diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs
index 83b61ab17492c..bd2a5812cfad2 100644
--- a/compiler/rustc_const_eval/src/interpret/cast.rs
+++ b/compiler/rustc_const_eval/src/interpret/cast.rs
@@ -401,15 +401,46 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             }
             (ty::Dynamic(data_a, _, ty::Dyn), ty::Dynamic(data_b, _, ty::Dyn)) => {
                 let val = self.read_immediate(src)?;
-                if data_a.principal() == data_b.principal() {
-                    // A NOP cast that doesn't actually change anything, should be allowed even with mismatching vtables.
-                    // (But currently mismatching vtables violate the validity invariant so UB is triggered anyway.)
-                    return self.write_immediate(*val, dest);
-                }
+                // Take apart the old pointer, and find the dynamic type.
                 let (old_data, old_vptr) = val.to_scalar_pair();
                 let old_data = old_data.to_pointer(self)?;
                 let old_vptr = old_vptr.to_pointer(self)?;
                 let ty = self.get_ptr_vtable_ty(old_vptr, Some(data_a))?;
+
+                // Sanity-check that `supertrait_vtable_slot` in this type's vtable indeed produces
+                // our destination trait.
+                if cfg!(debug_assertions) {
+                    let vptr_entry_idx =
+                        self.tcx.supertrait_vtable_slot((src_pointee_ty, dest_pointee_ty));
+                    let vtable_entries = self.vtable_entries(data_a.principal(), ty);
+                    if let Some(entry_idx) = vptr_entry_idx {
+                        let Some(&ty::VtblEntry::TraitVPtr(upcast_trait_ref)) =
+                            vtable_entries.get(entry_idx)
+                        else {
+                            span_bug!(
+                                self.cur_span(),
+                                "invalid vtable entry index in {} -> {} upcast",
+                                src_pointee_ty,
+                                dest_pointee_ty
+                            );
+                        };
+                        let erased_trait_ref = upcast_trait_ref
+                            .map_bound(|r| ty::ExistentialTraitRef::erase_self_ty(*self.tcx, r));
+                        assert!(
+                            data_b
+                                .principal()
+                                .is_some_and(|b| self.eq_in_param_env(erased_trait_ref, b))
+                        );
+                    } else {
+                        // In this case codegen would keep using the old vtable. We don't want to do
+                        // that as it has the wrong trait. The reason codegen can do this is that
+                        // one vtable is a prefix of the other, so we double-check that.
+                        let vtable_entries_b = self.vtable_entries(data_b.principal(), ty);
+                        assert!(&vtable_entries[..vtable_entries_b.len()] == vtable_entries_b);
+                    };
+                }
+
+                // Get the destination trait vtable and return that.
                 let new_vptr = self.get_vtable_ptr(ty, data_b.principal())?;
                 self.write_immediate(Immediate::new_dyn_trait(old_data, new_vptr, self), dest)
             }
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 6d3e5ea103148..9fddeec2973a5 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -2,11 +2,15 @@ use std::cell::Cell;
 use std::{fmt, mem};
 
 use either::{Either, Left, Right};
+use rustc_infer::infer::at::ToTrace;
+use rustc_infer::traits::ObligationCause;
+use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::{debug, info, info_span, instrument, trace};
 
 use rustc_errors::DiagCtxtHandle;
 use rustc_hir::{self as hir, def_id::DefId, definitions::DefPathData};
 use rustc_index::IndexVec;
+use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{
     CtfeProvenance, ErrorHandled, InvalidMetaKind, ReportedErrorInfo,
@@ -640,6 +644,32 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         }
     }
 
+    /// Check if the two things are equal in the current param_env, using an infctx to get proper
+    /// equality checks.
+    pub(super) fn eq_in_param_env<T>(&self, a: T, b: T) -> bool
+    where
+        T: PartialEq + TypeFoldable<TyCtxt<'tcx>> + ToTrace<'tcx>,
+    {
+        // Fast path: compare directly.
+        if a == b {
+            return true;
+        }
+        // Slow path: spin up an inference context to check if these traits are sufficiently equal.
+        let infcx = self.tcx.infer_ctxt().build();
+        let ocx = ObligationCtxt::new(&infcx);
+        let cause = ObligationCause::dummy_with_span(self.cur_span());
+        // equate the two trait refs after normalization
+        let a = ocx.normalize(&cause, self.param_env, a);
+        let b = ocx.normalize(&cause, self.param_env, b);
+        if ocx.eq(&cause, self.param_env, a, b).is_ok() {
+            if ocx.select_all_or_error().is_empty() {
+                // All good.
+                return true;
+            }
+        }
+        return false;
+    }
+
     /// Walks up the callstack from the intrinsic's callsite, searching for the first callsite in a
     /// frame which is not `#[track_caller]`. This matches the `caller_location` intrinsic,
     /// and is primarily intended for the panic machinery.
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs
index 25f6bd640554e..56d3dc9410412 100644
--- a/compiler/rustc_const_eval/src/interpret/terminator.rs
+++ b/compiler/rustc_const_eval/src/interpret/terminator.rs
@@ -1,7 +1,6 @@
 use std::borrow::Cow;
 
 use either::Either;
-use rustc_middle::ty::TyCtxt;
 use tracing::trace;
 
 use rustc_middle::{
@@ -867,7 +866,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 };
 
