To back up what ratchetfreak said, here's a presentation about someone who chose a subset of C++:
https://www.slideshare.net/Richar...restrictions-for-game-programming
It's more oriented for team projects (so I guess some of it doesn't apply for your side projects), and for game projects, but it explains the thought process to choose which features to exclude.
I had a tiny experience with Rust, and it's a language I would consider for some projects, if there wasn't its build system (cargo) that... shouldn't exist at all? And in the end, I guess we should also use only a subset of it ^^'