If you really want to point out who gets short-changed the most it is a single person who dies before reaching retirement. ZERO benefit save the $2,500 death benefit which has never been indexed and is taxed as income on the deceased final return.

In answer to your question; the survivor would receive no additional pension at all. Public sector pensions are governed by either federal or provincial legislation which typically provides for at least a 60% survivor benefit unless the spouse had agreed to waive this entitlement.