Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

41 files changed, 12160 insertions, 0 deletions

diff --git a/src/time/embed.go b/src/time/embed.go
new file mode 100644
index 0000000..2a9821b
--- /dev/null
+++ b/src/time/embed.go
@@ -0,0 +1,12 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file is used with build tag timetzdata to embed tzdata into
+// the binary.
+
+//go:build timetzdata
+
+package time
+
+import _ "time/tzdata"
diff --git a/src/time/example_test.go b/src/time/example_test.go
new file mode 100644
index 0000000..059c631
--- /dev/null
+++ b/src/time/example_test.go
@@ -0,0 +1,725 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"fmt"
+	"time"
+)
+
+func expensiveCall() {}
+
+func ExampleDuration() {
+	t0 := time.Now()
+	expensiveCall()
+	t1 := time.Now()
+	fmt.Printf("The call took %v to run.\n", t1.Sub(t0))
+}
+
+func ExampleDuration_Round() {
+	d, err := time.ParseDuration("1h15m30.918273645s")
+	if err != nil {
+		panic(err)
+	}
+
+	round := []time.Duration{
+		time.Nanosecond,
+		time.Microsecond,
+		time.Millisecond,
+		time.Second,
+		2 * time.Second,
+		time.Minute,
+		10 * time.Minute,
+		time.Hour,
+	}
+
+	for _, r := range round {
+		fmt.Printf("d.Round(%6s) = %s\n", r, d.Round(r).String())
+	}
+	// Output:
+	// d.Round(   1ns) = 1h15m30.918273645s
+	// d.Round(   1µs) = 1h15m30.918274s
+	// d.Round(   1ms) = 1h15m30.918s
+	// d.Round(    1s) = 1h15m31s
+	// d.Round(    2s) = 1h15m30s
+	// d.Round(  1m0s) = 1h16m0s
+	// d.Round( 10m0s) = 1h20m0s
+	// d.Round(1h0m0s) = 1h0m0s
+}
+
+func ExampleDuration_String() {
+	fmt.Println(1*time.Hour + 2*time.Minute + 300*time.Millisecond)
+	fmt.Println(300 * time.Millisecond)
+	// Output:
+	// 1h2m0.3s
+	// 300ms
+}
+
+func ExampleDuration_Truncate() {
+	d, err := time.ParseDuration("1h15m30.918273645s")
+	if err != nil {
+		panic(err)
+	}
+
+	trunc := []time.Duration{
+		time.Nanosecond,
+		time.Microsecond,
+		time.Millisecond,
+		time.Second,
+		2 * time.Second,
+		time.Minute,
+		10 * time.Minute,
+		time.Hour,
+	}
+
+	for _, t := range trunc {
+		fmt.Printf("d.Truncate(%6s) = %s\n", t, d.Truncate(t).String())
+	}
+	// Output:
+	// d.Truncate(   1ns) = 1h15m30.918273645s
+	// d.Truncate(   1µs) = 1h15m30.918273s
+	// d.Truncate(   1ms) = 1h15m30.918s
+	// d.Truncate(    1s) = 1h15m30s
+	// d.Truncate(    2s) = 1h15m30s
+	// d.Truncate(  1m0s) = 1h15m0s
+	// d.Truncate( 10m0s) = 1h10m0s
+	// d.Truncate(1h0m0s) = 1h0m0s
+}
+
+func ExampleParseDuration() {
+	hours, _ := time.ParseDuration("10h")
+	complex, _ := time.ParseDuration("1h10m10s")
+	micro, _ := time.ParseDuration("1µs")
+	// The package also accepts the incorrect but common prefix u for micro.
+	micro2, _ := time.ParseDuration("1us")
+
+	fmt.Println(hours)
+	fmt.Println(complex)
+	fmt.Printf("There are %.0f seconds in %v.\n", complex.Seconds(), complex)
+	fmt.Printf("There are %d nanoseconds in %v.\n", micro.Nanoseconds(), micro)
+	fmt.Printf("There are %6.2e seconds in %v.\n", micro2.Seconds(), micro)
+	// Output:
+	// 10h0m0s
+	// 1h10m10s
+	// There are 4210 seconds in 1h10m10s.
+	// There are 1000 nanoseconds in 1µs.
+	// There are 1.00e-06 seconds in 1µs.
+}
+
+func ExampleDuration_Hours() {
+	h, _ := time.ParseDuration("4h30m")
+	fmt.Printf("I've got %.1f hours of work left.", h.Hours())
+	// Output: I've got 4.5 hours of work left.
+}
+
+func ExampleDuration_Microseconds() {
+	u, _ := time.ParseDuration("1s")
+	fmt.Printf("One second is %d microseconds.\n", u.Microseconds())
+	// Output:
+	// One second is 1000000 microseconds.
+}
+
+func ExampleDuration_Milliseconds() {
+	u, _ := time.ParseDuration("1s")
+	fmt.Printf("One second is %d milliseconds.\n", u.Milliseconds())
+	// Output:
+	// One second is 1000 milliseconds.
+}
+
+func ExampleDuration_Minutes() {
+	m, _ := time.ParseDuration("1h30m")
+	fmt.Printf("The movie is %.0f minutes long.", m.Minutes())
+	// Output: The movie is 90 minutes long.
+}
+
+func ExampleDuration_Nanoseconds() {
+	u, _ := time.ParseDuration("1µs")
+	fmt.Printf("One microsecond is %d nanoseconds.\n", u.Nanoseconds())
+	// Output:
+	// One microsecond is 1000 nanoseconds.
+}
+
+func ExampleDuration_Seconds() {
+	m, _ := time.ParseDuration("1m30s")
+	fmt.Printf("Take off in t-%.0f seconds.", m.Seconds())
+	// Output: Take off in t-90 seconds.
+}
+
+var c chan int
+
+func handle(int) {}
+
+func ExampleAfter() {
+	select {
+	case m := <-c:
+		handle(m)
+	case <-time.After(10 * time.Second):
+		fmt.Println("timed out")
+	}
+}
+
+func ExampleSleep() {
+	time.Sleep(100 * time.Millisecond)
+}
+
+func statusUpdate() string { return "" }
+
+func ExampleTick() {
+	c := time.Tick(5 * time.Second)
+	for next := range c {
+		fmt.Printf("%v %s\n", next, statusUpdate())
+	}
+}
+
+func ExampleMonth() {
+	_, month, day := time.Now().Date()
+	if month == time.November && day == 10 {
+		fmt.Println("Happy Go day!")
+	}
+}
+
+func ExampleDate() {
+	t := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
+	fmt.Printf("Go launched at %s\n", t.Local())
+	// Output: Go launched at 2009-11-10 15:00:00 -0800 PST
+}
+
+func ExampleNewTicker() {
+	ticker := time.NewTicker(time.Second)
+	defer ticker.Stop()
+	done := make(chan bool)
+	go func() {
+		time.Sleep(10 * time.Second)
+		done <- true
+	}()
+	for {
+		select {
+		case <-done:
+			fmt.Println("Done!")
+			return
+		case t := <-ticker.C:
+			fmt.Println("Current time: ", t)
+		}
+	}
+}
+
+func ExampleTime_Format() {
+	// Parse a time value from a string in the standard Unix format.
+	t, err := time.Parse(time.UnixDate, "Wed Feb 25 11:06:39 PST 2015")
+	if err != nil { // Always check errors even if they should not happen.
+		panic(err)
+	}
+
+	tz, err := time.LoadLocation("Asia/Shanghai")
+	if err != nil { // Always check errors even if they should not happen.
+		panic(err)
+	}
+
+	// time.Time's Stringer method is useful without any format.
+	fmt.Println("default format:", t)
+
+	// Predefined constants in the package implement common layouts.
+	fmt.Println("Unix format:", t.Format(time.UnixDate))
+
+	// The time zone attached to the time value affects its output.
+	fmt.Println("Same, in UTC:", t.UTC().Format(time.UnixDate))
+
+	fmt.Println("in Shanghai with seconds:", t.In(tz).Format("2006-01-02T15:04:05 -070000"))
+
+	fmt.Println("in Shanghai with colon seconds:", t.In(tz).Format("2006-01-02T15:04:05 -07:00:00"))
+
+	// The rest of this function demonstrates the properties of the
+	// layout string used in the format.
+
+	// The layout string used by the Parse function and Format method
+	// shows by example how the reference time should be represented.
+	// We stress that one must show how the reference time is formatted,
+	// not a time of the user's choosing. Thus each layout string is a
+	// representation of the time stamp,
+	//	Jan 2 15:04:05 2006 MST
+	// An easy way to remember this value is that it holds, when presented
+	// in this order, the values (lined up with the elements above):
+	//	  1 2  3  4  5    6  -7
+	// There are some wrinkles illustrated below.
+
+	// Most uses of Format and Parse use constant layout strings such as
+	// the ones defined in this package, but the interface is flexible,
+	// as these examples show.
+
+	// Define a helper function to make the examples' output look nice.
+	do := func(name, layout, want string) {
+		got := t.Format(layout)
+		if want != got {
+			fmt.Printf("error: for %q got %q; expected %q\n", layout, got, want)
+			return
+		}
+		fmt.Printf("%-16s %q gives %q\n", name, layout, got)
+	}
+
+	// Print a header in our output.
+	fmt.Printf("\nFormats:\n\n")
+
+	// Simple starter examples.
+	do("Basic full date", "Mon Jan 2 15:04:05 MST 2006", "Wed Feb 25 11:06:39 PST 2015")
+	do("Basic short date", "2006/01/02", "2015/02/25")
+
+	// The hour of the reference time is 15, or 3PM. The layout can express
+	// it either way, and since our value is the morning we should see it as
+	// an AM time. We show both in one format string. Lower case too.
+	do("AM/PM", "3PM==3pm==15h", "11AM==11am==11h")
+
+	// When parsing, if the seconds value is followed by a decimal point
+	// and some digits, that is taken as a fraction of a second even if
+	// the layout string does not represent the fractional second.
+	// Here we add a fractional second to our time value used above.
+	t, err = time.Parse(time.UnixDate, "Wed Feb 25 11:06:39.1234 PST 2015")
+	if err != nil {
+		panic(err)
+	}
+	// It does not appear in the output if the layout string does not contain
+	// a representation of the fractional second.
+	do("No fraction", time.UnixDate, "Wed Feb 25 11:06:39 PST 2015")
+
+	// Fractional seconds can be printed by adding a run of 0s or 9s after
+	// a decimal point in the seconds value in the layout string.
+	// If the layout digits are 0s, the fractional second is of the specified
+	// width. Note that the output has a trailing zero.
+	do("0s for fraction", "15:04:05.00000", "11:06:39.12340")
+
+	// If the fraction in the layout is 9s, trailing zeros are dropped.
+	do("9s for fraction", "15:04:05.99999999", "11:06:39.1234")
+
+	// Output:
+	// default format: 2015-02-25 11:06:39 -0800 PST
+	// Unix format: Wed Feb 25 11:06:39 PST 2015
+	// Same, in UTC: Wed Feb 25 19:06:39 UTC 2015
+	//in Shanghai with seconds: 2015-02-26T03:06:39 +080000
+	//in Shanghai with colon seconds: 2015-02-26T03:06:39 +08:00:00
+	//
+	// Formats:
+	//
+	// Basic full date  "Mon Jan 2 15:04:05 MST 2006" gives "Wed Feb 25 11:06:39 PST 2015"
+	// Basic short date "2006/01/02" gives "2015/02/25"
+	// AM/PM            "3PM==3pm==15h" gives "11AM==11am==11h"
+	// No fraction      "Mon Jan _2 15:04:05 MST 2006" gives "Wed Feb 25 11:06:39 PST 2015"
+	// 0s for fraction  "15:04:05.00000" gives "11:06:39.12340"
+	// 9s for fraction  "15:04:05.99999999" gives "11:06:39.1234"
+
+}
+
+func ExampleTime_Format_pad() {
+	// Parse a time value from a string in the standard Unix format.
+	t, err := time.Parse(time.UnixDate, "Sat Mar 7 11:06:39 PST 2015")
+	if err != nil { // Always check errors even if they should not happen.
+		panic(err)
+	}
+
+	// Define a helper function to make the examples' output look nice.
+	do := func(name, layout, want string) {
+		got := t.Format(layout)
+		if want != got {
+			fmt.Printf("error: for %q got %q; expected %q\n", layout, got, want)
+			return
+		}
+		fmt.Printf("%-16s %q gives %q\n", name, layout, got)
+	}
+
+	// The predefined constant Unix uses an underscore to pad the day.
+	do("Unix", time.UnixDate, "Sat Mar  7 11:06:39 PST 2015")
+
+	// For fixed-width printing of values, such as the date, that may be one or
+	// two characters (7 vs. 07), use an _ instead of a space in the layout string.
+	// Here we print just the day, which is 2 in our layout string and 7 in our
+	// value.
+	do("No pad", "<2>", "<7>")
+
+	// An underscore represents a space pad, if the date only has one digit.
+	do("Spaces", "<_2>", "< 7>")
+
+	// A "0" indicates zero padding for single-digit values.
+	do("Zeros", "<02>", "<07>")
+
+	// If the value is already the right width, padding is not used.
+	// For instance, the second (05 in the reference time) in our value is 39,
+	// so it doesn't need padding, but the minutes (04, 06) does.
+	do("Suppressed pad", "04:05", "06:39")
+
+	// Output:
+	// Unix             "Mon Jan _2 15:04:05 MST 2006" gives "Sat Mar  7 11:06:39 PST 2015"
+	// No pad           "<2>" gives "<7>"
+	// Spaces           "<_2>" gives "< 7>"
+	// Zeros            "<02>" gives "<07>"
+	// Suppressed pad   "04:05" gives "06:39"
+
+}
+
+func ExampleTime_GoString() {
+	t := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
+	fmt.Println(t.GoString())
+	t = t.Add(1 * time.Minute)
+	fmt.Println(t.GoString())
+	t = t.AddDate(0, 1, 0)
+	fmt.Println(t.GoString())
+	t, _ = time.Parse("Jan 2, 2006 at 3:04pm (MST)", "Feb 3, 2013 at 7:54pm (UTC)")
+	fmt.Println(t.GoString())
+
+	// Output:
+	// time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
+	// time.Date(2009, time.November, 10, 23, 1, 0, 0, time.UTC)
+	// time.Date(2009, time.December, 10, 23, 1, 0, 0, time.UTC)
+	// time.Date(2013, time.February, 3, 19, 54, 0, 0, time.UTC)
+}
+
+func ExampleParse() {
+	// See the example for Time.Format for a thorough description of how
+	// to define the layout string to parse a time.Time value; Parse and
+	// Format use the same model to describe their input and output.
+
+	// longForm shows by example how the reference time would be represented in
+	// the desired layout.
+	const longForm = "Jan 2, 2006 at 3:04pm (MST)"
+	t, _ := time.Parse(longForm, "Feb 3, 2013 at 7:54pm (PST)")
+	fmt.Println(t)
+
+	// shortForm is another way the reference time would be represented
+	// in the desired layout; it has no time zone present.
+	// Note: without explicit zone, returns time in UTC.
+	const shortForm = "2006-Jan-02"
+	t, _ = time.Parse(shortForm, "2013-Feb-03")
+	fmt.Println(t)
+
+	// Some valid layouts are invalid time values, due to format specifiers
+	// such as _ for space padding and Z for zone information.
+	// For example the RFC3339 layout 2006-01-02T15:04:05Z07:00
+	// contains both Z and a time zone offset in order to handle both valid options:
+	// 2006-01-02T15:04:05Z
+	// 2006-01-02T15:04:05+07:00
+	t, _ = time.Parse(time.RFC3339, "2006-01-02T15:04:05Z")
+	fmt.Println(t)
+	t, _ = time.Parse(time.RFC3339, "2006-01-02T15:04:05+07:00")
+	fmt.Println(t)
+	_, err := time.Parse(time.RFC3339, time.RFC3339)
+	fmt.Println("error", err) // Returns an error as the layout is not a valid time value
+
+	// Output:
+	// 2013-02-03 19:54:00 -0800 PST
+	// 2013-02-03 00:00:00 +0000 UTC
+	// 2006-01-02 15:04:05 +0000 UTC
+	// 2006-01-02 15:04:05 +0700 +0700
+	// error parsing time "2006-01-02T15:04:05Z07:00": extra text: "07:00"
+}
+
+func ExampleParseInLocation() {
+	loc, _ := time.LoadLocation("Europe/Berlin")
+
+	// This will look for the name CEST in the Europe/Berlin time zone.
+	const longForm = "Jan 2, 2006 at 3:04pm (MST)"
+	t, _ := time.ParseInLocation(longForm, "Jul 9, 2012 at 5:02am (CEST)", loc)
+	fmt.Println(t)
+
+	// Note: without explicit zone, returns time in given location.
+	const shortForm = "2006-Jan-02"
+	t, _ = time.ParseInLocation(shortForm, "2012-Jul-09", loc)
+	fmt.Println(t)
+
+	// Output:
+	// 2012-07-09 05:02:00 +0200 CEST
+	// 2012-07-09 00:00:00 +0200 CEST
+}
+
+func ExampleUnix() {
+	unixTime := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
+	fmt.Println(unixTime.Unix())
+	t := time.Unix(unixTime.Unix(), 0).UTC()
+	fmt.Println(t)
+
+	// Output:
+	// 1257894000
+	// 2009-11-10 23:00:00 +0000 UTC
+}
+
+func ExampleUnixMicro() {
+	umt := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
+	fmt.Println(umt.UnixMicro())
+	t := time.UnixMicro(umt.UnixMicro()).UTC()
+	fmt.Println(t)
+
+	// Output:
+	// 1257894000000000
+	// 2009-11-10 23:00:00 +0000 UTC
+}
+
+func ExampleUnixMilli() {
+	umt := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
+	fmt.Println(umt.UnixMilli())
+	t := time.UnixMilli(umt.UnixMilli()).UTC()
+	fmt.Println(t)
+
+	// Output:
+	// 1257894000000
+	// 2009-11-10 23:00:00 +0000 UTC
+}
+
+func ExampleTime_Unix() {
+	// 1 billion seconds of Unix, three ways.
+	fmt.Println(time.Unix(1e9, 0).UTC())     // 1e9 seconds
+	fmt.Println(time.Unix(0, 1e18).UTC())    // 1e18 nanoseconds
+	fmt.Println(time.Unix(2e9, -1e18).UTC()) // 2e9 seconds - 1e18 nanoseconds
+
+	t := time.Date(2001, time.September, 9, 1, 46, 40, 0, time.UTC)
+	fmt.Println(t.Unix())     // seconds since 1970
+	fmt.Println(t.UnixNano()) // nanoseconds since 1970
+
+	// Output:
+	// 2001-09-09 01:46:40 +0000 UTC
+	// 2001-09-09 01:46:40 +0000 UTC
+	// 2001-09-09 01:46:40 +0000 UTC
+	// 1000000000
+	// 1000000000000000000
+}
+
+func ExampleTime_Round() {
+	t := time.Date(0, 0, 0, 12, 15, 30, 918273645, time.UTC)
+	round := []time.Duration{
+		time.Nanosecond,
+		time.Microsecond,
+		time.Millisecond,
+		time.Second,
+		2 * time.Second,
+		time.Minute,
+		10 * time.Minute,
+		time.Hour,
+	}
+
+	for _, d := range round {
+		fmt.Printf("t.Round(%6s) = %s\n", d, t.Round(d).Format("15:04:05.999999999"))
+	}
+	// Output:
+	// t.Round(   1ns) = 12:15:30.918273645
+	// t.Round(   1µs) = 12:15:30.918274
+	// t.Round(   1ms) = 12:15:30.918
+	// t.Round(    1s) = 12:15:31
+	// t.Round(    2s) = 12:15:30
+	// t.Round(  1m0s) = 12:16:00
+	// t.Round( 10m0s) = 12:20:00
+	// t.Round(1h0m0s) = 12:00:00
+}
+
+func ExampleTime_Truncate() {
+	t, _ := time.Parse("2006 Jan 02 15:04:05", "2012 Dec 07 12:15:30.918273645")
+	trunc := []time.Duration{
+		time.Nanosecond,
+		time.Microsecond,
+		time.Millisecond,
+		time.Second,
+		2 * time.Second,
+		time.Minute,
+		10 * time.Minute,
+	}
+
+	for _, d := range trunc {
+		fmt.Printf("t.Truncate(%5s) = %s\n", d, t.Truncate(d).Format("15:04:05.999999999"))
+	}
+	// To round to the last midnight in the local timezone, create a new Date.
+	midnight := time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, time.Local)
+	_ = midnight
+
+	// Output:
+	// t.Truncate(  1ns) = 12:15:30.918273645
+	// t.Truncate(  1µs) = 12:15:30.918273
+	// t.Truncate(  1ms) = 12:15:30.918
+	// t.Truncate(   1s) = 12:15:30
+	// t.Truncate(   2s) = 12:15:30
+	// t.Truncate( 1m0s) = 12:15:00
+	// t.Truncate(10m0s) = 12:10:00
+}
+
+func ExampleLoadLocation() {
+	location, err := time.LoadLocation("America/Los_Angeles")
+	if err != nil {
+		panic(err)
+	}
+
+	timeInUTC := time.Date(2018, 8, 30, 12, 0, 0, 0, time.UTC)
+	fmt.Println(timeInUTC.In(location))
+	// Output: 2018-08-30 05:00:00 -0700 PDT
+}
+
+func ExampleLocation() {
+	// China doesn't have daylight saving. It uses a fixed 8 hour offset from UTC.
+	secondsEastOfUTC := int((8 * time.Hour).Seconds())
+	beijing := time.FixedZone("Beijing Time", secondsEastOfUTC)
+
+	// If the system has a timezone database present, it's possible to load a location
+	// from that, e.g.:
+	//    newYork, err := time.LoadLocation("America/New_York")
+
+	// Creating a time requires a location. Common locations are time.Local and time.UTC.
+	timeInUTC := time.Date(2009, 1, 1, 12, 0, 0, 0, time.UTC)
+	sameTimeInBeijing := time.Date(2009, 1, 1, 20, 0, 0, 0, beijing)
+
+	// Although the UTC clock time is 1200 and the Beijing clock time is 2000, Beijing is
+	// 8 hours ahead so the two dates actually represent the same instant.
+	timesAreEqual := timeInUTC.Equal(sameTimeInBeijing)
+	fmt.Println(timesAreEqual)
+
+	// Output:
+	// true
+}
+
+func ExampleTime_Add() {
+	start := time.Date(2009, 1, 1, 12, 0, 0, 0, time.UTC)
+	afterTenSeconds := start.Add(time.Second * 10)
+	afterTenMinutes := start.Add(time.Minute * 10)
+	afterTenHours := start.Add(time.Hour * 10)
+	afterTenDays := start.Add(time.Hour * 24 * 10)
+
+	fmt.Printf("start = %v\n", start)
+	fmt.Printf("start.Add(time.Second * 10) = %v\n", afterTenSeconds)
+	fmt.Printf("start.Add(time.Minute * 10) = %v\n", afterTenMinutes)
+	fmt.Printf("start.Add(time.Hour * 10) = %v\n", afterTenHours)
+	fmt.Printf("start.Add(time.Hour * 24 * 10) = %v\n", afterTenDays)
+
+	// Output:
+	// start = 2009-01-01 12:00:00 +0000 UTC
+	// start.Add(time.Second * 10) = 2009-01-01 12:00:10 +0000 UTC
+	// start.Add(time.Minute * 10) = 2009-01-01 12:10:00 +0000 UTC
+	// start.Add(time.Hour * 10) = 2009-01-01 22:00:00 +0000 UTC
+	// start.Add(time.Hour * 24 * 10) = 2009-01-11 12:00:00 +0000 UTC
+}
+
+func ExampleTime_AddDate() {
+	start := time.Date(2009, 1, 1, 0, 0, 0, 0, time.UTC)
+	oneDayLater := start.AddDate(0, 0, 1)
+	oneMonthLater := start.AddDate(0, 1, 0)
+	oneYearLater := start.AddDate(1, 0, 0)
+
+	fmt.Printf("oneDayLater: start.AddDate(0, 0, 1) = %v\n", oneDayLater)
+	fmt.Printf("oneMonthLater: start.AddDate(0, 1, 0) = %v\n", oneMonthLater)
+	fmt.Printf("oneYearLater: start.AddDate(1, 0, 0) = %v\n", oneYearLater)
+
+	// Output:
+	// oneDayLater: start.AddDate(0, 0, 1) = 2009-01-02 00:00:00 +0000 UTC
+	// oneMonthLater: start.AddDate(0, 1, 0) = 2009-02-01 00:00:00 +0000 UTC
+	// oneYearLater: start.AddDate(1, 0, 0) = 2010-01-01 00:00:00 +0000 UTC
+}
+
+func ExampleTime_After() {
+	year2000 := time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC)
+	year3000 := time.Date(3000, 1, 1, 0, 0, 0, 0, time.UTC)
+
+	isYear3000AfterYear2000 := year3000.After(year2000) // True
+	isYear2000AfterYear3000 := year2000.After(year3000) // False
+
+	fmt.Printf("year3000.After(year2000) = %v\n", isYear3000AfterYear2000)
+	fmt.Printf("year2000.After(year3000) = %v\n", isYear2000AfterYear3000)
+
+	// Output:
+	// year3000.After(year2000) = true
+	// year2000.After(year3000) = false
+}
+
+func ExampleTime_Before() {
+	year2000 := time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC)
+	year3000 := time.Date(3000, 1, 1, 0, 0, 0, 0, time.UTC)
+
+	isYear2000BeforeYear3000 := year2000.Before(year3000) // True
+	isYear3000BeforeYear2000 := year3000.Before(year2000) // False
+
+	fmt.Printf("year2000.Before(year3000) = %v\n", isYear2000BeforeYear3000)
+	fmt.Printf("year3000.Before(year2000) = %v\n", isYear3000BeforeYear2000)
+
+	// Output:
+	// year2000.Before(year3000) = true
+	// year3000.Before(year2000) = false
+}
+
+func ExampleTime_Date() {
+	d := time.Date(2000, 2, 1, 12, 30, 0, 0, time.UTC)
+	year, month, day := d.Date()
+
+	fmt.Printf("year = %v\n", year)
+	fmt.Printf("month = %v\n", month)
+	fmt.Printf("day = %v\n", day)
+
+	// Output:
+	// year = 2000
+	// month = February
+	// day = 1
+}
+
+func ExampleTime_Day() {
+	d := time.Date(2000, 2, 1, 12, 30, 0, 0, time.UTC)
+	day := d.Day()
+
+	fmt.Printf("day = %v\n", day)
+
+	// Output:
+	// day = 1
+}
+
+func ExampleTime_Equal() {
+	secondsEastOfUTC := int((8 * time.Hour).Seconds())
+	beijing := time.FixedZone("Beijing Time", secondsEastOfUTC)
+
+	// Unlike the equal operator, Equal is aware that d1 and d2 are the
+	// same instant but in different time zones.
+	d1 := time.Date(2000, 2, 1, 12, 30, 0, 0, time.UTC)
+	d2 := time.Date(2000, 2, 1, 20, 30, 0, 0, beijing)
+
+	datesEqualUsingEqualOperator := d1 == d2
+	datesEqualUsingFunction := d1.Equal(d2)
+
+	fmt.Printf("datesEqualUsingEqualOperator = %v\n", datesEqualUsingEqualOperator)
+	fmt.Printf("datesEqualUsingFunction = %v\n", datesEqualUsingFunction)
+
+	// Output:
+	// datesEqualUsingEqualOperator = false
+	// datesEqualUsingFunction = true
+}
+
+func ExampleTime_String() {
+	timeWithNanoseconds := time.Date(2000, 2, 1, 12, 13, 14, 15, time.UTC)
+	withNanoseconds := timeWithNanoseconds.String()
+
+	timeWithoutNanoseconds := time.Date(2000, 2, 1, 12, 13, 14, 0, time.UTC)
+	withoutNanoseconds := timeWithoutNanoseconds.String()
+
+	fmt.Printf("withNanoseconds = %v\n", string(withNanoseconds))
+	fmt.Printf("withoutNanoseconds = %v\n", string(withoutNanoseconds))
+
+	// Output:
+	// withNanoseconds = 2000-02-01 12:13:14.000000015 +0000 UTC
+	// withoutNanoseconds = 2000-02-01 12:13:14 +0000 UTC
+}
+
+func ExampleTime_Sub() {
+	start := time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC)
+	end := time.Date(2000, 1, 1, 12, 0, 0, 0, time.UTC)
+
+	difference := end.Sub(start)
+	fmt.Printf("difference = %v\n", difference)
+
+	// Output:
+	// difference = 12h0m0s
+}
+
+func ExampleTime_AppendFormat() {
+	t := time.Date(2017, time.November, 4, 11, 0, 0, 0, time.UTC)
+	text := []byte("Time: ")
+
+	text = t.AppendFormat(text, time.Kitchen)
+	fmt.Println(string(text))
+
+	// Output:
+	// Time: 11:00AM
+}
+
+func ExampleFixedZone() {
+	loc := time.FixedZone("UTC-8", -8*60*60)
+	t := time.Date(2009, time.November, 10, 23, 0, 0, 0, loc)
+	fmt.Println("The time is:", t.Format(time.RFC822))
+	// Output: The time is: 10 Nov 09 23:00 UTC-8
+}
diff --git a/src/time/export_android_test.go b/src/time/export_android_test.go
new file mode 100644
index 0000000..17e0219
--- /dev/null
+++ b/src/time/export_android_test.go
@@ -0,0 +1,16 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+func ForceAndroidTzdataForTest() (undo func()) {
+	allowGorootSource = false
+	origLoadFromEmbeddedTZData := loadFromEmbeddedTZData
+	loadFromEmbeddedTZData = nil
+
+	return func() {
+		allowGorootSource = true
+		loadFromEmbeddedTZData = origLoadFromEmbeddedTZData
+	}
+}
diff --git a/src/time/export_test.go b/src/time/export_test.go
new file mode 100644
index 0000000..a4940d1
--- /dev/null
+++ b/src/time/export_test.go
@@ -0,0 +1,140 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+import (
+	"sync"
+)
+
+func ResetLocalOnceForTest() {
+	localOnce = sync.Once{}
+	localLoc = Location{}
+}
+
+func ForceUSPacificForTesting() {
+	ResetLocalOnceForTest()
+	localOnce.Do(initTestingZone)
+}
+
+func ZoneinfoForTesting() *string {
+	return zoneinfo
+}
+
+func ResetZoneinfoForTesting() {
+	zoneinfo = nil
+	zoneinfoOnce = sync.Once{}
+}
+
+var (
+	DisablePlatformSources = disablePlatformSources
+	GorootZoneSource       = gorootZoneSource
+	ParseTimeZone          = parseTimeZone
+	SetMono                = (*Time).setMono
+	GetMono                = (*Time).mono
+	ErrLocation            = errLocation
+	ReadFile               = readFile
+	LoadTzinfo             = loadTzinfo
+	NextStdChunk           = nextStdChunk
+	Tzset                  = tzset
+	TzsetName              = tzsetName
+	TzsetOffset            = tzsetOffset
+)
+
+func LoadFromEmbeddedTZData(zone string) (string, error) {
+	return loadFromEmbeddedTZData(zone)
+}
+
+type RuleKind int
+
+const (
+	RuleJulian       = RuleKind(ruleJulian)
+	RuleDOY          = RuleKind(ruleDOY)
+	RuleMonthWeekDay = RuleKind(ruleMonthWeekDay)
+	UnixToInternal   = unixToInternal
+)
+
+type Rule struct {
+	Kind RuleKind
+	Day  int
+	Week int
+	Mon  int
+	Time int
+}
+
+func TzsetRule(s string) (Rule, string, bool) {
+	r, rs, ok := tzsetRule(s)
+	rr := Rule{
+		Kind: RuleKind(r.kind),
+		Day:  r.day,
+		Week: r.week,
+		Mon:  r.mon,
+		Time: r.time,
+	}
+	return rr, rs, ok
+}
+
+// StdChunkNames maps from nextStdChunk results to the matched strings.
+var StdChunkNames = map[int]string{
+	0:                               "",
+	stdLongMonth:                    "January",
+	stdMonth:                        "Jan",
+	stdNumMonth:                     "1",
+	stdZeroMonth:                    "01",
+	stdLongWeekDay:                  "Monday",
+	stdWeekDay:                      "Mon",
+	stdDay:                          "2",
+	stdUnderDay:                     "_2",
+	stdZeroDay:                      "02",
+	stdUnderYearDay:                 "__2",
+	stdZeroYearDay:                  "002",
+	stdHour:                         "15",
+	stdHour12:                       "3",
+	stdZeroHour12:                   "03",
+	stdMinute:                       "4",
+	stdZeroMinute:                   "04",
+	stdSecond:                       "5",
+	stdZeroSecond:                   "05",
+	stdLongYear:                     "2006",
+	stdYear:                         "06",
+	stdPM:                           "PM",
+	stdpm:                           "pm",
+	stdTZ:                           "MST",
+	stdISO8601TZ:                    "Z0700",
+	stdISO8601SecondsTZ:             "Z070000",
+	stdISO8601ShortTZ:               "Z07",
+	stdISO8601ColonTZ:               "Z07:00",
+	stdISO8601ColonSecondsTZ:        "Z07:00:00",
+	stdNumTZ:                        "-0700",
+	stdNumSecondsTz:                 "-070000",
+	stdNumShortTZ:                   "-07",
+	stdNumColonTZ:                   "-07:00",
+	stdNumColonSecondsTZ:            "-07:00:00",
+	stdFracSecond0 | 1<<stdArgShift: ".0",
+	stdFracSecond0 | 2<<stdArgShift: ".00",
+	stdFracSecond0 | 3<<stdArgShift: ".000",
+	stdFracSecond0 | 4<<stdArgShift: ".0000",
+	stdFracSecond0 | 5<<stdArgShift: ".00000",
+	stdFracSecond0 | 6<<stdArgShift: ".000000",
+	stdFracSecond0 | 7<<stdArgShift: ".0000000",
+	stdFracSecond0 | 8<<stdArgShift: ".00000000",
+	stdFracSecond0 | 9<<stdArgShift: ".000000000",
+	stdFracSecond9 | 1<<stdArgShift: ".9",
+	stdFracSecond9 | 2<<stdArgShift: ".99",
+	stdFracSecond9 | 3<<stdArgShift: ".999",
+	stdFracSecond9 | 4<<stdArgShift: ".9999",
+	stdFracSecond9 | 5<<stdArgShift: ".99999",
+	stdFracSecond9 | 6<<stdArgShift: ".999999",
+	stdFracSecond9 | 7<<stdArgShift: ".9999999",
+	stdFracSecond9 | 8<<stdArgShift: ".99999999",
+	stdFracSecond9 | 9<<stdArgShift: ".999999999",
+}
+
+var Quote = quote
+
+var AppendInt = appendInt
+var AppendFormatAny = Time.appendFormat
+var AppendFormatRFC3339 = Time.appendFormatRFC3339
+var ParseAny = parse
+var ParseRFC3339 = parseRFC3339[string]
diff --git a/src/time/export_windows_test.go b/src/time/export_windows_test.go
new file mode 100644
index 0000000..cc9d6dd
--- /dev/null
+++ b/src/time/export_windows_test.go
@@ -0,0 +1,19 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+func ForceAusFromTZIForTesting() {
+	ResetLocalOnceForTest()
+	localOnce.Do(func() { initLocalFromTZI(&aus) })
+}
+
+func ForceUSPacificFromTZIForTesting() {
+	ResetLocalOnceForTest()
+	localOnce.Do(func() { initLocalFromTZI(&usPacific) })
+}
+
+func ToEnglishName(stdname, dstname string) (string, error) {
+	return toEnglishName(stdname, dstname)
+}
diff --git a/src/time/format.go b/src/time/format.go
new file mode 100644
index 0000000..7fbeddb
--- /dev/null
+++ b/src/time/format.go
@@ -0,0 +1,1686 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+import "errors"
+
+// These are predefined layouts for use in Time.Format and time.Parse.
+// The reference time used in these layouts is the specific time stamp:
+//
+//	01/02 03:04:05PM '06 -0700
+//
+// (January 2, 15:04:05, 2006, in time zone seven hours west of GMT).
+// That value is recorded as the constant named Layout, listed below. As a Unix
+// time, this is 1136239445. Since MST is GMT-0700, the reference would be
+// printed by the Unix date command as:
+//
+//	Mon Jan 2 15:04:05 MST 2006
+//
+// It is a regrettable historic error that the date uses the American convention
+// of putting the numerical month before the day.
+//
+// The example for Time.Format demonstrates the working of the layout string
+// in detail and is a good reference.
+//
+// Note that the RFC822, RFC850, and RFC1123 formats should be applied
+// only to local times. Applying them to UTC times will use "UTC" as the
+// time zone abbreviation, while strictly speaking those RFCs require the
+// use of "GMT" in that case.
+// In general RFC1123Z should be used instead of RFC1123 for servers
+// that insist on that format, and RFC3339 should be preferred for new protocols.
+// RFC3339, RFC822, RFC822Z, RFC1123, and RFC1123Z are useful for formatting;
+// when used with time.Parse they do not accept all the time formats
+// permitted by the RFCs and they do accept time formats not formally defined.
+// The RFC3339Nano format removes trailing zeros from the seconds field
+// and thus may not sort correctly once formatted.
+//
+// Most programs can use one of the defined constants as the layout passed to
+// Format or Parse. The rest of this comment can be ignored unless you are
+// creating a custom layout string.
+//
+// To define your own format, write down what the reference time would look like
+// formatted your way; see the values of constants like ANSIC, StampMicro or
+// Kitchen for examples. The model is to demonstrate what the reference time
+// looks like so that the Format and Parse methods can apply the same
+// transformation to a general time value.
+//
+// Here is a summary of the components of a layout string. Each element shows by
+// example the formatting of an element of the reference time. Only these values
+// are recognized. Text in the layout string that is not recognized as part of
+// the reference time is echoed verbatim during Format and expected to appear
+// verbatim in the input to Parse.
+//
+//	Year: "2006" "06"
+//	Month: "Jan" "January" "01" "1"
+//	Day of the week: "Mon" "Monday"
+//	Day of the month: "2" "_2" "02"
+//	Day of the year: "__2" "002"
+//	Hour: "15" "3" "03" (PM or AM)
+//	Minute: "4" "04"
+//	Second: "5" "05"
+//	AM/PM mark: "PM"
+//
+// Numeric time zone offsets format as follows:
+//
+//	"-0700"     ±hhmm
+//	"-07:00"    ±hh:mm
+//	"-07"       ±hh
+//	"-070000"   ±hhmmss
+//	"-07:00:00" ±hh:mm:ss
+//
+// Replacing the sign in the format with a Z triggers
+// the ISO 8601 behavior of printing Z instead of an
+// offset for the UTC zone. Thus:
+//
+//	"Z0700"      Z or ±hhmm
+//	"Z07:00"     Z or ±hh:mm
+//	"Z07"        Z or ±hh
+//	"Z070000"    Z or ±hhmmss
+//	"Z07:00:00"  Z or ±hh:mm:ss
+//
+// Within the format string, the underscores in "_2" and "__2" represent spaces
+// that may be replaced by digits if the following number has multiple digits,
+// for compatibility with fixed-width Unix time formats. A leading zero represents
+// a zero-padded value.
+//
+// The formats __2 and 002 are space-padded and zero-padded
+// three-character day of year; there is no unpadded day of year format.
+//
+// A comma or decimal point followed by one or more zeros represents
+// a fractional second, printed to the given number of decimal places.
+// A comma or decimal point followed by one or more nines represents
+// a fractional second, printed to the given number of decimal places, with
+// trailing zeros removed.
+// For example "15:04:05,000" or "15:04:05.000" formats or parses with
+// millisecond precision.
+//
+// Some valid layouts are invalid time values for time.Parse, due to formats
+// such as _ for space padding and Z for zone information.
+const (
+	Layout      = "01/02 03:04:05PM '06 -0700" // The reference time, in numerical order.
+	ANSIC       = "Mon Jan _2 15:04:05 2006"
+	UnixDate    = "Mon Jan _2 15:04:05 MST 2006"
+	RubyDate    = "Mon Jan 02 15:04:05 -0700 2006"
+	RFC822      = "02 Jan 06 15:04 MST"
+	RFC822Z     = "02 Jan 06 15:04 -0700" // RFC822 with numeric zone
+	RFC850      = "Monday, 02-Jan-06 15:04:05 MST"
+	RFC1123     = "Mon, 02 Jan 2006 15:04:05 MST"
+	RFC1123Z    = "Mon, 02 Jan 2006 15:04:05 -0700" // RFC1123 with numeric zone
+	RFC3339     = "2006-01-02T15:04:05Z07:00"
+	RFC3339Nano = "2006-01-02T15:04:05.999999999Z07:00"
+	Kitchen     = "3:04PM"
+	// Handy time stamps.
+	Stamp      = "Jan _2 15:04:05"
+	StampMilli = "Jan _2 15:04:05.000"
+	StampMicro = "Jan _2 15:04:05.000000"
+	StampNano  = "Jan _2 15:04:05.000000000"
+	DateTime   = "2006-01-02 15:04:05"
+	DateOnly   = "2006-01-02"
+	TimeOnly   = "15:04:05"
+)
+
+const (
+	_                        = iota
+	stdLongMonth             = iota + stdNeedDate  // "January"
+	stdMonth                                       // "Jan"
+	stdNumMonth                                    // "1"
+	stdZeroMonth                                   // "01"
+	stdLongWeekDay                                 // "Monday"
+	stdWeekDay                                     // "Mon"
+	stdDay                                         // "2"
+	stdUnderDay                                    // "_2"
+	stdZeroDay                                     // "02"
+	stdUnderYearDay                                // "__2"
+	stdZeroYearDay                                 // "002"
+	stdHour                  = iota + stdNeedClock // "15"
+	stdHour12                                      // "3"
+	stdZeroHour12                                  // "03"
+	stdMinute                                      // "4"
+	stdZeroMinute                                  // "04"
+	stdSecond                                      // "5"
+	stdZeroSecond                                  // "05"
+	stdLongYear              = iota + stdNeedDate  // "2006"
+	stdYear                                        // "06"
+	stdPM                    = iota + stdNeedClock // "PM"
+	stdpm                                          // "pm"
+	stdTZ                    = iota                // "MST"
+	stdISO8601TZ                                   // "Z0700"  // prints Z for UTC
+	stdISO8601SecondsTZ                            // "Z070000"
+	stdISO8601ShortTZ                              // "Z07"
+	stdISO8601ColonTZ                              // "Z07:00" // prints Z for UTC
+	stdISO8601ColonSecondsTZ                       // "Z07:00:00"
+	stdNumTZ                                       // "-0700"  // always numeric
+	stdNumSecondsTz                                // "-070000"
+	stdNumShortTZ                                  // "-07"    // always numeric
+	stdNumColonTZ                                  // "-07:00" // always numeric
+	stdNumColonSecondsTZ                           // "-07:00:00"
+	stdFracSecond0                                 // ".0", ".00", ... , trailing zeros included
+	stdFracSecond9                                 // ".9", ".99", ..., trailing zeros omitted
+
+	stdNeedDate       = 1 << 8             // need month, day, year
+	stdNeedClock      = 2 << 8             // need hour, minute, second
+	stdArgShift       = 16                 // extra argument in high bits, above low stdArgShift
+	stdSeparatorShift = 28                 // extra argument in high 4 bits for fractional second separators
+	stdMask           = 1<<stdArgShift - 1 // mask out argument
+)
+
+// std0x records the std values for "01", "02", ..., "06".
+var std0x = [...]int{stdZeroMonth, stdZeroDay, stdZeroHour12, stdZeroMinute, stdZeroSecond, stdYear}
+
+// startsWithLowerCase reports whether the string has a lower-case letter at the beginning.
+// Its purpose is to prevent matching strings like "Month" when looking for "Mon".
+func startsWithLowerCase(str string) bool {
+	if len(str) == 0 {
+		return false
+	}
+	c := str[0]
+	return 'a' <= c && c <= 'z'
+}
+
+// nextStdChunk finds the first occurrence of a std string in
+// layout and returns the text before, the std string, and the text after.
+func nextStdChunk(layout string) (prefix string, std int, suffix string) {
+	for i := 0; i < len(layout); i++ {
+		switch c := int(layout[i]); c {
+		case 'J': // January, Jan
+			if len(layout) >= i+3 && layout[i:i+3] == "Jan" {
+				if len(layout) >= i+7 && layout[i:i+7] == "January" {
+					return layout[0:i], stdLongMonth, layout[i+7:]
+				}
+				if !startsWithLowerCase(layout[i+3:]) {
+					return layout[0:i], stdMonth, layout[i+3:]
+				}
+			}
+
+		case 'M': // Monday, Mon, MST
+			if len(layout) >= i+3 {
+				if layout[i:i+3] == "Mon" {
+					if len(layout) >= i+6 && layout[i:i+6] == "Monday" {
+						return layout[0:i], stdLongWeekDay, layout[i+6:]
+					}
+					if !startsWithLowerCase(layout[i+3:]) {
+						return layout[0:i], stdWeekDay, layout[i+3:]
+					}
+				}
+				if layout[i:i+3] == "MST" {
+					return layout[0:i], stdTZ, layout[i+3:]
+				}
+			}
+
+		case '0': // 01, 02, 03, 04, 05, 06, 002
+			if len(layout) >= i+2 && '1' <= layout[i+1] && layout[i+1] <= '6' {
+				return layout[0:i], std0x[layout[i+1]-'1'], layout[i+2:]
+			}
+			if len(layout) >= i+3 && layout[i+1] == '0' && layout[i+2] == '2' {
+				return layout[0:i], stdZeroYearDay, layout[i+3:]
+			}
+
+		case '1': // 15, 1
+			if len(layout) >= i+2 && layout[i+1] == '5' {
+				return layout[0:i], stdHour, layout[i+2:]
+			}
+			return layout[0:i], stdNumMonth, layout[i+1:]
+
+		case '2': // 2006, 2
+			if len(layout) >= i+4 && layout[i:i+4] == "2006" {
+				return layout[0:i], stdLongYear, layout[i+4:]
+			}
+			return layout[0:i], stdDay, layout[i+1:]
+
+		case '_': // _2, _2006, __2
+			if len(layout) >= i+2 && layout[i+1] == '2' {
+				//_2006 is really a literal _, followed by stdLongYear
+				if len(layout) >= i+5 && layout[i+1:i+5] == "2006" {
+					return layout[0 : i+1], stdLongYear, layout[i+5:]
+				}
+				return layout[0:i], stdUnderDay, layout[i+2:]
+			}
+			if len(layout) >= i+3 && layout[i+1] == '_' && layout[i+2] == '2' {
+				return layout[0:i], stdUnderYearDay, layout[i+3:]
+			}
+
+		case '3':
+			return layout[0:i], stdHour12, layout[i+1:]
+
+		case '4':
+			return layout[0:i], stdMinute, layout[i+1:]
+
+		case '5':
+			return layout[0:i], stdSecond, layout[i+1:]
+
+		case 'P': // PM
+			if len(layout) >= i+2 && layout[i+1] == 'M' {
+				return layout[0:i], stdPM, layout[i+2:]
+			}
+
+		case 'p': // pm
+			if len(layout) >= i+2 && layout[i+1] == 'm' {
+				return layout[0:i], stdpm, layout[i+2:]
+			}
+
+		case '-': // -070000, -07:00:00, -0700, -07:00, -07
+			if len(layout) >= i+7 && layout[i:i+7] == "-070000" {
+				return layout[0:i], stdNumSecondsTz, layout[i+7:]
+			}
+			if len(layout) >= i+9 && layout[i:i+9] == "-07:00:00" {
+				return layout[0:i], stdNumColonSecondsTZ, layout[i+9:]
+			}
+			if len(layout) >= i+5 && layout[i:i+5] == "-0700" {
+				return layout[0:i], stdNumTZ, layout[i+5:]
+			}
+			if len(layout) >= i+6 && layout[i:i+6] == "-07:00" {
+				return layout[0:i], stdNumColonTZ, layout[i+6:]
+			}
+			if len(layout) >= i+3 && layout[i:i+3] == "-07" {
+				return layout[0:i], stdNumShortTZ, layout[i+3:]
+			}
+
+		case 'Z': // Z070000, Z07:00:00, Z0700, Z07:00,
+			if len(layout) >= i+7 && layout[i:i+7] == "Z070000" {
+				return layout[0:i], stdISO8601SecondsTZ, layout[i+7:]
+			}
+			if len(layout) >= i+9 && layout[i:i+9] == "Z07:00:00" {
+				return layout[0:i], stdISO8601ColonSecondsTZ, layout[i+9:]
+			}
+			if len(layout) >= i+5 && layout[i:i+5] == "Z0700" {
+				return layout[0:i], stdISO8601TZ, layout[i+5:]
+			}
+			if len(layout) >= i+6 && layout[i:i+6] == "Z07:00" {
+				return layout[0:i], stdISO8601ColonTZ, layout[i+6:]
+			}
+			if len(layout) >= i+3 && layout[i:i+3] == "Z07" {
+				return layout[0:i], stdISO8601ShortTZ, layout[i+3:]
+			}
+
+		case '.', ',': // ,000, or .000, or ,999, or .999 - repeated digits for fractional seconds.
+			if i+1 < len(layout) && (layout[i+1] == '0' || layout[i+1] == '9') {
+				ch := layout[i+1]
+				j := i + 1
+				for j < len(layout) && layout[j] == ch {
+					j++
+				}
+				// String of digits must end here - only fractional second is all digits.
+				if !isDigit(layout, j) {
+					code := stdFracSecond0
+					if layout[i+1] == '9' {
+						code = stdFracSecond9
+					}
+					std := stdFracSecond(code, j-(i+1), c)
+					return layout[0:i], std, layout[j:]
+				}
+			}
+		}
+	}
+	return layout, 0, ""
+}
+
+var longDayNames = []string{
+	"Sunday",
+	"Monday",
+	"Tuesday",
+	"Wednesday",
+	"Thursday",
+	"Friday",
+	"Saturday",
+}
+
+var shortDayNames = []string{
+	"Sun",
+	"Mon",
+	"Tue",
+	"Wed",
+	"Thu",
+	"Fri",
+	"Sat",
+}
+
+var shortMonthNames = []string{
+	"Jan",
+	"Feb",
+	"Mar",
+	"Apr",
+	"May",
+	"Jun",
+	"Jul",
+	"Aug",
+	"Sep",
+	"Oct",
+	"Nov",
+	"Dec",
+}
+
+var longMonthNames = []string{
+	"January",
+	"February",
+	"March",
+	"April",
+	"May",
+	"June",
+	"July",
+	"August",
+	"September",
+	"October",
+	"November",
+	"December",
+}
+
+// match reports whether s1 and s2 match ignoring case.
+// It is assumed s1 and s2 are the same length.
+func match(s1, s2 string) bool {
+	for i := 0; i < len(s1); i++ {
+		c1 := s1[i]
+		c2 := s2[i]
+		if c1 != c2 {
+			// Switch to lower-case; 'a'-'A' is known to be a single bit.
+			c1 |= 'a' - 'A'
+			c2 |= 'a' - 'A'
+			if c1 != c2 || c1 < 'a' || c1 > 'z' {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+func lookup(tab []string, val string) (int, string, error) {
+	for i, v := range tab {
+		if len(val) >= len(v) && match(val[0:len(v)], v) {
+			return i, val[len(v):], nil
+		}
+	}
+	return -1, val, errBad
+}
+
+// appendInt appends the decimal form of x to b and returns the result.
+// If the decimal form (excluding sign) is shorter than width, the result is padded with leading 0's.
+// Duplicates functionality in strconv, but avoids dependency.
+func appendInt(b []byte, x int, width int) []byte {
+	u := uint(x)
+	if x < 0 {
+		b = append(b, '-')
+		u = uint(-x)
+	}
+
+	// 2-digit and 4-digit fields are the most common in time formats.
+	utod := func(u uint) byte { return '0' + byte(u) }
+	switch {
+	case width == 2 && u < 1e2:
+		return append(b, utod(u/1e1), utod(u%1e1))
+	case width == 4 && u < 1e4:
+		return append(b, utod(u/1e3), utod(u/1e2%1e1), utod(u/1e1%1e1), utod(u%1e1))
+	}
+
+	// Compute the number of decimal digits.
+	var n int
+	if u == 0 {
+		n = 1
+	}
+	for u2 := u; u2 > 0; u2 /= 10 {
+		n++
+	}
+
+	// Add 0-padding.
+	for pad := width - n; pad > 0; pad-- {
+		b = append(b, '0')
+	}
+
+	// Ensure capacity.
+	if len(b)+n <= cap(b) {
+		b = b[:len(b)+n]
+	} else {
+		b = append(b, make([]byte, n)...)
+	}
+
+	// Assemble decimal in reverse order.
+	i := len(b) - 1
+	for u >= 10 && i > 0 {
+		q := u / 10
+		b[i] = utod(u - q*10)
+		u = q
+		i--
+	}
+	b[i] = utod(u)
+	return b
+}
+
+// Never printed, just needs to be non-nil for return by atoi.
+var errAtoi = errors.New("time: invalid number")
+
+// Duplicates functionality in strconv, but avoids dependency.
+func atoi[bytes []byte | string](s bytes) (x int, err error) {
+	neg := false
+	if len(s) > 0 && (s[0] == '-' || s[0] == '+') {
+		neg = s[0] == '-'
+		s = s[1:]
+	}
+	q, rem, err := leadingInt(s)
+	x = int(q)
+	if err != nil || len(rem) > 0 {
+		return 0, errAtoi
+	}
+	if neg {
+		x = -x
+	}
+	return x, nil
+}
+
+// The "std" value passed to appendNano contains two packed fields: the number of
+// digits after the decimal and the separator character (period or comma).
+// These functions pack and unpack that variable.
+func stdFracSecond(code, n, c int) int {
+	// Use 0xfff to make the failure case even more absurd.
+	if c == '.' {
+		return code | ((n & 0xfff) << stdArgShift)
+	}
+	return code | ((n & 0xfff) << stdArgShift) | 1<<stdSeparatorShift
+}
+
+func digitsLen(std int) int {
+	return (std >> stdArgShift) & 0xfff
+}
+
+func separator(std int) byte {
+	if (std >> stdSeparatorShift) == 0 {
+		return '.'
+	}
+	return ','
+}
+
+// appendNano appends a fractional second, as nanoseconds, to b
+// and returns the result. The nanosec must be within [0, 999999999].
+func appendNano(b []byte, nanosec int, std int) []byte {
+	trim := std&stdMask == stdFracSecond9
+	n := digitsLen(std)
+	if trim && (n == 0 || nanosec == 0) {
+		return b
+	}
+	dot := separator(std)
+	b = append(b, dot)
+	b = appendInt(b, nanosec, 9)
+	if n < 9 {
+		b = b[:len(b)-9+n]
+	}
+	if trim {
+		for len(b) > 0 && b[len(b)-1] == '0' {
+			b = b[:len(b)-1]
+		}
+		if len(b) > 0 && b[len(b)-1] == dot {
+			b = b[:len(b)-1]
+		}
+	}
+	return b
+}
+
+// String returns the time formatted using the format string
+//
+//	"2006-01-02 15:04:05.999999999 -0700 MST"
+//
+// If the time has a monotonic clock reading, the returned string
+// includes a final field "m=±<value>", where value is the monotonic
+// clock reading formatted as a decimal number of seconds.
+//
+// The returned string is meant for debugging; for a stable serialized
+// representation, use t.MarshalText, t.MarshalBinary, or t.Format
+// with an explicit format string.
+func (t Time) String() string {
+	s := t.Format("2006-01-02 15:04:05.999999999 -0700 MST")
+
+	// Format monotonic clock reading as m=±ddd.nnnnnnnnn.
+	if t.wall&hasMonotonic != 0 {
+		m2 := uint64(t.ext)
+		sign := byte('+')
+		if t.ext < 0 {
+			sign = '-'
+			m2 = -m2
+		}
+		m1, m2 := m2/1e9, m2%1e9
+		m0, m1 := m1/1e9, m1%1e9
+		buf := make([]byte, 0, 24)
+		buf = append(buf, " m="...)
+		buf = append(buf, sign)
+		wid := 0
+		if m0 != 0 {
+			buf = appendInt(buf, int(m0), 0)
+			wid = 9
+		}
+		buf = appendInt(buf, int(m1), wid)
+		buf = append(buf, '.')
