feat: add expression statements and assign expressions

src/middle/fold.rs

@@ -29,6 +29,9 @@ fn optimize_function(func: &mut MirFunction) {
                 // Replace the complex instruction with a simple constant use
                 *rvalue = Rvalue::Use(Operand::Constant(constant.clone()));
                 known_constants.insert(*local, constant);
+            } else {
+                // Reassigned to a non-computable value; remove older cached inferences
+                known_constants.remove(local);
             }
         }