sort: fix C compilation error for `fn abc(mut a []int) { a.sort() }`

vlib/builtin/sorting_test.v

@@ -0,0 +1,40 @@
+const (
+	unsorted = [2,30,10,20,1]
+	sorted_asc = [1, 2, 10, 20, 30]
+	sorted_desc = [30, 20, 10, 2, 1]
+)
+
+fn test_sorting_simple() {
+	mut a := unsorted
+	a.sort()
+	eprintln(' a: $a')
+	assert a == sorted_asc
+}
+
+fn test_sorting_with_condition_expression() {
+	mut a := unsorted
+	a.sort(a>b)
+	eprintln(' a: $a')
+	assert a == sorted_desc
+}
+
+
+fn mysort (mut a []int) {
+	a.sort()
+}
+
+fn test_sorting_by_passing_a_mut_array_to_a_function() {
+	mut a := unsorted
+	mysort(mut a)
+	eprintln(' a: $a')
+	assert a == sorted_asc
+}
+
+/*
+fn test_sorting_by_passing_an_anonymous_sorting_function() {
+	mut a := unsorted
+	a.sort(fn(a &int, b &int) int {	return *b - *a })
+	eprintln(' a: $a')
+	assert a == sort_desc
+}
+*/

vlib/v/gen/cgen.v

@@ -3997,13 +3997,15 @@ fn (mut g Gen) gen_array_sort(node ast.CallExpr) {
 		compare_fn += '_reverse'
 	}
 	//
+	deref := if node.left_type.is_ptr() || node.left_type.is_pointer() { '->' } else { '.' }
+	// eprintln('> qsort: pointer $node.left_type | deref: `$deref`')
 	g.write('qsort(')
 	g.expr(node.left)
-	g.write('.data, ')
+	g.write('${deref}data, ')
 	g.expr(node.left)
-	g.write('.len, ')
+	g.write('${deref}len, ')
 	g.expr(node.left)
-	g.writeln('.element_size, $compare_fn);')
+	g.writeln('${deref}element_size, $compare_fn);')
 }
 
 // `nums.filter(it % 2 == 0)`