+		buf = appendInt(buf, int(m2), 9)
+		s += string(buf)
+	}
+	return s
+}
+
+// GoString implements fmt.GoStringer and formats t to be printed in Go source
+// code.
+func (t Time) GoString() string {
+	abs := t.abs()
+	year, month, day, _ := absDate(abs, true)
+	hour, minute, second := absClock(abs)
+
+	buf := make([]byte, 0, len("time.Date(9999, time.September, 31, 23, 59, 59, 999999999, time.Local)"))
+	buf = append(buf, "time.Date("...)
+	buf = appendInt(buf, year, 0)
+	if January <= month && month <= December {
+		buf = append(buf, ", time."...)
+		buf = append(buf, longMonthNames[month-1]...)
+	} else {
+		// It's difficult to construct a time.Time with a date outside the
+		// standard range but we might as well try to handle the case.
+		buf = appendInt(buf, int(month), 0)
+	}
+	buf = append(buf, ", "...)
+	buf = appendInt(buf, day, 0)
+	buf = append(buf, ", "...)
+	buf = appendInt(buf, hour, 0)
+	buf = append(buf, ", "...)
+	buf = appendInt(buf, minute, 0)
+	buf = append(buf, ", "...)
+	buf = appendInt(buf, second, 0)
+	buf = append(buf, ", "...)
+	buf = appendInt(buf, t.Nanosecond(), 0)
+	buf = append(buf, ", "...)
+	switch loc := t.Location(); loc {
+	case UTC, nil:
+		buf = append(buf, "time.UTC"...)
+	case Local:
+		buf = append(buf, "time.Local"...)
+	default:
+		// there are several options for how we could display this, none of
+		// which are great:
+		//
+		// - use Location(loc.name), which is not technically valid syntax
+		// - use LoadLocation(loc.name), which will cause a syntax error when
+		// embedded and also would require us to escape the string without
+		// importing fmt or strconv
+		// - try to use FixedZone, which would also require escaping the name
+		// and would represent e.g. "America/Los_Angeles" daylight saving time
+		// shifts inaccurately
+		// - use the pointer format, which is no worse than you'd get with the
+		// old fmt.Sprintf("%#v", t) format.
+		//
+		// Of these, Location(loc.name) is the least disruptive. This is an edge
+		// case we hope not to hit too often.
+		buf = append(buf, `time.Location(`...)
+		buf = append(buf, quote(loc.name)...)
+		buf = append(buf, ')')
+	}
+	buf = append(buf, ')')
+	return string(buf)
+}
+
+// Format returns a textual representation of the time value formatted according
+// to the layout defined by the argument. See the documentation for the
+// constant called Layout to see how to represent the layout format.
+//
+// The executable example for Time.Format demonstrates the working
+// of the layout string in detail and is a good reference.
+func (t Time) Format(layout string) string {
+	const bufSize = 64
+	var b []byte
+	max := len(layout) + 10
+	if max < bufSize {
+		var buf [bufSize]byte
+		b = buf[:0]
+	} else {
+		b = make([]byte, 0, max)
+	}
+	b = t.AppendFormat(b, layout)
+	return string(b)
+}
+
+// AppendFormat is like Format but appends the textual
+// representation to b and returns the extended buffer.
+func (t Time) AppendFormat(b []byte, layout string) []byte {
+	// Optimize for RFC3339 as it accounts for over half of all representations.
+	switch layout {
+	case RFC3339:
+		return t.appendFormatRFC3339(b, false)
+	case RFC3339Nano:
+		return t.appendFormatRFC3339(b, true)
+	default:
+		return t.appendFormat(b, layout)
+	}
+}
+
+func (t Time) appendFormat(b []byte, layout string) []byte {
+	var (
+		name, offset, abs = t.locabs()
+
+		year  int = -1
+		month Month
+		day   int
+		yday  int
+		hour  int = -1
+		min   int
+		sec   int
+	)
+
+	// Each iteration generates one std value.
+	for layout != "" {
+		prefix, std, suffix := nextStdChunk(layout)
+		if prefix != "" {
+			b = append(b, prefix...)
+		}
+		if std == 0 {
+			break
+		}
+		layout = suffix
+
+		// Compute year, month, day if needed.
+		if year < 0 && std&stdNeedDate != 0 {
+			year, month, day, yday = absDate(abs, true)
+			yday++
+		}
+
+		// Compute hour, minute, second if needed.
+		if hour < 0 && std&stdNeedClock != 0 {
+			hour, min, sec = absClock(abs)
+		}
+
+		switch std & stdMask {
+		case stdYear:
+			y := year
+			if y < 0 {
+				y = -y
+			}
+			b = appendInt(b, y%100, 2)
+		case stdLongYear:
+			b = appendInt(b, year, 4)
+		case stdMonth:
+			b = append(b, month.String()[:3]...)
+		case stdLongMonth:
+			m := month.String()
+			b = append(b, m...)
+		case stdNumMonth:
+			b = appendInt(b, int(month), 0)
+		case stdZeroMonth:
+			b = appendInt(b, int(month), 2)
+		case stdWeekDay:
+			b = append(b, absWeekday(abs).String()[:3]...)
+		case stdLongWeekDay:
+			s := absWeekday(abs).String()
+			b = append(b, s...)
+		case stdDay:
+			b = appendInt(b, day, 0)
+		case stdUnderDay:
+			if day < 10 {
+				b = append(b, ' ')
+			}
+			b = appendInt(b, day, 0)
+		case stdZeroDay:
+			b = appendInt(b, day, 2)
+		case stdUnderYearDay:
+			if yday < 100 {
+				b = append(b, ' ')
+				if yday < 10 {
+					b = append(b, ' ')
+				}
+			}
+			b = appendInt(b, yday, 0)
+		case stdZeroYearDay:
+			b = appendInt(b, yday, 3)
+		case stdHour:
+			b = appendInt(b, hour, 2)
+		case stdHour12:
+			// Noon is 12PM, midnight is 12AM.
+			hr := hour % 12
+			if hr == 0 {
+				hr = 12
+			}
+			b = appendInt(b, hr, 0)
+		case stdZeroHour12:
+			// Noon is 12PM, midnight is 12AM.
+			hr := hour % 12
+			if hr == 0 {
+				hr = 12
+			}
+			b = appendInt(b, hr, 2)
+		case stdMinute:
+			b = appendInt(b, min, 0)
+		case stdZeroMinute:
+			b = appendInt(b, min, 2)
+		case stdSecond:
+			b = appendInt(b, sec, 0)
+		case stdZeroSecond:
+			b = appendInt(b, sec, 2)
+		case stdPM:
+			if hour >= 12 {
+				b = append(b, "PM"...)
+			} else {
+				b = append(b, "AM"...)
+			}
+		case stdpm:
+			if hour >= 12 {
+				b = append(b, "pm"...)
+			} else {
+				b = append(b, "am"...)
+			}
+		case stdISO8601TZ, stdISO8601ColonTZ, stdISO8601SecondsTZ, stdISO8601ShortTZ, stdISO8601ColonSecondsTZ, stdNumTZ, stdNumColonTZ, stdNumSecondsTz, stdNumShortTZ, stdNumColonSecondsTZ:
+			// Ugly special case. We cheat and take the "Z" variants
+			// to mean "the time zone as formatted for ISO 8601".
+			if offset == 0 && (std == stdISO8601TZ || std == stdISO8601ColonTZ || std == stdISO8601SecondsTZ || std == stdISO8601ShortTZ || std == stdISO8601ColonSecondsTZ) {
+				b = append(b, 'Z')
+				break
+			}
+			zone := offset / 60 // convert to minutes
+			absoffset := offset
+			if zone < 0 {
+				b = append(b, '-')
+				zone = -zone
+				absoffset = -absoffset
+			} else {
+				b = append(b, '+')
+			}
+			b = appendInt(b, zone/60, 2)
+			if std == stdISO8601ColonTZ || std == stdNumColonTZ || std == stdISO8601ColonSecondsTZ || std == stdNumColonSecondsTZ {
+				b = append(b, ':')
+			}
+			if std != stdNumShortTZ && std != stdISO8601ShortTZ {
+				b = appendInt(b, zone%60, 2)
+			}
+
+			// append seconds if appropriate
+			if std == stdISO8601SecondsTZ || std == stdNumSecondsTz || std == stdNumColonSecondsTZ || std == stdISO8601ColonSecondsTZ {
+				if std == stdNumColonSecondsTZ || std == stdISO8601ColonSecondsTZ {
+					b = append(b, ':')
+				}
+				b = appendInt(b, absoffset%60, 2)
+			}
+
+		case stdTZ:
+			if name != "" {
+				b = append(b, name...)
+				break
+			}
+			// No time zone known for this time, but we must print one.
+			// Use the -0700 format.
+			zone := offset / 60 // convert to minutes
+			if zone < 0 {
+				b = append(b, '-')
+				zone = -zone
+			} else {
+				b = append(b, '+')
+			}
+			b = appendInt(b, zone/60, 2)
+			b = appendInt(b, zone%60, 2)
+		case stdFracSecond0, stdFracSecond9:
+			b = appendNano(b, t.Nanosecond(), std)
+		}
+	}
+	return b
+}
+
+var errBad = errors.New("bad value for field") // placeholder not passed to user
+
+// ParseError describes a problem parsing a time string.
+type ParseError struct {
+	Layout     string
+	Value      string
+	LayoutElem string
+	ValueElem  string
+	Message    string
+}
+
+// newParseError creates a new ParseError.
+// The provided value and valueElem are cloned to avoid escaping their values.
+func newParseError(layout, value, layoutElem, valueElem, message string) *ParseError {
+	valueCopy := cloneString(value)
+	valueElemCopy := cloneString(valueElem)
+	return &ParseError{layout, valueCopy, layoutElem, valueElemCopy, message}
+}
+
+// cloneString returns a string copy of s.
+// Do not use strings.Clone to avoid dependency on strings package.
+func cloneString(s string) string {
+	return string([]byte(s))
+}
+
+// These are borrowed from unicode/utf8 and strconv and replicate behavior in
+// that package, since we can't take a dependency on either.
+const (
+	lowerhex  = "0123456789abcdef"
+	runeSelf  = 0x80
+	runeError = '\uFFFD'
+)
+
+func quote(s string) string {
+	buf := make([]byte, 1, len(s)+2) // slice will be at least len(s) + quotes
+	buf[0] = '"'
+	for i, c := range s {
+		if c >= runeSelf || c < ' ' {
+			// This means you are asking us to parse a time.Duration or
+			// time.Location with unprintable or non-ASCII characters in it.
+			// We don't expect to hit this case very often. We could try to
+			// reproduce strconv.Quote's behavior with full fidelity but
+			// given how rarely we expect to hit these edge cases, speed and
+			// conciseness are better.
+			var width int
+			if c == runeError {
+				width = 1
+				if i+2 < len(s) && s[i:i+3] == string(runeError) {
+					width = 3
+				}
+			} else {
+				width = len(string(c))
+			}
+			for j := 0; j < width; j++ {
+				buf = append(buf, `\x`...)
+				buf = append(buf, lowerhex[s[i+j]>>4])
+				buf = append(buf, lowerhex[s[i+j]&0xF])
+			}
+		} else {
+			if c == '"' || c == '\\' {
+				buf = append(buf, '\\')
+			}
+			buf = append(buf, string(c)...)
+		}
+	}
+	buf = append(buf, '"')
+	return string(buf)
+}
+
+// Error returns the string representation of a ParseError.
+func (e *ParseError) Error() string {
+	if e.Message == "" {
+		return "parsing time " +
+			quote(e.Value) + " as " +
+			quote(e.Layout) + ": cannot parse " +
+			quote(e.ValueElem) + " as " +
+			quote(e.LayoutElem)
+	}
+	return "parsing time " +
+		quote(e.Value) + e.Message
+}
+
+// isDigit reports whether s[i] is in range and is a decimal digit.
+func isDigit[bytes []byte | string](s bytes, i int) bool {
+	if len(s) <= i {
+		return false
+	}
+	c := s[i]
+	return '0' <= c && c <= '9'
+}
+
+// getnum parses s[0:1] or s[0:2] (fixed forces s[0:2])
+// as a decimal integer and returns the integer and the
+// remainder of the string.
+func getnum(s string, fixed bool) (int, string, error) {
+	if !isDigit(s, 0) {
+		return 0, s, errBad
+	}
+	if !isDigit(s, 1) {
+		if fixed {
+			return 0, s, errBad
+		}
+		return int(s[0] - '0'), s[1:], nil
+	}
+	return int(s[0]-'0')*10 + int(s[1]-'0'), s[2:], nil
+}
+
+// getnum3 parses s[0:1], s[0:2], or s[0:3] (fixed forces s[0:3])
+// as a decimal integer and returns the integer and the remainder
+// of the string.
+func getnum3(s string, fixed bool) (int, string, error) {
+	var n, i int
+	for i = 0; i < 3 && isDigit(s, i); i++ {
+		n = n*10 + int(s[i]-'0')
+	}
+	if i == 0 || fixed && i != 3 {
+		return 0, s, errBad
+	}
+	return n, s[i:], nil
+}
+
+func cutspace(s string) string {
+	for len(s) > 0 && s[0] == ' ' {
+		s = s[1:]
+	}
+	return s
+}
+
+// skip removes the given prefix from value,
+// treating runs of space characters as equivalent.
+func skip(value, prefix string) (string, error) {
+	for len(prefix) > 0 {
+		if prefix[0] == ' ' {
+			if len(value) > 0 && value[0] != ' ' {
+				return value, errBad
+			}
+			prefix = cutspace(prefix)
+			value = cutspace(value)
+			continue
+		}
+		if len(value) == 0 || value[0] != prefix[0] {
+			return value, errBad
+		}
+		prefix = prefix[1:]
+		value = value[1:]
+	}
+	return value, nil
+}
+
+// Parse parses a formatted string and returns the time value it represents.
+// See the documentation for the constant called Layout to see how to
+// represent the format. The second argument must be parseable using
+// the format string (layout) provided as the first argument.
+//
+// The example for Time.Format demonstrates the working of the layout string
+// in detail and is a good reference.
+//
+// When parsing (only), the input may contain a fractional second
+// field immediately after the seconds field, even if the layout does not
+// signify its presence. In that case either a comma or a decimal point
+// followed by a maximal series of digits is parsed as a fractional second.
+// Fractional seconds are truncated to nanosecond precision.
+//
+// Elements omitted from the layout are assumed to be zero or, when
+// zero is impossible, one, so parsing "3:04pm" returns the time
+// corresponding to Jan 1, year 0, 15:04:00 UTC (note that because the year is
+// 0, this time is before the zero Time).
+// Years must be in the range 0000..9999. The day of the week is checked
+// for syntax but it is otherwise ignored.
+//
+// For layouts specifying the two-digit year 06, a value NN >= 69 will be treated
+// as 19NN and a value NN < 69 will be treated as 20NN.
+//
+// The remainder of this comment describes the handling of time zones.
+//
+// In the absence of a time zone indicator, Parse returns a time in UTC.
+//
+// When parsing a time with a zone offset like -0700, if the offset corresponds
+// to a time zone used by the current location (Local), then Parse uses that
+// location and zone in the returned time. Otherwise it records the time as
+// being in a fabricated location with time fixed at the given zone offset.
+//
+// When parsing a time with a zone abbreviation like MST, if the zone abbreviation
+// has a defined offset in the current location, then that offset is used.
+// The zone abbreviation "UTC" is recognized as UTC regardless of location.
+// If the zone abbreviation is unknown, Parse records the time as being
+// in a fabricated location with the given zone abbreviation and a zero offset.
+// This choice means that such a time can be parsed and reformatted with the
+// same layout losslessly, but the exact instant used in the representation will
+// differ by the actual zone offset. To avoid such problems, prefer time layouts
+// that use a numeric zone offset, or use ParseInLocation.
+func Parse(layout, value string) (Time, error) {
+	// Optimize for RFC3339 as it accounts for over half of all representations.
+	if layout == RFC3339 || layout == RFC3339Nano {
+		if t, ok := parseRFC3339(value, Local); ok {
+			return t, nil
+		}
+	}
+	return parse(layout, value, UTC, Local)
+}
+
+// ParseInLocation is like Parse but differs in two important ways.
+// First, in the absence of time zone information, Parse interprets a time as UTC;
+// ParseInLocation interprets the time as in the given location.
+// Second, when given a zone offset or abbreviation, Parse tries to match it
+// against the Local location; ParseInLocation uses the given location.
+func ParseInLocation(layout, value string, loc *Location) (Time, error) {
+	// Optimize for RFC3339 as it accounts for over half of all representations.
+	if layout == RFC3339 || layout == RFC3339Nano {
+		if t, ok := parseRFC3339(value, loc); ok {
+			return t, nil
+		}
+	}
+	return parse(layout, value, loc, loc)
+}
+
+func parse(layout, value string, defaultLocation, local *Location) (Time, error) {
+	alayout, avalue := layout, value
+	rangeErrString := "" // set if a value is out of range
+	amSet := false       // do we need to subtract 12 from the hour for midnight?
+	pmSet := false       // do we need to add 12 to the hour?
+
+	// Time being constructed.
+	var (
+		year       int
+		month      int = -1
+		day        int = -1
+		yday       int = -1
+		hour       int
+		min        int
+		sec        int
+		nsec       int
+		z          *Location
+		zoneOffset int = -1
+		zoneName   string
+	)
+
+	// Each iteration processes one std value.
+	for {
+		var err error
+		prefix, std, suffix := nextStdChunk(layout)
+		stdstr := layout[len(prefix) : len(layout)-len(suffix)]
+		value, err = skip(value, prefix)
+		if err != nil {
+			return Time{}, newParseError(alayout, avalue, prefix, value, "")
+		}
+		if std == 0 {
+			if len(value) != 0 {
+				return Time{}, newParseError(alayout, avalue, "", value, ": extra text: "+quote(value))
+			}
+			break
+		}
+		layout = suffix
+		var p string
+		hold := value
+		switch std & stdMask {
+		case stdYear:
+			if len(value) < 2 {
+				err = errBad
+				break
+			}
+			p, value = value[0:2], value[2:]
+			year, err = atoi(p)
+			if err != nil {
+				break
+			}
+			if year >= 69 { // Unix time starts Dec 31 1969 in some time zones
+				year += 1900
+			} else {
+				year += 2000
+			}
+		case stdLongYear:
+			if len(value) < 4 || !isDigit(value, 0) {
+				err = errBad
+				break
+			}
+			p, value = value[0:4], value[4:]
+			year, err = atoi(p)
+		case stdMonth:
+			month, value, err = lookup(shortMonthNames, value)
+			month++
+		case stdLongMonth:
+			month, value, err = lookup(longMonthNames, value)
+			month++
+		case stdNumMonth, stdZeroMonth:
+			month, value, err = getnum(value, std == stdZeroMonth)
+			if err == nil && (month <= 0 || 12 < month) {
+				rangeErrString = "month"
+			}
+		case stdWeekDay:
+			// Ignore weekday except for error checking.
+			_, value, err = lookup(shortDayNames, value)
+		case stdLongWeekDay:
+			_, value, err = lookup(longDayNames, value)
+		case stdDay, stdUnderDay, stdZeroDay:
+			if std == stdUnderDay && len(value) > 0 && value[0] == ' ' {
+				value = value[1:]
+			}
+			day, value, err = getnum(value, std == stdZeroDay)
+			// Note that we allow any one- or two-digit day here.
+			// The month, day, year combination is validated after we've completed parsing.
+		case stdUnderYearDay, stdZeroYearDay:
+			for i := 0; i < 2; i++ {
+				if std == stdUnderYearDay && len(value) > 0 && value[0] == ' ' {
+					value = value[1:]
+				}
+			}
+			yday, value, err = getnum3(value, std == stdZeroYearDay)
+			// Note that we allow any one-, two-, or three-digit year-day here.
+			// The year-day, year combination is validated after we've completed parsing.
+		case stdHour:
+			hour, value, err = getnum(value, false)
+			if hour < 0 || 24 <= hour {
+				rangeErrString = "hour"
+			}
+		case stdHour12, stdZeroHour12:
+			hour, value, err = getnum(value, std == stdZeroHour12)
+			if hour < 0 || 12 < hour {
+				rangeErrString = "hour"
+			}
+		case stdMinute, stdZeroMinute:
+			min, value, err = getnum(value, std == stdZeroMinute)
+			if min < 0 || 60 <= min {
+				rangeErrString = "minute"
+			}
+		case stdSecond, stdZeroSecond:
+			sec, value, err = getnum(value, std == stdZeroSecond)
+			if err != nil {
+				break
+			}
+			if sec < 0 || 60 <= sec {
+				rangeErrString = "second"
+				break
+			}
+			// Special case: do we have a fractional second but no
+			// fractional second in the format?
+			if len(value) >= 2 && commaOrPeriod(value[0]) && isDigit(value, 1) {
+				_, std, _ = nextStdChunk(layout)
+				std &= stdMask
+				if std == stdFracSecond0 || std == stdFracSecond9 {
+					// Fractional second in the layout; proceed normally
+					break
+				}
+				// No fractional second in the layout but we have one in the input.
+				n := 2
+				for ; n < len(value) && isDigit(value, n); n++ {
+				}
+				nsec, rangeErrString, err = parseNanoseconds(value, n)
+				value = value[n:]
+			}
+		case stdPM:
+			if len(value) < 2 {
+				err = errBad
+				break
+			}
+			p, value = value[0:2], value[2:]
+			switch p {
+			case "PM":
+				pmSet = true
+			case "AM":
+				amSet = true
+			default:
+				err = errBad
+			}
+		case stdpm:
+			if len(value) < 2 {
+				err = errBad
+				break
+			}
+			p, value = value[0:2], value[2:]
+			switch p {
+			case "pm":
+				pmSet = true
+			case "am":
+				amSet = true
+			default:
+				err = errBad
+			}
+		case stdISO8601TZ, stdISO8601ColonTZ, stdISO8601SecondsTZ, stdISO8601ShortTZ, stdISO8601ColonSecondsTZ, stdNumTZ, stdNumShortTZ, stdNumColonTZ, stdNumSecondsTz, stdNumColonSecondsTZ:
+			if (std == stdISO8601TZ || std == stdISO8601ShortTZ || std == stdISO8601ColonTZ) && len(value) >= 1 && value[0] == 'Z' {
+				value = value[1:]
+				z = UTC
+				break
+			}
+			var sign, hour, min, seconds string
+			if std == stdISO8601ColonTZ || std == stdNumColonTZ {
+				if len(value) < 6 {
+					err = errBad
+					break
+				}
+				if value[3] != ':' {
+					err = errBad
+					break
+				}
+				sign, hour, min, seconds, value = value[0:1], value[1:3], value[4:6], "00", value[6:]
+			} else if std == stdNumShortTZ || std == stdISO8601ShortTZ {
+				if len(value) < 3 {
+					err = errBad
+					break
+				}
+				sign, hour, min, seconds, value = value[0:1], value[1:3], "00", "00", value[3:]
+			} else if std == stdISO8601ColonSecondsTZ || std == stdNumColonSecondsTZ {
+				if len(value) < 9 {
+					err = errBad
+					break
+				}
+				if value[3] != ':' || value[6] != ':' {
+					err = errBad
+					break
+				}
+				sign, hour, min, seconds, value = value[0:1], value[1:3], value[4:6], value[7:9], value[9:]
+			} else if std == stdISO8601SecondsTZ || std == stdNumSecondsTz {
+				if len(value) < 7 {
+					err = errBad
+					break
+				}
+				sign, hour, min, seconds, value = value[0:1], value[1:3], value[3:5], value[5:7], value[7:]
+			} else {
+				if len(value) < 5 {
+					err = errBad
+					break
+				}
+				sign, hour, min, seconds, value = value[0:1], value[1:3], value[3:5], "00", value[5:]
+			}
+			var hr, mm, ss int
+			hr, _, err = getnum(hour, true)
+			if err == nil {
+				mm, _, err = getnum(min, true)
+			}
+			if err == nil {
+				ss, _, err = getnum(seconds, true)
+			}
+			zoneOffset = (hr*60+mm)*60 + ss // offset is in seconds
+			switch sign[0] {
+			case '+':
+			case '-':
+				zoneOffset = -zoneOffset
+			default:
+				err = errBad
+			}
+		case stdTZ:
+			// Does it look like a time zone?
+			if len(value) >= 3 && value[0:3] == "UTC" {
+				z = UTC
+				value = value[3:]
+				break
+			}
+			n, ok := parseTimeZone(value)
+			if !ok {
+				err = errBad
+				break
+			}
+			zoneName, value = value[:n], value[n:]
+
+		case stdFracSecond0:
+			// stdFracSecond0 requires the exact number of digits as specified in
+			// the layout.
+			ndigit := 1 + digitsLen(std)
+			if len(value) < ndigit {
+				err = errBad
+				break
+			}
+			nsec, rangeErrString, err = parseNanoseconds(value, ndigit)
+			value = value[ndigit:]
+
+		case stdFracSecond9:
+			if len(value) < 2 || !commaOrPeriod(value[0]) || value[1] < '0' || '9' < value[1] {
+				// Fractional second omitted.
+				break
+			}
+			// Take any number of digits, even more than asked for,
+			// because it is what the stdSecond case would do.
+			i := 0
+			for i+1 < len(value) && '0' <= value[i+1] && value[i+1] <= '9' {
+				i++
+			}
+			nsec, rangeErrString, err = parseNanoseconds(value, 1+i)
+			value = value[1+i:]
+		}
+		if rangeErrString != "" {
+			return Time{}, newParseError(alayout, avalue, stdstr, value, ": "+rangeErrString+" out of range")
+		}
+		if err != nil {
+			return Time{}, newParseError(alayout, avalue, stdstr, hold, "")
+		}
+	}
+	if pmSet && hour < 12 {
+		hour += 12
+	} else if amSet && hour == 12 {
+		hour = 0
+	}
+
+	// Convert yday to day, month.
+	if yday >= 0 {
+		var d int
+		var m int
+		if isLeap(year) {
+			if yday == 31+29 {
+				m = int(February)
+				d = 29
+			} else if yday > 31+29 {
+				yday--
+			}
+		}
+		if yday < 1 || yday > 365 {
+			return Time{}, newParseError(alayout, avalue, "", value, ": day-of-year out of range")
+		}
+		if m == 0 {
+			m = (yday-1)/31 + 1
+			if int(daysBefore[m]) < yday {
+				m++
+			}
+			d = yday - int(daysBefore[m-1])
+		}
+		// If month, day already seen, yday's m, d must match.
+		// Otherwise, set them from m, d.
+		if month >= 0 && month != m {
+			return Time{}, newParseError(alayout, avalue, "", value, ": day-of-year does not match month")
+		}
+		month = m
+		if day >= 0 && day != d {
+			return Time{}, newParseError(alayout, avalue, "", value, ": day-of-year does not match day")
+		}
+		day = d
+	} else {
+		if month < 0 {
+			month = int(January)
+		}
+		if day < 0 {
+			day = 1
+		}
+	}
+
+	// Validate the day of the month.
+	if day < 1 || day > daysIn(Month(month), year) {
+		return Time{}, newParseError(alayout, avalue, "", value, ": day out of range")
+	}
+
+	if z != nil {
+		return Date(year, Month(month), day, hour, min, sec, nsec, z), nil
+	}
+
+	if zoneOffset != -1 {
+		t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
+		t.addSec(-int64(zoneOffset))
+
+		// Look for local zone with the given offset.
+		// If that zone was in effect at the given time, use it.
+		name, offset, _, _, _ := local.lookup(t.unixSec())
+		if offset == zoneOffset && (zoneName == "" || name == zoneName) {
+			t.setLoc(local)
+			return t, nil
+		}
+
+		// Otherwise create fake zone to record offset.
+		zoneNameCopy := cloneString(zoneName) // avoid leaking the input value
+		t.setLoc(FixedZone(zoneNameCopy, zoneOffset))
+		return t, nil
+	}
+
+	if zoneName != "" {
+		t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
+		// Look for local zone with the given offset.
+		// If that zone was in effect at the given time, use it.
+		offset, ok := local.lookupName(zoneName, t.unixSec())
+		if ok {
+			t.addSec(-int64(offset))
+			t.setLoc(local)
+			return t, nil
+		}
+
+		// Otherwise, create fake zone with unknown offset.
+		if len(zoneName) > 3 && zoneName[:3] == "GMT" {
+			offset, _ = atoi(zoneName[3:]) // Guaranteed OK by parseGMT.
+			offset *= 3600
+		}
+		zoneNameCopy := cloneString(zoneName) // avoid leaking the input value
+		t.setLoc(FixedZone(zoneNameCopy, offset))
+		return t, nil
+	}
+
+	// Otherwise, fall back to default.
+	return Date(year, Month(month), day, hour, min, sec, nsec, defaultLocation), nil
+}
+
+// parseTimeZone parses a time zone string and returns its length. Time zones
+// are human-generated and unpredictable. We can't do precise error checking.
+// On the other hand, for a correct parse there must be a time zone at the
+// beginning of the string, so it's almost always true that there's one
+// there. We look at the beginning of the string for a run of upper-case letters.
+// If there are more than 5, it's an error.
+// If there are 4 or 5 and the last is a T, it's a time zone.
+// If there are 3, it's a time zone.
+// Otherwise, other than special cases, it's not a time zone.
+// GMT is special because it can have an hour offset.
+func parseTimeZone(value string) (length int, ok bool) {
+	if len(value) < 3 {
+		return 0, false
+	}
+	// Special case 1: ChST and MeST are the only zones with a lower-case letter.
+	if len(value) >= 4 && (value[:4] == "ChST" || value[:4] == "MeST") {
+		return 4, true
+	}
+	// Special case 2: GMT may have an hour offset; treat it specially.
+	if value[:3] == "GMT" {
+		length = parseGMT(value)
+		return length, true
+	}
+	// Special Case 3: Some time zones are not named, but have +/-00 format
+	if value[0] == '+' || value[0] == '-' {
+		length = parseSignedOffset(value)
+		ok := length > 0 // parseSignedOffset returns 0 in case of bad input
+		return length, ok
+	}
+	// How many upper-case letters are there? Need at least three, at most five.
+	var nUpper int
+	for nUpper = 0; nUpper < 6; nUpper++ {
+		if nUpper >= len(value) {
+			break
+		}
+		if c := value[nUpper]; c < 'A' || 'Z' < c {
+			break
+		}
+	}
+	switch nUpper {
+	case 0, 1, 2, 6:
+		return 0, false
+	case 5: // Must end in T to match.
+		if value[4] == 'T' {
+			return 5, true
+		}
+	case 4:
+		// Must end in T, except one special case.
+		if value[3] == 'T' || value[:4] == "WITA" {
+			return 4, true
+		}
+	case 3:
+		return 3, true
+	}
+	return 0, false
+}
+
+// parseGMT parses a GMT time zone. The input string is known to start "GMT".
+// The function checks whether that is followed by a sign and a number in the
+// range -23 through +23 excluding zero.
+func parseGMT(value string) int {
+	value = value[3:]
+	if len(value) == 0 {
+		return 3
+	}
+
+	return 3 + parseSignedOffset(value)
+}
+
+// parseSignedOffset parses a signed timezone offset (e.g. "+03" or "-04").
+// The function checks for a signed number in the range -23 through +23 excluding zero.
+// Returns length of the found offset string or 0 otherwise.
+func parseSignedOffset(value string) int {
+	sign := value[0]
+	if sign != '-' && sign != '+' {
+		return 0
+	}
+	x, rem, err := leadingInt(value[1:])
+
+	// fail if nothing consumed by leadingInt
+	if err != nil || value[1:] == rem {
+		return 0
+	}
+	if x > 23 {
+		return 0
+	}
+	return len(value) - len(rem)
+}
+
+func commaOrPeriod(b byte) bool {
+	return b == '.' || b == ','
+}
+
+func parseNanoseconds[bytes []byte | string](value bytes, nbytes int) (ns int, rangeErrString string, err error) {
+	if !commaOrPeriod(value[0]) {
+		err = errBad
+		return
+	}
+	if nbytes > 10 {
+		value = value[:10]
+		nbytes = 10
+	}
+	if ns, err = atoi(value[1:nbytes]); err != nil {
+		return
+	}
+	if ns < 0 {
+		rangeErrString = "fractional second"
+		return
+	}
+	// We need nanoseconds, which means scaling by the number
+	// of missing digits in the format, maximum length 10.
+	scaleDigits := 10 - nbytes
+	for i := 0; i < scaleDigits; i++ {
+		ns *= 10
+	}
+	return
+}
+
+var errLeadingInt = errors.New("time: bad [0-9]*") // never printed
+
+// leadingInt consumes the leading [0-9]* from s.
+func leadingInt[bytes []byte | string](s bytes) (x uint64, rem bytes, err error) {
+	i := 0
+	for ; i < len(s); i++ {
+		c := s[i]
+		if c < '0' || c > '9' {
+			break
+		}
+		if x > 1<<63/10 {
+			// overflow
+			return 0, rem, errLeadingInt
+		}
+		x = x*10 + uint64(c) - '0'
+		if x > 1<<63 {
+			// overflow
+			return 0, rem, errLeadingInt
+		}
+	}
+	return x, s[i:], nil
+}
+
+// leadingFraction consumes the leading [0-9]* from s.
+// It is used only for fractions, so does not return an error on overflow,
+// it just stops accumulating precision.
+func leadingFraction(s string) (x uint64, scale float64, rem string) {
+	i := 0
+	scale = 1
+	overflow := false
+	for ; i < len(s); i++ {
+		c := s[i]
+		if c < '0' || c > '9' {
+			break
+		}
+		if overflow {
+			continue
+		}
+		if x > (1<<63-1)/10 {
+			// It's possible for overflow to give a positive number, so take care.
+			overflow = true
+			continue
+		}
+		y := x*10 + uint64(c) - '0'
+		if y > 1<<63 {
+			overflow = true
+			continue
+		}
+		x = y
+		scale *= 10
+	}
+	return x, scale, s[i:]
+}
+
+var unitMap = map[string]uint64{
+	"ns": uint64(Nanosecond),
+	"us": uint64(Microsecond),
+	"µs": uint64(Microsecond), // U+00B5 = micro symbol
+	"μs": uint64(Microsecond), // U+03BC = Greek letter mu
+	"ms": uint64(Millisecond),
+	"s":  uint64(Second),
+	"m":  uint64(Minute),
+	"h":  uint64(Hour),
+}
+
+// ParseDuration parses a duration string.
+// A duration string is a possibly signed sequence of
+// decimal numbers, each with optional fraction and a unit suffix,
+// such as "300ms", "-1.5h" or "2h45m".
+// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
+func ParseDuration(s string) (Duration, error) {
+	// [-+]?([0-9]*(\.[0-9]*)?[a-z]+)+
+	orig := s
+	var d uint64
+	neg := false
+
+	// Consume [-+]?
+	if s != "" {
+		c := s[0]
+		if c == '-' || c == '+' {
+			neg = c == '-'
+			s = s[1:]
+		}
+	}
+	// Special case: if all that is left is "0", this is zero.
+	if s == "0" {
+		return 0, nil
+	}
+	if s == "" {
+		return 0, errors.New("time: invalid duration " + quote(orig))
+	}
+	for s != "" {
+		var (
+			v, f  uint64      // integers before, after decimal point
+			scale float64 = 1 // value = v + f/scale
+		)
+
+		var err error
+
+		// The next character must be [0-9.]
+		if !(s[0] == '.' || '0' <= s[0] && s[0] <= '9') {
+			return 0, errors.New("time: invalid duration " + quote(orig))
+		}
+		// Consume [0-9]*
+		pl := len(s)
+		v, s, err = leadingInt(s)
+		if err != nil {
+			return 0, errors.New("time: invalid duration " + quote(orig))
+		}
+		pre := pl != len(s) // whether we consumed anything before a period
+
+		// Consume (\.[0-9]*)?
+		post := false
+		if s != "" && s[0] == '.' {
+			s = s[1:]
+			pl := len(s)
+			f, scale, s = leadingFraction(s)
+			post = pl != len(s)
+		}
+		if !pre && !post {
+			// no digits (e.g. ".s" or "-.s")
+			return 0, errors.New("time: invalid duration " + quote(orig))
+		}
+
+		// Consume unit.
+		i := 0
+		for ; i < len(s); i++ {
+			c := s[i]
+			if c == '.' || '0' <= c && c <= '9' {
+				break
+			}
+		}
+		if i == 0 {
+			return 0, errors.New("time: missing unit in duration " + quote(orig))
+		}
+		u := s[:i]
+		s = s[i:]
+		unit, ok := unitMap[u]
+		if !ok {
+			return 0, errors.New("time: unknown unit " + quote(u) + " in duration " + quote(orig))
+		}
+		if v > 1<<63/unit {
+			// overflow
+			return 0, errors.New("time: invalid duration " + quote(orig))
+		}
+		v *= unit
+		if f > 0 {
+			// float64 is needed to be nanosecond accurate for fractions of hours.
+			// v >= 0 && (f*unit/scale) <= 3.6e+12 (ns/h, h is the largest unit)
+			v += uint64(float64(f) * (float64(unit) / scale))
+			if v > 1<<63 {
+				// overflow
+				return 0, errors.New("time: invalid duration " + quote(orig))
+			}
+		}
+		d += v
+		if d > 1<<63 {
+			return 0, errors.New("time: invalid duration " + quote(orig))
+		}
+	}
+	if neg {
+		return -Duration(d), nil
+	}
+	if d > 1<<63-1 {
+		return 0, errors.New("time: invalid duration " + quote(orig))
+	}
+	return Duration(d), nil
+}
diff --git a/src/time/format_rfc3339.go b/src/time/format_rfc3339.go
new file mode 100644
index 0000000..1151666
--- /dev/null
+++ b/src/time/format_rfc3339.go
@@ -0,0 +1,188 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+import "errors"
+
+// RFC 3339 is the most commonly used format.
+//
+// It is implicitly used by the Time.(Marshal|Unmarshal)(Text|JSON) methods.
+// Also, according to analysis on https://go.dev/issue/52746,
+// RFC 3339 accounts for 57% of all explicitly specified time formats,
+// with the second most popular format only being used 8% of the time.
+// The overwhelming use of RFC 3339 compared to all other formats justifies
+// the addition of logic to optimize formatting and parsing.
+
+func (t Time) appendFormatRFC3339(b []byte, nanos bool) []byte {
+	_, offset, abs := t.locabs()
+
+	// Format date.
+	year, month, day, _ := absDate(abs, true)
+	b = appendInt(b, year, 4)
+	b = append(b, '-')
+	b = appendInt(b, int(month), 2)
+	b = append(b, '-')
+	b = appendInt(b, day, 2)
+
+	b = append(b, 'T')
+
+	// Format time.
+	hour, min, sec := absClock(abs)
+	b = appendInt(b, hour, 2)
+	b = append(b, ':')
+	b = appendInt(b, min, 2)
+	b = append(b, ':')
+	b = appendInt(b, sec, 2)
+
+	if nanos {
+		std := stdFracSecond(stdFracSecond9, 9, '.')
+		b = appendNano(b, t.Nanosecond(), std)
+	}
+
+	if offset == 0 {
+		return append(b, 'Z')
+	}
+
+	// Format zone.
+	zone := offset / 60 // convert to minutes
+	if zone < 0 {
+		b = append(b, '-')
+		zone = -zone
+	} else {
+		b = append(b, '+')
+	}
+	b = appendInt(b, zone/60, 2)
+	b = append(b, ':')
+	b = appendInt(b, zone%60, 2)
+	return b
+}
+
+func (t Time) appendStrictRFC3339(b []byte) ([]byte, error) {
+	n0 := len(b)
+	b = t.appendFormatRFC3339(b, true)
+
+	// Not all valid Go timestamps can be serialized as valid RFC 3339.
+	// Explicitly check for these edge cases.
+	// See https://go.dev/issue/4556 and https://go.dev/issue/54580.
+	num2 := func(b []byte) byte { return 10*(b[0]-'0') + (b[1] - '0') }
+	switch {
+	case b[n0+len("9999")] != '-': // year must be exactly 4 digits wide
+		return b, errors.New("year outside of range [0,9999]")
+	case b[len(b)-1] != 'Z':
+		c := b[len(b)-len("Z07:00")]
+		if ('0' <= c && c <= '9') || num2(b[len(b)-len("07:00"):]) >= 24 {
+			return b, errors.New("timezone hour outside of range [0,23]")
+		}
+	}
+	return b, nil
+}
+
+func parseRFC3339[bytes []byte | string](s bytes, local *Location) (Time, bool) {
+	// parseUint parses s as an unsigned decimal integer and
+	// verifies that it is within some range.
+	// If it is invalid or out-of-range,
+	// it sets ok to false and returns the min value.
+	ok := true
+	parseUint := func(s bytes, min, max int) (x int) {
+		for _, c := range []byte(s) {
+			if c < '0' || '9' < c {
+				ok = false
+				return min
+			}
+			x = x*10 + int(c) - '0'
+		}
+		if x < min || max < x {
+			ok = false
+			return min
+		}
+		return x
+	}
+
+	// Parse the date and time.
+	if len(s) < len("2006-01-02T15:04:05") {
+		return Time{}, false
+	}
+	year := parseUint(s[0:4], 0, 9999)                       // e.g., 2006
+	month := parseUint(s[5:7], 1, 12)                        // e.g., 01
+	day := parseUint(s[8:10], 1, daysIn(Month(month), year)) // e.g., 02
+	hour := parseUint(s[11:13], 0, 23)                       // e.g., 15
+	min := parseUint(s[14:16], 0, 59)                        // e.g., 04
+	sec := parseUint(s[17:19], 0, 59)                        // e.g., 05
+	if !ok || !(s[4] == '-' && s[7] == '-' && s[10] == 'T' && s[13] == ':' && s[16] == ':') {
+		return Time{}, false
+	}
+	s = s[19:]
+
+	// Parse the fractional second.
+	var nsec int
+	if len(s) >= 2 && s[0] == '.' && isDigit(s, 1) {
+		n := 2
+		for ; n < len(s) && isDigit(s, n); n++ {
+		}
+		nsec, _, _ = parseNanoseconds(s, n)
+		s = s[n:]
+	}
+
+	// Parse the time zone.
+	t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
+	if len(s) != 1 || s[0] != 'Z' {
+		if len(s) != len("-07:00") {
+			return Time{}, false
+		}
+		hr := parseUint(s[1:3], 0, 23) // e.g., 07
+		mm := parseUint(s[4:6], 0, 59) // e.g., 00
+		if !ok || !((s[0] == '-' || s[0] == '+') && s[3] == ':') {
+			return Time{}, false
+		}
+		zoneOffset := (hr*60 + mm) * 60
+		if s[0] == '-' {
+			zoneOffset *= -1
+		}
+		t.addSec(-int64(zoneOffset))
+
+		// Use local zone with the given offset if possible.
+		if _, offset, _, _, _ := local.lookup(t.unixSec()); offset == zoneOffset {
+			t.setLoc(local)
+		} else {
+			t.setLoc(FixedZone("", zoneOffset))
+		}
+	}
+	return t, true
+}
+
+func parseStrictRFC3339(b []byte) (Time, error) {
+	t, ok := parseRFC3339(b, Local)
+	if !ok {
+		t, err := Parse(RFC3339, string(b))
+		if err != nil {
+			return Time{}, err
+		}
+
+		// The parse template syntax cannot correctly validate RFC 3339.
+		// Explicitly check for cases that Parse is unable to validate for.
+		// See https://go.dev/issue/54580.
+		num2 := func(b []byte) byte { return 10*(b[0]-'0') + (b[1] - '0') }
+		switch {
+		// TODO(https://go.dev/issue/54580): Strict parsing is disabled for now.
+		// Enable this again with a GODEBUG opt-out.
+		case true:
+			return t, nil
+		case b[len("2006-01-02T")+1] == ':': // hour must be two digits
+			return Time{}, &ParseError{RFC3339, string(b), "15", string(b[len("2006-01-02T"):][:1]), ""}
+		case b[len("2006-01-02T15:04:05")] == ',': // sub-second separator must be a period
+			return Time{}, &ParseError{RFC3339, string(b), ".", ",", ""}
+		case b[len(b)-1] != 'Z':
+			switch {
+			case num2(b[len(b)-len("07:00"):]) >= 24: // timezone hour must be in range
+				return Time{}, &ParseError{RFC3339, string(b), "Z07:00", string(b[len(b)-len("Z07:00"):]), ": timezone hour out of range"}
+			case num2(b[len(b)-len("00"):]) >= 60: // timezone minute must be in range
+				return Time{}, &ParseError{RFC3339, string(b), "Z07:00", string(b[len(b)-len("Z07:00"):]), ": timezone minute out of range"}
+			}
+		default: // unknown error; should not occur
+			return Time{}, &ParseError{RFC3339, string(b), RFC3339, string(b), ""}
+		}
+	}
+	return t, nil
+}
diff --git a/src/time/format_test.go b/src/time/format_test.go
new file mode 100644
index 0000000..8a26eaa
--- /dev/null
+++ b/src/time/format_test.go
@@ -0,0 +1,1066 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+	"testing"
+	"testing/quick"
+	. "time"
+)
+
+var nextStdChunkTests = []string{
+	"(2006)-(01)-(02)T(15):(04):(05)(Z07:00)",
+	"(2006)-(01)-(02) (002) (15):(04):(05)",
+	"(2006)-(01) (002) (15):(04):(05)",
+	"(2006)-(002) (15):(04):(05)",
+	"(2006)(002)(01) (15):(04):(05)",
+	"(2006)(002)(04) (15):(04):(05)",
+}
+
+func TestNextStdChunk(t *testing.T) {
+	// Most bugs in Parse or Format boil down to problems with
+	// the exact detection of format chunk boundaries in the
+	// helper function nextStdChunk (here called as NextStdChunk).
+	// This test checks nextStdChunk's behavior directly,
+	// instead of needing to test it only indirectly through Parse/Format.
+
+	// markChunks returns format with each detected
+	// 'format chunk' parenthesized.
+	// For example showChunks("2006-01-02") == "(2006)-(01)-(02)".
+	markChunks := func(format string) string {
+		// Note that NextStdChunk and StdChunkNames
+		// are not part of time's public API.
+		// They are exported in export_test for this test.
+		out := ""
+		for s := format; s != ""; {
+			prefix, std, suffix := NextStdChunk(s)
+			out += prefix
+			if std > 0 {
+				out += "(" + StdChunkNames[std] + ")"
+			}
+			s = suffix
+		}
+		return out
+	}
+
+	noParens := func(r rune) rune {
+		if r == '(' || r == ')' {
+			return -1
+		}
+		return r
+	}
+
+	for _, marked := range nextStdChunkTests {
+		// marked is an expected output from markChunks.
+		// If we delete the parens and pass it through markChunks,
+		// we should get the original back.
+		format := strings.Map(noParens, marked)
+		out := markChunks(format)
+		if out != marked {
+			t.Errorf("nextStdChunk parses %q as %q, want %q", format, out, marked)
+		}
+	}
+}
+
+type TimeFormatTest struct {
+	time           Time
+	formattedValue string
+}
+
+var rfc3339Formats = []TimeFormatTest{
+	{Date(2008, 9, 17, 20, 4, 26, 0, UTC), "2008-09-17T20:04:26Z"},
+	{Date(1994, 9, 17, 20, 4, 26, 0, FixedZone("EST", -18000)), "1994-09-17T20:04:26-05:00"},
+	{Date(2000, 12, 26, 1, 15, 6, 0, FixedZone("OTO", 15600)), "2000-12-26T01:15:06+04:20"},
+}
+
+func TestRFC3339Conversion(t *testing.T) {
+	for _, f := range rfc3339Formats {
+		if f.time.Format(RFC3339) != f.formattedValue {
+			t.Error("RFC3339:")
+			t.Errorf("  want=%+v", f.formattedValue)
+			t.Errorf("  have=%+v", f.time.Format(RFC3339))
+		}
+	}
+}
+
+func TestAppendInt(t *testing.T) {
+	tests := []struct {
+		in    int
+		width int
+		want  string
+	}{
+		{0, 0, "0"},
+		{0, 1, "0"},
+		{0, 2, "00"},
+		{0, 3, "000"},
+		{1, 0, "1"},
+		{1, 1, "1"},
+		{1, 2, "01"},
+		{1, 3, "001"},
+		{-1, 0, "-1"},
+		{-1, 1, "-1"},
+		{-1, 2, "-01"},
+		{-1, 3, "-001"},
+		{99, 2, "99"},
+		{100, 2, "100"},
+		{1, 4, "0001"},
+		{12, 4, "0012"},
+		{123, 4, "0123"},
+		{1234, 4, "1234"},
+		{12345, 4, "12345"},
+		{1, 5, "00001"},
+		{12, 5, "00012"},
+		{123, 5, "00123"},
+		{1234, 5, "01234"},
+		{12345, 5, "12345"},
+		{123456, 5, "123456"},
+		{0, 9, "000000000"},
+		{123, 9, "000000123"},
+		{123456, 9, "000123456"},
+		{123456789, 9, "123456789"},
+	}
+	var got []byte
+	for _, tt := range tests {
+		got = AppendInt(got[:0], tt.in, tt.width)
+		if string(got) != tt.want {
+			t.Errorf("appendInt(%d, %d) = %s, want %s", tt.in, tt.width, got, tt.want)
+		}
+	}
+}
+
+type FormatTest struct {
+	name   string
+	format string
+	result string
+}
+
+var formatTests = []FormatTest{
+	{"ANSIC", ANSIC, "Wed Feb  4 21:00:57 2009"},
+	{"UnixDate", UnixDate, "Wed Feb  4 21:00:57 PST 2009"},
+	{"RubyDate", RubyDate, "Wed Feb 04 21:00:57 -0800 2009"},
+	{"RFC822", RFC822, "04 Feb 09 21:00 PST"},
+	{"RFC850", RFC850, "Wednesday, 04-Feb-09 21:00:57 PST"},
+	{"RFC1123", RFC1123, "Wed, 04 Feb 2009 21:00:57 PST"},
+	{"RFC1123Z", RFC1123Z, "Wed, 04 Feb 2009 21:00:57 -0800"},
+	{"RFC3339", RFC3339, "2009-02-04T21:00:57-08:00"},
+	{"RFC3339Nano", RFC3339Nano, "2009-02-04T21:00:57.0123456-08:00"},
+	{"Kitchen", Kitchen, "9:00PM"},
+	{"am/pm", "3pm", "9pm"},
+	{"AM/PM", "3PM", "9PM"},
+	{"two-digit year", "06 01 02", "09 02 04"},
+	// Three-letter months and days must not be followed by lower-case letter.
+	{"Janet", "Hi Janet, the Month is January", "Hi Janet, the Month is February"},
+	// Time stamps, Fractional seconds.
+	{"Stamp", Stamp, "Feb  4 21:00:57"},
+	{"StampMilli", StampMilli, "Feb  4 21:00:57.012"},
+	{"StampMicro", StampMicro, "Feb  4 21:00:57.012345"},
+	{"StampNano", StampNano, "Feb  4 21:00:57.012345600"},
+	{"DateTime", DateTime, "2009-02-04 21:00:57"},
+	{"DateOnly", DateOnly, "2009-02-04"},
+	{"TimeOnly", TimeOnly, "21:00:57"},
+	{"YearDay", "Jan  2 002 __2 2", "Feb  4 035  35 4"},
+	{"Year", "2006 6 06 _6 __6 ___6", "2009 6 09 _6 __6 ___6"},
+	{"Month", "Jan January 1 01 _1", "Feb February 2 02 _2"},
+	{"DayOfMonth", "2 02 _2 __2", "4 04  4  35"},
+	{"DayOfWeek", "Mon Monday", "Wed Wednesday"},
+	{"Hour", "15 3 03 _3", "21 9 09 _9"},
+	{"Minute", "4 04 _4", "0 00 _0"},
+	{"Second", "5 05 _5", "57 57 _57"},
+}
+
+func TestFormat(t *testing.T) {
+	// The numeric time represents Thu Feb  4 21:00:57.012345600 PST 2009
+	time := Unix(0, 1233810057012345600)
+	for _, test := range formatTests {
+		result := time.Format(test.format)
+		if result != test.result {
+			t.Errorf("%s expected %q got %q", test.name, test.result, result)
+		}
+	}
+}
+
+var goStringTests = []struct {
+	in   Time
+	want string
+}{
+	{Date(2009, February, 5, 5, 0, 57, 12345600, UTC),
+		"time.Date(2009, time.February, 5, 5, 0, 57, 12345600, time.UTC)"},
+	{Date(2009, February, 5, 5, 0, 57, 12345600, Local),
+		"time.Date(2009, time.February, 5, 5, 0, 57, 12345600, time.Local)"},
+	{Date(2009, February, 5, 5, 0, 57, 12345600, FixedZone("Europe/Berlin", 3*60*60)),
+		`time.Date(2009, time.February, 5, 5, 0, 57, 12345600, time.Location("Europe/Berlin"))`,
+	},
+	{Date(2009, February, 5, 5, 0, 57, 12345600, FixedZone("Non-ASCII character ⏰", 3*60*60)),
+		`time.Date(2009, time.February, 5, 5, 0, 57, 12345600, time.Location("Non-ASCII character \xe2\x8f\xb0"))`,
+	},
+}
+
+func TestGoString(t *testing.T) {
+	// The numeric time represents Thu Feb  4 21:00:57.012345600 PST 2009
+	for _, tt := range goStringTests {
+		if tt.in.GoString() != tt.want {
+			t.Errorf("GoString (%q): got %q want %q", tt.in, tt.in.GoString(), tt.want)
+		}
+	}
+}
+
+// issue 12440.
+func TestFormatSingleDigits(t *testing.T) {
+	time := Date(2001, 2, 3, 4, 5, 6, 700000000, UTC)
+	test := FormatTest{"single digit format", "3:4:5", "4:5:6"}
+	result := time.Format(test.format)
+	if result != test.result {
+		t.Errorf("%s expected %q got %q", test.name, test.result, result)
+	}
+}
+
+func TestFormatShortYear(t *testing.T) {
+	years := []int{
+		-100001, -100000, -99999,
+		-10001, -10000, -9999,
+		-1001, -1000, -999,
+		-101, -100, -99,
+		-11, -10, -9,
+		-1, 0, 1,
+		9, 10, 11,
+		99, 100, 101,
+		999, 1000, 1001,
+		9999, 10000, 10001,
+		99999, 100000, 100001,
+	}
+
+	for _, y := range years {
+		time := Date(y, January, 1, 0, 0, 0, 0, UTC)
+		result := time.Format("2006.01.02")
+		var want string
+		if y < 0 {
+			// The 4 in %04d counts the - sign, so print -y instead
+			// and introduce our own - sign.
+			want = fmt.Sprintf("-%04d.%02d.%02d", -y, 1, 1)
+		} else {
+			want = fmt.Sprintf("%04d.%02d.%02d", y, 1, 1)
+		}
+		if result != want {
+			t.Errorf("(jan 1 %d).Format(\"2006.01.02\") = %q, want %q", y, result, want)
+		}
+	}
+}
+
+type ParseTest struct {
+	name       string
+	format     string
+	value      string
+	hasTZ      bool // contains a time zone
+	hasWD      bool // contains a weekday
+	yearSign   int  // sign of year, -1 indicates the year is not present in the format
+	fracDigits int  // number of digits of fractional second
+}
+
+var parseTests = []ParseTest{
+	{"ANSIC", ANSIC, "Thu Feb  4 21:00:57 2010", false, true, 1, 0},
+	{"UnixDate", UnixDate, "Thu Feb  4 21:00:57 PST 2010", true, true, 1, 0},
+	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 -0800 2010", true, true, 1, 0},
+	{"RFC850", RFC850, "Thursday, 04-Feb-10 21:00:57 PST", true, true, 1, 0},
+	{"RFC1123", RFC1123, "Thu, 04 Feb 2010 21:00:57 PST", true, true, 1, 0},
+	{"RFC1123", RFC1123, "Thu, 04 Feb 2010 22:00:57 PDT", true, true, 1, 0},
+	{"RFC1123Z", RFC1123Z, "Thu, 04 Feb 2010 21:00:57 -0800", true, true, 1, 0},
+	{"RFC3339", RFC3339, "2010-02-04T21:00:57-08:00", true, false, 1, 0},
+	{"custom: \"2006-01-02 15:04:05-07\"", "2006-01-02 15:04:05-07", "2010-02-04 21:00:57-08", true, false, 1, 0},
+	// Optional fractional seconds.
