diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 2e6c1dceef98a..7a5eb28940e4c 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -1544,8 +1544,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
             Rvalue::Use(operand)
             | Rvalue::Repeat(operand, _)
             | Rvalue::UnaryOp(_ /*un_op*/, operand)
-            | Rvalue::Cast(_ /*cast_kind*/, operand, _ /*ty*/)
-            | Rvalue::ShallowInitBox(operand, _ /*ty*/) => {
+            | Rvalue::Cast(_ /*cast_kind*/, operand, _ /*ty*/) => {
                 self.consume_operand(location, (operand, span), state)
             }
 
diff --git a/compiler/rustc_borrowck/src/polonius/legacy/loan_invalidations.rs b/compiler/rustc_borrowck/src/polonius/legacy/loan_invalidations.rs
index 99567da92ffe7..439aa1a91e068 100644
--- a/compiler/rustc_borrowck/src/polonius/legacy/loan_invalidations.rs
+++ b/compiler/rustc_borrowck/src/polonius/legacy/loan_invalidations.rs
@@ -297,8 +297,9 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {
             Rvalue::Use(operand)
             | Rvalue::Repeat(operand, _)
             | Rvalue::UnaryOp(_ /*un_op*/, operand)
-            | Rvalue::Cast(_ /*cast_kind*/, operand, _ /*ty*/)
-            | Rvalue::ShallowInitBox(operand, _ /*ty*/) => self.consume_operand(location, operand),
+            | Rvalue::Cast(_ /*cast_kind*/, operand, _ /*ty*/) => {
+                self.consume_operand(location, operand)
+            }
 
             &Rvalue::Discriminant(place) => {
                 self.access_place(
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 7d34d7c88e629..2935559147b7e 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -1004,17 +1004,6 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 }
             }
 
-            Rvalue::ShallowInitBox(_operand, ty) => {
-                let trait_ref =
-                    ty::TraitRef::new(tcx, tcx.require_lang_item(LangItem::Sized, span), [*ty]);
-
-                self.prove_trait_ref(
-                    trait_ref,
-                    location.to_locations(),
-                    ConstraintCategory::SizedBound,
-                );
-            }
-
             Rvalue::Cast(cast_kind, op, ty) => {
                 match *cast_kind {
                     CastKind::PointerCoercion(
@@ -2231,7 +2220,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             | Rvalue::Ref(..)
             | Rvalue::RawPtr(..)
             | Rvalue::Cast(..)
-            | Rvalue::ShallowInitBox(..)
             | Rvalue::BinaryOp(..)
             | Rvalue::CopyForDeref(..)
             | Rvalue::UnaryOp(..)
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs
index 1a916c8768243..e4865ece63b6c 100644
--- a/compiler/rustc_codegen_cranelift/src/base.rs
+++ b/compiler/rustc_codegen_cranelift/src/base.rs
@@ -902,7 +902,6 @@ fn codegen_stmt<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, cur_block: Block, stmt:
                     lval.write_cvalue_transmute(fx, operand);
                 }
                 Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in codegen"),
-                Rvalue::ShallowInitBox(..) => bug!("`ShallowInitBox` in codegen"),
             }
         }
         StatementKind::StorageLive(_)
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index ca8c8dd06ba61..2cb96c4ec0f59 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -710,7 +710,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 OperandRef { val: operand.val, layout, move_annotation: None }
             }
             mir::Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in codegen"),
-            mir::Rvalue::ShallowInitBox(..) => bug!("`ShallowInitBox` in codegen"),
         }
     }
 
diff --git a/compiler/rustc_const_eval/src/check_consts/check.rs b/compiler/rustc_const_eval/src/check_consts/check.rs
index 564f67e5b1e46..9c9a921bd62d5 100644
--- a/compiler/rustc_const_eval/src/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/check_consts/check.rs
@@ -646,8 +646,6 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
 
             Rvalue::Cast(_, _, _) => {}
 
-            Rvalue::ShallowInitBox(_, _) => {}
-
             Rvalue::UnaryOp(op, operand) => {
                 let ty = operand.ty(self.body, self.tcx);
                 match op {
diff --git a/compiler/rustc_const_eval/src/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/check_consts/qualifs.rs
index 462254f064cf3..1fbd0cd234057 100644
--- a/compiler/rustc_const_eval/src/check_consts/qualifs.rs
+++ b/compiler/rustc_const_eval/src/check_consts/qualifs.rs
@@ -237,8 +237,7 @@ where
         Rvalue::Use(operand)
         | Rvalue::Repeat(operand, _)
         | Rvalue::UnaryOp(_, operand)
-        | Rvalue::Cast(_, operand, _)
-        | Rvalue::ShallowInitBox(operand, _) => in_operand::<Q, _>(cx, in_local, operand),
+        | Rvalue::Cast(_, operand, _) => in_operand::<Q, _>(cx, in_local, operand),
 
         Rvalue::BinaryOp(_, box (lhs, rhs)) => {
             in_operand::<Q, _>(cx, in_local, lhs) || in_operand::<Q, _>(cx, in_local, rhs)
diff --git a/compiler/rustc_const_eval/src/check_consts/resolver.rs b/compiler/rustc_const_eval/src/check_consts/resolver.rs
index d4cc21996aea8..044b8b091b8de 100644
--- a/compiler/rustc_const_eval/src/check_consts/resolver.rs
+++ b/compiler/rustc_const_eval/src/check_consts/resolver.rs
@@ -192,7 +192,6 @@ where
             }
 
             mir::Rvalue::Cast(..)
-            | mir::Rvalue::ShallowInitBox(..)
             | mir::Rvalue::Use(..)
             | mir::Rvalue::CopyForDeref(..)
             | mir::Rvalue::ThreadLocalRef(..)
diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index 57ad670c3f567..3b4f7ed3261ab 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -236,7 +236,7 @@ impl<'tcx> CompileTimeInterpCx<'tcx> {
         if self.tcx.is_lang_item(def_id, LangItem::PanicDisplay)
             || self.tcx.is_lang_item(def_id, LangItem::BeginPanic)
         {
-            let args = self.copy_fn_args(args);
+            let args = Self::copy_fn_args(args);
             // &str or &&str
             assert!(args.len() == 1);
 
diff --git a/compiler/rustc_const_eval/src/interpret/call.rs b/compiler/rustc_const_eval/src/interpret/call.rs
index 1ee2647d5bf78..9220fde474e4e 100644
--- a/compiler/rustc_const_eval/src/interpret/call.rs
+++ b/compiler/rustc_const_eval/src/interpret/call.rs
@@ -19,8 +19,8 @@ use tracing::{info, instrument, trace};
 
 use super::{
     CtfeProvenance, FnVal, ImmTy, InterpCx, InterpResult, MPlaceTy, Machine, OpTy, PlaceTy,
-    Projectable, Provenance, ReturnAction, ReturnContinuation, Scalar, StackPopInfo, interp_ok,
-    throw_ub, throw_ub_custom,
+    Projectable, Provenance, ReturnAction, ReturnContinuation, Scalar, interp_ok, throw_ub,
+    throw_ub_custom,
 };
 use crate::enter_trace_span;
 use crate::interpret::EnteredTraceSpan;
@@ -43,25 +43,22 @@ impl<'tcx, Prov: Provenance> FnArg<'tcx, Prov> {
             FnArg::InPlace(mplace) => &mplace.layout,
         }
     }
-}
 
-impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     /// Make a copy of the given fn_arg. Any `InPlace` are degenerated to copies, no protection of the
     /// original memory occurs.
-    pub fn copy_fn_arg(&self, arg: &FnArg<'tcx, M::Provenance>) -> OpTy<'tcx, M::Provenance> {
-        match arg {
+    pub fn copy_fn_arg(&self) -> OpTy<'tcx, Prov> {
+        match self {
             FnArg::Copy(op) => op.clone(),
             FnArg::InPlace(mplace) => mplace.clone().into(),
         }
     }
+}
 
+impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     /// Make a copy of the given fn_args. Any `InPlace` are degenerated to copies, no protection of the
     /// original memory occurs.
-    pub fn copy_fn_args(
-        &self,
-        args: &[FnArg<'tcx, M::Provenance>],
-    ) -> Vec<OpTy<'tcx, M::Provenance>> {
-        args.iter().map(|fn_arg| self.copy_fn_arg(fn_arg)).collect()
+    pub fn copy_fn_args(args: &[FnArg<'tcx, M::Provenance>]) -> Vec<OpTy<'tcx, M::Provenance>> {
+        args.iter().map(|fn_arg| fn_arg.copy_fn_arg()).collect()
     }
 
     /// Helper function for argument untupling.
@@ -319,7 +316,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         // We work with a copy of the argument for now; if this is in-place argument passing, we
         // will later protect the source it comes from. This means the callee cannot observe if we
         // did in-place of by-copy argument passing, except for pointer equality tests.
-        let caller_arg_copy = self.copy_fn_arg(caller_arg);
+        let caller_arg_copy = caller_arg.copy_fn_arg();
         if !already_live {
             let local = callee_arg.as_local().unwrap();
             let meta = caller_arg_copy.meta();
@@ -616,7 +613,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 if let Some(fallback) = M::call_intrinsic(
                     self,
                     instance,
-                    &self.copy_fn_args(args),
+                    &Self::copy_fn_args(args),
                     destination,
                     target,
                     unwind,
@@ -703,7 +700,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 // An `InPlace` does nothing here, we keep the original receiver intact. We can't
                 // really pass the argument in-place anyway, and we are constructing a new
                 // `Immediate` receiver.
-                let mut receiver = self.copy_fn_arg(&args[0]);
+                let mut receiver = args[0].copy_fn_arg();
                 let receiver_place = loop {
                     match receiver.layout.ty.kind() {
                         ty::Ref(..) | ty::RawPtr(..) => {
@@ -824,41 +821,50 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         with_caller_location: bool,
     ) -> InterpResult<'tcx> {
         trace!("init_fn_tail_call: {:#?}", fn_val);
-
         // This is the "canonical" implementation of tails calls,
         // a pop of the current stack frame, followed by a normal call
         // which pushes a new stack frame, with the return address from
         // the popped stack frame.
         //
-        // Note that we are using `pop_stack_frame_raw` and not `return_from_current_stack_frame`,
-        // as the latter "executes" the goto to the return block, but we don't want to,
+        // Note that we cannot use `return_from_current_stack_frame`,
+        // as that "executes" the goto to the return block, but we don't want to,
         // only the tail called function should return to the current return block.
-        let StackPopInfo { return_action, return_cont, return_place } =
-            self.pop_stack_frame_raw(false, |_this, _return_place| {
-                // This function's return value is just discarded, the tail-callee will fill in the return place instead.
-                interp_ok(())
-            })?;
 
-        assert_eq!(return_action, ReturnAction::Normal);
-
-        // Take the "stack pop cleanup" info, and use that to initiate the next call.
-        let ReturnContinuation::Goto { ret, unwind } = return_cont else {
-            bug!("can't tailcall as root");
+        // The arguments need to all be copied since the current stack frame will be removed
+        // before the callee even starts executing.
+        // FIXME(explicit_tail_calls,#144855): does this match what codegen does?
+        let args = args.iter().map(|fn_arg| FnArg::Copy(fn_arg.copy_fn_arg())).collect::<Vec<_>>();
+        // Remove the frame from the stack.
+        let frame = self.pop_stack_frame_raw()?;
+        // Remember where this frame would have returned to.
+        let ReturnContinuation::Goto { ret, unwind } = frame.return_cont() else {
+            bug!("can't tailcall as root of the stack");
         };
-
+        // There's no return value to deal with! Instead, we forward the old return place
+        // to the new function.
         // FIXME(explicit_tail_calls):
         //   we should check if both caller&callee can/n't unwind,
         //   see <https://github.com/rust-lang/rust/pull/113128#issuecomment-1614979803>
 
+        // Now push the new stack frame.
         self.init_fn_call(
             fn_val,
             (caller_abi, caller_fn_abi),
-            args,
+            &*args,
             with_caller_location,
-            &return_place,
+            frame.return_place(),
             ret,
             unwind,
-        )
+        )?;
+
+        // Finally, clear the local variables. Has to be done after pushing to support
+        // non-scalar arguments.
+        // FIXME(explicit_tail_calls,#144855): revisit this once codegen supports indirect
+        // arguments, to ensure the semantics are compatible.
+        let return_action = self.cleanup_stack_frame(/* unwinding */ false, frame)?;
+        assert_eq!(return_action, ReturnAction::Normal);
+
+        interp_ok(())
     }
 
     pub(super) fn init_drop_in_place_call(
@@ -953,14 +959,18 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         // local's value out.
         let return_op =
             self.local_to_op(mir::RETURN_PLACE, None).expect("return place should always be live");
-        // Do the actual pop + copy.
-        let stack_pop_info = self.pop_stack_frame_raw(unwinding, |this, return_place| {
-            this.copy_op_allow_transmute(&return_op, return_place)?;
-            trace!("return value: {:?}", this.dump_place(return_place));
-            interp_ok(())
-        })?;
-
-        match stack_pop_info.return_action {
+        // Remove the frame from the stack.
+        let frame = self.pop_stack_frame_raw()?;
+        // Copy the return value and remember the return continuation.
+        if !unwinding {
+            self.copy_op_allow_transmute(&return_op, frame.return_place())?;
+            trace!("return value: {:?}", self.dump_place(frame.return_place()));
+        }
+        let return_cont = frame.return_cont();
+        // Finish popping the stack frame.
+        let return_action = self.cleanup_stack_frame(unwinding, frame)?;
+        // Jump to the next block.
+        match return_action {
             ReturnAction::Normal => {}
             ReturnAction::NoJump => {
                 // The hook already did everything.
@@ -978,7 +988,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         // Normal return, figure out where to jump.
         if unwinding {
             // Follow the unwind edge.
-            match stack_pop_info.return_cont {
+            match return_cont {
                 ReturnContinuation::Goto { unwind, .. } => {
                     // This must be the very last thing that happens, since it can in fact push a new stack frame.
                     self.unwind_to_block(unwind)
@@ -989,7 +999,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             }
         } else {
             // Follow the normal return edge.
-            match stack_pop_info.return_cont {
+            match return_cont {
                 ReturnContinuation::Goto { ret, .. } => self.return_to_block(ret),
                 ReturnContinuation::Stop { .. } => {
                     assert!(
diff --git a/compiler/rustc_const_eval/src/interpret/mod.rs b/compiler/rustc_const_eval/src/interpret/mod.rs
index 2f365ec77b33e..c8ffc0ed208a7 100644
--- a/compiler/rustc_const_eval/src/interpret/mod.rs
+++ b/compiler/rustc_const_eval/src/interpret/mod.rs
@@ -36,7 +36,7 @@ pub use self::operand::{ImmTy, Immediate, OpTy};
 pub use self::place::{MPlaceTy, MemPlaceMeta, PlaceTy, Writeable};
 use self::place::{MemPlace, Place};
 pub use self::projection::{OffsetMode, Projectable};
-pub use self::stack::{Frame, FrameInfo, LocalState, ReturnContinuation, StackPopInfo};
+pub use self::stack::{Frame, FrameInfo, LocalState, ReturnContinuation};
 pub use self::util::EnteredTraceSpan;
 pub(crate) use self::util::create_static_alloc;
 pub use self::validity::{CtfeValidationMode, RangeSet, RefTracking};
diff --git a/compiler/rustc_const_eval/src/interpret/stack.rs b/compiler/rustc_const_eval/src/interpret/stack.rs
index 1b8af1c44277c..a55bea60cd6e2 100644
--- a/compiler/rustc_const_eval/src/interpret/stack.rs
+++ b/compiler/rustc_const_eval/src/interpret/stack.rs
@@ -81,7 +81,7 @@ pub struct Frame<'tcx, Prov: Provenance = CtfeProvenance, Extra = ()> {
     /// and its layout in the caller. This place is to be interpreted relative to the
     /// *caller's* stack frame. We use a `PlaceTy` instead of an `MPlaceTy` since this
     /// avoids having to move *all* return places into Miri's memory.
-    pub return_place: PlaceTy<'tcx, Prov>,
+    return_place: PlaceTy<'tcx, Prov>,
 
     /// The list of locals for this stack frame, stored in order as
     /// `[return_ptr, arguments..., variables..., temporaries...]`.
@@ -127,19 +127,6 @@ pub enum ReturnContinuation {
     Stop { cleanup: bool },
 }
 
