stderr
new file mode 100644
index 00000000000..1268f6167f8
--- /dev/null
+++ b/tests/ui/nll/polonius/polonius-smoke-test.polonius.stderr
@@ -0,0 +1,59 @@
+error[E0515]: cannot return reference to local variable `x`
+  --> $DIR/polonius-smoke-test.rs:10:5
+   |
+LL |     &x
+   |     ^^ returns a reference to data owned by the current function
+
+error[E0503]: cannot use `x` because it was mutably borrowed
+  --> $DIR/polonius-smoke-test.rs:16:13
+   |
+LL |     let y = &mut x;
+   |             ------ `x` is borrowed here
+LL |     let z = x;
+   |             ^ use of borrowed `x`
+LL |     let w = y;
+   |             - borrow later used here
+
+error[E0505]: cannot move out of `x` because it is borrowed
+  --> $DIR/polonius-smoke-test.rs:22:13
+   |
+LL | pub fn use_while_mut_fr(x: &mut i32) -> &mut i32 {
+   |                         -  - let's call the lifetime of this reference `'1`
+   |                         |
+   |                         binding `x` declared here
+LL |     let y = &mut *x;
+   |             ------- borrow of `*x` occurs here
+LL |     let z = x;
+   |             ^ move out of `x` occurs here
+LL |     y
+   |     - returning this value requires that `*x` is borrowed for `'1`
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL -     let y = &mut *x;
+LL +     let y = &mut x.clone();
+   |
+
+error[E0505]: cannot move out of `s` because it is borrowed
+  --> $DIR/polonius-smoke-test.rs:46:5
+   |
+LL |     let s = &mut 1;
+   |         - binding `s` declared here
+LL |     let r = &mut *s;
+   |             ------- borrow of `*s` occurs here
+LL |     let tmp = foo(&r);
+LL |     s;
+   |     ^ move out of `s` occurs here
+LL |     tmp;
+   |     --- borrow later used here
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL -     let r = &mut *s;
+LL +     let r = &mut s.clone();
+   |
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0503, E0505, E0515.
+For more information about an error, try `rustc --explain E0503`.
diff --git a/tests/ui/nll/polonius/polonius-smoke-test.rs b/tests/ui/nll/polonius/polonius-smoke-test.rs
index ea5cdb263f5..7fbb3f9b47c 100644
--- a/tests/ui/nll/polonius/polonius-smoke-test.rs
+++ b/tests/ui/nll/polonius/polonius-smoke-test.rs
@@ -1,5 +1,9 @@
-// Check that Polonius borrow check works for simple cases.
-//@ compile-flags: -Z polonius
+// Check that Polonius works for simple cases.
+
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius legacy
+//@ [polonius] compile-flags: -Z polonius=next
+//@ [legacy] compile-flags: -Z polonius=legacy
 
 pub fn return_ref_to_local() -> &'static i32 {
     let x = 0;
diff --git a/tests/ui/nll/polonius/storagedead-kills-loans.rs b/tests/ui/nll/polonius/storagedead-kills-loans.rs
index 89cf919bb48..75a37e6ece5 100644
--- a/tests/ui/nll/polonius/storagedead-kills-loans.rs
+++ b/tests/ui/nll/polonius/storagedead-kills-loans.rs
@@ -3,8 +3,11 @@
 // is correctly accepted by NLL but was incorrectly rejected by
 // Polonius because of these missing `killed` facts.
 
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius_next polonius
 //@ check-pass
-//@ compile-flags: -Z polonius
+//@ [polonius_next] compile-flags: -Z polonius=next
+//@ [polonius] compile-flags: -Z polonius
 
 use std::{io, mem};
 use std::io::Read;
diff --git a/tests/ui/nll/polonius/subset-relations.stderr b/tests/ui/nll/polonius/subset-relations.legacy.stderr
index 9deca6449a8..10d42ca58d9 100644
--- a/tests/ui/nll/polonius/subset-relations.stderr
+++ b/tests/ui/nll/polonius/subset-relations.legacy.stderr
@@ -1,5 +1,5 @@
 error: lifetime may not live long enough
-  --> $DIR/subset-relations.rs:10:5
+  --> $DIR/subset-relations.rs:13:5
    |
 LL | fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
    |                   --  -- lifetime `'b` defined here
diff --git a/tests/ui/nll/polonius/subset-relations.polonius.stderr b/tests/ui/nll/polonius/subset-relations.polonius.stderr
new file mode 100644
index 00000000000..10d42ca58d9
--- /dev/null
+++ b/tests/ui/nll/polonius/subset-relations.polonius.stderr
@@ -0,0 +1,14 @@
+error: lifetime may not live long enough
+  --> $DIR/subset-relations.rs:13:5
+   |
+LL | fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
+   |                   --  -- lifetime `'b` defined here
+   |                   |
+   |                   lifetime `'a` defined here
+LL |     y
+   |     ^ function was supposed to return data with lifetime `'a` but it is returning data with lifetime `'b`
+   |
+   = help: consider adding the following bound: `'b: 'a`
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/nll/polonius/subset-relations.rs b/tests/ui/nll/polonius/subset-relations.rs
index 3c1af1983cf..d47e4e05533 100644
--- a/tests/ui/nll/polonius/subset-relations.rs
+++ b/tests/ui/nll/polonius/subset-relations.rs
@@ -3,7 +3,10 @@
 // two free regions outlive each other, without any evidence that this
 // relation holds.
 
