Use translatable diagnostics in `rustc_const_eval`

7 files changed, 260 insertions, 228 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs
index 163e3f86993..b4db3dff3ff 100644
--- a/compiler/rustc_const_eval/src/interpret/cast.rs
+++ b/compiler/rustc_const_eval/src/interpret/cast.rs
@@ -14,6 +14,8 @@ use super::{
     util::ensure_monomorphic_enough, FnVal, ImmTy, Immediate, InterpCx, Machine, OpTy, PlaceTy,
 };
 
+use crate::fluent_generated as fluent;
+
 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     pub fn cast(
         &mut self,
@@ -138,12 +140,16 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 assert!(src.layout.is_sized());
                 assert!(dest.layout.is_sized());
                 if src.layout.size != dest.layout.size {
-                    throw_ub_format!(
-                        "transmuting from {}-byte type to {}-byte type: `{}` -> `{}`",
-                        src.layout.size.bytes(),
-                        dest.layout.size.bytes(),
-                        src.layout.ty,
-                        dest.layout.ty,
+                    let src_bytes = src.layout.size.bytes();
+                    let dest_bytes = dest.layout.size.bytes();
+                    let src_ty = format!("{}", src.layout.ty);
+                    let dest_ty = format!("{}", dest.layout.ty);
+                    throw_ub_custom!(
+                        fluent::const_eval_invalid_transmute,
+                        src_bytes = src_bytes,
+                        dest_bytes = dest_bytes,
+                        src = src_ty,
+                        dest = dest_ty,
                     );
                 }
 
@@ -363,7 +369,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let old_vptr = old_vptr.to_pointer(self)?;
                 let (ty, old_trait) = self.get_ptr_vtable(old_vptr)?;
                 if old_trait != data_a.principal() {
-                    throw_ub_format!("upcast on a pointer whose vtable does not match its type");
+                    throw_ub_custom!(fluent::const_eval_upcast_mismatch);
                 }
                 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 cd43a53b1b3..36606ff69a6 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -1,6 +1,5 @@
 use std::cell::Cell;
-use std::fmt;
-use std::mem;
+use std::{fmt, mem};
 
 use either::{Either, Left, Right};
 
@@ -8,7 +7,7 @@ use hir::CRATE_HIR_ID;
 use rustc_hir::{self as hir, def_id::DefId, definitions::DefPathData};
 use rustc_index::IndexVec;
 use rustc_middle::mir;
-use rustc_middle::mir::interpret::{ErrorHandled, InterpError, ReportedErrorInfo};
+use rustc_middle::mir::interpret::{ErrorHandled, InterpError, InvalidMetaKind, ReportedErrorInfo};
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::layout::{
     self, FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOf, LayoutOfHelpers,
@@ -25,6 +24,8 @@ use super::{
     MemPlaceMeta, Memory, MemoryKind, Operand, Place, PlaceTy, PointerArithmetic, Provenance,
     Scalar, StackPopJump,
 };
+use crate::errors::{self, ErroneousConstUsed};
+use crate::fluent_generated as fluent;
 use crate::util;
 
 pub struct InterpCx<'mir, 'tcx, M: Machine<'mir, 'tcx>> {
@@ -247,6 +248,7 @@ impl<'mir, 'tcx, Prov: Provenance, Extra> Frame<'mir, 'tcx, Prov, Extra> {
     }
 }
 
+// FIXME: only used by miri, should be removed once translatable.
 impl<'tcx> fmt::Display for FrameInfo<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         ty::tls::with(|tcx| {
@@ -264,6 +266,21 @@ impl<'tcx> fmt::Display for FrameInfo<'tcx> {
     }
 }
 
+impl<'tcx> FrameInfo<'tcx> {
+    pub fn as_note(&self, tcx: TyCtxt<'tcx>) -> errors::FrameNote {
+        let span = self.span;
+        if tcx.def_key(self.instance.def_id()).disambiguated_data.data == DefPathData::ClosureExpr {
+            errors::FrameNote { where_: "closure", span, instance: String::new(), times: 0 }
+        } else {
+            let instance = format!("{}", self.instance);
+            // Note: this triggers a `good_path_bug` state, which means that if we ever get here
+            // we must emit a diagnostic. We should never display a `FrameInfo` unless we
+            // actually want to emit a warning or error to the user.
+            errors::FrameNote { where_: "instance", span, instance, times: 0 }
+        }
+    }
+}
+
 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> HasDataLayout for InterpCx<'mir, 'tcx, M> {
     #[inline]
     fn data_layout(&self) -> &TargetDataLayout {
@@ -620,7 +637,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
                 // Check if this brought us over the size limit.
                 if size > self.max_size_of_val() {
-                    throw_ub!(InvalidMeta("total size is bigger than largest supported object"));
+                    throw_ub!(InvalidMeta(InvalidMetaKind::TooBig));
                 }
                 Ok(Some((size, align)))
             }
@@ -638,7 +655,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let size = elem.size.bytes().saturating_mul(len); // we rely on `max_size_of_val` being smaller than `u64::MAX`.
                 let size = Size::from_bytes(size);
                 if size > self.max_size_of_val() {
-                    throw_ub!(InvalidMeta("slice is bigger than largest supported object"));
+                    throw_ub!(InvalidMeta(InvalidMetaKind::SliceTooBig));
                 }
                 Ok(Some((size, elem.align.abi)))
             }
@@ -746,7 +763,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             mir::UnwindAction::Cleanup(block) => Left(mir::Location { block, statement_index: 0 }),
             mir::UnwindAction::Continue => Right(self.frame_mut().body.span),
             mir::UnwindAction::Unreachable => {
-                throw_ub_format!("unwinding past a stack frame that does not allow unwinding")
+                throw_ub_custom!(fluent::const_eval_unreachable_unwind);
             }
             mir::UnwindAction::Terminate => {
                 self.frame_mut().loc = Right(self.frame_mut().body.span);
@@ -785,7 +802,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
         );
         if unwinding && self.frame_idx() == 0 {
-            throw_ub_format!("unwinding past the topmost frame of the stack");
+            throw_ub_custom!(fluent::const_eval_unwind_past_top);
         }
 
