Make string sorting (e.g. ByTitle, ByLinkTitle and ByParam) language aware

Fixes #2180

tpl/collections/sort.go

@@ -20,6 +20,7 @@ import (
 	"strings"
 
 	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/langs"
 	"github.com/gohugoio/hugo/tpl/compare"
 	"github.com/spf13/cast"
 )
@@ -47,8 +48,10 @@ func (ns *Namespace) Sort(seq any, args ...any) (any, error) {
 		return nil, errors.New("can't sort " + reflect.ValueOf(seq).Type().String())
 	}
 
+	collator := langs.GetCollator(ns.deps.Language)
+
 	// Create a list of pairs that will be used to do the sort
-	p := pairList{SortAsc: true, SliceType: sliceType}
+	p := pairList{Collator: collator, SortAsc: true, SliceType: sliceType}
 	p.Pairs = make([]pair, seqv.Len())
 
 	var sortByField string
@@ -124,6 +127,10 @@ func (ns *Namespace) Sort(seq any, args ...any) (any, error) {
 			}
 		}
 	}
+
+	collator.Lock()
+	defer collator.Unlock()
+
 	return p.sort(), nil
 }
 
@@ -137,6 +144,7 @@ type pair struct {
 
 // A slice of pairs that implements sort.Interface to sort by Value.
 type pairList struct {
+	Collator  *langs.Collator
 	Pairs     []pair
 	SortAsc   bool
 	SliceType reflect.Type
@@ -151,16 +159,16 @@ func (p pairList) Less(i, j int) bool {
 	if iv.IsValid() {
 		if jv.IsValid() {
 			// can only call Interface() on valid reflect Values
-			return sortComp.Lt(iv.Interface(), jv.Interface())
+			return sortComp.LtCollate(p.Collator, iv.Interface(), jv.Interface())
 		}
 
 		// if j is invalid, test i against i's zero value
-		return sortComp.Lt(iv.Interface(), reflect.Zero(iv.Type()))
+		return sortComp.LtCollate(p.Collator, iv.Interface(), reflect.Zero(iv.Type()))
 	}
 
 	if jv.IsValid() {
 		// if i is invalid, test j against j's zero value
-		return sortComp.Lt(reflect.Zero(jv.Type()), jv.Interface())
+		return sortComp.LtCollate(p.Collator, reflect.Zero(jv.Type()), jv.Interface())
 	}
 
 	return false