-//@ compile-flags: -Z polonius
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius legacy
+//@ [polonius] compile-flags: -Z polonius=next
+//@ [legacy] compile-flags: -Z polonius=legacy
 
 // returning `y` requires that `'b: 'a`, but it's not known to be true
 fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
@@ -22,7 +25,7 @@ fn implied_bounds_subset<'a, 'b>(x: &'a &'b mut u32) -> &'a u32 {
 
 // `'b: 'a` is declared, and `'a: 'c` is known via implied bounds:
 // `'b: 'c` is therefore known to hold transitively
-fn transitively_valid_subset<'a, 'b: 'a, 'c>(x: &'c &'a u32, y: &'b u32) -> &'c u32  {
+fn transitively_valid_subset<'a, 'b: 'a, 'c>(x: &'c &'a u32, y: &'b u32) -> &'c u32 {
     y
 }
 
diff --git a/tests/ui/panics/issue-47429-short-backtraces.rs b/tests/ui/panics/issue-47429-short-backtraces.rs
index 4a73ebe8712..378ade67bfd 100644
--- a/tests/ui/panics/issue-47429-short-backtraces.rs
+++ b/tests/ui/panics/issue-47429-short-backtraces.rs
@@ -17,8 +17,6 @@
 //@ ignore-msvc see #62897 and `backtrace-debuginfo.rs` test
 //@ ignore-android FIXME #17520
 //@ ignore-openbsd no support for libbacktrace without filename
-//@ ignore-wasm no panic support
-//@ ignore-emscripten no panic support
 //@ ignore-fuchsia Backtraces not symbolized
 //@ needs-subprocess
 
diff --git a/tests/ui/panics/issue-47429-short-backtraces.run.stderr b/tests/ui/panics/issue-47429-short-backtraces.run.stderr
index c6e2d13fb5d..32dc6592271 100644
--- a/tests/ui/panics/issue-47429-short-backtraces.run.stderr
+++ b/tests/ui/panics/issue-47429-short-backtraces.run.stderr
@@ -1,5 +1,5 @@
 
-thread 'main' panicked at $DIR/issue-47429-short-backtraces.rs:26:5:
+thread 'main' panicked at $DIR/issue-47429-short-backtraces.rs:24:5:
 explicit panic
 stack backtrace:
    0: std::panicking::begin_panic
diff --git a/tests/ui/panics/runtime-switch.rs b/tests/ui/panics/runtime-switch.rs
index 9f0be8c7ddf..7d5b4169340 100644
--- a/tests/ui/panics/runtime-switch.rs
+++ b/tests/ui/panics/runtime-switch.rs
@@ -18,7 +18,6 @@
 //@ ignore-android FIXME #17520
 //@ ignore-openbsd no support for libbacktrace without filename
 //@ ignore-wasm no backtrace support
-//@ ignore-emscripten no panic support
 //@ ignore-fuchsia Backtrace not symbolized
 //@ needs-subprocess
 
diff --git a/tests/ui/panics/runtime-switch.run.stderr b/tests/ui/panics/runtime-switch.run.stderr
index 458a0ee534a..70ed127af86 100644
--- a/tests/ui/panics/runtime-switch.run.stderr
+++ b/tests/ui/panics/runtime-switch.run.stderr
@@ -1,5 +1,5 @@
 
