3 files changed, 13 insertions, 7 deletions
diff --git a/compiler/rustc_transmute/src/layout/tree.rs b/compiler/rustc_transmute/src/layout/tree.rs
index e8ddb0a43..49f24f66b 100644
--- a/compiler/rustc_transmute/src/layout/tree.rs
+++ b/compiler/rustc_transmute/src/layout/tree.rs
@@ -189,6 +189,8 @@ pub(crate) mod rustc {
         Unspecified,
         /// This error will be surfaced elsewhere by rustc, so don't surface it.
         UnknownLayout,
+        /// Overflow size
+        SizeOverflow,
         TypeError(ErrorGuaranteed),
     }
 
@@ -196,6 +198,7 @@ pub(crate) mod rustc {
         fn from(err: &LayoutError<'tcx>) -> Self {
             match err {
                 LayoutError::Unknown(..) | LayoutError::ReferencesError(..) => Self::UnknownLayout,
+                LayoutError::SizeOverflow(..) => Self::SizeOverflow,
                 err => unimplemented!("{:?}", err),
             }
         }
diff --git a/compiler/rustc_transmute/src/lib.rs b/compiler/rustc_transmute/src/lib.rs
index 05ad4a4a1..6c49e94dc 100644
--- a/compiler/rustc_transmute/src/lib.rs
+++ b/compiler/rustc_transmute/src/lib.rs
@@ -64,6 +64,10 @@ pub enum Reason {
     SrcLayoutUnknown,
     /// The layout of dst is unknown
     DstLayoutUnknown,
+    /// The size of src is overflow
+    SrcSizeOverflow,
+    /// The size of dst is overflow
+    DstSizeOverflow,
 }
 
 #[cfg(feature = "rustc")]
@@ -125,19 +129,16 @@ mod rustc {
             c: Const<'tcx>,
         ) -> Option<Self> {
             use rustc_middle::ty::ScalarInt;
-            use rustc_middle::ty::TypeVisitableExt;
             use rustc_span::symbol::sym;
 
-            let c = c.eval(tcx, param_env);
-
-            if let Err(err) = c.error_reported() {
+            let Ok(cv) = c.eval(tcx, param_env, None) else {
                 return Some(Self {
                     alignment: true,
                     lifetimes: true,
                     safety: true,
                     validity: true,
                 });
-            }
+            };
 
             let adt_def = c.ty().ty_adt_def()?;
 
@@ -149,8 +150,8 @@ mod rustc {
             );
 
             let variant = adt_def.non_enum_variant();
-            let fields = match c.try_to_valtree() {
-                Some(ValTree::Branch(branch)) => branch,
+            let fields = match cv {
+                ValTree::Branch(branch) => branch,
                 _ => {
                     return Some(Self {
                         alignment: true,
diff --git a/compiler/rustc_transmute/src/maybe_transmutable/mod.rs b/compiler/rustc_transmute/src/maybe_transmutable/mod.rs
index b223a90f7..c0141f1f8 100644
--- a/compiler/rustc_transmute/src/maybe_transmutable/mod.rs
+++ b/compiler/rustc_transmute/src/maybe_transmutable/mod.rs
@@ -85,6 +85,8 @@ mod rustc {
                 (_, Err(Err::UnknownLayout)) => Answer::No(Reason::DstLayoutUnknown),
                 (Err(Err::Unspecified), _) => Answer::No(Reason::SrcIsUnspecified),
                 (_, Err(Err::Unspecified)) => Answer::No(Reason::DstIsUnspecified),
+                (Err(Err::SizeOverflow), _) => Answer::No(Reason::SrcSizeOverflow),
+                (_, Err(Err::SizeOverflow)) => Answer::No(Reason::DstSizeOverflow),
                 (Ok(src), Ok(dst)) => {
                     MaybeTransmutableQuery { src, dst, scope, assume, context }.answer()
                 }