-/// Return type of [`InterpCx::pop_stack_frame_raw`].
-pub struct StackPopInfo<'tcx, Prov: Provenance> {
-    /// Additional information about the action to be performed when returning from the popped
-    /// stack frame.
-    pub return_action: ReturnAction,
-
-    /// [`return_cont`](Frame::return_cont) of the popped stack frame.
-    pub return_cont: ReturnContinuation,
-
-    /// [`return_place`](Frame::return_place) of the popped stack frame.
-    pub return_place: PlaceTy<'tcx, Prov>,
-}
-
 /// State of a local variable including a memoized layout
 #[derive(Clone)]
 pub struct LocalState<'tcx, Prov: Provenance = CtfeProvenance> {
@@ -292,6 +279,14 @@ impl<'tcx, Prov: Provenance, Extra> Frame<'tcx, Prov, Extra> {
         self.instance
     }
 
+    pub fn return_place(&self) -> &PlaceTy<'tcx, Prov> {
+        &self.return_place
+    }
+
+    pub fn return_cont(&self) -> ReturnContinuation {
+        self.return_cont
+    }
+
     /// Return the `SourceInfo` of the current instruction.
     pub fn current_source_info(&self) -> Option<&mir::SourceInfo> {
         self.loc.left().map(|loc| self.body.source_info(loc))
@@ -417,35 +412,26 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         interp_ok(())
     }
 
-    /// Low-level helper that pops a stack frame from the stack and returns some information about
-    /// it.
-    ///
-    /// This also deallocates locals, if necessary.
-    /// `copy_ret_val` gets called after the frame has been taken from the stack but before the locals have been deallocated.
-    ///
-    /// [`M::before_stack_pop`] and [`M::after_stack_pop`] are called by this function
-    /// automatically.
-    ///
-    /// The high-level version of this is `return_from_current_stack_frame`.
-    ///
-    /// [`M::before_stack_pop`]: Machine::before_stack_pop
-    /// [`M::after_stack_pop`]: Machine::after_stack_pop
+    /// Low-level helper that pops a stack frame from the stack without any cleanup.
+    /// This invokes `before_stack_pop`.
+    /// After calling this function, you need to deal with the return value, and then
+    /// invoke `cleanup_stack_frame`.
     pub(super) fn pop_stack_frame_raw(
         &mut self,
-        unwinding: bool,
-        copy_ret_val: impl FnOnce(&mut Self, &PlaceTy<'tcx, M::Provenance>) -> InterpResult<'tcx>,
-    ) -> InterpResult<'tcx, StackPopInfo<'tcx, M::Provenance>> {
+    ) -> InterpResult<'tcx, Frame<'tcx, M::Provenance, M::FrameExtra>> {
         M::before_stack_pop(self)?;
         let frame =
             self.stack_mut().pop().expect("tried to pop a stack frame, but there were none");
+        interp_ok(frame)
+    }
 
-        // Copy return value (unless we are unwinding).
-        if !unwinding {
-            copy_ret_val(self, &frame.return_place)?;
-        }
-
+    /// Deallocate local variables in the stack frame, and invoke `after_stack_pop`.
+    pub(super) fn cleanup_stack_frame(
+        &mut self,
+        unwinding: bool,
+        frame: Frame<'tcx, M::Provenance, M::FrameExtra>,
+    ) -> InterpResult<'tcx, ReturnAction> {
         let return_cont = frame.return_cont;
-        let return_place = frame.return_place.clone();
 
         // Cleanup: deallocate locals.
         // Usually we want to clean up (deallocate locals), but in a few rare cases we don't.
@@ -455,7 +441,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             ReturnContinuation::Stop { cleanup, .. } => cleanup,
         };
 
-        let return_action = if cleanup {
+        if cleanup {
             for local in &frame.locals {
                 self.deallocate_local(local.value)?;
             }
@@ -466,13 +452,11 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             // Call the machine hook, which determines the next steps.
             let return_action = M::after_stack_pop(self, frame, unwinding)?;
             assert_ne!(return_action, ReturnAction::NoCleanup);
-            return_action
+            interp_ok(return_action)
         } else {
             // We also skip the machine hook when there's no cleanup. This not a real "pop" anyway.
-            ReturnAction::NoCleanup
-        };
-
-        interp_ok(StackPopInfo { return_action, return_cont, return_place })
+            interp_ok(ReturnAction::NoCleanup)
+        }
     }
 
     /// In the current stack frame, mark all locals as live that are not arguments and don't have
@@ -655,7 +639,7 @@ impl<'a, 'tcx: 'a, M: Machine<'tcx>> InterpCx<'tcx, M> {
             let (_idx, callee_abi) = callee_abis.next().unwrap();
             assert!(self.check_argument_compat(caller_abi, callee_abi)?);
             // FIXME: do we have to worry about in-place argument passing?
-            let op = self.copy_fn_arg(fn_arg);
+            let op = fn_arg.copy_fn_arg();
             let mplace = self.allocate(op.layout, MemoryKind::Stack)?;
             self.copy_op(&op, &mplace)?;
 
diff --git a/compiler/rustc_const_eval/src/interpret/step.rs b/compiler/rustc_const_eval/src/interpret/step.rs
index 4aa9030cfe61c..0dd17f109be31 100644
--- a/compiler/rustc_const_eval/src/interpret/step.rs
+++ b/compiler/rustc_const_eval/src/interpret/step.rs
@@ -249,12 +249,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 self.write_immediate(*val, &dest)?;
             }
 
-            ShallowInitBox(ref operand, _) => {
-                let src = self.eval_operand(operand, None)?;
-                let v = self.read_immediate(&src)?;
-                self.write_immediate(*v, &dest)?;
-            }
-
             Cast(cast_kind, ref operand, cast_ty) => {
                 let src = self.eval_operand(operand, None)?;
                 let cast_ty =
diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs
index 5d8ae42f5eccd..6fc8d5ef8f965 100644
--- a/compiler/rustc_const_eval/src/interpret/validity.rs
+++ b/compiler/rustc_const_eval/src/interpret/validity.rs
@@ -647,13 +647,8 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
                 }
             } else {
                 // This is not CTFE, so it's Miri with recursive checking.
-                // FIXME: we do *not* check behind boxes, since creating a new box first creates it uninitialized
-                // and then puts the value in there, so briefly we have a box with uninit contents.
-                // FIXME: should we also skip `UnsafeCell` behind shared references? Currently that is not
+                // FIXME: should we also `UnsafeCell` behind shared references? Currently that is not
                 // needed since validation reads bypass Stacked Borrows and data race checks.
-                if matches!(ptr_kind, PointerKind::Box) {
-                    return interp_ok(());
-                }
             }
             let path = &self.path;
             ref_tracking.track(place, || {
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 5efaea44b3b9d..476be94efd9e4 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -2,12 +2,11 @@ use std::any::Any;
 use std::default::Default;
 use std::iter;
 use std::path::Component::Prefix;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 use std::rc::Rc;
 use std::sync::Arc;
 
 use rustc_ast::attr::MarkedAttrs;
-use rustc_ast::token::MetaVarKind;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::visit::{AssocCtxt, Visitor};
 use rustc_ast::{self as ast, AttrVec, Attribute, HasAttrs, Item, NodeId, PatKind, Safety};
@@ -22,14 +21,14 @@ use rustc_hir::limit::Limit;
 use rustc_hir::{Stability, find_attr};
 use rustc_lint_defs::RegisteredTools;
 use rustc_parse::MACRO_ARGUMENTS;
-use rustc_parse::parser::{AllowConstBlockItems, ForceCollect, Parser};
+use rustc_parse::parser::Parser;
 use rustc_session::Session;
 use rustc_session::parse::ParseSess;
 use rustc_span::def_id::{CrateNum, DefId, LocalDefId};
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::{AstPass, ExpnData, ExpnKind, LocalExpnId, MacroKind};
 use rustc_span::source_map::SourceMap;
-use rustc_span::{DUMMY_SP, FileName, Ident, Span, Symbol, kw, sym};
+use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw};
 use smallvec::{SmallVec, smallvec};
 use thin_vec::ThinVec;
 
@@ -1421,80 +1420,3 @@ pub fn resolve_path(sess: &Session, path: impl Into<PathBuf>, span: Span) -> PRe
         }
     }
 }
-
-/// If this item looks like a specific enums from `rental`, emit a fatal error.
-/// See #73345 and #83125 for more details.
-/// FIXME(#73933): Remove this eventually.
-fn pretty_printing_compatibility_hack(item: &Item, psess: &ParseSess) {
-    if let ast::ItemKind::Enum(ident, _, enum_def) = &item.kind
-        && ident.name == sym::ProceduralMasqueradeDummyType
-        && let [variant] = &*enum_def.variants
-        && variant.ident.name == sym::Input
-        && let FileName::Real(real) = psess.source_map().span_to_filename(ident.span)
-        && let Some(c) = real
-            .local_path()
-            .unwrap_or(Path::new(""))
-            .components()
-            .flat_map(|c| c.as_os_str().to_str())
-            .find(|c| c.starts_with("rental") || c.starts_with("allsorts-rental"))
-    {
-        let crate_matches = if c.starts_with("allsorts-rental") {
-            true
-        } else {
-            let mut version = c.trim_start_matches("rental-").split('.');
-            version.next() == Some("0")
-                && version.next() == Some("5")
-                && version.next().and_then(|c| c.parse::<u32>().ok()).is_some_and(|v| v < 6)
-        };
-
-        if crate_matches {
-            psess.dcx().emit_fatal(errors::ProcMacroBackCompat {
-                crate_name: "rental".to_string(),
-                fixed_version: "0.5.6".to_string(),
-            });
-        }
-    }
-}
-
-pub(crate) fn ann_pretty_printing_compatibility_hack(ann: &Annotatable, psess: &ParseSess) {
-    let item = match ann {
-        Annotatable::Item(item) => item,
-        Annotatable::Stmt(stmt) => match &stmt.kind {
-            ast::StmtKind::Item(item) => item,
-            _ => return,
-        },
-        _ => return,
-    };
-    pretty_printing_compatibility_hack(item, psess)
-}
-
-pub(crate) fn stream_pretty_printing_compatibility_hack(
-    kind: MetaVarKind,
-    stream: &TokenStream,
-    psess: &ParseSess,
-) {
-    let item = match kind {
-        MetaVarKind::Item => {
-            let mut parser = Parser::new(psess, stream.clone(), None);
-            // No need to collect tokens for this simple check.
-            parser
-                .parse_item(ForceCollect::No, AllowConstBlockItems::No)
-                .expect("failed to reparse item")
-                .expect("an actual item")
-        }
-        MetaVarKind::Stmt => {
-            let mut parser = Parser::new(psess, stream.clone(), None);
-            // No need to collect tokens for this simple check.
-            let stmt = parser
-                .parse_stmt(ForceCollect::No)
-                .expect("failed to reparse")
-                .expect("an actual stmt");
-            match &stmt.kind {
-                ast::StmtKind::Item(item) => item.clone(),
-                _ => return,
-            }
-        }
-        _ => return,
-    };
-    pretty_printing_compatibility_hack(&item, psess)
-}
diff --git a/compiler/rustc_expand/src/errors.rs b/compiler/rustc_expand/src/errors.rs
index b6fcc13321ee7..c7b0e0d211a4a 100644
--- a/compiler/rustc_expand/src/errors.rs
+++ b/compiler/rustc_expand/src/errors.rs
@@ -446,18 +446,6 @@ pub(crate) struct GlobDelegationTraitlessQpath {
     pub span: Span,
 }
 
-// This used to be the `proc_macro_back_compat` lint (#83125). It was later
-// turned into a hard error.
-#[derive(Diagnostic)]
-#[diag("using an old version of `{$crate_name}`")]
-#[note(
-    "older versions of the `{$crate_name}` crate no longer compile; please update to `{$crate_name}` v{$fixed_version}, or switch to one of the `{$crate_name}` alternatives"
-)]
-pub(crate) struct ProcMacroBackCompat {
-    pub crate_name: String,
-    pub fixed_version: String,
-}
-
 pub(crate) use metavar_exprs::*;
 mod metavar_exprs {
     use super::*;
diff --git a/compiler/rustc_expand/src/proc_macro.rs b/compiler/rustc_expand/src/proc_macro.rs
index e678557008133..a892b21d76227 100644
--- a/compiler/rustc_expand/src/proc_macro.rs
+++ b/compiler/rustc_expand/src/proc_macro.rs
@@ -105,11 +105,6 @@ impl MultiItemModifier for DeriveProcMacro {
         // (e.g. `fn foo() { #[derive(Debug)] struct Bar; }`)
         let is_stmt = matches!(item, Annotatable::Stmt(..));
 
-        // We used to have an alternative behaviour for crates that needed it.
-        // We had a lint for a long time, but now we just emit a hard error.
-        // Eventually we might remove the special case hard error check
-        // altogether. See #73345.
-        crate::base::ann_pretty_printing_compatibility_hack(&item, &ecx.sess.psess);
         let input = item.to_tokens();
 
         let invoc_id = ecx.current_expansion.id;
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 947b8a6e3e5ee..1da14ce0155d3 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -103,8 +103,8 @@ impl ToInternal<token::LitKind> for LitKind {
     }
 }
 
-impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStream, Span, Symbol>> {
-    fn from_internal((stream, rustc): (TokenStream, &mut Rustc<'_, '_>)) -> Self {
+impl FromInternal<TokenStream> for Vec<TokenTree<TokenStream, Span, Symbol>> {
+    fn from_internal(stream: TokenStream) -> Self {
         use rustc_ast::token::*;
 
         // Estimate the capacity as `stream.len()` rounded up to the next power
@@ -115,22 +115,6 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
         while let Some(tree) = iter.next() {
             let (Token { kind, span }, joint) = match tree.clone() {
                 tokenstream::TokenTree::Delimited(span, _, mut delim, mut stream) => {
-                    // We used to have an alternative behaviour for crates that
-                    // needed it: a hack used to pass AST fragments to
-                    // attribute and derive macros as a single nonterminal
-                    // token instead of a token stream. Such token needs to be
-                    // "unwrapped" and not represented as a delimited group. We
-                    // had a lint for a long time, but now we just emit a hard
-                    // error. Eventually we might remove the special case hard
-                    // error check altogether. See #73345.
-                    if let Delimiter::Invisible(InvisibleOrigin::MetaVar(kind)) = delim {
-                        crate::base::stream_pretty_printing_compatibility_hack(
-                            kind,
-                            &stream,
-                            rustc.psess(),
-                        );
-                    }
-
                     // In `mk_delimited` we avoid nesting invisible delimited
                     // of the same `MetaVarKind`. Here we do the same but
                     // ignore the `MetaVarKind` because it is discarded when we
@@ -687,7 +671,7 @@ impl server::Server for Rustc<'_, '_> {
         &mut self,
         stream: Self::TokenStream,
     ) -> Vec<TokenTree<Self::TokenStream, Self::Span, Self::Symbol>> {
-        FromInternal::from_internal((stream, self))
+        FromInternal::from_internal(stream)
     }
 
     fn span_debug(&mut self, span: Self::Span) -> String {
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index 2c2dae0fef52e..db8f459ef0451 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -1208,7 +1208,7 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         rustc_intrinsic_const_stable_indirect, Normal,
         template!(Word), WarnFollowing, EncodeCrossCrate::No,  "this is an internal implementation detail",
     ),
-    gated!(
+    rustc_attr!(
         rustc_allow_const_fn_unstable, Normal,
         template!(Word, List: &["feat1, feat2, ..."]), DuplicatesOk, EncodeCrossCrate::No,
         "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index b810cd0db8cd1..51283caafe662 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -287,10 +287,6 @@ declare_features! (
     (internal, panic_runtime, "1.10.0", Some(32837)),
     /// Allows using pattern types.
     (internal, pattern_types, "1.79.0", Some(123646)),
-    /// Allows using `#[rustc_allow_const_fn_unstable]`.
-    /// This is an attribute on `const fn` for the same
-    /// purpose as `#[allow_internal_unstable]`.
-    (internal, rustc_allow_const_fn_unstable, "1.49.0", Some(69399)),
     /// Allows using compiler's own crates.
     (unstable, rustc_private, "1.0.0", Some(27812)),
     /// Allows using internal rustdoc features like `doc(keyword)`.
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 2e6e96b4d8a80..e5fe01781e96d 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -1237,10 +1237,6 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                 }
             }
 