-thread 'main' panicked at $DIR/runtime-switch.rs:29:5:
+thread 'main' panicked at $DIR/runtime-switch.rs:28:5:
 explicit panic
 stack backtrace:
    0: std::panicking::begin_panic
diff --git a/tests/ui/panics/short-ice-remove-middle-frames-2.rs b/tests/ui/panics/short-ice-remove-middle-frames-2.rs
index 48f60b14170..660530f0ead 100644
--- a/tests/ui/panics/short-ice-remove-middle-frames-2.rs
+++ b/tests/ui/panics/short-ice-remove-middle-frames-2.rs
@@ -5,7 +5,6 @@
 //@ needs-unwind
 //@ ignore-android FIXME #17520
 //@ ignore-openbsd no support for libbacktrace without filename
-//@ ignore-emscripten no panic
 //@ ignore-sgx Backtraces not symbolized
 //@ ignore-fuchsia Backtraces not symbolized
 //@ ignore-msvc the `__rust_{begin,end}_short_backtrace` symbols aren't reliable.
diff --git a/tests/ui/panics/short-ice-remove-middle-frames-2.run.stderr b/tests/ui/panics/short-ice-remove-middle-frames-2.run.stderr
index 1fddcca6951..664d51e185d 100644
--- a/tests/ui/panics/short-ice-remove-middle-frames-2.run.stderr
+++ b/tests/ui/panics/short-ice-remove-middle-frames-2.run.stderr
@@ -1,5 +1,5 @@
 
-thread 'main' panicked at $DIR/short-ice-remove-middle-frames-2.rs:63:5:
+thread 'main' panicked at $DIR/short-ice-remove-middle-frames-2.rs:62:5:
 debug!!!
 stack backtrace:
    0: std::panicking::begin_panic
diff --git a/tests/ui/panics/short-ice-remove-middle-frames.rs b/tests/ui/panics/short-ice-remove-middle-frames.rs
index 216c5127799..41fb6e9950e 100644
--- a/tests/ui/panics/short-ice-remove-middle-frames.rs
+++ b/tests/ui/panics/short-ice-remove-middle-frames.rs
@@ -5,7 +5,6 @@
 //@ needs-unwind
 //@ ignore-android FIXME #17520
 //@ ignore-openbsd no support for libbacktrace without filename
-//@ ignore-emscripten no panic
 //@ ignore-sgx Backtraces not symbolized
 //@ ignore-fuchsia Backtraces not symbolized
 //@ ignore-msvc the `__rust_{begin,end}_short_backtrace` symbols aren't reliable.
diff --git a/tests/ui/panics/short-ice-remove-middle-frames.run.stderr b/tests/ui/panics/short-ice-remove-middle-frames.run.stderr
index 630b09d8d1e..e966462331f 100644
--- a/tests/ui/panics/short-ice-remove-middle-frames.run.stderr
+++ b/tests/ui/panics/short-ice-remove-middle-frames.run.stderr
@@ -1,5 +1,5 @@
 
-thread 'main' panicked at $DIR/short-ice-remove-middle-frames.rs:59:5:
+thread 'main' panicked at $DIR/short-ice-remove-middle-frames.rs:58:5:
 debug!!!
 stack backtrace:
    0: std::panicking::begin_panic
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.rs b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.rs
index dab01179c0b..215e64979f7 100644
--- a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.rs
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.rs
@@ -1,3 +1,4 @@
+//! Ensure ABI-incompatible features cannot be enabled via `#[target_feature]`.
 //@ compile-flags: --target=riscv32e-unknown-none-elf --crate-type=lib
 //@ needs-llvm-components: riscv
 #![feature(no_core, lang_items, riscv_target_feature)]
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.stderr b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.stderr
index 9df56d86729..bfe767e5ffb 100644
--- a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.stderr
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.stderr
@@ -1,5 +1,5 @@
 error: target feature `d` cannot be enabled with `#[target_feature]`: this feature is incompatible with the target ABI
-  --> $DIR/forbidden-hardfloat-target-feature-attribute.rs:9:18
+  --> $DIR/forbidden-hardfloat-target-feature-attribute.rs:10:18
    |
 LL | #[target_feature(enable = "d")]
    |                  ^^^^^^^^^^^^
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-cfg.rs b/tests/ui/target-feature/forbidden-hardfloat-target-feature-cfg.rs
deleted file mode 100644
index 8755791c1c0..00000000000
--- a/tests/ui/target-feature/forbidden-hardfloat-target-feature-cfg.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
-//@ needs-llvm-components: x86
-//@ check-pass
-#![feature(no_core, lang_items)]
-#![no_core]
-#![allow(unexpected_cfgs)]
-
-#[lang = "sized"]
-pub trait Sized {}
-
-// The compile_error macro does not exist, so if the `cfg` evaluates to `true` this
-// complains about the missing macro rather than showing the error... but that's good enough.
-#[cfg(not(target_feature = "x87"))]
-compile_error!("the x87 feature *should* be exposed in `cfg`");
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-implied.rs b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-implied.rs
index 3d09217327a..81f138b175f 100644
--- a/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-implied.rs
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-implied.rs
@@ -1,8 +1,11 @@
+//! Ensure that if disabling a target feature implies disabling an ABI-required target feature,
+//! we complain.
 //@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
 //@ needs-llvm-components: x86
 //@ compile-flags: -Ctarget-feature=-sse
 // For now this is just a warning.
 //@ build-pass
+//@error-pattern: must be enabled to ensure that the ABI
 #![feature(no_core, lang_items)]
 #![no_core]
 