                 // Obtain the underlying trait we are working on, and the adjusted receiver argument.
-                let (dyn_trait, dyn_ty, adjusted_recv) = if let ty::Dynamic(data, _, ty::DynStar) =
+                let (trait_, dyn_ty, adjusted_recv) = if let ty::Dynamic(data, _, ty::DynStar) =
                     receiver_place.layout.ty.kind()
                 {
                     let recv = self.unpack_dyn_star(&receiver_place, data)?;
@@ -898,20 +897,16 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                     (receiver_trait.principal(), dyn_ty, receiver_place.ptr())
                 };
 
-                // Now determine the actual method to call. We can do that in two different ways and
-                // compare them to ensure everything fits.
-                let vtable_entries = if let Some(dyn_trait) = dyn_trait {
-                    let trait_ref = dyn_trait.with_self_ty(*self.tcx, dyn_ty);
-                    let trait_ref = self.tcx.erase_regions(trait_ref);
-                    self.tcx.vtable_entries(trait_ref)
-                } else {
-                    TyCtxt::COMMON_VTABLE_ENTRIES
-                };
+                // Now determine the actual method to call. Usually we use the easy way of just
+                // looking up the method at index `idx`.
+                let vtable_entries = self.vtable_entries(trait_, dyn_ty);
                 let Some(ty::VtblEntry::Method(fn_inst)) = vtable_entries.get(idx).copied() else {
                     // FIXME(fee1-dead) these could be variants of the UB info enum instead of this
                     throw_ub_custom!(fluent::const_eval_dyn_call_not_a_method);
                 };
                 trace!("Virtual call dispatches to {fn_inst:#?}");
+                // We can also do the lookup based on `def_id` and `dyn_ty`, and check that that
+                // produces the same result.
                 if cfg!(debug_assertions) {
                     let tcx = *self.tcx;
 
diff --git a/compiler/rustc_const_eval/src/interpret/traits.rs b/compiler/rustc_const_eval/src/interpret/traits.rs
index bd2c651942185..fb50661b8263d 100644
--- a/compiler/rustc_const_eval/src/interpret/traits.rs
+++ b/compiler/rustc_const_eval/src/interpret/traits.rs
@@ -1,10 +1,7 @@
-use rustc_infer::infer::TyCtxtInferExt;
-use rustc_infer::traits::ObligationCause;
 use rustc_middle::mir::interpret::{InterpResult, Pointer};
 use rustc_middle::ty::layout::LayoutOf;
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, Ty, TyCtxt, VtblEntry};
 use rustc_target::abi::{Align, Size};
-use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::trace;
 
 use super::util::ensure_monomorphic_enough;
@@ -47,6 +44,20 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         Ok((layout.size, layout.align.abi))
     }
 
+    pub(super) fn vtable_entries(
+        &self,
+        trait_: Option<ty::PolyExistentialTraitRef<'tcx>>,
+        dyn_ty: Ty<'tcx>,
+    ) -> &'tcx [VtblEntry<'tcx>] {
+        if let Some(trait_) = trait_ {
+            let trait_ref = trait_.with_self_ty(*self.tcx, dyn_ty);
+            let trait_ref = self.tcx.erase_regions(trait_ref);
+            self.tcx.vtable_entries(trait_ref)
+        } else {
+            TyCtxt::COMMON_VTABLE_ENTRIES
+        }
+    }
+
     /// Check that the given vtable trait is valid for a pointer/reference/place with the given
     /// expected trait type.
     pub(super) fn check_vtable_for_type(
@@ -54,28 +65,15 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         vtable_trait: Option<ty::PolyExistentialTraitRef<'tcx>>,
         expected_trait: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
     ) -> InterpResult<'tcx> {
-        // Fast path: if they are equal, it's all fine.
-        if expected_trait.principal() == vtable_trait {
-            return Ok(());
-        }
-        if let (Some(expected_trait), Some(vtable_trait)) =
-            (expected_trait.principal(), vtable_trait)
-        {
-            // Slow path: spin up an inference context to check if these traits are sufficiently equal.
-            let infcx = self.tcx.infer_ctxt().build();
-            let ocx = ObligationCtxt::new(&infcx);
-            let cause = ObligationCause::dummy_with_span(self.cur_span());
-            // equate the two trait refs after normalization
-            let expected_trait = ocx.normalize(&cause, self.param_env, expected_trait);
-            let vtable_trait = ocx.normalize(&cause, self.param_env, vtable_trait);
-            if ocx.eq(&cause, self.param_env, expected_trait, vtable_trait).is_ok() {
-                if ocx.select_all_or_error().is_empty() {
-                    // All good.
-                    return Ok(());
-                }
-            }
+        let eq = match (expected_trait.principal(), vtable_trait) {
+            (Some(a), Some(b)) => self.eq_in_param_env(a, b),
+            (None, None) => true,
+            _ => false,
+        };
+        if !eq {
+            throw_ub!(InvalidVTableTrait { expected_trait, vtable_trait });
         }
-        throw_ub!(InvalidVTableTrait { expected_trait, vtable_trait });
+        Ok(())
     }
 