-            ShallowInitBox(ref place, ref ty) => {
-                with_no_trimmed_paths!(write!(fmt, "ShallowInitBox({place:?}, {ty})"))
-            }
-
             WrapUnsafeBinder(ref op, ty) => {
                 with_no_trimmed_paths!(write!(fmt, "wrap_binder!({op:?}; {ty})"))
             }
diff --git a/compiler/rustc_middle/src/mir/statement.rs b/compiler/rustc_middle/src/mir/statement.rs
index b1cb89bd37135..48dcef298d66a 100644
--- a/compiler/rustc_middle/src/mir/statement.rs
+++ b/compiler/rustc_middle/src/mir/statement.rs
@@ -747,11 +747,6 @@ impl<'tcx> ConstOperand<'tcx> {
 ///////////////////////////////////////////////////////////////////////////
 // Rvalues
 
-pub enum RvalueInitializationState {
-    Shallow,
-    Deep,
-}
-
 impl<'tcx> Rvalue<'tcx> {
     /// Returns true if rvalue can be safely removed when the result is unused.
     #[inline]
@@ -786,7 +781,6 @@ impl<'tcx> Rvalue<'tcx> {
             | Rvalue::UnaryOp(_, _)
             | Rvalue::Discriminant(_)
             | Rvalue::Aggregate(_, _)
-            | Rvalue::ShallowInitBox(_, _)
             | Rvalue::WrapUnsafeBinder(_, _) => true,
         }
     }
@@ -833,21 +827,10 @@ impl<'tcx> Rvalue<'tcx> {
                 }
                 AggregateKind::RawPtr(ty, mutability) => Ty::new_ptr(tcx, ty, mutability),
             },
-            Rvalue::ShallowInitBox(_, ty) => Ty::new_box(tcx, ty),
             Rvalue::CopyForDeref(ref place) => place.ty(local_decls, tcx).ty,
             Rvalue::WrapUnsafeBinder(_, ty) => ty,
         }
     }
-
-    #[inline]
-    /// Returns `true` if this rvalue is deeply initialized (most rvalues) or
-    /// whether its only shallowly initialized (`Rvalue::Box`).
-    pub fn initialization_state(&self) -> RvalueInitializationState {
-        match *self {
-            Rvalue::ShallowInitBox(_, _) => RvalueInitializationState::Shallow,
-            _ => RvalueInitializationState::Deep,
-        }
-    }
 }
 
 impl BorrowKind {
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index 6ec874fb15f71..35f67460f51c0 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -1458,13 +1458,6 @@ pub enum Rvalue<'tcx> {
     /// coroutine lowering, `Coroutine` aggregate kinds are disallowed too.
     Aggregate(Box<AggregateKind<'tcx>>, IndexVec<FieldIdx, Operand<'tcx>>),
 
-    /// Transmutes a `*mut u8` into shallow-initialized `Box<T>`.
-    ///
-    /// This is different from a normal transmute because dataflow analysis will treat the box as
-    /// initialized but its content as uninitialized. Like other pointer casts, this in general
-    /// affects alias analysis.
-    ShallowInitBox(Operand<'tcx>, Ty<'tcx>),
-
     /// A CopyForDeref is equivalent to a read from a place at the
     /// codegen level, but is treated specially by drop elaboration. When such a read happens, it
     /// is guaranteed (via nature of the mir_opt `Derefer` in rustc_mir_transform/src/deref_separator)
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs
index 07a36aef43201..16a8743a6d67b 100644
--- a/compiler/rustc_middle/src/mir/visit.rs
+++ b/compiler/rustc_middle/src/mir/visit.rs
@@ -810,11 +810,6 @@ macro_rules! make_mir_visitor {
                         }
                     }
 
-                    Rvalue::ShallowInitBox(operand, ty) => {
-                        self.visit_operand(operand, location);
-                        self.visit_ty($(& $mutability)? *ty, TyContext::Location(location));
-                    }
-
                     Rvalue::WrapUnsafeBinder(op, ty) => {
                         self.visit_operand(op, location);
                         self.visit_ty($(& $mutability)? *ty, TyContext::Location(location));
diff --git a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
index 4b2c52ad7999d..d5548266aa017 100644
--- a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
@@ -86,7 +86,6 @@ where
 
             Rvalue::Cast(..)
             | Rvalue::Ref(_, BorrowKind::Fake(_), _)
-            | Rvalue::ShallowInitBox(..)
             | Rvalue::Use(..)
             | Rvalue::ThreadLocalRef(..)
             | Rvalue::Repeat(..)
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
index ced9bd735ba2b..224abf6901b33 100644
--- a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
+++ b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
@@ -391,15 +391,7 @@ impl<'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> MoveDataBuilder<'a, 'tcx, F> {
             }
             StatementKind::Assign(box (place, rval)) => {
                 self.create_move_path(*place);
-                if let RvalueInitializationState::Shallow = rval.initialization_state() {
-                    // Box starts out uninitialized - need to create a separate
-                    // move-path for the interior so it will be separate from
-                    // the exterior.
-                    self.create_move_path(self.tcx.mk_place_deref(*place));
-                    self.gather_init(place.as_ref(), InitKind::Shallow);
-                } else {
-                    self.gather_init(place.as_ref(), InitKind::Deep);
-                }
+                self.gather_init(place.as_ref(), InitKind::Deep);
                 self.gather_rvalue(rval);
             }
             StatementKind::FakeRead(box (_, place)) => {
@@ -435,7 +427,6 @@ impl<'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> MoveDataBuilder<'a, 'tcx, F> {
             Rvalue::Use(ref operand)
             | Rvalue::Repeat(ref operand, _)
             | Rvalue::Cast(_, ref operand, _)
-            | Rvalue::ShallowInitBox(ref operand, _)
             | Rvalue::UnaryOp(_, ref operand)
             | Rvalue::WrapUnsafeBinder(ref operand, _) => self.gather_operand(operand),
             Rvalue::BinaryOp(ref _binop, box (ref lhs, ref rhs)) => {
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
index 604f1da1a3abb..93da4f3a0a818 100644
--- a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
+++ b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
@@ -467,7 +467,6 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> {
             Rvalue::Discriminant(place) => state.get_discr(place.as_ref(), &self.map),
             Rvalue::Use(operand) => return self.handle_operand(operand, state),
             Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in runtime MIR"),
-            Rvalue::ShallowInitBox(..) => bug!("`ShallowInitBox` in runtime MIR"),
             Rvalue::Ref(..) | Rvalue::RawPtr(..) => {
                 // We don't track such places.
                 return ValueOrPlace::TOP;
diff --git a/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs b/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs
index 808be19cbd817..68c47ec4c1922 100644
--- a/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs
+++ b/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs
@@ -1,12 +1,8 @@
 //! This pass transforms derefs of Box into a deref of the pointer inside Box.
 //!
 //! Box is not actually a pointer so it is incorrect to dereference it directly.
-//!
-//! `ShallowInitBox` being a device for drop elaboration to understand deferred assignment to box
-//! contents, we do not need this any more on runtime MIR.
 
-use rustc_abi::{FieldIdx, VariantIdx};
-use rustc_index::{IndexVec, indexvec};
+use rustc_abi::FieldIdx;
 use rustc_middle::mir::visit::MutVisitor;
 use rustc_middle::mir::*;
 use rustc_middle::span_bug;
@@ -89,68 +85,6 @@ impl<'a, 'tcx> MutVisitor<'tcx> for ElaborateBoxDerefVisitor<'a, 'tcx> {
 
         self.super_place(place, context, location);
     }
-
-    fn visit_statement(&mut self, stmt: &mut Statement<'tcx>, location: Location) {
-        self.super_statement(stmt, location);
-
-        let tcx = self.tcx;
-        let source_info = stmt.source_info;
-
-        if let StatementKind::Assign(box (_, ref mut rvalue)) = stmt.kind
-            && let Rvalue::ShallowInitBox(ref mut mutptr_to_u8, pointee) = *rvalue
-            && let ty::Adt(box_adt, box_args) = Ty::new_box(tcx, pointee).kind()
-        {
-            let args = tcx.mk_args(&[pointee.into()]);
-            let (unique_ty, nonnull_ty, ptr_ty) =
-                build_ptr_tys(tcx, pointee, self.unique_def, self.nonnull_def);
-            let adt_kind = |def: ty::AdtDef<'tcx>, args| {
-                Box::new(AggregateKind::Adt(def.did(), VariantIdx::ZERO, args, None, None))
-            };
-            let zst = |ty| {
-                Operand::Constant(Box::new(ConstOperand {
-                    span: source_info.span,
-                    user_ty: None,
-                    const_: Const::zero_sized(ty),
-                }))
-            };
-
-            let constptr = self.patch.new_temp(ptr_ty, source_info.span);
-            self.patch.add_assign(
-                location,
-                constptr.into(),
-                Rvalue::Cast(CastKind::Transmute, mutptr_to_u8.clone(), ptr_ty),
-            );
-
-            let nonnull = self.patch.new_temp(nonnull_ty, source_info.span);
-            self.patch.add_assign(
-                location,
-                nonnull.into(),
-                Rvalue::Aggregate(
-                    adt_kind(self.nonnull_def, args),
-                    indexvec![Operand::Move(constptr.into())],
-                ),
-            );
-
-            let unique = self.patch.new_temp(unique_ty, source_info.span);
-            let phantomdata_ty =
-                self.unique_def.non_enum_variant().fields[FieldIdx::ONE].ty(tcx, args);
-            self.patch.add_assign(
-                location,
-                unique.into(),
-                Rvalue::Aggregate(
-                    adt_kind(self.unique_def, args),
-                    indexvec![Operand::Move(nonnull.into()), zst(phantomdata_ty)],
-                ),
-            );
-
-            let global_alloc_ty =
-                box_adt.non_enum_variant().fields[FieldIdx::ONE].ty(tcx, box_args);
-            *rvalue = Rvalue::Aggregate(
-                adt_kind(*box_adt, box_args),
-                indexvec![Operand::Move(unique.into()), zst(global_alloc_ty)],
-            );
-        }
-    }
 }
 
 pub(super) struct ElaborateBoxDerefs;
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs
index 6507a5194adda..4e38b9dd6534b 100644
--- a/compiler/rustc_mir_transform/src/gvn.rs
+++ b/compiler/rustc_mir_transform/src/gvn.rs
@@ -1069,7 +1069,7 @@ impl<'body, 'a, 'tcx> VnState<'body, 'a, 'tcx> {
 
             // Unsupported values.
             Rvalue::ThreadLocalRef(..) => return None,
-            Rvalue::CopyForDeref(_) | Rvalue::ShallowInitBox(..) => {
+            Rvalue::CopyForDeref(_) => {
                 bug!("forbidden in runtime MIR: {rvalue:?}")
             }
         };
diff --git a/compiler/rustc_mir_transform/src/known_panics_lint.rs b/compiler/rustc_mir_transform/src/known_panics_lint.rs
index caaf300a88d64..873f6a01ec360 100644
--- a/compiler/rustc_mir_transform/src/known_panics_lint.rs
+++ b/compiler/rustc_mir_transform/src/known_panics_lint.rs
@@ -443,7 +443,6 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             | Rvalue::CopyForDeref(..)
             | Rvalue::Repeat(..)
             | Rvalue::Cast(..)
-            | Rvalue::ShallowInitBox(..)
             | Rvalue::Discriminant(..)
             | Rvalue::WrapUnsafeBinder(..) => {}
         }
@@ -605,8 +604,6 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
 
             Ref(..) | RawPtr(..) => return None,
 
-            ShallowInitBox(..) => return None,
-
             Cast(ref kind, ref value, to) => match kind {
                 CastKind::IntToInt | CastKind::IntToFloat => {
                     let value = self.eval_operand(value)?;
diff --git a/compiler/rustc_mir_transform/src/lint.rs b/compiler/rustc_mir_transform/src/lint.rs
index 88297a4efef7e..b8b1b930bc418 100644
--- a/compiler/rustc_mir_transform/src/lint.rs
+++ b/compiler/rustc_mir_transform/src/lint.rs
@@ -85,7 +85,6 @@ impl<'a, 'tcx> Visitor<'tcx> for Lint<'a, 'tcx> {
                     | Rvalue::Repeat(..)
                     | Rvalue::Aggregate(..)
                     | Rvalue::Cast(..)
-                    | Rvalue::ShallowInitBox(..)
                     | Rvalue::WrapUnsafeBinder(..) => true,
                     Rvalue::ThreadLocalRef(..)
                     | Rvalue::UnaryOp(..)
diff --git a/compiler/rustc_mir_transform/src/pass_manager.rs b/compiler/rustc_mir_transform/src/pass_manager.rs
index e225c31881f83..a081364165438 100644
--- a/compiler/rustc_mir_transform/src/pass_manager.rs
+++ b/compiler/rustc_mir_transform/src/pass_manager.rs
@@ -1,5 +1,6 @@
 use std::cell::RefCell;
 use std::collections::hash_map::Entry;
+use std::sync::atomic::Ordering;
 
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_middle::mir::{Body, MirDumper, MirPhase, RuntimePhase};
@@ -285,6 +286,19 @@ fn run_passes_inner<'tcx>(
                 continue;
             };
 
+            if is_optimization_stage(body, phase_change, optimizations)
+                && let Some(limit) = &tcx.sess.opts.unstable_opts.mir_opt_bisect_limit
+            {
+                if limited_by_opt_bisect(
+                    tcx,
+                    tcx.def_path_debug_str(body.source.def_id()),
+                    *limit,
+                    *pass,
+                ) {
+                    continue;
+                }
+            }
+
             let dumper = if pass.is_mir_dump_enabled()
                 && let Some(dumper) = MirDumper::new(tcx, pass_name, body)
             {
@@ -356,3 +370,46 @@ pub(super) fn dump_mir_for_phase_change<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tc
         dumper.set_show_pass_num().set_disambiguator(&"after").dump_mir(body)
     }
 }
+
+fn is_optimization_stage(
+    body: &Body<'_>,
+    phase_change: Option<MirPhase>,
+    optimizations: Optimizations,
+) -> bool {
+    optimizations == Optimizations::Allowed
+        && body.phase == MirPhase::Runtime(RuntimePhase::PostCleanup)
+        && phase_change == Some(MirPhase::Runtime(RuntimePhase::Optimized))
+}
+
+fn limited_by_opt_bisect<'tcx, P>(
+    tcx: TyCtxt<'tcx>,
+    def_path: String,
+    limit: usize,
+    pass: &P,
+) -> bool
+where
+    P: MirPass<'tcx> + ?Sized,
+{
+    let current_opt_bisect_count =
+        tcx.sess.mir_opt_bisect_eval_count.fetch_add(1, Ordering::Relaxed);
+
+    let can_run = current_opt_bisect_count < limit;
+
+    if can_run {
+        eprintln!(
+            "BISECT: running pass ({}) {} on {}",
+            current_opt_bisect_count + 1,
+            pass.name(),
+            def_path
+        );
+    } else {
+        eprintln!(
+            "BISECT: NOT running pass ({}) {} on {}",
+            current_opt_bisect_count + 1,
+            pass.name(),
+            def_path
+        );
+    }
+
+    !can_run
+}
diff --git a/compiler/rustc_mir_transform/src/promote_consts.rs b/compiler/rustc_mir_transform/src/promote_consts.rs
index 3d1537b95efa9..fb880caf876e2 100644
--- a/compiler/rustc_mir_transform/src/promote_consts.rs
+++ b/compiler/rustc_mir_transform/src/promote_consts.rs
@@ -449,8 +449,6 @@ impl<'tcx> Validator<'_, 'tcx> {
                 self.validate_operand(operand)?;
             }
 
-            Rvalue::ShallowInitBox(_, _) => return Err(Unpromotable),
-
             Rvalue::UnaryOp(op, operand) => {
                 match op {
                     // These operations can never fail.
diff --git a/compiler/rustc_mir_transform/src/single_use_consts.rs b/compiler/rustc_mir_transform/src/single_use_consts.rs
index 02caa92ad3fc8..6d33736d64ecb 100644
--- a/compiler/rustc_mir_transform/src/single_use_consts.rs
+++ b/compiler/rustc_mir_transform/src/single_use_consts.rs
@@ -85,7 +85,7 @@ impl<'tcx> crate::MirPass<'tcx> for SingleUseConsts {
     }
 
     fn is_required(&self) -> bool {
-        true
+        false
     }
 }
 
diff --git a/compiler/rustc_mir_transform/src/validate.rs b/compiler/rustc_mir_transform/src/validate.rs
index 1afdb4639a0ce..78c161ebd58c9 100644
--- a/compiler/rustc_mir_transform/src/validate.rs
+++ b/compiler/rustc_mir_transform/src/validate.rs
@@ -1259,14 +1259,6 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     }
                 }
             }
-            Rvalue::ShallowInitBox(operand, _) => {
-                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
-                    self.fail(location, format!("ShallowInitBox after ElaborateBoxDerefs"))
-                }
-
-                let a = operand.ty(&self.body.local_decls, self.tcx);
-                check_kinds!(a, "Cannot shallow init type {:?}", ty::RawPtr(..));
-            }
             Rvalue::Cast(kind, operand, target_type) => {
                 let op_ty = operand.ty(self.body, self.tcx);
                 match kind {
diff --git a/compiler/rustc_public/src/mir/body.rs b/compiler/rustc_public/src/mir/body.rs
index e81b32ec9acf5..51757c5827221 100644
--- a/compiler/rustc_public/src/mir/body.rs
+++ b/compiler/rustc_public/src/mir/body.rs
@@ -567,13 +567,6 @@ pub enum Rvalue {
     /// [#74836]: https://github.com/rust-lang/rust/issues/74836
     Repeat(Operand, TyConst),
 
