Preventing box values from being const-folded.

commit-id:96c96792

crates/cairo-lang-lowering/src/optimizations/const_folding.rs

@@ -116,7 +116,8 @@ pub fn const_folding(db: &dyn LoweringGroup, lowered: &mut FlatLowered) {
                                     lowered.variables[inputs[0].var_id].ty,
                                     val.clone().into(),
                                 );
-                                var_info.insert(outputs[0], VarInfo::Const(value.clone()));
+                                // Not inserting the value into the `var_info` map because the
+                                // resulting box isn't an actual const at the Sierra level.
                                 *stmt =
                                     Statement::Const(StatementConst { value, output: outputs[0] });
                             }

tests/bug_samples/issue5411.cairo

@@ -0,0 +1,6 @@
+use core::nullable::NullableTrait;
+
+#[test]
+fn box_of_box() -> Nullable<Box<u32>> {
+    NullableTrait::<Box<u32>>::new(BoxTrait::new(16))
+}

tests/bug_samples/lib.cairo

@@ -40,6 +40,7 @@ mod issue4318;
 mod issue4380;
 mod issue4897;
 mod issue4937;
+mod issue5411;
 mod loop_break_in_match;
 mod loop_only_change;
 mod partial_param_local;