Update compiler/rustc_const_eval/src/interpret/validity.rs

Co-authored-by: Ralf Jung <[email protected]>

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -722,6 +722,10 @@ fn mutability<'mir, 'tcx: 'mir>(
                     }
                     _ => mutability,
                 };
+                // In case this allocation exists in our alloc_map (which means it is
+                // the static we are evaluating), sanity-check the mutability.
+                // We can't do this for other statics as their allocations are only
+                // available via the query.
                 if let Some((_, alloc)) = ecx.memory.alloc_map.get(alloc_id) {
                     assert_eq!(alloc.mutability, mutability);
                 }