Thanks for raising this. I hadn't anticipated this as a major concern. Is your main concern that you can't see the compiler code -- in which case would it help if the the source were available? Or is it even more than that, that you want to ensure that your build outputs are untampered and verifiably produced by a (deterministic) compiler?

I wonder though, would you trust remote CI/CD servers or Intel's proprietary C++ compiler (https://news.ycombinator.com/item?id=12363973)?