Add timezone support for front matter dates without one

Fixes #8810

tpl/time/init.go

@@ -26,7 +26,7 @@ func init() {
 		if d.Language == nil {
 			panic("Language must be set")
 		}
-		ctx := New(langs.GetTranslator(d.Language))
+		ctx := New(langs.GetTranslator(d.Language), langs.GetLocation(d.Language))
 
 		ns := &internal.TemplateFuncsNamespace{
 			Name: name,

tpl/time/time.go

@@ -16,6 +16,7 @@ package time
 
 import (
 	"fmt"
+	"time"
 	_time "time"
 
 	"github.com/gohugoio/hugo/common/htime"
@@ -25,83 +26,37 @@ import (
 	"github.com/spf13/cast"
 )
 
-var timeFormats = []string{
-	_time.RFC3339,
-	"2006-01-02T15:04:05", // iso8601 without timezone
-	_time.RFC1123Z,
-	_time.RFC1123,
-	_time.RFC822Z,
-	_time.RFC822,
-	_time.RFC850,
-	_time.ANSIC,
-	_time.UnixDate,
-	_time.RubyDate,
-	"2006-01-02 15:04:05.999999999 -0700 MST", // Time.String()
-	"2006-01-02",
-	"02 Jan 2006",
-	"2006-01-02T15:04:05-0700", // RFC3339 without timezone hh:mm colon
-	"2006-01-02 15:04:05 -07:00",
-	"2006-01-02 15:04:05 -0700",
-	"2006-01-02 15:04:05Z07:00", // RFC3339 without T
-	"2006-01-02 15:04:05Z0700",  // RFC3339 without T or timezone hh:mm colon
-	"2006-01-02 15:04:05",
-	_time.Kitchen,
-	_time.Stamp,
-	_time.StampMilli,
-	_time.StampMicro,
-	_time.StampNano,
-}
-
 // New returns a new instance of the time-namespaced template functions.
-func New(translator locales.Translator) *Namespace {
+func New(translator locales.Translator, location *time.Location) *Namespace {
 	return &Namespace{
 		timeFormatter: htime.NewTimeFormatter(translator),
+		location:      location,
 	}
 }
 
 // Namespace provides template functions for the "time" namespace.
 type Namespace struct {
 	timeFormatter htime.TimeFormatter
+	location      *time.Location
 }
 
 // AsTime converts the textual representation of the datetime string into
 // a time.Time interface.
 func (ns *Namespace) AsTime(v interface{}, args ...interface{}) (interface{}, error) {
-	if len(args) == 0 {
-		t, err := cast.ToTimeE(v)
+	loc := ns.location
+	if len(args) > 0 {
+		locStr, err := cast.ToStringE(args[0])
 		if err != nil {
 			return nil, err
 		}
-
-		return t, nil
-	}
-
-	timeStr, err := cast.ToStringE(v)
-	if err != nil {
-		return nil, err
-	}
-
-	locStr, err := cast.ToStringE(args[0])
-	if err != nil {
-		return nil, err
-	}
-
-	loc, err := _time.LoadLocation(locStr)
-	if err != nil {
-		return nil, err
-	}
-
-	// Note: Cast currently doesn't support time with non-default locations. For now, just inlining this.
-	// Reference: https://github.com/spf13/cast/pull/80
-
-	for _, dateType := range timeFormats {
-		t, err2 := _time.ParseInLocation(dateType, timeStr, loc)
-		if err2 == nil {
-			return t, nil
+		loc, err = _time.LoadLocation(locStr)
+		if err != nil {
+			return nil, err
 		}
 	}
 
-	return nil, fmt.Errorf("Unable to ParseInLocation using date %q with timezone %q", v, loc)
+	return cast.ToTimeInDefaultLocationE(v, loc)
+
 }
 
 // Format converts the textual representation of the datetime string into

tpl/time/time_test.go

@@ -23,14 +23,16 @@ import (
 func TestTimeLocation(t *testing.T) {
 	t.Parallel()
 
-	ns := New(translators.Get("en"))
+	loc, _ := time.LoadLocation("America/Antigua")
+	ns := New(translators.Get("en"), loc)
 
 	for i, test := range []struct {
 		value    string
-		location string
+		location interface{}
 		expect   interface{}
 	}{
 		{"2020-10-20", "", "2020-10-20 00:00:00 +0000 UTC"},
+		{"2020-10-20", nil, "2020-10-20 00:00:00 -0400 AST"},
 		{"2020-10-20", "America/New_York", "2020-10-20 00:00:00 -0400 EDT"},
 		{"2020-01-20", "America/New_York", "2020-01-20 00:00:00 -0500 EST"},
 		{"2020-10-20 20:33:59", "", "2020-10-20 20:33:59 +0000 UTC"},
@@ -41,7 +43,11 @@ func TestTimeLocation(t *testing.T) {
 		{"2020-01-20", "invalid-timezone", false}, // unknown time zone invalid-timezone
 		{"invalid-value", "", false},
 	} {
-		result, err := ns.AsTime(test.value, test.location)
+		var args []interface{}
+		if test.location != nil {
+			args = append(args, test.location)
+		}
+		result, err := ns.AsTime(test.value, args...)
 		if b, ok := test.expect.(bool); ok && !b {
 			if err == nil {
 				t.Errorf("[%d] AsTime didn't return an expected error, got %v", i, result)
@@ -61,7 +67,7 @@ func TestTimeLocation(t *testing.T) {
 func TestFormat(t *testing.T) {
 	t.Parallel()
 
-	ns := New(translators.Get("en"))
+	ns := New(translators.Get("en"), time.UTC)
 
 	for i, test := range []struct {
 		layout string
@@ -101,7 +107,7 @@ func TestFormat(t *testing.T) {
 func TestDuration(t *testing.T) {
 	t.Parallel()
 
-	ns := New(translators.Get("en"))
+	ns := New(translators.Get("en"), time.UTC)
 
 	for i, test := range []struct {
 		unit   interface{}