bugfix: Decide the number of snapshots by the last member of the deref chain. (#8971)

Author: orizi

crates/cairo-lang-semantic/src/expr/compute.rs

@@ -3818,19 +3818,15 @@ fn member_access_expr<'db>(
                 derefed_expr =
                     ExprAndId { expr: cur_expr.clone(), id: ctx.arenas.exprs.alloc(cur_expr) };
             }
-            let (_, long_ty) =
+            let (n_snapshots, long_ty) =
                 finalized_snapshot_peeled_ty(ctx, derefed_expr.ty(), rhs_syntax.stable_ptr(db))?;
             let derefed_expr_concrete_struct_id = match long_ty {
                 TypeLongId::Concrete(ConcreteTypeId::Struct(concrete_struct_id)) => {
                     concrete_struct_id
                 }
                 _ => unreachable!(),
             };
-            let ty = if !deref_functions.is_empty() {
-                member.ty
-            } else {
-                wrap_in_snapshots(ctx.db, member.ty, n_snapshots)
-            };
+            let ty = wrap_in_snapshots(ctx.db, member.ty, n_snapshots);
             let mut final_expr = Expr::MemberAccess(ExprMemberAccess {
                 expr: derefed_expr.id,
                 concrete_struct_id: derefed_expr_concrete_struct_id,

crates/cairo-lang-semantic/src/expr/test_data/deref

@@ -202,3 +202,49 @@ error: Type `test::S1` cannot be dereferenced
  --> lib.cairo:13:14
     let _ = (*a);
              ^
+
+//! > ==========================================================================
+
+//! > Final deref return values should decide the number of snapshots - single snapshot.
+
+//! > test_runner_name
+test_function_diagnostics(expect_diagnostics: false)
+
+//! > function_code
+fn foo(a: Box<@A>) -> @usize {
+    a.b
+}
+
+//! > function_name
+foo
+
+//! > module_code
+struct A {
+    a: usize,
+    b: usize,
+}
+
+//! > expected_diagnostics
+
+//! > ==========================================================================
+
+//! > Final deref return values should decide the number of snapshots - multiple snapshots.
+
+//! > test_runner_name
+test_function_diagnostics(expect_diagnostics: false)
+
+//! > function_code
+fn foo(a: Box<@@@A>) -> @@@usize {
+    a.b
+}
+
+//! > function_name
+foo
+
+//! > module_code
+struct A {
+    a: usize,
+    b: usize,
+}
+
+//! > expected_diagnostics