Several classes in geometry/navigation -- G4VIntersectionLocator, G4BrentLocator, G4SimpleLocator and G4MultiLevelLocator -- fail compilation when the G4DEBUG_FIELD is set. The problems primarily involve diagnostic messages which reference "mm", but there were a couple of other issues as well. I propose to fix the compilation problems directly with a new tag to navigation. None of the fixes involve changes to unprotected (production) code.
Thanks. This is now fixed in the development tag "geomnav-V10-01-21".