time: `-` operator overloading (#7259)

vlib/time/time.v

@@ -348,6 +348,13 @@ pub fn (t Time) str() string {
 	return t.format_ss()
 }
 
+// Time subtract using eperator overloading
+pub fn (lhs Time) -(rhs Time) Duration {
+	lhs_micro := lhs.unix * 1000 * 1000 + u64(lhs.microsecond)
+	rhs_micro := rhs.unix * 1000 * 1000 + u64(rhs.microsecond)
+	return (i64(lhs_micro) - i64(rhs_micro)) * microsecond
+}
+
 fn convert_ctime(t C.tm, microsecond int) Time {
 	return Time{
 		year: t.tm_year + 1900

vlib/time/time_test.v

@@ -164,6 +164,20 @@ fn test_str() {
 	assert '1980-07-11 21:23:42' == time_to_test.str()
 }
 
+fn test_subtract() {
+	d_seconds := 3
+	d_microseconds := 13
+	duration := d_seconds * time.second + d_microseconds * time.microsecond
+	t1 := time_to_test
+	t2 := time.unix2(int(t1.unix) + d_seconds, t1.microsecond + d_microseconds)
+	d1 := t2 - t1
+	d2 := t1 - t2
+	assert d1 > 0
+	assert d1 == duration
+	assert d2 < 0
+	assert d2 == -duration
+}
+
 // not optimal test but will find obvious bugs
 fn test_now() {
 	now := time.now()