+	{"ANSIC", ANSIC, "Thu Feb  4 21:00:57.0 2010", false, true, 1, 1},
+	{"UnixDate", UnixDate, "Thu Feb  4 21:00:57.01 PST 2010", true, true, 1, 2},
+	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57.012 -0800 2010", true, true, 1, 3},
+	{"RFC850", RFC850, "Thursday, 04-Feb-10 21:00:57.0123 PST", true, true, 1, 4},
+	{"RFC1123", RFC1123, "Thu, 04 Feb 2010 21:00:57.01234 PST", true, true, 1, 5},
+	{"RFC1123Z", RFC1123Z, "Thu, 04 Feb 2010 21:00:57.01234 -0800", true, true, 1, 5},
+	{"RFC3339", RFC3339, "2010-02-04T21:00:57.012345678-08:00", true, false, 1, 9},
+	{"custom: \"2006-01-02 15:04:05\"", "2006-01-02 15:04:05", "2010-02-04 21:00:57.0", false, false, 1, 0},
+	// Amount of white space should not matter.
+	{"ANSIC", ANSIC, "Thu Feb 4 21:00:57 2010", false, true, 1, 0},
+	{"ANSIC", ANSIC, "Thu      Feb     4     21:00:57     2010", false, true, 1, 0},
+	// Case should not matter
+	{"ANSIC", ANSIC, "THU FEB 4 21:00:57 2010", false, true, 1, 0},
+	{"ANSIC", ANSIC, "thu feb 4 21:00:57 2010", false, true, 1, 0},
+	// Fractional seconds.
+	{"millisecond:: dot separator", "Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 21:00:57.012 2010", false, true, 1, 3},
+	{"microsecond:: dot separator", "Mon Jan _2 15:04:05.000000 2006", "Thu Feb  4 21:00:57.012345 2010", false, true, 1, 6},
+	{"nanosecond:: dot separator", "Mon Jan _2 15:04:05.000000000 2006", "Thu Feb  4 21:00:57.012345678 2010", false, true, 1, 9},
+	{"millisecond:: comma separator", "Mon Jan _2 15:04:05,000 2006", "Thu Feb  4 21:00:57.012 2010", false, true, 1, 3},
+	{"microsecond:: comma separator", "Mon Jan _2 15:04:05,000000 2006", "Thu Feb  4 21:00:57.012345 2010", false, true, 1, 6},
+	{"nanosecond:: comma separator", "Mon Jan _2 15:04:05,000000000 2006", "Thu Feb  4 21:00:57.012345678 2010", false, true, 1, 9},
+
+	// Leading zeros in other places should not be taken as fractional seconds.
+	{"zero1", "2006.01.02.15.04.05.0", "2010.02.04.21.00.57.0", false, false, 1, 1},
+	{"zero2", "2006.01.02.15.04.05.00", "2010.02.04.21.00.57.01", false, false, 1, 2},
+	// Month and day names only match when not followed by a lower-case letter.
+	{"Janet", "Hi Janet, the Month is January: Jan _2 15:04:05 2006", "Hi Janet, the Month is February: Feb  4 21:00:57 2010", false, true, 1, 0},
+
+	// GMT with offset.
+	{"GMT-8", UnixDate, "Fri Feb  5 05:00:57 GMT-8 2010", true, true, 1, 0},
+
+	// Accept any number of fractional second digits (including none) for .999...
+	// In Go 1, .999... was completely ignored in the format, meaning the first two
+	// cases would succeed, but the next four would not. Go 1.1 accepts all six.
+	// decimal "." separator.
+	{"", "2006-01-02 15:04:05.9999 -0700 MST", "2010-02-04 21:00:57 -0800 PST", true, false, 1, 0},
+	{"", "2006-01-02 15:04:05.999999999 -0700 MST", "2010-02-04 21:00:57 -0800 PST", true, false, 1, 0},
+	{"", "2006-01-02 15:04:05.9999 -0700 MST", "2010-02-04 21:00:57.0123 -0800 PST", true, false, 1, 4},
+	{"", "2006-01-02 15:04:05.999999999 -0700 MST", "2010-02-04 21:00:57.0123 -0800 PST", true, false, 1, 4},
+	{"", "2006-01-02 15:04:05.9999 -0700 MST", "2010-02-04 21:00:57.012345678 -0800 PST", true, false, 1, 9},
+	{"", "2006-01-02 15:04:05.999999999 -0700 MST", "2010-02-04 21:00:57.012345678 -0800 PST", true, false, 1, 9},
+	// comma "," separator.
+	{"", "2006-01-02 15:04:05,9999 -0700 MST", "2010-02-04 21:00:57 -0800 PST", true, false, 1, 0},
+	{"", "2006-01-02 15:04:05,999999999 -0700 MST", "2010-02-04 21:00:57 -0800 PST", true, false, 1, 0},
+	{"", "2006-01-02 15:04:05,9999 -0700 MST", "2010-02-04 21:00:57.0123 -0800 PST", true, false, 1, 4},
+	{"", "2006-01-02 15:04:05,999999999 -0700 MST", "2010-02-04 21:00:57.0123 -0800 PST", true, false, 1, 4},
+	{"", "2006-01-02 15:04:05,9999 -0700 MST", "2010-02-04 21:00:57.012345678 -0800 PST", true, false, 1, 9},
+	{"", "2006-01-02 15:04:05,999999999 -0700 MST", "2010-02-04 21:00:57.012345678 -0800 PST", true, false, 1, 9},
+
+	// issue 4502.
+	{"", StampNano, "Feb  4 21:00:57.012345678", false, false, -1, 9},
+	{"", "Jan _2 15:04:05.999", "Feb  4 21:00:57.012300000", false, false, -1, 4},
+	{"", "Jan _2 15:04:05.999", "Feb  4 21:00:57.012345678", false, false, -1, 9},
+	{"", "Jan _2 15:04:05.999999999", "Feb  4 21:00:57.0123", false, false, -1, 4},
+	{"", "Jan _2 15:04:05.999999999", "Feb  4 21:00:57.012345678", false, false, -1, 9},
+
+	// Day of year.
+	{"", "2006-01-02 002 15:04:05", "2010-02-04 035 21:00:57", false, false, 1, 0},
+	{"", "2006-01 002 15:04:05", "2010-02 035 21:00:57", false, false, 1, 0},
+	{"", "2006-002 15:04:05", "2010-035 21:00:57", false, false, 1, 0},
+	{"", "200600201 15:04:05", "201003502 21:00:57", false, false, 1, 0},
+	{"", "200600204 15:04:05", "201003504 21:00:57", false, false, 1, 0},
+}
+
+func TestParse(t *testing.T) {
+	for _, test := range parseTests {
+		time, err := Parse(test.format, test.value)
+		if err != nil {
+			t.Errorf("%s error: %v", test.name, err)
+		} else {
+			checkTime(time, &test, t)
+		}
+	}
+}
+
+// All parsed with ANSIC.
+var dayOutOfRangeTests = []struct {
+	date string
+	ok   bool
+}{
+	{"Thu Jan 99 21:00:57 2010", false},
+	{"Thu Jan 31 21:00:57 2010", true},
+	{"Thu Jan 32 21:00:57 2010", false},
+	{"Thu Feb 28 21:00:57 2012", true},
+	{"Thu Feb 29 21:00:57 2012", true},
+	{"Thu Feb 29 21:00:57 2010", false},
+	{"Thu Mar 31 21:00:57 2010", true},
+	{"Thu Mar 32 21:00:57 2010", false},
+	{"Thu Apr 30 21:00:57 2010", true},
+	{"Thu Apr 31 21:00:57 2010", false},
+	{"Thu May 31 21:00:57 2010", true},
+	{"Thu May 32 21:00:57 2010", false},
+	{"Thu Jun 30 21:00:57 2010", true},
+	{"Thu Jun 31 21:00:57 2010", false},
+	{"Thu Jul 31 21:00:57 2010", true},
+	{"Thu Jul 32 21:00:57 2010", false},
+	{"Thu Aug 31 21:00:57 2010", true},
+	{"Thu Aug 32 21:00:57 2010", false},
+	{"Thu Sep 30 21:00:57 2010", true},
+	{"Thu Sep 31 21:00:57 2010", false},
+	{"Thu Oct 31 21:00:57 2010", true},
+	{"Thu Oct 32 21:00:57 2010", false},
+	{"Thu Nov 30 21:00:57 2010", true},
+	{"Thu Nov 31 21:00:57 2010", false},
+	{"Thu Dec 31 21:00:57 2010", true},
+	{"Thu Dec 32 21:00:57 2010", false},
+	{"Thu Dec 00 21:00:57 2010", false},
+}
+
+func TestParseDayOutOfRange(t *testing.T) {
+	for _, test := range dayOutOfRangeTests {
+		_, err := Parse(ANSIC, test.date)
+		switch {
+		case test.ok && err == nil:
+			// OK
+		case !test.ok && err != nil:
+			if !strings.Contains(err.Error(), "day out of range") {
+				t.Errorf("%q: expected 'day' error, got %v", test.date, err)
+			}
+		case test.ok && err != nil:
+			t.Errorf("%q: unexpected error: %v", test.date, err)
+		case !test.ok && err == nil:
+			t.Errorf("%q: expected 'day' error, got none", test.date)
+		}
+	}
+}
+
+// TestParseInLocation checks that the Parse and ParseInLocation
+// functions do not get confused by the fact that AST (Arabia Standard
+// Time) and AST (Atlantic Standard Time) are different time zones,
+// even though they have the same abbreviation.
+//
+// ICANN has been slowly phasing out invented abbreviation in favor of
+// numeric time zones (for example, the Asia/Baghdad time zone
+// abbreviation got changed from AST to +03 in the 2017a tzdata
+// release); but we still want to make sure that the time package does
+// not get confused on systems with slightly older tzdata packages.
+func TestParseInLocation(t *testing.T) {
+
+	baghdad, err := LoadLocation("Asia/Baghdad")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var t1, t2 Time
+
+	t1, err = ParseInLocation("Jan 02 2006 MST", "Feb 01 2013 AST", baghdad)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, offset := t1.Zone()
+
+	// A zero offset means that ParseInLocation did not recognize the
+	// 'AST' abbreviation as matching the current location (Baghdad,
+	// where we'd expect a +03 hrs offset); likely because we're using
+	// a recent tzdata release (2017a or newer).
+	// If it happens, skip the Baghdad test.
+	if offset != 0 {
+		t2 = Date(2013, February, 1, 00, 00, 00, 0, baghdad)
+		if t1 != t2 {
+			t.Fatalf("ParseInLocation(Feb 01 2013 AST, Baghdad) = %v, want %v", t1, t2)
+		}
+		if offset != 3*60*60 {
+			t.Fatalf("ParseInLocation(Feb 01 2013 AST, Baghdad).Zone = _, %d, want _, %d", offset, 3*60*60)
+		}
+	}
+
+	blancSablon, err := LoadLocation("America/Blanc-Sablon")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// In this case 'AST' means 'Atlantic Standard Time', and we
+	// expect the abbreviation to correctly match the american
+	// location.
+	t1, err = ParseInLocation("Jan 02 2006 MST", "Feb 01 2013 AST", blancSablon)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t2 = Date(2013, February, 1, 00, 00, 00, 0, blancSablon)
+	if t1 != t2 {
+		t.Fatalf("ParseInLocation(Feb 01 2013 AST, Blanc-Sablon) = %v, want %v", t1, t2)
+	}
+	_, offset = t1.Zone()
+	if offset != -4*60*60 {
+		t.Fatalf("ParseInLocation(Feb 01 2013 AST, Blanc-Sablon).Zone = _, %d, want _, %d", offset, -4*60*60)
+	}
+}
+
+func TestLoadLocationZipFile(t *testing.T) {
+	undo := DisablePlatformSources()
+	defer undo()
+
+	_, err := LoadLocation("Australia/Sydney")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+var rubyTests = []ParseTest{
+	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 -0800 2010", true, true, 1, 0},
+	// Ignore the time zone in the test. If it parses, it'll be OK.
+	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 -0000 2010", false, true, 1, 0},
+	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 +0000 2010", false, true, 1, 0},
+	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 +1130 2010", false, true, 1, 0},
+}
+
+// Problematic time zone format needs special tests.
+func TestRubyParse(t *testing.T) {
+	for _, test := range rubyTests {
+		time, err := Parse(test.format, test.value)
+		if err != nil {
+			t.Errorf("%s error: %v", test.name, err)
+		} else {
+			checkTime(time, &test, t)
+		}
+	}
+}
+
+func checkTime(time Time, test *ParseTest, t *testing.T) {
+	// The time should be Thu Feb  4 21:00:57 PST 2010
+	if test.yearSign >= 0 && test.yearSign*time.Year() != 2010 {
+		t.Errorf("%s: bad year: %d not %d", test.name, time.Year(), 2010)
+	}
+	if time.Month() != February {
+		t.Errorf("%s: bad month: %s not %s", test.name, time.Month(), February)
+	}
+	if time.Day() != 4 {
+		t.Errorf("%s: bad day: %d not %d", test.name, time.Day(), 4)
+	}
+	if time.Hour() != 21 {
+		t.Errorf("%s: bad hour: %d not %d", test.name, time.Hour(), 21)
+	}
+	if time.Minute() != 0 {
+		t.Errorf("%s: bad minute: %d not %d", test.name, time.Minute(), 0)
+	}
+	if time.Second() != 57 {
+		t.Errorf("%s: bad second: %d not %d", test.name, time.Second(), 57)
+	}
+	// Nanoseconds must be checked against the precision of the input.
+	nanosec, err := strconv.ParseUint("012345678"[:test.fracDigits]+"000000000"[:9-test.fracDigits], 10, 0)
+	if err != nil {
+		panic(err)
+	}
+	if time.Nanosecond() != int(nanosec) {
+		t.Errorf("%s: bad nanosecond: %d not %d", test.name, time.Nanosecond(), nanosec)
+	}
+	name, offset := time.Zone()
+	if test.hasTZ && offset != -28800 {
+		t.Errorf("%s: bad tz offset: %s %d not %d", test.name, name, offset, -28800)
+	}
+	if test.hasWD && time.Weekday() != Thursday {
+		t.Errorf("%s: bad weekday: %s not %s", test.name, time.Weekday(), Thursday)
+	}
+}
+
+func TestFormatAndParse(t *testing.T) {
+	const fmt = "Mon MST " + RFC3339 // all fields
+	f := func(sec int64) bool {
+		t1 := Unix(sec/2, 0)
+		if t1.Year() < 1000 || t1.Year() > 9999 || t1.Unix() != sec {
+			// not required to work
+			return true
+		}
+		t2, err := Parse(fmt, t1.Format(fmt))
+		if err != nil {
+			t.Errorf("error: %s", err)
+			return false
+		}
+		if t1.Unix() != t2.Unix() || t1.Nanosecond() != t2.Nanosecond() {
+			t.Errorf("FormatAndParse %d: %q(%d) %q(%d)", sec, t1, t1.Unix(), t2, t2.Unix())
+			return false
+		}
+		return true
+	}
+	f32 := func(sec int32) bool { return f(int64(sec)) }
+	cfg := &quick.Config{MaxCount: 10000}
+
+	// Try a reasonable date first, then the huge ones.
+	if err := quick.Check(f32, cfg); err != nil {
+		t.Fatal(err)
+	}
+	if err := quick.Check(f, cfg); err != nil {
+		t.Fatal(err)
+	}
+}
+
+type ParseTimeZoneTest struct {
+	value  string
+	length int
+	ok     bool
+}
+
+var parseTimeZoneTests = []ParseTimeZoneTest{
+	{"gmt hi there", 0, false},
+	{"GMT hi there", 3, true},
+	{"GMT+12 hi there", 6, true},
+	{"GMT+00 hi there", 6, true},
+	{"GMT+", 3, true},
+	{"GMT+3", 5, true},
+	{"GMT+a", 3, true},
+	{"GMT+3a", 5, true},
+	{"GMT-5 hi there", 5, true},
+	{"GMT-51 hi there", 3, true},
+	{"ChST hi there", 4, true},
+	{"MeST hi there", 4, true},
+	{"MSDx", 3, true},
+	{"MSDY", 0, false}, // four letters must end in T.
+	{"ESAST hi", 5, true},
+	{"ESASTT hi", 0, false}, // run of upper-case letters too long.
+	{"ESATY hi", 0, false},  // five letters must end in T.
+	{"WITA hi", 4, true},    // Issue #18251
+	// Issue #24071
+	{"+03 hi", 3, true},
+	{"-04 hi", 3, true},
+	// Issue #26032
+	{"+00", 3, true},
+	{"-11", 3, true},
+	{"-12", 3, true},
+	{"-23", 3, true},
+	{"-24", 0, false},
+	{"+13", 3, true},
+	{"+14", 3, true},
+	{"+23", 3, true},
+	{"+24", 0, false},
+}
+
+func TestParseTimeZone(t *testing.T) {
+	for _, test := range parseTimeZoneTests {
+		length, ok := ParseTimeZone(test.value)
+		if ok != test.ok {
+			t.Errorf("expected %t for %q got %t", test.ok, test.value, ok)
+		} else if length != test.length {
+			t.Errorf("expected %d for %q got %d", test.length, test.value, length)
+		}
+	}
+}
+
+type ParseErrorTest struct {
+	format string
+	value  string
+	expect string // must appear within the error
+}
+
+var parseErrorTests = []ParseErrorTest{
+	{ANSIC, "Feb  4 21:00:60 2010", `cannot parse "Feb  4 21:00:60 2010" as "Mon"`},
+	{ANSIC, "Thu Feb  4 21:00:57 @2010", `cannot parse "@2010" as "2006"`},
+	{ANSIC, "Thu Feb  4 21:00:60 2010", "second out of range"},
+	{ANSIC, "Thu Feb  4 21:61:57 2010", "minute out of range"},
+	{ANSIC, "Thu Feb  4 24:00:60 2010", "hour out of range"},
+	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59x01 2010", `cannot parse "x01 2010" as ".000"`},
+	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59.xxx 2010", `cannot parse ".xxx 2010" as ".000"`},
+	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59.-123 2010", "fractional second out of range"},
+	// issue 4502. StampNano requires exactly 9 digits of precision.
+	{StampNano, "Dec  7 11:22:01.000000", `cannot parse ".000000" as ".000000000"`},
+	{StampNano, "Dec  7 11:22:01.0000000000", `extra text: "0"`},
+	// issue 4493. Helpful errors.
+	{RFC3339, "2006-01-02T15:04:05Z07:00", `parsing time "2006-01-02T15:04:05Z07:00": extra text: "07:00"`},
+	{RFC3339, "2006-01-02T15:04_abc", `parsing time "2006-01-02T15:04_abc" as "2006-01-02T15:04:05Z07:00": cannot parse "_abc" as ":"`},
+	{RFC3339, "2006-01-02T15:04:05_abc", `parsing time "2006-01-02T15:04:05_abc" as "2006-01-02T15:04:05Z07:00": cannot parse "_abc" as "Z07:00"`},
+	{RFC3339, "2006-01-02T15:04:05Z_abc", `parsing time "2006-01-02T15:04:05Z_abc": extra text: "_abc"`},
+	// invalid second followed by optional fractional seconds
+	{RFC3339, "2010-02-04T21:00:67.012345678-08:00", "second out of range"},
+	// issue 54569
+	{RFC3339, "0000-01-01T00:00:.0+00:00", `parsing time "0000-01-01T00:00:.0+00:00" as "2006-01-02T15:04:05Z07:00": cannot parse ".0+00:00" as "05"`},
+	// issue 21113
+	{"_2 Jan 06 15:04 MST", "4 --- 00 00:00 GMT", `cannot parse "--- 00 00:00 GMT" as "Jan"`},
+	{"_2 January 06 15:04 MST", "4 --- 00 00:00 GMT", `cannot parse "--- 00 00:00 GMT" as "January"`},
+
+	// invalid or mismatched day-of-year
+	{"Jan _2 002 2006", "Feb  4 034 2006", "day-of-year does not match day"},
+	{"Jan _2 002 2006", "Feb  4 004 2006", "day-of-year does not match month"},
+
+	// issue 45391.
+	{`"2006-01-02T15:04:05Z07:00"`, "0", `parsing time "0" as "\"2006-01-02T15:04:05Z07:00\"": cannot parse "0" as "\""`},
+	{RFC3339, "\"", `parsing time "\"" as "2006-01-02T15:04:05Z07:00": cannot parse "\"" as "2006"`},
+
+	// issue 54570
+	{RFC3339, "0000-01-01T00:00:00+00:+0", `parsing time "0000-01-01T00:00:00+00:+0" as "2006-01-02T15:04:05Z07:00": cannot parse "+00:+0" as "Z07:00"`},
+	{RFC3339, "0000-01-01T00:00:00+-0:00", `parsing time "0000-01-01T00:00:00+-0:00" as "2006-01-02T15:04:05Z07:00": cannot parse "+-0:00" as "Z07:00"`},
+
+	// issue 56730
+	{"2006-01-02", "22-10-25", `parsing time "22-10-25" as "2006-01-02": cannot parse "22-10-25" as "2006"`},
+	{"06-01-02", "a2-10-25", `parsing time "a2-10-25" as "06-01-02": cannot parse "a2-10-25" as "06"`},
+	{"03:04PM", "12:03pM", `parsing time "12:03pM" as "03:04PM": cannot parse "pM" as "PM"`},
+	{"03:04pm", "12:03pM", `parsing time "12:03pM" as "03:04pm": cannot parse "pM" as "pm"`},
+}
+
+func TestParseErrors(t *testing.T) {
+	for _, test := range parseErrorTests {
+		_, err := Parse(test.format, test.value)
+		if err == nil {
+			t.Errorf("expected error for %q %q", test.format, test.value)
+		} else if !strings.Contains(err.Error(), test.expect) {
+			t.Errorf("expected error with %q for %q %q; got %s", test.expect, test.format, test.value, err)
+		}
+	}
+}
+
+func TestNoonIs12PM(t *testing.T) {
+	noon := Date(0, January, 1, 12, 0, 0, 0, UTC)
+	const expect = "12:00PM"
+	got := noon.Format("3:04PM")
+	if got != expect {
+		t.Errorf("got %q; expect %q", got, expect)
+	}
+	got = noon.Format("03:04PM")
+	if got != expect {
+		t.Errorf("got %q; expect %q", got, expect)
+	}
+}
+
+func TestMidnightIs12AM(t *testing.T) {
+	midnight := Date(0, January, 1, 0, 0, 0, 0, UTC)
+	expect := "12:00AM"
+	got := midnight.Format("3:04PM")
+	if got != expect {
+		t.Errorf("got %q; expect %q", got, expect)
+	}
+	got = midnight.Format("03:04PM")
+	if got != expect {
+		t.Errorf("got %q; expect %q", got, expect)
+	}
+}
+
+func Test12PMIsNoon(t *testing.T) {
+	noon, err := Parse("3:04PM", "12:00PM")
+	if err != nil {
+		t.Fatal("error parsing date:", err)
+	}
+	if noon.Hour() != 12 {
+		t.Errorf("got %d; expect 12", noon.Hour())
+	}
+	noon, err = Parse("03:04PM", "12:00PM")
+	if err != nil {
+		t.Fatal("error parsing date:", err)
+	}
+	if noon.Hour() != 12 {
+		t.Errorf("got %d; expect 12", noon.Hour())
+	}
+}
+
+func Test12AMIsMidnight(t *testing.T) {
+	midnight, err := Parse("3:04PM", "12:00AM")
+	if err != nil {
+		t.Fatal("error parsing date:", err)
+	}
+	if midnight.Hour() != 0 {
+		t.Errorf("got %d; expect 0", midnight.Hour())
+	}
+	midnight, err = Parse("03:04PM", "12:00AM")
+	if err != nil {
+		t.Fatal("error parsing date:", err)
+	}
+	if midnight.Hour() != 0 {
+		t.Errorf("got %d; expect 0", midnight.Hour())
+	}
+}
+
+// Check that a time without a Zone still produces a (numeric) time zone
+// when formatted with MST as a requested zone.
+func TestMissingZone(t *testing.T) {
+	time, err := Parse(RubyDate, "Thu Feb 02 16:10:03 -0500 2006")
+	if err != nil {
+		t.Fatal("error parsing date:", err)
+	}
+	expect := "Thu Feb  2 16:10:03 -0500 2006" // -0500 not EST
+	str := time.Format(UnixDate)               // uses MST as its time zone
+	if str != expect {
+		t.Errorf("got %s; expect %s", str, expect)
+	}
+}
+
+func TestMinutesInTimeZone(t *testing.T) {
+	time, err := Parse(RubyDate, "Mon Jan 02 15:04:05 +0123 2006")
+	if err != nil {
+		t.Fatal("error parsing date:", err)
+	}
+	expected := (1*60 + 23) * 60
+	_, offset := time.Zone()
+	if offset != expected {
+		t.Errorf("ZoneOffset = %d, want %d", offset, expected)
+	}
+}
+
+type SecondsTimeZoneOffsetTest struct {
+	format         string
+	value          string
+	expectedoffset int
+}
+
+var secondsTimeZoneOffsetTests = []SecondsTimeZoneOffsetTest{
+	{"2006-01-02T15:04:05-070000", "1871-01-01T05:33:02-003408", -(34*60 + 8)},
+	{"2006-01-02T15:04:05-07:00:00", "1871-01-01T05:33:02-00:34:08", -(34*60 + 8)},
+	{"2006-01-02T15:04:05-070000", "1871-01-01T05:33:02+003408", 34*60 + 8},
+	{"2006-01-02T15:04:05-07:00:00", "1871-01-01T05:33:02+00:34:08", 34*60 + 8},
+	{"2006-01-02T15:04:05Z070000", "1871-01-01T05:33:02-003408", -(34*60 + 8)},
+	{"2006-01-02T15:04:05Z07:00:00", "1871-01-01T05:33:02+00:34:08", 34*60 + 8},
+	{"2006-01-02T15:04:05-07", "1871-01-01T05:33:02+01", 1 * 60 * 60},
+	{"2006-01-02T15:04:05-07", "1871-01-01T05:33:02-02", -2 * 60 * 60},
+	{"2006-01-02T15:04:05Z07", "1871-01-01T05:33:02-02", -2 * 60 * 60},
+}
+
+func TestParseSecondsInTimeZone(t *testing.T) {
+	// should accept timezone offsets with seconds like: Zone America/New_York   -4:56:02 -      LMT     1883 Nov 18 12:03:58
+	for _, test := range secondsTimeZoneOffsetTests {
+		time, err := Parse(test.format, test.value)
+		if err != nil {
+			t.Fatal("error parsing date:", err)
+		}
+		_, offset := time.Zone()
+		if offset != test.expectedoffset {
+			t.Errorf("ZoneOffset = %d, want %d", offset, test.expectedoffset)
+		}
+	}
+}
+
+func TestFormatSecondsInTimeZone(t *testing.T) {
+	for _, test := range secondsTimeZoneOffsetTests {
+		d := Date(1871, 1, 1, 5, 33, 2, 0, FixedZone("LMT", test.expectedoffset))
+		timestr := d.Format(test.format)
+		if timestr != test.value {
+			t.Errorf("Format = %s, want %s", timestr, test.value)
+		}
+	}
+}
+
+// Issue 11334.
+func TestUnderscoreTwoThousand(t *testing.T) {
+	format := "15:04_20060102"
+	input := "14:38_20150618"
+	time, err := Parse(format, input)
+	if err != nil {
+		t.Error(err)
+	}
+	if y, m, d := time.Date(); y != 2015 || m != 6 || d != 18 {
+		t.Errorf("Incorrect y/m/d, got %d/%d/%d", y, m, d)
+	}
+	if h := time.Hour(); h != 14 {
+		t.Errorf("Incorrect hour, got %d", h)
+	}
+	if m := time.Minute(); m != 38 {
+		t.Errorf("Incorrect minute, got %d", m)
+	}
+}
+
+// Issue 29918, 29916
+func TestStd0xParseError(t *testing.T) {
+	tests := []struct {
+		format, value, valueElemPrefix string
+	}{
+		{"01 MST", "0 MST", "0"},
+		{"01 MST", "1 MST", "1"},
+		{RFC850, "Thursday, 04-Feb-1 21:00:57 PST", "1"},
+	}
+	for _, tt := range tests {
+		_, err := Parse(tt.format, tt.value)
+		if err == nil {
+			t.Errorf("Parse(%q, %q) did not fail as expected", tt.format, tt.value)
+		} else if perr, ok := err.(*ParseError); !ok {
+			t.Errorf("Parse(%q, %q) returned error type %T, expected ParseError", tt.format, tt.value, perr)
+		} else if !strings.Contains(perr.Error(), "cannot parse") || !strings.HasPrefix(perr.ValueElem, tt.valueElemPrefix) {
+			t.Errorf("Parse(%q, %q) returned wrong parsing error message: %v", tt.format, tt.value, perr)
+		}
+	}
+}
+
+var monthOutOfRangeTests = []struct {
+	value string
+	ok    bool
+}{
+	{"00-01", false},
+	{"13-01", false},
+	{"01-01", true},
+}
+
+func TestParseMonthOutOfRange(t *testing.T) {
+	for _, test := range monthOutOfRangeTests {
+		_, err := Parse("01-02", test.value)
+		switch {
+		case !test.ok && err != nil:
+			if !strings.Contains(err.Error(), "month out of range") {
+				t.Errorf("%q: expected 'month' error, got %v", test.value, err)
+			}
+		case test.ok && err != nil:
+			t.Errorf("%q: unexpected error: %v", test.value, err)
+		case !test.ok && err == nil:
+			t.Errorf("%q: expected 'month' error, got none", test.value)
+		}
+	}
+}
+
+// Issue 37387.
+func TestParseYday(t *testing.T) {
+	t.Parallel()
+	for i := 1; i <= 365; i++ {
+		d := fmt.Sprintf("2020-%03d", i)
+		tm, err := Parse("2006-002", d)
+		if err != nil {
+			t.Errorf("unexpected error for %s: %v", d, err)
+		} else if tm.Year() != 2020 || tm.YearDay() != i {
+			t.Errorf("got year %d yearday %d, want %d %d", tm.Year(), tm.YearDay(), 2020, i)
+		}
+	}
+}
+
+// Issue 45391.
+func TestQuote(t *testing.T) {
+	tests := []struct {
+		s, want string
+	}{
+		{`"`, `"\""`},
+		{`abc"xyz"`, `"abc\"xyz\""`},
+		{"", `""`},
+		{"abc", `"abc"`},
+		{`☺`, `"\xe2\x98\xba"`},
+		{`☺ hello ☺ hello`, `"\xe2\x98\xba hello \xe2\x98\xba hello"`},
+		{"\x04", `"\x04"`},
+	}
+	for _, tt := range tests {
+		if q := Quote(tt.s); q != tt.want {
+			t.Errorf("Quote(%q) = got %q, want %q", tt.s, q, tt.want)
+		}
+	}
+
+}
+
+// Issue 48037
+func TestFormatFractionalSecondSeparators(t *testing.T) {
+	tests := []struct {
+		s, want string
+	}{
+		{`15:04:05.000`, `21:00:57.012`},
+		{`15:04:05.999`, `21:00:57.012`},
+		{`15:04:05,000`, `21:00:57,012`},
+		{`15:04:05,999`, `21:00:57,012`},
+	}
+
+	// The numeric time represents Thu Feb  4 21:00:57.012345600 PST 2009
+	time := Unix(0, 1233810057012345600)
+	for _, tt := range tests {
+		if q := time.Format(tt.s); q != tt.want {
+			t.Errorf("Format(%q) = got %q, want %q", tt.s, q, tt.want)
+		}
+	}
+}
+
+var longFractionalDigitsTests = []struct {
+	value string
+	want  int
+}{
+	// 9 digits
+	{"2021-09-29T16:04:33.000000000Z", 0},
+	{"2021-09-29T16:04:33.000000001Z", 1},
+	{"2021-09-29T16:04:33.100000000Z", 100_000_000},
+	{"2021-09-29T16:04:33.100000001Z", 100_000_001},
+	{"2021-09-29T16:04:33.999999999Z", 999_999_999},
+	{"2021-09-29T16:04:33.012345678Z", 12_345_678},
+	// 10 digits, truncates
+	{"2021-09-29T16:04:33.0000000000Z", 0},
+	{"2021-09-29T16:04:33.0000000001Z", 0},
+	{"2021-09-29T16:04:33.1000000000Z", 100_000_000},
+	{"2021-09-29T16:04:33.1000000009Z", 100_000_000},
+	{"2021-09-29T16:04:33.9999999999Z", 999_999_999},
+	{"2021-09-29T16:04:33.0123456789Z", 12_345_678},
+	// 11 digits, truncates
+	{"2021-09-29T16:04:33.10000000000Z", 100_000_000},
+	{"2021-09-29T16:04:33.00123456789Z", 1_234_567},
+	// 12 digits, truncates
+	{"2021-09-29T16:04:33.000123456789Z", 123_456},
+	// 15 digits, truncates
+	{"2021-09-29T16:04:33.9999999999999999Z", 999_999_999},
+}
+
+// Issue 48685 and 54567.
+func TestParseFractionalSecondsLongerThanNineDigits(t *testing.T) {
+	for _, tt := range longFractionalDigitsTests {
+		for _, format := range []string{RFC3339, RFC3339Nano} {
+			tm, err := Parse(format, tt.value)
+			if err != nil {
+				t.Errorf("Parse(%q, %q) error: %v", format, tt.value, err)
+				continue
+			}
+			if got := tm.Nanosecond(); got != tt.want {
+				t.Errorf("Parse(%q, %q) = got %d, want %d", format, tt.value, got, tt.want)
+			}
+		}
+	}
+}
+
+func FuzzFormatRFC3339(f *testing.F) {
+	for _, ts := range [][2]int64{
+		{math.MinInt64, math.MinInt64}, // 292277026304-08-26T15:42:51Z
+		{-62167219200, 0},              // 0000-01-01T00:00:00Z
+		{1661201140, 676836973},        // 2022-08-22T20:45:40.676836973Z
+		{253402300799, 999999999},      // 9999-12-31T23:59:59.999999999Z
+		{math.MaxInt64, math.MaxInt64}, // -292277022365-05-08T08:17:07Z
+	} {
+		f.Add(ts[0], ts[1], true, false, 0)
+		f.Add(ts[0], ts[1], false, true, 0)
+		for _, offset := range []int{0, 60, 60 * 60, 99*60*60 + 99*60, 123456789} {
+			f.Add(ts[0], ts[1], false, false, -offset)
+			f.Add(ts[0], ts[1], false, false, +offset)
+		}
+	}
+
+	f.Fuzz(func(t *testing.T, sec, nsec int64, useUTC, useLocal bool, tzOffset int) {
+		var loc *Location
+		switch {
+		case useUTC:
+			loc = UTC
+		case useLocal:
+			loc = Local
+		default:
+			loc = FixedZone("", tzOffset)
+		}
+		ts := Unix(sec, nsec).In(loc)
+
+		got := AppendFormatRFC3339(ts, nil, false)
+		want := AppendFormatAny(ts, nil, RFC3339)
+		if !bytes.Equal(got, want) {
+			t.Errorf("Format(%s, RFC3339) mismatch:\n\tgot:  %s\n\twant: %s", ts, got, want)
+		}
+
+		gotNanos := AppendFormatRFC3339(ts, nil, true)
+		wantNanos := AppendFormatAny(ts, nil, RFC3339Nano)
+		if !bytes.Equal(got, want) {
+			t.Errorf("Format(%s, RFC3339Nano) mismatch:\n\tgot:  %s\n\twant: %s", ts, gotNanos, wantNanos)
+		}
+	})
+}
+
+func FuzzParseRFC3339(f *testing.F) {
+	for _, tt := range formatTests {
+		f.Add(tt.result)
+	}
+	for _, tt := range parseTests {
+		f.Add(tt.value)
+	}
+	for _, tt := range parseErrorTests {
+		f.Add(tt.value)
+	}
+	for _, tt := range longFractionalDigitsTests {
+		f.Add(tt.value)
+	}
+
+	f.Fuzz(func(t *testing.T, s string) {
+		// equalTime is like time.Time.Equal, but also compares the time zone.
+		equalTime := func(t1, t2 Time) bool {
+			name1, offset1 := t1.Zone()
+			name2, offset2 := t2.Zone()
+			return t1.Equal(t2) && name1 == name2 && offset1 == offset2
+		}
+
+		for _, tz := range []*Location{UTC, Local} {
+			// Parsing as RFC3339 or RFC3339Nano should be identical.
+			t1, err1 := ParseAny(RFC3339, s, UTC, tz)
+			t2, err2 := ParseAny(RFC3339Nano, s, UTC, tz)
+			switch {
+			case (err1 == nil) != (err2 == nil):
+				t.Fatalf("ParseAny(%q) error mismatch:\n\tgot:  %v\n\twant: %v", s, err1, err2)
+			case !equalTime(t1, t2):
+				t.Fatalf("ParseAny(%q) value mismatch:\n\tgot:  %v\n\twant: %v", s, t1, t2)
+			}
+
+			// TODO(https://go.dev/issue/54580):
+			// Remove these checks after ParseAny rejects all invalid RFC 3339.
+			if err1 == nil {
+				num2 := func(s string) byte { return 10*(s[0]-'0') + (s[1] - '0') }
+				switch {
+				case len(s) > 12 && s[12] == ':':
+					t.Skipf("ParseAny(%q) incorrectly allows single-digit hour fields", s)
+				case len(s) > 19 && s[19] == ',':
+					t.Skipf("ParseAny(%q) incorrectly allows comma as sub-second separator", s)
+				case !strings.HasSuffix(s, "Z") && len(s) > 4 && (num2(s[len(s)-5:]) >= 24 || num2(s[len(s)-2:]) >= 60):
+					t.Skipf("ParseAny(%q) incorrectly allows out-of-range zone offset", s)
+				}
+			}
+
+			// Customized parser should be identical to general parser.
+			switch got, ok := ParseRFC3339(s, tz); {
+			case ok != (err1 == nil):
+				t.Fatalf("ParseRFC3339(%q) error mismatch:\n\tgot:  %v\n\twant: %v", s, ok, err1 == nil)
+			case !equalTime(got, t1):
+				t.Fatalf("ParseRFC3339(%q) value mismatch:\n\tgot:  %v\n\twant: %v", s, got, t2)
+			}
+		}
+	})
+}
diff --git a/src/time/genzabbrs.go b/src/time/genzabbrs.go
new file mode 100644
index 0000000..7dbd22f
--- /dev/null
+++ b/src/time/genzabbrs.go
@@ -0,0 +1,156 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+
+//
+// usage:
+//
+// go run genzabbrs.go -output zoneinfo_abbrs_windows.go
+//
+
+package main
+
+import (
+	"bytes"
+	"encoding/xml"
+	"flag"
+	"go/format"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"sort"
+	"text/template"
+	"time"
+)
+
+var filename = flag.String("output", "zoneinfo_abbrs_windows.go", "output file name")
+
+// getAbbrs finds timezone abbreviations (standard and daylight saving time)
+// for location l.
+func getAbbrs(l *time.Location) (st, dt string) {
+	t := time.Date(time.Now().Year(), 0, 1, 0, 0, 0, 0, l)
+	abbr1, off1 := t.Zone()
+	for i := 0; i < 12; i++ {
+		t = t.AddDate(0, 1, 0)
+		abbr2, off2 := t.Zone()
+		if abbr1 != abbr2 {
+			if off2-off1 < 0 { // southern hemisphere
+				abbr1, abbr2 = abbr2, abbr1
+			}
+			return abbr1, abbr2
+		}
+	}
+	return abbr1, abbr1
+}
+
+type zone struct {
+	WinName  string
+	UnixName string
+	StTime   string
+	DSTime   string
+}
+
+const wzURL = "https://raw.githubusercontent.com/unicode-org/cldr/main/common/supplemental/windowsZones.xml"
+
+type MapZone struct {
+	Other     string `xml:"other,attr"`
+	Territory string `xml:"territory,attr"`
+	Type      string `xml:"type,attr"`
+}
+
+type SupplementalData struct {
+	Zones []MapZone `xml:"windowsZones>mapTimezones>mapZone"`
+}
+
+func readWindowsZones() ([]*zone, error) {
+	r, err := http.Get(wzURL)
+	if err != nil {
+		return nil, err
+	}
+	defer r.Body.Close()
+
+	data, err := io.ReadAll(r.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var sd SupplementalData
+	err = xml.Unmarshal(data, &sd)
+	if err != nil {
+		return nil, err
+	}
+	zs := make([]*zone, 0)
+	for _, z := range sd.Zones {
+		if z.Territory != "001" {
+			// to avoid dups. I don't know why.
+			continue
+		}
+		l, err := time.LoadLocation(z.Type)
+		if err != nil {
+			return nil, err
+		}
+		st, dt := getAbbrs(l)
+		zs = append(zs, &zone{
+			WinName:  z.Other,
+			UnixName: z.Type,
+			StTime:   st,
+			DSTime:   dt,
+		})
+	}
+	return zs, nil
+}
+
+func main() {
+	flag.Parse()
+	zs, err := readWindowsZones()
+	if err != nil {
+		log.Fatal(err)
+	}
+	sort.Slice(zs, func(i, j int) bool {
+		return zs[i].UnixName < zs[j].UnixName
+	})
+	var v = struct {
+		URL string
+		Zs  []*zone
+	}{
+		wzURL,
+		zs,
+	}
+	var buf bytes.Buffer
+	err = template.Must(template.New("prog").Parse(prog)).Execute(&buf, v)
+	if err != nil {
+		log.Fatal(err)
+	}
+	data, err := format.Source(buf.Bytes())
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = os.WriteFile(*filename, data, 0644)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+const prog = `
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by genzabbrs.go; DO NOT EDIT.
+// Based on information from {{.URL}}
+
+package time
+
+type abbr struct {
+	std string
+	dst string
+}
+
+var abbrs = map[string]abbr{
+{{range .Zs}}	"{{.WinName}}": {"{{.StTime}}", "{{.DSTime}}"}, // {{.UnixName}}
+{{end}}}
+
+`
diff --git a/src/time/internal_test.go b/src/time/internal_test.go
new file mode 100644
index 0000000..4c4a720
--- /dev/null
+++ b/src/time/internal_test.go
@@ -0,0 +1,72 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+func init() {
+	// Force US/Pacific for time zone tests.
+	ForceUSPacificForTesting()
+}
+
+func initTestingZone() {
+	// For hermeticity, use only tzinfo source from the test's GOROOT,
+	// not the system sources and not whatever GOROOT may happen to be
+	// set in the process's environment (if any).
+	// This test runs in GOROOT/src/time, so GOROOT is "../..",
+	// but it is theoretically possible
+	sources := []string{"../../lib/time/zoneinfo.zip"}
+	z, err := loadLocation("America/Los_Angeles", sources)
+	if err != nil {
+		panic("cannot load America/Los_Angeles for testing: " + err.Error() + "; you may want to use -tags=timetzdata")
+	}
+	z.name = "Local"
+	localLoc = *z
+}
+
+var origPlatformZoneSources []string = platformZoneSources
+
+func disablePlatformSources() (undo func()) {
+	platformZoneSources = nil
+	return func() {
+		platformZoneSources = origPlatformZoneSources
+	}
+}
+
+var Interrupt = interrupt
+var DaysIn = daysIn
+
+func empty(arg any, seq uintptr) {}
+
+// Test that a runtimeTimer with a period that would overflow when on
+// expiration does not throw or cause other timers to hang.
+//
+// This test has to be in internal_test.go since it fiddles with
+// unexported data structures.
+func CheckRuntimeTimerPeriodOverflow() {
+	// We manually create a runtimeTimer with huge period, but that expires
+	// immediately. The public Timer interface would require waiting for
+	// the entire period before the first update.
+	r := &runtimeTimer{
+		when:   runtimeNano(),
+		period: 1<<63 - 1,
+		f:      empty,
+		arg:    nil,
+	}
+	startTimer(r)
+	defer stopTimer(r)
+
+	// If this test fails, we will either throw (when siftdownTimer detects
+	// bad when on update), or other timers will hang (if the timer in a
+	// heap is in a bad state). There is no reliable way to test this, but
+	// we wait on a short timer here as a smoke test (alternatively, timers
+	// in later tests may hang).
+	<-After(25 * Millisecond)
+}
+
+var (
+	MinMonoTime = Time{wall: 1 << 63, ext: -1 << 63, loc: UTC}
+	MaxMonoTime = Time{wall: 1 << 63, ext: 1<<63 - 1, loc: UTC}
+
+	NotMonoNegativeTime = Time{wall: 0, ext: -1<<63 + 50}
+)
diff --git a/src/time/mono_test.go b/src/time/mono_test.go
new file mode 100644
index 0000000..cdbb11e
--- /dev/null
+++ b/src/time/mono_test.go
@@ -0,0 +1,278 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"strings"
+	"testing"
+	. "time"
+)
+
+func TestHasMonotonicClock(t *testing.T) {
+	yes := func(expr string, tt Time) {
+		if GetMono(&tt) == 0 {
+			t.Errorf("%s: missing monotonic clock reading", expr)
+		}
+	}
+	no := func(expr string, tt Time) {
+		if GetMono(&tt) != 0 {
+			t.Errorf("%s: unexpected monotonic clock reading", expr)
+		}
+	}
+
+	yes("<-After(1)", <-After(1))
+	ticker := NewTicker(1)
+	yes("<-Tick(1)", <-ticker.C)
+	ticker.Stop()
+	no("Date(2009, 11, 23, 0, 0, 0, 0, UTC)", Date(2009, 11, 23, 0, 0, 0, 0, UTC))
+	tp, _ := Parse(UnixDate, "Sat Mar  7 11:06:39 PST 2015")
+	no(`Parse(UnixDate, "Sat Mar  7 11:06:39 PST 2015")`, tp)
+	no("Unix(1486057371, 0)", Unix(1486057371, 0))
+
+	yes("Now()", Now())
+
+	tu := Unix(1486057371, 0)
+	tm := tu
+	SetMono(&tm, 123456)
+	no("tu", tu)
+	yes("tm", tm)
+
+	no("tu.Add(1)", tu.Add(1))
+	no("tu.In(UTC)", tu.In(UTC))
+	no("tu.AddDate(1, 1, 1)", tu.AddDate(1, 1, 1))
+	no("tu.AddDate(0, 0, 0)", tu.AddDate(0, 0, 0))
+	no("tu.Local()", tu.Local())
+	no("tu.UTC()", tu.UTC())
+	no("tu.Round(2)", tu.Round(2))
+	no("tu.Truncate(2)", tu.Truncate(2))
+
+	yes("tm.Add(1)", tm.Add(1))
+	no("tm.AddDate(1, 1, 1)", tm.AddDate(1, 1, 1))
+	no("tm.AddDate(0, 0, 0)", tm.AddDate(0, 0, 0))
+	no("tm.In(UTC)", tm.In(UTC))
+	no("tm.Local()", tm.Local())
+	no("tm.UTC()", tm.UTC())
+	no("tm.Round(2)", tm.Round(2))
+	no("tm.Truncate(2)", tm.Truncate(2))
+}
+
+func TestMonotonicAdd(t *testing.T) {
+	tm := Unix(1486057371, 123456)
+	SetMono(&tm, 123456789012345)
+
+	t2 := tm.Add(1e8)
+	if t2.Nanosecond() != 100123456 {
+		t.Errorf("t2.Nanosecond() = %d, want 100123456", t2.Nanosecond())
+	}
+	if GetMono(&t2) != 123456889012345 {
+		t.Errorf("t2.mono = %d, want 123456889012345", GetMono(&t2))
+	}
+
+	t3 := tm.Add(-9e18) // wall now out of range
+	if t3.Nanosecond() != 123456 {
+		t.Errorf("t3.Nanosecond() = %d, want 123456", t3.Nanosecond())
+	}
+	if GetMono(&t3) != 0 {
+		t.Errorf("t3.mono = %d, want 0 (wall time out of range for monotonic reading)", GetMono(&t3))
+	}
+
+	t4 := tm.Add(+9e18) // wall now out of range
+	if t4.Nanosecond() != 123456 {
+		t.Errorf("t4.Nanosecond() = %d, want 123456", t4.Nanosecond())
+	}
+	if GetMono(&t4) != 0 {
+		t.Errorf("t4.mono = %d, want 0 (wall time out of range for monotonic reading)", GetMono(&t4))
+	}
+
+	tn := Now()
+	tn1 := tn.Add(1 * Hour)
+	Sleep(100 * Millisecond)
+	d := Until(tn1)
+	if d < 59*Minute {
+		t.Errorf("Until(Now().Add(1*Hour)) = %v, wanted at least 59m", d)
+	}
+	now := Now()
+	if now.After(tn1) {
+		t.Errorf("Now().After(Now().Add(1*Hour)) = true, want false")
+	}
+	if !tn1.After(now) {
+		t.Errorf("Now().Add(1*Hour).After(now) = false, want true")
+	}
+	if tn1.Before(now) {
+		t.Errorf("Now().Add(1*Hour).Before(Now()) = true, want false")
+	}
+	if !now.Before(tn1) {
+		t.Errorf("Now().Before(Now().Add(1*Hour)) = false, want true")
+	}
+	if got, want := now.Compare(tn1), -1; got != want {
+		t.Errorf("Now().Compare(Now().Add(1*Hour)) = %d, want %d", got, want)
+	}
+	if got, want := tn1.Compare(now), 1; got != want {
+		t.Errorf("Now().Add(1*Hour).Compare(Now()) = %d, want %d", got, want)
+	}
+}
+
+func TestMonotonicSub(t *testing.T) {
+	t1 := Unix(1483228799, 995e6)
+	SetMono(&t1, 123456789012345)
+
+	t2 := Unix(1483228799, 5e6)
+	SetMono(&t2, 123456789012345+10e6)
+
+	t3 := Unix(1483228799, 995e6)
+	SetMono(&t3, 123456789012345+1e9)
+
+	t1w := t1.AddDate(0, 0, 0)
+	if GetMono(&t1w) != 0 {
+		t.Fatalf("AddDate didn't strip monotonic clock reading")
+	}
+	t2w := t2.AddDate(0, 0, 0)
+	if GetMono(&t2w) != 0 {
+		t.Fatalf("AddDate didn't strip monotonic clock reading")
+	}
+	t3w := t3.AddDate(0, 0, 0)
+	if GetMono(&t3w) != 0 {
+		t.Fatalf("AddDate didn't strip monotonic clock reading")
+	}
+
+	sub := func(txs, tys string, tx, txw, ty, tyw Time, d, dw Duration) {
+		check := func(expr string, d, want Duration) {
+			if d != want {
+				t.Errorf("%s = %v, want %v", expr, d, want)
+			}
+		}
+		check(txs+".Sub("+tys+")", tx.Sub(ty), d)
+		check(txs+"w.Sub("+tys+")", txw.Sub(ty), dw)
+		check(txs+".Sub("+tys+"w)", tx.Sub(tyw), dw)
+		check(txs+"w.Sub("+tys+"w)", txw.Sub(tyw), dw)
+	}
+	sub("t1", "t1", t1, t1w, t1, t1w, 0, 0)
+	sub("t1", "t2", t1, t1w, t2, t2w, -10*Millisecond, 990*Millisecond)
+	sub("t1", "t3", t1, t1w, t3, t3w, -1000*Millisecond, 0)
+
+	sub("t2", "t1", t2, t2w, t1, t1w, 10*Millisecond, -990*Millisecond)
+	sub("t2", "t2", t2, t2w, t2, t2w, 0, 0)
+	sub("t2", "t3", t2, t2w, t3, t3w, -990*Millisecond, -990*Millisecond)
+
+	sub("t3", "t1", t3, t3w, t1, t1w, 1000*Millisecond, 0)
+	sub("t3", "t2", t3, t3w, t2, t2w, 990*Millisecond, 990*Millisecond)
+	sub("t3", "t3", t3, t3w, t3, t3w, 0, 0)
+
+	cmp := func(txs, tys string, tx, txw, ty, tyw Time, c, cw int) {
+		check := func(expr string, b, want any) {
+			if b != want {
+				t.Errorf("%s = %v, want %v", expr, b, want)
+			}
+		}
+		check(txs+".After("+tys+")", tx.After(ty), c > 0)
+		check(txs+"w.After("+tys+")", txw.After(ty), cw > 0)
+		check(txs+".After("+tys+"w)", tx.After(tyw), cw > 0)
+		check(txs+"w.After("+tys+"w)", txw.After(tyw), cw > 0)
+
+		check(txs+".Before("+tys+")", tx.Before(ty), c < 0)
+		check(txs+"w.Before("+tys+")", txw.Before(ty), cw < 0)
+		check(txs+".Before("+tys+"w)", tx.Before(tyw), cw < 0)
+		check(txs+"w.Before("+tys+"w)", txw.Before(tyw), cw < 0)
+
+		check(txs+".Equal("+tys+")", tx.Equal(ty), c == 0)
+		check(txs+"w.Equal("+tys+")", txw.Equal(ty), cw == 0)
+		check(txs+".Equal("+tys+"w)", tx.Equal(tyw), cw == 0)
+		check(txs+"w.Equal("+tys+"w)", txw.Equal(tyw), cw == 0)
+
+		check(txs+".Compare("+tys+")", tx.Compare(ty), c)
+		check(txs+"w.Compare("+tys+")", txw.Compare(ty), cw)
+		check(txs+".Compare("+tys+"w)", tx.Compare(tyw), cw)
+		check(txs+"w.Compare("+tys+"w)", txw.Compare(tyw), cw)
+	}
+
+	cmp("t1", "t1", t1, t1w, t1, t1w, 0, 0)
+	cmp("t1", "t2", t1, t1w, t2, t2w, -1, +1)
+	cmp("t1", "t3", t1, t1w, t3, t3w, -1, 0)
+
+	cmp("t2", "t1", t2, t2w, t1, t1w, +1, -1)
+	cmp("t2", "t2", t2, t2w, t2, t2w, 0, 0)
+	cmp("t2", "t3", t2, t2w, t3, t3w, -1, -1)
+
+	cmp("t3", "t1", t3, t3w, t1, t1w, +1, 0)
+	cmp("t3", "t2", t3, t3w, t2, t2w, +1, +1)
+	cmp("t3", "t3", t3, t3w, t3, t3w, 0, 0)
+}
+
+func TestMonotonicOverflow(t *testing.T) {
+	t1 := Now().Add(-30 * Second)
+	d := Until(t1)
+	if d < -35*Second || -30*Second < d {
+		t.Errorf("Until(Now().Add(-30s)) = %v, want roughly -30s (-35s to -30s)", d)
+	}
+
+	t1 = Now().Add(30 * Second)
+	d = Until(t1)
+	if d < 25*Second || 30*Second < d {
+		t.Errorf("Until(Now().Add(-30s)) = %v, want roughly 30s (25s to 30s)", d)
+	}
+
+	t0 := Now()
+	t1 = t0.Add(Duration(1<<63 - 1))
+	if GetMono(&t1) != 0 {
+		t.Errorf("Now().Add(maxDuration) has monotonic clock reading (%v => %v %d %d)", t0.String(), t1.String(), t0.Unix(), t1.Unix())
+	}
+	t2 := t1.Add(-Duration(1<<63 - 1))
+	d = Since(t2)
+	if d < -10*Second || 10*Second < d {
+		t.Errorf("Since(Now().Add(max).Add(-max)) = %v, want [-10s, 10s]", d)
+	}
+
+	t0 = Now()
+	t1 = t0.Add(1 * Hour)
+	Sleep(100 * Millisecond)
+	t2 = Now().Add(-5 * Second)
+	if !t1.After(t2) {
+		t.Errorf("Now().Add(1*Hour).After(Now().Add(-5*Second)) = false, want true\nt1=%v\nt2=%v", t1, t2)
+	}
+	if t2.After(t1) {
+		t.Errorf("Now().Add(-5*Second).After(Now().Add(1*Hour)) = true, want false\nt1=%v\nt2=%v", t1, t2)
+	}
+	if t1.Before(t2) {
+		t.Errorf("Now().Add(1*Hour).Before(Now().Add(-5*Second)) = true, want false\nt1=%v\nt2=%v", t1, t2)
+	}
+	if !t2.Before(t1) {
+		t.Errorf("Now().Add(-5*Second).Before(Now().Add(1*Hour)) = false, want true\nt1=%v\nt2=%v", t1, t2)
+	}
+	if got, want := t1.Compare(t2), 1; got != want {
+		t.Errorf("Now().Add(1*Hour).Compare(Now().Add(-5*Second)) = %d, want %d\nt1=%v\nt2=%v", got, want, t1, t2)
+	}
+	if got, want := t2.Compare(t1), -1; got != want {
+		t.Errorf("Now().Add(-5*Second).Before(Now().Add(1*Hour)) = %d, want %d\nt1=%v\nt2=%v", got, want, t1, t2)
+	}
+}
+
+var monotonicStringTests = []struct {
+	mono int64
+	want string
+}{
+	{0, "m=+0.000000000"},
+	{123456789, "m=+0.123456789"},
+	{-123456789, "m=-0.123456789"},
+	{123456789000, "m=+123.456789000"},
+	{-123456789000, "m=-123.456789000"},
+	{9e18, "m=+9000000000.000000000"},
+	{-9e18, "m=-9000000000.000000000"},
+	{-1 << 63, "m=-9223372036.854775808"},
+}
+
+func TestMonotonicString(t *testing.T) {
+	t1 := Now()
+	t.Logf("Now() = %v", t1)
+
+	for _, tt := range monotonicStringTests {
+		t1 := Now()
+		SetMono(&t1, tt.mono)
+		s := t1.String()
+		got := s[strings.LastIndex(s, " ")+1:]
+		if got != tt.want {
+			t.Errorf("with mono=%d: got %q; want %q", tt.mono, got, tt.want)
+		}
+	}
+}
diff --git a/src/time/sleep.go b/src/time/sleep.go
new file mode 100644
index 0000000..cdab478
--- /dev/null
+++ b/src/time/sleep.go
@@ -0,0 +1,177 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+// Sleep pauses the current goroutine for at least the duration d.
