I just made this as a youtube comment after being relatively upset about people not giving daft punk credit for their fantastic work on this, so sorry for the aggressive tone:

The guitar solo is a two-handed tapping solo, one hand aggressively hammering on and pulling off while the other hand modifies which notes the pull off returns to. This is somewhat easy for a beginner, and incredibly easy for an experienced player. The reason it sounds so "off" even if you match the tone to a piano or digital synth is because as they admitted in an interview, the end of the sound (and the song itself) was influenced by baroque music, which explains my next point:

They tuned the A to somewhere between 320 and 332 ( and adjusted the other notes accordingly (there's charts on how to do so online) because that was the standard for the frequency of "A" during that period; it's changed over time. If you play the solo in 340 (modern default) and then play it in their tuning, you'll immediately hear the difference. It's subtle, but it's there and it's the reason that people have struggled to perfectly emulate what's going on. As for the pitch bends, they did of course apply some sort of post processing to the solo but the actual solo is without a doubt, guitar with effects like distortion, maybe a wah pedal and some filters/envelope automation.

I'm not going to act like I have the exact answer but to assume it's a synth because it's technically advanced is taking away credit where credit's due.