-    /// Transmutes a `*mut u8` into shallow-initialized `Box<T>`.
-    ///
-    /// This is different from a normal transmute because dataflow analysis will treat the box as
-    /// initialized but its content as uninitialized. Like other pointer casts, this in general
-    /// affects alias analysis.
-    ShallowInitBox(Operand, Ty),
-
     /// Creates a pointer/reference to the given thread local.
     ///
     /// The yielded type is a `*mut T` if the static is mutable, otherwise if the static is extern a
@@ -651,7 +644,6 @@ impl Rvalue {
                 }
                 AggregateKind::RawPtr(ty, mutability) => Ok(Ty::new_ptr(ty, mutability)),
             },
-            Rvalue::ShallowInitBox(_, ty) => Ok(Ty::new_box(*ty)),
             Rvalue::CopyForDeref(place) => place.ty(locals),
         }
     }
diff --git a/compiler/rustc_public/src/mir/pretty.rs b/compiler/rustc_public/src/mir/pretty.rs
index 5ba72965cb292..bf2655e9a789c 100644
--- a/compiler/rustc_public/src/mir/pretty.rs
+++ b/compiler/rustc_public/src/mir/pretty.rs
@@ -383,7 +383,6 @@ fn pretty_rvalue<W: Write>(writer: &mut W, rval: &Rvalue) -> io::Result<()> {
         Rvalue::Repeat(op, cnst) => {
             write!(writer, "[{}; {}]", pretty_operand(op), pretty_ty_const(cnst))
         }
-        Rvalue::ShallowInitBox(_, _) => Ok(()),
         Rvalue::ThreadLocalRef(item) => {
             write!(writer, "thread_local_ref{item:?}")
         }
diff --git a/compiler/rustc_public/src/mir/visit.rs b/compiler/rustc_public/src/mir/visit.rs
index 678205171ecf2..e1d9cf31036e2 100644
--- a/compiler/rustc_public/src/mir/visit.rs
+++ b/compiler/rustc_public/src/mir/visit.rs
@@ -277,10 +277,6 @@ macro_rules! make_mir_visitor {
                         self.visit_operand(op, location);
                         self.visit_ty_const(constant, location);
                     }
-                    Rvalue::ShallowInitBox(op, ty) => {
-                        self.visit_ty(ty, location);
-                        self.visit_operand(op, location)
-                    }
                     Rvalue::ThreadLocalRef(_) => {}
                     Rvalue::UnaryOp(_, op) | Rvalue::Use(op) => {
                         self.visit_operand(op, location);
diff --git a/compiler/rustc_public/src/unstable/convert/stable/mir.rs b/compiler/rustc_public/src/unstable/convert/stable/mir.rs
index a77808cfb275d..d25751c81f3f5 100644
--- a/compiler/rustc_public/src/unstable/convert/stable/mir.rs
+++ b/compiler/rustc_public/src/unstable/convert/stable/mir.rs
@@ -240,9 +240,6 @@ impl<'tcx> Stable<'tcx> for mir::Rvalue<'tcx> {
                 let operands = operands.iter().map(|op| op.stable(tables, cx)).collect();
                 crate::mir::Rvalue::Aggregate(agg_kind.stable(tables, cx), operands)
             }
-            ShallowInitBox(op, ty) => {
-                crate::mir::Rvalue::ShallowInitBox(op.stable(tables, cx), ty.stable(tables, cx))
-            }
             CopyForDeref(place) => crate::mir::Rvalue::CopyForDeref(place.stable(tables, cx)),
             WrapUnsafeBinder(..) => todo!("FIXME(unsafe_binders):"),
         }
diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs
index 4e7622d08462e..0991ba5a2de11 100644
--- a/compiler/rustc_resolve/src/imports.rs
+++ b/compiler/rustc_resolve/src/imports.rs
@@ -371,6 +371,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // - A glob decl is overwritten by its clone after setting ambiguity in it.
         //   FIXME: avoid this by removing `warn_ambiguity`, or by triggering glob re-fetch
         //   with the same decl in some way.
+        // - A glob decl is overwritten by a glob decl with larger visibility.
+        //   FIXME: avoid this by updating this visibility in place.
         // - A glob decl is overwritten by a glob decl re-fetching an
         //   overwritten decl from other module (the recursive case).
         // Here we are detecting all such re-fetches and overwrite old decls
@@ -384,7 +386,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             // FIXME: reenable the asserts when `warn_ambiguity` is removed (#149195).
             // assert_ne!(old_deep_decl, deep_decl);
             // assert!(old_deep_decl.is_glob_import());
-            assert!(!deep_decl.is_glob_import());
+            // FIXME: reenable the assert when visibility is updated in place.
+            // assert!(!deep_decl.is_glob_import());
             if old_glob_decl.ambiguity.get().is_some() && glob_decl.ambiguity.get().is_none() {
                 // Do not lose glob ambiguities when re-fetching the glob.
                 glob_decl.ambiguity.set_unchecked(old_glob_decl.ambiguity.get());
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index 94f8444db142d..5a6982b8c29d5 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -4060,25 +4060,32 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                             "instead, you are more likely to want"
                         };
                         let mut owned_sugg = lt.kind == MissingLifetimeKind::Ampersand;
+                        let mut sugg_is_str_to_string = false;
                         let mut sugg = vec![(lt.span, String::new())];
                         if let Some((kind, _span)) = self.diag_metadata.current_function
                             && let FnKind::Fn(_, _, ast::Fn { sig, .. }) = kind
-                            && let ast::FnRetTy::Ty(ty) = &sig.decl.output
                         {
                             let mut lt_finder =
                                 LifetimeFinder { lifetime: lt.span, found: None, seen: vec![] };
-                            lt_finder.visit_ty(&ty);
-
-                            if let [Ty { span, kind: TyKind::Ref(_, mut_ty), .. }] =
-                                &lt_finder.seen[..]
-                            {
-                                // We might have a situation like
-                                // fn g(mut x: impl Iterator<Item = &'_ ()>) -> Option<&'_ ()>
-                                // but `lt.span` only points at `'_`, so to suggest `-> Option<()>`
-                                // we need to find a more accurate span to end up with
-                                // fn g<'a>(mut x: impl Iterator<Item = &'_ ()>) -> Option<()>
-                                sugg = vec![(span.with_hi(mut_ty.ty.span.lo()), String::new())];
-                                owned_sugg = true;
+                            for param in &sig.decl.inputs {
+                                lt_finder.visit_ty(&param.ty);
+                            }
+                            if let ast::FnRetTy::Ty(ret_ty) = &sig.decl.output {
+                                lt_finder.visit_ty(ret_ty);
+                                let mut ret_lt_finder =
+                                    LifetimeFinder { lifetime: lt.span, found: None, seen: vec![] };
+                                ret_lt_finder.visit_ty(ret_ty);
+                                if let [Ty { span, kind: TyKind::Ref(_, mut_ty), .. }] =
+                                    &ret_lt_finder.seen[..]
+                                {
+                                    // We might have a situation like
+                                    // fn g(mut x: impl Iterator<Item = &'_ ()>) -> Option<&'_ ()>
+                                    // but `lt.span` only points at `'_`, so to suggest `-> Option<()>`
+                                    // we need to find a more accurate span to end up with
+                                    // fn g<'a>(mut x: impl Iterator<Item = &'_ ()>) -> Option<()>
+                                    sugg = vec![(span.with_hi(mut_ty.ty.span.lo()), String::new())];
+                                    owned_sugg = true;
+                                }
                             }
                             if let Some(ty) = lt_finder.found {
                                 if let TyKind::Path(None, path) = &ty.kind {
@@ -4098,6 +4105,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                                                         lt.span.with_hi(ty.span.hi()),
                                                         "String".to_string(),
                                                     )];
+                                                    sugg_is_str_to_string = true;
                                                 }
                                                 Some(Res::PrimTy(..)) => {}
                                                 Some(Res::Def(
@@ -4124,6 +4132,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                                                         lt.span.with_hi(ty.span.hi()),
                                                         "String".to_string(),
                                                     )];
+                                                    sugg_is_str_to_string = true;
                                                 }
                                                 Res::PrimTy(..) => {}
                                                 Res::Def(
@@ -4158,6 +4167,12 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                             }
                         }
                         if owned_sugg {
+                            if let Some(span) =
+                                self.find_ref_prefix_span_for_owned_suggestion(lt.span)
+                                && !sugg_is_str_to_string
+                            {
+                                sugg = vec![(span, String::new())];
+                            }
                             err.multipart_suggestion_verbose(
                                 format!("{pre} to return an owned value"),
                                 sugg,
@@ -4184,6 +4199,23 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
             }
         }
     }
+
+    fn find_ref_prefix_span_for_owned_suggestion(&self, lifetime: Span) -> Option<Span> {
+        let mut finder = RefPrefixSpanFinder { lifetime, span: None };
+        if let Some(item) = self.diag_metadata.current_item {
+            finder.visit_item(item);
+        } else if let Some((kind, _span)) = self.diag_metadata.current_function
+            && let FnKind::Fn(_, _, ast::Fn { sig, .. }) = kind
+        {
+            for param in &sig.decl.inputs {
+                finder.visit_ty(&param.ty);
+            }
+            if let ast::FnRetTy::Ty(ret_ty) = &sig.decl.output {
+                finder.visit_ty(ret_ty);
+            }
+        }
+        finder.span
+    }
 }
 
 fn mk_where_bound_predicate(
@@ -4285,6 +4317,26 @@ impl<'ast> Visitor<'ast> for LifetimeFinder<'ast> {
     }
 }
 
+struct RefPrefixSpanFinder {
+    lifetime: Span,
+    span: Option<Span>,
+}
+
+impl<'ast> Visitor<'ast> for RefPrefixSpanFinder {
+    fn visit_ty(&mut self, t: &'ast Ty) {
+        if self.span.is_some() {
+            return;
+        }
+        if let TyKind::Ref(_, mut_ty) | TyKind::PinnedRef(_, mut_ty) = &t.kind
+            && t.span.lo() == self.lifetime.lo()
+        {
+            self.span = Some(t.span.with_hi(mut_ty.ty.span.lo()));
+            return;
+        }
+        walk_ty(self, t);
+    }
+}
+
 /// Shadowing involving a label is only a warning for historical reasons.
 //FIXME: make this a proper lint.
 pub(super) fn signal_label_shadowing(sess: &Session, orig: Span, shadower: Ident) {
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 9219b5a7e8aca..69f9ad9aa3613 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -2481,6 +2481,9 @@ options! {
     mir_include_spans: MirIncludeSpans = (MirIncludeSpans::default(), parse_mir_include_spans, [UNTRACKED],
         "include extra comments in mir pretty printing, like line numbers and statement indices, \
          details about types, etc. (boolean for all passes, 'nll' to enable in NLL MIR only, default: 'nll')"),
+    mir_opt_bisect_limit: Option<usize> = (None, parse_opt_number, [TRACKED],
+        "limit the number of MIR optimization pass executions (global across all bodies). \
+        Pass executions after this limit are skipped and reported. (default: no limit)"),
     #[rustc_lint_opt_deny_field_access("use `Session::mir_opt_level` instead of this field")]
     mir_opt_level: Option<usize> = (None, parse_opt_number, [TRACKED],
         "MIR optimization level (0-4; default: 1 in non optimized builds and 2 in optimized builds)"),
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index bb22e4a8db047..427f3e7fa5089 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -2,7 +2,7 @@ use std::any::Any;
 use std::path::PathBuf;
 use std::str::FromStr;
 use std::sync::Arc;
-use std::sync::atomic::AtomicBool;
+use std::sync::atomic::{AtomicBool, AtomicUsize};
 use std::{env, io};
 
 use rand::{RngCore, rng};
@@ -161,6 +161,12 @@ pub struct Session {
 
     /// Does the codegen backend support ThinLTO?
     pub thin_lto_supported: bool,
+
+    /// Global per-session counter for MIR optimization pass applications.
+    ///
+    /// Used by `-Zmir-opt-bisect-limit` to assign an index to each
+    /// optimization-pass execution candidate during this compilation.
+    pub mir_opt_bisect_eval_count: AtomicUsize,
 }
 
 #[derive(Clone, Copy)]
@@ -1101,6 +1107,7 @@ pub fn build_session(
         invocation_temp,
         replaced_intrinsics: FxHashSet::default(), // filled by `run_compiler`
         thin_lto_supported: true,                  // filled by `run_compiler`
+        mir_opt_bisect_eval_count: AtomicUsize::new(0),
     };
 
     validate_commandline_args_with_session_available(&sess);
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 5623b984b2420..1d38b41c25dfb 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -327,7 +327,6 @@ symbols! {
         Pointer,
         Poll,
         ProcMacro,
-        ProceduralMasqueradeDummyType,
         Range,
         RangeBounds,
         RangeCopy,
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
index 6003461f35e8b..fdb2e7d838d52 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
@@ -300,6 +300,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 let rebased_args = alias.args.rebase_onto(tcx, trait_def_id, impl_substs);
 
                 let impl_item_def_id = leaf_def.item.def_id;
+                if !tcx.check_args_compatible(impl_item_def_id, rebased_args) {
+                    return false;
+                }
                 let impl_assoc_ty = tcx.type_of(impl_item_def_id).instantiate(tcx, rebased_args);
 
                 self.infcx.can_eq(param_env, impl_assoc_ty, concrete)
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 04ca6403fe833..73e93657b02f7 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -182,7 +182,6 @@
 #![feature(negative_impls)]
 #![feature(never_type)]
 #![feature(optimize_attribute)]
-#![feature(rustc_allow_const_fn_unstable)]
 #![feature(rustc_attrs)]
 #![feature(slice_internals)]
 #![feature(staged_api)]
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index d650239a44c60..7158fda49a8d2 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -159,7 +159,6 @@
 #![feature(pattern_types)]
 #![feature(prelude_import)]
 #![feature(repr_simd)]
-#![feature(rustc_allow_const_fn_unstable)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
 #![feature(simd_ffi)]
diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
index cf79635dcd877..94396752ac6da 100644
--- a/library/core/src/num/uint_macros.rs
+++ b/library/core/src/num/uint_macros.rs
@@ -487,8 +487,8 @@ macro_rules! uint_impl {
 