+// A negative or zero duration causes Sleep to return immediately.
+func Sleep(d Duration)
+
+// Interface to timers implemented in package runtime.
+// Must be in sync with ../runtime/time.go:/^type timer
+type runtimeTimer struct {
+	pp       uintptr
+	when     int64
+	period   int64
+	f        func(any, uintptr) // NOTE: must not be closure
+	arg      any
+	seq      uintptr
+	nextwhen int64
+	status   uint32
+}
+
+// when is a helper function for setting the 'when' field of a runtimeTimer.
+// It returns what the time will be, in nanoseconds, Duration d in the future.
+// If d is negative, it is ignored. If the returned value would be less than
+// zero because of an overflow, MaxInt64 is returned.
+func when(d Duration) int64 {
+	if d <= 0 {
+		return runtimeNano()
+	}
+	t := runtimeNano() + int64(d)
+	if t < 0 {
+		// N.B. runtimeNano() and d are always positive, so addition
+		// (including overflow) will never result in t == 0.
+		t = 1<<63 - 1 // math.MaxInt64
+	}
+	return t
+}
+
+func startTimer(*runtimeTimer)
+func stopTimer(*runtimeTimer) bool
+func resetTimer(*runtimeTimer, int64) bool
+func modTimer(t *runtimeTimer, when, period int64, f func(any, uintptr), arg any, seq uintptr)
+
+// The Timer type represents a single event.
+// When the Timer expires, the current time will be sent on C,
+// unless the Timer was created by AfterFunc.
+// A Timer must be created with NewTimer or AfterFunc.
+type Timer struct {
+	C <-chan Time
+	r runtimeTimer
+}
+
+// Stop prevents the Timer from firing.
+// It returns true if the call stops the timer, false if the timer has already
+// expired or been stopped.
+// Stop does not close the channel, to prevent a read from the channel succeeding
+// incorrectly.
+//
+// To ensure the channel is empty after a call to Stop, check the
+// return value and drain the channel.
+// For example, assuming the program has not received from t.C already:
+//
+//	if !t.Stop() {
+//		<-t.C
+//	}
+//
+// This cannot be done concurrent to other receives from the Timer's
+// channel or other calls to the Timer's Stop method.
+//
+// For a timer created with AfterFunc(d, f), if t.Stop returns false, then the timer
+// has already expired and the function f has been started in its own goroutine;
+// Stop does not wait for f to complete before returning.
+// If the caller needs to know whether f is completed, it must coordinate
+// with f explicitly.
+func (t *Timer) Stop() bool {
+	if t.r.f == nil {
+		panic("time: Stop called on uninitialized Timer")
+	}
+	return stopTimer(&t.r)
+}
+
+// NewTimer creates a new Timer that will send
+// the current time on its channel after at least duration d.
+func NewTimer(d Duration) *Timer {
+	c := make(chan Time, 1)
+	t := &Timer{
+		C: c,
+		r: runtimeTimer{
+			when: when(d),
+			f:    sendTime,
+			arg:  c,
+		},
+	}
+	startTimer(&t.r)
+	return t
+}
+
+// Reset changes the timer to expire after duration d.
+// It returns true if the timer had been active, false if the timer had
+// expired or been stopped.
+//
+// For a Timer created with NewTimer, Reset should be invoked only on
+// stopped or expired timers with drained channels.
+//
+// If a program has already received a value from t.C, the timer is known
+// to have expired and the channel drained, so t.Reset can be used directly.
+// If a program has not yet received a value from t.C, however,
+// the timer must be stopped and—if Stop reports that the timer expired
+// before being stopped—the channel explicitly drained:
+//
+//	if !t.Stop() {
+//		<-t.C
+//	}
+//	t.Reset(d)
+//
+// This should not be done concurrent to other receives from the Timer's
+// channel.
+//
+// Note that it is not possible to use Reset's return value correctly, as there
+// is a race condition between draining the channel and the new timer expiring.
+// Reset should always be invoked on stopped or expired channels, as described above.
+// The return value exists to preserve compatibility with existing programs.
+//
+// For a Timer created with AfterFunc(d, f), Reset either reschedules
+// when f will run, in which case Reset returns true, or schedules f
+// to run again, in which case it returns false.
+// When Reset returns false, Reset neither waits for the prior f to
+// complete before returning nor does it guarantee that the subsequent
+// goroutine running f does not run concurrently with the prior
+// one. If the caller needs to know whether the prior execution of
+// f is completed, it must coordinate with f explicitly.
+func (t *Timer) Reset(d Duration) bool {
+	if t.r.f == nil {
+		panic("time: Reset called on uninitialized Timer")
+	}
+	w := when(d)
+	return resetTimer(&t.r, w)
+}
+
+// sendTime does a non-blocking send of the current time on c.
+func sendTime(c any, seq uintptr) {
+	select {
+	case c.(chan Time) <- Now():
+	default:
+	}
+}
+
+// After waits for the duration to elapse and then sends the current time
+// on the returned channel.
+// It is equivalent to NewTimer(d).C.
+// The underlying Timer is not recovered by the garbage collector
+// until the timer fires. If efficiency is a concern, use NewTimer
+// instead and call Timer.Stop if the timer is no longer needed.
+func After(d Duration) <-chan Time {
+	return NewTimer(d).C
+}
+
+// AfterFunc waits for the duration to elapse and then calls f
+// in its own goroutine. It returns a Timer that can
+// be used to cancel the call using its Stop method.
+func AfterFunc(d Duration, f func()) *Timer {
+	t := &Timer{
+		r: runtimeTimer{
+			when: when(d),
+			f:    goFunc,
+			arg:  f,
+		},
+	}
+	startTimer(&t.r)
+	return t
+}
+
+func goFunc(arg any, seq uintptr) {
+	go arg.(func())()
+}
diff --git a/src/time/sleep_test.go b/src/time/sleep_test.go
new file mode 100644
index 0000000..2f79124
--- /dev/null
+++ b/src/time/sleep_test.go
@@ -0,0 +1,821 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"errors"
+	"fmt"
+	"internal/testenv"
+	"math/rand"
+	"runtime"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"testing"
+	. "time"
+)
+
+// Go runtime uses different Windows timers for time.Now and sleeping.
+// These can tick at different frequencies and can arrive out of sync.
+// The effect can be seen, for example, as time.Sleep(100ms) is actually
+// shorter then 100ms when measured as difference between time.Now before and
+// after time.Sleep call. This was observed on Windows XP SP3 (windows/386).
+// windowsInaccuracy is to ignore such errors.
+const windowsInaccuracy = 17 * Millisecond
+
+func TestSleep(t *testing.T) {
+	const delay = 100 * Millisecond
+	go func() {
+		Sleep(delay / 2)
+		Interrupt()
+	}()
+	start := Now()
+	Sleep(delay)
+	delayadj := delay
+	if runtime.GOOS == "windows" {
+		delayadj -= windowsInaccuracy
+	}
+	duration := Now().Sub(start)
+	if duration < delayadj {
+		t.Fatalf("Sleep(%s) slept for only %s", delay, duration)
+	}
+}
+
+// Test the basic function calling behavior. Correct queueing
+// behavior is tested elsewhere, since After and AfterFunc share
+// the same code.
+func TestAfterFunc(t *testing.T) {
+	i := 10
+	c := make(chan bool)
+	var f func()
+	f = func() {
+		i--
+		if i >= 0 {
+			AfterFunc(0, f)
+			Sleep(1 * Second)
+		} else {
+			c <- true
+		}
+	}
+
+	AfterFunc(0, f)
+	<-c
+}
+
+func TestAfterStress(t *testing.T) {
+	var stop atomic.Bool
+	go func() {
+		for !stop.Load() {
+			runtime.GC()
+			// Yield so that the OS can wake up the timer thread,
+			// so that it can generate channel sends for the main goroutine,
+			// which will eventually set stop = 1 for us.
+			Sleep(Nanosecond)
+		}
+	}()
+	ticker := NewTicker(1)
+	for i := 0; i < 100; i++ {
+		<-ticker.C
+	}
+	ticker.Stop()
+	stop.Store(true)
+}
+
+func benchmark(b *testing.B, bench func(n int)) {
+
+	// Create equal number of garbage timers on each P before starting
+	// the benchmark.
+	var wg sync.WaitGroup
+	garbageAll := make([][]*Timer, runtime.GOMAXPROCS(0))
+	for i := range garbageAll {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			garbage := make([]*Timer, 1<<15)
+			for j := range garbage {
+				garbage[j] = AfterFunc(Hour, nil)
+			}
+			garbageAll[i] = garbage
+		}(i)
+	}
+	wg.Wait()
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			bench(1000)
+		}
+	})
+	b.StopTimer()
+
+	for _, garbage := range garbageAll {
+		for _, t := range garbage {
+			t.Stop()
+		}
+	}
+}
+
+func BenchmarkAfterFunc(b *testing.B) {
+	benchmark(b, func(n int) {
+		c := make(chan bool)
+		var f func()
+		f = func() {
+			n--
+			if n >= 0 {
+				AfterFunc(0, f)
+			} else {
+				c <- true
+			}
+		}
+
+		AfterFunc(0, f)
+		<-c
+	})
+}
+
+func BenchmarkAfter(b *testing.B) {
+	benchmark(b, func(n int) {
+		for i := 0; i < n; i++ {
+			<-After(1)
+		}
+	})
+}
+
+func BenchmarkStop(b *testing.B) {
+	benchmark(b, func(n int) {
+		for i := 0; i < n; i++ {
+			NewTimer(1 * Second).Stop()
+		}
+	})
+}
+
+func BenchmarkSimultaneousAfterFunc(b *testing.B) {
+	benchmark(b, func(n int) {
+		var wg sync.WaitGroup
+		wg.Add(n)
+		for i := 0; i < n; i++ {
+			AfterFunc(0, wg.Done)
+		}
+		wg.Wait()
+	})
+}
+
+func BenchmarkStartStop(b *testing.B) {
+	benchmark(b, func(n int) {
+		timers := make([]*Timer, n)
+		for i := 0; i < n; i++ {
+			timers[i] = AfterFunc(Hour, nil)
+		}
+
+		for i := 0; i < n; i++ {
+			timers[i].Stop()
+		}
+	})
+}
+
+func BenchmarkReset(b *testing.B) {
+	benchmark(b, func(n int) {
+		t := NewTimer(Hour)
+		for i := 0; i < n; i++ {
+			t.Reset(Hour)
+		}
+		t.Stop()
+	})
+}
+
+func BenchmarkSleep(b *testing.B) {
+	benchmark(b, func(n int) {
+		var wg sync.WaitGroup
+		wg.Add(n)
+		for i := 0; i < n; i++ {
+			go func() {
+				Sleep(Nanosecond)
+				wg.Done()
+			}()
+		}
+		wg.Wait()
+	})
+}
+
+func TestAfter(t *testing.T) {
+	const delay = 100 * Millisecond
+	start := Now()
+	end := <-After(delay)
+	delayadj := delay
+	if runtime.GOOS == "windows" {
+		delayadj -= windowsInaccuracy
+	}
+	if duration := Now().Sub(start); duration < delayadj {
+		t.Fatalf("After(%s) slept for only %d ns", delay, duration)
+	}
+	if min := start.Add(delayadj); end.Before(min) {
+		t.Fatalf("After(%s) expect >= %s, got %s", delay, min, end)
+	}
+}
+
+func TestAfterTick(t *testing.T) {
+	const Count = 10
+	Delta := 100 * Millisecond
+	if testing.Short() {
+		Delta = 10 * Millisecond
+	}
+	t0 := Now()
+	for i := 0; i < Count; i++ {
+		<-After(Delta)
+	}
+	t1 := Now()
+	d := t1.Sub(t0)
+	target := Delta * Count
+	if d < target*9/10 {
+		t.Fatalf("%d ticks of %s too fast: took %s, expected %s", Count, Delta, d, target)
+	}
+	if !testing.Short() && d > target*30/10 {
+		t.Fatalf("%d ticks of %s too slow: took %s, expected %s", Count, Delta, d, target)
+	}
+}
+
+func TestAfterStop(t *testing.T) {
+	// We want to test that we stop a timer before it runs.
+	// We also want to test that it didn't run after a longer timer.
+	// Since we don't want the test to run for too long, we don't
+	// want to use lengthy times. That makes the test inherently flaky.
+	// So only report an error if it fails five times in a row.
+
+	var errs []string
+	logErrs := func() {
+		for _, e := range errs {
+			t.Log(e)
+		}
+	}
+
+	for i := 0; i < 5; i++ {
+		AfterFunc(100*Millisecond, func() {})
+		t0 := NewTimer(50 * Millisecond)
+		c1 := make(chan bool, 1)
+		t1 := AfterFunc(150*Millisecond, func() { c1 <- true })
+		c2 := After(200 * Millisecond)
+		if !t0.Stop() {
+			errs = append(errs, "failed to stop event 0")
+			continue
+		}
+		if !t1.Stop() {
+			errs = append(errs, "failed to stop event 1")
+			continue
+		}
+		<-c2
+		select {
+		case <-t0.C:
+			errs = append(errs, "event 0 was not stopped")
+			continue
+		case <-c1:
+			errs = append(errs, "event 1 was not stopped")
+			continue
+		default:
+		}
+		if t1.Stop() {
+			errs = append(errs, "Stop returned true twice")
+			continue
+		}
+
+		// Test passed, so all done.
+		if len(errs) > 0 {
+			t.Logf("saw %d errors, ignoring to avoid flakiness", len(errs))
+			logErrs()
+		}
+
+		return
+	}
+
+	t.Errorf("saw %d errors", len(errs))
+	logErrs()
+}
+
+func TestAfterQueuing(t *testing.T) {
+	// This test flakes out on some systems,
+	// so we'll try it a few times before declaring it a failure.
+	const attempts = 5
+	err := errors.New("!=nil")
+	for i := 0; i < attempts && err != nil; i++ {
+		delta := Duration(20+i*50) * Millisecond
+		if err = testAfterQueuing(delta); err != nil {
+			t.Logf("attempt %v failed: %v", i, err)
+		}
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+var slots = []int{5, 3, 6, 6, 6, 1, 1, 2, 7, 9, 4, 8, 0}
+
+type afterResult struct {
+	slot int
+	t    Time
+}
+
+func await(slot int, result chan<- afterResult, ac <-chan Time) {
+	result <- afterResult{slot, <-ac}
+}
+
+func testAfterQueuing(delta Duration) error {
+	// make the result channel buffered because we don't want
+	// to depend on channel queueing semantics that might
+	// possibly change in the future.
+	result := make(chan afterResult, len(slots))
+
+	t0 := Now()
+	for _, slot := range slots {
+		go await(slot, result, After(Duration(slot)*delta))
+	}
+	var order []int
+	var times []Time
+	for range slots {
+		r := <-result
+		order = append(order, r.slot)
+		times = append(times, r.t)
+	}
+	for i := range order {
+		if i > 0 && order[i] < order[i-1] {
+			return fmt.Errorf("After calls returned out of order: %v", order)
+		}
+	}
+	for i, t := range times {
+		dt := t.Sub(t0)
+		target := Duration(order[i]) * delta
+		if dt < target-delta/2 || dt > target+delta*10 {
+			return fmt.Errorf("After(%s) arrived at %s, expected [%s,%s]", target, dt, target-delta/2, target+delta*10)
+		}
+	}
+	return nil
+}
+
+func TestTimerStopStress(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+	for i := 0; i < 100; i++ {
+		go func(i int) {
+			timer := AfterFunc(2*Second, func() {
+				t.Errorf("timer %d was not stopped", i)
+			})
+			Sleep(1 * Second)
+			timer.Stop()
+		}(i)
+	}
+	Sleep(3 * Second)
+}
+
+func TestSleepZeroDeadlock(t *testing.T) {
+	// Sleep(0) used to hang, the sequence of events was as follows.
+	// Sleep(0) sets G's status to Gwaiting, but then immediately returns leaving the status.
+	// Then the goroutine calls e.g. new and falls down into the scheduler due to pending GC.
+	// After the GC nobody wakes up the goroutine from Gwaiting status.
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
+	c := make(chan bool)
+	go func() {
+		for i := 0; i < 100; i++ {
+			runtime.GC()
+		}
+		c <- true
+	}()
+	for i := 0; i < 100; i++ {
+		Sleep(0)
+		tmp := make(chan bool, 1)
+		tmp <- true
+		<-tmp
+	}
+	<-c
+}
+
+func testReset(d Duration) error {
+	t0 := NewTimer(2 * d)
+	Sleep(d)
+	if !t0.Reset(3 * d) {
+		return errors.New("resetting unfired timer returned false")
+	}
+	Sleep(2 * d)
+	select {
+	case <-t0.C:
+		return errors.New("timer fired early")
+	default:
+	}
+	Sleep(2 * d)
+	select {
+	case <-t0.C:
+	default:
+		return errors.New("reset timer did not fire")
+	}
+
+	if t0.Reset(50 * Millisecond) {
+		return errors.New("resetting expired timer returned true")
+	}
+	return nil
+}
+
+func TestReset(t *testing.T) {
+	// We try to run this test with increasingly larger multiples
+	// until one works so slow, loaded hardware isn't as flaky,
+	// but without slowing down fast machines unnecessarily.
+	//
+	// (maxDuration is several orders of magnitude longer than we
+	// expect this test to actually take on a fast, unloaded machine.)
+	d := 1 * Millisecond
+	const maxDuration = 10 * Second
+	for {
+		err := testReset(d)
+		if err == nil {
+			break
+		}
+		d *= 2
+		if d > maxDuration {
+			t.Error(err)
+		}
+		t.Logf("%v; trying duration %v", err, d)
+	}
+}
+
+// Test that sleeping (via Sleep or Timer) for an interval so large it
+// overflows does not result in a short sleep duration. Nor does it interfere
+// with execution of other timers. If it does, timers in this or subsequent
+// tests may not fire.
+func TestOverflowSleep(t *testing.T) {
+	const big = Duration(int64(1<<63 - 1))
+
+	go func() {
+		Sleep(big)
+		// On failure, this may return after the test has completed, so
+		// we need to panic instead.
+		panic("big sleep returned")
+	}()
+
+	select {
+	case <-After(big):
+		t.Fatalf("big timeout fired")
+	case <-After(25 * Millisecond):
+		// OK
+	}
+
+	const neg = Duration(-1 << 63)
+	Sleep(neg) // Returns immediately.
+	select {
+	case <-After(neg):
+		// OK
+	case <-After(1 * Second):
+		t.Fatalf("negative timeout didn't fire")
+	}
+}
+
+// Test that a panic while deleting a timer does not leave
+// the timers mutex held, deadlocking a ticker.Stop in a defer.
+func TestIssue5745(t *testing.T) {
+	ticker := NewTicker(Hour)
+	defer func() {
+		// would deadlock here before the fix due to
+		// lock taken before the segfault.
+		ticker.Stop()
+
+		if r := recover(); r == nil {
+			t.Error("Expected panic, but none happened.")
+		}
+	}()
+
+	// cause a panic due to a segfault
+	var timer *Timer
+	timer.Stop()
+	t.Error("Should be unreachable.")
+}
+
+func TestOverflowPeriodRuntimeTimer(t *testing.T) {
+	// This may hang forever if timers are broken. See comment near
+	// the end of CheckRuntimeTimerOverflow in internal_test.go.
+	CheckRuntimeTimerPeriodOverflow()
+}
+
+func checkZeroPanicString(t *testing.T) {
+	e := recover()
+	s, _ := e.(string)
+	if want := "called on uninitialized Timer"; !strings.Contains(s, want) {
+		t.Errorf("panic = %v; want substring %q", e, want)
+	}
+}
+
+func TestZeroTimerResetPanics(t *testing.T) {
+	defer checkZeroPanicString(t)
+	var tr Timer
+	tr.Reset(1)
+}
+
+func TestZeroTimerStopPanics(t *testing.T) {
+	defer checkZeroPanicString(t)
+	var tr Timer
+	tr.Stop()
+}
+
+// Test that zero duration timers aren't missed by the scheduler. Regression test for issue 44868.
+func TestZeroTimer(t *testing.T) {
+	if testing.Short() {
+		t.Skip("-short")
+	}
+
+	for i := 0; i < 1000000; i++ {
+		s := Now()
+		ti := NewTimer(0)
+		<-ti.C
+		if diff := Since(s); diff > 2*Second {
+			t.Errorf("Expected time to get value from Timer channel in less than 2 sec, took %v", diff)
+		}
+	}
+}
+
+// Test that rapidly moving a timer earlier doesn't cause it to get dropped.
+// Issue 47329.
+func TestTimerModifiedEarlier(t *testing.T) {
+	if runtime.GOOS == "plan9" && runtime.GOARCH == "arm" {
+		testenv.SkipFlaky(t, 50470)
+	}
+
+	past := Until(Unix(0, 0))
+	count := 1000
+	fail := 0
+	for i := 0; i < count; i++ {
+		timer := NewTimer(Hour)
+		for j := 0; j < 10; j++ {
+			if !timer.Stop() {
+				<-timer.C
+			}
+			timer.Reset(past)
+		}
+
+		deadline := NewTimer(10 * Second)
+		defer deadline.Stop()
+		now := Now()
+		select {
+		case <-timer.C:
+			if since := Since(now); since > 8*Second {
+				t.Errorf("timer took too long (%v)", since)
+				fail++
+			}
+		case <-deadline.C:
+			t.Error("deadline expired")
+		}
+	}
+
+	if fail > 0 {
+		t.Errorf("%d failures", fail)
+	}
+}
+
+// Test that rapidly moving timers earlier and later doesn't cause
+// some of the sleep times to be lost.
+// Issue 47762
+func TestAdjustTimers(t *testing.T) {
+	var rnd = rand.New(rand.NewSource(Now().UnixNano()))
+
+	timers := make([]*Timer, 100)
+	states := make([]int, len(timers))
+	indices := rnd.Perm(len(timers))
+
+	for len(indices) != 0 {
+		var ii = rnd.Intn(len(indices))
+		var i = indices[ii]
+
+		var timer = timers[i]
+		var state = states[i]
+		states[i]++
+
+		switch state {
+		case 0:
+			timers[i] = NewTimer(0)
+		case 1:
+			<-timer.C // Timer is now idle.
+
+		// Reset to various long durations, which we'll cancel.
+		case 2:
+			if timer.Reset(1 * Minute) {
+				panic("shouldn't be active (1)")
+			}
+		case 4:
+			if timer.Reset(3 * Minute) {
+				panic("shouldn't be active (3)")
+			}
+		case 6:
+			if timer.Reset(2 * Minute) {
+				panic("shouldn't be active (2)")
+			}
+
+		// Stop and drain a long-duration timer.
+		case 3, 5, 7:
+			if !timer.Stop() {
+				t.Logf("timer %d state %d Stop returned false", i, state)
+				<-timer.C
+			}
+
+		// Start a short-duration timer we expect to select without blocking.
+		case 8:
+			if timer.Reset(0) {
+				t.Fatal("timer.Reset returned true")
+			}
+		case 9:
+			now := Now()
+			<-timer.C
+			dur := Since(now)
+			if dur > 750*Millisecond {
+				t.Errorf("timer %d took %v to complete", i, dur)
+			}
+
+		// Timer is done. Swap with tail and remove.
+		case 10:
+			indices[ii] = indices[len(indices)-1]
+			indices = indices[:len(indices)-1]
+		}
+	}
+}
+
+// Benchmark timer latency when the thread that creates the timer is busy with
+// other work and the timers must be serviced by other threads.
+// https://golang.org/issue/38860
+func BenchmarkParallelTimerLatency(b *testing.B) {
+	gmp := runtime.GOMAXPROCS(0)
+	if gmp < 2 || runtime.NumCPU() < gmp {
+		b.Skip("skipping with GOMAXPROCS < 2 or NumCPU < GOMAXPROCS")
+	}
+
+	// allocate memory now to avoid GC interference later.
+	timerCount := gmp - 1
+	stats := make([]struct {
+		sum   float64
+		max   Duration
+		count int64
+		_     [5]int64 // cache line padding
+	}, timerCount)
+
+	// Ensure the time to start new threads to service timers will not pollute
+	// the results.
+	warmupScheduler(gmp)
+
+	// Note that other than the AfterFunc calls this benchmark is measuring it
+	// avoids using any other timers. In particular, the main goroutine uses
+	// doWork to spin for some durations because up through Go 1.15 if all
+	// threads are idle sysmon could leave deep sleep when we wake.
+
+	// Ensure sysmon is in deep sleep.
+	doWork(30 * Millisecond)
+
+	b.ResetTimer()
+
+	const delay = Millisecond
+	var wg sync.WaitGroup
+	var count int32
+	for i := 0; i < b.N; i++ {
+		wg.Add(timerCount)
+		atomic.StoreInt32(&count, 0)
+		for j := 0; j < timerCount; j++ {
+			j := j
+			expectedWakeup := Now().Add(delay)
+			AfterFunc(delay, func() {
+				late := Since(expectedWakeup)
+				if late < 0 {
+					late = 0
+				}
+				stats[j].count++
+				stats[j].sum += float64(late.Nanoseconds())
+				if late > stats[j].max {
+					stats[j].max = late
+				}
+				atomic.AddInt32(&count, 1)
+				for atomic.LoadInt32(&count) < int32(timerCount) {
+					// spin until all timers fired
+				}
+				wg.Done()
+			})
+		}
+
+		for atomic.LoadInt32(&count) < int32(timerCount) {
+			// spin until all timers fired
+		}
+		wg.Wait()
+
+		// Spin for a bit to let the other scheduler threads go idle before the
+		// next round.
+		doWork(Millisecond)
+	}
+	var total float64
+	var samples float64
+	max := Duration(0)
+	for _, s := range stats {
+		if s.max > max {
+			max = s.max
+		}
+		total += s.sum
+		samples += float64(s.count)
+	}
+	b.ReportMetric(0, "ns/op")
+	b.ReportMetric(total/samples, "avg-late-ns")
+	b.ReportMetric(float64(max.Nanoseconds()), "max-late-ns")
+}
+
+// Benchmark timer latency with staggered wakeup times and varying CPU bound
+// workloads. https://golang.org/issue/38860
+func BenchmarkStaggeredTickerLatency(b *testing.B) {
+	gmp := runtime.GOMAXPROCS(0)
+	if gmp < 2 || runtime.NumCPU() < gmp {
+		b.Skip("skipping with GOMAXPROCS < 2 or NumCPU < GOMAXPROCS")
+	}
+
+	const delay = 3 * Millisecond
+
+	for _, dur := range []Duration{300 * Microsecond, 2 * Millisecond} {
+		b.Run(fmt.Sprintf("work-dur=%s", dur), func(b *testing.B) {
+			for tickersPerP := 1; tickersPerP < int(delay/dur)+1; tickersPerP++ {
+				tickerCount := gmp * tickersPerP
+				b.Run(fmt.Sprintf("tickers-per-P=%d", tickersPerP), func(b *testing.B) {
+					// allocate memory now to avoid GC interference later.
+					stats := make([]struct {
+						sum   float64
+						max   Duration
+						count int64
+						_     [5]int64 // cache line padding
+					}, tickerCount)
+
+					// Ensure the time to start new threads to service timers
+					// will not pollute the results.
+					warmupScheduler(gmp)
+
+					b.ResetTimer()
+
+					var wg sync.WaitGroup
+					wg.Add(tickerCount)
+					for j := 0; j < tickerCount; j++ {
+						j := j
+						doWork(delay / Duration(gmp))
+						expectedWakeup := Now().Add(delay)
+						ticker := NewTicker(delay)
+						go func(c int, ticker *Ticker, firstWake Time) {
+							defer ticker.Stop()
+
+							for ; c > 0; c-- {
+								<-ticker.C
+								late := Since(expectedWakeup)
+								if late < 0 {
+									late = 0
+								}
+								stats[j].count++
+								stats[j].sum += float64(late.Nanoseconds())
+								if late > stats[j].max {
+									stats[j].max = late
+								}
+								expectedWakeup = expectedWakeup.Add(delay)
+								doWork(dur)
+							}
+							wg.Done()
+						}(b.N, ticker, expectedWakeup)
+					}
+					wg.Wait()
+
+					var total float64
+					var samples float64
+					max := Duration(0)
+					for _, s := range stats {
+						if s.max > max {
+							max = s.max
+						}
+						total += s.sum
+						samples += float64(s.count)
+					}
+					b.ReportMetric(0, "ns/op")
+					b.ReportMetric(total/samples, "avg-late-ns")
+					b.ReportMetric(float64(max.Nanoseconds()), "max-late-ns")
+				})
+			}
+		})
+	}
+}
+
+// warmupScheduler ensures the scheduler has at least targetThreadCount threads
+// in its thread pool.
+func warmupScheduler(targetThreadCount int) {
+	var wg sync.WaitGroup
+	var count int32
+	for i := 0; i < targetThreadCount; i++ {
+		wg.Add(1)
+		go func() {
+			atomic.AddInt32(&count, 1)
+			for atomic.LoadInt32(&count) < int32(targetThreadCount) {
+				// spin until all threads started
+			}
+
+			// spin a bit more to ensure they are all running on separate CPUs.
+			doWork(Millisecond)
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+}
+
+func doWork(dur Duration) {
+	start := Now()
+	for Since(start) < dur {
+	}
+}
diff --git a/src/time/sys_plan9.go b/src/time/sys_plan9.go
new file mode 100644
index 0000000..ba37cf5
--- /dev/null
+++ b/src/time/sys_plan9.go
@@ -0,0 +1,54 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build plan9
+
+package time
+
+import (
+	"errors"
+	"syscall"
+)
+
+// for testing: whatever interrupts a sleep
+func interrupt() {
+	// cannot predict pid, don't want to kill group
+}
+
+func open(name string) (uintptr, error) {
+	fd, err := syscall.Open(name, syscall.O_RDONLY)
+	if err != nil {
+		return 0, err
+	}
+	return uintptr(fd), nil
+}
+
+func read(fd uintptr, buf []byte) (int, error) {
+	return syscall.Read(int(fd), buf)
+}
+
+func closefd(fd uintptr) {
+	syscall.Close(int(fd))
+}
+
+func preadn(fd uintptr, buf []byte, off int) error {
+	whence := seekStart
+	if off < 0 {
+		whence = seekEnd
+	}
+	if _, err := syscall.Seek(int(fd), int64(off), whence); err != nil {
+		return err
+	}
+	for len(buf) > 0 {
+		m, err := syscall.Read(int(fd), buf)
+		if m <= 0 {
+			if err == nil {
+				return errors.New("short read")
+			}
+			return err
+		}
+		buf = buf[m:]
+	}
+	return nil
+}
diff --git a/src/time/sys_unix.go b/src/time/sys_unix.go
new file mode 100644
index 0000000..63634ac
--- /dev/null
+++ b/src/time/sys_unix.go
@@ -0,0 +1,62 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix || (js && wasm) || wasip1
+
+package time
+
+import (
+	"errors"
+	"runtime"
+	"syscall"
+)
+
+// for testing: whatever interrupts a sleep
+func interrupt() {
+	// There is no mechanism in wasi to interrupt the call to poll_oneoff
+	// used to implement runtime.usleep so this function does nothing, which
+	// somewhat defeats the purpose of TestSleep but we are still better off
+	// validating that time elapses when the process calls time.Sleep than
+	// skipping the test altogether.
+	if runtime.GOOS != "wasip1" {
+		syscall.Kill(syscall.Getpid(), syscall.SIGCHLD)
+	}
+}
+
+func open(name string) (uintptr, error) {
+	fd, err := syscall.Open(name, syscall.O_RDONLY, 0)
+	if err != nil {
+		return 0, err
+	}
+	return uintptr(fd), nil
+}
+
+func read(fd uintptr, buf []byte) (int, error) {
+	return syscall.Read(int(fd), buf)
+}
+
+func closefd(fd uintptr) {
+	syscall.Close(int(fd))
+}
+
+func preadn(fd uintptr, buf []byte, off int) error {
+	whence := seekStart
+	if off < 0 {
+		whence = seekEnd
+	}
+	if _, err := syscall.Seek(int(fd), int64(off), whence); err != nil {
+		return err
+	}
+	for len(buf) > 0 {
+		m, err := syscall.Read(int(fd), buf)
+		if m <= 0 {
+			if err == nil {
+				return errors.New("short read")
+			}
+			return err
+		}
+		buf = buf[m:]
+	}
+	return nil
+}
diff --git a/src/time/sys_windows.go b/src/time/sys_windows.go
new file mode 100644
index 0000000..78e182d
--- /dev/null
+++ b/src/time/sys_windows.go
@@ -0,0 +1,55 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+import (
+	"errors"
+	"syscall"
+)
+
+// for testing: whatever interrupts a sleep
+func interrupt() {
+}
+
+func open(name string) (uintptr, error) {
+	fd, err := syscall.Open(name, syscall.O_RDONLY, 0)
+	if err != nil {
+		// This condition solves issue https://go.dev/issue/50248
+		if err == syscall.ERROR_PATH_NOT_FOUND {
+			err = syscall.ENOENT
+		}
+		return 0, err
+	}
+	return uintptr(fd), nil
+}
+
+func read(fd uintptr, buf []byte) (int, error) {
+	return syscall.Read(syscall.Handle(fd), buf)
+}
+
+func closefd(fd uintptr) {
+	syscall.Close(syscall.Handle(fd))
+}
+
+func preadn(fd uintptr, buf []byte, off int) error {
+	whence := seekStart
+	if off < 0 {
+		whence = seekEnd
+	}
+	if _, err := syscall.Seek(syscall.Handle(fd), int64(off), whence); err != nil {
+		return err
+	}
+	for len(buf) > 0 {
+		m, err := syscall.Read(syscall.Handle(fd), buf)
+		if m <= 0 {
+			if err == nil {
+				return errors.New("short read")
+			}
+			return err
+		}
+		buf = buf[m:]
+	}
+	return nil
+}
diff --git a/src/time/testdata/2020b_Europe_Berlin b/src/time/testdata/2020b_Europe_Berlin
new file mode 100644
index 0000000..465546b
--- /dev/null
+++ b/src/time/testdata/2020b_Europe_Berlin
diff --git a/src/time/testdata/2021a_America_Nuuk b/src/time/testdata/2021a_America_Nuuk
new file mode 100644
index 0000000..4ddc99d
--- /dev/null
+++ b/src/time/testdata/2021a_America_Nuuk
diff --git a/src/time/testdata/2021a_Asia_Gaza b/src/time/testdata/2021a_Asia_Gaza
new file mode 100644
index 0000000..58e9fdf
--- /dev/null
+++ b/src/time/testdata/2021a_Asia_Gaza
diff --git a/src/time/testdata/2021a_Europe_Dublin b/src/time/testdata/2021a_Europe_Dublin
new file mode 100644
index 0000000..4a45ea8
--- /dev/null
+++ b/src/time/testdata/2021a_Europe_Dublin
diff --git a/src/time/tick.go b/src/time/tick.go
new file mode 100644
index 0000000..9da16b5
--- /dev/null
+++ b/src/time/tick.go
@@ -0,0 +1,71 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+// A Ticker holds a channel that delivers “ticks” of a clock
+// at intervals.
+type Ticker struct {
+	C <-chan Time // The channel on which the ticks are delivered.
+	r runtimeTimer
+}
+
+// NewTicker returns a new Ticker containing a channel that will send
+// the current time on the channel after each tick. The period of the
+// ticks is specified by the duration argument. The ticker will adjust
+// the time interval or drop ticks to make up for slow receivers.
+// The duration d must be greater than zero; if not, NewTicker will
+// panic. Stop the ticker to release associated resources.
+func NewTicker(d Duration) *Ticker {
+	if d <= 0 {
+		panic("non-positive interval for NewTicker")
+	}
+	// Give the channel a 1-element time buffer.
+	// If the client falls behind while reading, we drop ticks
+	// on the floor until the client catches up.
+	c := make(chan Time, 1)
+	t := &Ticker{
+		C: c,
+		r: runtimeTimer{
+			when:   when(d),
+			period: int64(d),
+			f:      sendTime,
+			arg:    c,
+		},
+	}
+	startTimer(&t.r)
+	return t
+}
+
+// Stop turns off a ticker. After Stop, no more ticks will be sent.
+// Stop does not close the channel, to prevent a concurrent goroutine
+// reading from the channel from seeing an erroneous "tick".
+func (t *Ticker) Stop() {
+	stopTimer(&t.r)
+}
+
+// Reset stops a ticker and resets its period to the specified duration.
+// The next tick will arrive after the new period elapses. The duration d
+// must be greater than zero; if not, Reset will panic.
+func (t *Ticker) Reset(d Duration) {
+	if d <= 0 {
+		panic("non-positive interval for Ticker.Reset")
+	}
+	if t.r.f == nil {
+		panic("time: Reset called on uninitialized Ticker")
+	}
+	modTimer(&t.r, when(d), int64(d), t.r.f, t.r.arg, t.r.seq)
+}
+
+// Tick is a convenience wrapper for NewTicker providing access to the ticking
+// channel only. While Tick is useful for clients that have no need to shut down
+// the Ticker, be aware that without a way to shut it down the underlying
+// Ticker cannot be recovered by the garbage collector; it "leaks".
+// Unlike NewTicker, Tick will return nil if d <= 0.
+func Tick(d Duration) <-chan Time {
+	if d <= 0 {
+		return nil
+	}
+	return NewTicker(d).C
+}
diff --git a/src/time/tick_test.go b/src/time/tick_test.go
new file mode 100644
index 0000000..f539091
--- /dev/null
+++ b/src/time/tick_test.go
@@ -0,0 +1,177 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"fmt"
+	"runtime"
+	"testing"
+	. "time"
+)
+
+func TestTicker(t *testing.T) {
+	// We want to test that a ticker takes as much time as expected.
+	// Since we don't want the test to run for too long, we don't
+	// want to use lengthy times. This makes the test inherently flaky.
+	// Start with a short time, but try again with a long one if the
+	// first test fails.
+
+	baseCount := 10
+	baseDelta := 20 * Millisecond
+
+	// On Darwin ARM64 the tick frequency seems limited. Issue 35692.
+	if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && runtime.GOARCH == "arm64" {
+		// The following test will run ticker count/2 times then reset
+		// the ticker to double the duration for the rest of count/2.
+		// Since tick frequency is limited on Darwin ARM64, use even
+		// number to give the ticks more time to let the test pass.
+		// See CL 220638.
+		baseCount = 6
+		baseDelta = 100 * Millisecond
+	}
+
+	var errs []string
+	logErrs := func() {
+		for _, e := range errs {
+			t.Log(e)
+		}
+	}
+
+	for _, test := range []struct {
+		count int
+		delta Duration
+	}{{
+		count: baseCount,
+		delta: baseDelta,
+	}, {
+		count: 8,
+		delta: 1 * Second,
+	}} {
+		count, delta := test.count, test.delta
+		ticker := NewTicker(delta)
+		t0 := Now()
+		for i := 0; i < count/2; i++ {
+			<-ticker.C
+		}
+		ticker.Reset(delta * 2)
+		for i := count / 2; i < count; i++ {
+			<-ticker.C
+		}
+		ticker.Stop()
+		t1 := Now()
+		dt := t1.Sub(t0)
+		target := 3 * delta * Duration(count/2)
+		slop := target * 3 / 10
+		if dt < target-slop || dt > target+slop {
+			errs = append(errs, fmt.Sprintf("%d %s ticks then %d %s ticks took %s, expected [%s,%s]", count/2, delta, count/2, delta*2, dt, target-slop, target+slop))
+			if dt > target+slop {
+				// System may be overloaded; sleep a bit
+				// in the hopes it will recover.
+				Sleep(Second / 2)
+			}
+			continue
+		}
+		// Now test that the ticker stopped.
+		Sleep(2 * delta)
+		select {
+		case <-ticker.C:
+			errs = append(errs, "Ticker did not shut down")
+			continue
+		default:
+			// ok
+		}
+
+		// Test passed, so all done.
+		if len(errs) > 0 {
+			t.Logf("saw %d errors, ignoring to avoid flakiness", len(errs))
+			logErrs()
+		}
+
+		return
+	}
+
+	t.Errorf("saw %d errors", len(errs))
+	logErrs()
+}
+
+// Issue 21874
+func TestTickerStopWithDirectInitialization(t *testing.T) {
+	c := make(chan Time)
+	tk := &Ticker{C: c}
+	tk.Stop()
+}
+
+// Test that a bug tearing down a ticker has been fixed. This routine should not deadlock.
+func TestTeardown(t *testing.T) {
+	Delta := 100 * Millisecond
+	if testing.Short() {
+		Delta = 20 * Millisecond
+	}
+	for i := 0; i < 3; i++ {
+		ticker := NewTicker(Delta)
+		<-ticker.C
+		ticker.Stop()
+	}
+}
+
+// Test the Tick convenience wrapper.
+func TestTick(t *testing.T) {
+	// Test that giving a negative duration returns nil.
+	if got := Tick(-1); got != nil {
+		t.Errorf("Tick(-1) = %v; want nil", got)
+	}
+}
+
+// Test that NewTicker panics when given a duration less than zero.
+func TestNewTickerLtZeroDuration(t *testing.T) {
+	defer func() {
+		if err := recover(); err == nil {
+			t.Errorf("NewTicker(-1) should have panicked")
+		}
+	}()
+	NewTicker(-1)
+}
+
+// Test that Ticker.Reset panics when given a duration less than zero.
+func TestTickerResetLtZeroDuration(t *testing.T) {
+	defer func() {
+		if err := recover(); err == nil {
+			t.Errorf("Ticker.Reset(0) should have panicked")
+		}
+	}()
+	tk := NewTicker(Second)
+	tk.Reset(0)
+}
+
+func BenchmarkTicker(b *testing.B) {
+	benchmark(b, func(n int) {
+		ticker := NewTicker(Nanosecond)
+		for i := 0; i < n; i++ {
+			<-ticker.C
+		}
+		ticker.Stop()
+	})
+}
+
+func BenchmarkTickerReset(b *testing.B) {
+	benchmark(b, func(n int) {
+		ticker := NewTicker(Nanosecond)
+		for i := 0; i < n; i++ {
+			ticker.Reset(Nanosecond * 2)
+		}
+		ticker.Stop()
+	})
+}
+
+func BenchmarkTickerResetNaive(b *testing.B) {
+	benchmark(b, func(n int) {
+		ticker := NewTicker(Nanosecond)
+		for i := 0; i < n; i++ {
+			ticker.Stop()
+			ticker = NewTicker(Nanosecond * 2)
+		}
+		ticker.Stop()
+	})
+}
diff --git a/src/time/time.go b/src/time/time.go
new file mode 100644
index 0000000..e8aac59
--- /dev/null
+++ b/src/time/time.go
@@ -0,0 +1,1646 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package time provides functionality for measuring and displaying time.
+//
+// The calendrical calculations always assume a Gregorian calendar, with
+// no leap seconds.
+//
+// # Monotonic Clocks
+//
+// Operating systems provide both a “wall clock,” which is subject to
+// changes for clock synchronization, and a “monotonic clock,” which is
+// not. The general rule is that the wall clock is for telling time and
+// the monotonic clock is for measuring time. Rather than split the API,
+// in this package the Time returned by time.Now contains both a wall
+// clock reading and a monotonic clock reading; later time-telling
+// operations use the wall clock reading, but later time-measuring
+// operations, specifically comparisons and subtractions, use the
+// monotonic clock reading.
+//
+// For example, this code always computes a positive elapsed time of
+// approximately 20 milliseconds, even if the wall clock is changed during
+// the operation being timed:
+//
+//	start := time.Now()
+//	... operation that takes 20 milliseconds ...
+//	t := time.Now()
+//	elapsed := t.Sub(start)
+//
+// Other idioms, such as time.Since(start), time.Until(deadline), and
+// time.Now().Before(deadline), are similarly robust against wall clock
+// resets.
+//
+// The rest of this section gives the precise details of how operations
+// use monotonic clocks, but understanding those details is not required
+// to use this package.
+//
+// The Time returned by time.Now contains a monotonic clock reading.
+// If Time t has a monotonic clock reading, t.Add adds the same duration to
+// both the wall clock and monotonic clock readings to compute the result.
+// Because t.AddDate(y, m, d), t.Round(d), and t.Truncate(d) are wall time
+// computations, they always strip any monotonic clock reading from their results.
+// Because t.In, t.Local, and t.UTC are used for their effect on the interpretation
+// of the wall time, they also strip any monotonic clock reading from their results.
+// The canonical way to strip a monotonic clock reading is to use t = t.Round(0).
+//
+// If Times t and u both contain monotonic clock readings, the operations
+// t.After(u), t.Before(u), t.Equal(u), t.Compare(u), and t.Sub(u) are carried out
+// using the monotonic clock readings alone, ignoring the wall clock
+// readings. If either t or u contains no monotonic clock reading, these
+// operations fall back to using the wall clock readings.
+//
+// On some systems the monotonic clock will stop if the computer goes to sleep.
+// On such a system, t.Sub(u) may not accurately reflect the actual
+// time that passed between t and u.
+//
+// Because the monotonic clock reading has no meaning outside
+// the current process, the serialized forms generated by t.GobEncode,
+// t.MarshalBinary, t.MarshalJSON, and t.MarshalText omit the monotonic
+// clock reading, and t.Format provides no format for it. Similarly, the
+// constructors time.Date, time.Parse, time.ParseInLocation, and time.Unix,
+// as well as the unmarshalers t.GobDecode, t.UnmarshalBinary.
+// t.UnmarshalJSON, and t.UnmarshalText always create times with
+// no monotonic clock reading.
+//
+// The monotonic clock reading exists only in Time values. It is not
+// a part of Duration values or the Unix times returned by t.Unix and
+// friends.
+//
+// Note that the Go == operator compares not just the time instant but
+// also the Location and the monotonic clock reading. See the
+// documentation for the Time type for a discussion of equality
+// testing for Time values.
+//
+// For debugging, the result of t.String does include the monotonic
+// clock reading if present. If t != u because of different monotonic clock readings,
+// that difference will be visible when printing t.String() and u.String().
+package time
+
+import (
+	"errors"
+	_ "unsafe" // for go:linkname
+)
+
+// A Time represents an instant in time with nanosecond precision.
+//
+// Programs using times should typically store and pass them as values,
+// not pointers. That is, time variables and struct fields should be of
+// type time.Time, not *time.Time.
+//
+// A Time value can be used by multiple goroutines simultaneously except
+// that the methods GobDecode, UnmarshalBinary, UnmarshalJSON and
+// UnmarshalText are not concurrency-safe.
+//
+// Time instants can be compared using the Before, After, and Equal methods.
+// The Sub method subtracts two instants, producing a Duration.
+// The Add method adds a Time and a Duration, producing a Time.
+//
+// The zero value of type Time is January 1, year 1, 00:00:00.000000000 UTC.
+// As this time is unlikely to come up in practice, the IsZero method gives
+// a simple way of detecting a time that has not been initialized explicitly.
+//
+// Each Time has associated with it a Location, consulted when computing the
+// presentation form of the time, such as in the Format, Hour, and Year methods.
+// The methods Local, UTC, and In return a Time with a specific location.
+// Changing the location in this way changes only the presentation; it does not
+// change the instant in time being denoted and therefore does not affect the
+// computations described in earlier paragraphs.
+//
+// Representations of a Time value saved by the GobEncode, MarshalBinary,
+// MarshalJSON, and MarshalText methods store the Time.Location's offset, but not
+// the location name. They therefore lose information about Daylight Saving Time.
+//
+// In addition to the required “wall clock” reading, a Time may contain an optional
+// reading of the current process's monotonic clock, to provide additional precision
+// for comparison or subtraction.
+// See the “Monotonic Clocks” section in the package documentation for details.
+//
+// Note that the Go == operator compares not just the time instant but also the
+// Location and the monotonic clock reading. Therefore, Time values should not
+// be used as map or database keys without first guaranteeing that the
+// identical Location has been set for all values, which can be achieved
+// through use of the UTC or Local method, and that the monotonic clock reading
+// has been stripped by setting t = t.Round(0). In general, prefer t.Equal(u)
+// to t == u, since t.Equal uses the most accurate comparison available and
+// correctly handles the case when only one of its arguments has a monotonic
+// clock reading.
+type Time struct {
+	// wall and ext encode the wall time seconds, wall time nanoseconds,
+	// and optional monotonic clock reading in nanoseconds.
+	//
+	// From high to low bit position, wall encodes a 1-bit flag (hasMonotonic),
+	// a 33-bit seconds field, and a 30-bit wall time nanoseconds field.
+	// The nanoseconds field is in the range [0, 999999999].
+	// If the hasMonotonic bit is 0, then the 33-bit field must be zero
+	// and the full signed 64-bit wall seconds since Jan 1 year 1 is stored in ext.
+	// If the hasMonotonic bit is 1, then the 33-bit field holds a 33-bit
+	// unsigned wall seconds since Jan 1 year 1885, and ext holds a
+	// signed 64-bit monotonic clock reading, nanoseconds since process start.
+	wall uint64
+	ext  int64
+
+	// loc specifies the Location that should be used to
+	// determine the minute, hour, month, day, and year
+	// that correspond to this Time.
+	// The nil location means UTC.
+	// All UTC times are represented with loc==nil, never loc==&utcLoc.
+	loc *Location
+}
+
+const (
+	hasMonotonic = 1 << 63
+	maxWall      = wallToInternal + (1<<33 - 1) // year 2157
+	minWall      = wallToInternal               // year 1885
+	nsecMask     = 1<<30 - 1
+	nsecShift    = 30
+)
+
+// These helpers for manipulating the wall and monotonic clock readings
+// take pointer receivers, even when they don't modify the time,
+// to make them cheaper to call.
+
+// nsec returns the time's nanoseconds.
+func (t *Time) nsec() int32 {
+	return int32(t.wall & nsecMask)
+}
+
+// sec returns the time's seconds since Jan 1 year 1.
+func (t *Time) sec() int64 {
+	if t.wall&hasMonotonic != 0 {
+		return wallToInternal + int64(t.wall<<1>>(nsecShift+1))
+	}
+	return t.ext
+}
+
+// unixSec returns the time's seconds since Jan 1 1970 (Unix time).
+func (t *Time) unixSec() int64 { return t.sec() + internalToUnix }
+
+// addSec adds d seconds to the time.
+func (t *Time) addSec(d int64) {
+	if t.wall&hasMonotonic != 0 {
+		sec := int64(t.wall << 1 >> (nsecShift + 1))
+		dsec := sec + d
+		if 0 <= dsec && dsec <= 1<<33-1 {
+			t.wall = t.wall&nsecMask | uint64(dsec)<<nsecShift | hasMonotonic
+			return
+		}
+		// Wall second now out of range for packed field.
+		// Move to ext.
+		t.stripMono()
+	}
+
+	// Check if the sum of t.ext and d overflows and handle it properly.
+	sum := t.ext + d
+	if (sum > t.ext) == (d > 0) {
+		t.ext = sum
+	} else if d > 0 {
+		t.ext = 1<<63 - 1
+	} else {
+		t.ext = -(1<<63 - 1)
+	}
+}
+
+// setLoc sets the location associated with the time.
+func (t *Time) setLoc(loc *Location) {
+	if loc == &utcLoc {
+		loc = nil
+	}
+	t.stripMono()
+	t.loc = loc
+}
+
+// stripMono strips the monotonic clock reading in t.
+func (t *Time) stripMono() {
+	if t.wall&hasMonotonic != 0 {
+		t.ext = t.sec()
+		t.wall &= nsecMask
+	}
+}
+
+// setMono sets the monotonic clock reading in t.
+// If t cannot hold a monotonic clock reading,
+// because its wall time is too large,
+// setMono is a no-op.
+func (t *Time) setMono(m int64) {
+	if t.wall&hasMonotonic == 0 {
+		sec := t.ext
+		if sec < minWall || maxWall < sec {
+			return
+		}
+		t.wall |= hasMonotonic | uint64(sec-minWall)<<nsecShift
+	}
+	t.ext = m
+}
+
+// mono returns t's monotonic clock reading.
+// It returns 0 for a missing reading.
+// This function is used only for testing,
+// so it's OK that technically 0 is a valid
+// monotonic clock reading as well.
+func (t *Time) mono() int64 {
+	if t.wall&hasMonotonic == 0 {
+		return 0
+	}
+	return t.ext
+}
+
+// After reports whether the time instant t is after u.
+func (t Time) After(u Time) bool {
+	if t.wall&u.wall&hasMonotonic != 0 {
+		return t.ext > u.ext
+	}
+	ts := t.sec()
+	us := u.sec()
+	return ts > us || ts == us && t.nsec() > u.nsec()
+}
+
+// Before reports whether the time instant t is before u.
+func (t Time) Before(u Time) bool {
+	if t.wall&u.wall&hasMonotonic != 0 {
+		return t.ext < u.ext
+	}
+	ts := t.sec()
+	us := u.sec()
+	return ts < us || ts == us && t.nsec() < u.nsec()
+}
+
+// Compare compares the time instant t with u. If t is before u, it returns -1;
+// if t is after u, it returns +1; if they're the same, it returns 0.
+func (t Time) Compare(u Time) int {
+	var tc, uc int64
+	if t.wall&u.wall&hasMonotonic != 0 {
+		tc, uc = t.ext, u.ext
+	} else {
+		tc, uc = t.sec(), u.sec()
+		if tc == uc {
+			tc, uc = int64(t.nsec()), int64(u.nsec())
+		}
+	}
+	switch {
+	case tc < uc:
+		return -1
+	case tc > uc:
+		return +1
+	}
+	return 0
+}
+
+// Equal reports whether t and u represent the same time instant.
+// Two times can be equal even if they are in different locations.
+// For example, 6:00 +0200 and 4:00 UTC are Equal.
+// See the documentation on the Time type for the pitfalls of using == with
+// Time values; most code should use Equal instead.
+func (t Time) Equal(u Time) bool {
+	if t.wall&u.wall&hasMonotonic != 0 {
+		return t.ext == u.ext
+	}
+	return t.sec() == u.sec() && t.nsec() == u.nsec()
+}
+
+// A Month specifies a month of the year (January = 1, ...).
+type Month int
+
+const (
+	January Month = 1 + iota
+	February
+	March
+	April
+	May
+	June
+	July
+	August
+	September
+	October
+	November
+	December
+)
+
+// String returns the English name of the month ("January", "February", ...).
+func (m Month) String() string {
+	if January <= m && m <= December {
+		return longMonthNames[m-1]
+	}
+	buf := make([]byte, 20)
+	n := fmtInt(buf, uint64(m))
+	return "%!Month(" + string(buf[n:]) + ")"
+}
+
+// A Weekday specifies a day of the week (Sunday = 0, ...).
+type Weekday int
+
+const (
+	Sunday Weekday = iota
+	Monday
+	Tuesday
+	Wednesday
+	Thursday
+	Friday
+	Saturday
+)
+
+// String returns the English name of the day ("Sunday", "Monday", ...).