         // Copy return value. Must of course happen *before* we deallocate the locals.
@@ -873,7 +890,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // StorageLive expects the local to be dead, and marks it live.
         let old = mem::replace(&mut self.frame_mut().locals[local].value, local_val);
         if !matches!(old, LocalValue::Dead) {
-            throw_ub_format!("StorageLive on a local that was already live");
+            throw_ub_custom!(fluent::const_eval_double_storage_live);
         }
         Ok(())
     }
@@ -916,7 +933,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 ErrorHandled::Reported(err) => {
                     if !err.is_tainted_by_errors() && let Some(span) = span {
                         // To make it easier to figure out where this error comes from, also add a note at the current location.
-                        self.tcx.sess.span_note_without_error(span, "erroneous constant used");
+                        self.tcx.sess.emit_note(ErroneousConstUsed { span });
                     }
                     err_inval!(AlreadyReported(err))
                 }
diff --git a/compiler/rustc_const_eval/src/interpret/intern.rs b/compiler/rustc_const_eval/src/interpret/intern.rs
index c2b82ba9b07..7b11ad33091 100644
--- a/compiler/rustc_const_eval/src/interpret/intern.rs
+++ b/compiler/rustc_const_eval/src/interpret/intern.rs
@@ -28,6 +28,7 @@ use super::{
     ValueVisitor,
 };
 use crate::const_eval;
+use crate::errors::{DanglingPtrInFinal, UnsupportedUntypedPointer};
 
 pub trait CompileTimeMachine<'mir, 'tcx, T> = Machine<
         'mir,
@@ -320,10 +321,12 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
     }
 }
 
+/// How a constant value should be interned.
 #[derive(Copy, Clone, Debug, PartialEq, Hash, Eq)]
 pub enum InternKind {
     /// The `mutability` of the static, ignoring the type which may have interior mutability.
     Static(hir::Mutability),
+    /// A `const` item
     Constant,
     Promoted,
 }
@@ -388,8 +391,7 @@ pub fn intern_const_alloc_recursive<
                 ecx.tcx.sess.delay_span_bug(
                     ecx.tcx.span,
                     format!(
-                        "error during interning should later cause validation failure: {}",
-                        error
+                        "error during interning should later cause validation failure: {error:?}"
                     ),
                 );
             }
@@ -425,14 +427,16 @@ pub fn intern_const_alloc_recursive<
                     // immutability is so important.
                     alloc.mutability = Mutability::Not;
                 }
+                // If it's a constant, we should not have any "leftovers" as everything
+                // is tracked by const-checking.
+                // FIXME: downgrade this to a warning? It rejects some legitimate consts,
+                // such as `const CONST_RAW: *const Vec<i32> = &Vec::new() as *const _;`.
+                //
+                // NOTE: it looks likes this code path is only reachable when we try to intern
+                // something that cannot be promoted, which in constants means values that have
+                // drop glue, such as the example above.
                 InternKind::Constant => {
-                    // If it's a constant, we should not have any "leftovers" as everything
-                    // is tracked by const-checking.
-                    // FIXME: downgrade this to a warning? It rejects some legitimate consts,
-                    // such as `const CONST_RAW: *const Vec<i32> = &Vec::new() as *const _;`.
-                    ecx.tcx
-                        .sess
-                        .span_err(ecx.tcx.span, "untyped pointers are not allowed in constant");
+                    ecx.tcx.sess.emit_err(UnsupportedUntypedPointer { span: ecx.tcx.span });
                     // For better errors later, mark the allocation as immutable.
                     alloc.mutability = Mutability::Not;
                 }
@@ -447,10 +451,7 @@ pub fn intern_const_alloc_recursive<
         } else if ecx.memory.dead_alloc_map.contains_key(&alloc_id) {
             // Codegen does not like dangling pointers, and generally `tcx` assumes that
             // all allocations referenced anywhere actually exist. So, make sure we error here.
-            let reported = ecx
-                .tcx
-                .sess
-                .span_err(ecx.tcx.span, "encountered dangling pointer in final constant");
+            let reported = ecx.tcx.sess.emit_err(DanglingPtrInFinal { span: ecx.tcx.span });
             return Err(reported);
         } else if ecx.tcx.try_get_global_alloc(alloc_id).is_none() {
             // We have hit an `AllocId` that is neither in local or global memory and isn't
diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
index a77c699c22f..fb24cf48a9a 100644
--- a/compiler/rustc_const_eval/src/interpret/intrinsics.rs
+++ b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
@@ -22,6 +22,8 @@ use super::{
     Pointer,
 };
 
+use crate::fluent_generated as fluent;
+
 mod caller_location;
 