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-neon.rs b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-neon.rs
index 95c366bb3f5..7242bcc85bf 100644
--- a/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-neon.rs
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-neon.rs
@@ -3,6 +3,7 @@
 //@ compile-flags: -Ctarget-feature=-neon
 // For now this is just a warning.
 //@ build-pass
+//@error-pattern: must be enabled to ensure that the ABI
 #![feature(no_core, lang_items)]
 #![no_core]
 
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable.rs b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable.rs
index fd8023664da..7eebcf05dc0 100644
--- a/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable.rs
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable.rs
@@ -1,8 +1,10 @@
+//! Ensure ABI-required features cannot be disabled via `-Ctarget-feature`.
 //@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
 //@ needs-llvm-components: x86
 //@ compile-flags: -Ctarget-feature=-x87
 // For now this is just a warning.
 //@ build-pass
+//@error-pattern: must be enabled to ensure that the ABI
 #![feature(no_core, lang_items)]
 #![no_core]
 
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag.rs b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag.rs
new file mode 100644
index 00000000000..f277a309cd6
--- /dev/null
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag.rs
@@ -0,0 +1,12 @@
+//! Ensure ABI-incompatible features cannot be enabled via `-Ctarget-feature`.
+//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
+//@ needs-llvm-components: x86
+//@ compile-flags: -Ctarget-feature=+soft-float
+// For now this is just a warning.
+//@ build-pass
+//@error-pattern: must be disabled to ensure that the ABI
+#![feature(no_core, lang_items, riscv_target_feature)]
+#![no_core]
+
+#[lang = "sized"]
+pub trait Sized {}
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag.stderr b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag.stderr
new file mode 100644
index 00000000000..e49672f33b9
--- /dev/null
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-flag.stderr
@@ -0,0 +1,11 @@
+warning: target feature `soft-float` must be disabled to ensure that the ABI of the current target can be implemented correctly
+   |
+   = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>
+
+warning: unstable feature specified for `-Ctarget-feature`: `soft-float`
+   |
+   = note: this feature is not stably supported; its behavior can change in the future
+
+warning: 2 warnings emitted
+
diff --git a/tests/ui/target-feature/forbidden-target-feature-attribute.rs b/tests/ui/target-feature/forbidden-target-feature-attribute.rs
index 2ba5f2215c7..6bb6f8aaffb 100644
--- a/tests/ui/target-feature/forbidden-target-feature-attribute.rs
+++ b/tests/ui/target-feature/forbidden-target-feature-attribute.rs
@@ -1,11 +1,12 @@
-//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
-//@ needs-llvm-components: x86
+//! Ensure "forbidden" target features cannot be enabled via `#[target_feature]`.
+//@ compile-flags: --target=riscv32e-unknown-none-elf --crate-type=lib
+//@ needs-llvm-components: riscv
 #![feature(no_core, lang_items)]
 #![no_core]
 
 #[lang = "sized"]
 pub trait Sized {}
 
-#[target_feature(enable = "soft-float")]
+#[target_feature(enable = "forced-atomics")]
 //~^ERROR: cannot be enabled with
 pub unsafe fn my_fun() {}
diff --git a/tests/ui/target-feature/forbidden-target-feature-attribute.stderr b/tests/ui/target-feature/forbidden-target-feature-attribute.stderr
index f3d54cc19d3..f8ea0c0e793 100644
--- a/tests/ui/target-feature/forbidden-target-feature-attribute.stderr
+++ b/tests/ui/target-feature/forbidden-target-feature-attribute.stderr
@@ -1,8 +1,8 @@
-error: target feature `soft-float` cannot be enabled with `#[target_feature]`: unsound because it changes float ABI
-  --> $DIR/forbidden-target-feature-attribute.rs:9:18
+error: target feature `forced-atomics` cannot be enabled with `#[target_feature]`: unsound because it changes the ABI of atomic operations
+  --> $DIR/forbidden-target-feature-attribute.rs:10:18
    |
-LL | #[target_feature(enable = "soft-float")]
-   |                  ^^^^^^^^^^^^^^^^^^^^^
+LL | #[target_feature(enable = "forced-atomics")]
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/target-feature/forbidden-target-feature-cfg.rs b/tests/ui/target-feature/forbidden-target-feature-cfg.rs
index 1f001e9f8ff..e848ffde018 100644
--- a/tests/ui/target-feature/forbidden-target-feature-cfg.rs
+++ b/tests/ui/target-feature/forbidden-target-feature-cfg.rs
@@ -1,5 +1,6 @@
-//@ compile-flags: --target=x86_64-unknown-none --crate-type=lib
-//@ needs-llvm-components: x86
+//! Ensure "forbidden" target features are not exposed via `cfg`.
+//@ compile-flags: --target=riscv32e-unknown-none-elf --crate-type=lib
+//@ needs-llvm-components: riscv
 //@ check-pass
 #![feature(no_core, lang_items)]
 #![no_core]
@@ -10,5 +11,5 @@ pub trait Sized {}
 