+func (d Weekday) String() string {
+	if Sunday <= d && d <= Saturday {
+		return longDayNames[d]
+	}
+	buf := make([]byte, 20)
+	n := fmtInt(buf, uint64(d))
+	return "%!Weekday(" + string(buf[n:]) + ")"
+}
+
+// Computations on time.
+//
+// The zero value for a Time is defined to be
+//	January 1, year 1, 00:00:00.000000000 UTC
+// which (1) looks like a zero, or as close as you can get in a date
+// (1-1-1 00:00:00 UTC), (2) is unlikely enough to arise in practice to
+// be a suitable "not set" sentinel, unlike Jan 1 1970, and (3) has a
+// non-negative year even in time zones west of UTC, unlike 1-1-0
+// 00:00:00 UTC, which would be 12-31-(-1) 19:00:00 in New York.
+//
+// The zero Time value does not force a specific epoch for the time
+// representation. For example, to use the Unix epoch internally, we
+// could define that to distinguish a zero value from Jan 1 1970, that
+// time would be represented by sec=-1, nsec=1e9. However, it does
+// suggest a representation, namely using 1-1-1 00:00:00 UTC as the
+// epoch, and that's what we do.
+//
+// The Add and Sub computations are oblivious to the choice of epoch.
+//
+// The presentation computations - year, month, minute, and so on - all
+// rely heavily on division and modulus by positive constants. For
+// calendrical calculations we want these divisions to round down, even
+// for negative values, so that the remainder is always positive, but
+// Go's division (like most hardware division instructions) rounds to
+// zero. We can still do those computations and then adjust the result
+// for a negative numerator, but it's annoying to write the adjustment
+// over and over. Instead, we can change to a different epoch so long
+// ago that all the times we care about will be positive, and then round
+// to zero and round down coincide. These presentation routines already
+// have to add the zone offset, so adding the translation to the
+// alternate epoch is cheap. For example, having a non-negative time t
+// means that we can write
+//
+//	sec = t % 60
+//
+// instead of
+//
+//	sec = t % 60
+//	if sec < 0 {
+//		sec += 60
+//	}
+//
+// everywhere.
+//
+// The calendar runs on an exact 400 year cycle: a 400-year calendar
+// printed for 1970-2369 will apply as well to 2370-2769. Even the days
+// of the week match up. It simplifies the computations to choose the
+// cycle boundaries so that the exceptional years are always delayed as
+// long as possible. That means choosing a year equal to 1 mod 400, so
+// that the first leap year is the 4th year, the first missed leap year
+// is the 100th year, and the missed missed leap year is the 400th year.
+// So we'd prefer instead to print a calendar for 2001-2400 and reuse it
+// for 2401-2800.
+//
+// Finally, it's convenient if the delta between the Unix epoch and
+// long-ago epoch is representable by an int64 constant.
+//
+// These three considerations—choose an epoch as early as possible, that
+// uses a year equal to 1 mod 400, and that is no more than 2⁶³ seconds
+// earlier than 1970—bring us to the year -292277022399. We refer to
+// this year as the absolute zero year, and to times measured as a uint64
+// seconds since this year as absolute times.
+//
+// Times measured as an int64 seconds since the year 1—the representation
+// used for Time's sec field—are called internal times.
+//
+// Times measured as an int64 seconds since the year 1970 are called Unix
+// times.
+//
+// It is tempting to just use the year 1 as the absolute epoch, defining
+// that the routines are only valid for years >= 1. However, the
+// routines would then be invalid when displaying the epoch in time zones
+// west of UTC, since it is year 0. It doesn't seem tenable to say that
+// printing the zero time correctly isn't supported in half the time
+// zones. By comparison, it's reasonable to mishandle some times in
+// the year -292277022399.
+//
+// All this is opaque to clients of the API and can be changed if a
+// better implementation presents itself.
+
+const (
+	// The unsigned zero year for internal calculations.
+	// Must be 1 mod 400, and times before it will not compute correctly,
+	// but otherwise can be changed at will.
+	absoluteZeroYear = -292277022399
+
+	// The year of the zero Time.
+	// Assumed by the unixToInternal computation below.
+	internalYear = 1
+
+	// Offsets to convert between internal and absolute or Unix times.
+	absoluteToInternal int64 = (absoluteZeroYear - internalYear) * 365.2425 * secondsPerDay
+	internalToAbsolute       = -absoluteToInternal
+
+	unixToInternal int64 = (1969*365 + 1969/4 - 1969/100 + 1969/400) * secondsPerDay
+	internalToUnix int64 = -unixToInternal
+
+	wallToInternal int64 = (1884*365 + 1884/4 - 1884/100 + 1884/400) * secondsPerDay
+)
+
+// IsZero reports whether t represents the zero time instant,
+// January 1, year 1, 00:00:00 UTC.
+func (t Time) IsZero() bool {
+	return t.sec() == 0 && t.nsec() == 0
+}
+
+// abs returns the time t as an absolute time, adjusted by the zone offset.
+// It is called when computing a presentation property like Month or Hour.
+func (t Time) abs() uint64 {
+	l := t.loc
+	// Avoid function calls when possible.
+	if l == nil || l == &localLoc {
+		l = l.get()
+	}
+	sec := t.unixSec()
+	if l != &utcLoc {
+		if l.cacheZone != nil && l.cacheStart <= sec && sec < l.cacheEnd {
+			sec += int64(l.cacheZone.offset)
+		} else {
+			_, offset, _, _, _ := l.lookup(sec)
+			sec += int64(offset)
+		}
+	}
+	return uint64(sec + (unixToInternal + internalToAbsolute))
+}
+
+// locabs is a combination of the Zone and abs methods,
+// extracting both return values from a single zone lookup.
+func (t Time) locabs() (name string, offset int, abs uint64) {
+	l := t.loc
+	if l == nil || l == &localLoc {
+		l = l.get()
+	}
+	// Avoid function call if we hit the local time cache.
+	sec := t.unixSec()
+	if l != &utcLoc {
+		if l.cacheZone != nil && l.cacheStart <= sec && sec < l.cacheEnd {
+			name = l.cacheZone.name
+			offset = l.cacheZone.offset
+		} else {
+			name, offset, _, _, _ = l.lookup(sec)
+		}
+		sec += int64(offset)
+	} else {
+		name = "UTC"
+	}
+	abs = uint64(sec + (unixToInternal + internalToAbsolute))
+	return
+}
+
+// Date returns the year, month, and day in which t occurs.
+func (t Time) Date() (year int, month Month, day int) {
+	year, month, day, _ = t.date(true)
+	return
+}
+
+// Year returns the year in which t occurs.
+func (t Time) Year() int {
+	year, _, _, _ := t.date(false)
+	return year
+}
+
+// Month returns the month of the year specified by t.
+func (t Time) Month() Month {
+	_, month, _, _ := t.date(true)
+	return month
+}
+
+// Day returns the day of the month specified by t.
+func (t Time) Day() int {
+	_, _, day, _ := t.date(true)
+	return day
+}
+
+// Weekday returns the day of the week specified by t.
+func (t Time) Weekday() Weekday {
+	return absWeekday(t.abs())
+}
+
+// absWeekday is like Weekday but operates on an absolute time.
+func absWeekday(abs uint64) Weekday {
+	// January 1 of the absolute year, like January 1 of 2001, was a Monday.
+	sec := (abs + uint64(Monday)*secondsPerDay) % secondsPerWeek
+	return Weekday(int(sec) / secondsPerDay)
+}
+
+// ISOWeek returns the ISO 8601 year and week number in which t occurs.
+// Week ranges from 1 to 53. Jan 01 to Jan 03 of year n might belong to
+// week 52 or 53 of year n-1, and Dec 29 to Dec 31 might belong to week 1
+// of year n+1.
+func (t Time) ISOWeek() (year, week int) {
+	// According to the rule that the first calendar week of a calendar year is
+	// the week including the first Thursday of that year, and that the last one is
+	// the week immediately preceding the first calendar week of the next calendar year.
+	// See https://www.iso.org/obp/ui#iso:std:iso:8601:-1:ed-1:v1:en:term:3.1.1.23 for details.
+
+	// weeks start with Monday
+	// Monday Tuesday Wednesday Thursday Friday Saturday Sunday
+	// 1      2       3         4        5      6        7
+	// +3     +2      +1        0        -1     -2       -3
+	// the offset to Thursday
+	abs := t.abs()
+	d := Thursday - absWeekday(abs)
+	// handle Sunday
+	if d == 4 {
+		d = -3
+	}
+	// find the Thursday of the calendar week
+	abs += uint64(d) * secondsPerDay
+	year, _, _, yday := absDate(abs, false)
+	return year, yday/7 + 1
+}
+
+// Clock returns the hour, minute, and second within the day specified by t.
+func (t Time) Clock() (hour, min, sec int) {
+	return absClock(t.abs())
+}
+
+// absClock is like clock but operates on an absolute time.
+func absClock(abs uint64) (hour, min, sec int) {
+	sec = int(abs % secondsPerDay)
+	hour = sec / secondsPerHour
+	sec -= hour * secondsPerHour
+	min = sec / secondsPerMinute
+	sec -= min * secondsPerMinute
+	return
+}
+
+// Hour returns the hour within the day specified by t, in the range [0, 23].
+func (t Time) Hour() int {
+	return int(t.abs()%secondsPerDay) / secondsPerHour
+}
+
+// Minute returns the minute offset within the hour specified by t, in the range [0, 59].
+func (t Time) Minute() int {
+	return int(t.abs()%secondsPerHour) / secondsPerMinute
+}
+
+// Second returns the second offset within the minute specified by t, in the range [0, 59].
+func (t Time) Second() int {
+	return int(t.abs() % secondsPerMinute)
+}
+
+// Nanosecond returns the nanosecond offset within the second specified by t,
+// in the range [0, 999999999].
+func (t Time) Nanosecond() int {
+	return int(t.nsec())
+}
+
+// YearDay returns the day of the year specified by t, in the range [1,365] for non-leap years,
+// and [1,366] in leap years.
+func (t Time) YearDay() int {
+	_, _, _, yday := t.date(false)
+	return yday + 1
+}
+
+// A Duration represents the elapsed time between two instants
+// as an int64 nanosecond count. The representation limits the
+// largest representable duration to approximately 290 years.
+type Duration int64
+
+const (
+	minDuration Duration = -1 << 63
+	maxDuration Duration = 1<<63 - 1
+)
+
+// Common durations. There is no definition for units of Day or larger
+// to avoid confusion across daylight savings time zone transitions.
+//
+// To count the number of units in a Duration, divide:
+//
+//	second := time.Second
+//	fmt.Print(int64(second/time.Millisecond)) // prints 1000
+//
+// To convert an integer number of units to a Duration, multiply:
+//
+//	seconds := 10
+//	fmt.Print(time.Duration(seconds)*time.Second) // prints 10s
+const (
+	Nanosecond  Duration = 1
+	Microsecond          = 1000 * Nanosecond
+	Millisecond          = 1000 * Microsecond
+	Second               = 1000 * Millisecond
+	Minute               = 60 * Second
+	Hour                 = 60 * Minute
+)
+
+// String returns a string representing the duration in the form "72h3m0.5s".
+// Leading zero units are omitted. As a special case, durations less than one
+// second format use a smaller unit (milli-, micro-, or nanoseconds) to ensure
+// that the leading digit is non-zero. The zero duration formats as 0s.
+func (d Duration) String() string {
+	// Largest time is 2540400h10m10.000000000s
+	var buf [32]byte
+	w := len(buf)
+
+	u := uint64(d)
+	neg := d < 0
+	if neg {
+		u = -u
+	}
+
+	if u < uint64(Second) {
+		// Special case: if duration is smaller than a second,
+		// use smaller units, like 1.2ms
+		var prec int
+		w--
+		buf[w] = 's'
+		w--
+		switch {
+		case u == 0:
+			return "0s"
+		case u < uint64(Microsecond):
+			// print nanoseconds
+			prec = 0
+			buf[w] = 'n'
+		case u < uint64(Millisecond):
+			// print microseconds
+			prec = 3
+			// U+00B5 'µ' micro sign == 0xC2 0xB5
+			w-- // Need room for two bytes.
+			copy(buf[w:], "µ")
+		default:
+			// print milliseconds
+			prec = 6
+			buf[w] = 'm'
+		}
+		w, u = fmtFrac(buf[:w], u, prec)
+		w = fmtInt(buf[:w], u)
+	} else {
+		w--
+		buf[w] = 's'
+
+		w, u = fmtFrac(buf[:w], u, 9)
+
+		// u is now integer seconds
+		w = fmtInt(buf[:w], u%60)
+		u /= 60
+
+		// u is now integer minutes
+		if u > 0 {
+			w--
+			buf[w] = 'm'
+			w = fmtInt(buf[:w], u%60)
+			u /= 60
+
+			// u is now integer hours
+			// Stop at hours because days can be different lengths.
+			if u > 0 {
+				w--
+				buf[w] = 'h'
+				w = fmtInt(buf[:w], u)
+			}
+		}
+	}
+
+	if neg {
+		w--
+		buf[w] = '-'
+	}
+
+	return string(buf[w:])
+}
+
+// fmtFrac formats the fraction of v/10**prec (e.g., ".12345") into the
+// tail of buf, omitting trailing zeros. It omits the decimal
+// point too when the fraction is 0. It returns the index where the
+// output bytes begin and the value v/10**prec.
+func fmtFrac(buf []byte, v uint64, prec int) (nw int, nv uint64) {
+	// Omit trailing zeros up to and including decimal point.
+	w := len(buf)
+	print := false
+	for i := 0; i < prec; i++ {
+		digit := v % 10
+		print = print || digit != 0
+		if print {
+			w--
+			buf[w] = byte(digit) + '0'
+		}
+		v /= 10
+	}
+	if print {
+		w--
+		buf[w] = '.'
+	}
+	return w, v
+}
+
+// fmtInt formats v into the tail of buf.
+// It returns the index where the output begins.
+func fmtInt(buf []byte, v uint64) int {
+	w := len(buf)
+	if v == 0 {
+		w--
+		buf[w] = '0'
+	} else {
+		for v > 0 {
+			w--
+			buf[w] = byte(v%10) + '0'
+			v /= 10
+		}
+	}
+	return w
+}
+
+// Nanoseconds returns the duration as an integer nanosecond count.
+func (d Duration) Nanoseconds() int64 { return int64(d) }
+
+// Microseconds returns the duration as an integer microsecond count.
+func (d Duration) Microseconds() int64 { return int64(d) / 1e3 }
+
+// Milliseconds returns the duration as an integer millisecond count.
+func (d Duration) Milliseconds() int64 { return int64(d) / 1e6 }
+
+// These methods return float64 because the dominant
+// use case is for printing a floating point number like 1.5s, and
+// a truncation to integer would make them not useful in those cases.
+// Splitting the integer and fraction ourselves guarantees that
+// converting the returned float64 to an integer rounds the same
+// way that a pure integer conversion would have, even in cases
+// where, say, float64(d.Nanoseconds())/1e9 would have rounded
+// differently.
+
+// Seconds returns the duration as a floating point number of seconds.
+func (d Duration) Seconds() float64 {
+	sec := d / Second
+	nsec := d % Second
+	return float64(sec) + float64(nsec)/1e9
+}
+
+// Minutes returns the duration as a floating point number of minutes.
+func (d Duration) Minutes() float64 {
+	min := d / Minute
+	nsec := d % Minute
+	return float64(min) + float64(nsec)/(60*1e9)
+}
+
+// Hours returns the duration as a floating point number of hours.
+func (d Duration) Hours() float64 {
+	hour := d / Hour
+	nsec := d % Hour
+	return float64(hour) + float64(nsec)/(60*60*1e9)
+}
+
+// Truncate returns the result of rounding d toward zero to a multiple of m.
+// If m <= 0, Truncate returns d unchanged.
+func (d Duration) Truncate(m Duration) Duration {
+	if m <= 0 {
+		return d
+	}
+	return d - d%m
+}
+
+// lessThanHalf reports whether x+x < y but avoids overflow,
+// assuming x and y are both positive (Duration is signed).
+func lessThanHalf(x, y Duration) bool {
+	return uint64(x)+uint64(x) < uint64(y)
+}
+
+// Round returns the result of rounding d to the nearest multiple of m.
+// The rounding behavior for halfway values is to round away from zero.
+// If the result exceeds the maximum (or minimum)
+// value that can be stored in a Duration,
+// Round returns the maximum (or minimum) duration.
+// If m <= 0, Round returns d unchanged.
+func (d Duration) Round(m Duration) Duration {
+	if m <= 0 {
+		return d
+	}
+	r := d % m
+	if d < 0 {
+		r = -r
+		if lessThanHalf(r, m) {
+			return d + r
+		}
+		if d1 := d - m + r; d1 < d {
+			return d1
+		}
+		return minDuration // overflow
+	}
+	if lessThanHalf(r, m) {
+		return d - r
+	}
+	if d1 := d + m - r; d1 > d {
+		return d1
+	}
+	return maxDuration // overflow
+}
+
+// Abs returns the absolute value of d.
+// As a special case, math.MinInt64 is converted to math.MaxInt64.
+func (d Duration) Abs() Duration {
+	switch {
+	case d >= 0:
+		return d
+	case d == minDuration:
+		return maxDuration
+	default:
+		return -d
+	}
+}
+
+// Add returns the time t+d.
+func (t Time) Add(d Duration) Time {
+	dsec := int64(d / 1e9)
+	nsec := t.nsec() + int32(d%1e9)
+	if nsec >= 1e9 {
+		dsec++
+		nsec -= 1e9
+	} else if nsec < 0 {
+		dsec--
+		nsec += 1e9
+	}
+	t.wall = t.wall&^nsecMask | uint64(nsec) // update nsec
+	t.addSec(dsec)
+	if t.wall&hasMonotonic != 0 {
+		te := t.ext + int64(d)
+		if d < 0 && te > t.ext || d > 0 && te < t.ext {
+			// Monotonic clock reading now out of range; degrade to wall-only.
+			t.stripMono()
+		} else {
+			t.ext = te
+		}
+	}
+	return t
+}
+
+// Sub returns the duration t-u. If the result exceeds the maximum (or minimum)
+// value that can be stored in a Duration, the maximum (or minimum) duration
+// will be returned.
+// To compute t-d for a duration d, use t.Add(-d).
+func (t Time) Sub(u Time) Duration {
+	if t.wall&u.wall&hasMonotonic != 0 {
+		te := t.ext
+		ue := u.ext
+		d := Duration(te - ue)
+		if d < 0 && te > ue {
+			return maxDuration // t - u is positive out of range
+		}
+		if d > 0 && te < ue {
+			return minDuration // t - u is negative out of range
+		}
+		return d
+	}
+	d := Duration(t.sec()-u.sec())*Second + Duration(t.nsec()-u.nsec())
+	// Check for overflow or underflow.
+	switch {
+	case u.Add(d).Equal(t):
+		return d // d is correct
+	case t.Before(u):
+		return minDuration // t - u is negative out of range
+	default:
+		return maxDuration // t - u is positive out of range
+	}
+}
+
+// Since returns the time elapsed since t.
+// It is shorthand for time.Now().Sub(t).
+func Since(t Time) Duration {
+	var now Time
+	if t.wall&hasMonotonic != 0 {
+		// Common case optimization: if t has monotonic time, then Sub will use only it.
+		now = Time{hasMonotonic, runtimeNano() - startNano, nil}
+	} else {
+		now = Now()
+	}
+	return now.Sub(t)
+}
+
+// Until returns the duration until t.
+// It is shorthand for t.Sub(time.Now()).
+func Until(t Time) Duration {
+	var now Time
+	if t.wall&hasMonotonic != 0 {
+		// Common case optimization: if t has monotonic time, then Sub will use only it.
+		now = Time{hasMonotonic, runtimeNano() - startNano, nil}
+	} else {
+		now = Now()
+	}
+	return t.Sub(now)
+}
+
+// AddDate returns the time corresponding to adding the
+// given number of years, months, and days to t.
+// For example, AddDate(-1, 2, 3) applied to January 1, 2011
+// returns March 4, 2010.
+//
+// AddDate normalizes its result in the same way that Date does,
+// so, for example, adding one month to October 31 yields
+// December 1, the normalized form for November 31.
+func (t Time) AddDate(years int, months int, days int) Time {
+	year, month, day := t.Date()
+	hour, min, sec := t.Clock()
+	return Date(year+years, month+Month(months), day+days, hour, min, sec, int(t.nsec()), t.Location())
+}
+
+const (
+	secondsPerMinute = 60
+	secondsPerHour   = 60 * secondsPerMinute
+	secondsPerDay    = 24 * secondsPerHour
+	secondsPerWeek   = 7 * secondsPerDay
+	daysPer400Years  = 365*400 + 97
+	daysPer100Years  = 365*100 + 24
+	daysPer4Years    = 365*4 + 1
+)
+
+// date computes the year, day of year, and when full=true,
+// the month and day in which t occurs.
+func (t Time) date(full bool) (year int, month Month, day int, yday int) {
+	return absDate(t.abs(), full)
+}
+
+// absDate is like date but operates on an absolute time.
+func absDate(abs uint64, full bool) (year int, month Month, day int, yday int) {
+	// Split into time and day.
+	d := abs / secondsPerDay
+
+	// Account for 400 year cycles.
+	n := d / daysPer400Years
+	y := 400 * n
+	d -= daysPer400Years * n
+
+	// Cut off 100-year cycles.
+	// The last cycle has one extra leap year, so on the last day
+	// of that year, day / daysPer100Years will be 4 instead of 3.
+	// Cut it back down to 3 by subtracting n>>2.
+	n = d / daysPer100Years
+	n -= n >> 2
+	y += 100 * n
+	d -= daysPer100Years * n
+
+	// Cut off 4-year cycles.
+	// The last cycle has a missing leap year, which does not
+	// affect the computation.
+	n = d / daysPer4Years
+	y += 4 * n
+	d -= daysPer4Years * n
+
+	// Cut off years within a 4-year cycle.
+	// The last year is a leap year, so on the last day of that year,
+	// day / 365 will be 4 instead of 3. Cut it back down to 3
+	// by subtracting n>>2.
+	n = d / 365
+	n -= n >> 2
+	y += n
+	d -= 365 * n
+
+	year = int(int64(y) + absoluteZeroYear)
+	yday = int(d)
+
+	if !full {
+		return
+	}
+
+	day = yday
+	if isLeap(year) {
+		// Leap year
+		switch {
+		case day > 31+29-1:
+			// After leap day; pretend it wasn't there.
+			day--
+		case day == 31+29-1:
+			// Leap day.
+			month = February
+			day = 29
+			return
+		}
+	}
+
+	// Estimate month on assumption that every month has 31 days.
+	// The estimate may be too low by at most one month, so adjust.
+	month = Month(day / 31)
+	end := int(daysBefore[month+1])
+	var begin int
+	if day >= end {
+		month++
+		begin = end
+	} else {
+		begin = int(daysBefore[month])
+	}
+
+	month++ // because January is 1
+	day = day - begin + 1
+	return
+}
+
+// daysBefore[m] counts the number of days in a non-leap year
+// before month m begins. There is an entry for m=12, counting
+// the number of days before January of next year (365).
+var daysBefore = [...]int32{
+	0,
+	31,
+	31 + 28,
+	31 + 28 + 31,
+	31 + 28 + 31 + 30,
+	31 + 28 + 31 + 30 + 31,
+	31 + 28 + 31 + 30 + 31 + 30,
+	31 + 28 + 31 + 30 + 31 + 30 + 31,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30 + 31,
+}
+
+func daysIn(m Month, year int) int {
+	if m == February && isLeap(year) {
+		return 29
+	}
+	return int(daysBefore[m] - daysBefore[m-1])
+}
+
+// daysSinceEpoch takes a year and returns the number of days from
+// the absolute epoch to the start of that year.
+// This is basically (year - zeroYear) * 365, but accounting for leap days.
+func daysSinceEpoch(year int) uint64 {
+	y := uint64(int64(year) - absoluteZeroYear)
+
+	// Add in days from 400-year cycles.
+	n := y / 400
+	y -= 400 * n
+	d := daysPer400Years * n
+
+	// Add in 100-year cycles.
+	n = y / 100
+	y -= 100 * n
+	d += daysPer100Years * n
+
+	// Add in 4-year cycles.
+	n = y / 4
+	y -= 4 * n
+	d += daysPer4Years * n
+
+	// Add in non-leap years.
+	n = y
+	d += 365 * n
+
+	return d
+}
+
+// Provided by package runtime.
+func now() (sec int64, nsec int32, mono int64)
+
+// runtimeNano returns the current value of the runtime clock in nanoseconds.
+//
+//go:linkname runtimeNano runtime.nanotime
+func runtimeNano() int64
+
+// Monotonic times are reported as offsets from startNano.
+// We initialize startNano to runtimeNano() - 1 so that on systems where
+// monotonic time resolution is fairly low (e.g. Windows 2008
+// which appears to have a default resolution of 15ms),
+// we avoid ever reporting a monotonic time of 0.
+// (Callers may want to use 0 as "time not set".)
+var startNano int64 = runtimeNano() - 1
+
+// Now returns the current local time.
+func Now() Time {
+	sec, nsec, mono := now()
+	mono -= startNano
+	sec += unixToInternal - minWall
+	if uint64(sec)>>33 != 0 {
+		// Seconds field overflowed the 33 bits available when
+		// storing a monotonic time. This will be true after
+		// March 16, 2157.
+		return Time{uint64(nsec), sec + minWall, Local}
+	}
+	return Time{hasMonotonic | uint64(sec)<<nsecShift | uint64(nsec), mono, Local}
+}
+
+func unixTime(sec int64, nsec int32) Time {
+	return Time{uint64(nsec), sec + unixToInternal, Local}
+}
+
+// UTC returns t with the location set to UTC.
+func (t Time) UTC() Time {
+	t.setLoc(&utcLoc)
+	return t
+}
+
+// Local returns t with the location set to local time.
+func (t Time) Local() Time {
+	t.setLoc(Local)
+	return t
+}
+
+// In returns a copy of t representing the same time instant, but
+// with the copy's location information set to loc for display
+// purposes.
+//
+// In panics if loc is nil.
+func (t Time) In(loc *Location) Time {
+	if loc == nil {
+		panic("time: missing Location in call to Time.In")
+	}
+	t.setLoc(loc)
+	return t
+}
+
+// Location returns the time zone information associated with t.
+func (t Time) Location() *Location {
+	l := t.loc
+	if l == nil {
+		l = UTC
+	}
+	return l
+}
+
+// Zone computes the time zone in effect at time t, returning the abbreviated
+// name of the zone (such as "CET") and its offset in seconds east of UTC.
+func (t Time) Zone() (name string, offset int) {
+	name, offset, _, _, _ = t.loc.lookup(t.unixSec())
+	return
+}
+
+// ZoneBounds returns the bounds of the time zone in effect at time t.
+// The zone begins at start and the next zone begins at end.
+// If the zone begins at the beginning of time, start will be returned as a zero Time.
+// If the zone goes on forever, end will be returned as a zero Time.
+// The Location of the returned times will be the same as t.
+func (t Time) ZoneBounds() (start, end Time) {
+	_, _, startSec, endSec, _ := t.loc.lookup(t.unixSec())
+	if startSec != alpha {
+		start = unixTime(startSec, 0)
+		start.setLoc(t.loc)
+	}
+	if endSec != omega {
+		end = unixTime(endSec, 0)
+		end.setLoc(t.loc)
+	}
+	return
+}
+
+// Unix returns t as a Unix time, the number of seconds elapsed
+// since January 1, 1970 UTC. The result does not depend on the
+// location associated with t.
+// Unix-like operating systems often record time as a 32-bit
+// count of seconds, but since the method here returns a 64-bit
+// value it is valid for billions of years into the past or future.
+func (t Time) Unix() int64 {
+	return t.unixSec()
+}
+
+// UnixMilli returns t as a Unix time, the number of milliseconds elapsed since
+// January 1, 1970 UTC. The result is undefined if the Unix time in
+// milliseconds cannot be represented by an int64 (a date more than 292 million
+// years before or after 1970). The result does not depend on the
+// location associated with t.
+func (t Time) UnixMilli() int64 {
+	return t.unixSec()*1e3 + int64(t.nsec())/1e6
+}
+
+// UnixMicro returns t as a Unix time, the number of microseconds elapsed since
+// January 1, 1970 UTC. The result is undefined if the Unix time in
+// microseconds cannot be represented by an int64 (a date before year -290307 or
+// after year 294246). The result does not depend on the location associated
+// with t.
+func (t Time) UnixMicro() int64 {
+	return t.unixSec()*1e6 + int64(t.nsec())/1e3
+}
+
+// UnixNano returns t as a Unix time, the number of nanoseconds elapsed
+// since January 1, 1970 UTC. The result is undefined if the Unix time
+// in nanoseconds cannot be represented by an int64 (a date before the year
+// 1678 or after 2262). Note that this means the result of calling UnixNano
+// on the zero Time is undefined. The result does not depend on the
+// location associated with t.
+func (t Time) UnixNano() int64 {
+	return (t.unixSec())*1e9 + int64(t.nsec())
+}
+
+const (
+	timeBinaryVersionV1 byte = iota + 1 // For general situation
+	timeBinaryVersionV2                 // For LMT only
+)
+
+// MarshalBinary implements the encoding.BinaryMarshaler interface.
+func (t Time) MarshalBinary() ([]byte, error) {
+	var offsetMin int16 // minutes east of UTC. -1 is UTC.
+	var offsetSec int8
+	version := timeBinaryVersionV1
+
+	if t.Location() == UTC {
+		offsetMin = -1
+	} else {
+		_, offset := t.Zone()
+		if offset%60 != 0 {
+			version = timeBinaryVersionV2
+			offsetSec = int8(offset % 60)
+		}
+
+		offset /= 60
+		if offset < -32768 || offset == -1 || offset > 32767 {
+			return nil, errors.New("Time.MarshalBinary: unexpected zone offset")
+		}
+		offsetMin = int16(offset)
+	}
+
+	sec := t.sec()
+	nsec := t.nsec()
+	enc := []byte{
+		version,         // byte 0 : version
+		byte(sec >> 56), // bytes 1-8: seconds
+		byte(sec >> 48),
+		byte(sec >> 40),
+		byte(sec >> 32),
+		byte(sec >> 24),
+		byte(sec >> 16),
+		byte(sec >> 8),
+		byte(sec),
+		byte(nsec >> 24), // bytes 9-12: nanoseconds
+		byte(nsec >> 16),
+		byte(nsec >> 8),
+		byte(nsec),
+		byte(offsetMin >> 8), // bytes 13-14: zone offset in minutes
+		byte(offsetMin),
+	}
+	if version == timeBinaryVersionV2 {
+		enc = append(enc, byte(offsetSec))
+	}
+
+	return enc, nil
+}
+
+// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
+func (t *Time) UnmarshalBinary(data []byte) error {
+	buf := data
+	if len(buf) == 0 {
+		return errors.New("Time.UnmarshalBinary: no data")
+	}
+
+	version := buf[0]
+	if version != timeBinaryVersionV1 && version != timeBinaryVersionV2 {
+		return errors.New("Time.UnmarshalBinary: unsupported version")
+	}
+
+	wantLen := /*version*/ 1 + /*sec*/ 8 + /*nsec*/ 4 + /*zone offset*/ 2
+	if version == timeBinaryVersionV2 {
+		wantLen++
+	}
+	if len(buf) != wantLen {
+		return errors.New("Time.UnmarshalBinary: invalid length")
+	}
+
+	buf = buf[1:]
+	sec := int64(buf[7]) | int64(buf[6])<<8 | int64(buf[5])<<16 | int64(buf[4])<<24 |
+		int64(buf[3])<<32 | int64(buf[2])<<40 | int64(buf[1])<<48 | int64(buf[0])<<56
+
+	buf = buf[8:]
+	nsec := int32(buf[3]) | int32(buf[2])<<8 | int32(buf[1])<<16 | int32(buf[0])<<24
+
+	buf = buf[4:]
+	offset := int(int16(buf[1])|int16(buf[0])<<8) * 60
+	if version == timeBinaryVersionV2 {
+		offset += int(buf[2])
+	}
+
+	*t = Time{}
+	t.wall = uint64(nsec)
+	t.ext = sec
+
+	if offset == -1*60 {
+		t.setLoc(&utcLoc)
+	} else if _, localoff, _, _, _ := Local.lookup(t.unixSec()); offset == localoff {
+		t.setLoc(Local)
+	} else {
+		t.setLoc(FixedZone("", offset))
+	}
+
+	return nil
+}
+
+// TODO(rsc): Remove GobEncoder, GobDecoder, MarshalJSON, UnmarshalJSON in Go 2.
+// The same semantics will be provided by the generic MarshalBinary, MarshalText,
+// UnmarshalBinary, UnmarshalText.
+
+// GobEncode implements the gob.GobEncoder interface.
+func (t Time) GobEncode() ([]byte, error) {
+	return t.MarshalBinary()
+}
+
+// GobDecode implements the gob.GobDecoder interface.
+func (t *Time) GobDecode(data []byte) error {
+	return t.UnmarshalBinary(data)
+}
+
+// MarshalJSON implements the json.Marshaler interface.
+// The time is a quoted string in the RFC 3339 format with sub-second precision.
+// If the timestamp cannot be represented as valid RFC 3339
+// (e.g., the year is out of range), then an error is reported.
+func (t Time) MarshalJSON() ([]byte, error) {
+	b := make([]byte, 0, len(RFC3339Nano)+len(`""`))
+	b = append(b, '"')
+	b, err := t.appendStrictRFC3339(b)
+	b = append(b, '"')
+	if err != nil {
+		return nil, errors.New("Time.MarshalJSON: " + err.Error())
+	}
+	return b, nil
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface.
+// The time must be a quoted string in the RFC 3339 format.
+func (t *Time) UnmarshalJSON(data []byte) error {
+	if string(data) == "null" {
+		return nil
+	}
+	// TODO(https://go.dev/issue/47353): Properly unescape a JSON string.
+	if len(data) < 2 || data[0] != '"' || data[len(data)-1] != '"' {
+		return errors.New("Time.UnmarshalJSON: input is not a JSON string")
+	}
+	data = data[len(`"`) : len(data)-len(`"`)]
+	var err error
+	*t, err = parseStrictRFC3339(data)
+	return err
+}
+
+// MarshalText implements the encoding.TextMarshaler interface.
+// The time is formatted in RFC 3339 format with sub-second precision.
+// If the timestamp cannot be represented as valid RFC 3339
+// (e.g., the year is out of range), then an error is reported.
+func (t Time) MarshalText() ([]byte, error) {
+	b := make([]byte, 0, len(RFC3339Nano))
+	b, err := t.appendStrictRFC3339(b)
+	if err != nil {
+		return nil, errors.New("Time.MarshalText: " + err.Error())
+	}
+	return b, nil
+}
+
+// UnmarshalText implements the encoding.TextUnmarshaler interface.
+// The time must be in the RFC 3339 format.
+func (t *Time) UnmarshalText(data []byte) error {
+	var err error
+	*t, err = parseStrictRFC3339(data)
+	return err
+}
+
+// Unix returns the local Time corresponding to the given Unix time,
+// sec seconds and nsec nanoseconds since January 1, 1970 UTC.
+// It is valid to pass nsec outside the range [0, 999999999].
+// Not all sec values have a corresponding time value. One such
+// value is 1<<63-1 (the largest int64 value).
+func Unix(sec int64, nsec int64) Time {
+	if nsec < 0 || nsec >= 1e9 {
+		n := nsec / 1e9
+		sec += n
+		nsec -= n * 1e9
+		if nsec < 0 {
+			nsec += 1e9
+			sec--
+		}
+	}
+	return unixTime(sec, int32(nsec))
+}
+
+// UnixMilli returns the local Time corresponding to the given Unix time,
+// msec milliseconds since January 1, 1970 UTC.
+func UnixMilli(msec int64) Time {
+	return Unix(msec/1e3, (msec%1e3)*1e6)
+}
+
+// UnixMicro returns the local Time corresponding to the given Unix time,
+// usec microseconds since January 1, 1970 UTC.
+func UnixMicro(usec int64) Time {
+	return Unix(usec/1e6, (usec%1e6)*1e3)
+}
+
+// IsDST reports whether the time in the configured location is in Daylight Savings Time.
+func (t Time) IsDST() bool {
+	_, _, _, _, isDST := t.loc.lookup(t.Unix())
+	return isDST
+}
+
+func isLeap(year int) bool {
+	return year%4 == 0 && (year%100 != 0 || year%400 == 0)
+}
+
+// norm returns nhi, nlo such that
+//
+//	hi * base + lo == nhi * base + nlo
+//	0 <= nlo < base
+func norm(hi, lo, base int) (nhi, nlo int) {
+	if lo < 0 {
+		n := (-lo-1)/base + 1
+		hi -= n
+		lo += n * base
+	}
+	if lo >= base {
+		n := lo / base
+		hi += n
+		lo -= n * base
+	}
+	return hi, lo
+}
+
+// Date returns the Time corresponding to
+//
+//	yyyy-mm-dd hh:mm:ss + nsec nanoseconds
+//
+// in the appropriate zone for that time in the given location.
+//
+// The month, day, hour, min, sec, and nsec values may be outside
+// their usual ranges and will be normalized during the conversion.
+// For example, October 32 converts to November 1.
+//
+// A daylight savings time transition skips or repeats times.
+// For example, in the United States, March 13, 2011 2:15am never occurred,
+// while November 6, 2011 1:15am occurred twice. In such cases, the
+// choice of time zone, and therefore the time, is not well-defined.
+// Date returns a time that is correct in one of the two zones involved
+// in the transition, but it does not guarantee which.
+//
+// Date panics if loc is nil.
+func Date(year int, month Month, day, hour, min, sec, nsec int, loc *Location) Time {
+	if loc == nil {
+		panic("time: missing Location in call to Date")
+	}
+
+	// Normalize month, overflowing into year.
+	m := int(month) - 1
+	year, m = norm(year, m, 12)
+	month = Month(m) + 1
+
+	// Normalize nsec, sec, min, hour, overflowing into day.
+	sec, nsec = norm(sec, nsec, 1e9)
+	min, sec = norm(min, sec, 60)
+	hour, min = norm(hour, min, 60)
+	day, hour = norm(day, hour, 24)
+
+	// Compute days since the absolute epoch.
+	d := daysSinceEpoch(year)
+
+	// Add in days before this month.
+	d += uint64(daysBefore[month-1])
+	if isLeap(year) && month >= March {
+		d++ // February 29
+	}
+
+	// Add in days before today.
+	d += uint64(day - 1)
+
+	// Add in time elapsed today.
+	abs := d * secondsPerDay
+	abs += uint64(hour*secondsPerHour + min*secondsPerMinute + sec)
+
+	unix := int64(abs) + (absoluteToInternal + internalToUnix)
+
+	// Look for zone offset for expected time, so we can adjust to UTC.
+	// The lookup function expects UTC, so first we pass unix in the
+	// hope that it will not be too close to a zone transition,
+	// and then adjust if it is.
+	_, offset, start, end, _ := loc.lookup(unix)
+	if offset != 0 {
+		utc := unix - int64(offset)
+		// If utc is valid for the time zone we found, then we have the right offset.
+		// If not, we get the correct offset by looking up utc in the location.
+		if utc < start || utc >= end {
+			_, offset, _, _, _ = loc.lookup(utc)
+		}
+		unix -= int64(offset)
+	}
+
+	t := unixTime(unix, int32(nsec))
+	t.setLoc(loc)
+	return t
+}
+
+// Truncate returns the result of rounding t down to a multiple of d (since the zero time).
+// If d <= 0, Truncate returns t stripped of any monotonic clock reading but otherwise unchanged.
+//
+// Truncate operates on the time as an absolute duration since the
+// zero time; it does not operate on the presentation form of the
+// time. Thus, Truncate(Hour) may return a time with a non-zero
+// minute, depending on the time's Location.
+func (t Time) Truncate(d Duration) Time {
+	t.stripMono()
+	if d <= 0 {
+		return t
+	}
+	_, r := div(t, d)
+	return t.Add(-r)
+}
+
+// Round returns the result of rounding t to the nearest multiple of d (since the zero time).
+// The rounding behavior for halfway values is to round up.
+// If d <= 0, Round returns t stripped of any monotonic clock reading but otherwise unchanged.
+//
+// Round operates on the time as an absolute duration since the
+// zero time; it does not operate on the presentation form of the
+// time. Thus, Round(Hour) may return a time with a non-zero
+// minute, depending on the time's Location.
+func (t Time) Round(d Duration) Time {
+	t.stripMono()
+	if d <= 0 {
+		return t
+	}
+	_, r := div(t, d)
+	if lessThanHalf(r, d) {
+		return t.Add(-r)
+	}
+	return t.Add(d - r)
+}
+
+// div divides t by d and returns the quotient parity and remainder.
+// We don't use the quotient parity anymore (round half up instead of round to even)
+// but it's still here in case we change our minds.
+func div(t Time, d Duration) (qmod2 int, r Duration) {
+	neg := false
+	nsec := t.nsec()
+	sec := t.sec()
+	if sec < 0 {
+		// Operate on absolute value.
+		neg = true
+		sec = -sec
+		nsec = -nsec
+		if nsec < 0 {
+			nsec += 1e9
+			sec-- // sec >= 1 before the -- so safe
+		}
+	}
+
+	switch {
+	// Special case: 2d divides 1 second.
+	case d < Second && Second%(d+d) == 0:
+		qmod2 = int(nsec/int32(d)) & 1
+		r = Duration(nsec % int32(d))
+
+	// Special case: d is a multiple of 1 second.
+	case d%Second == 0:
+		d1 := int64(d / Second)
+		qmod2 = int(sec/d1) & 1
+		r = Duration(sec%d1)*Second + Duration(nsec)
+
+	// General case.
+	// This could be faster if more cleverness were applied,
+	// but it's really only here to avoid special case restrictions in the API.
+	// No one will care about these cases.
+	default:
+		// Compute nanoseconds as 128-bit number.
+		sec := uint64(sec)
+		tmp := (sec >> 32) * 1e9
+		u1 := tmp >> 32
+		u0 := tmp << 32
+		tmp = (sec & 0xFFFFFFFF) * 1e9
+		u0x, u0 := u0, u0+tmp
+		if u0 < u0x {
+			u1++
+		}
+		u0x, u0 = u0, u0+uint64(nsec)
+		if u0 < u0x {
+			u1++
+		}
+
+		// Compute remainder by subtracting r<<k for decreasing k.
+		// Quotient parity is whether we subtract on last round.
+		d1 := uint64(d)
+		for d1>>63 != 1 {
+			d1 <<= 1
+		}
+		d0 := uint64(0)
+		for {
+			qmod2 = 0
+			if u1 > d1 || u1 == d1 && u0 >= d0 {
+				// subtract
+				qmod2 = 1
+				u0x, u0 = u0, u0-d0
+				if u0 > u0x {
+					u1--
+				}
+				u1 -= d1
+			}
+			if d1 == 0 && d0 == uint64(d) {
+				break
+			}
+			d0 >>= 1
+			d0 |= (d1 & 1) << 63
+			d1 >>= 1
+		}
+		r = Duration(u0)
+	}
+
+	if neg && r != 0 {
+		// If input was negative and not an exact multiple of d, we computed q, r such that
+		//	q*d + r = -t
+		// But the right answers are given by -(q-1), d-r:
+		//	q*d + r = -t
+		//	-q*d - r = t
+		//	-(q-1)*d + (d - r) = t
+		qmod2 ^= 1
+		r = d - r
+	}
+	return
+}
diff --git a/src/time/time_test.go b/src/time/time_test.go
new file mode 100644
index 0000000..3b30f80
--- /dev/null
+++ b/src/time/time_test.go
@@ -0,0 +1,1891 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"bytes"
+	"encoding/gob"
+	"encoding/json"
+	"fmt"
+	"math"
+	"math/big"
+	"math/rand"
+	"os"
+	"runtime"
+	"strings"
+	"sync"
+	"testing"
+	"testing/quick"
+	. "time"
+)
+
+// We should be in PST/PDT, but if the time zone files are missing we
+// won't be. The purpose of this test is to at least explain why some of
+// the subsequent tests fail.
+func TestZoneData(t *testing.T) {
+	lt := Now()
+	// PST is 8 hours west, PDT is 7 hours west. We could use the name but it's not unique.
+	if name, off := lt.Zone(); off != -8*60*60 && off != -7*60*60 {
+		t.Errorf("Unable to find US Pacific time zone data for testing; time zone is %q offset %d", name, off)
+		t.Error("Likely problem: the time zone files have not been installed.")
+	}
+}
+
+// parsedTime is the struct representing a parsed time value.
+type parsedTime struct {
+	Year                 int
+	Month                Month
+	Day                  int
+	Hour, Minute, Second int // 15:04:05 is 15, 4, 5.
+	Nanosecond           int // Fractional second.
+	Weekday              Weekday
+	ZoneOffset           int    // seconds east of UTC, e.g. -7*60*60 for -0700
+	Zone                 string // e.g., "MST"
+}
+
+type TimeTest struct {
+	seconds int64
+	golden  parsedTime
+}
+
+var utctests = []TimeTest{
+	{0, parsedTime{1970, January, 1, 0, 0, 0, 0, Thursday, 0, "UTC"}},
+	{1221681866, parsedTime{2008, September, 17, 20, 4, 26, 0, Wednesday, 0, "UTC"}},
+	{-1221681866, parsedTime{1931, April, 16, 3, 55, 34, 0, Thursday, 0, "UTC"}},
+	{-11644473600, parsedTime{1601, January, 1, 0, 0, 0, 0, Monday, 0, "UTC"}},
+	{599529660, parsedTime{1988, December, 31, 0, 1, 0, 0, Saturday, 0, "UTC"}},
+	{978220860, parsedTime{2000, December, 31, 0, 1, 0, 0, Sunday, 0, "UTC"}},
+}
+
+var nanoutctests = []TimeTest{
+	{0, parsedTime{1970, January, 1, 0, 0, 0, 1e8, Thursday, 0, "UTC"}},
+	{1221681866, parsedTime{2008, September, 17, 20, 4, 26, 2e8, Wednesday, 0, "UTC"}},
+}
+
+var localtests = []TimeTest{
+	{0, parsedTime{1969, December, 31, 16, 0, 0, 0, Wednesday, -8 * 60 * 60, "PST"}},
+	{1221681866, parsedTime{2008, September, 17, 13, 4, 26, 0, Wednesday, -7 * 60 * 60, "PDT"}},
+	{2159200800, parsedTime{2038, June, 3, 11, 0, 0, 0, Thursday, -7 * 60 * 60, "PDT"}},
+	{2152173599, parsedTime{2038, March, 14, 1, 59, 59, 0, Sunday, -8 * 60 * 60, "PST"}},
+	{2152173600, parsedTime{2038, March, 14, 3, 0, 0, 0, Sunday, -7 * 60 * 60, "PDT"}},
+	{2152173601, parsedTime{2038, March, 14, 3, 0, 1, 0, Sunday, -7 * 60 * 60, "PDT"}},
+	{2172733199, parsedTime{2038, November, 7, 1, 59, 59, 0, Sunday, -7 * 60 * 60, "PDT"}},
+	{2172733200, parsedTime{2038, November, 7, 1, 0, 0, 0, Sunday, -8 * 60 * 60, "PST"}},
+	{2172733201, parsedTime{2038, November, 7, 1, 0, 1, 0, Sunday, -8 * 60 * 60, "PST"}},
+}
+
+var nanolocaltests = []TimeTest{
+	{0, parsedTime{1969, December, 31, 16, 0, 0, 1e8, Wednesday, -8 * 60 * 60, "PST"}},
+	{1221681866, parsedTime{2008, September, 17, 13, 4, 26, 3e8, Wednesday, -7 * 60 * 60, "PDT"}},
+}
+
+func same(t Time, u *parsedTime) bool {
+	// Check aggregates.
+	year, month, day := t.Date()
+	hour, min, sec := t.Clock()
+	name, offset := t.Zone()
+	if year != u.Year || month != u.Month || day != u.Day ||
+		hour != u.Hour || min != u.Minute || sec != u.Second ||
+		name != u.Zone || offset != u.ZoneOffset {
+		return false
+	}
+	// Check individual entries.
+	return t.Year() == u.Year &&
+		t.Month() == u.Month &&
+		t.Day() == u.Day &&
+		t.Hour() == u.Hour &&
+		t.Minute() == u.Minute &&
+		t.Second() == u.Second &&
+		t.Nanosecond() == u.Nanosecond &&
+		t.Weekday() == u.Weekday
+}
+
+func TestSecondsToUTC(t *testing.T) {
+	for _, test := range utctests {
+		sec := test.seconds
+		golden := &test.golden
+		tm := Unix(sec, 0).UTC()
+		newsec := tm.Unix()
+		if newsec != sec {
+			t.Errorf("SecondsToUTC(%d).Seconds() = %d", sec, newsec)
+		}
+		if !same(tm, golden) {
+			t.Errorf("SecondsToUTC(%d):  // %#v", sec, tm)
+			t.Errorf("  want=%+v", *golden)
+			t.Errorf("  have=%v", tm.Format(RFC3339+" MST"))
+		}
+	}
+}
+
+func TestNanosecondsToUTC(t *testing.T) {
+	for _, test := range nanoutctests {
+		golden := &test.golden
+		nsec := test.seconds*1e9 + int64(golden.Nanosecond)
+		tm := Unix(0, nsec).UTC()
+		newnsec := tm.Unix()*1e9 + int64(tm.Nanosecond())
+		if newnsec != nsec {
+			t.Errorf("NanosecondsToUTC(%d).Nanoseconds() = %d", nsec, newnsec)
+		}
+		if !same(tm, golden) {
+			t.Errorf("NanosecondsToUTC(%d):", nsec)
+			t.Errorf("  want=%+v", *golden)
+			t.Errorf("  have=%+v", tm.Format(RFC3339+" MST"))
+		}
+	}
+}
+
+func TestSecondsToLocalTime(t *testing.T) {
+	for _, test := range localtests {
+		sec := test.seconds
+		golden := &test.golden
+		tm := Unix(sec, 0)
+		newsec := tm.Unix()
+		if newsec != sec {
+			t.Errorf("SecondsToLocalTime(%d).Seconds() = %d", sec, newsec)
+		}
+		if !same(tm, golden) {
+			t.Errorf("SecondsToLocalTime(%d):", sec)
+			t.Errorf("  want=%+v", *golden)
+			t.Errorf("  have=%+v", tm.Format(RFC3339+" MST"))
+		}
+	}
+}
+
+func TestNanosecondsToLocalTime(t *testing.T) {
+	for _, test := range nanolocaltests {
+		golden := &test.golden
+		nsec := test.seconds*1e9 + int64(golden.Nanosecond)
+		tm := Unix(0, nsec)
+		newnsec := tm.Unix()*1e9 + int64(tm.Nanosecond())
+		if newnsec != nsec {
+			t.Errorf("NanosecondsToLocalTime(%d).Seconds() = %d", nsec, newnsec)
+		}
+		if !same(tm, golden) {
+			t.Errorf("NanosecondsToLocalTime(%d):", nsec)
+			t.Errorf("  want=%+v", *golden)
+			t.Errorf("  have=%+v", tm.Format(RFC3339+" MST"))
+		}
+	}
+}
+
+func TestSecondsToUTCAndBack(t *testing.T) {
+	f := func(sec int64) bool { return Unix(sec, 0).UTC().Unix() == sec }
+	f32 := func(sec int32) bool { return f(int64(sec)) }
+	cfg := &quick.Config{MaxCount: 10000}
+
+	// Try a reasonable date first, then the huge ones.
+	if err := quick.Check(f32, cfg); err != nil {
+		t.Fatal(err)
+	}
+	if err := quick.Check(f, cfg); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestNanosecondsToUTCAndBack(t *testing.T) {
+	f := func(nsec int64) bool {
+		t := Unix(0, nsec).UTC()
+		ns := t.Unix()*1e9 + int64(t.Nanosecond())
+		return ns == nsec
+	}
+	f32 := func(nsec int32) bool { return f(int64(nsec)) }
+	cfg := &quick.Config{MaxCount: 10000}
+
+	// Try a small date first, then the large ones. (The span is only a few hundred years
+	// for nanoseconds in an int64.)
+	if err := quick.Check(f32, cfg); err != nil {
+		t.Fatal(err)
+	}
+	if err := quick.Check(f, cfg); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestUnixMilli(t *testing.T) {
+	f := func(msec int64) bool {
+		t := UnixMilli(msec)
+		return t.UnixMilli() == msec
+	}
+	cfg := &quick.Config{MaxCount: 10000}
+	if err := quick.Check(f, cfg); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestUnixMicro(t *testing.T) {
+	f := func(usec int64) bool {
+		t := UnixMicro(usec)
+		return t.UnixMicro() == usec
+	}
+	cfg := &quick.Config{MaxCount: 10000}
+	if err := quick.Check(f, cfg); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// The time routines provide no way to get absolute time
+// (seconds since zero), but we need it to compute the right
+// answer for bizarre roundings like "to the nearest 3 ns".
+// Compute as t - year1 = (t - 1970) + (1970 - 2001) + (2001 - 1).
+// t - 1970 is returned by Unix and Nanosecond.
+// 1970 - 2001 is -(31*365+8)*86400 = -978307200 seconds.
+// 2001 - 1 is 2000*365.2425*86400 = 63113904000 seconds.
+const unixToZero = -978307200 + 63113904000
+
+// abs returns the absolute time stored in t, as seconds and nanoseconds.
+func abs(t Time) (sec, nsec int64) {
+	unix := t.Unix()
+	nano := t.Nanosecond()
+	return unix + unixToZero, int64(nano)
+}
+
+// absString returns abs as a decimal string.
+func absString(t Time) string {
+	sec, nsec := abs(t)
+	if sec < 0 {
+		sec = -sec
+		nsec = -nsec
+		if nsec < 0 {
+			nsec += 1e9
+			sec--
+		}
+		return fmt.Sprintf("-%d%09d", sec, nsec)
+	}
+	return fmt.Sprintf("%d%09d", sec, nsec)
+}
+
+var truncateRoundTests = []struct {
+	t Time
+	d Duration
+}{
+	{Date(-1, January, 1, 12, 15, 30, 5e8, UTC), 3},
+	{Date(-1, January, 1, 12, 15, 31, 5e8, UTC), 3},
+	{Date(2012, January, 1, 12, 15, 30, 5e8, UTC), Second},
+	{Date(2012, January, 1, 12, 15, 31, 5e8, UTC), Second},
+	{Unix(-19012425939, 649146258), 7435029458905025217}, // 5.8*d rounds to 6*d, but .8*d+.8*d < 0 < d
+}
+
+func TestTruncateRound(t *testing.T) {
+	var (
+		bsec  = new(big.Int)
+		bnsec = new(big.Int)
+		bd    = new(big.Int)
+		bt    = new(big.Int)
+		br    = new(big.Int)
+		bq    = new(big.Int)
+		b1e9  = new(big.Int)
+	)
+
+	b1e9.SetInt64(1e9)
+
+	testOne := func(ti, tns, di int64) bool {
+		t.Helper()
+
+		t0 := Unix(ti, int64(tns)).UTC()
+		d := Duration(di)
+		if d < 0 {
+			d = -d
+		}
+		if d <= 0 {
+			d = 1
+		}
+
+		// Compute bt = absolute nanoseconds.
+		sec, nsec := abs(t0)
+		bsec.SetInt64(sec)
+		bnsec.SetInt64(nsec)
+		bt.Mul(bsec, b1e9)
+		bt.Add(bt, bnsec)
+
+		// Compute quotient and remainder mod d.
+		bd.SetInt64(int64(d))
+		bq.DivMod(bt, bd, br)
+
+		// To truncate, subtract remainder.
+		// br is < d, so it fits in an int64.
+		r := br.Int64()
+		t1 := t0.Add(-Duration(r))
+
+		// Check that time.Truncate works.
+		if trunc := t0.Truncate(d); trunc != t1 {
+			t.Errorf("Time.Truncate(%s, %s) = %s, want %s\n"+
+				"%v trunc %v =\n%v want\n%v",
+				t0.Format(RFC3339Nano), d, trunc, t1.Format(RFC3339Nano),
+				absString(t0), int64(d), absString(trunc), absString(t1))
+			return false
+		}
+
+		// To round, add d back if remainder r > d/2 or r == exactly d/2.
+		// The commented out code would round half to even instead of up,
+		// but that makes it time-zone dependent, which is a bit strange.