     /// Turn a place with a `dyn Trait` type into a place with the actual dynamic type.
diff --git a/compiler/rustc_trait_selection/src/traits/vtable.rs b/compiler/rustc_trait_selection/src/traits/vtable.rs
index 8f56f9c0f3eea..4645d8284612e 100644
--- a/compiler/rustc_trait_selection/src/traits/vtable.rs
+++ b/compiler/rustc_trait_selection/src/traits/vtable.rs
@@ -364,7 +364,9 @@ pub(crate) fn first_method_vtable_slot<'tcx>(tcx: TyCtxt<'tcx>, key: ty::TraitRe
 }
 
 /// Given a `dyn Subtrait` and `dyn Supertrait` trait object, find the slot of
-/// // the trait vptr in the subtrait's vtable.
+/// the trait vptr in the subtrait's vtable.
+///
+/// A return value of `None` means that the original vtable can be reused.
 pub(crate) fn supertrait_vtable_slot<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: (
@@ -373,20 +375,22 @@ pub(crate) fn supertrait_vtable_slot<'tcx>(
     ),
 ) -> Option<usize> {
     debug_assert!(!key.has_non_region_infer() && !key.has_non_region_param());
-
     let (source, target) = key;
-    let ty::Dynamic(source, _, _) = *source.kind() else {
+
+    // If the target principal is `None`, we can just return `None`.
+    let ty::Dynamic(target, _, _) = *target.kind() else {
         bug!();
     };
-    let source_principal = tcx
-        .normalize_erasing_regions(ty::ParamEnv::reveal_all(), source.principal().unwrap())
+    let target_principal = tcx
+        .normalize_erasing_regions(ty::ParamEnv::reveal_all(), target.principal()?)
         .with_self_ty(tcx, tcx.types.trait_object_dummy_self);
 
-    let ty::Dynamic(target, _, _) = *target.kind() else {
+    // Given that we have a target principal, it is a bug for there not to be a source principal.
+    let ty::Dynamic(source, _, _) = *source.kind() else {
         bug!();
     };
-    let target_principal = tcx
-        .normalize_erasing_regions(ty::ParamEnv::reveal_all(), target.principal().unwrap())
+    let source_principal = tcx
+        .normalize_erasing_regions(ty::ParamEnv::reveal_all(), source.principal().unwrap())
         .with_self_ty(tcx, tcx.types.trait_object_dummy_self);
 
     let vtable_segment_callback = {
diff --git a/src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.rs b/src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.rs
index 1d6b6777032de..85d7582d112ae 100644
--- a/src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.rs
+++ b/src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.rs
@@ -59,8 +59,10 @@ impl Baz for i32 {
 }
 