 fn numeric_intrinsic<Prov>(name: Symbol, bits: u128, kind: Primitive) -> Scalar<Prov> {
@@ -198,15 +200,18 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         ty
                     ),
                 };
-                let (nonzero, intrinsic_name) = match intrinsic_name {
+                let (nonzero, actual_intrinsic_name) = match intrinsic_name {
                     sym::cttz_nonzero => (true, sym::cttz),
                     sym::ctlz_nonzero => (true, sym::ctlz),
                     other => (false, other),
                 };
                 if nonzero && bits == 0 {
-                    throw_ub_format!("`{}_nonzero` called on 0", intrinsic_name);
+                    throw_ub_custom!(
+                        fluent::const_eval_call_nonzero_intrinsic,
+                        name = intrinsic_name,
+                    );
                 }
-                let out_val = numeric_intrinsic(intrinsic_name, bits, kind);
+                let out_val = numeric_intrinsic(actual_intrinsic_name, bits, kind);
                 self.write_scalar(out_val, dest)?;
             }
             sym::saturating_add | sym::saturating_sub => {
@@ -253,9 +258,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     let layout = self.layout_of(substs.type_at(0))?;
                     let r_val = r.to_scalar().to_bits(layout.size)?;
                     if let sym::unchecked_shl | sym::unchecked_shr = intrinsic_name {
-                        throw_ub_format!("overflowing shift by {} in `{}`", r_val, intrinsic_name);
+                        throw_ub_custom!(
+                            fluent::const_eval_overflow_shift,
+                            val = r_val,
+                            name = intrinsic_name
+                        );
                     } else {
-                        throw_ub_format!("overflow executing `{}`", intrinsic_name);
+                        throw_ub_custom!(fluent::const_eval_overflow, name = intrinsic_name);
                     }
                 }
                 self.write_scalar(val, dest)?;
@@ -314,17 +323,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         (Err(_), _) | (_, Err(_)) => {
                             // We managed to find a valid allocation for one pointer, but not the other.
                             // That means they are definitely not pointing to the same allocation.
-                            throw_ub_format!(
-                                "`{}` called on pointers into different allocations",
-                                intrinsic_name
+                            throw_ub_custom!(
+                                fluent::const_eval_different_allocations,
+                                name = intrinsic_name,
                             );
                         }
                         (Ok((a_alloc_id, a_offset, _)), Ok((b_alloc_id, b_offset, _))) => {
                             // Found allocation for both. They must be into the same allocation.
                             if a_alloc_id != b_alloc_id {
-                                throw_ub_format!(
-                                    "`{}` called on pointers into different allocations",
-                                    intrinsic_name
+                                throw_ub_custom!(
+                                    fluent::const_eval_different_allocations,
+                                    name = intrinsic_name,
                                 );
                             }
                             // Use these offsets for distance calculation.
@@ -344,11 +353,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     if overflowed {
                         // a < b
                         if intrinsic_name == sym::ptr_offset_from_unsigned {
-                            throw_ub_format!(
-                                "`{}` called when first pointer has smaller offset than second: {} < {}",
-                                intrinsic_name,
-                                a_offset,
-                                b_offset,
+                            throw_ub_custom!(
+                                fluent::const_eval_unsigned_offset_from_overflow,
+                                a_offset = a_offset,
+                                b_offset = b_offset,
                             );
                         }
                         // The signed form of the intrinsic allows this. If we interpret the
@@ -356,9 +364,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         // seems *positive*, they were more than isize::MAX apart.
                         let dist = val.to_target_isize(self)?;
                         if dist >= 0 {
-                            throw_ub_format!(
-                                "`{}` called when first pointer is too far before second",
-                                intrinsic_name
+                            throw_ub_custom!(
+                                fluent::const_eval_offset_from_underflow,
+                                name = intrinsic_name,
                             );
                         }
                         dist
@@ -368,9 +376,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         // If converting to isize produced a *negative* result, we had an overflow
                         // because they were more than isize::MAX apart.
                         if dist < 0 {
-                            throw_ub_format!(
-                                "`{}` called when first pointer is too far ahead of second",
-                                intrinsic_name
+                            throw_ub_custom!(
+                                fluent::const_eval_offset_from_overflow,
+                                name = intrinsic_name,
                             );
                         }
                         dist
@@ -513,7 +521,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let op = self.eval_operand(op, None)?;
                 let cond = self.read_scalar(&op)?.to_bool()?;
                 if !cond {
-                    throw_ub_format!("`assume` called with `false`");
+                    throw_ub_custom!(fluent::const_eval_assume_false);
                 }
                 Ok(())
             }
@@ -542,7 +550,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let (res, overflow, _ty) = self.overflowing_binary_op(BinOp::Rem, &a, &b)?;
         assert!(!overflow); // All overflow is UB, so this should never return on overflow.
         if res.assert_bits(a.layout.size) != 0 {
-            throw_ub_format!("exact_div: {} cannot be divided by {} without remainder", a, b)
+            throw_ub_custom!(
+                fluent::const_eval_exact_div_has_remainder,
+                a = format!("{a}"),
+                b = format!("{b}")
+            )
         }
         // `Rem` says this is all right, so we can let `Div` do its job.
         self.binop_ignore_overflow(BinOp::Div, &a, &b, dest)
@@ -638,9 +650,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // `checked_mul` enforces a too small bound (the correct one would probably be target_isize_max),
         // but no actual allocation can be big enough for the difference to be noticeable.
         let size = size.checked_mul(count, self).ok_or_else(|| {
-            err_ub_format!(
-                "overflow computing total size of `{}`",
-                if nonoverlapping { "copy_nonoverlapping" } else { "copy" }
+            err_ub_custom!(
+                fluent::const_eval_size_overflow,
+                name = if nonoverlapping { "copy_nonoverlapping" } else { "copy" }
             )
         })?;
 
@@ -664,10 +676,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
         // `checked_mul` enforces a too small bound (the correct one would probably be target_isize_max),
         // but no actual allocation can be big enough for the difference to be noticeable.
-        let len = layout
-            .size
-            .checked_mul(count, self)
-            .ok_or_else(|| err_ub_format!("overflow computing total size of `write_bytes`"))?;
+        let len = layout.size.checked_mul(count, self).ok_or_else(|| {
+            err_ub_custom!(fluent::const_eval_size_overflow, name = "write_bytes")
+        })?;
 
         let bytes = std::iter::repeat(byte).take(len.bytes_usize());
         self.write_bytes_ptr(dst, bytes)
@@ -691,7 +702,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 return Ok(&[]);
             };
             if alloc_ref.has_provenance() {
-                throw_ub_format!("`raw_eq` on bytes with provenance");
+                throw_ub_custom!(fluent::const_eval_raw_eq_with_provenance);
             }
             alloc_ref.get_bytes_strip_provenance()
         };
diff --git a/compiler/rustc_const_eval/src/interpret/memory.rs b/compiler/rustc_const_eval/src/interpret/memory.rs
index d5b6a581a79..1125d8d1f0e 100644
--- a/compiler/rustc_const_eval/src/interpret/memory.rs
+++ b/compiler/rustc_const_eval/src/interpret/memory.rs
@@ -19,6 +19,7 @@ use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TyCtxt};
 use rustc_target::abi::{Align, HasDataLayout, Size};
 
 use crate::const_eval::CheckAlignment;
+use crate::fluent_generated as fluent;
 
 use super::{
     alloc_range, AllocBytes, AllocId, AllocMap, AllocRange, Allocation, CheckInAllocMsg,
@@ -200,7 +201,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         align: Align,
         kind: MemoryKind<M::MemoryKind>,
     ) -> InterpResult<'tcx, Pointer<M::Provenance>> {
-        let alloc = Allocation::uninit(size, align, M::PANIC_ON_ALLOC_FAIL)?;
+        let alloc = if M::PANIC_ON_ALLOC_FAIL {
+            Allocation::uninit(size, align)
+        } else {
+            Allocation::try_uninit(size, align)?
+        };
         self.allocate_raw_ptr(alloc, kind)
     }
 