+		if r > int64(d)/2 || r+r == int64(d) /*&& bq.Bit(0) == 1*/ {
+			t1 = t1.Add(Duration(d))
+		}
+
+		// Check that time.Round works.
+		if rnd := t0.Round(d); rnd != t1 {
+			t.Errorf("Time.Round(%s, %s) = %s, want %s\n"+
+				"%v round %v =\n%v want\n%v",
+				t0.Format(RFC3339Nano), d, rnd, t1.Format(RFC3339Nano),
+				absString(t0), int64(d), absString(rnd), absString(t1))
+			return false
+		}
+		return true
+	}
+
+	// manual test cases
+	for _, tt := range truncateRoundTests {
+		testOne(tt.t.Unix(), int64(tt.t.Nanosecond()), int64(tt.d))
+	}
+
+	// exhaustive near 0
+	for i := 0; i < 100; i++ {
+		for j := 1; j < 100; j++ {
+			testOne(unixToZero, int64(i), int64(j))
+			testOne(unixToZero, -int64(i), int64(j))
+			if t.Failed() {
+				return
+			}
+		}
+	}
+
+	if t.Failed() {
+		return
+	}
+
+	// randomly generated test cases
+	cfg := &quick.Config{MaxCount: 100000}
+	if testing.Short() {
+		cfg.MaxCount = 1000
+	}
+
+	// divisors of Second
+	f1 := func(ti int64, tns int32, logdi int32) bool {
+		d := Duration(1)
+		a, b := uint(logdi%9), (logdi>>16)%9
+		d <<= a
+		for i := 0; i < int(b); i++ {
+			d *= 5
+		}
+
+		// Make room for unix ↔ internal conversion.
+		// We don't care about behavior too close to ± 2^63 Unix seconds.
+		// It is full of wraparounds but will never happen in a reasonable program.
+		// (Or maybe not? See go.dev/issue/20678. In any event, they're not handled today.)
+		ti >>= 1
+
+		return testOne(ti, int64(tns), int64(d))
+	}
+	quick.Check(f1, cfg)
+
+	// multiples of Second
+	f2 := func(ti int64, tns int32, di int32) bool {
+		d := Duration(di) * Second
+		if d < 0 {
+			d = -d
+		}
+		ti >>= 1 // see comment in f1
+		return testOne(ti, int64(tns), int64(d))
+	}
+	quick.Check(f2, cfg)
+
+	// halfway cases
+	f3 := func(tns, di int64) bool {
+		di &= 0xfffffffe
+		if di == 0 {
+			di = 2
+		}
+		tns -= tns % di
+		if tns < 0 {
+			tns += di / 2
+		} else {
+			tns -= di / 2
+		}
+		return testOne(0, tns, di)
+	}
+	quick.Check(f3, cfg)
+
+	// full generality
+	f4 := func(ti int64, tns int32, di int64) bool {
+		ti >>= 1 // see comment in f1
+		return testOne(ti, int64(tns), di)
+	}
+	quick.Check(f4, cfg)
+}
+
+type ISOWeekTest struct {
+	year       int // year
+	month, day int // month and day
+	yex        int // expected year
+	wex        int // expected week
+}
+
+var isoWeekTests = []ISOWeekTest{
+	{1981, 1, 1, 1981, 1}, {1982, 1, 1, 1981, 53}, {1983, 1, 1, 1982, 52},
+	{1984, 1, 1, 1983, 52}, {1985, 1, 1, 1985, 1}, {1986, 1, 1, 1986, 1},
+	{1987, 1, 1, 1987, 1}, {1988, 1, 1, 1987, 53}, {1989, 1, 1, 1988, 52},
+	{1990, 1, 1, 1990, 1}, {1991, 1, 1, 1991, 1}, {1992, 1, 1, 1992, 1},
+	{1993, 1, 1, 1992, 53}, {1994, 1, 1, 1993, 52}, {1995, 1, 2, 1995, 1},
+	{1996, 1, 1, 1996, 1}, {1996, 1, 7, 1996, 1}, {1996, 1, 8, 1996, 2},
+	{1997, 1, 1, 1997, 1}, {1998, 1, 1, 1998, 1}, {1999, 1, 1, 1998, 53},
+	{2000, 1, 1, 1999, 52}, {2001, 1, 1, 2001, 1}, {2002, 1, 1, 2002, 1},
+	{2003, 1, 1, 2003, 1}, {2004, 1, 1, 2004, 1}, {2005, 1, 1, 2004, 53},
+	{2006, 1, 1, 2005, 52}, {2007, 1, 1, 2007, 1}, {2008, 1, 1, 2008, 1},
+	{2009, 1, 1, 2009, 1}, {2010, 1, 1, 2009, 53}, {2010, 1, 1, 2009, 53},
+	{2011, 1, 1, 2010, 52}, {2011, 1, 2, 2010, 52}, {2011, 1, 3, 2011, 1},
+	{2011, 1, 4, 2011, 1}, {2011, 1, 5, 2011, 1}, {2011, 1, 6, 2011, 1},
+	{2011, 1, 7, 2011, 1}, {2011, 1, 8, 2011, 1}, {2011, 1, 9, 2011, 1},
+	{2011, 1, 10, 2011, 2}, {2011, 1, 11, 2011, 2}, {2011, 6, 12, 2011, 23},
+	{2011, 6, 13, 2011, 24}, {2011, 12, 25, 2011, 51}, {2011, 12, 26, 2011, 52},
+	{2011, 12, 27, 2011, 52}, {2011, 12, 28, 2011, 52}, {2011, 12, 29, 2011, 52},
+	{2011, 12, 30, 2011, 52}, {2011, 12, 31, 2011, 52}, {1995, 1, 1, 1994, 52},
+	{2012, 1, 1, 2011, 52}, {2012, 1, 2, 2012, 1}, {2012, 1, 8, 2012, 1},
+	{2012, 1, 9, 2012, 2}, {2012, 12, 23, 2012, 51}, {2012, 12, 24, 2012, 52},
+	{2012, 12, 30, 2012, 52}, {2012, 12, 31, 2013, 1}, {2013, 1, 1, 2013, 1},
+	{2013, 1, 6, 2013, 1}, {2013, 1, 7, 2013, 2}, {2013, 12, 22, 2013, 51},
+	{2013, 12, 23, 2013, 52}, {2013, 12, 29, 2013, 52}, {2013, 12, 30, 2014, 1},
+	{2014, 1, 1, 2014, 1}, {2014, 1, 5, 2014, 1}, {2014, 1, 6, 2014, 2},
+	{2015, 1, 1, 2015, 1}, {2016, 1, 1, 2015, 53}, {2017, 1, 1, 2016, 52},
+	{2018, 1, 1, 2018, 1}, {2019, 1, 1, 2019, 1}, {2020, 1, 1, 2020, 1},
+	{2021, 1, 1, 2020, 53}, {2022, 1, 1, 2021, 52}, {2023, 1, 1, 2022, 52},
+	{2024, 1, 1, 2024, 1}, {2025, 1, 1, 2025, 1}, {2026, 1, 1, 2026, 1},
+	{2027, 1, 1, 2026, 53}, {2028, 1, 1, 2027, 52}, {2029, 1, 1, 2029, 1},
+	{2030, 1, 1, 2030, 1}, {2031, 1, 1, 2031, 1}, {2032, 1, 1, 2032, 1},
+	{2033, 1, 1, 2032, 53}, {2034, 1, 1, 2033, 52}, {2035, 1, 1, 2035, 1},
+	{2036, 1, 1, 2036, 1}, {2037, 1, 1, 2037, 1}, {2038, 1, 1, 2037, 53},
+	{2039, 1, 1, 2038, 52}, {2040, 1, 1, 2039, 52},
+}
+
+func TestISOWeek(t *testing.T) {
+	// Selected dates and corner cases
+	for _, wt := range isoWeekTests {
+		dt := Date(wt.year, Month(wt.month), wt.day, 0, 0, 0, 0, UTC)
+		y, w := dt.ISOWeek()
+		if w != wt.wex || y != wt.yex {
+			t.Errorf("got %d/%d; expected %d/%d for %d-%02d-%02d",
+				y, w, wt.yex, wt.wex, wt.year, wt.month, wt.day)
+		}
+	}
+
+	// The only real invariant: Jan 04 is in week 1
+	for year := 1950; year < 2100; year++ {
+		if y, w := Date(year, January, 4, 0, 0, 0, 0, UTC).ISOWeek(); y != year || w != 1 {
+			t.Errorf("got %d/%d; expected %d/1 for Jan 04", y, w, year)
+		}
+	}
+}
+
+type YearDayTest struct {
+	year, month, day int
+	yday             int
+}
+
+// Test YearDay in several different scenarios
+// and corner cases
+var yearDayTests = []YearDayTest{
+	// Non-leap-year tests
+	{2007, 1, 1, 1},
+	{2007, 1, 15, 15},
+	{2007, 2, 1, 32},
+	{2007, 2, 15, 46},
+	{2007, 3, 1, 60},
+	{2007, 3, 15, 74},
+	{2007, 4, 1, 91},
+	{2007, 12, 31, 365},
+
+	// Leap-year tests
+	{2008, 1, 1, 1},
+	{2008, 1, 15, 15},
+	{2008, 2, 1, 32},
+	{2008, 2, 15, 46},
+	{2008, 3, 1, 61},
+	{2008, 3, 15, 75},
+	{2008, 4, 1, 92},
+	{2008, 12, 31, 366},
+
+	// Looks like leap-year (but isn't) tests
+	{1900, 1, 1, 1},
+	{1900, 1, 15, 15},
+	{1900, 2, 1, 32},
+	{1900, 2, 15, 46},
+	{1900, 3, 1, 60},
+	{1900, 3, 15, 74},
+	{1900, 4, 1, 91},
+	{1900, 12, 31, 365},
+
+	// Year one tests (non-leap)
+	{1, 1, 1, 1},
+	{1, 1, 15, 15},
+	{1, 2, 1, 32},
+	{1, 2, 15, 46},
+	{1, 3, 1, 60},
+	{1, 3, 15, 74},
+	{1, 4, 1, 91},
+	{1, 12, 31, 365},
+
+	// Year minus one tests (non-leap)
+	{-1, 1, 1, 1},
+	{-1, 1, 15, 15},
+	{-1, 2, 1, 32},
+	{-1, 2, 15, 46},
+	{-1, 3, 1, 60},
+	{-1, 3, 15, 74},
+	{-1, 4, 1, 91},
+	{-1, 12, 31, 365},
+
+	// 400 BC tests (leap-year)
+	{-400, 1, 1, 1},
+	{-400, 1, 15, 15},
+	{-400, 2, 1, 32},
+	{-400, 2, 15, 46},
+	{-400, 3, 1, 61},
+	{-400, 3, 15, 75},
+	{-400, 4, 1, 92},
+	{-400, 12, 31, 366},
+
+	// Special Cases
+
+	// Gregorian calendar change (no effect)
+	{1582, 10, 4, 277},
+	{1582, 10, 15, 288},
+}
+
+// Check to see if YearDay is location sensitive
+var yearDayLocations = []*Location{
+	FixedZone("UTC-8", -8*60*60),
+	FixedZone("UTC-4", -4*60*60),
+	UTC,
+	FixedZone("UTC+4", 4*60*60),
+	FixedZone("UTC+8", 8*60*60),
+}
+
+func TestYearDay(t *testing.T) {
+	for i, loc := range yearDayLocations {
+		for _, ydt := range yearDayTests {
+			dt := Date(ydt.year, Month(ydt.month), ydt.day, 0, 0, 0, 0, loc)
+			yday := dt.YearDay()
+			if yday != ydt.yday {
+				t.Errorf("Date(%d-%02d-%02d in %v).YearDay() = %d, want %d",
+					ydt.year, ydt.month, ydt.day, loc, yday, ydt.yday)
+				continue
+			}
+
+			if ydt.year < 0 || ydt.year > 9999 {
+				continue
+			}
+			f := fmt.Sprintf("%04d-%02d-%02d %03d %+.2d00",
+				ydt.year, ydt.month, ydt.day, ydt.yday, (i-2)*4)
+			dt1, err := Parse("2006-01-02 002 -0700", f)
+			if err != nil {
+				t.Errorf(`Parse("2006-01-02 002 -0700", %q): %v`, f, err)
+				continue
+			}
+			if !dt1.Equal(dt) {
+				t.Errorf(`Parse("2006-01-02 002 -0700", %q) = %v, want %v`, f, dt1, dt)
+			}
+		}
+	}
+}
+
+var durationTests = []struct {
+	str string
+	d   Duration
+}{
+	{"0s", 0},
+	{"1ns", 1 * Nanosecond},
+	{"1.1µs", 1100 * Nanosecond},
+	{"2.2ms", 2200 * Microsecond},
+	{"3.3s", 3300 * Millisecond},
+	{"4m5s", 4*Minute + 5*Second},
+	{"4m5.001s", 4*Minute + 5001*Millisecond},
+	{"5h6m7.001s", 5*Hour + 6*Minute + 7001*Millisecond},
+	{"8m0.000000001s", 8*Minute + 1*Nanosecond},
+	{"2562047h47m16.854775807s", 1<<63 - 1},
+	{"-2562047h47m16.854775808s", -1 << 63},
+}
+
+func TestDurationString(t *testing.T) {
+	for _, tt := range durationTests {
+		if str := tt.d.String(); str != tt.str {
+			t.Errorf("Duration(%d).String() = %s, want %s", int64(tt.d), str, tt.str)
+		}
+		if tt.d > 0 {
+			if str := (-tt.d).String(); str != "-"+tt.str {
+				t.Errorf("Duration(%d).String() = %s, want %s", int64(-tt.d), str, "-"+tt.str)
+			}
+		}
+	}
+}
+
+var dateTests = []struct {
+	year, month, day, hour, min, sec, nsec int
+	z                                      *Location
+	unix                                   int64
+}{
+	{2011, 11, 6, 1, 0, 0, 0, Local, 1320566400},   // 1:00:00 PDT
+	{2011, 11, 6, 1, 59, 59, 0, Local, 1320569999}, // 1:59:59 PDT
+	{2011, 11, 6, 2, 0, 0, 0, Local, 1320573600},   // 2:00:00 PST
+
+	{2011, 3, 13, 1, 0, 0, 0, Local, 1300006800},   // 1:00:00 PST
+	{2011, 3, 13, 1, 59, 59, 0, Local, 1300010399}, // 1:59:59 PST
+	{2011, 3, 13, 3, 0, 0, 0, Local, 1300010400},   // 3:00:00 PDT
+	{2011, 3, 13, 2, 30, 0, 0, Local, 1300008600},  // 2:30:00 PDT ≡ 1:30 PST
+	{2012, 12, 24, 0, 0, 0, 0, Local, 1356336000},  // Leap year
+
+	// Many names for Fri Nov 18 7:56:35 PST 2011
+	{2011, 11, 18, 7, 56, 35, 0, Local, 1321631795},                 // Nov 18 7:56:35
+	{2011, 11, 19, -17, 56, 35, 0, Local, 1321631795},               // Nov 19 -17:56:35
+	{2011, 11, 17, 31, 56, 35, 0, Local, 1321631795},                // Nov 17 31:56:35
+	{2011, 11, 18, 6, 116, 35, 0, Local, 1321631795},                // Nov 18 6:116:35
+	{2011, 10, 49, 7, 56, 35, 0, Local, 1321631795},                 // Oct 49 7:56:35
+	{2011, 11, 18, 7, 55, 95, 0, Local, 1321631795},                 // Nov 18 7:55:95
+	{2011, 11, 18, 7, 56, 34, 1e9, Local, 1321631795},               // Nov 18 7:56:34 + 10⁹ns
+	{2011, 12, -12, 7, 56, 35, 0, Local, 1321631795},                // Dec -21 7:56:35
+	{2012, 1, -43, 7, 56, 35, 0, Local, 1321631795},                 // Jan -52 7:56:35 2012
+	{2012, int(January - 2), 18, 7, 56, 35, 0, Local, 1321631795},   // (Jan-2) 18 7:56:35 2012
+	{2010, int(December + 11), 18, 7, 56, 35, 0, Local, 1321631795}, // (Dec+11) 18 7:56:35 2010
+}
+
+func TestDate(t *testing.T) {
+	for _, tt := range dateTests {
+		time := Date(tt.year, Month(tt.month), tt.day, tt.hour, tt.min, tt.sec, tt.nsec, tt.z)
+		want := Unix(tt.unix, 0)
+		if !time.Equal(want) {
+			t.Errorf("Date(%d, %d, %d, %d, %d, %d, %d, %s) = %v, want %v",
+				tt.year, tt.month, tt.day, tt.hour, tt.min, tt.sec, tt.nsec, tt.z,
+				time, want)
+		}
+	}
+}
+
+// Several ways of getting from
+// Fri Nov 18 7:56:35 PST 2011
+// to
+// Thu Mar 19 7:56:35 PST 2016
+var addDateTests = []struct {
+	years, months, days int
+}{
+	{4, 4, 1},
+	{3, 16, 1},
+	{3, 15, 30},
+	{5, -6, -18 - 30 - 12},
+}
+
+func TestAddDate(t *testing.T) {
+	t0 := Date(2011, 11, 18, 7, 56, 35, 0, UTC)
+	t1 := Date(2016, 3, 19, 7, 56, 35, 0, UTC)
+	for _, at := range addDateTests {
+		time := t0.AddDate(at.years, at.months, at.days)
+		if !time.Equal(t1) {
+			t.Errorf("AddDate(%d, %d, %d) = %v, want %v",
+				at.years, at.months, at.days,
+				time, t1)
+		}
+	}
+}
+
+var daysInTests = []struct {
+	year, month, di int
+}{
+	{2011, 1, 31},  // January, first month, 31 days
+	{2011, 2, 28},  // February, non-leap year, 28 days
+	{2012, 2, 29},  // February, leap year, 29 days
+	{2011, 6, 30},  // June, 30 days
+	{2011, 12, 31}, // December, last month, 31 days
+}
+
+func TestDaysIn(t *testing.T) {
+	// The daysIn function is not exported.
+	// Test the daysIn function via the `var DaysIn = daysIn`
+	// statement in the internal_test.go file.
+	for _, tt := range daysInTests {
+		di := DaysIn(Month(tt.month), tt.year)
+		if di != tt.di {
+			t.Errorf("got %d; expected %d for %d-%02d",
+				di, tt.di, tt.year, tt.month)
+		}
+	}
+}
+
+func TestAddToExactSecond(t *testing.T) {
+	// Add an amount to the current time to round it up to the next exact second.
+	// This test checks that the nsec field still lies within the range [0, 999999999].
+	t1 := Now()
+	t2 := t1.Add(Second - Duration(t1.Nanosecond()))
+	sec := (t1.Second() + 1) % 60
+	if t2.Second() != sec || t2.Nanosecond() != 0 {
+		t.Errorf("sec = %d, nsec = %d, want sec = %d, nsec = 0", t2.Second(), t2.Nanosecond(), sec)
+	}
+}
+
+func equalTimeAndZone(a, b Time) bool {
+	aname, aoffset := a.Zone()
+	bname, boffset := b.Zone()
+	return a.Equal(b) && aoffset == boffset && aname == bname
+}
+
+var gobTests = []Time{
+	Date(0, 1, 2, 3, 4, 5, 6, UTC),
+	Date(7, 8, 9, 10, 11, 12, 13, FixedZone("", 0)),
+	Unix(81985467080890095, 0x76543210), // Time.sec: 0x0123456789ABCDEF
+	{},                                  // nil location
+	Date(1, 2, 3, 4, 5, 6, 7, FixedZone("", 32767*60)),
+	Date(1, 2, 3, 4, 5, 6, 7, FixedZone("", -32768*60)),
+}
+
+func TestTimeGob(t *testing.T) {
+	var b bytes.Buffer
+	enc := gob.NewEncoder(&b)
+	dec := gob.NewDecoder(&b)
+	for _, tt := range gobTests {
+		var gobtt Time
+		if err := enc.Encode(&tt); err != nil {
+			t.Errorf("%v gob Encode error = %q, want nil", tt, err)
+		} else if err := dec.Decode(&gobtt); err != nil {
+			t.Errorf("%v gob Decode error = %q, want nil", tt, err)
+		} else if !equalTimeAndZone(gobtt, tt) {
+			t.Errorf("Decoded time = %v, want %v", gobtt, tt)
+		}
+		b.Reset()
+	}
+}
+
+var invalidEncodingTests = []struct {
+	bytes []byte
+	want  string
+}{
+	{[]byte{}, "Time.UnmarshalBinary: no data"},
+	{[]byte{0, 2, 3}, "Time.UnmarshalBinary: unsupported version"},
+	{[]byte{1, 2, 3}, "Time.UnmarshalBinary: invalid length"},
+}
+
+func TestInvalidTimeGob(t *testing.T) {
+	for _, tt := range invalidEncodingTests {
+		var ignored Time
+		err := ignored.GobDecode(tt.bytes)
+		if err == nil || err.Error() != tt.want {
+			t.Errorf("time.GobDecode(%#v) error = %v, want %v", tt.bytes, err, tt.want)
+		}
+		err = ignored.UnmarshalBinary(tt.bytes)
+		if err == nil || err.Error() != tt.want {
+			t.Errorf("time.UnmarshalBinary(%#v) error = %v, want %v", tt.bytes, err, tt.want)
+		}
+	}
+}
+
+var notEncodableTimes = []struct {
+	time Time
+	want string
+}{
+	{Date(0, 1, 2, 3, 4, 5, 6, FixedZone("", -1*60)), "Time.MarshalBinary: unexpected zone offset"},
+	{Date(0, 1, 2, 3, 4, 5, 6, FixedZone("", -32769*60)), "Time.MarshalBinary: unexpected zone offset"},
+	{Date(0, 1, 2, 3, 4, 5, 6, FixedZone("", 32768*60)), "Time.MarshalBinary: unexpected zone offset"},
+}
+
+func TestNotGobEncodableTime(t *testing.T) {
+	for _, tt := range notEncodableTimes {
+		_, err := tt.time.GobEncode()
+		if err == nil || err.Error() != tt.want {
+			t.Errorf("%v GobEncode error = %v, want %v", tt.time, err, tt.want)
+		}
+		_, err = tt.time.MarshalBinary()
+		if err == nil || err.Error() != tt.want {
+			t.Errorf("%v MarshalBinary error = %v, want %v", tt.time, err, tt.want)
+		}
+	}
+}
+
+var jsonTests = []struct {
+	time Time
+	json string
+}{
+	{Date(9999, 4, 12, 23, 20, 50, 520*1e6, UTC), `"9999-04-12T23:20:50.52Z"`},
+	{Date(1996, 12, 19, 16, 39, 57, 0, Local), `"1996-12-19T16:39:57-08:00"`},
+	{Date(0, 1, 1, 0, 0, 0, 1, FixedZone("", 1*60)), `"0000-01-01T00:00:00.000000001+00:01"`},
+	{Date(2020, 1, 1, 0, 0, 0, 0, FixedZone("", 23*60*60+59*60)), `"2020-01-01T00:00:00+23:59"`},
+}
+
+func TestTimeJSON(t *testing.T) {
+	for _, tt := range jsonTests {
+		var jsonTime Time
+
+		if jsonBytes, err := json.Marshal(tt.time); err != nil {
+			t.Errorf("%v json.Marshal error = %v, want nil", tt.time, err)
+		} else if string(jsonBytes) != tt.json {
+			t.Errorf("%v JSON = %#q, want %#q", tt.time, string(jsonBytes), tt.json)
+		} else if err = json.Unmarshal(jsonBytes, &jsonTime); err != nil {
+			t.Errorf("%v json.Unmarshal error = %v, want nil", tt.time, err)
+		} else if !equalTimeAndZone(jsonTime, tt.time) {
+			t.Errorf("Unmarshaled time = %v, want %v", jsonTime, tt.time)
+		}
+	}
+}
+
+func TestUnmarshalInvalidTimes(t *testing.T) {
+	tests := []struct {
+		in   string
+		want string
+	}{
+		{`{}`, "Time.UnmarshalJSON: input is not a JSON string"},
+		{`[]`, "Time.UnmarshalJSON: input is not a JSON string"},
+		{`"2000-01-01T1:12:34Z"`, `<nil>`},
+		{`"2000-01-01T00:00:00,000Z"`, `<nil>`},
+		{`"2000-01-01T00:00:00+24:00"`, `<nil>`},
+		{`"2000-01-01T00:00:00+00:60"`, `<nil>`},
+		{`"2000-01-01T00:00:00+123:45"`, `parsing time "2000-01-01T00:00:00+123:45" as "2006-01-02T15:04:05Z07:00": cannot parse "+123:45" as "Z07:00"`},
+	}
+
+	for _, tt := range tests {
+		var ts Time
+
+		want := tt.want
+		err := json.Unmarshal([]byte(tt.in), &ts)
+		if fmt.Sprint(err) != want {
+			t.Errorf("Time.UnmarshalJSON(%s) = %v, want %v", tt.in, err, want)
+		}
+
+		if strings.HasPrefix(tt.in, `"`) && strings.HasSuffix(tt.in, `"`) {
+			err = ts.UnmarshalText([]byte(strings.Trim(tt.in, `"`)))
+			if fmt.Sprint(err) != want {
+				t.Errorf("Time.UnmarshalText(%s) = %v, want %v", tt.in, err, want)
+			}
+		}
+	}
+}
+
+func TestMarshalInvalidTimes(t *testing.T) {
+	tests := []struct {
+		time Time
+		want string
+	}{
+		{Date(10000, 1, 1, 0, 0, 0, 0, UTC), "Time.MarshalJSON: year outside of range [0,9999]"},
+		{Date(-998, 1, 1, 0, 0, 0, 0, UTC).Add(-Second), "Time.MarshalJSON: year outside of range [0,9999]"},
+		{Date(0, 1, 1, 0, 0, 0, 0, UTC).Add(-Nanosecond), "Time.MarshalJSON: year outside of range [0,9999]"},
+		{Date(2020, 1, 1, 0, 0, 0, 0, FixedZone("", 24*60*60)), "Time.MarshalJSON: timezone hour outside of range [0,23]"},
+		{Date(2020, 1, 1, 0, 0, 0, 0, FixedZone("", 123*60*60)), "Time.MarshalJSON: timezone hour outside of range [0,23]"},
+	}
+
+	for _, tt := range tests {
+		want := tt.want
+		b, err := tt.time.MarshalJSON()
+		switch {
+		case b != nil:
+			t.Errorf("(%v).MarshalText() = %q, want nil", tt.time, b)
+		case err == nil || err.Error() != want:
+			t.Errorf("(%v).MarshalJSON() error = %v, want %v", tt.time, err, want)
+		}
+
+		want = strings.ReplaceAll(tt.want, "JSON", "Text")
+		b, err = tt.time.MarshalText()
+		switch {
+		case b != nil:
+			t.Errorf("(%v).MarshalText() = %q, want nil", tt.time, b)
+		case err == nil || err.Error() != want:
+			t.Errorf("(%v).MarshalText() error = %v, want %v", tt.time, err, want)
+		}
+	}
+}
+
+var parseDurationTests = []struct {
+	in   string
+	want Duration
+}{
+	// simple
+	{"0", 0},
+	{"5s", 5 * Second},
+	{"30s", 30 * Second},
+	{"1478s", 1478 * Second},
+	// sign
+	{"-5s", -5 * Second},
+	{"+5s", 5 * Second},
+	{"-0", 0},
+	{"+0", 0},
+	// decimal
+	{"5.0s", 5 * Second},
+	{"5.6s", 5*Second + 600*Millisecond},
+	{"5.s", 5 * Second},
+	{".5s", 500 * Millisecond},
+	{"1.0s", 1 * Second},
+	{"1.00s", 1 * Second},
+	{"1.004s", 1*Second + 4*Millisecond},
+	{"1.0040s", 1*Second + 4*Millisecond},
+	{"100.00100s", 100*Second + 1*Millisecond},
+	// different units
+	{"10ns", 10 * Nanosecond},
+	{"11us", 11 * Microsecond},
+	{"12µs", 12 * Microsecond}, // U+00B5
+	{"12μs", 12 * Microsecond}, // U+03BC
+	{"13ms", 13 * Millisecond},
+	{"14s", 14 * Second},
+	{"15m", 15 * Minute},
+	{"16h", 16 * Hour},
+	// composite durations
+	{"3h30m", 3*Hour + 30*Minute},
+	{"10.5s4m", 4*Minute + 10*Second + 500*Millisecond},
+	{"-2m3.4s", -(2*Minute + 3*Second + 400*Millisecond)},
+	{"1h2m3s4ms5us6ns", 1*Hour + 2*Minute + 3*Second + 4*Millisecond + 5*Microsecond + 6*Nanosecond},
+	{"39h9m14.425s", 39*Hour + 9*Minute + 14*Second + 425*Millisecond},
+	// large value
+	{"52763797000ns", 52763797000 * Nanosecond},
+	// more than 9 digits after decimal point, see https://golang.org/issue/6617
+	{"0.3333333333333333333h", 20 * Minute},
+	// 9007199254740993 = 1<<53+1 cannot be stored precisely in a float64
+	{"9007199254740993ns", (1<<53 + 1) * Nanosecond},
+	// largest duration that can be represented by int64 in nanoseconds
+	{"9223372036854775807ns", (1<<63 - 1) * Nanosecond},
+	{"9223372036854775.807us", (1<<63 - 1) * Nanosecond},
+	{"9223372036s854ms775us807ns", (1<<63 - 1) * Nanosecond},
+	{"-9223372036854775808ns", -1 << 63 * Nanosecond},
+	{"-9223372036854775.808us", -1 << 63 * Nanosecond},
+	{"-9223372036s854ms775us808ns", -1 << 63 * Nanosecond},
+	// largest negative value
+	{"-9223372036854775808ns", -1 << 63 * Nanosecond},
+	// largest negative round trip value, see https://golang.org/issue/48629
+	{"-2562047h47m16.854775808s", -1 << 63 * Nanosecond},
+	// huge string; issue 15011.
+	{"0.100000000000000000000h", 6 * Minute},
+	// This value tests the first overflow check in leadingFraction.
+	{"0.830103483285477580700h", 49*Minute + 48*Second + 372539827*Nanosecond},
+}
+
+func TestParseDuration(t *testing.T) {
+	for _, tc := range parseDurationTests {
+		d, err := ParseDuration(tc.in)
+		if err != nil || d != tc.want {
+			t.Errorf("ParseDuration(%q) = %v, %v, want %v, nil", tc.in, d, err, tc.want)
+		}
+	}
+}
+
+var parseDurationErrorTests = []struct {
+	in     string
+	expect string
+}{
+	// invalid
+	{"", `""`},
+	{"3", `"3"`},
+	{"-", `"-"`},
+	{"s", `"s"`},
+	{".", `"."`},
+	{"-.", `"-."`},
+	{".s", `".s"`},
+	{"+.s", `"+.s"`},
+	{"1d", `"1d"`},
+	{"\x85\x85", `"\x85\x85"`},
+	{"\xffff", `"\xffff"`},
+	{"hello \xffff world", `"hello \xffff world"`},
+	{"\uFFFD", `"\xef\xbf\xbd"`},                                             // utf8.RuneError
+	{"\uFFFD hello \uFFFD world", `"\xef\xbf\xbd hello \xef\xbf\xbd world"`}, // utf8.RuneError
+	// overflow
+	{"9223372036854775810ns", `"9223372036854775810ns"`},
+	{"9223372036854775808ns", `"9223372036854775808ns"`},
+	{"-9223372036854775809ns", `"-9223372036854775809ns"`},
+	{"9223372036854776us", `"9223372036854776us"`},
+	{"3000000h", `"3000000h"`},
+	{"9223372036854775.808us", `"9223372036854775.808us"`},
+	{"9223372036854ms775us808ns", `"9223372036854ms775us808ns"`},
+}
+
+func TestParseDurationErrors(t *testing.T) {
+	for _, tc := range parseDurationErrorTests {
+		_, err := ParseDuration(tc.in)
+		if err == nil {
+			t.Errorf("ParseDuration(%q) = _, nil, want _, non-nil", tc.in)
+		} else if !strings.Contains(err.Error(), tc.expect) {
+			t.Errorf("ParseDuration(%q) = _, %q, error does not contain %q", tc.in, err, tc.expect)
+		}
+	}
+}
+
+func TestParseDurationRoundTrip(t *testing.T) {
+	// https://golang.org/issue/48629
+	max0 := Duration(math.MaxInt64)
+	max1, err := ParseDuration(max0.String())
+	if err != nil || max0 != max1 {
+		t.Errorf("round-trip failed: %d => %q => %d, %v", max0, max0.String(), max1, err)
+	}
+
+	min0 := Duration(math.MinInt64)
+	min1, err := ParseDuration(min0.String())
+	if err != nil || min0 != min1 {
+		t.Errorf("round-trip failed: %d => %q => %d, %v", min0, min0.String(), min1, err)
+	}
+
+	for i := 0; i < 100; i++ {
+		// Resolutions finer than milliseconds will result in
+		// imprecise round-trips.
+		d0 := Duration(rand.Int31()) * Millisecond
+		s := d0.String()
+		d1, err := ParseDuration(s)
+		if err != nil || d0 != d1 {
+			t.Errorf("round-trip failed: %d => %q => %d, %v", d0, s, d1, err)
+		}
+	}
+}
+
+// golang.org/issue/4622
+func TestLocationRace(t *testing.T) {
+	ResetLocalOnceForTest() // reset the Once to trigger the race
+
+	c := make(chan string, 1)
+	go func() {
+		c <- Now().String()
+	}()
+	_ = Now().String()
+	<-c
+	Sleep(100 * Millisecond)
+
+	// Back to Los Angeles for subsequent tests:
+	ForceUSPacificForTesting()
+}
+
+var (
+	t Time
+	u int64
+)
+
+var mallocTest = []struct {
+	count int
+	desc  string
+	fn    func()
+}{
+	{0, `time.Now()`, func() { t = Now() }},
+	{0, `time.Now().UnixNano()`, func() { u = Now().UnixNano() }},
+	{0, `time.Now().UnixMilli()`, func() { u = Now().UnixMilli() }},
+	{0, `time.Now().UnixMicro()`, func() { u = Now().UnixMicro() }},
+}
+
+func TestCountMallocs(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping malloc count in short mode")
+	}
+	if runtime.GOMAXPROCS(0) > 1 {
+		t.Skip("skipping; GOMAXPROCS>1")
+	}
+	for _, mt := range mallocTest {
+		allocs := int(testing.AllocsPerRun(100, mt.fn))
+		if allocs > mt.count {
+			t.Errorf("%s: %d allocs, want %d", mt.desc, allocs, mt.count)
+		}
+	}
+}
+
+func TestLoadFixed(t *testing.T) {
+	// Issue 4064: handle locations without any zone transitions.
+	loc, err := LoadLocation("Etc/GMT+1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// The tzdata name Etc/GMT+1 uses "east is negative",
+	// but Go and most other systems use "east is positive".
+	// So GMT+1 corresponds to -3600 in the Go zone, not +3600.
+	name, offset := Now().In(loc).Zone()
+	// The zone abbreviation is "-01" since tzdata-2016g, and "GMT+1"
+	// on earlier versions; we accept both. (Issue #17276).
+	if !(name == "GMT+1" || name == "-01") || offset != -1*60*60 {
+		t.Errorf("Now().In(loc).Zone() = %q, %d, want %q or %q, %d",
+			name, offset, "GMT+1", "-01", -1*60*60)
+	}
+}
+
+const (
+	minDuration Duration = -1 << 63
+	maxDuration Duration = 1<<63 - 1
+)
+
+var subTests = []struct {
+	t Time
+	u Time
+	d Duration
+}{
+	{Time{}, Time{}, Duration(0)},
+	{Date(2009, 11, 23, 0, 0, 0, 1, UTC), Date(2009, 11, 23, 0, 0, 0, 0, UTC), Duration(1)},
+	{Date(2009, 11, 23, 0, 0, 0, 0, UTC), Date(2009, 11, 24, 0, 0, 0, 0, UTC), -24 * Hour},
+	{Date(2009, 11, 24, 0, 0, 0, 0, UTC), Date(2009, 11, 23, 0, 0, 0, 0, UTC), 24 * Hour},
+	{Date(-2009, 11, 24, 0, 0, 0, 0, UTC), Date(-2009, 11, 23, 0, 0, 0, 0, UTC), 24 * Hour},
+	{Time{}, Date(2109, 11, 23, 0, 0, 0, 0, UTC), Duration(minDuration)},
+	{Date(2109, 11, 23, 0, 0, 0, 0, UTC), Time{}, Duration(maxDuration)},
+	{Time{}, Date(-2109, 11, 23, 0, 0, 0, 0, UTC), Duration(maxDuration)},
+	{Date(-2109, 11, 23, 0, 0, 0, 0, UTC), Time{}, Duration(minDuration)},
+	{Date(2290, 1, 1, 0, 0, 0, 0, UTC), Date(2000, 1, 1, 0, 0, 0, 0, UTC), 290*365*24*Hour + 71*24*Hour},
+	{Date(2300, 1, 1, 0, 0, 0, 0, UTC), Date(2000, 1, 1, 0, 0, 0, 0, UTC), Duration(maxDuration)},
+	{Date(2000, 1, 1, 0, 0, 0, 0, UTC), Date(2290, 1, 1, 0, 0, 0, 0, UTC), -290*365*24*Hour - 71*24*Hour},
+	{Date(2000, 1, 1, 0, 0, 0, 0, UTC), Date(2300, 1, 1, 0, 0, 0, 0, UTC), Duration(minDuration)},
+	{Date(2311, 11, 26, 02, 16, 47, 63535996, UTC), Date(2019, 8, 16, 2, 29, 30, 268436582, UTC), 9223372036795099414},
+	{MinMonoTime, MaxMonoTime, minDuration},
+	{MaxMonoTime, MinMonoTime, maxDuration},
+}
+
+func TestSub(t *testing.T) {
+	for i, st := range subTests {
+		got := st.t.Sub(st.u)
+		if got != st.d {
+			t.Errorf("#%d: Sub(%v, %v): got %v; want %v", i, st.t, st.u, got, st.d)
+		}
+	}
+}
+
+var nsDurationTests = []struct {
+	d    Duration
+	want int64
+}{
+	{Duration(-1000), -1000},
+	{Duration(-1), -1},
+	{Duration(1), 1},
+	{Duration(1000), 1000},
+}
+
+func TestDurationNanoseconds(t *testing.T) {
+	for _, tt := range nsDurationTests {
+		if got := tt.d.Nanoseconds(); got != tt.want {
+			t.Errorf("Duration(%s).Nanoseconds() = %d; want: %d", tt.d, got, tt.want)
+		}
+	}
+}
+
+var usDurationTests = []struct {
+	d    Duration
+	want int64
+}{
+	{Duration(-1000), -1},
+	{Duration(1000), 1},
+}
+
+func TestDurationMicroseconds(t *testing.T) {
+	for _, tt := range usDurationTests {
+		if got := tt.d.Microseconds(); got != tt.want {
+			t.Errorf("Duration(%s).Microseconds() = %d; want: %d", tt.d, got, tt.want)
+		}
+	}
+}
+
+var msDurationTests = []struct {
+	d    Duration
+	want int64
+}{
+	{Duration(-1000000), -1},
+	{Duration(1000000), 1},
+}
+
+func TestDurationMilliseconds(t *testing.T) {
+	for _, tt := range msDurationTests {
+		if got := tt.d.Milliseconds(); got != tt.want {
+			t.Errorf("Duration(%s).Milliseconds() = %d; want: %d", tt.d, got, tt.want)
+		}
+	}
+}
+
+var secDurationTests = []struct {
+	d    Duration
+	want float64
+}{
+	{Duration(300000000), 0.3},
+}
+
+func TestDurationSeconds(t *testing.T) {
+	for _, tt := range secDurationTests {
+		if got := tt.d.Seconds(); got != tt.want {
+			t.Errorf("Duration(%s).Seconds() = %g; want: %g", tt.d, got, tt.want)
+		}
+	}
+}
+
+var minDurationTests = []struct {
+	d    Duration
+	want float64
+}{
+	{Duration(-60000000000), -1},
+	{Duration(-1), -1 / 60e9},
+	{Duration(1), 1 / 60e9},
+	{Duration(60000000000), 1},
+	{Duration(3000), 5e-8},
+}
+
+func TestDurationMinutes(t *testing.T) {
+	for _, tt := range minDurationTests {
+		if got := tt.d.Minutes(); got != tt.want {
+			t.Errorf("Duration(%s).Minutes() = %g; want: %g", tt.d, got, tt.want)
+		}
+	}
+}
+
+var hourDurationTests = []struct {
+	d    Duration
+	want float64
+}{
+	{Duration(-3600000000000), -1},
+	{Duration(-1), -1 / 3600e9},
+	{Duration(1), 1 / 3600e9},
+	{Duration(3600000000000), 1},
+	{Duration(36), 1e-11},
+}
+
+func TestDurationHours(t *testing.T) {
+	for _, tt := range hourDurationTests {
+		if got := tt.d.Hours(); got != tt.want {
+			t.Errorf("Duration(%s).Hours() = %g; want: %g", tt.d, got, tt.want)
+		}
+	}
+}
+
+var durationTruncateTests = []struct {
+	d    Duration
+	m    Duration
+	want Duration
+}{
+	{0, Second, 0},
+	{Minute, -7 * Second, Minute},
+	{Minute, 0, Minute},
+	{Minute, 1, Minute},
+	{Minute + 10*Second, 10 * Second, Minute + 10*Second},
+	{2*Minute + 10*Second, Minute, 2 * Minute},
+	{10*Minute + 10*Second, 3 * Minute, 9 * Minute},
+	{Minute + 10*Second, Minute + 10*Second + 1, 0},
+	{Minute + 10*Second, Hour, 0},
+	{-Minute, Second, -Minute},
+	{-10 * Minute, 3 * Minute, -9 * Minute},
+	{-10 * Minute, Hour, 0},
+}
+
+func TestDurationTruncate(t *testing.T) {
+	for _, tt := range durationTruncateTests {
+		if got := tt.d.Truncate(tt.m); got != tt.want {
+			t.Errorf("Duration(%s).Truncate(%s) = %s; want: %s", tt.d, tt.m, got, tt.want)
+		}
+	}
+}
+
+var durationRoundTests = []struct {
+	d    Duration
+	m    Duration
+	want Duration
+}{
+	{0, Second, 0},
+	{Minute, -11 * Second, Minute},
+	{Minute, 0, Minute},
+	{Minute, 1, Minute},
+	{2 * Minute, Minute, 2 * Minute},
+	{2*Minute + 10*Second, Minute, 2 * Minute},
+	{2*Minute + 30*Second, Minute, 3 * Minute},
+	{2*Minute + 50*Second, Minute, 3 * Minute},
+	{-Minute, 1, -Minute},
+	{-2 * Minute, Minute, -2 * Minute},
+	{-2*Minute - 10*Second, Minute, -2 * Minute},
+	{-2*Minute - 30*Second, Minute, -3 * Minute},
+	{-2*Minute - 50*Second, Minute, -3 * Minute},
+	{8e18, 3e18, 9e18},
+	{9e18, 5e18, 1<<63 - 1},
+	{-8e18, 3e18, -9e18},
+	{-9e18, 5e18, -1 << 63},
+	{3<<61 - 1, 3 << 61, 3 << 61},
+}
+
+func TestDurationRound(t *testing.T) {
+	for _, tt := range durationRoundTests {
+		if got := tt.d.Round(tt.m); got != tt.want {
+			t.Errorf("Duration(%s).Round(%s) = %s; want: %s", tt.d, tt.m, got, tt.want)
+		}
+	}
+}
+
+var durationAbsTests = []struct {
+	d    Duration
+	want Duration
+}{
+	{0, 0},
+	{1, 1},
+	{-1, 1},
+	{1 * Minute, 1 * Minute},
+	{-1 * Minute, 1 * Minute},
+	{minDuration, maxDuration},
+	{minDuration + 1, maxDuration},
+	{minDuration + 2, maxDuration - 1},
+	{maxDuration, maxDuration},
+	{maxDuration - 1, maxDuration - 1},
+}
+
+func TestDurationAbs(t *testing.T) {
+	for _, tt := range durationAbsTests {
+		if got := tt.d.Abs(); got != tt.want {
+			t.Errorf("Duration(%s).Abs() = %s; want: %s", tt.d, got, tt.want)
+		}
+	}
+}
+
+var defaultLocTests = []struct {
+	name string
+	f    func(t1, t2 Time) bool
+}{
+	{"After", func(t1, t2 Time) bool { return t1.After(t2) == t2.After(t1) }},
+	{"Before", func(t1, t2 Time) bool { return t1.Before(t2) == t2.Before(t1) }},
+	{"Equal", func(t1, t2 Time) bool { return t1.Equal(t2) == t2.Equal(t1) }},
+	{"Compare", func(t1, t2 Time) bool { return t1.Compare(t2) == t2.Compare(t1) }},
+
+	{"IsZero", func(t1, t2 Time) bool { return t1.IsZero() == t2.IsZero() }},
+	{"Date", func(t1, t2 Time) bool {
+		a1, b1, c1 := t1.Date()
+		a2, b2, c2 := t2.Date()
+		return a1 == a2 && b1 == b2 && c1 == c2
+	}},
+	{"Year", func(t1, t2 Time) bool { return t1.Year() == t2.Year() }},
+	{"Month", func(t1, t2 Time) bool { return t1.Month() == t2.Month() }},
+	{"Day", func(t1, t2 Time) bool { return t1.Day() == t2.Day() }},
+	{"Weekday", func(t1, t2 Time) bool { return t1.Weekday() == t2.Weekday() }},
+	{"ISOWeek", func(t1, t2 Time) bool {
+		a1, b1 := t1.ISOWeek()
+		a2, b2 := t2.ISOWeek()
+		return a1 == a2 && b1 == b2
+	}},
+	{"Clock", func(t1, t2 Time) bool {
+		a1, b1, c1 := t1.Clock()
+		a2, b2, c2 := t2.Clock()
+		return a1 == a2 && b1 == b2 && c1 == c2
+	}},
+	{"Hour", func(t1, t2 Time) bool { return t1.Hour() == t2.Hour() }},
+	{"Minute", func(t1, t2 Time) bool { return t1.Minute() == t2.Minute() }},
+	{"Second", func(t1, t2 Time) bool { return t1.Second() == t2.Second() }},
+	{"Nanosecond", func(t1, t2 Time) bool { return t1.Hour() == t2.Hour() }},
+	{"YearDay", func(t1, t2 Time) bool { return t1.YearDay() == t2.YearDay() }},
+
+	// Using Equal since Add don't modify loc using "==" will cause a fail
+	{"Add", func(t1, t2 Time) bool { return t1.Add(Hour).Equal(t2.Add(Hour)) }},
+	{"Sub", func(t1, t2 Time) bool { return t1.Sub(t2) == t2.Sub(t1) }},
+
+	//Original caus for this test case bug 15852
+	{"AddDate", func(t1, t2 Time) bool { return t1.AddDate(1991, 9, 3) == t2.AddDate(1991, 9, 3) }},
+
+	{"UTC", func(t1, t2 Time) bool { return t1.UTC() == t2.UTC() }},
+	{"Local", func(t1, t2 Time) bool { return t1.Local() == t2.Local() }},
+	{"In", func(t1, t2 Time) bool { return t1.In(UTC) == t2.In(UTC) }},
+
+	{"Local", func(t1, t2 Time) bool { return t1.Local() == t2.Local() }},
+	{"Zone", func(t1, t2 Time) bool {
+		a1, b1 := t1.Zone()
+		a2, b2 := t2.Zone()
+		return a1 == a2 && b1 == b2
+	}},
+
+	{"Unix", func(t1, t2 Time) bool { return t1.Unix() == t2.Unix() }},
+	{"UnixNano", func(t1, t2 Time) bool { return t1.UnixNano() == t2.UnixNano() }},
+	{"UnixMilli", func(t1, t2 Time) bool { return t1.UnixMilli() == t2.UnixMilli() }},
+	{"UnixMicro", func(t1, t2 Time) bool { return t1.UnixMicro() == t2.UnixMicro() }},
+
+	{"MarshalBinary", func(t1, t2 Time) bool {
+		a1, b1 := t1.MarshalBinary()
+		a2, b2 := t2.MarshalBinary()
+		return bytes.Equal(a1, a2) && b1 == b2
+	}},
+	{"GobEncode", func(t1, t2 Time) bool {
+		a1, b1 := t1.GobEncode()
+		a2, b2 := t2.GobEncode()
+		return bytes.Equal(a1, a2) && b1 == b2
+	}},
+	{"MarshalJSON", func(t1, t2 Time) bool {
+		a1, b1 := t1.MarshalJSON()
+		a2, b2 := t2.MarshalJSON()
+		return bytes.Equal(a1, a2) && b1 == b2
+	}},
+	{"MarshalText", func(t1, t2 Time) bool {
+		a1, b1 := t1.MarshalText()
+		a2, b2 := t2.MarshalText()
+		return bytes.Equal(a1, a2) && b1 == b2
+	}},
+
+	{"Truncate", func(t1, t2 Time) bool { return t1.Truncate(Hour).Equal(t2.Truncate(Hour)) }},
+	{"Round", func(t1, t2 Time) bool { return t1.Round(Hour).Equal(t2.Round(Hour)) }},
+
+	{"== Time{}", func(t1, t2 Time) bool { return (t1 == Time{}) == (t2 == Time{}) }},
+}
+
+func TestDefaultLoc(t *testing.T) {
+	// Verify that all of Time's methods behave identically if loc is set to
+	// nil or UTC.
+	for _, tt := range defaultLocTests {
+		t1 := Time{}
+		t2 := Time{}.UTC()
+		if !tt.f(t1, t2) {
+			t.Errorf("Time{} and Time{}.UTC() behave differently for %s", tt.name)
+		}
+	}
+}
+
+func BenchmarkNow(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		t = Now()
+	}
+}
+
+func BenchmarkNowUnixNano(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		u = Now().UnixNano()
+	}
+}
+
+func BenchmarkNowUnixMilli(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		u = Now().UnixMilli()
+	}
+}
+
+func BenchmarkNowUnixMicro(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		u = Now().UnixMicro()
+	}
+}
+
+func BenchmarkFormat(b *testing.B) {
+	t := Unix(1265346057, 0)
+	for i := 0; i < b.N; i++ {
+		t.Format("Mon Jan  2 15:04:05 2006")
+	}
+}
+
+func BenchmarkFormatRFC3339(b *testing.B) {
+	t := Unix(1265346057, 0)
+	for i := 0; i < b.N; i++ {
+		t.Format("2006-01-02T15:04:05Z07:00")
+	}
+}
+
+func BenchmarkFormatRFC3339Nano(b *testing.B) {
+	t := Unix(1265346057, 0)
+	for i := 0; i < b.N; i++ {
+		t.Format("2006-01-02T15:04:05.999999999Z07:00")
+	}
+}
+
+func BenchmarkFormatNow(b *testing.B) {
+	// Like BenchmarkFormat, but easier, because the time zone
+	// lookup cache is optimized for the present.
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		t.Format("Mon Jan  2 15:04:05 2006")
+	}
+}
+
+func BenchmarkMarshalJSON(b *testing.B) {
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		t.MarshalJSON()
+	}
+}
+
+func BenchmarkMarshalText(b *testing.B) {
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		t.MarshalText()
+	}
+}
+
+func BenchmarkParse(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Parse(ANSIC, "Mon Jan  2 15:04:05 2006")
+	}
+}
+
+const testdataRFC3339UTC = "2020-08-22T11:27:43.123456789Z"
+
+func BenchmarkParseRFC3339UTC(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Parse(RFC3339, testdataRFC3339UTC)
+	}
+}
+
+var testdataRFC3339UTCBytes = []byte(testdataRFC3339UTC)
+
+func BenchmarkParseRFC3339UTCBytes(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Parse(RFC3339, string(testdataRFC3339UTCBytes))
+	}
+}
+
+const testdataRFC3339TZ = "2020-08-22T11:27:43.123456789-02:00"
+
+func BenchmarkParseRFC3339TZ(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Parse(RFC3339, testdataRFC3339TZ)
+	}
+}
+
+var testdataRFC3339TZBytes = []byte(testdataRFC3339TZ)
+
+func BenchmarkParseRFC3339TZBytes(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Parse(RFC3339, string(testdataRFC3339TZBytes))
+	}
+}
+
+func BenchmarkParseDuration(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseDuration("9007199254.740993ms")
+		ParseDuration("9007199254740993ns")
+	}
+}
+
+func BenchmarkHour(b *testing.B) {
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		_ = t.Hour()
+	}
+}
+
+func BenchmarkSecond(b *testing.B) {
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		_ = t.Second()
+	}
+}
+
+func BenchmarkYear(b *testing.B) {
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		_ = t.Year()
+	}
+}
+
+func BenchmarkDay(b *testing.B) {
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		_ = t.Day()
+	}
+}
+
+func BenchmarkISOWeek(b *testing.B) {
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		_, _ = t.ISOWeek()
+	}
+}
+
+func BenchmarkGoString(b *testing.B) {
+	t := Now()
+	for i := 0; i < b.N; i++ {
+		_ = t.GoString()
+	}
+}
+
+func BenchmarkUnmarshalText(b *testing.B) {
+	var t Time
+	in := []byte("2020-08-22T11:27:43.123456789-02:00")
+	for i := 0; i < b.N; i++ {
+		t.UnmarshalText(in)
+	}
+}
+
+func TestMarshalBinaryZeroTime(t *testing.T) {
+	t0 := Time{}
+	enc, err := t0.MarshalBinary()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t1 := Now() // not zero
+	if err := t1.UnmarshalBinary(enc); err != nil {
+		t.Fatal(err)
+	}
+	if t1 != t0 {
+		t.Errorf("t0=%#v\nt1=%#v\nwant identical structures", t0, t1)
+	}
+}
+
+func TestMarshalBinaryVersion2(t *testing.T) {
+	t0, err := Parse(RFC3339, "1880-01-01T00:00:00Z")
+	if err != nil {
+		t.Errorf("Failed to parse time, error = %v", err)
+	}
+	loc, err := LoadLocation("US/Eastern")
+	if err != nil {
+		t.Errorf("Failed to load location, error = %v", err)
+	}
+	t1 := t0.In(loc)
+	b, err := t1.MarshalBinary()
+	if err != nil {
+		t.Errorf("Failed to Marshal, error = %v", err)
+	}
+
+	t2 := Time{}
+	err = t2.UnmarshalBinary(b)
+	if err != nil {
+		t.Errorf("Failed to Unmarshal, error = %v", err)
+	}
+
+	if !(t0.Equal(t1) && t1.Equal(t2)) {
+		if !t0.Equal(t1) {
+			t.Errorf("The result t1: %+v after Marshal is not matched original t0: %+v", t1, t0)
+		}
+		if !t1.Equal(t2) {
+			t.Errorf("The result t2: %+v after Unmarshal is not matched original t1: %+v", t2, t1)
+		}
+	}
+}
+
+func TestUnmarshalTextAllocations(t *testing.T) {
+	in := []byte(testdataRFC3339UTC) // short enough to be stack allocated
+	if allocs := testing.AllocsPerRun(100, func() {
+		var t Time
+		t.UnmarshalText(in)
+	}); allocs != 0 {
+		t.Errorf("got %v allocs, want 0 allocs", allocs)
+	}
+}
+
+// Issue 17720: Zero value of time.Month fails to print
+func TestZeroMonthString(t *testing.T) {
+	if got, want := Month(0).String(), "%!Month(0)"; got != want {
+		t.Errorf("zero month = %q; want %q", got, want)
+	}
+}
+
+// Issue 24692: Out of range weekday panics
+func TestWeekdayString(t *testing.T) {
+	if got, want := Weekday(Tuesday).String(), "Tuesday"; got != want {
+		t.Errorf("Tuesday weekday = %q; want %q", got, want)
+	}
+	if got, want := Weekday(14).String(), "%!Weekday(14)"; got != want {
+		t.Errorf("14th weekday = %q; want %q", got, want)
+	}
+}
+
+func TestReadFileLimit(t *testing.T) {
+	const zero = "/dev/zero"
+	if _, err := os.Stat(zero); err != nil {
+		t.Skip("skipping test without a /dev/zero")
+	}
+	_, err := ReadFile(zero)
+	if err == nil || !strings.Contains(err.Error(), "is too large") {
+		t.Errorf("readFile(%q) error = %v; want error containing 'is too large'", zero, err)
+	}
+}
+
+// Issue 25686: hard crash on concurrent timer access.