 fn main() {
-    let baz: &dyn Baz = &1;
-    let baz_fake: *const dyn Bar = unsafe { std::mem::transmute(baz) };
-    let _err = baz_fake as *const dyn Foo;
-    //~^ERROR: using vtable for trait `Baz` but trait `Bar` was expected
+    unsafe {
+        let baz: &dyn Baz = &1;
+        let baz_fake: *const dyn Bar = std::mem::transmute(baz);
+        let _err = baz_fake as *const dyn Foo;
+        //~^ERROR: using vtable for trait `Baz` but trait `Bar` was expected
+    }
 }
diff --git a/src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.stderr b/src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.stderr
index 6a2415cf57e29..87b1361c3e504 100644
--- a/src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.stderr
+++ b/src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.stderr
@@ -1,8 +1,8 @@
 error: Undefined Behavior: using vtable for trait `Baz` but trait `Bar` was expected
   --> $DIR/dyn-upcast-trait-mismatch.rs:LL:CC
    |
-LL |     let _err = baz_fake as *const dyn Foo;
-   |                ^^^^^^^^ using vtable for trait `Baz` but trait `Bar` was expected
+LL |         let _err = baz_fake as *const dyn Foo;
+   |                    ^^^^^^^^ using vtable for trait `Baz` but trait `Bar` was expected
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
diff --git a/tests/ui/consts/const-eval/raw-bytes.32bit.stderr b/tests/ui/consts/const-eval/raw-bytes.32bit.stderr
index c1748c2e23769..d7d24f373ebc1 100644
--- a/tests/ui/consts/const-eval/raw-bytes.32bit.stderr
+++ b/tests/ui/consts/const-eval/raw-bytes.32bit.stderr
@@ -436,30 +436,20 @@ LL | const TRAIT_OBJ_CONTENT_INVALID: &dyn Trait = unsafe { mem::transmute::<_,
                ╾ALLOC_ID╼ ╾ALLOC_ID╼                         │ ╾──╼╾──╼
            }
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:196:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/raw-bytes.rs:196:62
    |
 LL | const RAW_TRAIT_OBJ_VTABLE_NULL: *const dyn Trait = unsafe { mem::transmute((&92u8, 0usize)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered null pointer, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: 8, align: 4) {
-               ╾ALLOC_ID╼ 00 00 00 00                         │ ╾──╼....
-           }
+   |                                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:198:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/raw-bytes.rs:199:65
    |
 LL | const RAW_TRAIT_OBJ_VTABLE_INVALID: *const dyn Trait = unsafe { mem::transmute((&92u8, &3u64)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC27<imm>, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: 8, align: 4) {
-               ╾ALLOC_ID╼ ╾ALLOC_ID╼                         │ ╾──╼╾──╼
-           }
+   |                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC32 as vtable pointer but it does not point to a vtable
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:202:1
+  --> $DIR/raw-bytes.rs:204:1
    |
 LL | const _: &[!; 1] = unsafe { &*(1_usize as *const [!; 1]) };
    | ^^^^^^^^^^^^^^^^ constructing invalid value: encountered a reference pointing to uninhabited type [!; 1]
@@ -470,7 +460,7 @@ LL | const _: &[!; 1] = unsafe { &*(1_usize as *const [!; 1]) };
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:203:1
+  --> $DIR/raw-bytes.rs:205:1
    |
 LL | const _: &[!] = unsafe { &*(1_usize as *const [!; 1]) };
    | ^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered a value of the never type `!`
@@ -481,7 +471,7 @@ LL | const _: &[!] = unsafe { &*(1_usize as *const [!; 1]) };
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:204:1
+  --> $DIR/raw-bytes.rs:206:1
    |
 LL | const _: &[!] = unsafe { &*(1_usize as *const [!; 42]) };
    | ^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered a value of the never type `!`
@@ -492,7 +482,7 @@ LL | const _: &[!] = unsafe { &*(1_usize as *const [!; 42]) };
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:208:1
+  --> $DIR/raw-bytes.rs:210:1
    |
 LL | pub static S4: &[u8] = unsafe { from_raw_parts((&D1) as *const _ as _, 1) };
    | ^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered uninitialized memory, but expected an integer
@@ -503,7 +493,7 @@ LL | pub static S4: &[u8] = unsafe { from_raw_parts((&D1) as *const _ as _, 1) }
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:211:1
+  --> $DIR/raw-bytes.rs:213:1
    |
 LL | pub static S5: &[u8] = unsafe { from_raw_parts((&D3) as *const _ as _, mem::size_of::<&u32>()) };
    | ^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered a pointer, but expected an integer
@@ -516,7 +506,7 @@ LL | pub static S5: &[u8] = unsafe { from_raw_parts((&D3) as *const _ as _, mem:
    = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:214:1
+  --> $DIR/raw-bytes.rs:216:1
    |
 LL | pub static S6: &[bool] = unsafe { from_raw_parts((&D0) as *const _ as _, 4) };
    | ^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered 0x11, but expected a boolean
@@ -527,7 +517,7 @@ LL | pub static S6: &[bool] = unsafe { from_raw_parts((&D0) as *const _ as _, 4)
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:218:1
+  --> $DIR/raw-bytes.rs:220:1
    |
 LL | pub static S7: &[u16] = unsafe {
    | ^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[1]: encountered uninitialized memory, but expected an integer
@@ -538,7 +528,7 @@ LL | pub static S7: &[u16] = unsafe {
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:225:1
+  --> $DIR/raw-bytes.rs:227:1
    |
 LL | pub static R4: &[u8] = unsafe {
    | ^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered uninitialized memory, but expected an integer
@@ -549,7 +539,7 @@ LL | pub static R4: &[u8] = unsafe {
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:230:1