         /// Performs a carry-less multiplication, returning the lower bits.
         ///
-        /// This operation is similar to long multiplication, except that exclusive or is used
-        /// instead of addition. The implementation is equivalent to:
+        /// This operation is similar to long multiplication in base 2, except that exclusive or is
+        /// used instead of addition. The implementation is equivalent to:
         ///
         /// ```no_run
         #[doc = concat!("pub fn carryless_mul(lhs: ", stringify!($SelfT), ", rhs: ", stringify!($SelfT), ") -> ", stringify!($SelfT), "{")]
diff --git a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
index 06220f91c7458..1484b8c8bcc45 100644
--- a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
+++ b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
@@ -194,7 +194,6 @@ fn check_rvalue<'tcx>(
                 ))
             }
         },
-        Rvalue::ShallowInitBox(_, _) => Ok(()),
         Rvalue::UnaryOp(_, operand) => {
             let ty = operand.ty(body, cx.tcx);
             if ty.is_integral() || ty.is_bool() {
diff --git a/src/tools/miri/src/concurrency/thread.rs b/src/tools/miri/src/concurrency/thread.rs
index 1c404d419ef83..9d829bf69e5eb 100644
--- a/src/tools/miri/src/concurrency/thread.rs
+++ b/src/tools/miri/src/concurrency/thread.rs
@@ -343,8 +343,8 @@ impl VisitProvenance for Thread<'_> {
 
 impl VisitProvenance for Frame<'_, Provenance, FrameExtra<'_>> {
     fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
+        let return_place = self.return_place();
         let Frame {
-            return_place,
             locals,
             extra,
             // There are some private fields we cannot access; they contain no tags.
diff --git a/src/tools/miri/src/diagnostics.rs b/src/tools/miri/src/diagnostics.rs
index 64c7096fc5c2e..71ec9723de8e9 100644
--- a/src/tools/miri/src/diagnostics.rs
+++ b/src/tools/miri/src/diagnostics.rs
@@ -493,7 +493,7 @@ pub fn report_result<'tcx>(
     for (i, frame) in ecx.active_thread_stack().iter().enumerate() {
         trace!("-------------------");
         trace!("Frame {}", i);
-        trace!("    return: {:?}", frame.return_place);
+        trace!("    return: {:?}", frame.return_place());
         for (i, local) in frame.locals.iter().enumerate() {
             trace!("    local {}: {:?}", i, local);
         }
diff --git a/src/tools/miri/src/machine.rs b/src/tools/miri/src/machine.rs
index d50475c748747..7883673cdd6a2 100644
--- a/src/tools/miri/src/machine.rs
+++ b/src/tools/miri/src/machine.rs
@@ -1235,7 +1235,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
             // to run extra MIR), and Ok(Some(body)) if we found MIR to run for the
             // foreign function
             // Any needed call to `goto_block` will be performed by `emulate_foreign_item`.
-            let args = ecx.copy_fn_args(args); // FIXME: Should `InPlace` arguments be reset to uninit?
+            let args = MiriInterpCx::copy_fn_args(args); // FIXME: Should `InPlace` arguments be reset to uninit?
             let link_name = Symbol::intern(ecx.tcx.symbol_name(instance).name);
             return ecx.emulate_foreign_item(link_name, abi, &args, dest, ret, unwind);
         }
@@ -1262,7 +1262,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
         ret: Option<mir::BasicBlock>,
         unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx> {
-        let args = ecx.copy_fn_args(args); // FIXME: Should `InPlace` arguments be reset to uninit?
+        let args = MiriInterpCx::copy_fn_args(args); // FIXME: Should `InPlace` arguments be reset to uninit?
         ecx.emulate_dyn_sym(fn_val, abi, &args, dest, ret, unwind)
     }
 
diff --git a/src/tools/miri/tests/fail/tail_calls/dangling-local-var.stderr b/src/tools/miri/tests/fail/tail_calls/dangling-local-var.stderr
index 1577cceae5944..7b0efec7be5a5 100644
--- a/src/tools/miri/tests/fail/tail_calls/dangling-local-var.stderr
+++ b/src/tools/miri/tests/fail/tail_calls/dangling-local-var.stderr
@@ -14,8 +14,8 @@ LL |     let local = 0;
 help: ALLOC was deallocated here:
   --> tests/fail/tail_calls/dangling-local-var.rs:LL:CC
    |
-LL |     f(std::ptr::null());
-   |     ^^^^^^^^^^^^^^^^^^^
+LL |     let _val = unsafe { *x };
+   |         ^^^^
    = note: stack backtrace:
            0: g
                at tests/fail/tail_calls/dangling-local-var.rs:LL:CC
diff --git a/src/tools/miri/tests/fail/validity/recursive-validity-box-bool.rs b/src/tools/miri/tests/fail/validity/recursive-validity-box-bool.rs
new file mode 100644
index 0000000000000..dee2c9aad2c7d
--- /dev/null
+++ b/src/tools/miri/tests/fail/validity/recursive-validity-box-bool.rs
@@ -0,0 +1,8 @@
+//@compile-flags: -Zmiri-recursive-validation
+
+fn main() {
+    let x = 3u8;
+    let xref = &x;
+    let xref_wrong_type: Box<bool> = unsafe { std::mem::transmute(xref) }; //~ERROR: encountered 0x03, but expected a boolean
+    let _val = *xref_wrong_type;
+}
diff --git a/src/tools/miri/tests/fail/validity/recursive-validity-box-bool.stderr b/src/tools/miri/tests/fail/validity/recursive-validity-box-bool.stderr
new file mode 100644
index 0000000000000..d658909efd937
--- /dev/null
+++ b/src/tools/miri/tests/fail/validity/recursive-validity-box-bool.stderr
@@ -0,0 +1,13 @@
+error: Undefined Behavior: constructing invalid value at .<deref>: encountered 0x03, but expected a boolean
+  --> tests/fail/validity/recursive-validity-box-bool.rs:LL:CC
+   |
+LL |     let xref_wrong_type: Box<bool> = unsafe { std::mem::transmute(xref) };
+   |                                               ^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = 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: 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/pass/tail_call.rs b/src/tools/miri/tests/pass/function_calls/tail_call.rs
similarity index 84%
rename from src/tools/miri/tests/pass/tail_call.rs
rename to src/tools/miri/tests/pass/function_calls/tail_call.rs
index f620070639801..f9cf86bb898f4 100644
--- a/src/tools/miri/tests/pass/tail_call.rs
+++ b/src/tools/miri/tests/pass/function_calls/tail_call.rs
@@ -4,6 +4,7 @@
 fn main() {
     assert_eq!(factorial(10), 3_628_800);
     assert_eq!(mutually_recursive_identity(1000), 1000);
+    non_scalar();
 }
 
 fn factorial(n: u32) -> u32 {
@@ -37,3 +38,14 @@ fn mutually_recursive_identity(x: u32) -> u32 {
 
     switch(x, 0)
 }
+
+fn non_scalar() {
+    fn f(x: [usize; 2], i: u32) {
+        if i == 0 {
+            return;
+        }
+        become f(x, i - 1);
+    }
+
+    f([5, 5], 2);
+}
diff --git a/tests/codegen-llvm/intrinsics/likely_assert.rs b/tests/codegen-llvm/intrinsics/likely_assert.rs
index 59a40c750eab4..e7e2cfdff052d 100644
--- a/tests/codegen-llvm/intrinsics/likely_assert.rs
+++ b/tests/codegen-llvm/intrinsics/likely_assert.rs
@@ -1,5 +1,5 @@
 //@ compile-flags: -Copt-level=3
-#![feature(panic_internals, const_eval_select, rustc_allow_const_fn_unstable, core_intrinsics)]
+#![feature(panic_internals, const_eval_select, rustc_attrs, core_intrinsics)]
 #![crate_type = "lib"]
 
 // check that assert! and const_assert! emit branch weights
diff --git a/tests/mir-opt/optimize_none.rs b/tests/mir-opt/optimize_none.rs
index a5b541bd2b628..99efcc35e5955 100644
--- a/tests/mir-opt/optimize_none.rs
+++ b/tests/mir-opt/optimize_none.rs
@@ -15,13 +15,14 @@ pub fn add_noopt() -> i32 {
 #[optimize(none)]
 pub fn const_branch() -> i32 {
     // CHECK-LABEL: fn const_branch(
-    // CHECK: switchInt(const true) -> [0: [[FALSE:bb[0-9]+]], otherwise: [[TRUE:bb[0-9]+]]];
+    // CHECK: [[BOOL:_[0-9]+]] = const true;
+    // CHECK: switchInt(move [[BOOL]]) -> [0: [[BB_FALSE:bb[0-9]+]], otherwise: [[BB_TRUE:bb[0-9]+]]];
     // CHECK-NEXT: }
-    // CHECK: [[FALSE]]: {
+    // CHECK: [[BB_FALSE]]: {
     // CHECK-NEXT: _0 = const 0
     // CHECK-NEXT: goto
     // CHECK-NEXT: }
-    // CHECK: [[TRUE]]: {
+    // CHECK: [[BB_TRUE]]: {
     // CHECK-NEXT: _0 = const 1
     // CHECK-NEXT: goto
     // CHECK-NEXT: }
diff --git a/tests/run-make/mir-opt-bisect-limit/main.rs b/tests/run-make/mir-opt-bisect-limit/main.rs
new file mode 100644
index 0000000000000..674275b10fcd5
--- /dev/null
+++ b/tests/run-make/mir-opt-bisect-limit/main.rs
@@ -0,0 +1,11 @@
+#![crate_type = "lib"]
+#![no_std]
+
+#[inline(never)]
+pub fn callee(x: u64) -> u64 {
+    x.wrapping_mul(3).wrapping_add(7)
+}
+
+pub fn caller(a: u64, b: u64) -> u64 {
+    callee(a) + callee(b)
+}
diff --git a/tests/run-make/mir-opt-bisect-limit/rmake.rs b/tests/run-make/mir-opt-bisect-limit/rmake.rs
new file mode 100644
index 0000000000000..fa77cb7d8c35c
--- /dev/null
+++ b/tests/run-make/mir-opt-bisect-limit/rmake.rs
@@ -0,0 +1,119 @@
+use std::path::Path;
+
+use run_make_support::{CompletedProcess, rfs, rustc};
+
+struct Case {
+    name: &'static str,
+    flags: &'static [&'static str],
+    expect_inline_dump: bool,
+    expect_running: ExpectedCount,
+    expect_not_running: ExpectedCount,
+}
+
+enum ExpectedCount {
+    Exactly(usize),
+    AtLeastOne,
+    Zero,
+}
+
+fn main() {
+    let cases = [
+        Case {
+            name: "limit0",
+            flags: &["-Zmir-opt-bisect-limit=0"],
+            expect_inline_dump: false,
+            expect_running: ExpectedCount::Exactly(0),
+            expect_not_running: ExpectedCount::AtLeastOne,
+        },
+        Case {
+            name: "limit1",
+            flags: &["-Zmir-opt-bisect-limit=1"],
+            expect_inline_dump: false,
+            expect_running: ExpectedCount::Exactly(1),
+            expect_not_running: ExpectedCount::AtLeastOne,
+        },
+        Case {
+            name: "huge_limit",
+            flags: &["-Zmir-opt-bisect-limit=1000000000"],
+            expect_inline_dump: true,
+            expect_running: ExpectedCount::AtLeastOne,
+            expect_not_running: ExpectedCount::Zero,
+        },
+        Case {
+            name: "limit0_with_force_enable_inline",
+            flags: &["-Zmir-opt-bisect-limit=0", "-Zmir-enable-passes=+Inline"],
+            expect_inline_dump: false,
+            expect_running: ExpectedCount::Exactly(0),
+            expect_not_running: ExpectedCount::AtLeastOne,
+        },
+    ];
+
+    for case in cases {
+        let (inline_dumped, running_count, not_running_count, output) =
+            compile_case(case.name, case.flags);
+
+        assert_eq!(
+            inline_dumped, case.expect_inline_dump,
+            "{}: unexpected Inline dump presence",
+            case.name
+        );
+
+        assert_expected_count(
+            running_count,
+            case.expect_running,
+            &format!("{}: running count", case.name),
+        );
+        assert_expected_count(
+            not_running_count,
+            case.expect_not_running,
+            &format!("{}: NOT running count", case.name),
+        );
+    }
+}
+
+fn compile_case(dump_dir: &str, extra_flags: &[&str]) -> (bool, usize, usize, CompletedProcess) {
+    if Path::new(dump_dir).exists() {
+        rfs::remove_dir_all(dump_dir);
+    }
+    rfs::create_dir_all(dump_dir);
+
+    let mut cmd = rustc();
+    cmd.input("main.rs")
+        .arg("--emit=mir")
+        .arg("-Zmir-opt-level=2")
+        .arg("-Copt-level=2")
+        .arg("-Zthreads=1")
+        .arg("-Zdump-mir=Inline")
+        .arg(format!("-Zdump-mir-dir={dump_dir}"));
+
+    for &flag in extra_flags {
+        cmd.arg(flag);
+    }
+
+    let output = cmd.run();
+    let (running_count, not_running_count) = bisect_line_counts(&output);
+    (has_inline_dump_file(dump_dir), running_count, not_running_count, output)
+}
+
+fn assert_expected_count(actual: usize, expected: ExpectedCount, context: &str) {
+    match expected {
+        ExpectedCount::Exactly(n) => assert_eq!(actual, n, "{context}"),
+        ExpectedCount::AtLeastOne => assert!(actual > 0, "{context}"),
+        ExpectedCount::Zero => assert_eq!(actual, 0, "{context}"),
+    }
+}
+
+fn has_inline_dump_file(dir: &str) -> bool {
+    rfs::read_dir(dir)
+        .flatten()
+        .any(|entry| entry.file_name().to_string_lossy().contains(".Inline."))
+}
+
+fn bisect_line_counts(output: &CompletedProcess) -> (usize, usize) {
+    let stderr = output.stderr_utf8();
+    let running_count =
+        stderr.lines().filter(|line| line.starts_with("BISECT: running pass (")).count();
+    let not_running_count =
+        stderr.lines().filter(|line| line.starts_with("BISECT: NOT running pass (")).count();
+    (running_count, not_running_count)
+}
diff --git a/tests/ui/associated-types/suggest-param-env-shadowing-incompatible-args.rs b/tests/ui/associated-types/suggest-param-env-shadowing-incompatible-args.rs
new file mode 100644
index 0000000000000..4a3ccc287f7f0
--- /dev/null
+++ b/tests/ui/associated-types/suggest-param-env-shadowing-incompatible-args.rs
@@ -0,0 +1,18 @@
+//@ compile-flags: -Znext-solver=globally
+
+// Regression test for https://github.com/rust-lang/rust/issues/152684.
+
+#![feature(associated_type_defaults)]
+
+trait Foo {
+    type Assoc<T = u8> = T;
+    //~^ ERROR defaults for generic parameters are not allowed here
+    fn foo() -> Self::Assoc;
+}
+impl Foo for () {
+    fn foo() -> Self::Assoc {
+        [] //~ ERROR mismatched types
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/associated-types/suggest-param-env-shadowing-incompatible-args.stderr b/tests/ui/associated-types/suggest-param-env-shadowing-incompatible-args.stderr
new file mode 100644
index 0000000000000..c401233242489
--- /dev/null
+++ b/tests/ui/associated-types/suggest-param-env-shadowing-incompatible-args.stderr
@@ -0,0 +1,20 @@
+error: defaults for generic parameters are not allowed here
+  --> $DIR/suggest-param-env-shadowing-incompatible-args.rs:8:16
+   |
+LL |     type Assoc<T = u8> = T;
+   |                ^^^^^^
+
+error[E0308]: mismatched types
+  --> $DIR/suggest-param-env-shadowing-incompatible-args.rs:14:9
+   |
+LL |     fn foo() -> Self::Assoc {
+   |                 ----------- expected `<() as Foo>::Assoc` because of return type
+LL |         []
+   |         ^^ expected `u8`, found `[_; 0]`
+   |
+   = note: expected type `u8`
+             found array `[_; 0]`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/attributes/malformed-attrs.rs b/tests/ui/attributes/malformed-attrs.rs
index 489c8bf9f4954..6193a101918bd 100644
--- a/tests/ui/attributes/malformed-attrs.rs
+++ b/tests/ui/attributes/malformed-attrs.rs
@@ -2,7 +2,6 @@
 // We enable a bunch of features to not get feature-gate errs in this test.
 #![deny(invalid_doc_attributes)]
 #![feature(rustc_attrs)]
-#![feature(rustc_allow_const_fn_unstable)]
 #![feature(allow_internal_unstable)]
 // FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
 #![feature(fn_align)]
diff --git a/tests/ui/attributes/malformed-attrs.stderr b/tests/ui/attributes/malformed-attrs.stderr
index 009da1d12a16e..01e70adf4ee99 100644
--- a/tests/ui/attributes/malformed-attrs.stderr
+++ b/tests/ui/attributes/malformed-attrs.stderr
@@ -1,5 +1,5 @@
 error[E0539]: malformed `cfg` attribute input
-  --> $DIR/malformed-attrs.rs:107:1
+  --> $DIR/malformed-attrs.rs:106:1
    |
 LL | #[cfg]
    | ^^^^^^
@@ -10,7 +10,7 @@ LL | #[cfg]
    = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg-attribute>
 
 error[E0539]: malformed `cfg_attr` attribute input
-  --> $DIR/malformed-attrs.rs:109:1
+  --> $DIR/malformed-attrs.rs:108:1
    |
 LL | #[cfg_attr]
    | ^^^^^^^^^^^
@@ -21,13 +21,13 @@ LL | #[cfg_attr]
    = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
 error[E0463]: can't find crate for `wloop`
-  --> $DIR/malformed-attrs.rs:215:1
+  --> $DIR/malformed-attrs.rs:214:1
    |
 LL | extern crate wloop;
    | ^^^^^^^^^^^^^^^^^^^ can't find crate
 