@@ -242,9 +247,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx, Pointer<M::Provenance>> {
         let (alloc_id, offset, _prov) = self.ptr_get_alloc_id(ptr)?;
         if offset.bytes() != 0 {
-            throw_ub_format!(
-                "reallocating {:?} which does not point to the beginning of an object",
-                ptr
+            throw_ub_custom!(
+                fluent::const_eval_realloc_or_alloc_with_offset,
+                ptr = format!("{ptr:?}"),
+                kind = "realloc"
             );
         }
 
@@ -280,9 +286,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         trace!("deallocating: {alloc_id:?}");
 
         if offset.bytes() != 0 {
-            throw_ub_format!(
-                "deallocating {:?} which does not point to the beginning of an object",
-                ptr
+            throw_ub_custom!(
+                fluent::const_eval_realloc_or_alloc_with_offset,
+                ptr = format!("{ptr:?}"),
+                kind = "dealloc",
             );
         }
 
@@ -290,13 +297,25 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             // Deallocating global memory -- always an error
             return Err(match self.tcx.try_get_global_alloc(alloc_id) {
                 Some(GlobalAlloc::Function(..)) => {
-                    err_ub_format!("deallocating {alloc_id:?}, which is a function")
+                    err_ub_custom!(
+                        fluent::const_eval_invalid_dealloc,
+                        alloc_id = alloc_id,
+                        kind = "fn",
+                    )
                 }
                 Some(GlobalAlloc::VTable(..)) => {
-                    err_ub_format!("deallocating {alloc_id:?}, which is a vtable")
+                    err_ub_custom!(
+                        fluent::const_eval_invalid_dealloc,
+                        alloc_id = alloc_id,
+                        kind = "vtable",
+                    )
                 }
                 Some(GlobalAlloc::Static(..) | GlobalAlloc::Memory(..)) => {
-                    err_ub_format!("deallocating {alloc_id:?}, which is static memory")
+                    err_ub_custom!(
+                        fluent::const_eval_invalid_dealloc,
+                        alloc_id = alloc_id,
+                        kind = "static_mem"
+                    )
                 }
                 None => err_ub!(PointerUseAfterFree(alloc_id)),
             }
@@ -304,21 +323,25 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         };
 
         if alloc.mutability.is_not() {
-            throw_ub_format!("deallocating immutable allocation {alloc_id:?}");
+            throw_ub_custom!(fluent::const_eval_dealloc_immutable, alloc = alloc_id,);
         }
         if alloc_kind != kind {
-            throw_ub_format!(
-                "deallocating {alloc_id:?}, which is {alloc_kind} memory, using {kind} deallocation operation"
+            throw_ub_custom!(
+                fluent::const_eval_dealloc_kind_mismatch,
+                alloc = alloc_id,
+                alloc_kind = format!("{alloc_kind}"),
+                kind = format!("{kind}"),
             );
         }
         if let Some((size, align)) = old_size_and_align {
             if size != alloc.size() || align != alloc.align {
-                throw_ub_format!(
-                    "incorrect layout on deallocation: {alloc_id:?} has size {} and alignment {}, but gave size {} and alignment {}",
-                    alloc.size().bytes(),
-                    alloc.align.bytes(),
-                    size.bytes(),
-                    align.bytes(),
+                throw_ub_custom!(
+                    fluent::const_eval_dealloc_incorrect_layout,
+                    alloc = alloc_id,
+                    size = alloc.size().bytes(),
+                    align = alloc.align.bytes(),
+                    size_found = size.bytes(),
+                    align_found = align.bytes(),
                 )
             }
         }
@@ -1166,7 +1189,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     if (src_offset <= dest_offset && src_offset + size > dest_offset)
                         || (dest_offset <= src_offset && dest_offset + size > src_offset)
                     {
-                        throw_ub_format!("copy_nonoverlapping called on overlapping ranges")
+                        throw_ub_custom!(fluent::const_eval_copy_nonoverlapping_overlapping);
                     }
                 }
 
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs
index 586e8f063ee..7269ff8d53c 100644
--- a/compiler/rustc_const_eval/src/interpret/terminator.rs
+++ b/compiler/rustc_const_eval/src/interpret/terminator.rs
@@ -15,6 +15,7 @@ use super::{
     FnVal, ImmTy, Immediate, InterpCx, InterpResult, MPlaceTy, Machine, MemoryKind, OpTy, Operand,
     PlaceTy, Scalar, StackPopCleanup,
 };
+use crate::fluent_generated as fluent;
 
