fix

vlib/builtin/array.v

@@ -189,6 +189,19 @@ pub fn (arr mut array) _push_many(val voidptr, size int) {
 	arr.len += size
 }
 
+pub fn (a array) reverse() array {
+	arr := array {
+		len: a.len
+		cap: a.cap
+		element_size: a.element_size
+		data: malloc(a.cap * a.element_size)
+	}
+	for i := 0; i < a.len; i++ {
+		C.memcpy(arr.data + i * arr.element_size, &a[a.len-1-i], arr.element_size)
+	}
+	return arr
+}
+
 pub fn (a []int) str() string {
 	mut res := '['
 	for i := 0; i < a.len; i++ {

vlib/builtin/array_test.v

@@ -148,4 +148,10 @@ fn test_push_many() {
 	assert a[5] == 6
 }
 
+fn test_reverse() {
+	mut a := [1, 2, 3, 4]
+	mut b := ['test', 'array', 'reverse']
 
+	assert a.reverse() == [4, 3, 2, 1]
+	assert b.reverse() == ['reverse', 'array', 'test']
+}