toml: fix custom to_toml for complex structs

vlib/toml/tests/encode_and_decode_test.v

@@ -121,6 +121,22 @@ title = 2'
 	assert y.title == .worker
 }
 
+struct Example {
+	array []Problem
+}
+
+struct Problem {
+}
+
+pub fn (example Example) to_toml() string {
+	return '[This is Valid]'
+}
+
+fn test_custom_encode_of_complex_struct() {
+	example := Example{}
+	assert toml.encode(example) == '[This is Valid]'
+}
+
 fn test_array_encode_decode() {
 	a := Arrs{
 		strs: ['foo', 'bar']

vlib/toml/toml.v

@@ -101,7 +101,17 @@ fn encode_struct[T](typ T) map[string]Any {
 		} $else $if field.is_array {
 			mut arr := []Any{}
 			for v in value {
-				arr << Any(v)
+				$if v is Date {
+					arr << Any(v)
+				} $else $if v is Time {
+					arr << Any(v)
+				} $else $if v is DateTime {
+					arr << Any(v)
+				} $else $if v is $struct {
+					arr << Any(encode_struct(v))
+				} $else {
+					arr << Any(v)
+				}
 			}
 			mp[field.name] = arr
 		} $else {