 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     pub(super) fn eval_terminator(
@@ -172,7 +173,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             InlineAsm { template, ref operands, options, destination, .. } => {
                 M::eval_inline_asm(self, template, operands, options)?;
                 if options.contains(InlineAsmOptions::NORETURN) {
-                    throw_ub_format!("returned from noreturn inline assembly");
+                    throw_ub_custom!(fluent::const_eval_noreturn_asm_returned);
                 }
                 self.go_to_block(
                     destination
@@ -288,15 +289,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             return Ok(());
         }
         // Find next caller arg.
-        let (caller_arg, caller_abi) = caller_args.next().ok_or_else(|| {
-            err_ub_format!("calling a function with fewer arguments than it requires")
-        })?;
+        let Some((caller_arg, caller_abi)) = caller_args.next() else {
+            throw_ub_custom!(fluent::const_eval_not_enough_caller_args);
+        };
         // Now, check
         if !Self::check_argument_compat(caller_abi, callee_abi) {
-            throw_ub_format!(
-                "calling a function with argument of type {:?} passing data of type {:?}",
-                callee_arg.layout.ty,
-                caller_arg.layout.ty
+            let callee_ty = format!("{}", callee_arg.layout.ty);
+            let caller_ty = format!("{}", caller_arg.layout.ty);
+            throw_ub_custom!(
+                fluent::const_eval_incompatible_types,
+                callee_ty = callee_ty,
+                caller_ty = caller_ty,
             )
         }
         // Special handling for unsized parameters.
@@ -398,10 +401,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
                 if M::enforce_abi(self) {
                     if caller_fn_abi.conv != callee_fn_abi.conv {
-                        throw_ub_format!(
-                            "calling a function with calling convention {:?} using calling convention {:?}",
-                            callee_fn_abi.conv,
-                            caller_fn_abi.conv
+                        throw_ub_custom!(
+                            fluent::const_eval_incompatible_calling_conventions,
+                            callee_conv = format!("{:?}", callee_fn_abi.conv),
+                            caller_conv = format!("{:?}", caller_fn_abi.conv),
                         )
                     }
                 }
@@ -508,15 +511,16 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         "mismatch between callee ABI and callee body arguments"
                     );
                     if caller_args.next().is_some() {
-                        throw_ub_format!("calling a function with more arguments than it expected")
+                        throw_ub_custom!(fluent::const_eval_too_many_caller_args);
                     }
                     // Don't forget to check the return type!
                     if !Self::check_argument_compat(&caller_fn_abi.ret, &callee_fn_abi.ret) {
-                        throw_ub_format!(
-                            "calling a function with return type {:?} passing \
-                                    return place of type {:?}",
-                            callee_fn_abi.ret.layout.ty,
-                            caller_fn_abi.ret.layout.ty,
+                        let callee_ty = format!("{}", callee_fn_abi.ret.layout.ty);
+                        let caller_ty = format!("{}", caller_fn_abi.ret.layout.ty);
+                        throw_ub_custom!(
+                            fluent::const_eval_incompatible_return_types,
+                            callee_ty = callee_ty,
+                            caller_ty = caller_ty,
                         )
                     }
                 };
@@ -587,9 +591,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     let (recv, vptr) = self.unpack_dyn_star(&receiver_place.into())?;
                     let (dyn_ty, dyn_trait) = self.get_ptr_vtable(vptr)?;
                     if dyn_trait != data.principal() {
-                        throw_ub_format!(
-                            "`dyn*` call on a pointer whose vtable does not match its type"
-                        );
+                        throw_ub_custom!(fluent::const_eval_dyn_star_call_vtable_mismatch);
                     }
                     let recv = recv.assert_mem_place(); // we passed an MPlaceTy to `unpack_dyn_star` so we definitely still have one
 
@@ -609,9 +611,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     let vptr = receiver_place.meta.unwrap_meta().to_pointer(self)?;
                     let (dyn_ty, dyn_trait) = self.get_ptr_vtable(vptr)?;
                     if dyn_trait != data.principal() {
-                        throw_ub_format!(
-                            "`dyn` call on a pointer whose vtable does not match its type"
-                        );
+                        throw_ub_custom!(fluent::const_eval_dyn_call_vtable_mismatch);
                     }
 
                     // It might be surprising that we use a pointer as the receiver even if this
@@ -623,7 +623,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 // Now determine the actual method to call. We can do that in two different ways and
                 // compare them to ensure everything fits.
                 let Some(ty::VtblEntry::Method(fn_inst)) = self.get_vtable_entries(vptr)?.get(idx).copied() else {
-                    throw_ub_format!("`dyn` call trying to call something that is not a method")
+                    // 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:#?}");
                 if cfg!(debug_assertions) {
diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs
index 01b77289937..21c655988a0 100644
--- a/compiler/rustc_const_eval/src/interpret/validity.rs
+++ b/compiler/rustc_const_eval/src/interpret/validity.rs
@@ -4,7 +4,7 @@
 //! That's useful because it means other passes (e.g. promotion) can rely on `const`s
 //! to be const-safe.
 
-use std::fmt::{Display, Write};
+use std::fmt::Write;
 use std::num::NonZeroUsize;
 
 use either::{Left, Right};
@@ -12,7 +12,10 @@ use either::{Left, Right};
 use rustc_ast::Mutability;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
-use rustc_middle::mir::interpret::InterpError;
+use rustc_middle::mir::interpret::{
+    ExpectedKind, InterpError, InvalidMetaKind, PointerKind, ValidationErrorInfo,
+    ValidationErrorKind, ValidationErrorKind::*,
+};
 use rustc_middle::ty;
 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
 use rustc_span::symbol::{sym, Symbol};
@@ -30,14 +33,7 @@ use super::{
 };
 
 macro_rules! throw_validation_failure {
-    ($where:expr, { $( $what_fmt:tt )* } $( expected { $( $expected_fmt:tt )* } )?) => {{
-        let mut msg = String::new();
-        msg.push_str("encountered ");
-        write!(&mut msg, $($what_fmt)*).unwrap();
-        $(
-            msg.push_str(", but expected ");
-            write!(&mut msg, $($expected_fmt)*).unwrap();
-        )?
+    ($where:expr, $kind: expr) => {{
         let where_ = &$where;
         let path = if !where_.is_empty() {
             let mut path = String::new();
@@ -46,7 +42,8 @@ macro_rules! throw_validation_failure {
         } else {
             None
         };
-        throw_ub!(ValidationFailure { path, msg })
+
+        throw_ub!(Validation(ValidationErrorInfo { path, kind: $kind }))
     }};
 }
 
