Created attachment 179483 [details] [review]
qsort_with_data's CompareDataFunc takes pointers instead of the real values

Currently glib-2.0.vapi contains the following qsort_with_data definition:

private static void qsort_with_data<T> (T[] elems, size_t size, [CCode (type = "GCompareDataFunc")] GLib.CompareDataFunc<T> compare_func);

The problem is, that the CompareDataFunc does get a pointer to the actual value, thus the following statement would be correct:

private static void qsort_with_data<T> (T[] elems, size_t size, [CCode (type = "GCompareDataFunc")] GLib.CompareDataFunc<T*> compare_func);

You can see the problem in this example - currently you need to use it like this (you will get some gcc warnings, but the code sorts the array):

int compare(int a, int b) {
	return (*((int*) a) - *((int *)b)) < 0 ? -1 : 1;
}

void main() {
	int[] testdata = {5,4,3,2,1};
	qsort_with_data<int>(testdata, sizeof(int), compare );

	foreach(int i in testdata)
		stdout.printf("%d, ", i);
	stdout.printf("\n");
}

After changing the qsort_with_data in the vapi file you can do it like this:

int compare(int *a, int *b) {
	return (*a - *b) < 0 ? -1 : 1;
}

void main() {
	int[] testdata = {5,4,3,2,1};
	qsort_with_data<int>(testdata, sizeof(int), compare );

	foreach(int i in testdata)
		stdout.printf("%d, ", i);
	stdout.printf("\n");
}

Still remaining are some of the gcc warnings. I'm not sure were these needs to be fixed. They
are printed because of a missing typecast in the generated C code (gconstpointer to gint* in this
example).