+  --> $DIR/raw-bytes.rs:232:1
    |
 LL | pub static R5: &[u8] = unsafe {
    | ^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered a pointer, but expected an integer
@@ -562,7 +552,7 @@ LL | pub static R5: &[u8] = unsafe {
    = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:235:1
+  --> $DIR/raw-bytes.rs:237:1
    |
 LL | pub static R6: &[bool] = unsafe {
    | ^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered 0x11, but expected a boolean
diff --git a/tests/ui/consts/const-eval/raw-bytes.64bit.stderr b/tests/ui/consts/const-eval/raw-bytes.64bit.stderr
index eb97eab9db756..22679acda98b8 100644
--- a/tests/ui/consts/const-eval/raw-bytes.64bit.stderr
+++ b/tests/ui/consts/const-eval/raw-bytes.64bit.stderr
@@ -436,30 +436,20 @@ LL | const TRAIT_OBJ_CONTENT_INVALID: &dyn Trait = unsafe { mem::transmute::<_,
                ╾ALLOC_ID╼ ╾ALLOC_ID╼ │ ╾──────╼╾──────╼
            }
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:196:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/raw-bytes.rs:196:62
    |
 LL | const RAW_TRAIT_OBJ_VTABLE_NULL: *const dyn Trait = unsafe { mem::transmute((&92u8, 0usize)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered null pointer, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: 16, align: 8) {
-               ╾ALLOC_ID╼ 00 00 00 00 00 00 00 00 │ ╾──────╼........
-           }
+   |                                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:198:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/raw-bytes.rs:199:65
    |
 LL | const RAW_TRAIT_OBJ_VTABLE_INVALID: *const dyn Trait = unsafe { mem::transmute((&92u8, &3u64)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC27<imm>, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: 16, align: 8) {
-               ╾ALLOC_ID╼ ╾ALLOC_ID╼ │ ╾──────╼╾──────╼
-           }
+   |                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC32 as vtable pointer but it does not point to a vtable
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:202:1
+  --> $DIR/raw-bytes.rs:204:1
    |
 LL | const _: &[!; 1] = unsafe { &*(1_usize as *const [!; 1]) };
    | ^^^^^^^^^^^^^^^^ constructing invalid value: encountered a reference pointing to uninhabited type [!; 1]
@@ -470,7 +460,7 @@ LL | const _: &[!; 1] = unsafe { &*(1_usize as *const [!; 1]) };
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:203:1
+  --> $DIR/raw-bytes.rs:205:1
    |
 LL | const _: &[!] = unsafe { &*(1_usize as *const [!; 1]) };
    | ^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered a value of the never type `!`
@@ -481,7 +471,7 @@ LL | const _: &[!] = unsafe { &*(1_usize as *const [!; 1]) };
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:204:1
+  --> $DIR/raw-bytes.rs:206:1
    |
 LL | const _: &[!] = unsafe { &*(1_usize as *const [!; 42]) };
    | ^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered a value of the never type `!`
@@ -492,7 +482,7 @@ LL | const _: &[!] = unsafe { &*(1_usize as *const [!; 42]) };
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:208:1
+  --> $DIR/raw-bytes.rs:210:1
    |
 LL | pub static S4: &[u8] = unsafe { from_raw_parts((&D1) as *const _ as _, 1) };
    | ^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered uninitialized memory, but expected an integer
@@ -503,7 +493,7 @@ LL | pub static S4: &[u8] = unsafe { from_raw_parts((&D1) as *const _ as _, 1) }
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:211:1
+  --> $DIR/raw-bytes.rs:213:1
    |
 LL | pub static S5: &[u8] = unsafe { from_raw_parts((&D3) as *const _ as _, mem::size_of::<&u32>()) };
    | ^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered a pointer, but expected an integer
@@ -516,7 +506,7 @@ LL | pub static S5: &[u8] = unsafe { from_raw_parts((&D3) as *const _ as _, mem:
    = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:214:1
+  --> $DIR/raw-bytes.rs:216:1
    |
 LL | pub static S6: &[bool] = unsafe { from_raw_parts((&D0) as *const _ as _, 4) };
    | ^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered 0x11, but expected a boolean
@@ -527,7 +517,7 @@ LL | pub static S6: &[bool] = unsafe { from_raw_parts((&D0) as *const _ as _, 4)
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:218:1
+  --> $DIR/raw-bytes.rs:220:1
    |
 LL | pub static S7: &[u16] = unsafe {
    | ^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[1]: encountered uninitialized memory, but expected an integer
@@ -538,7 +528,7 @@ LL | pub static S7: &[u16] = unsafe {
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:225:1
+  --> $DIR/raw-bytes.rs:227:1
    |
 LL | pub static R4: &[u8] = unsafe {
    | ^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered uninitialized memory, but expected an integer
@@ -549,7 +539,7 @@ LL | pub static R4: &[u8] = unsafe {
            }
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:230:1
+  --> $DIR/raw-bytes.rs:232:1
    |
 LL | pub static R5: &[u8] = unsafe {
    | ^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered a pointer, but expected an integer
@@ -562,7 +552,7 @@ LL | pub static R5: &[u8] = unsafe {
    = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/raw-bytes.rs:235:1
+  --> $DIR/raw-bytes.rs:237:1
    |
 LL | pub static R6: &[bool] = unsafe {
    | ^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered 0x11, but expected a boolean
diff --git a/tests/ui/consts/const-eval/raw-bytes.rs b/tests/ui/consts/const-eval/raw-bytes.rs
index 1c7ef6f2b0f8e..de1a81b00243b 100644
--- a/tests/ui/consts/const-eval/raw-bytes.rs
+++ b/tests/ui/consts/const-eval/raw-bytes.rs
@@ -194,9 +194,11 @@ const TRAIT_OBJ_CONTENT_INVALID: &dyn Trait = unsafe { mem::transmute::<_, &bool
 //~| expected a boolean
 