@@ -82,22 +79,22 @@ macro_rules! throw_validation_failure {
 ///
 macro_rules! try_validation {
     ($e:expr, $where:expr,
-    $( $( $p:pat_param )|+ => { $( $what_fmt:tt )* } $( expected { $( $expected_fmt:tt )* } )? ),+ $(,)?
+    $( $( $p:pat_param )|+ => $kind: expr ),+ $(,)?
     ) => {{
         match $e {
             Ok(x) => x,
             // We catch the error and turn it into a validation failure. We are okay with
             // allocation here as this can only slow down builds that fail anyway.
-            Err(e) => match e.kind() {
+            Err(e) => match e.into_parts() {
                 $(
-                    InterpError::UndefinedBehavior($($p)|+) =>
+                    (InterpError::UndefinedBehavior($($p)|+), _) =>
                        throw_validation_failure!(
                             $where,
-                            { $( $what_fmt )* } $( expected { $( $expected_fmt )* } )?
+                            $kind
                         )
                 ),+,
                 #[allow(unreachable_patterns)]
-                _ => Err::<!, _>(e)?,
+                (e, rest) => Err::<!, _>($crate::interpret::InterpErrorInfo::from_parts(e, rest))?,
             }
         }
     }};
@@ -160,6 +157,7 @@ impl<T: Copy + Eq + Hash + std::fmt::Debug, PATH: Default> RefTracking<T, PATH>
     }
 }
 
+// FIXME make this translatable as well?
 /// Format a path
 fn write_path(out: &mut String, path: &[PathElem]) {
     use self::PathElem::*;
@@ -185,26 +183,6 @@ fn write_path(out: &mut String, path: &[PathElem]) {
     }
 }
 
-// Formats such that a sentence like "expected something {}" to mean
-// "expected something <in the given range>" makes sense.
-fn wrapping_range_format(r: WrappingRange, max_hi: u128) -> String {
-    let WrappingRange { start: lo, end: hi } = r;
-    assert!(hi <= max_hi);
-    if lo > hi {
-        format!("less or equal to {}, or greater or equal to {}", hi, lo)
-    } else if lo == hi {
-        format!("equal to {}", lo)
-    } else if lo == 0 {
-        assert!(hi < max_hi, "should not be printing if the range covers everything");
-        format!("less or equal to {}", hi)
-    } else if hi == max_hi {
-        assert!(lo > 0, "should not be printing if the range covers everything");
-        format!("greater or equal to {}", lo)
-    } else {
-        format!("in the range {:?}", r)
-    }
-}
-
 struct ValidityVisitor<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
     /// The `path` may be pushed to, but the part that is present when a function
     /// starts must not be changed!  `visit_fields` and `visit_array` rely on
@@ -311,19 +289,19 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
     fn read_immediate(
         &self,
         op: &OpTy<'tcx, M::Provenance>,
-        expected: impl Display,
+        expected: ExpectedKind,
     ) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
         Ok(try_validation!(
             self.ecx.read_immediate(op),
             self.path,
-            InvalidUninitBytes(None) => { "uninitialized memory" } expected { "{expected}" }
+            InvalidUninitBytes(None) => Uninit { expected }
         ))
     }
 
