Only tangentially related but many many years ago, I spent a good chunk of a summer internship at synopsys fixing gcc warnings in one of their products. The codebase was huge, with many parts of it more than a decade old at that point. I learned a lot about obscure corners of C. These days a frontier model could do that job in a few days (or maybe just one day if the build and testing process has been sped up - it took several hours on a dedicated cluster back then).