1 files changed, 5 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index b7b36c49459..c77047f8a2e 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -3053,6 +3053,11 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                 return;
             }
 
+            // Scalars which have invalid values cannot be undef.
+            if !scalar.is_always_valid(self) {
+                attrs.set(ArgAttribute::NoUndef);
+            }
+
             // Only pointer types handled below.
             if scalar.value != Pointer {
                 return;