I had human authored GCC patches that added Linux system call builtins to GCC. I was in the middle of learning how GCC's code generation worked when my laptop fell onto the floor and my hard drive crashed, leading to the loss of the work. This was years ago, and you can even find some emails from me on the mailing list defending the feature.

AI helped me successfully restart that patch set, and take it much further than I got on my first try. Once I got that merged and perfected the contribution process, I was also planning to work on some of the feature requests that I posted on GCC's bugzilla, mainly an analyzer feature for tagged unions in C that verifies field accesses match their associated tags, and also a way to rename the "internal" symbols that GCC generates purely for aesthetic reasons.

Looks like all that stuff is gone now. Maybe it's for the best. Attempting to contribute to GNU projects hasn't exactly been a pleasant experience.