The following code:
```
[SimpleType]
public struct MyTest {
	int foo;
	int bar;
	public MyTest() {
		print ("Works!\n");
	}
}

public void main() {
	MyTest ();
}
```

produces:

```
/Users/pancake/prg/posixvala/tests/iface.vala.c:28:10: error: passing 'MyTest' (aka 'struct _MyTest') to parameter of incompatible type 'const void *'
        memset (self, 0, sizeof (MyTest));
                ^~~~
/usr/include/secure/_string.h:77:59: note: expanded from macro 'memset'
  __builtin___memset_chk (dest, val, len, __darwin_obsz0 (dest))
                                                          ^
/usr/include/secure/_common.h:38:55: note: expanded from macro '__darwin_obsz0'
#define __darwin_obsz0(object) __builtin_object_size (object, 0)
                                                      ^
/Users/pancake/prg/posixvala/tests/iface.vala.c:59:25: error: too few arguments to function call, single argument 'self' was not specified
        _tmp0_ = my_test_init ();
                 ~~~~~~~~~~~~  ^
/Users/pancake/prg/posixvala/tests/iface.vala.c:27:1: note: 'my_test_init' declared here
void my_test_init (MyTest self) {
^
2 errors generated.
```

That's because the constructor is wrongly defined as follows:

```
void my_test_init (MyTest self) {
        memset (self, 0, sizeof (MyTest));
        g_print ("Works!\n");
}

void _vala_main (void) {
        MyTest _tmp0_ = {0};
        _tmp0_ = my_test_init ();
}
```

The magic of [SimpleType] makes the struct to be returned by functions in the return value instead of an out parameter (mytestinit(&_tmp0_)). So looks like Vala is not honoring that attribute in the constructor.

Also, there's a destructor which calls g_free() and i bet that will produce a runtime crash. SimpleTypes shouldnt be freed because they live in the stack.