 error: malformed `allow` attribute input
-  --> $DIR/malformed-attrs.rs:181:1
+  --> $DIR/malformed-attrs.rs:180:1
    |
 LL | #[allow]
    | ^^^^^^^^
@@ -43,7 +43,7 @@ LL | #[allow(lint1, lint2, lint3, reason = "...")]
    |        +++++++++++++++++++++++++++++++++++++
 
 error: malformed `expect` attribute input
-  --> $DIR/malformed-attrs.rs:183:1
+  --> $DIR/malformed-attrs.rs:182:1
    |
 LL | #[expect]
    | ^^^^^^^^^
@@ -59,7 +59,7 @@ LL | #[expect(lint1, lint2, lint3, reason = "...")]
    |         +++++++++++++++++++++++++++++++++++++
 
 error: malformed `warn` attribute input
-  --> $DIR/malformed-attrs.rs:185:1
+  --> $DIR/malformed-attrs.rs:184:1
    |
 LL | #[warn]
    | ^^^^^^^
@@ -75,7 +75,7 @@ LL | #[warn(lint1, lint2, lint3, reason = "...")]
    |       +++++++++++++++++++++++++++++++++++++
 
 error: malformed `deny` attribute input
-  --> $DIR/malformed-attrs.rs:187:1
+  --> $DIR/malformed-attrs.rs:186:1
    |
 LL | #[deny]
    | ^^^^^^^
@@ -91,7 +91,7 @@ LL | #[deny(lint1, lint2, lint3, reason = "...")]
    |       +++++++++++++++++++++++++++++++++++++
 
 error: malformed `forbid` attribute input
-  --> $DIR/malformed-attrs.rs:189:1
+  --> $DIR/malformed-attrs.rs:188:1
    |
 LL | #[forbid]
    | ^^^^^^^^^
@@ -107,25 +107,25 @@ LL | #[forbid(lint1, lint2, lint3, reason = "...")]
    |         +++++++++++++++++++++++++++++++++++++
 
 error: the `#[proc_macro]` attribute is only usable with crates of the `proc-macro` crate type
-  --> $DIR/malformed-attrs.rs:104:1
+  --> $DIR/malformed-attrs.rs:103:1
    |
 LL | #[proc_macro = 18]
    | ^^^^^^^^^^^^^^^^^^
 
 error: the `#[proc_macro_attribute]` attribute is only usable with crates of the `proc-macro` crate type
-  --> $DIR/malformed-attrs.rs:121:1
+  --> $DIR/malformed-attrs.rs:120:1
    |
 LL | #[proc_macro_attribute = 19]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: the `#[proc_macro_derive]` attribute is only usable with crates of the `proc-macro` crate type
-  --> $DIR/malformed-attrs.rs:128:1
+  --> $DIR/malformed-attrs.rs:127:1
    |
 LL | #[proc_macro_derive]
    | ^^^^^^^^^^^^^^^^^^^^
 
 error[E0658]: allow_internal_unsafe side-steps the unsafe_code lint
-  --> $DIR/malformed-attrs.rs:220:1
+  --> $DIR/malformed-attrs.rs:219:1
    |
 LL | #[allow_internal_unsafe = 1]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -134,7 +134,7 @@ LL | #[allow_internal_unsafe = 1]
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0539]: malformed `windows_subsystem` attribute input
-  --> $DIR/malformed-attrs.rs:27:1
+  --> $DIR/malformed-attrs.rs:26:1
    |
 LL | #![windows_subsystem]
    | ^^^-----------------^
@@ -150,25 +150,25 @@ LL | #![windows_subsystem = "windows"]
    |                      +++++++++++
 
 error[E0539]: malformed `export_name` attribute input
-  --> $DIR/malformed-attrs.rs:30:1
+  --> $DIR/malformed-attrs.rs:29:1
    |
 LL | #[unsafe(export_name)]
    | ^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[export_name = "name"]`
 
 error: `rustc_allow_const_fn_unstable` expects a list of feature names
-  --> $DIR/malformed-attrs.rs:32:1
+  --> $DIR/malformed-attrs.rs:31:1
    |
 LL | #[rustc_allow_const_fn_unstable]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `allow_internal_unstable` expects a list of feature names
-  --> $DIR/malformed-attrs.rs:35:1
+  --> $DIR/malformed-attrs.rs:34:1
    |
 LL | #[allow_internal_unstable]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0539]: malformed `rustc_confusables` attribute input
-  --> $DIR/malformed-attrs.rs:37:1
+  --> $DIR/malformed-attrs.rs:36:1
    |
 LL | #[rustc_confusables]
    | ^^^^^^^^^^^^^^^^^^^^
@@ -177,7 +177,7 @@ LL | #[rustc_confusables]
    | help: must be of the form: `#[rustc_confusables("name1", "name2", ...)]`
 
 error: `#[rustc_confusables]` attribute cannot be used on functions
-  --> $DIR/malformed-attrs.rs:37:1
+  --> $DIR/malformed-attrs.rs:36:1
    |
 LL | #[rustc_confusables]
    | ^^^^^^^^^^^^^^^^^^^^
@@ -185,7 +185,7 @@ LL | #[rustc_confusables]
    = help: `#[rustc_confusables]` can only be applied to inherent methods
 
 error[E0539]: malformed `deprecated` attribute input
-  --> $DIR/malformed-attrs.rs:40:1
+  --> $DIR/malformed-attrs.rs:39:1
    |
 LL | #[deprecated = 5]
    | ^^^^^^^^^^^^^^^-^
@@ -193,7 +193,7 @@ LL | #[deprecated = 5]
    |                expected a string literal here
 
 error[E0539]: malformed `rustc_macro_transparency` attribute input
-  --> $DIR/malformed-attrs.rs:44:1
+  --> $DIR/malformed-attrs.rs:43:1
    |
 LL | #[rustc_macro_transparency]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -208,7 +208,7 @@ LL | #[rustc_macro_transparency = "transparent"]
    |                            +++++++++++++++
 
 error: `#[rustc_macro_transparency]` attribute cannot be used on functions
-  --> $DIR/malformed-attrs.rs:44:1
+  --> $DIR/malformed-attrs.rs:43:1
    |
 LL | #[rustc_macro_transparency]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -216,7 +216,7 @@ LL | #[rustc_macro_transparency]
    = help: `#[rustc_macro_transparency]` can only be applied to macro defs
 
 error[E0539]: malformed `repr` attribute input
-  --> $DIR/malformed-attrs.rs:47:1
+  --> $DIR/malformed-attrs.rs:46:1
    |
 LL | #[repr]
    | ^^^^^^^ expected this to be a list
@@ -224,7 +224,7 @@ LL | #[repr]
    = note: for more information, visit <https://doc.rust-lang.org/reference/type-layout.html#representations>
 
 error[E0565]: malformed `rustc_as_ptr` attribute input
-  --> $DIR/malformed-attrs.rs:50:1
+  --> $DIR/malformed-attrs.rs:49:1
    |
 LL | #[rustc_as_ptr = 5]
    | ^^^^^^^^^^^^^^^---^
@@ -233,7 +233,7 @@ LL | #[rustc_as_ptr = 5]
    | help: must be of the form: `#[rustc_as_ptr]`
 
 error[E0539]: malformed `rustc_align` attribute input
-  --> $DIR/malformed-attrs.rs:55:1
+  --> $DIR/malformed-attrs.rs:54:1
    |
 LL | #[rustc_align]
    | ^^^^^^^^^^^^^^
@@ -242,7 +242,7 @@ LL | #[rustc_align]
    | help: must be of the form: `#[rustc_align(<alignment in bytes>)]`
 
 error[E0539]: malformed `optimize` attribute input
-  --> $DIR/malformed-attrs.rs:57:1
+  --> $DIR/malformed-attrs.rs:56:1
    |
 LL | #[optimize]
    | ^^^^^^^^^^^ expected this to be a list
@@ -257,7 +257,7 @@ LL | #[optimize(speed)]
    |           +++++++
 
 error[E0565]: malformed `cold` attribute input
-  --> $DIR/malformed-attrs.rs:59:1
+  --> $DIR/malformed-attrs.rs:58:1
    |
 LL | #[cold = 1]
    | ^^^^^^^---^
@@ -266,7 +266,7 @@ LL | #[cold = 1]
    | help: must be of the form: `#[cold]`
 
 error[E0539]: malformed `must_use` attribute input
-  --> $DIR/malformed-attrs.rs:61:1
+  --> $DIR/malformed-attrs.rs:60:1
    |
 LL | #[must_use()]
    | ^^^^^^^^^^--^
@@ -284,7 +284,7 @@ LL + #[must_use]
    |
 
 error[E0565]: malformed `no_mangle` attribute input
-  --> $DIR/malformed-attrs.rs:63:1
+  --> $DIR/malformed-attrs.rs:62:1
    |
 LL | #[no_mangle = 1]
    | ^^^^^^^^^^^^---^
@@ -293,7 +293,7 @@ LL | #[no_mangle = 1]
    | help: must be of the form: `#[no_mangle]`
 
 error[E0565]: malformed `naked` attribute input
-  --> $DIR/malformed-attrs.rs:65:1
+  --> $DIR/malformed-attrs.rs:64:1
    |
 LL | #[unsafe(naked())]
    | ^^^^^^^^^^^^^^--^^
@@ -302,7 +302,7 @@ LL | #[unsafe(naked())]
    | help: must be of the form: `#[naked]`
 
 error[E0565]: malformed `track_caller` attribute input
-  --> $DIR/malformed-attrs.rs:67:1
+  --> $DIR/malformed-attrs.rs:66:1
    |
 LL | #[track_caller()]
    | ^^^^^^^^^^^^^^--^
@@ -311,13 +311,13 @@ LL | #[track_caller()]
    | help: must be of the form: `#[track_caller]`
 
 error[E0539]: malformed `export_name` attribute input
-  --> $DIR/malformed-attrs.rs:69:1
+  --> $DIR/malformed-attrs.rs:68:1
    |
 LL | #[export_name()]
    | ^^^^^^^^^^^^^^^^ help: must be of the form: `#[export_name = "name"]`
 
 error[E0805]: malformed `used` attribute input
-  --> $DIR/malformed-attrs.rs:71:1
+  --> $DIR/malformed-attrs.rs:70:1
    |
 LL | #[used()]
    | ^^^^^^--^
@@ -335,7 +335,7 @@ LL + #[used]
    |
 
 error: `#[used]` attribute cannot be used on functions
-  --> $DIR/malformed-attrs.rs:71:1
+  --> $DIR/malformed-attrs.rs:70:1
    |
 LL | #[used()]
    | ^^^^^^^^^
@@ -343,13 +343,13 @@ LL | #[used()]
    = help: `#[used]` can only be applied to statics
 
 error[E0539]: malformed `crate_name` attribute input
-  --> $DIR/malformed-attrs.rs:74:1
+  --> $DIR/malformed-attrs.rs:73:1
    |
 LL | #[crate_name]
    | ^^^^^^^^^^^^^ help: must be of the form: `#[crate_name = "name"]`
 
 error[E0539]: malformed `target_feature` attribute input
-  --> $DIR/malformed-attrs.rs:79:1
+  --> $DIR/malformed-attrs.rs:78:1
    |
 LL | #[target_feature]
    | ^^^^^^^^^^^^^^^^^
@@ -358,7 +358,7 @@ LL | #[target_feature]
    | help: must be of the form: `#[target_feature(enable = "feat1, feat2")]`
 
 error[E0565]: malformed `export_stable` attribute input
-  --> $DIR/malformed-attrs.rs:81:1
+  --> $DIR/malformed-attrs.rs:80:1
    |
 LL | #[export_stable = 1]
    | ^^^^^^^^^^^^^^^^---^
@@ -367,7 +367,7 @@ LL | #[export_stable = 1]
    | help: must be of the form: `#[export_stable]`
 
 error[E0539]: malformed `link` attribute input
-  --> $DIR/malformed-attrs.rs:83:1
+  --> $DIR/malformed-attrs.rs:82:1
    |
 LL | #[link]
    | ^^^^^^^ expected this to be a list
@@ -375,7 +375,7 @@ LL | #[link]
    = note: for more information, visit <https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute>
 
 error[E0539]: malformed `link_name` attribute input
-  --> $DIR/malformed-attrs.rs:87:1
+  --> $DIR/malformed-attrs.rs:86:1
    |
 LL | #[link_name]
    | ^^^^^^^^^^^^ help: must be of the form: `#[link_name = "name"]`
@@ -383,7 +383,7 @@ LL | #[link_name]
    = note: for more information, visit <https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_name-attribute>
 
 error[E0539]: malformed `link_section` attribute input
-  --> $DIR/malformed-attrs.rs:91:1
+  --> $DIR/malformed-attrs.rs:90:1
    |
 LL | #[link_section]
    | ^^^^^^^^^^^^^^^ help: must be of the form: `#[link_section = "name"]`
@@ -391,7 +391,7 @@ LL | #[link_section]
    = note: for more information, visit <https://doc.rust-lang.org/reference/abi.html#the-link_section-attribute>
 
 error[E0539]: malformed `coverage` attribute input
-  --> $DIR/malformed-attrs.rs:93:1
+  --> $DIR/malformed-attrs.rs:92:1
    |
 LL | #[coverage]
    | ^^^^^^^^^^^ this attribute is only valid with either `on` or `off` as an argument
@@ -404,13 +404,13 @@ LL | #[coverage(on)]
    |           ++++
 
 error[E0539]: malformed `sanitize` attribute input
-  --> $DIR/malformed-attrs.rs:95:1
+  --> $DIR/malformed-attrs.rs:94:1
    |
 LL | #[sanitize]
    | ^^^^^^^^^^^ expected this to be a list
 
 error[E0565]: malformed `no_implicit_prelude` attribute input
-  --> $DIR/malformed-attrs.rs:100:1
+  --> $DIR/malformed-attrs.rs:99:1
    |
 LL | #[no_implicit_prelude = 23]
    | ^^^^^^^^^^^^^^^^^^^^^^----^
@@ -419,7 +419,7 @@ LL | #[no_implicit_prelude = 23]
    | help: must be of the form: `#[no_implicit_prelude]`
 
 error[E0565]: malformed `proc_macro` attribute input
-  --> $DIR/malformed-attrs.rs:104:1
+  --> $DIR/malformed-attrs.rs:103:1
    |
 LL | #[proc_macro = 18]
    | ^^^^^^^^^^^^^----^
@@ -428,7 +428,7 @@ LL | #[proc_macro = 18]
    | help: must be of the form: `#[proc_macro]`
 
 error[E0539]: malformed `instruction_set` attribute input
-  --> $DIR/malformed-attrs.rs:111:1
+  --> $DIR/malformed-attrs.rs:110:1
    |
 LL | #[instruction_set]
    | ^^^^^^^^^^^^^^^^^^
@@ -439,7 +439,7 @@ LL | #[instruction_set]
    = note: for more information, visit <https://doc.rust-lang.org/reference/attributes/codegen.html#the-instruction_set-attribute>
 
 error[E0539]: malformed `patchable_function_entry` attribute input
-  --> $DIR/malformed-attrs.rs:113:1
+  --> $DIR/malformed-attrs.rs:112:1
    |
 LL | #[patchable_function_entry]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -448,7 +448,7 @@ LL | #[patchable_function_entry]
    | help: must be of the form: `#[patchable_function_entry(prefix_nops = m, entry_nops = n)]`
 
 error[E0565]: malformed `coroutine` attribute input
-  --> $DIR/malformed-attrs.rs:116:5
+  --> $DIR/malformed-attrs.rs:115:5
    |
 LL |     #[coroutine = 63] || {}
    |     ^^^^^^^^^^^^----^
@@ -457,7 +457,7 @@ LL |     #[coroutine = 63] || {}
    |     help: must be of the form: `#[coroutine]`
 
 error[E0565]: malformed `proc_macro_attribute` attribute input
-  --> $DIR/malformed-attrs.rs:121:1
+  --> $DIR/malformed-attrs.rs:120:1
    |
 LL | #[proc_macro_attribute = 19]
    | ^^^^^^^^^^^^^^^^^^^^^^^----^
@@ -466,7 +466,7 @@ LL | #[proc_macro_attribute = 19]
    | help: must be of the form: `#[proc_macro_attribute]`
 
 error[E0539]: malformed `must_use` attribute input
-  --> $DIR/malformed-attrs.rs:124:1
+  --> $DIR/malformed-attrs.rs:123:1
    |
 LL | #[must_use = 1]
    | ^^^^^^^^^^^^^-^
@@ -484,7 +484,7 @@ LL + #[must_use]
    |
 
