Created attachment 177841 [details]
Generated C source

/*
The following peice of code generates a warning, but the code still works.
*/

delegate void MyDel (int a, string b);

static int main (string[] args) {

  int c = 10;

  MyDel myDel = (a,b) => {
    stdout.printf ("a:%d  b:%s  c:%d\n", a, b, c);
    c = 40;
  };

  myDel (5, "test");

  stdout.printf ("c:%d\n", c);

  return 0;
}

/*
When compiling it gives a warning, but it still runs
$ valac -o foo delegate-incompatible-pointer-warning.vala
/tmp/bug-test/delegate-incompatible-pointer-warning.vala.c: In function ‘_vala_main’:
/tmp/bug-test/delegate-incompatible-pointer-warning.vala.c:64:109: warning: assignment from incompatible pointer type

$ ./foo
a:5  b:test  c:10
c:40
*/

// Here are the relevant portions from the c output:
#if 0
static Block1Data* block1_data_ref (Block1Data* _data1_) {
	g_atomic_int_inc (&_data1_->_ref_count_);
	return _data1_;
}
// <snip>
	GDestroyNotify myDel_target_destroy_notify = NULL;
// <snip>
	myDel = (_tmp0_ = __lambda0__my_del, myDel_target = block1_data_ref (_data1_), myDel_target_destroy_notify = block1_data_unref, _tmp0_);

#endif

/*
If I cast block1_data_unref to GDestroyNotify the warning goes away
*/