 const RAW_TRAIT_OBJ_VTABLE_NULL: *const dyn Trait = unsafe { mem::transmute((&92u8, 0usize)) };
-//~^ ERROR it is undefined behavior to use this value
+//~^ ERROR evaluation of constant value failed
+//~| null pointer
 const RAW_TRAIT_OBJ_VTABLE_INVALID: *const dyn Trait = unsafe { mem::transmute((&92u8, &3u64)) };
-//~^ ERROR it is undefined behavior to use this value
+//~^ ERROR evaluation of constant value failed
+//~| vtable
 
 // Uninhabited types
 const _: &[!; 1] = unsafe { &*(1_usize as *const [!; 1]) }; //~ ERROR undefined behavior
diff --git a/tests/ui/consts/const-eval/ub-incorrect-vtable.32bit.stderr b/tests/ui/consts/const-eval/ub-incorrect-vtable.32bit.stderr
index 5c47cbfdf3b1e..439ccb24e6167 100644
--- a/tests/ui/consts/const-eval/ub-incorrect-vtable.32bit.stderr
+++ b/tests/ui/consts/const-eval/ub-incorrect-vtable.32bit.stderr
@@ -1,56 +1,46 @@
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-incorrect-vtable.rs:18:1
-   |
-LL | const INVALID_VTABLE_ALIGNMENT: &dyn Trait =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC1<imm>, but expected a vtable pointer
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-incorrect-vtable.rs:19:14
    |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: 8, align: 4) {
-               ╾ALLOC0<imm>╼ ╾ALLOC1<imm>╼                         │ ╾──╼╾──╼
-           }
+LL |     unsafe { std::mem::transmute((&92u8, &[0usize, 1usize, 1000usize])) };
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC8 as vtable pointer but it does not point to a vtable
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-incorrect-vtable.rs:23:1
-   |
-LL | const INVALID_VTABLE_SIZE: &dyn Trait =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC3<imm>, but expected a vtable pointer
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-incorrect-vtable.rs:24:14
    |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: 8, align: 4) {
-               ╾ALLOC2<imm>╼ ╾ALLOC3<imm>╼                         │ ╾──╼╾──╼
-           }
+LL |     unsafe { std::mem::transmute((&92u8, &[1usize, usize::MAX, 1usize])) };
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC9 as vtable pointer but it does not point to a vtable
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-incorrect-vtable.rs:33:1
    |
 LL | const INVALID_VTABLE_ALIGNMENT_UB: W<&dyn Trait> =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC5<imm>, but expected a vtable pointer
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC1<imm>, but expected a vtable pointer
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: 8, align: 4) {
-               ╾ALLOC4<imm>╼ ╾ALLOC5<imm>╼                         │ ╾──╼╾──╼
+               ╾ALLOC0<imm>╼ ╾ALLOC1<imm>╼                         │ ╾──╼╾──╼
            }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-incorrect-vtable.rs:38:1
    |
 LL | const INVALID_VTABLE_SIZE_UB: W<&dyn Trait> =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC7<imm>, but expected a vtable pointer
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC3<imm>, but expected a vtable pointer
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: 8, align: 4) {
-               ╾ALLOC6<imm>╼ ╾ALLOC7<imm>╼                         │ ╾──╼╾──╼
+               ╾ALLOC2<imm>╼ ╾ALLOC3<imm>╼                         │ ╾──╼╾──╼
            }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-incorrect-vtable.rs:44:1
    |
 LL | const INVALID_VTABLE_UB: W<&dyn Trait> =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC9<imm>, but expected a vtable pointer
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC5<imm>, but expected a vtable pointer
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: 8, align: 4) {
-               ╾ALLOC8<imm>╼ ╾ALLOC9<imm>╼                         │ ╾──╼╾──╼
+               ╾ALLOC4<imm>╼ ╾ALLOC5<imm>╼                         │ ╾──╼╾──╼
            }
 
 error[E0080]: it is undefined behavior to use this value
@@ -61,7 +51,7 @@ LL | const G: Wide = unsafe { Transmute { t: FOO }.u };
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: 8, align: 4) {
-               ╾ALLOC10<imm>╼ ╾ALLOC11╼                         │ ╾──╼╾──╼
+               ╾ALLOC6<imm>╼ ╾ALLOC7╼                         │ ╾──╼╾──╼
            }
 
 error: aborting due to 6 previous errors
diff --git a/tests/ui/consts/const-eval/ub-incorrect-vtable.64bit.stderr b/tests/ui/consts/const-eval/ub-incorrect-vtable.64bit.stderr
index f400073aca215..89bf959703a04 100644
--- a/tests/ui/consts/const-eval/ub-incorrect-vtable.64bit.stderr
+++ b/tests/ui/consts/const-eval/ub-incorrect-vtable.64bit.stderr
@@ -1,56 +1,46 @@
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-incorrect-vtable.rs:18:1
-   |
-LL | const INVALID_VTABLE_ALIGNMENT: &dyn Trait =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC1<imm>, but expected a vtable pointer
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-incorrect-vtable.rs:19:14
    |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: 16, align: 8) {
-               ╾ALLOC0<imm>╼ ╾ALLOC1<imm>╼ │ ╾──────╼╾──────╼
-           }
+LL |     unsafe { std::mem::transmute((&92u8, &[0usize, 1usize, 1000usize])) };
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC8 as vtable pointer but it does not point to a vtable
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-incorrect-vtable.rs:23:1
-   |
-LL | const INVALID_VTABLE_SIZE: &dyn Trait =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC3<imm>, but expected a vtable pointer
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-incorrect-vtable.rs:24:14
    |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: 16, align: 8) {
-               ╾ALLOC2<imm>╼ ╾ALLOC3<imm>╼ │ ╾──────╼╾──────╼
-           }
+LL |     unsafe { std::mem::transmute((&92u8, &[1usize, usize::MAX, 1usize])) };
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC9 as vtable pointer but it does not point to a vtable
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-incorrect-vtable.rs:33:1
    |
 LL | const INVALID_VTABLE_ALIGNMENT_UB: W<&dyn Trait> =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC5<imm>, but expected a vtable pointer
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC1<imm>, but expected a vtable pointer
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: 16, align: 8) {
-               ╾ALLOC4<imm>╼ ╾ALLOC5<imm>╼ │ ╾──────╼╾──────╼
+               ╾ALLOC0<imm>╼ ╾ALLOC1<imm>╼ │ ╾──────╼╾──────╼
            }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-incorrect-vtable.rs:38:1
    |
 LL | const INVALID_VTABLE_SIZE_UB: W<&dyn Trait> =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC7<imm>, but expected a vtable pointer
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC3<imm>, but expected a vtable pointer
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: 16, align: 8) {
-               ╾ALLOC6<imm>╼ ╾ALLOC7<imm>╼ │ ╾──────╼╾──────╼
+               ╾ALLOC2<imm>╼ ╾ALLOC3<imm>╼ │ ╾──────╼╾──────╼
            }
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-incorrect-vtable.rs:44:1
    |
 LL | const INVALID_VTABLE_UB: W<&dyn Trait> =
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC9<imm>, but expected a vtable pointer
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC5<imm>, but expected a vtable pointer
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: 16, align: 8) {
-               ╾ALLOC8<imm>╼ ╾ALLOC9<imm>╼ │ ╾──────╼╾──────╼
+               ╾ALLOC4<imm>╼ ╾ALLOC5<imm>╼ │ ╾──────╼╾──────╼
            }
 