 error[E0539]: malformed `proc_macro_derive` attribute input
-  --> $DIR/malformed-attrs.rs:128:1
+  --> $DIR/malformed-attrs.rs:127:1
    |
 LL | #[proc_macro_derive]
    | ^^^^^^^^^^^^^^^^^^^^ expected this to be a list
@@ -498,7 +498,7 @@ LL | #[proc_macro_derive(TraitName, attributes(name1, name2, ...))]
    |                    ++++++++++++++++++++++++++++++++++++++++++
 
 error[E0539]: malformed `rustc_layout_scalar_valid_range_start` attribute input
-  --> $DIR/malformed-attrs.rs:133:1
+  --> $DIR/malformed-attrs.rs:132:1
    |
 LL | #[rustc_layout_scalar_valid_range_start]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -507,7 +507,7 @@ LL | #[rustc_layout_scalar_valid_range_start]
    | help: must be of the form: `#[rustc_layout_scalar_valid_range_start(start)]`
 
 error[E0539]: malformed `rustc_layout_scalar_valid_range_end` attribute input
-  --> $DIR/malformed-attrs.rs:135:1
+  --> $DIR/malformed-attrs.rs:134:1
    |
 LL | #[rustc_layout_scalar_valid_range_end]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -516,7 +516,7 @@ LL | #[rustc_layout_scalar_valid_range_end]
    | help: must be of the form: `#[rustc_layout_scalar_valid_range_end(end)]`
 
 error[E0539]: malformed `must_not_suspend` attribute input
-  --> $DIR/malformed-attrs.rs:137:1
+  --> $DIR/malformed-attrs.rs:136:1
    |
 LL | #[must_not_suspend()]
    | ^^^^^^^^^^^^^^^^^^--^
@@ -532,7 +532,7 @@ LL + #[must_not_suspend]
    |
 
 error[E0539]: malformed `cfi_encoding` attribute input
-  --> $DIR/malformed-attrs.rs:139:1
+  --> $DIR/malformed-attrs.rs:138:1
    |
 LL | #[cfi_encoding = ""]
    | ^^^^^^^^^^^^^^^^^--^
@@ -541,7 +541,7 @@ LL | #[cfi_encoding = ""]
    | help: must be of the form: `#[cfi_encoding = "encoding"]`
 
 error[E0565]: malformed `marker` attribute input
-  --> $DIR/malformed-attrs.rs:158:1
+  --> $DIR/malformed-attrs.rs:157:1
    |
 LL | #[marker = 3]
    | ^^^^^^^^^---^
@@ -550,7 +550,7 @@ LL | #[marker = 3]
    | help: must be of the form: `#[marker]`
 
 error[E0565]: malformed `fundamental` attribute input
-  --> $DIR/malformed-attrs.rs:160:1
+  --> $DIR/malformed-attrs.rs:159:1
    |
 LL | #[fundamental()]
    | ^^^^^^^^^^^^^--^
@@ -559,7 +559,7 @@ LL | #[fundamental()]
    | help: must be of the form: `#[fundamental]`
 
 error[E0565]: malformed `ffi_pure` attribute input
-  --> $DIR/malformed-attrs.rs:168:5
+  --> $DIR/malformed-attrs.rs:167:5
    |
 LL |     #[unsafe(ffi_pure = 1)]
    |     ^^^^^^^^^^^^^^^^^^---^^
@@ -568,7 +568,7 @@ LL |     #[unsafe(ffi_pure = 1)]
    |     help: must be of the form: `#[ffi_pure]`
 
 error[E0539]: malformed `link_ordinal` attribute input
-  --> $DIR/malformed-attrs.rs:170:5
+  --> $DIR/malformed-attrs.rs:169:5
    |
 LL |     #[link_ordinal]
    |     ^^^^^^^^^^^^^^^
@@ -579,7 +579,7 @@ LL |     #[link_ordinal]
    = note: for more information, visit <https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_ordinal-attribute>
 
 error[E0565]: malformed `ffi_const` attribute input
-  --> $DIR/malformed-attrs.rs:174:5
+  --> $DIR/malformed-attrs.rs:173:5
    |
 LL |     #[unsafe(ffi_const = 1)]
    |     ^^^^^^^^^^^^^^^^^^^---^^
@@ -588,13 +588,13 @@ LL |     #[unsafe(ffi_const = 1)]
    |     help: must be of the form: `#[ffi_const]`
 
 error[E0539]: malformed `linkage` attribute input
-  --> $DIR/malformed-attrs.rs:176:5
+  --> $DIR/malformed-attrs.rs:175:5
    |
 LL |     #[linkage]
    |     ^^^^^^^^^^ expected this to be of the form `linkage = "..."`
 
 error[E0539]: malformed `debugger_visualizer` attribute input
-  --> $DIR/malformed-attrs.rs:191:1
+  --> $DIR/malformed-attrs.rs:190:1
    |
 LL | #[debugger_visualizer]
    | ^^^^^^^^^^^^^^^^^^^^^^
@@ -605,7 +605,7 @@ LL | #[debugger_visualizer]
    = note: for more information, visit <https://doc.rust-lang.org/reference/attributes/debugger.html#the-debugger_visualizer-attribute>
 
 error[E0565]: malformed `automatically_derived` attribute input
-  --> $DIR/malformed-attrs.rs:193:1
+  --> $DIR/malformed-attrs.rs:192:1
    |
 LL | #[automatically_derived = 18]
    | ^^^^^^^^^^^^^^^^^^^^^^^^----^
@@ -614,7 +614,7 @@ LL | #[automatically_derived = 18]
    | help: must be of the form: `#[automatically_derived]`
 
 error[E0565]: malformed `non_exhaustive` attribute input
-  --> $DIR/malformed-attrs.rs:201:1
+  --> $DIR/malformed-attrs.rs:200:1
    |
 LL | #[non_exhaustive = 1]
    | ^^^^^^^^^^^^^^^^^---^
@@ -623,7 +623,7 @@ LL | #[non_exhaustive = 1]
    | help: must be of the form: `#[non_exhaustive]`
 
 error[E0565]: malformed `thread_local` attribute input
-  --> $DIR/malformed-attrs.rs:207:1
+  --> $DIR/malformed-attrs.rs:206:1
    |
 LL | #[thread_local()]
    | ^^^^^^^^^^^^^^--^
@@ -632,7 +632,7 @@ LL | #[thread_local()]
    | help: must be of the form: `#[thread_local]`
 
 error[E0565]: malformed `no_link` attribute input
-  --> $DIR/malformed-attrs.rs:211:1
+  --> $DIR/malformed-attrs.rs:210:1
    |
 LL | #[no_link()]
    | ^^^^^^^^^--^
@@ -641,7 +641,7 @@ LL | #[no_link()]
    | help: must be of the form: `#[no_link]`
 
 error[E0539]: malformed `macro_use` attribute input
-  --> $DIR/malformed-attrs.rs:213:1
+  --> $DIR/malformed-attrs.rs:212:1
    |
 LL | #[macro_use = 1]
    | ^^^^^^^^^^^^---^
@@ -659,7 +659,7 @@ LL + #[macro_use]
    |
 
 error[E0539]: malformed `macro_export` attribute input
-  --> $DIR/malformed-attrs.rs:218:1
+  --> $DIR/malformed-attrs.rs:217:1
    |
 LL | #[macro_export = 18]
    | ^^^^^^^^^^^^^^^----^
@@ -676,7 +676,7 @@ LL + #[macro_export]
    |
 
 error[E0565]: malformed `allow_internal_unsafe` attribute input
-  --> $DIR/malformed-attrs.rs:220:1
+  --> $DIR/malformed-attrs.rs:219:1
    |
 LL | #[allow_internal_unsafe = 1]
    | ^^^^^^^^^^^^^^^^^^^^^^^^---^
@@ -685,7 +685,7 @@ LL | #[allow_internal_unsafe = 1]
    | help: must be of the form: `#[allow_internal_unsafe]`
 
 error: attribute should be applied to `const fn`
-  --> $DIR/malformed-attrs.rs:32:1
+  --> $DIR/malformed-attrs.rs:31:1
    |
 LL |   #[rustc_allow_const_fn_unstable]
    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -697,7 +697,7 @@ LL | | }
    | |_- not a `const fn`
 
 warning: attribute should be applied to an `extern` block with non-Rust ABI
-  --> $DIR/malformed-attrs.rs:83:1
+  --> $DIR/malformed-attrs.rs:82:1
    |
 LL |   #[link]
    |   ^^^^^^^
@@ -712,19 +712,19 @@ LL | | }
    = note: requested on the command line with `-W unused-attributes`
 
 error: `#[repr(align(...))]` is not supported on functions
-  --> $DIR/malformed-attrs.rs:47:1
+  --> $DIR/malformed-attrs.rs:46:1
    |
 LL | #[repr]
    | ^^^^^^^
    |
 help: use `#[rustc_align(...)]` instead
-  --> $DIR/malformed-attrs.rs:47:1
+  --> $DIR/malformed-attrs.rs:46:1
    |
 LL | #[repr]
    | ^^^^^^^
 
 warning: missing options for `on_unimplemented` attribute
-  --> $DIR/malformed-attrs.rs:143:1
+  --> $DIR/malformed-attrs.rs:142:1
    |
 LL | #[diagnostic::on_unimplemented]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -733,7 +733,7 @@ LL | #[diagnostic::on_unimplemented]
    = note: `#[warn(malformed_diagnostic_attributes)]` (part of `#[warn(unknown_or_malformed_diagnostic_attributes)]`) on by default
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/malformed-attrs.rs:145:1
+  --> $DIR/malformed-attrs.rs:144:1
    |
 LL | #[diagnostic::on_unimplemented = 1]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -741,7 +741,7 @@ LL | #[diagnostic::on_unimplemented = 1]
    = help: only `message`, `note` and `label` are allowed as options
 
 error: valid forms for the attribute are `#[doc = "string"]`, `#[doc(alias)]`, `#[doc(attribute)]`, `#[doc(auto_cfg)]`, `#[doc(cfg)]`, `#[doc(fake_variadic)]`, `#[doc(hidden)]`, `#[doc(html_favicon_url)]`, `#[doc(html_logo_url)]`, `#[doc(html_no_source)]`, `#[doc(html_playground_url)]`, `#[doc(html_root_url)]`, `#[doc(include)]`, `#[doc(inline)]`, `#[doc(issue_tracker_base_url)]`, `#[doc(keyword)]`, `#[doc(masked)]`, `#[doc(no_default_passes)]`, `#[doc(no_inline)]`, `#[doc(notable_trait)]`, `#[doc(passes)]`, `#[doc(plugins)]`, `#[doc(rust_logo)]`, `#[doc(search_unbox)]`, `#[doc(spotlight)]`, and `#[doc(test)]`
-  --> $DIR/malformed-attrs.rs:42:1
+  --> $DIR/malformed-attrs.rs:41:1
    |
 LL | #[doc]
    | ^^^^^^
@@ -753,7 +753,7 @@ LL | #![deny(invalid_doc_attributes)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
 
 error: valid forms for the attribute are `#[inline(always)]`, `#[inline(never)]`, and `#[inline]`
-  --> $DIR/malformed-attrs.rs:52:1
+  --> $DIR/malformed-attrs.rs:51:1
    |
 LL | #[inline = 5]
    | ^^^^^^^^^^^^^
@@ -763,13 +763,13 @@ LL | #[inline = 5]
    = note: `#[deny(ill_formed_attribute_input)]` (part of `#[deny(future_incompatible)]`) on by default
 
 warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![crate_name]`
-  --> $DIR/malformed-attrs.rs:74:1
+  --> $DIR/malformed-attrs.rs:73:1
    |
 LL | #[crate_name]
    | ^^^^^^^^^^^^^
    |
 note: this attribute does not have an `!`, which means it is applied to this function
-  --> $DIR/malformed-attrs.rs:115:1
+  --> $DIR/malformed-attrs.rs:114:1
    |
 LL | / fn test() {
 LL | |     #[coroutine = 63] || {}
@@ -778,13 +778,13 @@ LL | | }
    | |_^
 
 error: valid forms for the attribute are `#[doc = "string"]`, `#[doc(alias)]`, `#[doc(attribute)]`, `#[doc(auto_cfg)]`, `#[doc(cfg)]`, `#[doc(fake_variadic)]`, `#[doc(hidden)]`, `#[doc(html_favicon_url)]`, `#[doc(html_logo_url)]`, `#[doc(html_no_source)]`, `#[doc(html_playground_url)]`, `#[doc(html_root_url)]`, `#[doc(include)]`, `#[doc(inline)]`, `#[doc(issue_tracker_base_url)]`, `#[doc(keyword)]`, `#[doc(masked)]`, `#[doc(no_default_passes)]`, `#[doc(no_inline)]`, `#[doc(notable_trait)]`, `#[doc(passes)]`, `#[doc(plugins)]`, `#[doc(rust_logo)]`, `#[doc(search_unbox)]`, `#[doc(spotlight)]`, and `#[doc(test)]`
-  --> $DIR/malformed-attrs.rs:77:1
+  --> $DIR/malformed-attrs.rs:76:1
    |
 LL | #[doc]
    | ^^^^^^
 
 warning: `#[link_name]` attribute cannot be used on functions
-  --> $DIR/malformed-attrs.rs:87:1
+  --> $DIR/malformed-attrs.rs:86:1
    |
 LL | #[link_name]
    | ^^^^^^^^^^^^
@@ -793,7 +793,7 @@ LL | #[link_name]
    = help: `#[link_name]` can be applied to foreign functions and foreign statics
 
 error: valid forms for the attribute are `#[ignore = "reason"]` and `#[ignore]`
-  --> $DIR/malformed-attrs.rs:97:1
+  --> $DIR/malformed-attrs.rs:96:1
    |
 LL | #[ignore()]
    | ^^^^^^^^^^^
@@ -802,7 +802,7 @@ LL | #[ignore()]
    = note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
 
 warning: `#[no_implicit_prelude]` attribute cannot be used on functions
-  --> $DIR/malformed-attrs.rs:100:1
+  --> $DIR/malformed-attrs.rs:99:1
    |
 LL | #[no_implicit_prelude = 23]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -811,13 +811,13 @@ LL | #[no_implicit_prelude = 23]
    = help: `#[no_implicit_prelude]` can be applied to crates and modules
 
 warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
-  --> $DIR/malformed-attrs.rs:152:1
+  --> $DIR/malformed-attrs.rs:151:1
    |
 LL | #[diagnostic::do_not_recommend()]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[automatically_derived]` attribute cannot be used on modules
-  --> $DIR/malformed-attrs.rs:193:1
+  --> $DIR/malformed-attrs.rs:192:1
    |
 LL | #[automatically_derived = 18]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -826,7 +826,7 @@ LL | #[automatically_derived = 18]
    = help: `#[automatically_derived]` can only be applied to trait impl blocks
 
 error: valid forms for the attribute are `#[ignore = "reason"]` and `#[ignore]`
-  --> $DIR/malformed-attrs.rs:227:1
+  --> $DIR/malformed-attrs.rs:226:1
    |
 LL | #[ignore = 1]
    | ^^^^^^^^^^^^^
@@ -835,7 +835,7 @@ LL | #[ignore = 1]
    = note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
 
 error[E0308]: mismatched types
-  --> $DIR/malformed-attrs.rs:116:23
+  --> $DIR/malformed-attrs.rs:115:23
    |
 LL | fn test() {
    |          - help: a return type might be missing here: `-> _`
@@ -843,7 +843,7 @@ LL |     #[coroutine = 63] || {}
    |                       ^^^^^ expected `()`, found coroutine
    |
    = note: expected unit type `()`
-              found coroutine `{coroutine@$DIR/malformed-attrs.rs:116:23: 116:25}`
+              found coroutine `{coroutine@$DIR/malformed-attrs.rs:115:23: 115:25}`
 
 error: aborting due to 75 previous errors; 8 warnings emitted
 
@@ -851,7 +851,7 @@ Some errors have detailed explanations: E0308, E0463, E0539, E0565, E0658, E0805
 For more information about an error, try `rustc --explain E0308`.
 Future incompatibility report: Future breakage diagnostic:
 error: valid forms for the attribute are `#[inline(always)]`, `#[inline(never)]`, and `#[inline]`
-  --> $DIR/malformed-attrs.rs:52:1
+  --> $DIR/malformed-attrs.rs:51:1
    |
 LL | #[inline = 5]
    | ^^^^^^^^^^^^^
@@ -862,7 +862,7 @@ LL | #[inline = 5]
 