     fn read_scalar(
         &self,
         op: &OpTy<'tcx, M::Provenance>,
-        expected: impl Display,
+        expected: ExpectedKind,
     ) -> InterpResult<'tcx, Scalar<M::Provenance>> {
         Ok(self.read_immediate(op, expected)?.to_scalar())
     }
@@ -342,8 +320,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                     self.ecx.get_ptr_vtable(vtable),
                     self.path,
                     DanglingIntPointer(..) |
-                    InvalidVTablePointer(..) =>
-                        { "{vtable}" } expected { "a vtable pointer" },
+                    InvalidVTablePointer(..) => InvalidVTablePtr { value: format!("{vtable}") }
                 );
                 // FIXME: check if the type/trait match what ty::Dynamic says?
             }
@@ -366,10 +343,9 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
     fn check_safe_pointer(
         &mut self,
         value: &OpTy<'tcx, M::Provenance>,
-        kind: &str,
+        ptr_kind: PointerKind,
     ) -> InterpResult<'tcx> {
-        let place =
-            self.ecx.ref_to_mplace(&self.read_immediate(value, format_args!("a {kind}"))?)?;
+        let place = self.ecx.ref_to_mplace(&self.read_immediate(value, ptr_kind.into())?)?;
         // Handle wide pointers.
         // Check metadata early, for better diagnostics
         if place.layout.is_unsized() {
@@ -379,7 +355,10 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
         let size_and_align = try_validation!(
             self.ecx.size_and_align_of_mplace(&place),
             self.path,
-            InvalidMeta(msg) => { "invalid {} metadata: {}", kind, msg },
+            InvalidMeta(msg) => match msg {
+                InvalidMetaKind::SliceTooBig => InvalidMetaSliceTooLarge { ptr_kind },
+                InvalidMetaKind::TooBig => InvalidMetaTooLarge { ptr_kind },
+            }
         );
         let (size, align) = size_and_align
             // for the purpose of validity, consider foreign types to have
@@ -395,31 +374,30 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                 CheckInAllocMsg::InboundsTest, // will anyway be replaced by validity message
             ),
             self.path,
-            AlignmentCheckFailed { required, has } =>
-                {
-                    "an unaligned {kind} (required {} byte alignment but found {})",
-                    required.bytes(),
-                    has.bytes(),
-                },
-            DanglingIntPointer(0, _) =>
-                { "a null {kind}" },
-            DanglingIntPointer(i, _) =>
-                {
-                    "a dangling {kind} ({pointer} has no provenance)",
-                    pointer = Pointer::<Option<AllocId>>::from_addr_invalid(*i),
-                },
-            PointerOutOfBounds { .. } =>
-                { "a dangling {kind} (going beyond the bounds of its allocation)" },
+            AlignmentCheckFailed { required, has } => UnalignedPtr {
+                ptr_kind,
+                required_bytes: required.bytes(),
+                found_bytes: has.bytes()
+            },
+            DanglingIntPointer(0, _) => NullPtr { ptr_kind },
+            DanglingIntPointer(i, _) => DanglingPtrNoProvenance {
+                ptr_kind,
+                // FIXME this says "null pointer" when null but we need translate
+                pointer: format!("{}", Pointer::<Option<AllocId>>::from_addr_invalid(i))
+            },
+            PointerOutOfBounds { .. } => DanglingPtrOutOfBounds {
+                ptr_kind
+            },
             // This cannot happen during const-eval (because interning already detects
             // dangling pointers), but it can happen in Miri.
-            PointerUseAfterFree(..) =>
-                { "a dangling {kind} (use-after-free)" },
+            PointerUseAfterFree(..) => DanglingPtrUseAfterFree {
+                ptr_kind,
+            },
         );
         // Do not allow pointers to uninhabited types.
         if place.layout.abi.is_uninhabited() {
-            throw_validation_failure!(self.path,
-                { "a {kind} pointing to uninhabited type {}", place.layout.ty }
-            )
+            let ty = place.layout.ty;
+            throw_validation_failure!(self.path, PtrToUninhabited { ptr_kind, ty })
         }
         // Recursive checking
         if let Some(ref_tracking) = self.ref_tracking.as_deref_mut() {
@@ -441,9 +419,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                             // this check is so important.
                             // This check is reachable when the const just referenced the static,
                             // but never read it (so we never entered `before_access_global`).
-                            throw_validation_failure!(self.path,
-                                { "a {} pointing to a static variable in a constant", kind }
-                            );
+                            throw_validation_failure!(self.path, PtrToStatic { ptr_kind });
                         }
                         // We skip recursively checking other statics. These statics must be sound by
                         // themselves, and the only way to get broken statics here is by using
@@ -464,9 +440,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                             // This should be unreachable, but if someone manages to copy a pointer
                             // out of a `static`, then that pointer might point to mutable memory,
                             // and we would catch that here.
-                            throw_validation_failure!(self.path,
-                                { "a {} pointing to mutable memory in a constant", kind }
-                            );
+                            throw_validation_failure!(self.path, PtrToMut { ptr_kind });
                         }
                     }
                     // Nothing to check for these.
@@ -496,22 +470,24 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
         let ty = value.layout.ty;
         match ty.kind() {
             ty::Bool => {
-                let value = self.read_scalar(value, "a boolean")?;
+                let value = self.read_scalar(value, ExpectedKind::Bool)?;
                 try_validation!(
                     value.to_bool(),
                     self.path,
-                    InvalidBool(..) =>
-                        { "{:x}", value } expected { "a boolean" },
+                    InvalidBool(..) => ValidationErrorKind::InvalidBool {
+                        value: format!("{value:x}"),
+                    }
                 );
                 Ok(true)
             }
             ty::Char => {
-                let value = self.read_scalar(value, "a unicode scalar value")?;
+                let value = self.read_scalar(value, ExpectedKind::Char)?;
                 try_validation!(
                     value.to_char(),
                     self.path,
-                    InvalidChar(..) =>
-                        { "{:x}", value } expected { "a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)" },
+                    InvalidChar(..) => ValidationErrorKind::InvalidChar {
+                        value: format!("{value:x}"),
+                    }
                 );
                 Ok(true)
             }
@@ -521,16 +497,17 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                 let value = self.read_scalar(
                     value,
                     if matches!(ty.kind(), ty::Float(..)) {
-                        "a floating point number"
+                        ExpectedKind::Float
                     } else {
-                        "an integer"
+                        ExpectedKind::Int
                     },
                 )?;
                 // As a special exception we *do* match on a `Scalar` here, since we truly want
                 // to know its underlying representation (and *not* cast it to an integer).
                 if matches!(value, Scalar::Ptr(..)) {
-                    throw_validation_failure!(self.path,
-                        { "{:x}", value } expected { "plain (non-pointer) bytes" }
+                    throw_validation_failure!(
+                        self.path,
+                        ExpectedNonPtr { value: format!("{value:x}") }
                     )
                 }
                 Ok(true)
@@ -540,7 +517,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                 // actually enforce the strict rules for raw pointers (mostly because
                 // that lets us re-use `ref_to_mplace`).
                 let place =
-                    self.ecx.ref_to_mplace(&self.read_immediate(value, "a raw pointer")?)?;
+                    self.ecx.ref_to_mplace(&self.read_immediate(value, ExpectedKind::RawPtr)?)?;
                 if place.layout.is_unsized() {
                     self.check_wide_ptr_meta(place.meta, place.layout)?;
                 }
@@ -554,14 +531,14 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                     // a ZST).
                     let layout = self.ecx.layout_of(*ty)?;
                     if !layout.is_zst() {
-                        throw_validation_failure!(self.path, { "mutable reference in a `const`" });
+                        throw_validation_failure!(self.path, MutableRefInConst);
                     }
                 }
-                self.check_safe_pointer(value, "reference")?;
+                self.check_safe_pointer(value, PointerKind::Ref)?;
                 Ok(true)
             }
             ty::FnPtr(_sig) => {
-                let value = self.read_scalar(value, "a function pointer")?;
+                let value = self.read_scalar(value, ExpectedKind::FnPtr)?;
 