 error[E0080]: it is undefined behavior to use this value
@@ -61,7 +51,7 @@ LL | const G: Wide = unsafe { Transmute { t: FOO }.u };
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: 16, align: 8) {
-               ╾ALLOC10<imm>╼ ╾ALLOC11╼ │ ╾──────╼╾──────╼
+               ╾ALLOC6<imm>╼ ╾ALLOC7╼ │ ╾──────╼╾──────╼
            }
 
 error: aborting due to 6 previous errors
diff --git a/tests/ui/consts/const-eval/ub-incorrect-vtable.rs b/tests/ui/consts/const-eval/ub-incorrect-vtable.rs
index 11c3b2fe5603d..4325495a3801b 100644
--- a/tests/ui/consts/const-eval/ub-incorrect-vtable.rs
+++ b/tests/ui/consts/const-eval/ub-incorrect-vtable.rs
@@ -17,13 +17,13 @@ trait Trait {}
 
 const INVALID_VTABLE_ALIGNMENT: &dyn Trait =
     unsafe { std::mem::transmute((&92u8, &[0usize, 1usize, 1000usize])) };
-//~^^ ERROR it is undefined behavior to use this value
-//~| expected a vtable pointer
+//~^ ERROR evaluation of constant value failed
+//~| vtable
 
 const INVALID_VTABLE_SIZE: &dyn Trait =
     unsafe { std::mem::transmute((&92u8, &[1usize, usize::MAX, 1usize])) };
-//~^^ ERROR it is undefined behavior to use this value
-//~| expected a vtable pointer
+//~^ ERROR evaluation of constant value failed
+//~| vtable
 
 #[repr(transparent)]
 struct W<T>(T);
diff --git a/tests/ui/consts/const-eval/ub-wide-ptr.rs b/tests/ui/consts/const-eval/ub-wide-ptr.rs
index d0d93081738fe..3956146f6aef2 100644
--- a/tests/ui/consts/const-eval/ub-wide-ptr.rs
+++ b/tests/ui/consts/const-eval/ub-wide-ptr.rs
@@ -113,27 +113,27 @@ const RAW_SLICE_LENGTH_UNINIT: *const [u8] = unsafe {
 // bad trait object
 const TRAIT_OBJ_SHORT_VTABLE_1: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, &3u8))) };
 //~^ ERROR it is undefined behavior to use this value
-//~| expected a vtable
+//~| vtable
 // bad trait object
 const TRAIT_OBJ_SHORT_VTABLE_2: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, &3u64))) };
 //~^ ERROR it is undefined behavior to use this value
-//~| expected a vtable
+//~| vtable
 // bad trait object
 const TRAIT_OBJ_INT_VTABLE: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, 4usize))) };
 //~^ ERROR it is undefined behavior to use this value
-//~| expected a vtable
+//~| vtable
 const TRAIT_OBJ_UNALIGNED_VTABLE: &dyn Trait = unsafe { mem::transmute((&92u8, &[0u8; 128])) };
-//~^ ERROR it is undefined behavior to use this value
-//~| expected a vtable
+//~^ ERROR evaluation of constant value failed
+//~| vtable
 const TRAIT_OBJ_BAD_DROP_FN_NULL: &dyn Trait = unsafe { mem::transmute((&92u8, &[0usize; 8])) };
-//~^ ERROR it is undefined behavior to use this value
-//~| expected a vtable
+//~^ ERROR evaluation of constant value failed
+//~| vtable
 const TRAIT_OBJ_BAD_DROP_FN_INT: &dyn Trait = unsafe { mem::transmute((&92u8, &[1usize; 8])) };
-//~^ ERROR it is undefined behavior to use this value
-//~| expected a vtable
+//~^ ERROR evaluation of constant value failed
+//~| vtable
 const TRAIT_OBJ_BAD_DROP_FN_NOT_FN_PTR: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, &[&42u8; 8]))) };
 //~^ ERROR it is undefined behavior to use this value
-//~| expected a vtable
+//~| vtable
 
 // bad data *inside* the trait object
 const TRAIT_OBJ_CONTENT_INVALID: &dyn Trait = unsafe { mem::transmute::<_, &bool>(&3u8) };
@@ -142,21 +142,25 @@ const TRAIT_OBJ_CONTENT_INVALID: &dyn Trait = unsafe { mem::transmute::<_, &bool
 