+// Issue 37400: panic with "racy use of timers"
+// This test deliberately invokes a race condition.
+// We are testing that we don't crash with "fatal error: panic holding locks",
+// and that we also don't panic.
+func TestConcurrentTimerReset(t *testing.T) {
+	const goroutines = 8
+	const tries = 1000
+	var wg sync.WaitGroup
+	wg.Add(goroutines)
+	timer := NewTimer(Hour)
+	for i := 0; i < goroutines; i++ {
+		go func(i int) {
+			defer wg.Done()
+			for j := 0; j < tries; j++ {
+				timer.Reset(Hour + Duration(i*j))
+			}
+		}(i)
+	}
+	wg.Wait()
+}
+
+// Issue 37400: panic with "racy use of timers".
+func TestConcurrentTimerResetStop(t *testing.T) {
+	const goroutines = 8
+	const tries = 1000
+	var wg sync.WaitGroup
+	wg.Add(goroutines * 2)
+	timer := NewTimer(Hour)
+	for i := 0; i < goroutines; i++ {
+		go func(i int) {
+			defer wg.Done()
+			for j := 0; j < tries; j++ {
+				timer.Reset(Hour + Duration(i*j))
+			}
+		}(i)
+		go func(i int) {
+			defer wg.Done()
+			timer.Stop()
+		}(i)
+	}
+	wg.Wait()
+}
+
+func TestTimeIsDST(t *testing.T) {
+	undo := DisablePlatformSources()
+	defer undo()
+
+	tzWithDST, err := LoadLocation("Australia/Sydney")
+	if err != nil {
+		t.Fatalf("could not load tz 'Australia/Sydney': %v", err)
+	}
+	tzWithoutDST, err := LoadLocation("Australia/Brisbane")
+	if err != nil {
+		t.Fatalf("could not load tz 'Australia/Brisbane': %v", err)
+	}
+	tzFixed := FixedZone("FIXED_TIME", 12345)
+
+	tests := [...]struct {
+		time Time
+		want bool
+	}{
+		0: {Date(2009, 1, 1, 12, 0, 0, 0, UTC), false},
+		1: {Date(2009, 6, 1, 12, 0, 0, 0, UTC), false},
+		2: {Date(2009, 1, 1, 12, 0, 0, 0, tzWithDST), true},
+		3: {Date(2009, 6, 1, 12, 0, 0, 0, tzWithDST), false},
+		4: {Date(2009, 1, 1, 12, 0, 0, 0, tzWithoutDST), false},
+		5: {Date(2009, 6, 1, 12, 0, 0, 0, tzWithoutDST), false},
+		6: {Date(2009, 1, 1, 12, 0, 0, 0, tzFixed), false},
+		7: {Date(2009, 6, 1, 12, 0, 0, 0, tzFixed), false},
+	}
+
+	for i, tt := range tests {
+		got := tt.time.IsDST()
+		if got != tt.want {
+			t.Errorf("#%d:: (%#v).IsDST()=%t, want %t", i, tt.time.Format(RFC3339), got, tt.want)
+		}
+	}
+}
+
+func TestTimeAddSecOverflow(t *testing.T) {
+	// Test it with positive delta.
+	var maxInt64 int64 = 1<<63 - 1
+	timeExt := maxInt64 - UnixToInternal - 50
+	notMonoTime := Unix(timeExt, 0)
+	for i := int64(0); i < 100; i++ {
+		sec := notMonoTime.Unix()
+		notMonoTime = notMonoTime.Add(Duration(i * 1e9))
+		if newSec := notMonoTime.Unix(); newSec != sec+i && newSec+UnixToInternal != maxInt64 {
+			t.Fatalf("time ext: %d overflows with positive delta, overflow threshold: %d", newSec, maxInt64)
+		}
+	}
+
+	// Test it with negative delta.
+	maxInt64 = -maxInt64
+	notMonoTime = NotMonoNegativeTime
+	for i := int64(0); i > -100; i-- {
+		sec := notMonoTime.Unix()
+		notMonoTime = notMonoTime.Add(Duration(i * 1e9))
+		if newSec := notMonoTime.Unix(); newSec != sec+i && newSec+UnixToInternal != maxInt64 {
+			t.Fatalf("time ext: %d overflows with positive delta, overflow threshold: %d", newSec, maxInt64)
+		}
+	}
+}
+
+// Issue 49284: time: ParseInLocation incorrectly because of Daylight Saving Time
+func TestTimeWithZoneTransition(t *testing.T) {
+	undo := DisablePlatformSources()
+	defer undo()
+
+	loc, err := LoadLocation("Asia/Shanghai")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tests := [...]struct {
+		give Time
+		want Time
+	}{
+		// 14 Apr 1991 - Daylight Saving Time Started
+		// When time of "Asia/Shanghai" was about to reach
+		// Sunday, 14 April 1991, 02:00:00 clocks were turned forward 1 hour to
+		// Sunday, 14 April 1991, 03:00:00 local daylight time instead.
+		// The UTC time was 13 April 1991, 18:00:00
+		0: {Date(1991, April, 13, 17, 50, 0, 0, loc), Date(1991, April, 13, 9, 50, 0, 0, UTC)},
+		1: {Date(1991, April, 13, 18, 0, 0, 0, loc), Date(1991, April, 13, 10, 0, 0, 0, UTC)},
+		2: {Date(1991, April, 14, 1, 50, 0, 0, loc), Date(1991, April, 13, 17, 50, 0, 0, UTC)},
+		3: {Date(1991, April, 14, 3, 0, 0, 0, loc), Date(1991, April, 13, 18, 0, 0, 0, UTC)},
+
+		// 15 Sep 1991 - Daylight Saving Time Ended
+		// When local daylight time of "Asia/Shanghai" was about to reach
+		// Sunday, 15 September 1991, 02:00:00 clocks were turned backward 1 hour to
+		// Sunday, 15 September 1991, 01:00:00 local standard time instead.
+		// The UTC time was 14 September 1991, 17:00:00
+		4: {Date(1991, September, 14, 16, 50, 0, 0, loc), Date(1991, September, 14, 7, 50, 0, 0, UTC)},
+		5: {Date(1991, September, 14, 17, 0, 0, 0, loc), Date(1991, September, 14, 8, 0, 0, 0, UTC)},
+		6: {Date(1991, September, 15, 0, 50, 0, 0, loc), Date(1991, September, 14, 15, 50, 0, 0, UTC)},
+		7: {Date(1991, September, 15, 2, 00, 0, 0, loc), Date(1991, September, 14, 18, 00, 0, 0, UTC)},
+	}
+
+	for i, tt := range tests {
+		if !tt.give.Equal(tt.want) {
+			t.Errorf("#%d:: %#v is not equal to %#v", i, tt.give.Format(RFC3339), tt.want.Format(RFC3339))
+		}
+	}
+}
+
+func TestZoneBounds(t *testing.T) {
+	undo := DisablePlatformSources()
+	defer undo()
+	loc, err := LoadLocation("Asia/Shanghai")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// The ZoneBounds of a UTC location would just return two zero Time.
+	for _, test := range utctests {
+		sec := test.seconds
+		golden := &test.golden
+		tm := Unix(sec, 0).UTC()
+		start, end := tm.ZoneBounds()
+		if !(start.IsZero() && end.IsZero()) {
+			t.Errorf("ZoneBounds of %+v expects two zero Time, got:\n  start=%v\n  end=%v", *golden, start, end)
+		}
+	}
+
+	// If the zone begins at the beginning of time, start will be returned as a zero Time.
+	// Use math.MinInt32 to avoid overflow of int arguments on 32-bit systems.
+	beginTime := Date(math.MinInt32, January, 1, 0, 0, 0, 0, loc)
+	start, end := beginTime.ZoneBounds()
+	if !start.IsZero() || end.IsZero() {
+		t.Errorf("ZoneBounds of %v expects start is zero Time, got:\n  start=%v\n  end=%v", beginTime, start, end)
+	}
+
+	// If the zone goes on forever, end will be returned as a zero Time.
+	// Use math.MaxInt32 to avoid overflow of int arguments on 32-bit systems.
+	foreverTime := Date(math.MaxInt32, January, 1, 0, 0, 0, 0, loc)
+	start, end = foreverTime.ZoneBounds()
+	if start.IsZero() || !end.IsZero() {
+		t.Errorf("ZoneBounds of %v expects end is zero Time, got:\n  start=%v\n  end=%v", foreverTime, start, end)
+	}
+
+	// Check some real-world cases to make sure we're getting the right bounds.
+	boundOne := Date(1990, September, 16, 1, 0, 0, 0, loc)
+	boundTwo := Date(1991, April, 14, 3, 0, 0, 0, loc)
+	boundThree := Date(1991, September, 15, 1, 0, 0, 0, loc)
+	makeLocalTime := func(sec int64) Time { return Unix(sec, 0) }
+	realTests := [...]struct {
+		giveTime  Time
+		wantStart Time
+		wantEnd   Time
+	}{
+		// The ZoneBounds of "Asia/Shanghai" Daylight Saving Time
+		0: {Date(1991, April, 13, 17, 50, 0, 0, loc), boundOne, boundTwo},
+		1: {Date(1991, April, 13, 18, 0, 0, 0, loc), boundOne, boundTwo},
+		2: {Date(1991, April, 14, 1, 50, 0, 0, loc), boundOne, boundTwo},
+		3: {boundTwo, boundTwo, boundThree},
+		4: {Date(1991, September, 14, 16, 50, 0, 0, loc), boundTwo, boundThree},
+		5: {Date(1991, September, 14, 17, 0, 0, 0, loc), boundTwo, boundThree},
+		6: {Date(1991, September, 15, 0, 50, 0, 0, loc), boundTwo, boundThree},
+
+		// The ZoneBounds of a "Asia/Shanghai" after the last transition (Standard Time)
+		7:  {boundThree, boundThree, Time{}},
+		8:  {Date(1991, December, 15, 1, 50, 0, 0, loc), boundThree, Time{}},
+		9:  {Date(1992, April, 13, 17, 50, 0, 0, loc), boundThree, Time{}},
+		10: {Date(1992, April, 13, 18, 0, 0, 0, loc), boundThree, Time{}},
+		11: {Date(1992, April, 14, 1, 50, 0, 0, loc), boundThree, Time{}},
+		12: {Date(1992, September, 14, 16, 50, 0, 0, loc), boundThree, Time{}},
+		13: {Date(1992, September, 14, 17, 0, 0, 0, loc), boundThree, Time{}},
+		14: {Date(1992, September, 15, 0, 50, 0, 0, loc), boundThree, Time{}},
+
+		// The ZoneBounds of a local time would return two local Time.
+		// Note: We preloaded "America/Los_Angeles" as time.Local for testing
+		15: {makeLocalTime(0), makeLocalTime(-5756400), makeLocalTime(9972000)},
+		16: {makeLocalTime(1221681866), makeLocalTime(1205056800), makeLocalTime(1225616400)},
+		17: {makeLocalTime(2152173599), makeLocalTime(2145916800), makeLocalTime(2152173600)},
+		18: {makeLocalTime(2152173600), makeLocalTime(2152173600), makeLocalTime(2172733200)},
+		19: {makeLocalTime(2152173601), makeLocalTime(2152173600), makeLocalTime(2172733200)},
+		20: {makeLocalTime(2159200800), makeLocalTime(2152173600), makeLocalTime(2172733200)},
+		21: {makeLocalTime(2172733199), makeLocalTime(2152173600), makeLocalTime(2172733200)},
+		22: {makeLocalTime(2172733200), makeLocalTime(2172733200), makeLocalTime(2177452800)},
+	}
+	for i, tt := range realTests {
+		start, end := tt.giveTime.ZoneBounds()
+		if !start.Equal(tt.wantStart) || !end.Equal(tt.wantEnd) {
+			t.Errorf("#%d:: ZoneBounds of %v expects right bounds:\n  got start=%v\n  want start=%v\n  got end=%v\n  want end=%v",
+				i, tt.giveTime, start, tt.wantStart, end, tt.wantEnd)
+		}
+	}
+}
diff --git a/src/time/tzdata/tzdata.go b/src/time/tzdata/tzdata.go
new file mode 100644
index 0000000..95c759b
--- /dev/null
+++ b/src/time/tzdata/tzdata.go
@@ -0,0 +1,110 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package tzdata provides an embedded copy of the timezone database.
+// If this package is imported anywhere in the program, then if
+// the time package cannot find tzdata files on the system,
+// it will use this embedded information.
+//
+// Importing this package will increase the size of a program by about
+// 450 KB.
+//
+// This package should normally be imported by a program's main package,
+// not by a library. Libraries normally shouldn't decide whether to
+// include the timezone database in a program.
+//
+// This package will be automatically imported if you build with
+// -tags timetzdata.
+package tzdata
+
+// The test for this package is time/tzdata_test.go.
+
+import (
+	"errors"
+	"syscall"
+	_ "unsafe" // for go:linkname
+)
+
+// registerLoadFromEmbeddedTZData is defined in package time.
+//
+//go:linkname registerLoadFromEmbeddedTZData time.registerLoadFromEmbeddedTZData
+func registerLoadFromEmbeddedTZData(func(string) (string, error))
+
+func init() {
+	registerLoadFromEmbeddedTZData(loadFromEmbeddedTZData)
+}
+
+// get4s returns the little-endian 32-bit value at the start of s.
+func get4s(s string) int {
+	if len(s) < 4 {
+		return 0
+	}
+	return int(s[0]) | int(s[1])<<8 | int(s[2])<<16 | int(s[3])<<24
+}
+
+// get2s returns the little-endian 16-bit value at the start of s.
+func get2s(s string) int {
+	if len(s) < 2 {
+		return 0
+	}
+	return int(s[0]) | int(s[1])<<8
+}
+
+// loadFromEmbeddedTZData returns the contents of the file with the given
+// name in an uncompressed zip file, where the contents of the file can
+// be found in embeddedTzdata.
+// This is similar to time.loadTzinfoFromZip.
+func loadFromEmbeddedTZData(name string) (string, error) {
+	const (
+		zecheader = 0x06054b50
+		zcheader  = 0x02014b50
+		ztailsize = 22
+
+		zheadersize = 30
+		zheader     = 0x04034b50
+	)
+
+	// zipdata is provided by zzipdata.go,
+	// which is generated by cmd/dist during make.bash.
+	z := zipdata
+
+	idx := len(z) - ztailsize
+	n := get2s(z[idx+10:])
+	idx = get4s(z[idx+16:])
+
+	for i := 0; i < n; i++ {
+		// See time.loadTzinfoFromZip for zip entry layout.
+		if get4s(z[idx:]) != zcheader {
+			break
+		}
+		meth := get2s(z[idx+10:])
+		size := get4s(z[idx+24:])
+		namelen := get2s(z[idx+28:])
+		xlen := get2s(z[idx+30:])
+		fclen := get2s(z[idx+32:])
+		off := get4s(z[idx+42:])
+		zname := z[idx+46 : idx+46+namelen]
+		idx += 46 + namelen + xlen + fclen
+		if zname != name {
+			continue
+		}
+		if meth != 0 {
+			return "", errors.New("unsupported compression for " + name + " in embedded tzdata")
+		}
+
+		// See time.loadTzinfoFromZip for zip per-file header layout.
+		idx = off
+		if get4s(z[idx:]) != zheader ||
+			get2s(z[idx+8:]) != meth ||
+			get2s(z[idx+26:]) != namelen ||
+			z[idx+30:idx+30+namelen] != name {
+			return "", errors.New("corrupt embedded tzdata")
+		}
+		xlen = get2s(z[idx+28:])
+		idx += 30 + namelen + xlen
+		return z[idx : idx+size], nil
+	}
+
+	return "", syscall.ENOENT
+}
diff --git a/src/time/tzdata_test.go b/src/time/tzdata_test.go
new file mode 100644
index 0000000..33c6589
--- /dev/null
+++ b/src/time/tzdata_test.go
@@ -0,0 +1,99 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"reflect"
+	"testing"
+	"time"
+	_ "time/tzdata"
+)
+
+var zones = []string{
+	"Asia/Jerusalem",
+	"America/Los_Angeles",
+}
+
+func TestEmbeddedTZData(t *testing.T) {
+	undo := time.DisablePlatformSources()
+	defer undo()
+
+	for _, zone := range zones {
+		ref, err := time.LoadLocation(zone)
+		if err != nil {
+			t.Errorf("LoadLocation(%q): %v", zone, err)
+			continue
+		}
+
+		embedded, err := time.LoadFromEmbeddedTZData(zone)
+		if err != nil {
+			t.Errorf("LoadFromEmbeddedTZData(%q): %v", zone, err)
+			continue
+		}
+		sample, err := time.LoadLocationFromTZData(zone, []byte(embedded))
+		if err != nil {
+			t.Errorf("LoadLocationFromTZData failed for %q: %v", zone, err)
+			continue
+		}
+
+		// Compare the name and zone fields of ref and sample.
+		// The tx field changes faster as tzdata is updated.
+		// The cache fields are expected to differ.
+		v1 := reflect.ValueOf(ref).Elem()
+		v2 := reflect.ValueOf(sample).Elem()
+		typ := v1.Type()
+		nf := typ.NumField()
+		found := 0
+		for i := 0; i < nf; i++ {
+			ft := typ.Field(i)
+			if ft.Name != "name" && ft.Name != "zone" {
+				continue
+			}
+			found++
+			if !equal(t, v1.Field(i), v2.Field(i)) {
+				t.Errorf("zone %s: system and embedded tzdata field %s differs", zone, ft.Name)
+			}
+		}
+		if found != 2 {
+			t.Errorf("test must be updated for change to time.Location struct")
+		}
+	}
+}
+
+// equal is a small version of reflect.DeepEqual that we use to
+// compare the values of zoneinfo unexported fields.
+func equal(t *testing.T, f1, f2 reflect.Value) bool {
+	switch f1.Type().Kind() {
+	case reflect.Slice:
+		if f1.Len() != f2.Len() {
+			return false
+		}
+		for i := 0; i < f1.Len(); i++ {
+			if !equal(t, f1.Index(i), f2.Index(i)) {
+				return false
+			}
+		}
+		return true
+	case reflect.Struct:
+		nf := f1.Type().NumField()
+		for i := 0; i < nf; i++ {
+			if !equal(t, f1.Field(i), f2.Field(i)) {
+				return false
+			}
+		}
+		return true
+	case reflect.String:
+		return f1.String() == f2.String()
+	case reflect.Bool:
+		return f1.Bool() == f2.Bool()
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return f1.Int() == f2.Int()
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return f1.Uint() == f2.Uint()
+	default:
+		t.Errorf("test internal error: unsupported kind %v", f1.Type().Kind())
+		return true
+	}
+}
diff --git a/src/time/zoneinfo.go b/src/time/zoneinfo.go
new file mode 100644
index 0000000..4edcf3d
--- /dev/null
+++ b/src/time/zoneinfo.go
@@ -0,0 +1,708 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+import (
+	"errors"
+	"sync"
+	"syscall"
+)
+
+//go:generate env ZONEINFO=$GOROOT/lib/time/zoneinfo.zip go run genzabbrs.go -output zoneinfo_abbrs_windows.go
+
+// A Location maps time instants to the zone in use at that time.
+// Typically, the Location represents the collection of time offsets
+// in use in a geographical area. For many Locations the time offset varies
+// depending on whether daylight savings time is in use at the time instant.
+type Location struct {
+	name string
+	zone []zone
+	tx   []zoneTrans
+
+	// The tzdata information can be followed by a string that describes
+	// how to handle DST transitions not recorded in zoneTrans.
+	// The format is the TZ environment variable without a colon; see
+	// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html.
+	// Example string, for America/Los_Angeles: PST8PDT,M3.2.0,M11.1.0
+	extend string
+
+	// Most lookups will be for the current time.
+	// To avoid the binary search through tx, keep a
+	// static one-element cache that gives the correct
+	// zone for the time when the Location was created.
+	// if cacheStart <= t < cacheEnd,
+	// lookup can return cacheZone.
+	// The units for cacheStart and cacheEnd are seconds
+	// since January 1, 1970 UTC, to match the argument
+	// to lookup.
+	cacheStart int64
+	cacheEnd   int64
+	cacheZone  *zone
+}
+
+// A zone represents a single time zone such as CET.
+type zone struct {
+	name   string // abbreviated name, "CET"
+	offset int    // seconds east of UTC
+	isDST  bool   // is this zone Daylight Savings Time?
+}
+
+// A zoneTrans represents a single time zone transition.
+type zoneTrans struct {
+	when         int64 // transition time, in seconds since 1970 GMT
+	index        uint8 // the index of the zone that goes into effect at that time
+	isstd, isutc bool  // ignored - no idea what these mean
+}
+
+// alpha and omega are the beginning and end of time for zone
+// transitions.
+const (
+	alpha = -1 << 63  // math.MinInt64
+	omega = 1<<63 - 1 // math.MaxInt64
+)
+
+// UTC represents Universal Coordinated Time (UTC).
+var UTC *Location = &utcLoc
+
+// utcLoc is separate so that get can refer to &utcLoc
+// and ensure that it never returns a nil *Location,
+// even if a badly behaved client has changed UTC.
+var utcLoc = Location{name: "UTC"}
+
+// Local represents the system's local time zone.
+// On Unix systems, Local consults the TZ environment
+// variable to find the time zone to use. No TZ means
+// use the system default /etc/localtime.
+// TZ="" means use UTC.
+// TZ="foo" means use file foo in the system timezone directory.
+var Local *Location = &localLoc
+
+// localLoc is separate so that initLocal can initialize
+// it even if a client has changed Local.
+var localLoc Location
+var localOnce sync.Once
+
+func (l *Location) get() *Location {
+	if l == nil {
+		return &utcLoc
+	}
+	if l == &localLoc {
+		localOnce.Do(initLocal)
+	}
+	return l
+}
+
+// String returns a descriptive name for the time zone information,
+// corresponding to the name argument to LoadLocation or FixedZone.
+func (l *Location) String() string {
+	return l.get().name
+}
+
+var unnamedFixedZones []*Location
+var unnamedFixedZonesOnce sync.Once
+
+// FixedZone returns a Location that always uses
+// the given zone name and offset (seconds east of UTC).
+func FixedZone(name string, offset int) *Location {
+	// Most calls to FixedZone have an unnamed zone with an offset by the hour.
+	// Optimize for that case by returning the same *Location for a given hour.
+	const hoursBeforeUTC = 12
+	const hoursAfterUTC = 14
+	hour := offset / 60 / 60
+	if name == "" && -hoursBeforeUTC <= hour && hour <= +hoursAfterUTC && hour*60*60 == offset {
+		unnamedFixedZonesOnce.Do(func() {
+			unnamedFixedZones = make([]*Location, hoursBeforeUTC+1+hoursAfterUTC)
+			for hr := -hoursBeforeUTC; hr <= +hoursAfterUTC; hr++ {
+				unnamedFixedZones[hr+hoursBeforeUTC] = fixedZone("", hr*60*60)
+			}
+		})
+		return unnamedFixedZones[hour+hoursBeforeUTC]
+	}
+	return fixedZone(name, offset)
+}
+
+func fixedZone(name string, offset int) *Location {
+	l := &Location{
+		name:       name,
+		zone:       []zone{{name, offset, false}},
+		tx:         []zoneTrans{{alpha, 0, false, false}},
+		cacheStart: alpha,
+		cacheEnd:   omega,
+	}
+	l.cacheZone = &l.zone[0]
+	return l
+}
+
+// lookup returns information about the time zone in use at an
+// instant in time expressed as seconds since January 1, 1970 00:00:00 UTC.
+//
+// The returned information gives the name of the zone (such as "CET"),
+// the start and end times bracketing sec when that zone is in effect,
+// the offset in seconds east of UTC (such as -5*60*60), and whether
+// the daylight savings is being observed at that time.
+func (l *Location) lookup(sec int64) (name string, offset int, start, end int64, isDST bool) {
+	l = l.get()
+
+	if len(l.zone) == 0 {
+		name = "UTC"
+		offset = 0
+		start = alpha
+		end = omega
+		isDST = false
+		return
+	}
+
+	if zone := l.cacheZone; zone != nil && l.cacheStart <= sec && sec < l.cacheEnd {
+		name = zone.name
+		offset = zone.offset
+		start = l.cacheStart
+		end = l.cacheEnd
+		isDST = zone.isDST
+		return
+	}
+
+	if len(l.tx) == 0 || sec < l.tx[0].when {
+		zone := &l.zone[l.lookupFirstZone()]
+		name = zone.name
+		offset = zone.offset
+		start = alpha
+		if len(l.tx) > 0 {
+			end = l.tx[0].when
+		} else {
+			end = omega
+		}
+		isDST = zone.isDST
+		return
+	}
+
+	// Binary search for entry with largest time <= sec.
+	// Not using sort.Search to avoid dependencies.
+	tx := l.tx
+	end = omega
+	lo := 0
+	hi := len(tx)
+	for hi-lo > 1 {
+		m := lo + (hi-lo)/2
+		lim := tx[m].when
+		if sec < lim {
+			end = lim
+			hi = m
+		} else {
+			lo = m
+		}
+	}
+	zone := &l.zone[tx[lo].index]
+	name = zone.name
+	offset = zone.offset
+	start = tx[lo].when
+	// end = maintained during the search
+	isDST = zone.isDST
+
+	// If we're at the end of the known zone transitions,
+	// try the extend string.
+	if lo == len(tx)-1 && l.extend != "" {
+		if ename, eoffset, estart, eend, eisDST, ok := tzset(l.extend, start, sec); ok {
+			return ename, eoffset, estart, eend, eisDST
+		}
+	}
+
+	return
+}
+
+// lookupFirstZone returns the index of the time zone to use for times
+// before the first transition time, or when there are no transition
+// times.
+//
+// The reference implementation in localtime.c from
+// https://www.iana.org/time-zones/repository/releases/tzcode2013g.tar.gz
+// implements the following algorithm for these cases:
+//  1. If the first zone is unused by the transitions, use it.
+//  2. Otherwise, if there are transition times, and the first
+//     transition is to a zone in daylight time, find the first
+//     non-daylight-time zone before and closest to the first transition
+//     zone.
+//  3. Otherwise, use the first zone that is not daylight time, if
+//     there is one.
+//  4. Otherwise, use the first zone.
+func (l *Location) lookupFirstZone() int {
+	// Case 1.
+	if !l.firstZoneUsed() {
+		return 0
+	}
+
+	// Case 2.
+	if len(l.tx) > 0 && l.zone[l.tx[0].index].isDST {
+		for zi := int(l.tx[0].index) - 1; zi >= 0; zi-- {
+			if !l.zone[zi].isDST {
+				return zi
+			}
+		}
+	}
+
+	// Case 3.
+	for zi := range l.zone {
+		if !l.zone[zi].isDST {
+			return zi
+		}
+	}
+
+	// Case 4.
+	return 0
+}
+
+// firstZoneUsed reports whether the first zone is used by some
+// transition.
+func (l *Location) firstZoneUsed() bool {
+	for _, tx := range l.tx {
+		if tx.index == 0 {
+			return true
+		}
+	}
+	return false
+}
+
+// tzset takes a timezone string like the one found in the TZ environment
+// variable, the time of the last time zone transition expressed as seconds
+// since January 1, 1970 00:00:00 UTC, and a time expressed the same way.
+// We call this a tzset string since in C the function tzset reads TZ.
+// The return values are as for lookup, plus ok which reports whether the
+// parse succeeded.
+func tzset(s string, lastTxSec, sec int64) (name string, offset int, start, end int64, isDST, ok bool) {
+	var (
+		stdName, dstName     string
+		stdOffset, dstOffset int
+	)
+
+	stdName, s, ok = tzsetName(s)
+	if ok {
+		stdOffset, s, ok = tzsetOffset(s)
+	}
+	if !ok {
+		return "", 0, 0, 0, false, false
+	}
+
+	// The numbers in the tzset string are added to local time to get UTC,
+	// but our offsets are added to UTC to get local time,
+	// so we negate the number we see here.
+	stdOffset = -stdOffset
+
+	if len(s) == 0 || s[0] == ',' {
+		// No daylight savings time.
+		return stdName, stdOffset, lastTxSec, omega, false, true
+	}
+
+	dstName, s, ok = tzsetName(s)
+	if ok {
+		if len(s) == 0 || s[0] == ',' {
+			dstOffset = stdOffset + secondsPerHour
+		} else {
+			dstOffset, s, ok = tzsetOffset(s)
+			dstOffset = -dstOffset // as with stdOffset, above
+		}
+	}
+	if !ok {
+		return "", 0, 0, 0, false, false
+	}
+
+	if len(s) == 0 {
+		// Default DST rules per tzcode.
+		s = ",M3.2.0,M11.1.0"
+	}
+	// The TZ definition does not mention ';' here but tzcode accepts it.
+	if s[0] != ',' && s[0] != ';' {
+		return "", 0, 0, 0, false, false
+	}
+	s = s[1:]
+
+	var startRule, endRule rule
+	startRule, s, ok = tzsetRule(s)
+	if !ok || len(s) == 0 || s[0] != ',' {
+		return "", 0, 0, 0, false, false
+	}
+	s = s[1:]
+	endRule, s, ok = tzsetRule(s)
+	if !ok || len(s) > 0 {
+		return "", 0, 0, 0, false, false
+	}
+
+	year, _, _, yday := absDate(uint64(sec+unixToInternal+internalToAbsolute), false)
+
+	ysec := int64(yday*secondsPerDay) + sec%secondsPerDay
+
+	// Compute start of year in seconds since Unix epoch.
+	d := daysSinceEpoch(year)
+	abs := int64(d * secondsPerDay)
+	abs += absoluteToInternal + internalToUnix
+
+	startSec := int64(tzruleTime(year, startRule, stdOffset))
+	endSec := int64(tzruleTime(year, endRule, dstOffset))
+	dstIsDST, stdIsDST := true, false
+	// Note: this is a flipping of "DST" and "STD" while retaining the labels
+	// This happens in southern hemispheres. The labelling here thus is a little
+	// inconsistent with the goal.
+	if endSec < startSec {
+		startSec, endSec = endSec, startSec
+		stdName, dstName = dstName, stdName
+		stdOffset, dstOffset = dstOffset, stdOffset
+		stdIsDST, dstIsDST = dstIsDST, stdIsDST
+	}
+
+	// The start and end values that we return are accurate
+	// close to a daylight savings transition, but are otherwise
+	// just the start and end of the year. That suffices for
+	// the only caller that cares, which is Date.
+	if ysec < startSec {
+		return stdName, stdOffset, abs, startSec + abs, stdIsDST, true
+	} else if ysec >= endSec {
+		return stdName, stdOffset, endSec + abs, abs + 365*secondsPerDay, stdIsDST, true
+	} else {
+		return dstName, dstOffset, startSec + abs, endSec + abs, dstIsDST, true
+	}
+}
+
+// tzsetName returns the timezone name at the start of the tzset string s,
+// and the remainder of s, and reports whether the parsing is OK.
+func tzsetName(s string) (string, string, bool) {
+	if len(s) == 0 {
+		return "", "", false
+	}
+	if s[0] != '<' {
+		for i, r := range s {
+			switch r {
+			case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ',', '-', '+':
+				if i < 3 {
+					return "", "", false
+				}
+				return s[:i], s[i:], true
+			}
+		}
+		if len(s) < 3 {
+			return "", "", false
+		}
+		return s, "", true
+	} else {
+		for i, r := range s {
+			if r == '>' {
+				return s[1:i], s[i+1:], true
+			}
+		}
+		return "", "", false
+	}
+}
+
+// tzsetOffset returns the timezone offset at the start of the tzset string s,
+// and the remainder of s, and reports whether the parsing is OK.
+// The timezone offset is returned as a number of seconds.
+func tzsetOffset(s string) (offset int, rest string, ok bool) {
+	if len(s) == 0 {
+		return 0, "", false
+	}
+	neg := false
+	if s[0] == '+' {
+		s = s[1:]
+	} else if s[0] == '-' {
+		s = s[1:]
+		neg = true
+	}
+
+	// The tzdata code permits values up to 24 * 7 here,
+	// although POSIX does not.
+	var hours int
+	hours, s, ok = tzsetNum(s, 0, 24*7)
+	if !ok {
+		return 0, "", false
+	}
+	off := hours * secondsPerHour
+	if len(s) == 0 || s[0] != ':' {
+		if neg {
+			off = -off
+		}
+		return off, s, true
+	}
+
+	var mins int
+	mins, s, ok = tzsetNum(s[1:], 0, 59)
+	if !ok {
+		return 0, "", false
+	}
+	off += mins * secondsPerMinute
+	if len(s) == 0 || s[0] != ':' {
+		if neg {
+			off = -off
+		}
+		return off, s, true
+	}
+
+	var secs int
+	secs, s, ok = tzsetNum(s[1:], 0, 59)
+	if !ok {
+		return 0, "", false
+	}
+	off += secs
+
+	if neg {
+		off = -off
+	}
+	return off, s, true
+}
+
+// ruleKind is the kinds of rules that can be seen in a tzset string.
+type ruleKind int
+
+const (
+	ruleJulian ruleKind = iota
+	ruleDOY
+	ruleMonthWeekDay
+)
+
+// rule is a rule read from a tzset string.
+type rule struct {
+	kind ruleKind
+	day  int
+	week int
+	mon  int
+	time int // transition time
+}
+
+// tzsetRule parses a rule from a tzset string.
+// It returns the rule, and the remainder of the string, and reports success.
+func tzsetRule(s string) (rule, string, bool) {
+	var r rule
+	if len(s) == 0 {
+		return rule{}, "", false
+	}
+	ok := false
+	if s[0] == 'J' {
+		var jday int
+		jday, s, ok = tzsetNum(s[1:], 1, 365)
+		if !ok {
+			return rule{}, "", false
+		}
+		r.kind = ruleJulian
+		r.day = jday
+	} else if s[0] == 'M' {
+		var mon int
+		mon, s, ok = tzsetNum(s[1:], 1, 12)
+		if !ok || len(s) == 0 || s[0] != '.' {
+			return rule{}, "", false
+
+		}
+		var week int
+		week, s, ok = tzsetNum(s[1:], 1, 5)
+		if !ok || len(s) == 0 || s[0] != '.' {
+			return rule{}, "", false
+		}
+		var day int
+		day, s, ok = tzsetNum(s[1:], 0, 6)
+		if !ok {
+			return rule{}, "", false
+		}
+		r.kind = ruleMonthWeekDay
+		r.day = day
+		r.week = week
+		r.mon = mon
+	} else {
+		var day int
+		day, s, ok = tzsetNum(s, 0, 365)
+		if !ok {
+			return rule{}, "", false
+		}
+		r.kind = ruleDOY
+		r.day = day
+	}
+
+	if len(s) == 0 || s[0] != '/' {
+		r.time = 2 * secondsPerHour // 2am is the default
+		return r, s, true
+	}
+
+	offset, s, ok := tzsetOffset(s[1:])
+	if !ok {
+		return rule{}, "", false
+	}
+	r.time = offset
+
+	return r, s, true
+}
+
+// tzsetNum parses a number from a tzset string.
+// It returns the number, and the remainder of the string, and reports success.
+// The number must be between min and max.
+func tzsetNum(s string, min, max int) (num int, rest string, ok bool) {
+	if len(s) == 0 {
+		return 0, "", false
+	}
+	num = 0
+	for i, r := range s {
+		if r < '0' || r > '9' {
+			if i == 0 || num < min {
+				return 0, "", false
+			}
+			return num, s[i:], true
+		}
+		num *= 10
+		num += int(r) - '0'
+		if num > max {
+			return 0, "", false
+		}
+	}
+	if num < min {
+		return 0, "", false
+	}
+	return num, "", true
+}
+
+// tzruleTime takes a year, a rule, and a timezone offset,
+// and returns the number of seconds since the start of the year
+// that the rule takes effect.
+func tzruleTime(year int, r rule, off int) int {
+	var s int
+	switch r.kind {
+	case ruleJulian:
+		s = (r.day - 1) * secondsPerDay
+		if isLeap(year) && r.day >= 60 {
+			s += secondsPerDay
+		}
+	case ruleDOY:
+		s = r.day * secondsPerDay
+	case ruleMonthWeekDay:
+		// Zeller's Congruence.
+		m1 := (r.mon+9)%12 + 1
+		yy0 := year
+		if r.mon <= 2 {
+			yy0--
+		}
+		yy1 := yy0 / 100
+		yy2 := yy0 % 100
+		dow := ((26*m1-2)/10 + 1 + yy2 + yy2/4 + yy1/4 - 2*yy1) % 7
+		if dow < 0 {
+			dow += 7
+		}
+		// Now dow is the day-of-week of the first day of r.mon.
+		// Get the day-of-month of the first "dow" day.
+		d := r.day - dow
+		if d < 0 {
+			d += 7
+		}
+		for i := 1; i < r.week; i++ {
+			if d+7 >= daysIn(Month(r.mon), year) {
+				break
+			}
+			d += 7
+		}
+		d += int(daysBefore[r.mon-1])
+		if isLeap(year) && r.mon > 2 {
+			d++
+		}
+		s = d * secondsPerDay
+	}
+
+	return s + r.time - off
+}
+
+// lookupName returns information about the time zone with
+// the given name (such as "EST") at the given pseudo-Unix time
+// (what the given time of day would be in UTC).
+func (l *Location) lookupName(name string, unix int64) (offset int, ok bool) {
+	l = l.get()
+
+	// First try for a zone with the right name that was actually
+	// in effect at the given time. (In Sydney, Australia, both standard
+	// and daylight-savings time are abbreviated "EST". Using the
+	// offset helps us pick the right one for the given time.
+	// It's not perfect: during the backward transition we might pick
+	// either one.)
+	for i := range l.zone {
+		zone := &l.zone[i]
+		if zone.name == name {
+			nam, offset, _, _, _ := l.lookup(unix - int64(zone.offset))
+			if nam == zone.name {
+				return offset, true
+			}
+		}
+	}
+
+	// Otherwise fall back to an ordinary name match.
+	for i := range l.zone {
+		zone := &l.zone[i]
+		if zone.name == name {
+			return zone.offset, true
+		}
+	}
+
+	// Otherwise, give up.
+	return
+}
+
+// NOTE(rsc): Eventually we will need to accept the POSIX TZ environment
+// syntax too, but I don't feel like implementing it today.
+
+var errLocation = errors.New("time: invalid location name")
+
+var zoneinfo *string
+var zoneinfoOnce sync.Once
+
+// LoadLocation returns the Location with the given name.
+//
+// If the name is "" or "UTC", LoadLocation returns UTC.
+// If the name is "Local", LoadLocation returns Local.
+//
+// Otherwise, the name is taken to be a location name corresponding to a file
+// in the IANA Time Zone database, such as "America/New_York".
+//
+// LoadLocation looks for the IANA Time Zone database in the following
+// locations in order:
+//
+//   - the directory or uncompressed zip file named by the ZONEINFO environment variable
+//   - on a Unix system, the system standard installation location
+//   - $GOROOT/lib/time/zoneinfo.zip
+//   - the time/tzdata package, if it was imported
+func LoadLocation(name string) (*Location, error) {
+	if name == "" || name == "UTC" {
+		return UTC, nil
+	}
+	if name == "Local" {
+		return Local, nil
+	}
+	if containsDotDot(name) || name[0] == '/' || name[0] == '\\' {
+		// No valid IANA Time Zone name contains a single dot,
+		// much less dot dot. Likewise, none begin with a slash.
+		return nil, errLocation
+	}
+	zoneinfoOnce.Do(func() {
+		env, _ := syscall.Getenv("ZONEINFO")
+		zoneinfo = &env
+	})
+	var firstErr error
+	if *zoneinfo != "" {
+		if zoneData, err := loadTzinfoFromDirOrZip(*zoneinfo, name); err == nil {
+			if z, err := LoadLocationFromTZData(name, zoneData); err == nil {
+				return z, nil
+			}
+			firstErr = err
+		} else if err != syscall.ENOENT {
+			firstErr = err
+		}
+	}
+	if z, err := loadLocation(name, platformZoneSources); err == nil {
+		return z, nil
+	} else if firstErr == nil {
+		firstErr = err
+	}
+	return nil, firstErr
+}
+
+// containsDotDot reports whether s contains "..".
+func containsDotDot(s string) bool {
+	if len(s) < 2 {
+		return false
+	}
+	for i := 0; i < len(s)-1; i++ {
+		if s[i] == '.' && s[i+1] == '.' {
+			return true
+		}
+	}
+	return false
+}
diff --git a/src/time/zoneinfo_abbrs_windows.go b/src/time/zoneinfo_abbrs_windows.go
new file mode 100644
index 0000000..2783174
--- /dev/null
+++ b/src/time/zoneinfo_abbrs_windows.go
@@ -0,0 +1,155 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by genzabbrs.go; DO NOT EDIT.
+// Based on information from https://raw.githubusercontent.com/unicode-org/cldr/main/common/supplemental/windowsZones.xml
+
+package time
+
+type abbr struct {
+	std string
+	dst string
+}
+
+var abbrs = map[string]abbr{
+	"Egypt Standard Time":             {"EET", "EEST"},    // Africa/Cairo
+	"Morocco Standard Time":           {"+00", "+01"},     // Africa/Casablanca
+	"South Africa Standard Time":      {"SAST", "SAST"},   // Africa/Johannesburg
+	"South Sudan Standard Time":       {"CAT", "CAT"},     // Africa/Juba
+	"Sudan Standard Time":             {"CAT", "CAT"},     // Africa/Khartoum
+	"W. Central Africa Standard Time": {"WAT", "WAT"},     // Africa/Lagos
+	"E. Africa Standard Time":         {"EAT", "EAT"},     // Africa/Nairobi
+	"Sao Tome Standard Time":          {"GMT", "GMT"},     // Africa/Sao_Tome
+	"Libya Standard Time":             {"EET", "EET"},     // Africa/Tripoli
+	"Namibia Standard Time":           {"CAT", "CAT"},     // Africa/Windhoek
+	"Aleutian Standard Time":          {"HST", "HDT"},     // America/Adak
+	"Alaskan Standard Time":           {"AKST", "AKDT"},   // America/Anchorage
+	"Tocantins Standard Time":         {"-03", "-03"},     // America/Araguaina
+	"Paraguay Standard Time":          {"-04", "-03"},     // America/Asuncion
+	"Bahia Standard Time":             {"-03", "-03"},     // America/Bahia
+	"SA Pacific Standard Time":        {"-05", "-05"},     // America/Bogota
+	"Argentina Standard Time":         {"-03", "-03"},     // America/Buenos_Aires
+	"Eastern Standard Time (Mexico)":  {"EST", "EST"},     // America/Cancun
+	"Venezuela Standard Time":         {"-04", "-04"},     // America/Caracas
+	"SA Eastern Standard Time":        {"-03", "-03"},     // America/Cayenne
+	"Central Standard Time":           {"CST", "CDT"},     // America/Chicago
+	"Central Brazilian Standard Time": {"-04", "-04"},     // America/Cuiaba
+	"Mountain Standard Time":          {"MST", "MDT"},     // America/Denver
+	"Greenland Standard Time":         {"-03", "-02"},     // America/Godthab
+	"Turks And Caicos Standard Time":  {"EST", "EDT"},     // America/Grand_Turk
+	"Central America Standard Time":   {"CST", "CST"},     // America/Guatemala
+	"Atlantic Standard Time":          {"AST", "ADT"},     // America/Halifax
+	"Cuba Standard Time":              {"CST", "CDT"},     // America/Havana
+	"US Eastern Standard Time":        {"EST", "EDT"},     // America/Indianapolis
+	"SA Western Standard Time":        {"-04", "-04"},     // America/La_Paz
+	"Pacific Standard Time":           {"PST", "PDT"},     // America/Los_Angeles
+	"Mountain Standard Time (Mexico)": {"MST", "MST"},     // America/Mazatlan
+	"Central Standard Time (Mexico)":  {"CST", "CST"},     // America/Mexico_City
+	"Saint Pierre Standard Time":      {"-03", "-02"},     // America/Miquelon
+	"Montevideo Standard Time":        {"-03", "-03"},     // America/Montevideo
+	"Eastern Standard Time":           {"EST", "EDT"},     // America/New_York
+	"US Mountain Standard Time":       {"MST", "MST"},     // America/Phoenix
+	"Haiti Standard Time":             {"EST", "EDT"},     // America/Port-au-Prince
+	"Magallanes Standard Time":        {"-03", "-03"},     // America/Punta_Arenas
+	"Canada Central Standard Time":    {"CST", "CST"},     // America/Regina
+	"Pacific SA Standard Time":        {"-04", "-03"},     // America/Santiago
+	"E. South America Standard Time":  {"-03", "-03"},     // America/Sao_Paulo
+	"Newfoundland Standard Time":      {"NST", "NDT"},     // America/St_Johns
+	"Pacific Standard Time (Mexico)":  {"PST", "PDT"},     // America/Tijuana
+	"Yukon Standard Time":             {"MST", "MST"},     // America/Whitehorse
+	"Central Asia Standard Time":      {"+06", "+06"},     // Asia/Almaty
+	"Jordan Standard Time":            {"+03", "+03"},     // Asia/Amman
+	"Arabic Standard Time":            {"+03", "+03"},     // Asia/Baghdad
+	"Azerbaijan Standard Time":        {"+04", "+04"},     // Asia/Baku
+	"SE Asia Standard Time":           {"+07", "+07"},     // Asia/Bangkok
+	"Altai Standard Time":             {"+07", "+07"},     // Asia/Barnaul
+	"Middle East Standard Time":       {"EET", "EEST"},    // Asia/Beirut
+	"India Standard Time":             {"IST", "IST"},     // Asia/Calcutta
+	"Transbaikal Standard Time":       {"+09", "+09"},     // Asia/Chita
+	"Sri Lanka Standard Time":         {"+0530", "+0530"}, // Asia/Colombo
+	"Syria Standard Time":             {"+03", "+03"},     // Asia/Damascus
+	"Bangladesh Standard Time":        {"+06", "+06"},     // Asia/Dhaka
+	"Arabian Standard Time":           {"+04", "+04"},     // Asia/Dubai
+	"West Bank Standard Time":         {"EET", "EEST"},    // Asia/Hebron
+	"W. Mongolia Standard Time":       {"+07", "+07"},     // Asia/Hovd
+	"North Asia East Standard Time":   {"+08", "+08"},     // Asia/Irkutsk
+	"Israel Standard Time":            {"IST", "IDT"},     // Asia/Jerusalem
+	"Afghanistan Standard Time":       {"+0430", "+0430"}, // Asia/Kabul
+	"Russia Time Zone 11":             {"+12", "+12"},     // Asia/Kamchatka
+	"Pakistan Standard Time":          {"PKT", "PKT"},     // Asia/Karachi
+	"Nepal Standard Time":             {"+0545", "+0545"}, // Asia/Katmandu
+	"North Asia Standard Time":        {"+07", "+07"},     // Asia/Krasnoyarsk
+	"Magadan Standard Time":           {"+11", "+11"},     // Asia/Magadan
+	"N. Central Asia Standard Time":   {"+07", "+07"},     // Asia/Novosibirsk
+	"Omsk Standard Time":              {"+06", "+06"},     // Asia/Omsk
+	"North Korea Standard Time":       {"KST", "KST"},     // Asia/Pyongyang
+	"Qyzylorda Standard Time":         {"+05", "+05"},     // Asia/Qyzylorda
+	"Myanmar Standard Time":           {"+0630", "+0630"}, // Asia/Rangoon
+	"Arab Standard Time":              {"+03", "+03"},     // Asia/Riyadh
+	"Sakhalin Standard Time":          {"+11", "+11"},     // Asia/Sakhalin
+	"Korea Standard Time":             {"KST", "KST"},     // Asia/Seoul
+	"China Standard Time":             {"CST", "CST"},     // Asia/Shanghai
+	"Singapore Standard Time":         {"+08", "+08"},     // Asia/Singapore
+	"Russia Time Zone 10":             {"+11", "+11"},     // Asia/Srednekolymsk
+	"Taipei Standard Time":            {"CST", "CST"},     // Asia/Taipei
+	"West Asia Standard Time":         {"+05", "+05"},     // Asia/Tashkent
+	"Georgian Standard Time":          {"+04", "+04"},     // Asia/Tbilisi
+	"Iran Standard Time":              {"+0330", "+0330"}, // Asia/Tehran
+	"Tokyo Standard Time":             {"JST", "JST"},     // Asia/Tokyo
+	"Tomsk Standard Time":             {"+07", "+07"},     // Asia/Tomsk
+	"Ulaanbaatar Standard Time":       {"+08", "+08"},     // Asia/Ulaanbaatar
+	"Vladivostok Standard Time":       {"+10", "+10"},     // Asia/Vladivostok
+	"Yakutsk Standard Time":           {"+09", "+09"},     // Asia/Yakutsk
+	"Ekaterinburg Standard Time":      {"+05", "+05"},     // Asia/Yekaterinburg
+	"Caucasus Standard Time":          {"+04", "+04"},     // Asia/Yerevan
+	"Azores Standard Time":            {"-01", "+00"},     // Atlantic/Azores
+	"Cape Verde Standard Time":        {"-01", "-01"},     // Atlantic/Cape_Verde
+	"Greenwich Standard Time":         {"GMT", "GMT"},     // Atlantic/Reykjavik
+	"Cen. Australia Standard Time":    {"ACST", "ACDT"},   // Australia/Adelaide
+	"E. Australia Standard Time":      {"AEST", "AEST"},   // Australia/Brisbane
+	"AUS Central Standard Time":       {"ACST", "ACST"},   // Australia/Darwin
+	"Aus Central W. Standard Time":    {"+0845", "+0845"}, // Australia/Eucla
+	"Tasmania Standard Time":          {"AEST", "AEDT"},   // Australia/Hobart
+	"Lord Howe Standard Time":         {"+1030", "+11"},   // Australia/Lord_Howe
+	"W. Australia Standard Time":      {"AWST", "AWST"},   // Australia/Perth
+	"AUS Eastern Standard Time":       {"AEST", "AEDT"},   // Australia/Sydney
+	"UTC-11":                          {"-11", "-11"},     // Etc/GMT+11
+	"Dateline Standard Time":          {"-12", "-12"},     // Etc/GMT+12
+	"UTC-02":                          {"-02", "-02"},     // Etc/GMT+2
+	"UTC-08":                          {"-08", "-08"},     // Etc/GMT+8
+	"UTC-09":                          {"-09", "-09"},     // Etc/GMT+9
+	"UTC+12":                          {"+12", "+12"},     // Etc/GMT-12
+	"UTC+13":                          {"+13", "+13"},     // Etc/GMT-13
+	"UTC":                             {"UTC", "UTC"},     // Etc/UTC
+	"Astrakhan Standard Time":         {"+04", "+04"},     // Europe/Astrakhan
+	"W. Europe Standard Time":         {"CET", "CEST"},    // Europe/Berlin
+	"GTB Standard Time":               {"EET", "EEST"},    // Europe/Bucharest
+	"Central Europe Standard Time":    {"CET", "CEST"},    // Europe/Budapest
+	"E. Europe Standard Time":         {"EET", "EEST"},    // Europe/Chisinau
+	"Turkey Standard Time":            {"+03", "+03"},     // Europe/Istanbul
+	"Kaliningrad Standard Time":       {"EET", "EET"},     // Europe/Kaliningrad
+	"FLE Standard Time":               {"EET", "EEST"},    // Europe/Kiev
+	"GMT Standard Time":               {"GMT", "BST"},     // Europe/London
+	"Belarus Standard Time":           {"+03", "+03"},     // Europe/Minsk
+	"Russian Standard Time":           {"MSK", "MSK"},     // Europe/Moscow
+	"Romance Standard Time":           {"CET", "CEST"},    // Europe/Paris
+	"Russia Time Zone 3":              {"+04", "+04"},     // Europe/Samara
+	"Saratov Standard Time":           {"+04", "+04"},     // Europe/Saratov
+	"Volgograd Standard Time":         {"MSK", "MSK"},     // Europe/Volgograd
+	"Central European Standard Time":  {"CET", "CEST"},    // Europe/Warsaw
+	"Mauritius Standard Time":         {"+04", "+04"},     // Indian/Mauritius
+	"Samoa Standard Time":             {"+13", "+13"},     // Pacific/Apia
+	"New Zealand Standard Time":       {"NZST", "NZDT"},   // Pacific/Auckland
+	"Bougainville Standard Time":      {"+11", "+11"},     // Pacific/Bougainville
+	"Chatham Islands Standard Time":   {"+1245", "+1345"}, // Pacific/Chatham
+	"Easter Island Standard Time":     {"-06", "-05"},     // Pacific/Easter
+	"Fiji Standard Time":              {"+12", "+12"},     // Pacific/Fiji
+	"Central Pacific Standard Time":   {"+11", "+11"},     // Pacific/Guadalcanal
+	"Hawaiian Standard Time":          {"HST", "HST"},     // Pacific/Honolulu
+	"Line Islands Standard Time":      {"+14", "+14"},     // Pacific/Kiritimati
+	"Marquesas Standard Time":         {"-0930", "-0930"}, // Pacific/Marquesas
+	"Norfolk Standard Time":           {"+11", "+12"},     // Pacific/Norfolk
+	"West Pacific Standard Time":      {"+10", "+10"},     // Pacific/Port_Moresby
+	"Tonga Standard Time":             {"+13", "+13"},     // Pacific/Tongatapu
+}
diff --git a/src/time/zoneinfo_android.go b/src/time/zoneinfo_android.go
new file mode 100644
index 0000000..e4f688d
--- /dev/null
+++ b/src/time/zoneinfo_android.go
@@ -0,0 +1,87 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Parse the "tzdata" packed timezone file used on Android.
+// The format is lifted from ZoneInfoDB.java and ZoneInfo.java in
+// java/libcore/util in the AOSP.
+
+package time
+
+import (
+	"errors"
+	"syscall"
+)
+
+var platformZoneSources = []string{
+	"/system/usr/share/zoneinfo/tzdata",
+	"/data/misc/zoneinfo/current/tzdata",
+}
+
+func initLocal() {
+	// TODO(elias.naur): getprop persist.sys.timezone
+	localLoc = *UTC
+}
+
+func init() {
+	loadTzinfoFromTzdata = androidLoadTzinfoFromTzdata
+}
+
+var allowGorootSource = true
+
+func gorootZoneSource(goroot string) (string, bool) {
+	if goroot == "" || !allowGorootSource {
+		return "", false
+	}
+	return goroot + "/lib/time/zoneinfo.zip", true
+}
+
+func androidLoadTzinfoFromTzdata(file, name string) ([]byte, error) {
+	const (
+		headersize = 12 + 3*4
+		namesize   = 40
+		entrysize  = namesize + 3*4
+	)
+	if len(name) > namesize {
+		return nil, errors.New(name + " is longer than the maximum zone name length (40 bytes)")
+	}
+	fd, err := open(file)
+	if err != nil {
+		return nil, err
+	}
+	defer closefd(fd)
+
+	buf := make([]byte, headersize)
+	if err := preadn(fd, buf, 0); err != nil {
+		return nil, errors.New("corrupt tzdata file " + file)
+	}
+	d := dataIO{buf, false}
+	if magic := d.read(6); string(magic) != "tzdata" {
+		return nil, errors.New("corrupt tzdata file " + file)
+	}
+	d = dataIO{buf[12:], false}
+	indexOff, _ := d.big4()
+	dataOff, _ := d.big4()
+	indexSize := dataOff - indexOff
+	entrycount := indexSize / entrysize
+	buf = make([]byte, indexSize)
+	if err := preadn(fd, buf, int(indexOff)); err != nil {
+		return nil, errors.New("corrupt tzdata file " + file)
+	}
+	for i := 0; i < int(entrycount); i++ {
+		entry := buf[i*entrysize : (i+1)*entrysize]
+		// len(name) <= namesize is checked at function entry
+		if string(entry[:len(name)]) != name {
+			continue
+		}
+		d := dataIO{entry[namesize:], false}
+		off, _ := d.big4()
+		size, _ := d.big4()
+		buf := make([]byte, size)
+		if err := preadn(fd, buf, int(off+dataOff)); err != nil {
+			return nil, errors.New("corrupt tzdata file " + file)
+		}
+		return buf, nil
+	}
+	return nil, syscall.ENOENT
+}
diff --git a/src/time/zoneinfo_android_test.go b/src/time/zoneinfo_android_test.go
new file mode 100644
index 0000000..f8bd7f7
--- /dev/null
+++ b/src/time/zoneinfo_android_test.go
@@ -0,0 +1,18 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"testing"
+	. "time"
+)
+
+func TestAndroidTzdata(t *testing.T) {
+	undo := ForceAndroidTzdataForTest()
+	defer undo()
+	if _, err := LoadLocation("America/Los_Angeles"); err != nil {
+		t.Error(err)
+	}
+}
diff --git a/src/time/zoneinfo_goroot.go b/src/time/zoneinfo_goroot.go
new file mode 100644
index 0000000..92bdcf4
--- /dev/null
+++ b/src/time/zoneinfo_goroot.go
@@ -0,0 +1,14 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !ios && !android
+
+package time
+
+func gorootZoneSource(goroot string) (string, bool) {
+	if goroot == "" {
+		return "", false
+	}
+	return goroot + "/lib/time/zoneinfo.zip", true
+}
diff --git a/src/time/zoneinfo_ios.go b/src/time/zoneinfo_ios.go
new file mode 100644
index 0000000..d6ad073
--- /dev/null
+++ b/src/time/zoneinfo_ios.go
@@ -0,0 +1,45 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ios
+
+package time
+
+import (
+	"syscall"
+)
+
+var platformZoneSources []string // none on iOS
+
+func gorootZoneSource(goroot string) (string, bool) {
+	// The working directory at initialization is the root of the
+	// app bundle: "/private/.../bundlename.app". That's where we
+	// keep zoneinfo.zip for tethered iOS builds.
