From 8cf2f64d5e35dbc8ced383f88759e11d62052799 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Thu, 23 Apr 2026 20:48:46 +0300
Subject: [PATCH] time: fix time.Time is_zero method (fixes #24765)

---
 vlib/time/README.md   |  2 ++
 vlib/time/time.v      |  7 +++++++
 vlib/time/time_test.v | 12 ++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/vlib/time/README.md b/vlib/time/README.md
index ceea9a258..39a5ea9ef 100644
--- a/vlib/time/README.md
+++ b/vlib/time/README.md
@@ -66,6 +66,8 @@ fn parse_rfc3339(s string) !Time
 
 `time.new(...)` validates the provided fields before calculating the Unix timestamp.
 Omitted `month` and `day` values default to `1`, and out-of-range values panic.
+Use `t.is_zero()` to check whether a `time.Time` is still its zero value before formatting or
+serializing it.
 
 Another very useful feature of the `time` module is the stop watch,
 for when you want to measure short time periods, elapsed while you
diff --git a/vlib/time/time.v b/vlib/time/time.v
index 8d10f13eb..15017d10a 100644
--- a/vlib/time/time.v
+++ b/vlib/time/time.v
@@ -152,6 +152,13 @@ pub fn (t Time) local_unix() i64 {
 	return time_with_unix(t).unix
 }
 
+// is_zero returns true when `t` is the zero value of `time.Time`.
+@[inline]
+pub fn (t Time) is_zero() bool {
+	return t.unix == 0 && t.year == 0 && t.month == 0 && t.day == 0 && t.hour == 0 && t.minute == 0
+		&& t.second == 0 && t.nanosecond == 0 && !t.is_local
+}
+
 // unix_milli returns the UNIX time with millisecond resolution.
 @[inline]
 pub fn (t Time) unix_milli() i64 {
diff --git a/vlib/time/time_test.v b/vlib/time/time_test.v
index 44f7e4abd..14004c32b 100644
--- a/vlib/time/time_test.v
+++ b/vlib/time/time_test.v
@@ -516,4 +516,16 @@ fn test_pre_epoch_unix_calculation() {
 		day:   1
 	).unix() == -62135596800
 	assert time.parse_rfc3339('0001-01-01T00:00:00Z')!.unix() == -62135596800
+	assert t.is_zero()
+	// assert t.unix() == -62169984000
+	assert t.custom_format('MMMM YYYY') == 'January 0'
+}
+
+fn test_is_zero() {
+	assert time.Time{}.is_zero()
+	assert !time.unix(0).is_zero()
+	assert !time.new(year: 2024).is_zero()
+	assert !time.Time{
+		is_local: true
+	}.is_zero()
 }
-- 
2.39.5