 // The compile_error macro does not exist, so if the `cfg` evaluates to `true` this
 // complains about the missing macro rather than showing the error... but that's good enough.
-#[cfg(target_feature = "soft-float")]
-compile_error!("the soft-float feature should not be exposed in `cfg`");
+#[cfg(target_feature = "forced-atomics")]
+compile_error!("the forced-atomics feature should not be exposed in `cfg`");
diff --git a/tests/ui/target-feature/forbidden-target-feature-flag-disable.rs b/tests/ui/target-feature/forbidden-target-feature-flag-disable.rs
index b09c53bd46a..cf85c521228 100644
--- a/tests/ui/target-feature/forbidden-target-feature-flag-disable.rs
+++ b/tests/ui/target-feature/forbidden-target-feature-flag-disable.rs
@@ -1,8 +1,10 @@
-//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
-//@ needs-llvm-components: x86
-//@ compile-flags: -Ctarget-feature=-soft-float
+//! Ensure "forbidden" target features cannot be disabled via `-Ctarget-feature`.
+//@ compile-flags: --target=riscv32e-unknown-none-elf --crate-type=lib
+//@ needs-llvm-components: riscv
+//@ compile-flags: -Ctarget-feature=-forced-atomics
 // For now this is just a warning.
 //@ build-pass
+//@error-pattern: unsound because it changes the ABI
 #![feature(no_core, lang_items)]
 #![no_core]
 
diff --git a/tests/ui/target-feature/forbidden-target-feature-flag-disable.stderr b/tests/ui/target-feature/forbidden-target-feature-flag-disable.stderr
index 797cd4be5c2..171ed0de6aa 100644
--- a/tests/ui/target-feature/forbidden-target-feature-flag-disable.stderr
+++ b/tests/ui/target-feature/forbidden-target-feature-flag-disable.stderr
@@ -1,4 +1,4 @@
-warning: target feature `soft-float` cannot be disabled with `-Ctarget-feature`: unsound because it changes float ABI
+warning: target feature `forced-atomics` cannot be disabled with `-Ctarget-feature`: unsound because it changes the ABI of atomic operations
    |
    = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>
diff --git a/tests/ui/target-feature/forbidden-target-feature-flag.rs b/tests/ui/target-feature/forbidden-target-feature-flag.rs
index 0f688fde7f4..245841eb039 100644
--- a/tests/ui/target-feature/forbidden-target-feature-flag.rs
+++ b/tests/ui/target-feature/forbidden-target-feature-flag.rs
@@ -1,8 +1,10 @@
-//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
-//@ needs-llvm-components: x86
-//@ compile-flags: -Ctarget-feature=+soft-float
+//! Ensure "forbidden" target features cannot be enabled via `-Ctarget-feature`.
+//@ compile-flags: --target=riscv32e-unknown-none-elf --crate-type=lib
+//@ needs-llvm-components: riscv
+//@ compile-flags: -Ctarget-feature=+forced-atomics
 // For now this is just a warning.
 //@ build-pass
+//@error-pattern: unsound because it changes the ABI
 #![feature(no_core, lang_items)]
 #![no_core]
 