                 // If we check references recursively, also check that this points to a function.
                 if let Some(_) = self.ref_tracking {
@@ -570,19 +547,20 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                         self.ecx.get_ptr_fn(ptr),
                         self.path,
                         DanglingIntPointer(..) |
-                        InvalidFunctionPointer(..) =>
-                            { "{ptr}" } expected { "a function pointer" },
+                        InvalidFunctionPointer(..) => InvalidFnPtr {
+                            value: format!("{ptr}"),
+                        },
                     );
                     // FIXME: Check if the signature matches
                 } else {
                     // Otherwise (for standalone Miri), we have to still check it to be non-null.
                     if self.ecx.scalar_may_be_null(value)? {
-                        throw_validation_failure!(self.path, { "a null function pointer" });
+                        throw_validation_failure!(self.path, NullFnPtr);
                     }
                 }
                 Ok(true)
             }
-            ty::Never => throw_validation_failure!(self.path, { "a value of the never type `!`" }),
+            ty::Never => throw_validation_failure!(self.path, NeverVal),
             ty::Foreign(..) | ty::FnDef(..) => {
                 // Nothing to check.
                 Ok(true)
@@ -629,12 +607,9 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                 if start == 1 && end == max_value {
                     // Only null is the niche. So make sure the ptr is NOT null.
                     if self.ecx.scalar_may_be_null(scalar)? {
-                        throw_validation_failure!(self.path,
-                            { "a potentially null pointer" }
-                            expected {
-                                "something that cannot possibly fail to be {}",
-                                wrapping_range_format(valid_range, max_value)
-                            }
+                        throw_validation_failure!(
+                            self.path,
+                            NullablePtrOutOfRange { range: valid_range, max_value }
                         )
                     } else {
                         return Ok(());
@@ -645,12 +620,9 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                 } else {
                     // Conservatively, we reject, because the pointer *could* have a bad
                     // value.
-                    throw_validation_failure!(self.path,
-                        { "a pointer" }
-                        expected {
-                            "something that cannot possibly fail to be {}",
-                            wrapping_range_format(valid_range, max_value)
-                        }
+                    throw_validation_failure!(
+                        self.path,
+                        PtrOutOfRange { range: valid_range, max_value }
                     )
                 }
             }
@@ -659,9 +631,9 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
         if valid_range.contains(bits) {
             Ok(())
         } else {
-            throw_validation_failure!(self.path,
-                { "{}", bits }
-                expected { "something {}", wrapping_range_format(valid_range, max_value) }
+            throw_validation_failure!(
+                self.path,
+                OutOfRange { value: format!("{bits}"), range: valid_range, max_value }
             )
         }
     }
@@ -685,10 +657,11 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
             Ok(try_validation!(
                 this.ecx.read_discriminant(op),
                 this.path,
-                InvalidTag(val) =>
-                    { "{:x}", val } expected { "a valid enum tag" },
-                InvalidUninitBytes(None) =>
-                    { "uninitialized bytes" } expected { "a valid enum tag" },
+                InvalidTag(val) => InvalidEnumTag {
+                    value: format!("{val:x}"),
+                },
+
+                InvalidUninitBytes(None) => UninitEnumTag,
             )
             .1)
         })
@@ -730,7 +703,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
         // Special check preventing `UnsafeCell` inside unions in the inner part of constants.
         if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. })) {
             if !op.layout.ty.is_freeze(*self.ecx.tcx, self.ecx.param_env) {
-                throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
+                throw_validation_failure!(self.path, UnsafeCell);
             }
         }
         Ok(())
@@ -738,7 +711,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
 
     #[inline]
     fn visit_box(&mut self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx> {
-        self.check_safe_pointer(op, "box")?;
+        self.check_safe_pointer(op, PointerKind::Box)?;
         Ok(())
     }
 
@@ -756,7 +729,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
             if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. }))
                 && def.is_unsafe_cell()
             {
-                throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
+                throw_validation_failure!(self.path, UnsafeCell);
             }
         }
 
@@ -775,14 +748,13 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
         // MyNewtype and then the scalar in there).
         match op.layout.abi {
             Abi::Uninhabited => {
-                throw_validation_failure!(self.path,
-                    { "a value of uninhabited type {:?}", op.layout.ty }
-                );
+                let ty = op.layout.ty;
+                throw_validation_failure!(self.path, UninhabitedVal { ty });
             }
             Abi::Scalar(scalar_layout) => {
                 if !scalar_layout.is_uninit_valid() {
                     // There is something to check here.
-                    let scalar = self.read_scalar(op, "initialized scalar value")?;
+                    let scalar = self.read_scalar(op, ExpectedKind::InitScalar)?;
                     self.visit_scalar(scalar, scalar_layout)?;
                 }
             }
@@ -792,7 +764,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                 // the other must be init.
                 if !a_layout.is_uninit_valid() && !b_layout.is_uninit_valid() {
                     let (a, b) =
-                        self.read_immediate(op, "initialized scalar value")?.to_scalar_pair();
+                        self.read_immediate(op, ExpectedKind::InitScalar)?.to_scalar_pair();
                     self.visit_scalar(a, a_layout)?;
                     self.visit_scalar(b, b_layout)?;
                 }
@@ -822,7 +794,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                 try_validation!(
                     self.ecx.read_bytes_ptr_strip_provenance(mplace.ptr, Size::from_bytes(len)),
                     self.path,
-                    InvalidUninitBytes(..) => { "uninitialized data in `str`" },
+                    InvalidUninitBytes(..) => { UninitStr },
                 );
             }
             ty::Array(tys, ..) | ty::Slice(tys)
@@ -852,7 +824,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                     Left(mplace) => mplace,
                     Right(imm) => match *imm {
                         Immediate::Uninit =>
-                            throw_validation_failure!(self.path, { "uninitialized bytes" }),
+                            throw_validation_failure!(self.path, UninitVal),
                         Immediate::Scalar(..) | Immediate::ScalarPair(..) =>
                             bug!("arrays/slices can never have Scalar/ScalarPair layout"),
                     }
@@ -888,7 +860,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                                 .unwrap();
                                 self.path.push(PathElem::ArrayElem(i));
 
-                                throw_validation_failure!(self.path, { "uninitialized bytes" })
+                                throw_validation_failure!(self.path, UninitVal)
                             }
 
                             // Propagate upwards (that will also check for unexpected errors).
@@ -929,12 +901,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         match visitor.visit_value(&op) {
             Ok(()) => Ok(()),
             // Pass through validation failures.
-            Err(err) if matches!(err.kind(), err_ub!(ValidationFailure { .. })) => Err(err),
+            Err(err) if matches!(err.kind(), err_ub!(Validation { .. })) => Err(err),
             // Complain about any other kind of UB error -- those are bad because we'd like to
             // report them in a way that shows *where* in the value the issue lies.
             Err(err) if matches!(err.kind(), InterpError::UndefinedBehavior(_)) => {
-                err.print_backtrace();
-                bug!("Unexpected Undefined Behavior error during validation: {}", err);
+                let (err, backtrace) = err.into_parts();
+                backtrace.print_backtrace();
+                bug!("Unexpected Undefined Behavior error during validation: {err:?}");
             }
             // Pass through everything else.
             Err(err) => Err(err),