Add timezone support for front matter dates without one

Fixes #8810

langs/language.go

@@ -17,6 +17,7 @@ import (
 	"sort"
 	"strings"
 	"sync"
+	"time"
 
 	translators "github.com/bep/gotranslators"
 	"github.com/go-playground/locales"
@@ -71,10 +72,13 @@ type Language struct {
 	paramsMu  sync.Mutex
 	paramsSet bool
 
-	// Used for date formatting etc. We don't want this exported to the
+	// Used for date formatting etc. We don't want these exported to the
 	// templates.
 	// TODO(bep) do the same for some of the others.
 	translator locales.Translator
+
+	locationInit sync.Once
+	location     *time.Location
 }
 
 func (l *Language) String() string {
@@ -244,9 +248,25 @@ func (l *Language) IsSet(key string) bool {
 	return l.Cfg.IsSet(key)
 }
 
+func (l *Language) getLocation() *time.Location {
+	l.locationInit.Do(func() {
+		location, err := time.LoadLocation(l.GetString("timeZone"))
+		if err != nil {
+			location = time.UTC
+		}
+		l.location = location
+	})
+
+	return l.location
+}
+
 // Internal access to unexported Language fields.
 // This construct is to prevent them from leaking to the templates.
 
 func GetTranslator(l *Language) locales.Translator {
 	return l.translator
 }
+
+func GetLocation(l *Language) *time.Location {
+	return l.getLocation()
+}