Invalid c-code with nested struct initializer

I have a struct of structures which I can't initialize it this way

struct Foo {
	int i;
}

struct Bar {
	Foo a;
	Foo b;
}

void main () {
	Bar bar = { { 23 }, { 42 } };
}

test.vala.c: In function ‘_vala_main’:
test.vala.c:106:13: error: expected expression before ‘{’ token
  106 |  _tmp0_.a = {23};
      |             ^
test.vala.c:107:13: error: expected expression before ‘{’ token
  107 |  _tmp0_.b = {42};
      |             ^
error: cc exited with status 256