TEST: Add test for pass struct by ref

Author: ubaidsk

integration_tests/CMakeLists.txt

@@ -591,6 +591,7 @@ RUN(NAME structs_27          LABELS cpython llvm c)
 RUN(NAME structs_28          LABELS cpython llvm c)
 RUN(NAME structs_29          LABELS cpython llvm)
 RUN(NAME structs_30          LABELS cpython llvm c)
+RUN(NAME structs_31          LABELS cpython llvm c)
 
 RUN(NAME symbolics_01        LABELS cpython_sym c_sym)
 RUN(NAME symbolics_02        LABELS cpython_sym c_sym)

integration_tests/structs_31.py

@@ -0,0 +1,22 @@
+from lpython import packed, dataclass, i32, InOut
+
+@packed
+@dataclass
+class inner_struct:
+    a: i32
+
+@packed
+@dataclass
+class outer_struct:
+    b: inner_struct = inner_struct(0)
+
+def update_my_inner_struct(my_inner_struct: InOut[inner_struct]) -> None:
+    my_inner_struct.a = 99999
+
+def main() -> None:
+    my_outer_struct: outer_struct = outer_struct()
+
+    update_my_inner_struct(my_outer_struct.b)
+    assert my_outer_struct.b.a == 99999
+
+main()