1 files changed, 10 insertions, 2 deletions
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index f188923f876..0ab797134c0 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -1366,8 +1366,16 @@ pub enum NullOp<'tcx> {
     AlignOf,
     /// Returns the offset of a field
     OffsetOf(&'tcx List<(VariantIdx, FieldIdx)>),
-    /// cfg!(debug_assertions), but expanded in codegen
-    DebugAssertions,
+    /// Returns whether we want to check for library UB or language UB at monomorphization time.
+    /// Both kinds of UB evaluate to `true` in codegen, and only library UB evalutes to `true` in
+    /// const-eval/Miri, because the interpreter has its own better checks for language UB.
+    UbCheck(UbKind),
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
+pub enum UbKind {
+    LanguageUb,
+    LibraryUb,
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]