 // # raw trait object
 const RAW_TRAIT_OBJ_VTABLE_NULL: *const dyn Trait = unsafe { mem::transmute((&92u8, 0usize)) };
-//~^ ERROR it is undefined behavior to use this value
+//~^ ERROR evaluation of constant value failed
+//~| null pointer
 const RAW_TRAIT_OBJ_VTABLE_INVALID: *const dyn Trait = unsafe { mem::transmute((&92u8, &3u64)) };
-//~^ ERROR it is undefined behavior to use this value
+//~^ ERROR evaluation of constant value failed
+//~| vtable
 const RAW_TRAIT_OBJ_CONTENT_INVALID: *const dyn Trait = unsafe { mem::transmute::<_, &bool>(&3u8) } as *const dyn Trait; // ok because raw
 // Officially blessed way to get the vtable
 const DYN_METADATA: ptr::DynMetadata<dyn Send> = ptr::metadata::<dyn Send>(ptr::null::<i32>());
 
-// Const eval fails for these, so they need to be statics to error.
+
 static mut RAW_TRAIT_OBJ_VTABLE_NULL_THROUGH_REF: *const dyn Trait = unsafe {
-//~^ ERROR it is undefined behavior to use this value
     mem::transmute::<_, &dyn Trait>((&92u8, 0usize))
+    //~^ ERROR could not evaluate static initializer
+    //~| null pointer
 };
 static mut RAW_TRAIT_OBJ_VTABLE_INVALID_THROUGH_REF: *const dyn Trait = unsafe {
-//~^ ERROR it is undefined behavior to use this value
     mem::transmute::<_, &dyn Trait>((&92u8, &3u64))
+    //~^ ERROR could not evaluate static initializer
+    //~| vtable
 };
 
 fn main() {}
diff --git a/tests/ui/consts/const-eval/ub-wide-ptr.stderr b/tests/ui/consts/const-eval/ub-wide-ptr.stderr
index 2fa462a6a648c..4fe744265dfb3 100644
--- a/tests/ui/consts/const-eval/ub-wide-ptr.stderr
+++ b/tests/ui/consts/const-eval/ub-wide-ptr.stderr
@@ -218,44 +218,29 @@ LL | const TRAIT_OBJ_INT_VTABLE: W<&dyn Trait> = unsafe { mem::transmute(W((&92u
                HEX_DUMP
            }
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-wide-ptr.rs:125:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-wide-ptr.rs:125:57
    |
 LL | const TRAIT_OBJ_UNALIGNED_VTABLE: &dyn Trait = unsafe { mem::transmute((&92u8, &[0u8; 128])) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC17<imm>, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
-               HEX_DUMP
-           }
+   |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC20 as vtable pointer but it does not point to a vtable
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-wide-ptr.rs:128:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-wide-ptr.rs:128:57
    |
 LL | const TRAIT_OBJ_BAD_DROP_FN_NULL: &dyn Trait = unsafe { mem::transmute((&92u8, &[0usize; 8])) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC19<imm>, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
-               HEX_DUMP
-           }
+   |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC21 as vtable pointer but it does not point to a vtable
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-wide-ptr.rs:131:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-wide-ptr.rs:131:56
    |
 LL | const TRAIT_OBJ_BAD_DROP_FN_INT: &dyn Trait = unsafe { mem::transmute((&92u8, &[1usize; 8])) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC21<imm>, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
-               HEX_DUMP
-           }
+   |                                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC22 as vtable pointer but it does not point to a vtable
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-wide-ptr.rs:134:1
    |
 LL | const TRAIT_OBJ_BAD_DROP_FN_NOT_FN_PTR: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, &[&42u8; 8]))) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC23<imm>, but expected a vtable pointer
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered ALLOC17<imm>, but expected a vtable pointer
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
    = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
@@ -273,49 +258,29 @@ LL | const TRAIT_OBJ_CONTENT_INVALID: &dyn Trait = unsafe { mem::transmute::<_,
                HEX_DUMP
            }
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-wide-ptr.rs:144:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-wide-ptr.rs:144:62
    |
 LL | const RAW_TRAIT_OBJ_VTABLE_NULL: *const dyn Trait = unsafe { mem::transmute((&92u8, 0usize)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered null pointer, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
-               HEX_DUMP
-           }
+   |                                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-wide-ptr.rs:146:1
+error[E0080]: evaluation of constant value failed
+  --> $DIR/ub-wide-ptr.rs:147:65
    |
 LL | const RAW_TRAIT_OBJ_VTABLE_INVALID: *const dyn Trait = unsafe { mem::transmute((&92u8, &3u64)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC28<imm>, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
-               HEX_DUMP
-           }
+   |                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC23 as vtable pointer but it does not point to a vtable
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-wide-ptr.rs:153:1
+error[E0080]: could not evaluate static initializer
+  --> $DIR/ub-wide-ptr.rs:156:5
    |
-LL | static mut RAW_TRAIT_OBJ_VTABLE_NULL_THROUGH_REF: *const dyn Trait = unsafe {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered null pointer, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
-               HEX_DUMP
-           }
+LL |     mem::transmute::<_, &dyn Trait>((&92u8, 0usize))
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-wide-ptr.rs:157:1
+error[E0080]: could not evaluate static initializer
+  --> $DIR/ub-wide-ptr.rs:161:5
    |
-LL | static mut RAW_TRAIT_OBJ_VTABLE_INVALID_THROUGH_REF: *const dyn Trait = unsafe {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered ALLOC31<imm>, but expected a vtable pointer
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
-   = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
-               HEX_DUMP
-           }
+LL |     mem::transmute::<_, &dyn Trait>((&92u8, &3u64))
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using ALLOC24 as vtable pointer but it does not point to a vtable
 
 error: aborting due to 29 previous errors