+	// For self-hosted iOS builds, the zoneinfo.zip is in GOROOT.
+	var roots []string
+	if goroot != "" {
+		roots = append(roots, goroot+"/lib/time")
+	}
+	wd, err := syscall.Getwd()
+	if err == nil {
+		roots = append(roots, wd)
+	}
+	for _, r := range roots {
+		var st syscall.Stat_t
+		fd, err := syscall.Open(r, syscall.O_RDONLY, 0)
+		if err != nil {
+			continue
+		}
+		defer syscall.Close(fd)
+		if err := syscall.Fstat(fd, &st); err == nil {
+			return r + "/zoneinfo.zip", true
+		}
+	}
+	return "", false
+}
+
+func initLocal() {
+	// TODO(crawshaw): [NSTimeZone localTimeZone]
+	localLoc = *UTC
+}
diff --git a/src/time/zoneinfo_js.go b/src/time/zoneinfo_js.go
new file mode 100644
index 0000000..8da34a2
--- /dev/null
+++ b/src/time/zoneinfo_js.go
@@ -0,0 +1,45 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build js && wasm
+
+package time
+
+import (
+	"internal/itoa"
+	"syscall/js"
+)
+
+var platformZoneSources = []string{
+	"/usr/share/zoneinfo/",
+	"/usr/share/lib/zoneinfo/",
+	"/usr/lib/locale/TZ/",
+}
+
+func initLocal() {
+	localLoc.name = "Local"
+
+	z := zone{}
+	d := js.Global().Get("Date").New()
+	offset := d.Call("getTimezoneOffset").Int() * -1
+	z.offset = offset * 60
+	// According to https://tc39.github.io/ecma262/#sec-timezoneestring,
+	// the timezone name from (new Date()).toTimeString() is an implementation-dependent
+	// result, and in Google Chrome, it gives the fully expanded name rather than
+	// the abbreviation.
+	// Hence, we construct the name from the offset.
+	z.name = "UTC"
+	if offset < 0 {
+		z.name += "-"
+		offset *= -1
+	} else {
+		z.name += "+"
+	}
+	z.name += itoa.Itoa(offset / 60)
+	min := offset % 60
+	if min != 0 {
+		z.name += ":" + itoa.Itoa(min)
+	}
+	localLoc.zone = []zone{z}
+}
diff --git a/src/time/zoneinfo_plan9.go b/src/time/zoneinfo_plan9.go
new file mode 100644
index 0000000..d13b623
--- /dev/null
+++ b/src/time/zoneinfo_plan9.go
@@ -0,0 +1,139 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Parse Plan 9 timezone(2) files.
+
+package time
+
+import (
+	"syscall"
+)
+
+var platformZoneSources []string // none on Plan 9
+
+func isSpace(r rune) bool {
+	return r == ' ' || r == '\t' || r == '\n'
+}
+
+// Copied from strings to avoid a dependency.
+func fields(s string) []string {
+	// First count the fields.
+	n := 0
+	inField := false
+	for _, rune := range s {
+		wasInField := inField
+		inField = !isSpace(rune)
+		if inField && !wasInField {
+			n++
+		}
+	}
+
+	// Now create them.
+	a := make([]string, n)
+	na := 0
+	fieldStart := -1 // Set to -1 when looking for start of field.
+	for i, rune := range s {
+		if isSpace(rune) {
+			if fieldStart >= 0 {
+				a[na] = s[fieldStart:i]
+				na++
+				fieldStart = -1
+			}
+		} else if fieldStart == -1 {
+			fieldStart = i
+		}
+	}
+	if fieldStart >= 0 { // Last field might end at EOF.
+		a[na] = s[fieldStart:]
+	}
+	return a
+}
+
+func loadZoneDataPlan9(s string) (l *Location, err error) {
+	f := fields(s)
+	if len(f) < 4 {
+		if len(f) == 2 && f[0] == "GMT" {
+			return UTC, nil
+		}
+		return nil, errBadData
+	}
+
+	var zones [2]zone
+
+	// standard timezone offset
+	o, err := atoi(f[1])
+	if err != nil {
+		return nil, errBadData
+	}
+	zones[0] = zone{name: f[0], offset: o, isDST: false}
+
+	// alternate timezone offset
+	o, err = atoi(f[3])
+	if err != nil {
+		return nil, errBadData
+	}
+	zones[1] = zone{name: f[2], offset: o, isDST: true}
+
+	// transition time pairs
+	var tx []zoneTrans
+	f = f[4:]
+	for i := 0; i < len(f); i++ {
+		zi := 0
+		if i%2 == 0 {
+			zi = 1
+		}
+		t, err := atoi(f[i])
+		if err != nil {
+			return nil, errBadData
+		}
+		t -= zones[0].offset
+		tx = append(tx, zoneTrans{when: int64(t), index: uint8(zi)})
+	}
+
+	// Committed to succeed.
+	l = &Location{zone: zones[:], tx: tx}
+
+	// Fill in the cache with information about right now,
+	// since that will be the most common lookup.
+	sec, _, _ := now()
+	for i := range tx {
+		if tx[i].when <= sec && (i+1 == len(tx) || sec < tx[i+1].when) {
+			l.cacheStart = tx[i].when
+			l.cacheEnd = omega
+			if i+1 < len(tx) {
+				l.cacheEnd = tx[i+1].when
+			}
+			l.cacheZone = &l.zone[tx[i].index]
+		}
+	}
+
+	return l, nil
+}
+
+func loadZoneFilePlan9(name string) (*Location, error) {
+	b, err := readFile(name)
+	if err != nil {
+		return nil, err
+	}
+	return loadZoneDataPlan9(string(b))
+}
+
+func initLocal() {
+	t, ok := syscall.Getenv("timezone")
+	if ok {
+		if z, err := loadZoneDataPlan9(t); err == nil {
+			localLoc = *z
+			return
+		}
+	} else {
+		if z, err := loadZoneFilePlan9("/adm/timezone/local"); err == nil {
+			localLoc = *z
+			localLoc.name = "Local"
+			return
+		}
+	}
+
+	// Fall back to UTC.
+	localLoc.name = "UTC"
+}
diff --git a/src/time/zoneinfo_read.go b/src/time/zoneinfo_read.go
new file mode 100644
index 0000000..4d0e47d
--- /dev/null
+++ b/src/time/zoneinfo_read.go
@@ -0,0 +1,597 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Parse "zoneinfo" time zone file.
+// This is a fairly standard file format used on OS X, Linux, BSD, Sun, and others.
+// See tzfile(5), https://en.wikipedia.org/wiki/Zoneinfo,
+// and ftp://munnari.oz.au/pub/oldtz/
+
+package time
+
+import (
+	"errors"
+	"runtime"
+	"syscall"
+)
+
+// registerLoadFromEmbeddedTZData is called by the time/tzdata package,
+// if it is imported.
+func registerLoadFromEmbeddedTZData(f func(string) (string, error)) {
+	loadFromEmbeddedTZData = f
+}
+
+// loadFromEmbeddedTZData is used to load a specific tzdata file
+// from tzdata information embedded in the binary itself.
+// This is set when the time/tzdata package is imported,
+// via registerLoadFromEmbeddedTzdata.
+var loadFromEmbeddedTZData func(zipname string) (string, error)
+
+// maxFileSize is the max permitted size of files read by readFile.
+// As reference, the zoneinfo.zip distributed by Go is ~350 KB,
+// so 10MB is overkill.
+const maxFileSize = 10 << 20
+
+type fileSizeError string
+
+func (f fileSizeError) Error() string {
+	return "time: file " + string(f) + " is too large"
+}
+
+// Copies of io.Seek* constants to avoid importing "io":
+const (
+	seekStart   = 0
+	seekCurrent = 1
+	seekEnd     = 2
+)
+
+// Simple I/O interface to binary blob of data.
+type dataIO struct {
+	p     []byte
+	error bool
+}
+
+func (d *dataIO) read(n int) []byte {
+	if len(d.p) < n {
+		d.p = nil
+		d.error = true
+		return nil
+	}
+	p := d.p[0:n]
+	d.p = d.p[n:]
+	return p
+}
+
+func (d *dataIO) big4() (n uint32, ok bool) {
+	p := d.read(4)
+	if len(p) < 4 {
+		d.error = true
+		return 0, false
+	}
+	return uint32(p[3]) | uint32(p[2])<<8 | uint32(p[1])<<16 | uint32(p[0])<<24, true
+}
+
+func (d *dataIO) big8() (n uint64, ok bool) {
+	n1, ok1 := d.big4()
+	n2, ok2 := d.big4()
+	if !ok1 || !ok2 {
+		d.error = true
+		return 0, false
+	}
+	return (uint64(n1) << 32) | uint64(n2), true
+}
+
+func (d *dataIO) byte() (n byte, ok bool) {
+	p := d.read(1)
+	if len(p) < 1 {
+		d.error = true
+		return 0, false
+	}
+	return p[0], true
+}
+
+// read returns the read of the data in the buffer.
+func (d *dataIO) rest() []byte {
+	r := d.p
+	d.p = nil
+	return r
+}
+
+// Make a string by stopping at the first NUL
+func byteString(p []byte) string {
+	for i := 0; i < len(p); i++ {
+		if p[i] == 0 {
+			return string(p[0:i])
+		}
+	}
+	return string(p)
+}
+
+var errBadData = errors.New("malformed time zone information")
+
+// LoadLocationFromTZData returns a Location with the given name
+// initialized from the IANA Time Zone database-formatted data.
+// The data should be in the format of a standard IANA time zone file
+// (for example, the content of /etc/localtime on Unix systems).
+func LoadLocationFromTZData(name string, data []byte) (*Location, error) {
+	d := dataIO{data, false}
+
+	// 4-byte magic "TZif"
+	if magic := d.read(4); string(magic) != "TZif" {
+		return nil, errBadData
+	}
+
+	// 1-byte version, then 15 bytes of padding
+	var version int
+	var p []byte
+	if p = d.read(16); len(p) != 16 {
+		return nil, errBadData
+	} else {
+		switch p[0] {
+		case 0:
+			version = 1
+		case '2':
+			version = 2
+		case '3':
+			version = 3
+		default:
+			return nil, errBadData
+		}
+	}
+
+	// six big-endian 32-bit integers:
+	//	number of UTC/local indicators
+	//	number of standard/wall indicators
+	//	number of leap seconds
+	//	number of transition times
+	//	number of local time zones
+	//	number of characters of time zone abbrev strings
+	const (
+		NUTCLocal = iota
+		NStdWall
+		NLeap
+		NTime
+		NZone
+		NChar
+	)
+	var n [6]int
+	for i := 0; i < 6; i++ {
+		nn, ok := d.big4()
+		if !ok {
+			return nil, errBadData
+		}
+		if uint32(int(nn)) != nn {
+			return nil, errBadData
+		}
+		n[i] = int(nn)
+	}
+
+	// If we have version 2 or 3, then the data is first written out
+	// in a 32-bit format, then written out again in a 64-bit format.
+	// Skip the 32-bit format and read the 64-bit one, as it can
+	// describe a broader range of dates.
+
+	is64 := false
+	if version > 1 {
+		// Skip the 32-bit data.
+		skip := n[NTime]*4 +
+			n[NTime] +
+			n[NZone]*6 +
+			n[NChar] +
+			n[NLeap]*8 +
+			n[NStdWall] +
+			n[NUTCLocal]
+		// Skip the version 2 header that we just read.
+		skip += 4 + 16
+		d.read(skip)
+
+		is64 = true
+
+		// Read the counts again, they can differ.
+		for i := 0; i < 6; i++ {
+			nn, ok := d.big4()
+			if !ok {
+				return nil, errBadData
+			}
+			if uint32(int(nn)) != nn {
+				return nil, errBadData
+			}
+			n[i] = int(nn)
+		}
+	}
+
+	size := 4
+	if is64 {
+		size = 8
+	}
+
+	// Transition times.
+	txtimes := dataIO{d.read(n[NTime] * size), false}
+
+	// Time zone indices for transition times.
+	txzones := d.read(n[NTime])
+
+	// Zone info structures
+	zonedata := dataIO{d.read(n[NZone] * 6), false}
+
+	// Time zone abbreviations.
+	abbrev := d.read(n[NChar])
+
+	// Leap-second time pairs
+	d.read(n[NLeap] * (size + 4))
+
+	// Whether tx times associated with local time types
+	// are specified as standard time or wall time.
+	isstd := d.read(n[NStdWall])
+
+	// Whether tx times associated with local time types
+	// are specified as UTC or local time.
+	isutc := d.read(n[NUTCLocal])
+
+	if d.error { // ran out of data
+		return nil, errBadData
+	}
+
+	var extend string
+	rest := d.rest()
+	if len(rest) > 2 && rest[0] == '\n' && rest[len(rest)-1] == '\n' {
+		extend = string(rest[1 : len(rest)-1])
+	}
+
+	// Now we can build up a useful data structure.
+	// First the zone information.
+	//	utcoff[4] isdst[1] nameindex[1]
+	nzone := n[NZone]
+	if nzone == 0 {
+		// Reject tzdata files with no zones. There's nothing useful in them.
+		// This also avoids a panic later when we add and then use a fake transition (golang.org/issue/29437).
+		return nil, errBadData
+	}
+	zones := make([]zone, nzone)
+	for i := range zones {
+		var ok bool
+		var n uint32
+		if n, ok = zonedata.big4(); !ok {
+			return nil, errBadData
+		}
+		if uint32(int(n)) != n {
+			return nil, errBadData
+		}
+		zones[i].offset = int(int32(n))
+		var b byte
+		if b, ok = zonedata.byte(); !ok {
+			return nil, errBadData
+		}
+		zones[i].isDST = b != 0
+		if b, ok = zonedata.byte(); !ok || int(b) >= len(abbrev) {
+			return nil, errBadData
+		}
+		zones[i].name = byteString(abbrev[b:])
+		if runtime.GOOS == "aix" && len(name) > 8 && (name[:8] == "Etc/GMT+" || name[:8] == "Etc/GMT-") {
+			// There is a bug with AIX 7.2 TL 0 with files in Etc,
+			// GMT+1 will return GMT-1 instead of GMT+1 or -01.
+			if name != "Etc/GMT+0" {
+				// GMT+0 is OK
+				zones[i].name = name[4:]
+			}
+		}
+	}
+
+	// Now the transition time info.
+	tx := make([]zoneTrans, n[NTime])
+	for i := range tx {
+		var n int64
+		if !is64 {
+			if n4, ok := txtimes.big4(); !ok {
+				return nil, errBadData
+			} else {
+				n = int64(int32(n4))
+			}
+		} else {
+			if n8, ok := txtimes.big8(); !ok {
+				return nil, errBadData
+			} else {
+				n = int64(n8)
+			}
+		}
+		tx[i].when = n
+		if int(txzones[i]) >= len(zones) {
+			return nil, errBadData
+		}
+		tx[i].index = txzones[i]
+		if i < len(isstd) {
+			tx[i].isstd = isstd[i] != 0
+		}
+		if i < len(isutc) {
+			tx[i].isutc = isutc[i] != 0
+		}
+	}
+
+	if len(tx) == 0 {
+		// Build fake transition to cover all time.
+		// This happens in fixed locations like "Etc/GMT0".
+		tx = append(tx, zoneTrans{when: alpha, index: 0})
+	}
+
+	// Committed to succeed.
+	l := &Location{zone: zones, tx: tx, name: name, extend: extend}
+
+	// Fill in the cache with information about right now,
+	// since that will be the most common lookup.
+	sec, _, _ := now()
+	for i := range tx {
+		if tx[i].when <= sec && (i+1 == len(tx) || sec < tx[i+1].when) {
+			l.cacheStart = tx[i].when
+			l.cacheEnd = omega
+			l.cacheZone = &l.zone[tx[i].index]
+			if i+1 < len(tx) {
+				l.cacheEnd = tx[i+1].when
+			} else if l.extend != "" {
+				// If we're at the end of the known zone transitions,
+				// try the extend string.
+				if name, offset, estart, eend, isDST, ok := tzset(l.extend, l.cacheStart, sec); ok {
+					l.cacheStart = estart
+					l.cacheEnd = eend
+					// Find the zone that is returned by tzset to avoid allocation if possible.
+					if zoneIdx := findZone(l.zone, name, offset, isDST); zoneIdx != -1 {
+						l.cacheZone = &l.zone[zoneIdx]
+					} else {
+						l.cacheZone = &zone{
+							name:   name,
+							offset: offset,
+							isDST:  isDST,
+						}
+					}
+				}
+			}
+			break
+		}
+	}
+
+	return l, nil
+}
+
+func findZone(zones []zone, name string, offset int, isDST bool) int {
+	for i, z := range zones {
+		if z.name == name && z.offset == offset && z.isDST == isDST {
+			return i
+		}
+	}
+	return -1
+}
+
+// loadTzinfoFromDirOrZip returns the contents of the file with the given name
+// in dir. dir can either be an uncompressed zip file, or a directory.
+func loadTzinfoFromDirOrZip(dir, name string) ([]byte, error) {
+	if len(dir) > 4 && dir[len(dir)-4:] == ".zip" {
+		return loadTzinfoFromZip(dir, name)
+	}
+	if dir != "" {
+		name = dir + "/" + name
+	}
+	return readFile(name)
+}
+
+// There are 500+ zoneinfo files. Rather than distribute them all
+// individually, we ship them in an uncompressed zip file.
+// Used this way, the zip file format serves as a commonly readable
+// container for the individual small files. We choose zip over tar
+// because zip files have a contiguous table of contents, making
+// individual file lookups faster, and because the per-file overhead
+// in a zip file is considerably less than tar's 512 bytes.
+
+// get4 returns the little-endian 32-bit value in b.
+func get4(b []byte) int {
+	if len(b) < 4 {
+		return 0
+	}
+	return int(b[0]) | int(b[1])<<8 | int(b[2])<<16 | int(b[3])<<24
+}
+
+// get2 returns the little-endian 16-bit value in b.
+func get2(b []byte) int {
+	if len(b) < 2 {
+		return 0
+	}
+	return int(b[0]) | int(b[1])<<8
+}
+
+// loadTzinfoFromZip returns the contents of the file with the given name
+// in the given uncompressed zip file.
+func loadTzinfoFromZip(zipfile, name string) ([]byte, error) {
+	fd, err := open(zipfile)
+	if err != nil {
+		return nil, err
+	}
+	defer closefd(fd)
+
+	const (
+		zecheader = 0x06054b50
+		zcheader  = 0x02014b50
+		ztailsize = 22
+
+		zheadersize = 30
+		zheader     = 0x04034b50
+	)
+
+	buf := make([]byte, ztailsize)
+	if err := preadn(fd, buf, -ztailsize); err != nil || get4(buf) != zecheader {
+		return nil, errors.New("corrupt zip file " + zipfile)
+	}
+	n := get2(buf[10:])
+	size := get4(buf[12:])
+	off := get4(buf[16:])
+
+	buf = make([]byte, size)
+	if err := preadn(fd, buf, off); err != nil {
+		return nil, errors.New("corrupt zip file " + zipfile)
+	}
+
+	for i := 0; i < n; i++ {
+		// zip entry layout:
+		//	0	magic[4]
+		//	4	madevers[1]
+		//	5	madeos[1]
+		//	6	extvers[1]
+		//	7	extos[1]
+		//	8	flags[2]
+		//	10	meth[2]
+		//	12	modtime[2]
+		//	14	moddate[2]
+		//	16	crc[4]
+		//	20	csize[4]
+		//	24	uncsize[4]
+		//	28	namelen[2]
+		//	30	xlen[2]
+		//	32	fclen[2]
+		//	34	disknum[2]
+		//	36	iattr[2]
+		//	38	eattr[4]
+		//	42	off[4]
+		//	46	name[namelen]
+		//	46+namelen+xlen+fclen - next header
+		//
+		if get4(buf) != zcheader {
+			break
+		}
+		meth := get2(buf[10:])
+		size := get4(buf[24:])
+		namelen := get2(buf[28:])
+		xlen := get2(buf[30:])
+		fclen := get2(buf[32:])
+		off := get4(buf[42:])
+		zname := buf[46 : 46+namelen]
+		buf = buf[46+namelen+xlen+fclen:]
+		if string(zname) != name {
+			continue
+		}
+		if meth != 0 {
+			return nil, errors.New("unsupported compression for " + name + " in " + zipfile)
+		}
+
+		// zip per-file header layout:
+		//	0	magic[4]
+		//	4	extvers[1]
+		//	5	extos[1]
+		//	6	flags[2]
+		//	8	meth[2]
+		//	10	modtime[2]
+		//	12	moddate[2]
+		//	14	crc[4]
+		//	18	csize[4]
+		//	22	uncsize[4]
+		//	26	namelen[2]
+		//	28	xlen[2]
+		//	30	name[namelen]
+		//	30+namelen+xlen - file data
+		//
+		buf = make([]byte, zheadersize+namelen)
+		if err := preadn(fd, buf, off); err != nil ||
+			get4(buf) != zheader ||
+			get2(buf[8:]) != meth ||
+			get2(buf[26:]) != namelen ||
+			string(buf[30:30+namelen]) != name {
+			return nil, errors.New("corrupt zip file " + zipfile)
+		}
+		xlen = get2(buf[28:])
+
+		buf = make([]byte, size)
+		if err := preadn(fd, buf, off+30+namelen+xlen); err != nil {
+			return nil, errors.New("corrupt zip file " + zipfile)
+		}
+
+		return buf, nil
+	}
+
+	return nil, syscall.ENOENT
+}
+
+// loadTzinfoFromTzdata returns the time zone information of the time zone
+// with the given name, from a tzdata database file as they are typically
+// found on android.
+var loadTzinfoFromTzdata func(file, name string) ([]byte, error)
+
+// loadTzinfo returns the time zone information of the time zone
+// with the given name, from a given source. A source may be a
+// timezone database directory, tzdata database file or an uncompressed
+// zip file, containing the contents of such a directory.
+func loadTzinfo(name string, source string) ([]byte, error) {
+	if len(source) >= 6 && source[len(source)-6:] == "tzdata" {
+		return loadTzinfoFromTzdata(source, name)
+	}
+	return loadTzinfoFromDirOrZip(source, name)
+}
+
+// loadLocation returns the Location with the given name from one of
+// the specified sources. See loadTzinfo for a list of supported sources.
+// The first timezone data matching the given name that is successfully loaded
+// and parsed is returned as a Location.
+func loadLocation(name string, sources []string) (z *Location, firstErr error) {
+	for _, source := range sources {
+		zoneData, err := loadTzinfo(name, source)
+		if err == nil {
+			if z, err = LoadLocationFromTZData(name, zoneData); err == nil {
+				return z, nil
+			}
+		}
+		if firstErr == nil && err != syscall.ENOENT {
+			firstErr = err
+		}
+	}
+	if loadFromEmbeddedTZData != nil {
+		zoneData, err := loadFromEmbeddedTZData(name)
+		if err == nil {
+			if z, err = LoadLocationFromTZData(name, []byte(zoneData)); err == nil {
+				return z, nil
+			}
+		}
+		if firstErr == nil && err != syscall.ENOENT {
+			firstErr = err
+		}
+	}
+	if source, ok := gorootZoneSource(runtime.GOROOT()); ok {
+		zoneData, err := loadTzinfo(name, source)
+		if err == nil {
+			if z, err = LoadLocationFromTZData(name, zoneData); err == nil {
+				return z, nil
+			}
+		}
+		if firstErr == nil && err != syscall.ENOENT {
+			firstErr = err
+		}
+	}
+	if firstErr != nil {
+		return nil, firstErr
+	}
+	return nil, errors.New("unknown time zone " + name)
+}
+
+// readFile reads and returns the content of the named file.
+// It is a trivial implementation of os.ReadFile, reimplemented
+// here to avoid depending on io/ioutil or os.
+// It returns an error if name exceeds maxFileSize bytes.
+func readFile(name string) ([]byte, error) {
+	f, err := open(name)
+	if err != nil {
+		return nil, err
+	}
+	defer closefd(f)
+	var (
+		buf [4096]byte
+		ret []byte
+		n   int
+	)
+	for {
+		n, err = read(f, buf[:])
+		if n > 0 {
+			ret = append(ret, buf[:n]...)
+		}
+		if n == 0 || err != nil {
+			break
+		}
+		if len(ret) > maxFileSize {
+			return nil, fileSizeError(name)
+		}
+	}
+	return ret, err
+}
diff --git a/src/time/zoneinfo_test.go b/src/time/zoneinfo_test.go
new file mode 100644
index 0000000..8cd37b5
--- /dev/null
+++ b/src/time/zoneinfo_test.go
@@ -0,0 +1,350 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"errors"
+	"fmt"
+	"internal/testenv"
+	"os"
+	"reflect"
+	"testing"
+	"time"
+)
+
+func init() {
+	if time.ZoneinfoForTesting() != nil {
+		panic(fmt.Errorf("zoneinfo initialized before first LoadLocation"))
+	}
+}
+
+func TestEnvVarUsage(t *testing.T) {
+	time.ResetZoneinfoForTesting()
+
+	const testZoneinfo = "foo.zip"
+	const env = "ZONEINFO"
+
+	t.Setenv(env, testZoneinfo)
+
+	// Result isn't important, we're testing the side effect of this command
+	time.LoadLocation("Asia/Jerusalem")
+	defer time.ResetZoneinfoForTesting()
+
+	if zoneinfo := time.ZoneinfoForTesting(); testZoneinfo != *zoneinfo {
+		t.Errorf("zoneinfo does not match env variable: got %q want %q", *zoneinfo, testZoneinfo)
+	}
+}
+
+func TestBadLocationErrMsg(t *testing.T) {
+	time.ResetZoneinfoForTesting()
+	loc := "Asia/SomethingNotExist"
+	want := errors.New("unknown time zone " + loc)
+	_, err := time.LoadLocation(loc)
+	if err.Error() != want.Error() {
+		t.Errorf("LoadLocation(%q) error = %v; want %v", loc, err, want)
+	}
+}
+
+func TestLoadLocationValidatesNames(t *testing.T) {
+	time.ResetZoneinfoForTesting()
+	const env = "ZONEINFO"
+	t.Setenv(env, "")
+
+	bad := []string{
+		"/usr/foo/Foo",
+		"\\UNC\foo",
+		"..",
+		"a..",
+	}
+	for _, v := range bad {
+		_, err := time.LoadLocation(v)
+		if err != time.ErrLocation {
+			t.Errorf("LoadLocation(%q) error = %v; want ErrLocation", v, err)
+		}
+	}
+}
+
+func TestVersion3(t *testing.T) {
+	undo := time.DisablePlatformSources()
+	defer undo()
+	_, err := time.LoadLocation("Asia/Jerusalem")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+// Test that we get the correct results for times before the first
+// transition time. To do this we explicitly check early dates in a
+// couple of specific timezones.
+func TestFirstZone(t *testing.T) {
+	undo := time.DisablePlatformSources()
+	defer undo()
+
+	const format = "Mon, 02 Jan 2006 15:04:05 -0700 (MST)"
+	var tests = []struct {
+		zone  string
+		unix  int64
+		want1 string
+		want2 string
+	}{
+		{
+			"PST8PDT",
+			-1633269601,
+			"Sun, 31 Mar 1918 01:59:59 -0800 (PST)",
+			"Sun, 31 Mar 1918 03:00:00 -0700 (PDT)",
+		},
+		{
+			"Pacific/Fakaofo",
+			1325242799,
+			"Thu, 29 Dec 2011 23:59:59 -1100 (-11)",
+			"Sat, 31 Dec 2011 00:00:00 +1300 (+13)",
+		},
+	}
+
+	for _, test := range tests {
+		z, err := time.LoadLocation(test.zone)
+		if err != nil {
+			t.Fatal(err)
+		}
+		s := time.Unix(test.unix, 0).In(z).Format(format)
+		if s != test.want1 {
+			t.Errorf("for %s %d got %q want %q", test.zone, test.unix, s, test.want1)
+		}
+		s = time.Unix(test.unix+1, 0).In(z).Format(format)
+		if s != test.want2 {
+			t.Errorf("for %s %d got %q want %q", test.zone, test.unix, s, test.want2)
+		}
+	}
+}
+
+func TestLocationNames(t *testing.T) {
+	if time.Local.String() != "Local" {
+		t.Errorf(`invalid Local location name: got %q want "Local"`, time.Local)
+	}
+	if time.UTC.String() != "UTC" {
+		t.Errorf(`invalid UTC location name: got %q want "UTC"`, time.UTC)
+	}
+}
+
+func TestLoadLocationFromTZData(t *testing.T) {
+	undo := time.DisablePlatformSources()
+	defer undo()
+
+	const locationName = "Asia/Jerusalem"
+	reference, err := time.LoadLocation(locationName)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	gorootSource, ok := time.GorootZoneSource(testenv.GOROOT(t))
+	if !ok {
+		t.Fatal("Failed to locate tzinfo source in GOROOT.")
+	}
+	tzinfo, err := time.LoadTzinfo(locationName, gorootSource)
+	if err != nil {
+		t.Fatal(err)
+	}
+	sample, err := time.LoadLocationFromTZData(locationName, tzinfo)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !reflect.DeepEqual(reference, sample) {
+		t.Errorf("return values of LoadLocationFromTZData and LoadLocation don't match")
+	}
+}
+
+// Issue 30099.
+func TestEarlyLocation(t *testing.T) {
+	undo := time.DisablePlatformSources()
+	defer undo()
+
+	const locName = "America/New_York"
+	loc, err := time.LoadLocation(locName)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	d := time.Date(1900, time.January, 1, 0, 0, 0, 0, loc)
+	tzName, tzOffset := d.Zone()
+	if want := "EST"; tzName != want {
+		t.Errorf("Zone name == %s, want %s", tzName, want)
+	}
+	if want := -18000; tzOffset != want {
+		t.Errorf("Zone offset == %d, want %d", tzOffset, want)
+	}
+}
+
+func TestMalformedTZData(t *testing.T) {
+	// The goal here is just that malformed tzdata results in an error, not a panic.
+	issue29437 := "TZif\x00000000000000000\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0000"
+	_, err := time.LoadLocationFromTZData("abc", []byte(issue29437))
+	if err == nil {
+		t.Error("expected error, got none")
+	}
+}
+
+var slimTests = []struct {
+	zoneName   string
+	fileName   string
+	date       func(*time.Location) time.Time
+	wantName   string
+	wantOffset int
+}{
+	{
+		// 2020b slim tzdata for Europe/Berlin.
+		zoneName:   "Europe/Berlin",
+		fileName:   "2020b_Europe_Berlin",
+		date:       func(loc *time.Location) time.Time { return time.Date(2020, time.October, 29, 15, 30, 0, 0, loc) },
+		wantName:   "CET",
+		wantOffset: 3600,
+	},
+	{
+		// 2021a slim tzdata for America/Nuuk.
+		zoneName:   "America/Nuuk",
+		fileName:   "2021a_America_Nuuk",
+		date:       func(loc *time.Location) time.Time { return time.Date(2020, time.October, 29, 15, 30, 0, 0, loc) },
+		wantName:   "-03",
+		wantOffset: -10800,
+	},
+	{
+		// 2021a slim tzdata for Asia/Gaza.
+		zoneName:   "Asia/Gaza",
+		fileName:   "2021a_Asia_Gaza",
+		date:       func(loc *time.Location) time.Time { return time.Date(2020, time.October, 29, 15, 30, 0, 0, loc) },
+		wantName:   "EET",
+		wantOffset: 7200,
+	},
+	{
+		// 2021a slim tzdata for Europe/Dublin.
+		zoneName:   "Europe/Dublin",
+		fileName:   "2021a_Europe_Dublin",
+		date:       func(loc *time.Location) time.Time { return time.Date(2021, time.April, 2, 11, 12, 13, 0, loc) },
+		wantName:   "IST",
+		wantOffset: 3600,
+	},
+}
+
+func TestLoadLocationFromTZDataSlim(t *testing.T) {
+	for _, test := range slimTests {
+		tzData, err := os.ReadFile("testdata/" + test.fileName)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		reference, err := time.LoadLocationFromTZData(test.zoneName, tzData)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+
+		d := test.date(reference)
+		tzName, tzOffset := d.Zone()
+		if tzName != test.wantName {
+			t.Errorf("Zone name == %s, want %s", tzName, test.wantName)
+		}
+		if tzOffset != test.wantOffset {
+			t.Errorf("Zone offset == %d, want %d", tzOffset, test.wantOffset)
+		}
+	}
+}
+
+func TestTzset(t *testing.T) {
+	for _, test := range []struct {
+		inStr string
+		inEnd int64
+		inSec int64
+		name  string
+		off   int
+		start int64
+		end   int64
+		isDST bool
+		ok    bool
+	}{
+		{"", 0, 0, "", 0, 0, 0, false, false},
+		{"PST8PDT,M3.2.0,M11.1.0", 0, 2159200800, "PDT", -7 * 60 * 60, 2152173600, 2172733200, true, true},
+		{"PST8PDT,M3.2.0,M11.1.0", 0, 2152173599, "PST", -8 * 60 * 60, 2145916800, 2152173600, false, true},
+		{"PST8PDT,M3.2.0,M11.1.0", 0, 2152173600, "PDT", -7 * 60 * 60, 2152173600, 2172733200, true, true},
+		{"PST8PDT,M3.2.0,M11.1.0", 0, 2152173601, "PDT", -7 * 60 * 60, 2152173600, 2172733200, true, true},
+		{"PST8PDT,M3.2.0,M11.1.0", 0, 2172733199, "PDT", -7 * 60 * 60, 2152173600, 2172733200, true, true},
+		{"PST8PDT,M3.2.0,M11.1.0", 0, 2172733200, "PST", -8 * 60 * 60, 2172733200, 2177452800, false, true},
+		{"PST8PDT,M3.2.0,M11.1.0", 0, 2172733201, "PST", -8 * 60 * 60, 2172733200, 2177452800, false, true},
+		{"KST-9", 592333200, 1677246697, "KST", 9 * 60 * 60, 592333200, 1<<63 - 1, false, true},
+	} {
+		name, off, start, end, isDST, ok := time.Tzset(test.inStr, test.inEnd, test.inSec)
+		if name != test.name || off != test.off || start != test.start || end != test.end || isDST != test.isDST || ok != test.ok {
+			t.Errorf("tzset(%q, %d, %d) = %q, %d, %d, %d, %t, %t, want %q, %d, %d, %d, %t, %t", test.inStr, test.inEnd, test.inSec, name, off, start, end, isDST, ok, test.name, test.off, test.start, test.end, test.isDST, test.ok)
+		}
+	}
+}
+
+func TestTzsetName(t *testing.T) {
+	for _, test := range []struct {
+		in   string
+		name string
+		out  string
+		ok   bool
+	}{
+		{"", "", "", false},
+		{"X", "", "", false},
+		{"PST", "PST", "", true},
+		{"PST8PDT", "PST", "8PDT", true},
+		{"PST-08", "PST", "-08", true},
+		{"<A+B>+08", "A+B", "+08", true},
+	} {
+		name, out, ok := time.TzsetName(test.in)
+		if name != test.name || out != test.out || ok != test.ok {
+			t.Errorf("tzsetName(%q) = %q, %q, %t, want %q, %q, %t", test.in, name, out, ok, test.name, test.out, test.ok)
+		}
+	}
+}
+
+func TestTzsetOffset(t *testing.T) {
+	for _, test := range []struct {
+		in  string
+		off int
+		out string
+		ok  bool
+	}{
+		{"", 0, "", false},
+		{"X", 0, "", false},
+		{"+", 0, "", false},
+		{"+08", 8 * 60 * 60, "", true},
+		{"-01:02:03", -1*60*60 - 2*60 - 3, "", true},
+		{"01", 1 * 60 * 60, "", true},
+		{"100", 100 * 60 * 60, "", true},
+		{"1000", 0, "", false},
+		{"8PDT", 8 * 60 * 60, "PDT", true},
+	} {
+		off, out, ok := time.TzsetOffset(test.in)
+		if off != test.off || out != test.out || ok != test.ok {
+			t.Errorf("tzsetName(%q) = %d, %q, %t, want %d, %q, %t", test.in, off, out, ok, test.off, test.out, test.ok)
+		}
+	}
+}
+
+func TestTzsetRule(t *testing.T) {
+	for _, test := range []struct {
+		in  string
+		r   time.Rule
+		out string
+		ok  bool
+	}{
+		{"", time.Rule{}, "", false},
+		{"X", time.Rule{}, "", false},
+		{"J10", time.Rule{Kind: time.RuleJulian, Day: 10, Time: 2 * 60 * 60}, "", true},
+		{"20", time.Rule{Kind: time.RuleDOY, Day: 20, Time: 2 * 60 * 60}, "", true},
+		{"M1.2.3", time.Rule{Kind: time.RuleMonthWeekDay, Mon: 1, Week: 2, Day: 3, Time: 2 * 60 * 60}, "", true},
+		{"30/03:00:00", time.Rule{Kind: time.RuleDOY, Day: 30, Time: 3 * 60 * 60}, "", true},
+		{"M4.5.6/03:00:00", time.Rule{Kind: time.RuleMonthWeekDay, Mon: 4, Week: 5, Day: 6, Time: 3 * 60 * 60}, "", true},
+		{"M4.5.7/03:00:00", time.Rule{}, "", false},
+		{"M4.5.6/-04", time.Rule{Kind: time.RuleMonthWeekDay, Mon: 4, Week: 5, Day: 6, Time: -4 * 60 * 60}, "", true},
+	} {
+		r, out, ok := time.TzsetRule(test.in)
+		if r != test.r || out != test.out || ok != test.ok {
+			t.Errorf("tzsetName(%q) = %#v, %q, %t, want %#v, %q, %t", test.in, r, out, ok, test.r, test.out, test.ok)
+		}
+	}
+}
diff --git a/src/time/zoneinfo_unix.go b/src/time/zoneinfo_unix.go
new file mode 100644
index 0000000..b52c67d
--- /dev/null
+++ b/src/time/zoneinfo_unix.go
@@ -0,0 +1,69 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix && !ios && !android
+
+// Parse "zoneinfo" time zone file.
+// This is a fairly standard file format used on OS X, Linux, BSD, Sun, and others.
+// See tzfile(5), https://en.wikipedia.org/wiki/Zoneinfo,
+// and ftp://munnari.oz.au/pub/oldtz/
+
+package time
+
+import (
+	"syscall"
+)
+
+// Many systems use /usr/share/zoneinfo, Solaris 2 has
+// /usr/share/lib/zoneinfo, IRIX 6 has /usr/lib/locale/TZ,
+// NixOS has /etc/zoneinfo.
+var platformZoneSources = []string{
+	"/usr/share/zoneinfo/",
+	"/usr/share/lib/zoneinfo/",
+	"/usr/lib/locale/TZ/",
+	"/etc/zoneinfo",
+}
+
+func initLocal() {
+	// consult $TZ to find the time zone to use.
+	// no $TZ means use the system default /etc/localtime.
+	// $TZ="" means use UTC.
+	// $TZ="foo" or $TZ=":foo" if foo is an absolute path, then the file pointed
+	// by foo will be used to initialize timezone; otherwise, file
+	// /usr/share/zoneinfo/foo will be used.
+
+	tz, ok := syscall.Getenv("TZ")
+	switch {
+	case !ok:
+		z, err := loadLocation("localtime", []string{"/etc"})
+		if err == nil {
+			localLoc = *z
+			localLoc.name = "Local"
+			return
+		}
+	case tz != "":
+		if tz[0] == ':' {
+			tz = tz[1:]
+		}
+		if tz != "" && tz[0] == '/' {
+			if z, err := loadLocation(tz, []string{""}); err == nil {
+				localLoc = *z
+				if tz == "/etc/localtime" {
+					localLoc.name = "Local"
+				} else {
+					localLoc.name = tz
+				}
+				return
+			}
+		} else if tz != "" && tz != "UTC" {
+			if z, err := loadLocation(tz, platformZoneSources); err == nil {
+				localLoc = *z
+				return
+			}
+		}
+	}
+
+	// Fall back to UTC.
+	localLoc.name = "UTC"
+}
diff --git a/src/time/zoneinfo_unix_test.go b/src/time/zoneinfo_unix_test.go
new file mode 100644
index 0000000..92680c4
--- /dev/null
+++ b/src/time/zoneinfo_unix_test.go
@@ -0,0 +1,90 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix && !ios && !android
+
+package time_test
+
+import (
+	"os"
+	"testing"
+	"time"
+)
+
+func TestEnvTZUsage(t *testing.T) {
+	const env = "TZ"
+	tz, ok := os.LookupEnv(env)
+	if !ok {
+		defer os.Unsetenv(env)
+	} else {
+		defer os.Setenv(env, tz)
+	}
+	defer time.ForceUSPacificForTesting()
+
+	localZoneName := "Local"
+	// The file may not exist.
+	if _, err := os.Stat("/etc/localtime"); os.IsNotExist(err) {
+		localZoneName = "UTC"
+	}
+
+	cases := []struct {
+		nilFlag bool
+		tz      string
+		local   string
+	}{
+		// no $TZ means use the system default /etc/localtime.
+		{true, "", localZoneName},
+		// $TZ="" means use UTC.
+		{false, "", "UTC"},
+		{false, ":", "UTC"},
+		{false, "Asia/Shanghai", "Asia/Shanghai"},
+		{false, ":Asia/Shanghai", "Asia/Shanghai"},
+		{false, "/etc/localtime", localZoneName},
+		{false, ":/etc/localtime", localZoneName},
+	}
+
+	for _, c := range cases {
+		time.ResetLocalOnceForTest()
+		if c.nilFlag {
+			os.Unsetenv(env)
+		} else {
+			os.Setenv(env, c.tz)
+		}
+		if time.Local.String() != c.local {
+			t.Errorf("invalid Local location name for %q: got %q want %q", c.tz, time.Local, c.local)
+		}
+	}
+
+	time.ResetLocalOnceForTest()
+	// The file may not exist on Solaris 2 and IRIX 6.
+	path := "/usr/share/zoneinfo/Asia/Shanghai"
+	os.Setenv(env, path)
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		if time.Local.String() != "UTC" {
+			t.Errorf(`invalid path should fallback to UTC: got %q want "UTC"`, time.Local)
+		}
+		return
+	}
+	if time.Local.String() != path {
+		t.Errorf(`custom path should lead to path itself: got %q want %q`, time.Local, path)
+	}
+
+	timeInUTC := time.Date(2009, 1, 1, 12, 0, 0, 0, time.UTC)
+	sameTimeInShanghai := time.Date(2009, 1, 1, 20, 0, 0, 0, time.Local)
+	if !timeInUTC.Equal(sameTimeInShanghai) {
+		t.Errorf("invalid timezone: got %q want %q", timeInUTC, sameTimeInShanghai)
+	}
+
+	time.ResetLocalOnceForTest()
+	os.Setenv(env, ":"+path)
+	if time.Local.String() != path {
+		t.Errorf(`custom path should lead to path itself: got %q want %q`, time.Local, path)
+	}
+
+	time.ResetLocalOnceForTest()
+	os.Setenv(env, path[:len(path)-1])
+	if time.Local.String() != "UTC" {
+		t.Errorf(`invalid path should fallback to UTC: got %q want "UTC"`, time.Local)
+	}
+}
diff --git a/src/time/zoneinfo_wasip1.go b/src/time/zoneinfo_wasip1.go
new file mode 100644
index 0000000..b6c8bbc
--- /dev/null
+++ b/src/time/zoneinfo_wasip1.go
@@ -0,0 +1,12 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+// in wasip1 zoneinfo is managed by the runtime.
+var platformZoneSources = []string{}
+
+func initLocal() {
+	localLoc.name = "Local"
+}
diff --git a/src/time/zoneinfo_windows.go b/src/time/zoneinfo_windows.go
new file mode 100644
index 0000000..76d7975
--- /dev/null
+++ b/src/time/zoneinfo_windows.go
@@ -0,0 +1,239 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time
+
+import (
+	"errors"
+	"internal/syscall/windows/registry"
+	"syscall"
+)
+
+var platformZoneSources []string // none: Windows uses system calls instead
+
+// TODO(rsc): Fall back to copy of zoneinfo files.
+
+// BUG(brainman,rsc): On Windows, the operating system does not provide complete
+// time zone information.
+// The implementation assumes that this year's rules for daylight savings
+// time apply to all previous and future years as well.
+
+// matchZoneKey checks if stdname and dstname match the corresponding key
+// values "MUI_Std" and MUI_Dlt" or "Std" and "Dlt" (the latter down-level
+// from Vista) in the kname key stored under the open registry key zones.
+func matchZoneKey(zones registry.Key, kname string, stdname, dstname string) (matched bool, err2 error) {
+	k, err := registry.OpenKey(zones, kname, registry.READ)
+	if err != nil {
+		return false, err
+	}
+	defer k.Close()
+
+	var std, dlt string
+	if err = registry.LoadRegLoadMUIString(); err == nil {
+		// Try MUI_Std and MUI_Dlt first, fallback to Std and Dlt if *any* error occurs
+		std, err = k.GetMUIStringValue("MUI_Std")
+		if err == nil {
+			dlt, err = k.GetMUIStringValue("MUI_Dlt")
+		}
+	}
+	if err != nil { // Fallback to Std and Dlt
+		if std, _, err = k.GetStringValue("Std"); err != nil {
+			return false, err
+		}
+		if dlt, _, err = k.GetStringValue("Dlt"); err != nil {
+			return false, err
+		}
+	}
+
+	if std != stdname {
+		return false, nil
+	}
+	if dlt != dstname && dstname != stdname {
+		return false, nil
+	}
+	return true, nil
+}
+
+// toEnglishName searches the registry for an English name of a time zone
+// whose zone names are stdname and dstname and returns the English name.
+func toEnglishName(stdname, dstname string) (string, error) {
+	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones`, registry.ENUMERATE_SUB_KEYS|registry.QUERY_VALUE)
+	if err != nil {
+		return "", err
+	}
+	defer k.Close()
+
+	names, err := k.ReadSubKeyNames()
+	if err != nil {
+		return "", err
+	}
+	for _, name := range names {
+		matched, err := matchZoneKey(k, name, stdname, dstname)
+		if err == nil && matched {
+			return name, nil
+		}
+	}
+	return "", errors.New(`English name for time zone "` + stdname + `" not found in registry`)
+}
+
+// extractCAPS extracts capital letters from description desc.
+func extractCAPS(desc string) string {
+	var short []rune
+	for _, c := range desc {
+		if 'A' <= c && c <= 'Z' {
+			short = append(short, c)
+		}
+	}
+	return string(short)
+}
+
+// abbrev returns the abbreviations to use for the given zone z.
+func abbrev(z *syscall.Timezoneinformation) (std, dst string) {
+	stdName := syscall.UTF16ToString(z.StandardName[:])
+	a, ok := abbrs[stdName]
+	if !ok {
+		dstName := syscall.UTF16ToString(z.DaylightName[:])
+		// Perhaps stdName is not English. Try to convert it.
+		englishName, err := toEnglishName(stdName, dstName)
+		if err == nil {
+			a, ok = abbrs[englishName]
+			if ok {
+				return a.std, a.dst
+			}
+		}
+		// fallback to using capital letters
+		return extractCAPS(stdName), extractCAPS(dstName)
+	}
+	return a.std, a.dst
+}
+
+// pseudoUnix returns the pseudo-Unix time (seconds since Jan 1 1970 *LOCAL TIME*)
+// denoted by the system date+time d in the given year.
+// It is up to the caller to convert this local time into a UTC-based time.
+func pseudoUnix(year int, d *syscall.Systemtime) int64 {
+	// Windows specifies daylight savings information in "day in month" format:
+	// d.Month is month number (1-12)
+	// d.DayOfWeek is appropriate weekday (Sunday=0 to Saturday=6)
+	// d.Day is week within the month (1 to 5, where 5 is last week of the month)
+	// d.Hour, d.Minute and d.Second are absolute time
+	day := 1
+	t := Date(year, Month(d.Month), day, int(d.Hour), int(d.Minute), int(d.Second), 0, UTC)
+	i := int(d.DayOfWeek) - int(t.Weekday())
+	if i < 0 {
+		i += 7
+	}
+	day += i
+	if week := int(d.Day) - 1; week < 4 {
+		day += week * 7
+	} else {
+		// "Last" instance of the day.
+		day += 4 * 7
+		if day > daysIn(Month(d.Month), year) {
+			day -= 7
+		}
+	}
+	return t.sec() + int64(day-1)*secondsPerDay + internalToUnix
+}
+
+func initLocalFromTZI(i *syscall.Timezoneinformation) {
+	l := &localLoc
+
+	l.name = "Local"
+
+	nzone := 1
+	if i.StandardDate.Month > 0 {
+		nzone++
+	}
+	l.zone = make([]zone, nzone)
+
+	stdname, dstname := abbrev(i)
+
+	std := &l.zone[0]
+	std.name = stdname
+	if nzone == 1 {
+		// No daylight savings.
+		std.offset = -int(i.Bias) * 60
+		l.cacheStart = alpha
+		l.cacheEnd = omega
+		l.cacheZone = std
+		l.tx = make([]zoneTrans, 1)
+		l.tx[0].when = l.cacheStart
+		l.tx[0].index = 0
+		return
+	}
+
+	// StandardBias must be ignored if StandardDate is not set,
+	// so this computation is delayed until after the nzone==1
+	// return above.
+	std.offset = -int(i.Bias+i.StandardBias) * 60
+
+	dst := &l.zone[1]
+	dst.name = dstname
+	dst.offset = -int(i.Bias+i.DaylightBias) * 60
+	dst.isDST = true
+
+	// Arrange so that d0 is first transition date, d1 second,
+	// i0 is index of zone after first transition, i1 second.
+	d0 := &i.StandardDate
+	d1 := &i.DaylightDate
+	i0 := 0
+	i1 := 1
+	if d0.Month > d1.Month {
+		d0, d1 = d1, d0
+		i0, i1 = i1, i0
+	}
+
+	// 2 tx per year, 100 years on each side of this year
+	l.tx = make([]zoneTrans, 400)
+
+	t := Now().UTC()
+	year := t.Year()
+	txi := 0
+	for y := year - 100; y < year+100; y++ {
+		tx := &l.tx[txi]
+		tx.when = pseudoUnix(y, d0) - int64(l.zone[i1].offset)
+		tx.index = uint8(i0)
+		txi++
+
+		tx = &l.tx[txi]
+		tx.when = pseudoUnix(y, d1) - int64(l.zone[i0].offset)
+		tx.index = uint8(i1)
+		txi++
+	}
+}
+
+var usPacific = syscall.Timezoneinformation{
+	Bias: 8 * 60,
+	StandardName: [32]uint16{
+		'P', 'a', 'c', 'i', 'f', 'i', 'c', ' ', 'S', 't', 'a', 'n', 'd', 'a', 'r', 'd', ' ', 'T', 'i', 'm', 'e',
+	},
+	StandardDate: syscall.Systemtime{Month: 11, Day: 1, Hour: 2},
+	DaylightName: [32]uint16{
+		'P', 'a', 'c', 'i', 'f', 'i', 'c', ' ', 'D', 'a', 'y', 'l', 'i', 'g', 'h', 't', ' ', 'T', 'i', 'm', 'e',
+	},
+	DaylightDate: syscall.Systemtime{Month: 3, Day: 2, Hour: 2},
+	DaylightBias: -60,
+}
+
+var aus = syscall.Timezoneinformation{
+	Bias: -10 * 60,
+	StandardName: [32]uint16{
+		'A', 'U', 'S', ' ', 'E', 'a', 's', 't', 'e', 'r', 'n', ' ', 'S', 't', 'a', 'n', 'd', 'a', 'r', 'd', ' ', 'T', 'i', 'm', 'e',
+	},
+	StandardDate: syscall.Systemtime{Month: 4, Day: 1, Hour: 3},
+	DaylightName: [32]uint16{
+		'A', 'U', 'S', ' ', 'E', 'a', 's', 't', 'e', 'r', 'n', ' ', 'D', 'a', 'y', 'l', 'i', 'g', 'h', 't', ' ', 'T', 'i', 'm', 'e',
+	},
+	DaylightDate: syscall.Systemtime{Month: 10, Day: 1, Hour: 2},
+	DaylightBias: -60,
+}
+
+func initLocal() {
+	var i syscall.Timezoneinformation
+	if _, err := syscall.GetTimeZoneInformation(&i); err != nil {
+		localLoc.name = "UTC"
+		return
+	}
+	initLocalFromTZI(&i)
+}
diff --git a/src/time/zoneinfo_windows_test.go b/src/time/zoneinfo_windows_test.go
new file mode 100644
index 0000000..f23d9dc
--- /dev/null
+++ b/src/time/zoneinfo_windows_test.go
@@ -0,0 +1,71 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+	"internal/syscall/windows/registry"
+	"testing"
+	. "time"
+)
+
+func testZoneAbbr(t *testing.T) {
+	t1 := Now()
+	// discard nsec
+	t1 = Date(t1.Year(), t1.Month(), t1.Day(), t1.Hour(), t1.Minute(), t1.Second(), 0, t1.Location())
+
+	t2, err := Parse(RFC1123, t1.Format(RFC1123))
+	if err != nil {
+		t.Fatalf("Parse failed: %v", err)
+	}
+	if t1 != t2 {
+		t.Fatalf("t1 (%v) is not equal to t2 (%v)", t1, t2)
+	}
+}
+
+func TestUSPacificZoneAbbr(t *testing.T) {
+	ForceUSPacificFromTZIForTesting() // reset the Once to trigger the race
+	defer ForceUSPacificForTesting()
+	testZoneAbbr(t)
+}
+
+func TestAusZoneAbbr(t *testing.T) {
+	ForceAusFromTZIForTesting()
+	defer ForceUSPacificForTesting()
+	testZoneAbbr(t)
+}
+
+func TestToEnglishName(t *testing.T) {
+	const want = "Central Europe Standard Time"
+	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\`+want, registry.READ)
+	if err != nil {
+		t.Fatalf("cannot open CEST time zone information from registry: %s", err)
+	}
+	defer k.Close()
+
+	var std, dlt string
+	if err = registry.LoadRegLoadMUIString(); err == nil {
+		// Try MUI_Std and MUI_Dlt first, fallback to Std and Dlt if *any* error occurs
+		std, err = k.GetMUIStringValue("MUI_Std")
+		if err == nil {
+			dlt, err = k.GetMUIStringValue("MUI_Dlt")
+		}
+	}
+	if err != nil { // Fallback to Std and Dlt
+		if std, _, err = k.GetStringValue("Std"); err != nil {
+			t.Fatalf("cannot read CEST Std registry key: %s", err)
+		}
+		if dlt, _, err = k.GetStringValue("Dlt"); err != nil {
+			t.Fatalf("cannot read CEST Dlt registry key: %s", err)
+		}
+	}
+
+	name, err := ToEnglishName(std, dlt)
+	if err != nil {
+		t.Fatalf("toEnglishName failed: %s", err)
+	}
+	if name != want {
+		t.Fatalf("english name: %q, want: %q", name, want)
+	}
+}