diff --git a/tests/ui/target-feature/forbidden-target-feature-flag.stderr b/tests/ui/target-feature/forbidden-target-feature-flag.stderr
index 075666fbf66..f8490f066d1 100644
--- a/tests/ui/target-feature/forbidden-target-feature-flag.stderr
+++ b/tests/ui/target-feature/forbidden-target-feature-flag.stderr
@@ -1,4 +1,4 @@
-warning: target feature `soft-float` cannot be enabled with `-Ctarget-feature`: unsound because it changes float ABI
+warning: target feature `forced-atomics` cannot be enabled with `-Ctarget-feature`: unsound because it changes the ABI of atomic operations
    |
    = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>
diff --git a/tests/ui/target_modifiers/auxiliary/default_reg_struct_return.rs b/tests/ui/target_modifiers/auxiliary/default_reg_struct_return.rs
new file mode 100644
index 00000000000..355e7c56e94
--- /dev/null
+++ b/tests/ui/target_modifiers/auxiliary/default_reg_struct_return.rs
@@ -0,0 +1,20 @@
+//@ compile-flags: --target i686-unknown-linux-gnu -Cpanic=abort
+// Auxiliary build problems with aarch64-apple:
+// Shared library linking cc seems to convert "-m32" flag into -arch armv4t
+// Auxiliary build problems with i686-mingw: linker `cc` not found
+//@ only-x86
+//@ ignore-windows
+//@ ignore-apple
+//@ needs-llvm-components: x86
+#![crate_type = "rlib"]
+#![no_core]
+#![feature(no_core, lang_items, repr_simd)]
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+pub fn somefun() {}
+
+pub struct S;
diff --git a/tests/ui/target_modifiers/auxiliary/wrong_regparm.rs b/tests/ui/target_modifiers/auxiliary/wrong_regparm.rs
new file mode 100644
index 00000000000..2e16f1ee747
--- /dev/null
+++ b/tests/ui/target_modifiers/auxiliary/wrong_regparm.rs
@@ -0,0 +1,20 @@
+//@ compile-flags: --target i686-unknown-linux-gnu -Zregparm=2 -Cpanic=abort
+// Auxiliary build problems with aarch64-apple:
+// Shared library linking cc seems to convert "-m32" flag into -arch armv4t
+// Auxiliary build problems with i686-mingw: linker `cc` not found
+//@ only-x86
+//@ ignore-windows
+//@ ignore-apple
+//@ needs-llvm-components: x86
+#![crate_type = "rlib"]
+#![no_core]
+#![feature(no_core, lang_items, repr_simd)]
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+pub fn somefun() {}
+
+pub struct S;
diff --git a/tests/ui/target_modifiers/auxiliary/wrong_regparm_and_ret.rs b/tests/ui/target_modifiers/auxiliary/wrong_regparm_and_ret.rs
new file mode 100644
index 00000000000..39c6be9d589
--- /dev/null
+++ b/tests/ui/target_modifiers/auxiliary/wrong_regparm_and_ret.rs
@@ -0,0 +1,20 @@
+//@ compile-flags: --target i686-unknown-linux-gnu -Zregparm=2 -Zreg-struct-return=true -Cpanic=abort
+// Auxiliary build problems with aarch64-apple:
+// Shared library linking cc seems to convert "-m32" flag into -arch armv4t
+// Auxiliary build problems with i686-mingw: linker `cc` not found
+//@ only-x86
+//@ ignore-windows
+//@ ignore-apple
+//@ needs-llvm-components: x86
+#![crate_type = "rlib"]
+#![no_core]
+#![feature(no_core, lang_items, repr_simd)]
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+pub fn somefun() {}
+
+pub struct S;
diff --git a/tests/ui/target_modifiers/defaults_check.error.stderr b/tests/ui/target_modifiers/defaults_check.error.stderr
new file mode 100644
index 00000000000..c545dd71069
--- /dev/null
+++ b/tests/ui/target_modifiers/defaults_check.error.stderr
@@ -0,0 +1,13 @@
+error: mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `defaults_check`
+  --> $DIR/defaults_check.rs:20:1
+   |
+LL | #![crate_type = "rlib"]
+   | ^
+   |
+   = help: the `-Zreg-struct-return` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
+   = note: `-Zreg-struct-return=true` in this crate is incompatible with `-Zreg-struct-return=` in dependency `default_reg_struct_return`
+   = help: set `-Zreg-struct-return=` in this crate or `-Zreg-struct-return=true` in `default_reg_struct_return`
+   = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=reg-struct-return` to silence this error
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/target_modifiers/defaults_check.rs b/tests/ui/target_modifiers/defaults_check.rs
new file mode 100644
index 00000000000..b8f4848d3a4
--- /dev/null
+++ b/tests/ui/target_modifiers/defaults_check.rs
@@ -0,0 +1,27 @@
+// Tests that default unspecified target modifier value in dependency crate is ok linked
+// with the same value, explicitly specified
+//@ aux-crate:default_reg_struct_return=default_reg_struct_return.rs
+//@ compile-flags: --target i686-unknown-linux-gnu -Cpanic=abort
+//@ revisions:error ok ok_explicit
+//@[ok] compile-flags:
+//@[ok_explicit] compile-flags: -Zreg-struct-return=false
+//@[error] compile-flags: -Zreg-struct-return=true
+
+// Auxiliary build problems with aarch64-apple:
+// Shared library linking cc seems to convert "-m32" flag into -arch armv4t
