array: fix array_clone (fix #8220) (#8238)

vlib/builtin/array.v

@@ -346,17 +346,25 @@ pub fn (a &array) clone() array {
 	// Recursively clone-generated elements if array element is array type
 	size_of_array := int(sizeof(array))
 	if a.element_size == size_of_array {
+		mut is_elem_array := true
 		for i in 0 .. a.len {
 			ar := array{}
 			unsafe { C.memcpy(&ar, a.get_unsafe(i), size_of_array) }
+			if ar.len > ar.cap || ar.cap <= 0 || ar.element_size <= 0 {
+				is_elem_array = false
+				break
+			}
 			ar_clone := ar.clone()
 			unsafe { arr.set_unsafe(i, &ar_clone) }
 		}
-	} else {
-		if !isnil(a.data) {
-			unsafe { C.memcpy(byteptr(arr.data), a.data, a.cap * a.element_size) }
+		if is_elem_array {
+			return arr
 		}
 	}
+
+	if !isnil(a.data) {
+		unsafe { C.memcpy(byteptr(arr.data), a.data, a.cap * a.element_size) }
+	}
 	return arr
 }
 

vlib/builtin/array_test.v

@@ -1343,3 +1343,19 @@ fn test_multi_fixed_array_with_default_init() {
 	println(a)
 	assert a == [[10, 10, 10]!, [10, 10, 10]!, [10, 10, 10]!]!
 }
+
+struct Abc {
+mut:
+	x i64
+	y i64
+	z i64
+}
+
+fn test_clone_of_same_elem_size_array() {
+	mut arr := []Abc{}
+	arr << Abc{1, 2, 3}
+	arr << Abc{2, 3, 4}
+	arr2 := arr.clone()
+	println(arr2)
+	assert arr2 == [Abc{1, 2, 3}, Abc{2, 3, 4}]
+}