A pre-explosion optical transient event from a white dwarf merger with a giant supernova progenitor

We examine rare evolutionary routes of binary systems where the initially more massive primary star of M-1,M-0 similar or equal to 5.5-8.5 M-circle dot forms a white dwarf (WD), while the secondary star of 4 M-circle dot less than or similar to M-2,M-0 < M-1,M-0 accretes mass from the evolved primary and later terminates as a core-collapse supernova (CCSN). In such a WD-NS (neutron star) reverse evolution a NS or a potential NS-progenitor massive core is formed after the WD. These SN explosions are likely to be preceded by strong interaction of the WD with the giant secondary's core, leading to an Intermediate-Luminosity Optical Transient (ILOT; Red Transient; Red Nova) event weeks to years before the explosion. The common envelope phase of the WD and the giant ends with a merger that forms an ILOT, or an envelope ejection that leads, after a CCSN of the giant's core, to a NS-NS or WD-NS surviving binary. The WD could suffer a thermonuclear explosion that might be observed as a Type Ia SN. Most of these CCSN and thermonuclear explosions will be peculiar. We calculate the stellar evolution of representative cases using Modules for Experiments in Stellar Astrophysics (MESA). The occurrence rate of these systems is similar to 3-5 per cent of that of CCSNe.