+// Auxiliary build problems with i686-mingw: linker `cc` not found
+//@ only-x86
+//@ ignore-windows
+//@ ignore-apple
+//@ needs-llvm-components: x86
+//@[ok] build-pass
+//@[ok_explicit] build-pass
+
+#![crate_type = "rlib"]
+//[error]~^ ERROR mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `defaults_check`
+#![no_core]
+#![feature(no_core, lang_items, repr_simd)]
+
+fn foo() {
+    default_reg_struct_return::somefun();
+}
diff --git a/tests/ui/target_modifiers/incompatible_regparm.allow_no_value.stderr b/tests/ui/target_modifiers/incompatible_regparm.allow_no_value.stderr
new file mode 100644
index 00000000000..8597332825b
--- /dev/null
+++ b/tests/ui/target_modifiers/incompatible_regparm.allow_no_value.stderr
@@ -0,0 +1,2 @@
+error: codegen option `unsafe-allow-abi-mismatch` requires a comma-separated list of strings (C unsafe-allow-abi-mismatch=<value>)
+
diff --git a/tests/ui/target_modifiers/incompatible_regparm.error_generated.stderr b/tests/ui/target_modifiers/incompatible_regparm.error_generated.stderr
new file mode 100644
index 00000000000..692fc7a4e3f
--- /dev/null
+++ b/tests/ui/target_modifiers/incompatible_regparm.error_generated.stderr
@@ -0,0 +1,13 @@
+error: mixing `-Zregparm` will cause an ABI mismatch in crate `incompatible_regparm`
+  --> $DIR/incompatible_regparm.rs:16:1
+   |
+LL | #![crate_type = "rlib"]
+   | ^
+   |
+   = help: the `-Zregparm` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
+   = note: `-Zregparm=1` in this crate is incompatible with `-Zregparm=2` in dependency `wrong_regparm`
+   = help: set `-Zregparm=2` in this crate or `-Zregparm=1` in `wrong_regparm`
+   = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=regparm` to silence this error
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/target_modifiers/incompatible_regparm.rs b/tests/ui/target_modifiers/incompatible_regparm.rs
new file mode 100644
index 00000000000..e866c5aa891
--- /dev/null
+++ b/tests/ui/target_modifiers/incompatible_regparm.rs
@@ -0,0 +1,23 @@
+//@ aux-crate:wrong_regparm=wrong_regparm.rs
+//@ compile-flags: --target i686-unknown-linux-gnu -Zregparm=1 -Cpanic=abort
+// Auxiliary build problems with aarch64-apple:
+// Shared library linking cc seems to convert "-m32" flag into -arch armv4t
+// Auxiliary build problems with i686-mingw: linker `cc` not found
+//@ only-x86
+//@ ignore-windows
+//@ ignore-apple
+//@ needs-llvm-components: x86
+//@ revisions:error_generated allow_regparm_mismatch allow_no_value
+
+//@[allow_regparm_mismatch] compile-flags: -Cunsafe-allow-abi-mismatch=regparm
+//@[allow_regparm_mismatch] build-pass
+//@[allow_no_value] compile-flags: -Cunsafe-allow-abi-mismatch
+
+#![crate_type = "rlib"]
+//[error_generated]~^ ERROR mixing `-Zregparm` will cause an ABI mismatch in crate `incompatible_regparm`
+#![no_core]
+#![feature(no_core, lang_items, repr_simd)]
+
+fn foo() {
+    wrong_regparm::somefun();
+}
diff --git a/tests/ui/target_modifiers/two_flags.rs b/tests/ui/target_modifiers/two_flags.rs
new file mode 100644
index 00000000000..ca17117a267
--- /dev/null
+++ b/tests/ui/target_modifiers/two_flags.rs
@@ -0,0 +1,23 @@
+//@ aux-crate:wrong_regparm_and_ret=wrong_regparm_and_ret.rs
+//@ compile-flags: --target i686-unknown-linux-gnu -Cpanic=abort
+// Auxiliary build problems with aarch64-apple:
+// Shared library linking cc seems to convert "-m32" flag into -arch armv4t
+// Auxiliary build problems with i686-mingw: linker `cc` not found
+//@ only-x86
+//@ ignore-windows
+//@ ignore-apple
+//@ needs-llvm-components: x86
+//@ revisions:two_allowed unknown_allowed
+
+//@[two_allowed] compile-flags: -Cunsafe-allow-abi-mismatch=regparm,reg-struct-return
+//@[two_allowed] build-pass
+//@[unknown_allowed] compile-flags: -Cunsafe-allow-abi-mismatch=unknown_flag -Zregparm=2 -Zreg-struct-return=true
+
+#![crate_type = "rlib"]
+//[unknown_allowed]~^ ERROR unknown target modifier `unknown_flag`, requested by `-Cunsafe-allow-abi-mismatch=unknown_flag`
+#![no_core]
+#![feature(no_core, lang_items, repr_simd)]
+
+fn foo() {
+    wrong_regparm_and_ret::somefun();
+}
diff --git a/tests/ui/target_modifiers/two_flags.unknown_allowed.stderr b/tests/ui/target_modifiers/two_flags.unknown_allowed.stderr
new file mode 100644
index 00000000000..c8040c6e389
--- /dev/null
+++ b/tests/ui/target_modifiers/two_flags.unknown_allowed.stderr
@@ -0,0 +1,8 @@
+error: unknown target modifier `unknown_flag`, requested by `-Cunsafe-allow-abi-mismatch=unknown_flag`
+  --> $DIR/two_flags.rs:16:1
+   |
+LL | #![crate_type = "rlib"]
+   | ^
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/test-attrs/test-panic-abort-disabled.rs b/tests/ui/test-attrs/test-panic-abort-disabled.rs
index 05dd9395c2b..e83be65f925 100644
--- a/tests/ui/test-attrs/test-panic-abort-disabled.rs
+++ b/tests/ui/test-attrs/test-panic-abort-disabled.rs
@@ -4,8 +4,6 @@
 //@ run-flags: --test-threads=1
 