 Future breakage diagnostic:
 error: valid forms for the attribute are `#[ignore = "reason"]` and `#[ignore]`
-  --> $DIR/malformed-attrs.rs:97:1
+  --> $DIR/malformed-attrs.rs:96:1
    |
 LL | #[ignore()]
    | ^^^^^^^^^^^
@@ -873,7 +873,7 @@ LL | #[ignore()]
 
 Future breakage diagnostic:
 error: valid forms for the attribute are `#[ignore = "reason"]` and `#[ignore]`
-  --> $DIR/malformed-attrs.rs:227:1
+  --> $DIR/malformed-attrs.rs:226:1
    |
 LL | #[ignore = 1]
    | ^^^^^^^^^^^^^
diff --git a/tests/ui/consts/precise-drop-allow-const-fn-unstable.rs b/tests/ui/consts/precise-drop-allow-const-fn-unstable.rs
index 56155e519dca4..4bd5f746f5021 100644
--- a/tests/ui/consts/precise-drop-allow-const-fn-unstable.rs
+++ b/tests/ui/consts/precise-drop-allow-const-fn-unstable.rs
@@ -2,7 +2,7 @@
 //@ compile-flags: --crate-type=lib -Cinstrument-coverage  -Zno-profiler-runtime
 //@[allow] check-pass
 
-#![feature(staged_api, rustc_allow_const_fn_unstable)]
+#![feature(staged_api, rustc_attrs)]
 #![stable(feature = "rust_test", since = "1.0.0")]
 
 #[stable(feature = "rust_test", since = "1.0.0")]
diff --git a/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.rs b/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.rs
index 19d8fa87f5536..0c0e0c3629361 100644
--- a/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.rs
+++ b/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.rs
@@ -1,6 +1,6 @@
 #![allow(unused_macros)]
 
-#[rustc_allow_const_fn_unstable()] //~ ERROR rustc_allow_const_fn_unstable side-steps
+#[rustc_allow_const_fn_unstable()] //~ ERROR use of an internal attribute
 const fn foo() { }
 
 fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.stderr b/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.stderr
index 44f7a4bb0e688..42424abcc3cb6 100644
--- a/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.stderr
+++ b/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.stderr
@@ -1,12 +1,12 @@
-error[E0658]: rustc_allow_const_fn_unstable side-steps feature gating and stability checks
+error[E0658]: use of an internal attribute
   --> $DIR/feature-gate-rustc-allow-const-fn-unstable.rs:3:1
    |
 LL | #[rustc_allow_const_fn_unstable()]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #69399 <https://github.com/rust-lang/rust/issues/69399> for more information
-   = help: add `#![feature(rustc_allow_const_fn_unstable)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+   = note: the `#[rustc_allow_const_fn_unstable]` attribute is an internal implementation detail that will never be stable
+   = note: rustc_allow_const_fn_unstable side-steps feature gating and stability checks
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/imports/overwrite-different-vis-3.rs b/tests/ui/imports/overwrite-different-vis-3.rs
new file mode 100644
index 0000000000000..f45c5cdfb3abf
--- /dev/null
+++ b/tests/ui/imports/overwrite-different-vis-3.rs
@@ -0,0 +1,14 @@
+// Regression test for issue #152606.
+
+//@ check-pass
+
+mod outer {
+    mod inner {
+        use super::*; // should go before the ambiguous glob imports
+    }
+
+    use crate::*;
+    pub use crate::*;
+}
+
+fn main() {}
diff --git a/tests/ui/lifetimes/mut-ref-owned-suggestion.rs b/tests/ui/lifetimes/mut-ref-owned-suggestion.rs
new file mode 100644
index 0000000000000..ae5e8f6658b63
--- /dev/null
+++ b/tests/ui/lifetimes/mut-ref-owned-suggestion.rs
@@ -0,0 +1,29 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/150077>
+//! Tests that `&mut T` suggests `T`, not `mut T`, `&mut str` suggests `String`, not `str`,
+//! when recommending an owned value.
+fn with_fn(_f: impl Fn() -> &mut ()) {}
+//~^ ERROR: missing lifetime specifier
+
+fn with_ref_mut_str(_f: impl Fn() -> &mut str) {}
+//~^ ERROR: missing lifetime specifier
+
+fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
+    //~^ ERROR: missing lifetime specifier
+    2
+}
+
+fn with_dyn(_f: Box<dyn Fn() -> &mut i32>) {}
+//~^ ERROR: missing lifetime specifier
+
+fn trait_bound<F: Fn() -> &mut i32>(_f: F) {}
+//~^ ERROR: missing lifetime specifier
+
+fn nested_result(_f: impl Fn() -> Result<&mut i32, ()>) {}
+//~^ ERROR: missing lifetime specifier
+
+struct Holder<F: Fn() -> &mut i32> {
+    //~^ ERROR: missing lifetime specifier
+    f: F,
+}
+
+fn main() {}
diff --git a/tests/ui/lifetimes/mut-ref-owned-suggestion.stderr b/tests/ui/lifetimes/mut-ref-owned-suggestion.stderr
new file mode 100644
index 0000000000000..a3e58331342a9
--- /dev/null
+++ b/tests/ui/lifetimes/mut-ref-owned-suggestion.stderr
@@ -0,0 +1,137 @@
+error[E0106]: missing lifetime specifier
+  --> $DIR/mut-ref-owned-suggestion.rs:4:29
+   |
+LL | fn with_fn(_f: impl Fn() -> &mut ()) {}
+   |                             ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
+help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
+   |
+LL | fn with_fn(_f: impl Fn() -> &'static mut ()) {}
+   |                              +++++++
+help: instead, you are more likely to want to return an owned value
+   |
+LL - fn with_fn(_f: impl Fn() -> &mut ()) {}
+LL + fn with_fn(_f: impl Fn() -> ()) {}
+   |
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/mut-ref-owned-suggestion.rs:7:38
+   |
+LL | fn with_ref_mut_str(_f: impl Fn() -> &mut str) {}
+   |                                      ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
+help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
+   |
+LL | fn with_ref_mut_str(_f: impl Fn() -> &'static mut str) {}
+   |                                       +++++++
+help: instead, you are more likely to want to return an owned value
+   |
+LL - fn with_ref_mut_str(_f: impl Fn() -> &mut str) {}
+LL + fn with_ref_mut_str(_f: impl Fn() -> String) {}
+   |
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/mut-ref-owned-suggestion.rs:10:40
+   |
+LL | fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
+   |                                        ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
+   = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
+help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
+   |
+LL | fn with_fn_has_return(_f: impl Fn() -> &'static mut ()) -> i32 {
+   |                                         +++++++
+help: consider making the bound lifetime-generic with a new `'a` lifetime
+   |
+LL - fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
+LL + fn with_fn_has_return(_f: impl for<'a> Fn() -> &'a ()) -> i32 {
+   |
+help: consider introducing a named lifetime parameter
+   |
+LL - fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
+LL + fn with_fn_has_return<'a>(_f: impl Fn() -> &'a ()) -> i32 {
+   |
+help: alternatively, you might want to return an owned value
+   |
+LL - fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
+LL + fn with_fn_has_return(_f: impl Fn() -> ()) -> i32 {
+   |
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/mut-ref-owned-suggestion.rs:15:33
+   |
+LL | fn with_dyn(_f: Box<dyn Fn() -> &mut i32>) {}
+   |                                 ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
+help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
+   |
+LL | fn with_dyn(_f: Box<dyn Fn() -> &'static mut i32>) {}
+   |                                  +++++++
+help: instead, you are more likely to want to return an owned value
+   |
+LL - fn with_dyn(_f: Box<dyn Fn() -> &mut i32>) {}
+LL + fn with_dyn(_f: Box<dyn Fn() -> i32>) {}
+   |
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/mut-ref-owned-suggestion.rs:18:27
+   |
+LL | fn trait_bound<F: Fn() -> &mut i32>(_f: F) {}
+   |                           ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
+help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
+   |
+LL | fn trait_bound<F: Fn() -> &'static mut i32>(_f: F) {}
+   |                            +++++++
+help: instead, you are more likely to want to change the argument to be borrowed...
+   |
+LL | fn trait_bound<F: Fn() -> &mut i32>(_f: &F) {}
+   |                                         +
+help: ...or alternatively, you might want to return an owned value
+   |
+LL - fn trait_bound<F: Fn() -> &mut i32>(_f: F) {}
+LL + fn trait_bound<F: Fn() -> i32>(_f: F) {}
+   |
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/mut-ref-owned-suggestion.rs:21:42
+   |
+LL | fn nested_result(_f: impl Fn() -> Result<&mut i32, ()>) {}
+   |                                          ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
+help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
+   |
+LL | fn nested_result(_f: impl Fn() -> Result<&'static mut i32, ()>) {}
+   |                                           +++++++
+help: instead, you are more likely to want to return an owned value
+   |
+LL - fn nested_result(_f: impl Fn() -> Result<&mut i32, ()>) {}
+LL + fn nested_result(_f: impl Fn() -> Result<i32, ()>) {}
+   |
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/mut-ref-owned-suggestion.rs:24:26
+   |
+LL | struct Holder<F: Fn() -> &mut i32> {
+   |                          ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
+help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
+   |
+LL | struct Holder<F: Fn() -> &'static mut i32> {
+   |                           +++++++
+help: instead, you are more likely to want to return an owned value
+   |
+LL - struct Holder<F: Fn() -> &mut i32> {
+LL + struct Holder<F: Fn() -> i32> {
+   |
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0106`.
diff --git a/tests/ui/proc-macro/pretty-print-hack-hide.rs b/tests/ui/proc-macro/pretty-print-hack-hide.rs
deleted file mode 100644
index fd98f16a780ea..0000000000000
--- a/tests/ui/proc-macro/pretty-print-hack-hide.rs
+++ /dev/null
@@ -1,12 +0,0 @@
-//@ proc-macro: test-macros.rs
-//@ compile-flags: -Z span-debug
-//@ check-pass
-
-#![no_std] // Don't load unnecessary hygiene information from std
-extern crate std;
-
-#[macro_use] extern crate test_macros;
-
-include!("pretty-print-hack/rental-0.5.6/src/lib.rs");
-
-fn main() {}
diff --git a/tests/ui/proc-macro/pretty-print-hack-hide.stdout b/tests/ui/proc-macro/pretty-print-hack-hide.stdout
deleted file mode 100644
index ea796bb269768..0000000000000
--- a/tests/ui/proc-macro/pretty-print-hack-hide.stdout
+++ /dev/null
@@ -1,21 +0,0 @@
-PRINT-DERIVE INPUT (DISPLAY): enum ProceduralMasqueradeDummyType { Input }
-PRINT-DERIVE INPUT (DEBUG): TokenStream [
-    Ident {
-        ident: "enum",
-        span: $DIR/pretty-print-hack/rental-0.5.6/src/lib.rs:4:1: 4:5 (#0),
-    },
-    Ident {
-        ident: "ProceduralMasqueradeDummyType",
-        span: $DIR/pretty-print-hack/rental-0.5.6/src/lib.rs:4:6: 4:35 (#0),
-    },
-    Group {
-        delimiter: Brace,
-        stream: TokenStream [
-            Ident {
-                ident: "Input",
-                span: $DIR/pretty-print-hack/rental-0.5.6/src/lib.rs:13:5: 13:10 (#0),
-            },
-        ],
-        span: $DIR/pretty-print-hack/rental-0.5.6/src/lib.rs:4:36: 14:2 (#0),
-    },
-]
diff --git a/tests/ui/proc-macro/pretty-print-hack-show.local.stderr b/tests/ui/proc-macro/pretty-print-hack-show.local.stderr
deleted file mode 100644
index 889cd0c90ebb2..0000000000000
--- a/tests/ui/proc-macro/pretty-print-hack-show.local.stderr
+++ /dev/null
@@ -1,6 +0,0 @@
-error: using an old version of `rental`
-   |
-   = note: older versions of the `rental` crate no longer compile; please update to `rental` v0.5.6, or switch to one of the `rental` alternatives
-
-error: aborting due to 1 previous error
-
diff --git a/tests/ui/proc-macro/pretty-print-hack-show.remapped.stderr b/tests/ui/proc-macro/pretty-print-hack-show.remapped.stderr
deleted file mode 100644
index 889cd0c90ebb2..0000000000000
--- a/tests/ui/proc-macro/pretty-print-hack-show.remapped.stderr
+++ /dev/null
@@ -1,6 +0,0 @@
-error: using an old version of `rental`
-   |
-   = note: older versions of the `rental` crate no longer compile; please update to `rental` v0.5.6, or switch to one of the `rental` alternatives
-
-error: aborting due to 1 previous error
-
diff --git a/tests/ui/proc-macro/pretty-print-hack-show.rs b/tests/ui/proc-macro/pretty-print-hack-show.rs
deleted file mode 100644
index 08e26c8114276..0000000000000
--- a/tests/ui/proc-macro/pretty-print-hack-show.rs
+++ /dev/null
@@ -1,21 +0,0 @@
-//@ proc-macro: test-macros.rs
-//@ compile-flags: -Z span-debug
-//@ revisions: local remapped
-//@ [remapped] remap-src-base
-
-#![no_std] // Don't load unnecessary hygiene information from std
-extern crate std;
-
-#[macro_use] extern crate test_macros;
-
-mod first {
-    include!("pretty-print-hack/allsorts-rental-0.5.6/src/lib.rs");
-}
-
-mod second {
-    include!("pretty-print-hack/rental-0.5.5/src/lib.rs");
-}
-
-fn main() {}
-
-//~? ERROR using an old version of `rental`
diff --git a/tests/ui/proc-macro/pretty-print-hack/allsorts-rental-0.5.6/src/lib.rs b/tests/ui/proc-macro/pretty-print-hack/allsorts-rental-0.5.6/src/lib.rs
deleted file mode 100644
index a27176a38e224..0000000000000
--- a/tests/ui/proc-macro/pretty-print-hack/allsorts-rental-0.5.6/src/lib.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-//@ ignore-auxiliary (used by `../../../pretty-print-hack-show.rs`)
-
-#[derive(Print)]
-enum ProceduralMasqueradeDummyType {
-//~^ ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-    Input
-}
diff --git a/tests/ui/proc-macro/pretty-print-hack/rental-0.5.5/src/lib.rs b/tests/ui/proc-macro/pretty-print-hack/rental-0.5.5/src/lib.rs
deleted file mode 100644
index a27176a38e224..0000000000000
--- a/tests/ui/proc-macro/pretty-print-hack/rental-0.5.5/src/lib.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-//@ ignore-auxiliary (used by `../../../pretty-print-hack-show.rs`)
-
-#[derive(Print)]
-enum ProceduralMasqueradeDummyType {
-//~^ ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-    Input
-}
diff --git a/tests/ui/proc-macro/pretty-print-hack/rental-0.5.6/src/lib.rs b/tests/ui/proc-macro/pretty-print-hack/rental-0.5.6/src/lib.rs
deleted file mode 100644
index 765ee4be656e3..0000000000000
--- a/tests/ui/proc-macro/pretty-print-hack/rental-0.5.6/src/lib.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-//@ ignore-auxiliary (used by `../../../pretty-print-hack/hide.rs`)
-
-#[derive(Print)]
-enum ProceduralMasqueradeDummyType {
-//~^ ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-//~| ERROR using
-//~| WARN this was previously
-    Input
-}
diff --git a/tests/ui/resolve/exported-macro-in-mod-147958.rs b/tests/ui/resolve/exported-macro-in-mod-147958.rs
new file mode 100644
index 0000000000000..5003c410b692d
--- /dev/null
+++ b/tests/ui/resolve/exported-macro-in-mod-147958.rs
@@ -0,0 +1,21 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/147958>
+
+//@ check-pass
+
+#![feature(decl_macro)]
+
+macro_rules! exported {
+    () => {
+        #[macro_export]
+        macro_rules! exported {
+            () => {};
+        }
+    };
+}
+use inner1::*;
+exported!();
+mod inner1 {
+    pub macro exported() {}
+}
+
+fn main() {}
diff --git a/tests/ui/traits/const-traits/staged-api.rs b/tests/ui/traits/const-traits/staged-api.rs
index 6d0a84797ea24..cd74bb45f651b 100644
--- a/tests/ui/traits/const-traits/staged-api.rs
+++ b/tests/ui/traits/const-traits/staged-api.rs
@@ -5,7 +5,7 @@
 #![feature(local_feature)]
 #![feature(const_trait_impl)]
 #![feature(staged_api)]
-#![feature(rustc_allow_const_fn_unstable)]
+#![feature(rustc_attrs)]
 #![stable(feature = "rust1", since = "1.0.0")]
 
 //@ aux-build: staged-api.rs