Fix raw TOML dates in where/eq

Note that this has only been a problem with "raw dates" in TOML files in /data and similar. The predefined front matter
dates `.Date` etc. are converted to a Go Time and has worked fine even after upgrading to v2 of the go-toml lib.

Fixes #9979

common/hreflect/helpers.go

@@ -20,7 +20,9 @@ import (
 	"context"
 	"reflect"
 	"sync"
+	"time"
 
+	"github.com/gohugoio/hugo/common/htime"
 	"github.com/gohugoio/hugo/common/types"
 )
 
@@ -168,6 +170,44 @@ func GetMethodIndexByName(tp reflect.Type, name string) int {
 	return m.Index
 }
 
+var (
+	timeType           = reflect.TypeOf((*time.Time)(nil)).Elem()
+	asTimeProviderType = reflect.TypeOf((*htime.AsTimeProvider)(nil)).Elem()
+)
+
+// IsTime returns whether tp is a time.Time type or if it can be converted into one
+// in ToTime.
+func IsTime(tp reflect.Type) bool {
+	if tp == timeType {
+		return true
+	}
+
+	if tp.Implements(asTimeProviderType) {
+		return true
+	}
+	return false
+}
+
+// AsTime returns v as a time.Time if possible.
+// The given location is only used if the value implements AsTimeProvider (e.g. go-toml local).
+// A zero Time and false is returned if this isn't possible.
+// Note that this function does not accept string dates.
+func AsTime(v reflect.Value, loc *time.Location) (time.Time, bool) {
+	if v.Kind() == reflect.Interface {
+		return AsTime(v.Elem(), loc)
+	}
+
+	if v.Type() == timeType {
+		return v.Interface().(time.Time), true
+	}
+
+	if v.Type().Implements(asTimeProviderType) {
+		return v.Interface().(htime.AsTimeProvider).AsTime(loc), true
+	}
+
+	return time.Time{}, false
+}
+
 // Based on: https://github.com/golang/go/blob/178a2c42254166cffed1b25fb1d3c7a5727cada6/src/text/template/exec.go#L931
 func indirectInterface(v reflect.Value) reflect.Value {
 	if v.Kind() != reflect.Interface {