 //@ needs-unwind
-//@ ignore-wasm no panic support
-//@ ignore-emscripten no panic support
 //@ needs-subprocess
 
 #![cfg(test)]
diff --git a/tests/ui/test-attrs/test-panic-abort-nocapture.rs b/tests/ui/test-attrs/test-panic-abort-nocapture.rs
index f7e15dbdbc3..6a1025ea087 100644
--- a/tests/ui/test-attrs/test-panic-abort-nocapture.rs
+++ b/tests/ui/test-attrs/test-panic-abort-nocapture.rs
@@ -7,8 +7,6 @@
 //@ normalize-stdout: "finished in \d+\.\d+s" -> "finished in $$TIME"
 
 //@ ignore-android #120567
-//@ ignore-wasm no panic support
-//@ ignore-emscripten no panic support
 //@ needs-subprocess
 
 #![cfg(test)]
diff --git a/tests/ui/test-attrs/test-panic-abort-nocapture.run.stderr b/tests/ui/test-attrs/test-panic-abort-nocapture.run.stderr
index 25681171170..b9f267838b1 100644
--- a/tests/ui/test-attrs/test-panic-abort-nocapture.run.stderr
+++ b/tests/ui/test-attrs/test-panic-abort-nocapture.run.stderr
@@ -1,11 +1,11 @@
 
-thread 'main' panicked at $DIR/test-panic-abort-nocapture.rs:34:5:
+thread 'main' panicked at $DIR/test-panic-abort-nocapture.rs:32:5:
 assertion `left == right` failed
   left: 2
  right: 4
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
-thread 'main' panicked at $DIR/test-panic-abort-nocapture.rs:28:5:
+thread 'main' panicked at $DIR/test-panic-abort-nocapture.rs:26:5:
 assertion `left == right` failed
   left: 2
  right: 4
diff --git a/tests/ui/test-attrs/test-panic-abort.rs b/tests/ui/test-attrs/test-panic-abort.rs
index 951cf54346b..6c9b641fb6f 100644
--- a/tests/ui/test-attrs/test-panic-abort.rs
+++ b/tests/ui/test-attrs/test-panic-abort.rs
@@ -7,8 +7,6 @@
 //@ normalize-stdout: "finished in \d+\.\d+s" -> "finished in $$TIME"
 
 //@ ignore-android #120567
-//@ ignore-wasm no panic support
-//@ ignore-emscripten no panic support
 //@ needs-subprocess
 
 #![cfg(test)]
diff --git a/tests/ui/test-attrs/test-panic-abort.run.stdout b/tests/ui/test-attrs/test-panic-abort.run.stdout
index 844808e8637..0faa7f0dfce 100644
--- a/tests/ui/test-attrs/test-panic-abort.run.stdout
+++ b/tests/ui/test-attrs/test-panic-abort.run.stdout
@@ -18,7 +18,7 @@ testing123
 ---- it_fails stderr ----
 testing321
 
-thread 'main' panicked at $DIR/test-panic-abort.rs:39:5:
+thread 'main' panicked at $DIR/test-panic-abort.rs:37:5:
 assertion `left == right` failed
   left: 2
  right: 5