What will happen if we add diesel in petrol engine

There are popular IC engine which is mainly work done by fuels like Petrol, Diesel Both have unique spark point , combustion point. In petrol engine combustion is done by Spark plug without heavy compression stroke  and work is done but in diesel engine there are no spark plug combustion happen in cylinder by compression of air striking fuel injected by injectors on 1000-2000 bar . When we change the fuel vehicle will not work becoz the process should be followed for work done.