tpl/compare: Sort special float values as string

When sorting strings a worng order is returned. This happens because the strings are first converted
to floating values to check whether or not they should be sorted as
floating values. When an error is returned the strings will be
handled as string literals.
No error will be returned when parsing Inf, Infinity or NaN (case insensitive) because they
will be coverted to special floating point values and therefore are
legal float values.
Now we check if the returned converted values are special floating
values and treat them as string literals.

Fixes #10389

tpl/compare/compare.go

@@ -16,6 +16,7 @@ package compare
 
 import (
 	"fmt"
+	"math"
 	"reflect"
 	"strconv"
 	"time"
@@ -273,7 +274,8 @@ func (ns *Namespace) compareGetWithCollator(collator *langs.Collator, a any, b a
 	case reflect.String:
 		var err error
 		left, err = strconv.ParseFloat(av.String(), 64)
-		if err != nil {
+		// Check if float is a special floating value and cast value as string.
+		if math.IsInf(left, 0) || math.IsNaN(left) || err != nil {
 			str := av.String()
 			leftStr = &str
 		}
@@ -300,7 +302,8 @@ func (ns *Namespace) compareGetWithCollator(collator *langs.Collator, a any, b a
 	case reflect.String:
 		var err error
 		right, err = strconv.ParseFloat(bv.String(), 64)
-		if err != nil {
+		// Check if float is a special floating value and cast value as string.
+		if math.IsInf(right, 0) || math.IsNaN(right) || err != nil {
 			str := bv.String()
 			rightStr = &str
 		}

tpl/compare/compare_test.go

@@ -217,6 +217,8 @@ func doTestCompare(t *testing.T, tp tstCompareType, funcUnderTest func(a, b any)
 		{"a", "a", 0},
 		{"a", "b", -1},
 		{"b", "a", 1},
+		{"infinity", "infinity", 0},
+		{"nan", "nan", 0},
 		{tstEqerType1("a"), tstEqerType1("a"), 0},
 		{tstEqerType1("a"), tstEqerType2("a"), 0},
 		{tstEqerType2("a"), tstEqerType1("a"), 0},